U.S. patent application number 17/525022 was filed with the patent office on 2022-05-12 for textured surfaces for implants.
This patent application is currently assigned to Establishment Labs S.A.. The applicant listed for this patent is Establishment Labs S.A.. Invention is credited to Simon BARR, Ardeshir BAYAT, Ernie HILL.
Application Number | 20220142762 17/525022 |
Document ID | / |
Family ID | 1000006104523 |
Filed Date | 2022-05-12 |
United States Patent
Application |
20220142762 |
Kind Code |
A1 |
HILL; Ernie ; et
al. |
May 12, 2022 |
TEXTURED SURFACES FOR IMPLANTS
Abstract
An implant material having an implant surface comprising a
plurality of tissue-contacting members arranged in a regular or
irregular two-dimensional array, each tissue-contacting member
having a convex curved tissue-contacting surface. Methods of
preparing and using such implant materials.
Inventors: |
HILL; Ernie; (Manchester,
GB) ; BAYAT; Ardeshir; (Manchester, GB) ;
BARR; Simon; (Manchester, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Establishment Labs S.A. |
La Garita, |
|
CR |
|
|
Assignee: |
Establishment Labs S.A.
La Garita,
CR
|
Family ID: |
1000006104523 |
Appl. No.: |
17/525022 |
Filed: |
November 12, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15780993 |
Jun 1, 2018 |
11202698 |
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PCT/EP2016/079659 |
Dec 2, 2016 |
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17525022 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 2230/0013 20130101;
A61L 27/50 20130101; A61L 2400/18 20130101; A61F 2240/005 20130101;
A61F 2/12 20130101; A61L 27/34 20130101; A61L 2430/04 20130101;
A61F 2240/004 20130101; A61F 2/0077 20130101; A61F 2230/0071
20130101 |
International
Class: |
A61F 2/00 20060101
A61F002/00; A61F 2/12 20060101 A61F002/12; A61L 27/34 20060101
A61L027/34; A61L 27/50 20060101 A61L027/50 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 4, 2015 |
GB |
1521474.5 |
Claims
1-21. (canceled)
22. A prosthetic implant comprising a biocompatible material, the
implant having an implant surface with a biomimetic topography
comprising a plurality of tissue-contacting members, each
tissue-contacting member having a convex curved surface, wherein
the mean average height value of the plurality of tissue-contacting
members is in the range of 5 .mu.m to 150 .mu.m.
23. The implant of claim 22, wherein the mean average height value
of the plurality of tissue-contacting members is in the range of 15
.mu.m to 90 .mu.m.
24. The implant of claim 22, wherein the implant is a breast
implant.
25. The implant of claim 22, wherein the tissue-contacting members
are hemispherical in shape.
26. The implant of claim 22, wherein the height of at least 30% of
the population of the tissue-contacting members fall within a range
of 15 .mu.m to 90 .mu.m.
27. The implant of claim 22, wherein the mean average diameter of
the plurality of tissue-contacting members is in the range of 1
.mu.m to 120 .mu.m.
28. The implant of claim 22, wherein the implant surface has at
least 500 tissue-contacting members per cm.sup.2.
29. The implant of claim 22, wherein the tissue-contacting surfaces
of the plurality of tissue-contacting members comprise nano-scale
features having a height in the range of 200 nm to 800 nm.
30. The implant of claim 22, wherein the plurality of
tissue-contacting members cover at least 20% of the implant
surface.
31. The implant of claim 22, wherein each tissue-contacting member
has at least four neighboring tissue-contacting members.
32. The implant of claim 22, wherein the tissue-contacting members
are discrete members spaced from each other, or members that are
merged or fused together.
33. The implant of claim 22, wherein the implant surface is a
closed surface substantially free of pores or other open
structures.
34. A prosthetic implant comprising a biocompatible material, the
implant having an implant surface comprising a plurality of
tissue-contacting members, each tissue-contacting member having a
convex curved surface, wherein the mean average height value of the
plurality of tissue-contacting members is in the range of 15 .mu.m
to 90 .mu.m, and wherein the implant surface is a closed surface
substantially free of pores or other open structures.
35. The implant of claim 34, wherein the implant is a breast
implant.
36. The implant of claim 34, wherein the implant surface has at
least 500 tissue-contacting members per cm.sup.2.
37. The implant of claim 34, wherein each tissue-contacting member
has at least four neighboring tissue-contacting members within a
distance of 2.times. the width of the tissue-contacting member.
38. A prosthetic implant comprising a biocompatible material, the
implant having an implant surface with a biomimetic topography
comprising a plurality of tissue-contacting members, each
tissue-contacting member having a convex curved surface, wherein
the mean average height value of the plurality of tissue-contacting
members is in the range of 5 .mu.m to 150 .mu.m and the mean
average diameter of the plurality of tissue-contacting members is
from 1 .mu.m to 120 .mu.m, and wherein implant surface comprises an
organosilicon polymer.
39. The implant of claim 38, wherein the implant surface has 1000
to 50000 tissue-contacting members per cm.sup.2.
40. The implant of claim 38, wherein the implant is a breast
implant.
41. The implant of claim 38, wherein the plurality of
tissue-contacting members is a plurality of truncated hemispheres
arranged to form a two-dimensional array of fused hemispheres.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation U.S. application Ser. No.
15/780,993 filed on Jun. 1, 2018, which is the U.S. national phase
entry under 35 U.S.C. .sctn. 371 of International Application No.
PCT/EP2016/079659, filed on Dec. 2, 2016, now U.S. Pat. No.
11,202,698, each incorporated by reference in its entirety,
PCT/EP2016/079659 claiming benefit of priority to GB 1521474.5,
filed on Dec. 4, 2015.
TECHNICAL FIELD
[0002] This invention relates to biocompatible implant materials
having textured surface topographies for reducing an undesirable
cellular response upon implantation into the body and subsequent
capsular contracture formation, with particular application to
prosthetic implants, such as silicone breast implants. Methods for
preparing such surfaces, and templates useful for preparing such
surfaces are also disclosed.
BACKGROUND
[0003] Implant based surgery is performed in a variety of settings,
from reconstruction for congenital anomalies and post mastectomy
defects for oncological reasons, to augmentations for cosmetic
reasons. Unfortunately, currently available breast implants are not
without their innate complications. The most common complication
and cause for patient dissatisfaction post implantation is capsular
contracture formation.(1) 1,773,584 breast augmentations for
aesthetic reasons were declared worldwide to the International
Society of Aesthetic Plastic Surgery in 2014.(2) Capsular
contracture rates have been speculated to occur in as many as 17.5%
of implant based procedures, and therefore a significant number of
these women will have experienced capsular contracture.(3)
[0004] Capsular contracture is the exaggeration of foreign body
response of the patient's breast tissue to the breast implant. The
normal sequence of the foreign body reaction to a biomaterial
results in a capsule which walls off the implant.(4) However, in
some patients this response is exaggerated and the fibrous capsule
becomes thickened, fibrotic and less pliable which can manifest as
mastalgia, breast firmness and a poor aesthetic result. As a
consequence many patients will require reoperation to decompress
capsular contracture.(5)
[0005] Capsular contracture has been shown to be multifactorial,
with filler material, sub-muscular placement of the implant,
adjuvant radiotherapy, bacterial colonisation of the implant and
implant surface texture all being implicated in its
development.(6)
[0006] Current breast implants, with an elastomer shell and saline
or silicone gel filler evolved from a design theorised in the
1960's, which evolved into a textured, polyurethane coated implant
in the late 1960's.(7, 8) As a consequence of concern that
polyurethane was pro-cancerous and because of the ability of
polyurethane foam to reduce contracture rate, due to a belief that
implant texturing reduced contracture rates, several implant
surface textures made from silicone were developed(9, 10). Since
then the basic shell and filler construction has endured but with
subtle modifications to the texture on the surface of these
implants. The textures which are currently available are made
either by imprinting salt or polyurethane foam into the surface of
these implant shells or by moulding the implant shell from a
pre-textured mould.(11) Whilst the manufacturing techniques
employed are crude, a systematic review and a meta-analysis, have
both demonstrated the protective effect of implant texture on
capsular contracture.(12, 13) However, no study has demonstrated
that one particular implant surface is most efficient at reducing
contracture and the predominant approach of implant companies to
date has been to market their implants with little scientific
evidence to attest to their ability.
[0007] Micro and nano surface topographies have been shown to
influence cell proliferation, attachment, adhesion, migration and
morphology.(14) Many of the morphological topographies which exist
in vivo which interact with cells are those from the extra cellular
matrix (ECM) and it has been shown that the ECM of different tissue
types promote the production of tissue morphologies from where they
are derived.(15, 16) Implant textures have also been theorised to
reduce contracture by disrupting the planar capsule which surrounds
the implant and promoting the ingrowth of breast tissue.(17)
However, deep "macro-textures", with deep surface features have
also been shown to shed particulate silicone and increase the
inflammation within implant capsules.(18)
[0008] In general, implant surfaces may have a primary surface
profile made up of the surface form, which is the general shape of
the material surface. For instance, the surface of a breast implant
will generally adopt a curved form, perhaps with additional
contours/waves which may be natural features/undulations that form
as a result of the physical make-up of the implant. The way in
which such surfaces interact with body tissue at a cellular level
is however better described by reference to the surface roughness,
which refers to the topographical texture of the primary implant
surface on a smaller scale.
[0009] Breast implants are typically formed by dipping an
implant-shaped template (mandrel) into liquid polymer so that it
becomes uniformly coated. Prior to curing, the implant can be
subjected to a texturizing process such as imprinting on a mould to
create a patterned texture in silicone (e.g. Mentor Siltex.TM.
Implant). The mandrel is then placed in a hot, laminar flow cabinet
to allow for the polymer to solidify around the template (curing).
This curing step allows for an equal amount of heat to be applied
around the implant so that a homogenous surface is created. This
process can be repeated several times to increase the thickness of
the implant and the implant may then be further treated with a
solvent if it is to be smooth (to further smooth out the surface).
Silicone breast implants are thus typically made through this same
basic process, regardless of whether they are designed to be smooth
or textured.
[0010] In this regard, implant surfaces that are "smooth" do in
fact usually exhibit an unintentional minor degree of surface
roughness as a result of fine ripples, grooves and/or other surface
anomalies that are an inherent bi-product of the process by which
the surfaces are prepared (for instance forming during the curing
process as the liquid silicone trickles down the mandrel under
force of gravity).
[0011] Formally "textured" surfaces, however, typically comprise a
heavily textured surface topography. Such textures may be regular
repeating geometric patterns or may be irregular in nature.
[0012] WO2009/046425 for example describes textured implant
surfaces having a highly ordered regular geometric repeating
pattern (parallel bars) at the micro- or nano-scale which are
claimed to disrupt bacterial biofilm formation on the implant
surface. The repeating pattern is formed by production of a master
pattern using photolithographic techniques as applied in
semiconductor manufacture and the master pattern is then used to
contact print replicated patterns on the surface of the implant.
However, whilst conventional photolithographic techniques can
provide simple geometric structures such as the grooves depicted in
WO2009/046425, such methods are not attractive when more complex
geometric patterns are sought because such patterns depend on the
preparation and use of photo-masks with graded levels of opacity
through which graded levels of UV light may pass onto the
photoresist. Such photo-masks are expensive to produce and cannot
be altered once produced, meaning that each desired design/pattern
requires the prior preparation of bespoke photo-masks.
[0013] WO95/03752 (see FIG. 4) also depicts an implant surface
having a highly ordered regular geometric repeating pattern
(pillars). These uniform micro-textured surfaces may be produced by
use of ion-beam thruster technology (see e.g. page 2 of
WO95/03752). However, such uniformly patterned implant surfaces
typically lead to the orientation of fibroblasts in conformity with
the respective surface pattern (see e.g. paragraphs 28, 34 and
FIGS. 14 and 15 of WO2009/046425). As explained above, however, the
organised orientation of fibroblasts and, subsequently, collagen is
understood to be a key stage in the promotion of fibrotic capsule
contracture. Thus, while such ordering of fibroblast might be more
acceptable in external applications such as for use in wound
healing, such highly ordered patterned surfaces are not therefore
ideal for use in prosthetic implants, such as breast implants,
which are prone to capsule formation and contracture.
[0014] A variety of irregular (i.e. non-uniform) textured implant
surfaces have however been proposed in the literature with a range
of different cellular outcomes observed. A number of approaches to
providing textured surfaces have however failed to reduce or
prevent capsule formation and subsequent contracture. For instance,
paragraphs 86-89 and FIG. 7 to 9 of WO 2011/097499 describe a
number of irregular textured surfaces, which fail to provide
desirable capsule modulation. A `salt loss` technique is used in
the production of commercially available Biocell.TM. (Allergan,
Inc.). Such surfaces are described and illustrated in more detail
in [Barr, S. 2009]. This technique results in an open-cell
structure. Implant surfaces formed by this "salt loss" technique
are also depicted in FIG. 5 of WO95/03752. Such implants are not
however ideal as introduction of foreign particles to the silicone
surface may lead to detrimental effects on the silicone implant
properties, for instance if the relevant salts become encapsulated
in the silicone.
[0015] An alternative technique for forming an open-cell structure
involves the use of an open cell foam or fibrous polymeric fabric
to either form or imprint a pattern on the implant surface. For
instance, the commercially available Siltex.TM. implant (Mentor),
uses a mandrel with a polyurethane foam texture that is imprinted
into the silicone during curing. Similar fabric/open cell
foam-based texturizing techniques are also described in US
2011/0276134, WO 2011/097499 and US2002/0119177. If such open
cell-like structures are achieved using a fabric with a uniform
geometry, then open-cell structures with small-scale irregularity
but long-distance uniformity may be achieved (see e.g. FIGS. 10 and
12 of US 2011/0276134). Whilst such open cell structures are
reported to achieve some success in preventing capsule formation,
they also have drawbacks because the fine interstices and edges
formed as a result of the process may lack robustness and may break
away from the implant surface under frictional forces leading to
detached silicone fragments in the body. Furthermore, the large,
typically macroscopic, pores formed by such processes have deep
sides and pits which means that cells become embedded in the deep
valleys of the implant and cannot migrate due to sides that are too
steep for the cells to climb. Whilst this may hinder the process of
capsule formation, the cells cannot display natural migratory and
proliferative behaviour with contact inhibition of cells within
deep troughs of heavily textured implants. This is undesirable
since an adherent cell such as a fibroblast that is able to attach,
migrate, proliferate and function on a surface with minimal stress
and without inhibition, is likely to behave as a fibroblast would
in vivo within native ECM. Nonetheless, the deep troughs typically
still allow the eventual substantial in-growth of cells into the
surface pores, but whilst this may firmly anchor the implant in
place in the body, excessive tissue in-growth may lead to
difficulties later if the implant has to be removed or replaced
(for instance if capsular contraction nonetheless occurs) as a
large amount of body tissue will also have to be cut away with the
implant.
[0016] WO95/03752 discloses an alternative method for producing
irregular surface topographies in silicone breast implants by
adding filtered silicone particles to the still tacky surface of
the mandrel before curing and application of a top-coat (pages 10
to 12).
[0017] WO2015/121686, having inventors in common with the present
application, proposes an irregular textured surface modelled on the
basement membrane of the skin, the specific characteristics of the
basement membrane being such as to impart the synthetic surface
with corresponding characteristic values for mean surface roughness
Sa, root mean square height Sq, maximum peak height to trough depth
Sz, mean surface skewness Ssk, mean excess kurtosis value (Sku
minus 3), and fractal dimension.
SUMMARY OF INVENTION
[0018] The inventors propose new biomimetic textured surface
topographies for implants, particularly breast implants. The
inventors have found in particular that by controlling aspects of
the surface texture to resemble corresponding features of the
surface topography of adipose tissue improved cellular response,
indicative of reduced capsular contraction, and appropriate
cellular anchoring/in-growth could be achieved.
[0019] The inventors sought to produce an implant topography with a
provenance from the breast, specifically adipose tissue from the
breast. The inventors have employed site-specific biomimicry to
generate a novel implant surface that is adapted to its intended
implant site. Thus, when an implant comprising the novel implant
surface is implanted, as is conventional, into the tissue plane
between the adipose tissue of the breast anteriorly and the
pectoralis muscle fascia posteriorly, the surface abutting the
adipose tissue provides an effective environment for cell adhesion,
growth and proliferation.
[0020] In order to arrive at the novel implant surface, the
inventors isolated adipose tissue from the adipose tissue
interface, conducted a series of fixation techniques, characterised
it using imaging techniques, modelled it with bespoke image
analysis, and generated a synthetic replica of the observed adipose
tissue surface using 3D photolithography.
[0021] In a first aspect the present invention provides an implant
material having an implant surface, which implant surface comprises
a plurality of tissue-contacting members arranged in a regular or
irregular two-dimensional array, each tissue-contacting member
having a convex curved tissue-contacting surface.
DETAILED DESCRIPTION OF THE INVENTION
[0022] Surface Texture
[0023] The inventors have identified characteristics of adipose
tissue surface that, when reproduced on the surface of an implant,
may contribute to improved cell response and reduced capsular
contracture. In particular, one or more of the following surface
features can be reproduced on the implant surface: the
approximately hemispherical form of the adipose cells that form the
surface of the adipose tissue (against which the implant will be
placed); the close packing of the adipose cells on the surface
(which close packing effectively truncates the hemispheres, causing
them to appear to fuse together); the density of cells (cells per
unit area), that being related to the close packing; the average
size (diameter) of the adipose cells (in turn dictating the radius
of curvature that the cells present at the surface); the
distribution or variance in size (diameter); the average spacing
between adjacent cells (nearest neighbour distance); the
distribution or variance in spacing between adjacent cells (nearest
neighbour distance); the surface coverage of the cells (extent to
which the tissue surface is formed from things other than the
cells); and the height range for the nano-texture on the cell
surface (the nano-variation of height overlaid on the micro/macro
topography of the close packed approximately hemispherical adipose
cells).
[0024] Without wishing to be bound by theory, the provision of an
adipose tissue-like surface on the implant may permit the implant
to tessellate with or pack into the adipose tissue of the breast.
The biomimetic topography suitably provides an environment for
cells that is less likely than conventional implant surfaces to
cause foreign body response and especially capsular
contracture.
[0025] The implant surface of the implant material of the invention
seeks to mimic one or more of the characteristics of the adipose
tissue surface that has been carefully characterised by the
inventors.
[0026] The tissue-contacting members of the implant surface
correspond to the adipose cells that provide the adipose surface
topography. As noted above, a characteristic of the adipose tissue
surface is the array of approximately (part) hemispherical
shapes--a globular form, and so the tissue-contacting members of
the implant surface have a convex (that is, extending
outwardly/away from the surface) curved tissue-contacting surface.
The provision of an array of such convex curved surfaces mimics the
multiple curved surfaces arising from the close packing of the
adipose cells.
[0027] Suitably the convex curved tissue-contacting surface has a
radius of curvature for which the radius is approximately constant.
That is, the curvature is approximately spherical curvature.
Suitably the convex curved tissue-contacting surface corresponds to
a portion of the surface of a sphere. Suitably the convex curved
tissue-contacting surface corresponds to a substantial part of the
(curved) surface of a hemisphere.
[0028] Suitably each tissue-contacting member has the shape of part
of or all of a hemisphere.
[0029] Suitably each tissue-contacting member, or at least its
convex curved tissue-contacting surface has a globular shape. The
tissue-contacting members suitably have the shape of part or all of
a globe. That is they are, or form part of, a globule.
[0030] The tissue-contacting members can be protuberances, nodules,
raised dimples or globule such that the implant surface has a two
dimensional array of protuberances, nodules or raised dimples.
Thus, each of the protuberances, nodules, raised dimples or globule
provides a convex curved tissue-contacting surface such that the
cumulative effect of the array of such curved surfaces is to mimic
the topography of the adipose tissue surface.
[0031] As noted above, the tissue-contacting members
(protuberances, nodules or raised dimples) suitably have the shape
of part of or all of a hemisphere. The inventors believe that the
hemisphere is the shape that provides closest match to the native
adipose tissue surface.
[0032] The height of the tissue-contacting members suitably
corresponds to the height of a hemisphere having a radius of
curvature corresponding to the radius of curvature of the convex
curved tissue-contacting surface. Thus, the height suitably
corresponds to the radius of the hemisphere.
[0033] Suitably the height of the tissue-contacting members varies.
That is, the plurality of tissue-contacting members include
tissue-contacting members of different heights such that there is
height variation within the population of tissue-contacting
members.
[0034] Suitable mean average height values are in the range 1 to
200 .mu.m, suitably 1 to 150 .mu.m, suitably 5 to 150 .mu.m,
suitably 10 to 150 .mu.m, suitably 15 to 150 .mu.m, suitably 15 to
130 .mu.m, suitably 15 to 120 .mu.m, suitably 15 to 110 .mu.m,
suitably 15 to 100 .mu.m, suitably 15 to 90 .mu.m, suitably 15 to
80 .mu.m, suitably 15 to 70 .mu.m, suitably 15 to 60 .mu.m,
suitably 15 to 50 .mu.m, suitably 15 to 45 .mu.m, suitably 15 to 45
.mu.m, suitably 25 to 45 .mu.m, suitably 30 to 45 .mu.m, suitably
30 to 42 .mu.m, suitably 32 to 42 .mu.m, suitably 34 to 42 .mu.m,
suitably 34 to 40 .mu.m, suitably 35 to 40 .mu.m, suitably 36 to 40
.mu.m, suitably about 38 .mu.m. It will be clear from the preceding
ranges that a suitable lower limit for mean average height is 1
.mu.m, suitably 5 .mu.m, suitably 10 .mu.m. In the case of
spaced-apart tissue-contacting members, the height is measured from
the "base" surface located between the tissue-contacting members.
In the case of hemispherical members, the height corresponds to the
radius of the hemisphere.
[0035] Suitably at least 30% of the population of the
tissue-contacting members fall within the height range of 1 to 200
.mu.m, suitably 1 to 150 .mu.m, suitably 5 to 150 .mu.m, suitably 5
to 150 .mu.m, suitably 5 to 150 .mu.m, suitably 15 to 130 .mu.m,
suitably 15 to 120 .mu.m, suitably 15 to 110 .mu.m, suitably 15 to
100 .mu.m, suitably 15 to 90 .mu.m, suitably 15 to 80 .mu.m,
suitably 15 to 70 .mu.m, suitably 15 to 60 .mu.m, suitably 15 to 50
.mu.m, suitably 15 to 45 .mu.m, suitably 20 to 45 .mu.m. It will be
clear from the preceding ranges that a suitable lower limit for the
height is 1 .mu.m, suitably 5 .mu.m, suitably 10 .mu.m. Suitably at
least 40% of the population of the tissue-contacting members fall
within this height range, suitably at least 50% of the population,
suitably at least 60%, suitably at least 70%, suitably at least
80%, suitably at least 90%.
[0036] In embodiments where the tissue-contacting members are not
spaced apart and there is no space between the tissue-contacting
members that can be regarded as a "base" surface, a notional base
surface/plane can be obtained with reference to height profile
information (of the sort shown in FIGS. 10-1B and 10-2B, obtained
from laser confocal imaging data), with the notional base
surface/plane being plotted to coincide with the troughs/valleys
between the peaks.
[0037] In such a case the mean average height values are suitably
selected from the ranges as set out above and the following ranges:
suitably 1 to 200 .mu.m, suitably 1 to 150 .mu.m, suitably 5 to 150
.mu.m, suitably 5 to 130 .mu.m, suitably 5 to 120 .mu.m, suitably 5
to 110 .mu.m, suitably 5 to 100 .mu.m, suitably 5 to 90 .mu.m,
suitably 5 to 80 .mu.m, suitably 5 to 70 .mu.m, suitably 5 to 60
.mu.m, suitably 5 to 50 .mu.m, suitably 5 to 45 .mu.m, suitably 5
to 45 .mu.m, suitably 5 to 45 .mu.m, suitably 5 to 45 .mu.m,
suitably 5 to 40 .mu.m, suitably 5 to 35 .mu.m, suitably 5 to 32
.mu.m, suitably 5 to 30 .mu.m, suitably 5 to 28 .mu.m, suitably 5
to 25 .mu.m, suitably 10 to 40 .mu.m, suitably 10 to 35 .mu.m,
suitably 10 to 30 .mu.m, suitably 15 to 40 .mu.m, suitably 15 to 35
.mu.m. It will be clear from the preceding ranges that a suitable
lower limit for mean average height is 1 .mu.m, suitably 5 .mu.m,
suitably 10 .mu.m.
[0038] Suitably at least 30% of the population of the (non-spaced
apart) tissue-contacting members fall within the height range of 1
to 200 .mu.m, suitably 1 to 150 .mu.m, suitably 5 to 150 .mu.m,
suitably 5 to 130 .mu.m, suitably 5 to 120 .mu.m, suitably 5 to 110
.mu.m, suitably 5 to 100 .mu.m, suitably 5 to 90 .mu.m, suitably 5
to 80 .mu.m, suitably 5 to 70 .mu.m, suitably 5 to 60 .mu.m,
suitably 5 to 50 .mu.m, suitably 5 to 45 .mu.m, suitably 5 to 45
.mu.m, suitably 5 to 45 .mu.m, suitably 5 to 45 .mu.m, suitably 5
to 40 .mu.m, suitably 5 to 35 .mu.m, suitably 5 to 32 .mu.m,
suitably 5 to 30 .mu.m, suitably 5 to 28 .mu.m, suitably 5 to 25
.mu.m, suitably 10 to 40 .mu.m, suitably 10 to 35 .mu.m, suitably
10 to 30 .mu.m, suitably 15 to 40 .mu.m, suitably 15 to 35 .mu.m.
It will be clear from the preceding ranges that a suitable lower
limit for the height is 1 .mu.m, suitably 5 .mu.m, suitably 10
.mu.m. Suitably at least 40% of the population of the
tissue-contacting members fall within this height range, suitably
at least 50% of the population, suitably at least 60%, suitably at
least 70%, suitably at least 80%, suitably at least 90%.
[0039] The underlying surface of the implant material, on which the
implant surface is overlaid, may be flat or not flat. For example,
as discussed above, the implant material may have a curved shape,
e.g. to conform to the shape of the implant.
[0040] Suitably the surface coverage of the tissue-contacting
members, being the extent to which the implant surface is covered
by/provided by the tissue-contacting members, is at least 20% (% of
total implant surface area covered). The surface coverage can be
ascertained by taking measurements from suitable images of the
surface, for example an SEM image. Suitably the surface coverage of
the tissue-contacting members is at least 30%, suitably at least
40%, suitably at least 50%, suitably at least 60%, suitably at
least 70%, suitably at least 80%, suitably at least 90%, suitably
at least 95%, suitably at least 98%, suitably at least 99%,
suitably about 100%. Suitably the number of tissue-contacting
members, their size and placement, is such that the majority,
suitably at least 60%, suitably at least 70%, suitably at least
80%, suitably substantially all, suitably all of the implant
surface is provided by the convex curved tissue-contacting surfaces
of the tissue-contacting members.
[0041] This "high density" coverage is believed to be a
particularly effective mimic of the adipose tissue surface.
[0042] Suitably the implant surface has 100 to 100000
tissue-contacting members per cm.sup.2, suitably 100 to 50000,
suitably 100 to 40000, suitably 200 to 40000, suitably 400 to
40000, suitably 500 to 40000, suitably 750 to 40000, suitably 900
to 35000, suitably 1000 to 35000, suitably 1200 to 35000, suitably
1500 to 35000, suitably 1750 to 32500, suitably 2000 to 30000,
suitably 2250 to 30000, suitably 2250 to 27500, suitably 5000 to
40000, suitably 10000 to 40000, suitably 10000 to 30000, suitably
about 25000 tissue-contacting members per cm.sup.2. It will be
clear from the preceding ranges that a suitable lower limit for the
density (tissue-contacting members per cm.sup.2) of the
tissue-contacting members is 100, suitably 500, suitably 5000,
suitably 10000. It will be clear from the preceding ranges that a
suitable upper limit for the density (tissue-contacting members per
cm.sup.2) of the tissue-contacting members is 100000, suitably
50000, suitably 40000.
[0043] In embodiments the plurality of tissue-contacting members
are discrete members, in the sense that they are spaced from each
other. In embodiments the plurality of tissue-contacting members
are not discrete members. Suitably they are adjacent each other,
for example so as to appear to be merged or fused together.
[0044] Suitably the plurality of tissue-contacting members is a
plurality of truncated hemispheres arranged to form a
two-dimensional array of fused hemispheres.
[0045] Suitably the tissue-contacting members are close packed.
Suitably the tissue-contacting members are arranged so as to have a
packing structure corresponding to a layer in a close packed
structure, especially selected from hexagonal close packed (hcp)
and face centred cubic (fcc).
[0046] Suitably each tissue-contacting member has at least four,
suitably at least five, suitably six neighbours (i.e. other
tissue-contacting members).
[0047] Suitably each tissue-contacting member has at least four,
suitably at least five, suitably six neighbours (i.e. other
tissue-contacting members) within a distance corresponding to
2.times. the width (e.g. diameter) of the tissue-contacting member.
A neighbour is deemed to be located within that distance if at
least part of the neighbour is encompassed by an imaginary line
defining a circle around the tissue-contacting member, which circle
has a radius of, in the above case, 2.times. the width (e.g.
diameter) of the tissue-contacting member. Suitably the distance
corresponds to 1.5.times. the width (e.g. diameter) of the
tissue-contacting member.
[0048] Suitably the tissue-contacting members are substantially
symmetrical about an axis of rotation that is perpendicular to the
implant surface (the Z direction extending vertically from the
implant surface).
[0049] Suitably the tissue-contacting members are substantially
free from edge features and/or corner features. Suitably the
implant surface is substantially free from edge features and/or
corner features.
[0050] Suitably the implant surface has valleys formed by two or
more adjacent tissue-contacting members (E.g. adjacent (part)
hemispherical members). Indeed, the truncation of adjacent
tissue-contacting members can provide the valleys. Suitably the
valleys are interconnected. That is, one valley is joined to one or
more other valleys (suitably such other valleys themselves being
formed by adjacent tissue-contacting members). Valleys may be
joined end-to-end to form the interconnected network.
[0051] Two-dimensional array means that the tissue-contacting
members are located in an array that extends in both linear
directions parallel to the implant surface (X and Y directions).
Thus, the provision of the convex curved tissue-contacting surfaces
of the invention represents a fundamentally different approach to
surface morphologies based on grooves.
[0052] Suitably the array is a substantially hexagonal array.
[0053] Suitably the two-dimensional array is a substantially
regular two-dimensional array. This reflects the order in the
adipose tissue surface, albeit that some deviation from true
regularity exists. Nevertheless, even more regular/ordered arrays
or irregular/disordered arrangements are possible.
[0054] Suitably the mean average centre-to-centre nearest neighbour
spacing of the array of tissue-contacting members, TCMcc.sub.AVE,
is from 1 to 200 .mu.m, suitably from 1 to 150 .mu.m, suitably from
1 to 120 .mu.m, suitably from 5 to 120 .mu.m, suitably from 10 to
120 .mu.m, suitably from 20 to 120 .mu.m, suitably from 30 to 120
.mu.m, suitably from 30 to 110 .mu.m, suitably from 30 to 100
.mu.m, suitably from 40 to 100 .mu.m, suitably from 40 to 90 .mu.m,
suitably from 45 to 90 .mu.m, suitably from 50 to 90 .mu.m,
suitably from 55 to 90 .mu.m, suitably from 60 to 90 .mu.m,
suitably from 60 to 85 .mu.m, suitably from 65 to 85 .mu.m,
suitably from 65 to 80 .mu.m, suitably from 68 to 80 .mu.m,
suitably from 68 to 78 .mu.m, suitably from 69 to 75 .mu.m,
suitably from 70 to 75 .mu.m, suitably about 73 .mu.m. It will be
clear from the preceding ranges that a suitable upper limit for
mean average centre-to-centre nearest neighbour spacing is 200
.mu.m, suitably 150 .mu.m, suitably 100 .mu.m. The centre point of
a tissue-contacting member is the centre point when the implant
surface is viewed "top-down". In the case of (approximately)
hemispherical tissue-contacting members the centre point is the
centre of a circle whose circumference corresponds to the boundary
of the tissue-contacting member in the X-Y plane (i.e. the relevant
cross-section of the tissue-contacting member). In the case of
other shapes, the centre point can be obtained by selecting a
circle whose diameter is such that the circle encompasses the X-Y
cross section of the tissue-contacting member (i.e. when viewed
"top-down").
[0055] Suitably at least 30% of the population of the
tissue-contacting members have a centre-to-centre nearest neighbour
spacing in the range of from 1 to 200 .mu.m, suitably from 1 to 150
.mu.m, suitably from 1 to 120 .mu.m, suitably from 5 to 120 .mu.m,
suitably from 10 to 120 .mu.m, suitably from 20 to 120 .mu.m,
suitably from 30 to 120 .mu.m, suitably from 30 to 110 .mu.m,
suitably from 30 to 100 .mu.m, suitably from 40 to 100 .mu.m,
suitably from 40 to 90 .mu.m, suitably from 45 to 90 .mu.m,
suitably from 50 to 90 .mu.m, suitably from 55 to 90 .mu.m,
suitably from 60 to 90 .mu.m, suitably from 60 to 85 .mu.m,
suitably from 65 to 85 .mu.m, suitably from 65 to 80 .mu.m. It will
be clear from the preceding ranges that a suitable upper limit for
mean average centre-to-centre nearest neighbour spacing is 200
.mu.m, suitably 150 .mu.m, suitably 100 suitably from 1 to 120
.mu.m. Suitably at least 40% of the population of the
tissue-contacting members fall within this range, suitably at least
50% of the population, suitably at least 60%, suitably at least
70%, suitably at least 80%, suitably at least 90%.
[0056] Suitably the mean average diameter of the plurality of
tissue-contacting members, TCMd.sub.AVE, is from 1 to 200 .mu.m,
suitably from 1 to 150 .mu.m, suitably from 1 to 120 .mu.m,
suitably from 5 to 120 .mu.m, suitably from 10 to 120 .mu.m,
suitably from 20 to 120 .mu.m, suitably from 30 to 120 .mu.m,
suitably from 30 to 110 .mu.m, suitably from 30 to 100 .mu.m,
suitably from 40 to 100 .mu.m, suitably from 40 to 90 .mu.m,
suitably from 45 to 90 .mu.m, suitably from 50 to 90 .mu.m,
suitably from 55 to 90 .mu.m, suitably from 60 to 90 .mu.m,
suitably from 60 to 85 .mu.m, suitably from 65 to 85 .mu.m,
suitably from 65 to 80 .mu.m, suitably from 68 to 80 .mu.m,
suitably from 68 to 78 .mu.m, suitably from 69 to 75 .mu.m,
suitably from 70 to 75 .mu.m, suitably about 73 .mu.m. It will be
clear from the preceding ranges that a suitable upper limit for
mean average diameter is 200 .mu.m, suitably 150 .mu.m, suitably
100 .mu.m. The diameter of a tissue-contacting member can be
obtained by following the methodology outlined above to obtain the
centre point of the tissue-contacting member, whereby the circle
selected in that method provides the diameter value for the
tissue-contacting member.
[0057] Suitably at least 30% of the population of the
tissue-contacting members have a diameter in the range of from 1 to
200 .mu.m, suitably from 1 to 150 .mu.m, suitably from 1 to 120
.mu.m, suitably from 5 to 120 .mu.m, suitably from 10 to 120 .mu.m,
suitably from 20 to 120 .mu.m, suitably from 30 to 120 .mu.m,
suitably from 30 to 110 .mu.m, suitably from 30 to 100 .mu.m,
suitably from 40 to 100 .mu.m, suitably from 40 to 90 .mu.m,
suitably from 45 to 90 .mu.m, suitably from 50 to 90 .mu.m,
suitably from 55 to 90 .mu.m, suitably from 60 to 90 .mu.m,
suitably from 60 to 85 .mu.m, suitably from 65 to 85 .mu.m,
suitably from 65 to 80 .mu.m. It will be clear from the preceding
ranges that a suitable upper limit for mean average
centre-to-centre nearest neighbour spacing is 200 .mu.m, suitably
150 .mu.m, suitably 100 .mu.m. Suitably at least 40% of the
population of the tissue-contacting members fall within this range,
suitably at least 50% of the population, suitably at least 60%,
suitably at least 70%, suitably at least 80%, suitably at least
90%.
[0058] Suitably the implant surface is a closed surface. That is,
it is substantially free, suitably completely free, of pores or
other open structures. Thus, suitably the implant material is not
an open cell or porous material. This does not preclude the bulk
(i.e. underneath the surface) material having a porous or open
structure.
[0059] The implant surface may also comprise a nano-scale texture.
For example this can be achieved by the use of oxygen plasma
etching as discussed herein. The inventors have found that the
provision of such nano-texture mimics the corresponding texture on
the hemispherical surfaces of adipose cells. Suitably the
tissue-contacting surfaces of the tissue-contacting members
comprise nano-scale features (e.g. ridges or peaks) having a height
(as measured e.g. by AFM) in the range from 200 to 800 nm, suitably
300 to 700 nm. Suitably the mean height of these features is in the
range from 200 to 800 nm, suitably 300 to 700 nm, suitably 400 to
600 nm.
[0060] Surgical Use
[0061] The inventors envisage non-cosmetic use of the implant
material. For example, in reconstructive surgery or breast
augmentation, for example following oncologic surgery or
injury.
[0062] The implant material disclosed herein, suitably as part of
an implant, may be placed subcutaneously, subfascially or
submuscularly. In the case of a breast implant, the implant may be
located in the tissue plane between the adipose tissue of the
breast (anteriorly) and the pectoralis muscle fascia
(posteriorly).
[0063] Cosmetic Use
[0064] The implant material of the invention can be used in
cosmetic methods, for example a cosmetic breast enlargement
method.
[0065] Such methods may comprise the step of implanting into the
human body an implant comprising the implant material as disclosed
herein.
[0066] Implant Material
[0067] In embodiments of any of the aspects herein the implant
material comprises, suitably comprises as a major component (e.g.
at least 50 wt % of the total weight of the implant material,
preferably at least 60 wt %, more preferably at least 70 wt %, more
preferably at least 80 wt %, more preferably at least 90 wt %) in
embodiments consist substantially of, in typical embodiments
consist of, a suitable biocompatible material.
[0068] Suitably the material is capable of being shaped, e.g. by
casting etching and/or moulding into a textured surface. Suitably,
the material may comprise suitably comprises as a major component
(e.g. at least 50 wt % of the total weight of the implant material,
preferably at least 60 wt %, more preferably at least 70 wt %, more
preferably at least 80 wt %, more preferably at least 90 wt %, more
preferably at least 95 wt %, more preferably at least 99 wt %) in
embodiments consist substantially of, typically consist of, a
biocompatible synthetic polymer, suitably an organo-silicon
polymer, preferably a silicone, and more preferably
polydimethylsiloxane (PDMS).
[0069] It is particularly preferred that the surface of the implant
material for which surface roughness parameters are specified
herein (i.e. the surface intended to contact the patient's tissue,
i.e. the tissue-engaging surface) comprises the above-mentioned
biocompatible synthetic polymer. Indeed, as noted above, suitably
the surface consists substantially of an organo-silicon polymer,
preferably PDMA. Thus, in embodiments, the surface (tissue-engaging
surface) is a textured organo-silicon surface, the texture being as
described herein.
[0070] Suitably the composition of the implant material is
substantially homogeneous, especially in a depth direction from the
surface (tissue-engaging surface) into the bulk material.
[0071] The implant material suitably forms at least part of the
surface layer of the relevant implant. Thus, surfaces of implants
of the invention may partly comprise conventional implant surfaces
as well as the novel and advantageous surfaces described herein. In
embodiments, the implant material surfaces of the invention
described herein forms at least half, in suitable embodiments more
than half, preferably substantially all (e.g. at least 90%, 95%,
98% or 99% by area of the implant surface) of the tissue contacting
surface of the implant, such as wherein the tissue contacting
surface of the implant consists of said implant material. The
material comprising the surfaces of the invention may be different
to other materials in the implant or may be the same. Thus the
implant may comprise an underlayer layer of the same of different
material to the implant surface layer of the invention.
[0072] The implant may be any suitable implant capable of insertion
into a patient, preferably a prosthetic implant, optionally an
implant for internal insertion beneath the skin surface of a
patient, more preferably a breast implant.
[0073] As noted above, the implant materials of the present
invention are preferably configured so as to be inserted
subcutaneously within a patient or may be administered externally.
Preferably the implant is administered (is intended to be located)
internally, e.g. subcutaneously, subfascially or submuscularly.
[0074] Templates
[0075] In a further aspect of the invention is provided a template
for use in preparing an implant material according to any aspect or
embodiment herein. Suitably, said template comprises a textured
surface as described according to any aspect or embodiment herein,
or a negative (e.g. an inverse cast) of a textured surface as
described herein. The template may typically comprise the
3-dimensional information, i.e. X,Y,Z information, corresponding to
the implant material surface of the invention as defined according
to any aspect and embodiment herein. In embodiments, the template
is a stamp or mould, e.g. a stamp for imprinting a surface texture
of the invention onto an implant surface or moulding the implant
surface, optionally wherein the stamp or mould is a silicone stamp
or mould. Thus, a surface may be stamped or moulded a number of
times to provide an implant material having a surface as defined
above. In embodiments, the template itself is a mould. The use of
moulds is beneficial as they can be used to manufacture a large
number of implants quickly.
[0076] Methods
[0077] In an aspect of the invention is provided a method of
preparing an implant material having a textured surface comprising
the steps of acquiring spatial data in the X, Y and Z dimensions
(i.e. three-dimensional spatial data) from an adipose tissue
surface and using said spatial data to create the textured surface
of the implant.
[0078] Suitably, the use of the spatial data further comprises the
step of processing the spatial data and using the processed data to
create the textured surface of the implant.
[0079] The inventors thus propose the acquisition of 3D
image/topography data corresponding to an adipose tissue surface
for reproduction on (formation of) an implant surface. This
approach represents a considerable departure from conventional
approaches to texturising implant surfaces, which are largely based
on trial and error application of crude and often irreproducible
methods which do not provide suitable control of the implant
surfaces produced (e.g. by making open cell foam or by texturising
using salt methods).
[0080] In embodiments, the step of acquiring the spatial X,Y,Z data
is performed by any suitable contact or non-contact profilometer,
suitably by atomic force microscopy, 3D laser scanner or optical
profiler.
[0081] In embodiments, the step of creating the textured surface
using the spatial X,Y,Z data includes three dimensional printing or
photolithography or E-beam lithography, particularly optical
photolithography, e.g. UV lithography, e.g. using a laser writer.
In an embodiment, the method includes the step of processing the 3D
data (spatial X,Y,Z) by converting, suitably digitally converting
the respective data to a form of data that can be read by a
maskless lithography system. In an embodiment, the processing step
includes formation of a two or more 8 bit (or optionally 16 bit)
grayscale image wherein the 256 (e.g. or optionally 65536)
different grayscale intensities corresponds to changes in vertical
height of a measured surface. Alternatively or additionally, the
processing step includes joining two or more grayscale images
(maps) to form a mosaic montage of surface images prior to applying
the image to a surface, for example prior to assigning a number of
radiation doses on every pixel and thus controlling the exposure of
the photoresist.
[0082] Use of such methods thus allows the production of controlled
surface features in an implant surface, which are, based on the
reproduction of surface features taken from an adipose tissue
environment and not from surfaces manufactured by the crude and
uncontrolled ways reported in prior art. The method is more
versatile than prior art methods and adaptation of the digital
X,Y,Z information can provide not only the cell topography itself,
but a variety of surface topographies using the adipose tissue
surface features as the original inspiration. Processing and
manipulation of the surface data during the lithography or printing
allows for reproduction of an endless range of surface designs.
[0083] Use of Electron Beam (E-beam) Lithography may allow the
reproduction of features that are <50 nm in lateral resolution.
Thus, in an embodiment, the process of forming the surface of the
invention from using the spatial X,Y,Z data includes using Electron
Beam (E-beam) Lithography.
[0084] In embodiments, the method further comprises using the
spatial X,Y,Z data to expose a photoresist (for example an E-beam
photoresist) comprising the respective X,Y,Z information.
[0085] The method suitably includes use of the exposed and
developed photoresist (for example an E-beam resist) to form the
textured surface. The step of using the exposed and developed
photoresist to transfer the textured surface onto a template may
optionally comprise using an etching method, optionally oxygen
etching and/or deep reactive ion etching.
[0086] Embodiments of the method include use of the spatial X,Y,Z
data to expose the photoresist and/or an e-beam resist comprising
using the spatial X,Y,Z data to instruct the delivery of varying
doses of radiation to a photoresist and/or E-beam resist surface so
as to expose a photoresist and/or E-beam resist comprising the
respective X,Y,Z information. Usually photolithography methods for
preparing 3D features in objects (such as commonly used in the
semiconductor industry) use a graded photomask to control the
relative intensity of radiation received by various parts of the
photoresist during the photolithography step. However, it is
expensive and time-consuming to prepare such photomasks and once
made, they cannot be varied and must be used to make a range of
identical patterns. To the contrary, the use of the X,Y,Z data
(e.g. the colour or grayscale depiction of peak-trough height) to
control the relative intensity of radiation received at a given
point of the photoresist (such as by using laserwriter configured
to read such grayscale data) can advantageously allow for the
exposure of a photoresist having, after development, the surface
features directly rather than using a photomask. In other words, in
embodiments, the lithography method is a maskless lithography
method.
[0087] In embodiments, the step of preparing the photoresist
includes increasing or decreasing the scale of the original X, Y
and/or Z parameters for reproduction in the photoresist. This may
be used advantageously if the photoresist needs to be thinner in
the vertical direction that the vertical features of the surface
being reproduced. The features may this be scaled up again during
another step, such as using etching, e.g. deep reactive ion
etching.
[0088] In another aspect is a method of preparing an implant
material having a textured surface comprising the step of making a
cast of an adipose tissue surface, the cast containing spatial data
representing the X,Y and Z dimensions and using said cast to make
the textured implant material.
[0089] Method of Applying Texture to the Surfaces of the
Invention
[0090] In embodiments, the method comprises the step of preparing
said textured implant material surface by etching, stamping or
moulding. In embodiments, the method comprises the step of
preparing said textured implant material surface by etching. In
embodiments the method comprises the step of preparing said
textured implant material surface by stamping, optionally multiple
stamping of a single surface to produce a textured surface having a
number of stamped irregular textured regions, e.g. wherein the
stamped images cover at least half, suitably more than half, and in
embodiments substantially all of the implant surface configured to
contact a patient's tissue when inserted. In embodiments the method
comprises the step of preparing said textured implant material
surface by moulding.
[0091] In embodiments the implant material prepared by said method
is an implant material as described in any one of the aspects and
embodiments of the invention described herein.
[0092] Data Set
[0093] In an aspect of the invention is the use of spatial data
representing the X, Y and Z dimensions acquired from an dipose
tissue surface in a method of preparing a textured material or a
photoresist for use in preparing a textured material. In
embodiments, the textured material is a textured implant material
as described herein or a template as described herein.
[0094] In an aspect of the invention is a method of processing
and/or modifying spatial data in the X, Y and Z dimensions,
suitably so as to provide a data set capable of being used by a
printer, for example a laser writer or 3D printer.
[0095] In embodiments, the use includes wherein the spatial data
acquired from the adipose tissue surface is processed before use in
said method of preparation.
[0096] In an aspect of the invention is spatial data in the X, Y
and Z dimensions acquired from an adipose tissue surface.
[0097] In an aspect of the invention is a data carrier, suitably a
computer readable data carrier, comprising spatial data as defined
herein.
[0098] Tissue
[0099] In the above methods and uses, the tissue (i.e. the tissue
from which spatial data is the X, Y and Z dimensions has been
obtained or is representative of) is adipose tissue, preferably
adipose tissue of the breast.
[0100] Through mimicking the topographical cues of adipose tissue
onto the surface of a silicone implant, cells that encounter it
attach and stabilize without becoming stressed and transforming
into a pro-inflammatory/fibrotic phenotype resulting in the
initiation of chronic inflammation and fibrosis around the implant
through attraction and activation of neutrophils and macrophages.
Consequently, it is thought that the extent of the foreign body
reaction and subsequent capsular contracture formation would be
potentially averted.
[0101] Whilst it is understood that adipose tissue may be able to
effect such functions in the body, it is entirely surprising that
the excellent results achieved using the fabricated materials
prepared would show the excellent results observed when the 3D
topographic features were reproduced in silicone implant surfaces
as discussed in the examples section.
[0102] Further Aspects
[0103] In a further aspect is provided an implant material
comprising a textured surface as prepared by a method as defined
according to any aspect or embodiment herein.
[0104] Also provided is a template for use in preparing an implant
material of the invention as described herein, said template having
textured surface parameters as defined herein, or a negative of
said textured surface parameters, optionally wherein the template
is a mould or stamp, such as defined above.
[0105] The invention also provides the use of a template as
described herein in a method of making a textured implant material.
Typically the template is a silicone template, most preferably
PDMS.
[0106] Also provided is a cosmetic method comprising the step of
inserting an implant material as described in any of the aspects
and embodiments of the invention disclosed herein subcutaneously in
a patient. Suitably said method is so as to provide minimal or no
capsular contraction and/or cellular immunogenic response.
Furthermore, in embodiments the method is for reconstructions of
the breast.
[0107] General
[0108] The term "comprising" encompasses "including" as well as
"consisting" e.g. an implant "comprising" X may consist exclusively
of X or may include something additional e.g. X+Y.
[0109] The word "substantially" does not exclude "completely" e.g.
a composition which is "substantially free" from Y may be
completely free from Y. Where necessary, the word "substantially"
may be omitted from the definition of the invention.
[0110] The term "about" in relation to a numerical value x is
optional and means, for example, x.+-.10%.
[0111] The use of the term "irregular" in the context of the
surfaces of the present invention will be well understood by the
skilled person. Suitably, the term "irregular" in the context of
the surfaces of the present invention refers to surface areas which
are devoid of regular geometric patterns (such as repeating
patterns), such as at the relevant macro, micro and/or nano scales
(such as at the 1 cm.times.1 cm, 1 mm.times.1 mm, 100
micron.times.100 micron and/or at sub-micron level). The term
"irregular" in the context of the surfaces of the present invention
thus includes surfaces which appear to be disordered.
[0112] It will be appreciated on reading the present application
that the surface of implants prepared according to the present
invention may be formed by use of a stamp having an irregular
textured surface which imparts its irregular surface topography to
the implant on stamping. The stamp may thus be used repeatedly over
the surface of the implant to ultimately provide up to complete
surface coverage consisting of the substantially repeated irregular
surface imprinted by the stamp. It is thus intended that the term
"irregular" within the meaning of the present invention includes
surfaces which have more than one, such as a plurality of repeating
areas of such irregular surface topography.
DESCRIPTION OF FIGURES
[0113] FIG. 1 shows a flow diagram of the manufacture process of
the implant surfaces.
[0114] FIG. 2 shows S.E.M. image of surface of breast locule
illustrating the close-packed spherical nature of this surface.
Scale bar 100 .mu.m.
[0115] FIG. 3 is a laser confocal Height Map of Native breast
tissue.
[0116] FIG. 4 shows laser confocal output capturing the "Adipose
Original Surface".
[0117] FIG. 5 is a schematic of "Nearest neighbour" distance and
"Diameter".
[0118] FIG. 6A is a histogram of Sphere diameter.
[0119] FIG. 6B is a histogram of Nearest Neighbour Distances.
[0120] FIG. 6C is a demonstration of Matlab analysis process flow
(left to right): (A) Original bitmap of breast tissue; (B) Division
of A using thresholding of surface; (C) Centre point of thresholded
areas from B; and (D) Generated bitmap of spheres with the same
statistical properties as A (scale bars=100 .mu.m).
[0121] FIG. 7 shows Matlab defined image.
[0122] FIGS. 8A, 8B and 8C show statistical information obtained
from the model surface.
[0123] FIG. 9A shows the etched Modelled Surface.
[0124] FIG. 9B shows graph indicating nano-texture height
correlation with etch recipe.
[0125] FIG. 10 shows information on the native tissue and on the
Modelled Surface when transferred into Silicone: 1A bitmap image
height data generated from Matlab programme; 1B height profile of
bitmap 1A along the black line in 1A; 1C, a 3D representation of
the bitmap in 1A; 2A a 2D scan of the actual silicone surface
created using SU8 and scanned with a laser confocal microscope; 2B
height profile of 2A along the black line in this figure; and 2C a
3D representation of the actual modelled surface Actual Laser
confocal scanned surface.
[0126] FIGS. 11A and 11B show an S.E.M. image of Fibroblasts
adhered to Adipose surface and S.E.M. image of THP-1 Macrophages
attached to Adipose Surface.
[0127] FIGS. 12A and 12B show an S.E.M. image of Fibroblasts
adhered to Modelled surface and S.E.M. image of THP-1 Macrophages
attached to Modelled Surface.
[0128] FIG. 13 shows adipose surfaces, where images A, C, E, and G
are Fibroblasts and Macrophages adhered to surfaces shown in images
B, D, F, and H (Blue=Nuclei, Green=Focal Adhesions,
Red=Cytoskeleton).
[0129] FIG. 14 shows QRT-PCR Relative gene expressions of IL-10,
TNF-Alpha, ILB1, CD206 and IL6 compared to Tissue Culture
Plastic.
[0130] FIG. 15 shows Relative cytokine production of GRO-Alpha,
IL10, IL8 and TNF Alpha in comparison to Tissue Culture
Plastic.
[0131] The invention is described in more detail by way of example
only with reference to the following Examples and experimental
procedures.
[0132] Materials and Methods
[0133] 2 biomimetic surfaces have been created, the "original
adipose" and the "modelled adipose" surface. Tissue samples used in
this study were obtained through the Plastics and Reconstructive
Surgery Research (PRSR) Skin and Tissue Bank ethics (North West
Research Ethics Committee Ethics Code--11/NW/0683). Informed
consent was obtained from patients for the use of their tissue in
this study. All breast tissue processing was done at our Human
Tissue Authority licensed laboratory. The following describes the
characterisation and fabrication of two novel polydimethysiloxane
(PDMS) implant surfaces derived from native breast tissue
topography.
[0134] Collection of Breast Tissue and Sample Fixation
[0135] Breast tissue from three patients was collected from
elective cosmetic breast reduction operations and transported to
our lab in Dulbecco's Modified Eagle Medium (Sigma-Aldrich, UK)
supplemented with 1% penicillin and streptomycin (PAA laboratories,
Pasching, Austria), 1% L-glutamine (PAA) and 10% Fetal Bovine Serum
(PAA). Patients had no past medical history of any malignancy or
fibrotic conditions, none were obese and none smoked.
[0136] Breast tissue was washed thoroughly in warmed phosphate
buffered saline (PAA) supplemented with 1% Penicillin and
Streptomycin (PAA) before the lobules of breast adipose tissue were
dissected from the breast tissue samples. Lobules of the breast
tissue were dissected and fixed in paraformaldehyde 2%
(Sigma-Aldrich), glutaraldehyde 2.5% (Sigma-Aldrich) and 0.1M hepes
buffer (Formedium, UK) for 7 days at 4.degree. C.
[0137] Adipose tissue was washed four times in distilled water for
15 minutes each and then post fixed in osmium tetroxide 1% (Agar
Scientific, UK) in 0.1M hepes (Formedium) for 1 hour. Following two
further wash steps in distilled water of 15 minutes each, the
tissue was dehydrated using graded acetone steps of 25%, 50%, 75%,
90%, and 100%, for 15 minutes at each step. Three further washes in
100% acetone were then performed before the tissue was critical
point dried (Quorum Technologies Ltd. East Sussex, England).
[0138] Imaging, Sample Measurement and Generation of "Original
Adipose Surface"
[0139] For laser confocal imaging, fixed adipose tissue was mounted
on a scanning electron microscopy (SEM) stub and measured using an
X-100/X-200 series 3D laser confocal microscope with a 50.times.
objective (Keyence, Japan). The surface of the adipocytes was
measured using a Dimension Icon microscope (Bruker, USA),
Quantitative Force mapping using a SCANASYST-FLUID+ tip (silicon
nitride, nominal k=0.7) (Bruker). For Scanning Electron Microscopy
(SEM), mounted samples were sputter coated with gold and palladium
for 120 seconds using a SC7620 sputter coater (Quorum Technologies
Ltd, UK) and imaged using an FEI (Oregon, USA) Quanta 250 FEG
SEM.
[0140] Images from the laser confocal microscope was then exported
as an .asc point group data file. This .asc file was opened in
Gwyddion. Image background subtraction using a polynomial fit
function was used before the data was converted into an 8 bit
grayscale bitmap, containing the height data in this file as 256
grayscales. This created the "Original Adipose" surface. (FIG.
3).
[0141] Measurement of the Adipose Surface
[0142] The "Original Adipose" surface was further analysed to
define its statistical characteristics. Matlab code was engineered
to recognise boundaries between each hemisphere within these
images. This was achieved through watershed segmentation (see FIG.
6C). The maximal height of each of these segments was then
established by the code to recognise the centroid position of each
hemisphere within these segments, before a 3D sphere fit function
established the closest fit of a sphere to each segment. Code also
generated data for the nearest neighbour distance (the distance
between one centroid and the next) and hemisphere diameter. (FIG.
5)
[0143] Matlab Code Defines an "Modelled Adipose" Surface
[0144] The Matlab code produced a surface, generated from the
measurements taken from the "original adipose" surface. By
combining the hemisphere diameter and relation of each hemi-sphere
to its nearest neighbour a new "Modelled Adipose" surface was
generated with the same statistical attributes as the native
tissue. (FIG. 6C). This allowed the generation of a new "modelled
adipose" bitmap image (FIG. 7). The "modelled adipose" surface had
the same statistical attributes as that of the original adipose
surface. The statistical data is shown with the lognormal
distribution fits in FIGS. 8A, 8B and 8C.
[0145] 3D Photolithography
[0146] Following the generation of a bitmap of both the "original
adipose" and Modelled adipose" surfaces these were transferred into
PDMS using maskless grayscale lithography of a SU-8 photoresist
mould illustrated in FIG. 1.
[0147] The Base Layer
[0148] In a class 100 clean room a 4.times.4 cm plain silicon wafer
was sonicated for 10 minutes in acetone, isopropyl alcohol (IPA)
and distilled water, dried with nitrogen gas and baked on a hot
plate for 10 minutes at 150.degree. C. Hexamethyldisilazane
(Microchem, USA) was then spun onto the wafer at 3000 rpm for 45
seconds before it was returned to the hotplate for a further 10
minutes. As an adhesion layer, SU8-2000.5 (Microchem, USA) was spun
onto the wafer at 3000 rpm and ramp baked from 25.degree. C. to
95.degree. C. before being held at 95.degree. C. for 5 minutes. The
SU-8 coated wafer was flood exposed to 454 nm wavelength light for
20 seconds before being returned to the hotplate for a further 5
minutes. The SU-8 coated wafer was developed in EC solvent for 1
minute before being rinsed in IPA and baked at 150.degree. C. for
10 minutes.
[0149] The Surface Texture
[0150] A secondary, thicker layer, of SU-8 2025 (Microchem, USA)
was then spun onto the surface of the base layer coated wafer at
4000 rpm, corresponding to a thickness of 30 .mu.m. This was
followed by a ramped pre-exposure bake from 25.degree. C. to
95.degree. C. before being held at 95.degree. C. for 10
minutes.
[0151] Exposure
[0152] The wafer was exposed to either the "original adipose" or
"modelled adipose" pattern using a laser writer (LW405 Microchem,
Italy). Bitmap images were inverted prior to use using imageJ(19).
Inverted bitmap images were loaded into the laserwriter software
and pixel size was registered to 0.5 .mu.m in X and Y. A 40.times.
objective was used to expose the photoresist and laser power dose
was dictated by the corresponding grayscale level (0 being no dose
and 256 being maximum dose). Optimisation was performed on a
grayscale wedge design and bitmap images were re-formatted using a
code in Matlab to improve the linearity of the photoresist.
[0153] Development
[0154] Once the pattern had been transferred, the wafer was subject
to a post exposure bake for 10 minutes at 95.degree. C. before
development of the pattern in Mlcroposit EC solvent (Chestech Ltd,
UK) for 10 minutes with gentle agitation. Substrates were then
rinsed in IPA.
[0155] Secondary Texture
[0156] In the case of the Modelled Adipose surface, to impart a
roughness onto the surface which had statistically similar
properties to that of native adipose tissue, an oxygen etch recipe
was used to texture the surface of the SU-8 master. An Oxford
Plasmlab System 100 (Oxford, England) was used to etch the SU-8
surface for 6.5 minutes at 5 mTorr of pressure, with an RF power of
5, ICP pressure of 300 and an O2 flow rate of 45 Sccm.
[0157] Trimethylchlorosilane Vapour Acts as a Release Layer Between
Silicone and Master Mold
[0158] To passivize the surface of the SU-8 mould, to reduce
silicone bonding to this master template, trimethylchlorosilane
(TMCS, Sigma, UK) was used. The SU-8 master and 0.5 mls of TMCS
were placed under vacuum to vaporise the TMCS. The vacuum was held
for 1 hour to vaporise the TMCS and silanize the wafer.
[0159] Medical Grade Silicone Creates Adipose Surfaces in
Silicone
[0160] To mould subsequent silicone from each master wafer, MED
6215 silicone (Nusil California, US), a medical grade silicone with
permission for use in humans was used. This silicone was spun onto
the wafer at 200 rpm and cured overnight in an oven at 65.degree.
C. before being peeled from the surface of the SU8 to produce both
the "Original Adipose" and "Modelled Adipose" surface.
[0161] Substrate Characterisation
[0162] Fabricated implant surfaces were characterised using AFM,
laser confocal imaging and Scanning Electron microscopy.
[0163] Growth of THP-1 Macrophages
[0164] Human THP-1 monocyte cells were cultured in RPMI 1640
medium, "normal media" (Sigma Aldrich, UK) supplemented with 1%
penicillin and streptomycin (PAA), 1% L-glutamine (PAA) and 10%
Fetal Bovine Serum (PAA) in T75 tissue culture plastic (TCP) flasks
(Corning Incorporated, USA). Monocytes were incubated at 37.degree.
C. in 5% CO.sub.2 and media was changed weekly. THP-1 monocytes
were treated with 25 nM phorbol myristate acetate (PMA, Sigma
Aldrich, UK) for 24 hours to facilitate differentiation into
macrophages. After differentiation, macrophages were washed twice
with normal media and rested for a further 24 hrs in normal media.
Prior to seeding, macrophages were serum starved for 24 hrs in 0.5%
FBS media to synchronise these cells. Cells were seeded at 250,000
cells per well of a 24 well culture plate (Corning Incorporated,
USA) and each experiment was performed in triplicate.
[0165] Preparation of Culture Surfaces
[0166] Manufactured surfaces were cut into 15 mm disks using a
punch cutter, before being adhered to the bottom of a 24 well plate
(Corning Incorporated) using a drop of uncured MED 6215 silicone,
which was cured overnight at 65.degree. C. TCP and a smooth MED6215
silicone surface, manufactured by curing PDMS on a plain silicon
wafer were used as controls. Prior to cell seeding manufactured
surfaces were washed twice with PBS and sterilised using 70%
ethanol for 15 minutes. Manufactured implants were air dried for
half an hour and washed twice with PBS. For Confocal microscopy, 6
mm biopsies were taken of the manufactured surfaces and
[0167] RNA Extraction, cDNA Synthesis and Quantitative Real Time
Polymerase Chain Reaction
[0168] Cells were washed once with PBS, before being lysed in
buffer RLT (Qiagen, UK) and the lysate collected. RNA was extracted
using the Qiagen RNA Mini kit as per manufacturer's instructions.
RNA purity and quantity was assessed using a NanoDrop 2000c
spectrophotometer (Thermo Scientific, USA) before RNA was
transcribed to cDNA using a qScripts cDNA synthesis kit (Quanta
Biosciences, USA). qRT-PCR was performed on a LightCycler 480
machine (Roche Diagnostics, Germany) as described previously(20).
The gene expression of Tumour Necrosis Factor Alpha (TNF alpha),
Interleukin Beta1 (ILB1), Interleukin 6 (IL6), Interleukin 10
(IL10) and Mannose Receptor (CD206) were analysed. Primers and
probes were designed using the Universal Probe Library and
purchased from Sigma Aldrich, UK. ACT values were calculated by
subtracting CT values from the averaged reference gene Beta Actin.
Relative gene expressions were calculated using the
.DELTA..DELTA.CT method.
[0169] Inflammatory Marker Cytokine Array
[0170] Cell culture media was aspirated from the cell culture well
at each time point and stored at -80.degree. C. until further use.
Luminex analysis was performed by ProcartPlex.TM. Mulitplex
Immunoassay (eBioscience, Vienna, Austria) for human IL-1RA,
IL-1beta, IL-6, IL-8, IL-10, IL-12, TNF alpha, IFN gamma and GRO
alpha as per manufactures instructions.
[0171] Immunocytochemistry
[0172] Immunocytochemistry was performed on breast derived
fibroblasts for vinculin, F-Actin and DAPI. Immunocytochemistry was
performed on macrophages using Integrin .alpha.-v. Disks of the
manufactured implant surfaces were cut with a 6 mm punch biopsy,
adhered to 8 mm circular cover-slips using 3 .mu.l of mixed
MED-6215 silicone and cured at 65.degree. C. overnight, sterilising
and seeding with 10,000 macrophages or 5,000 fibroblasts.
[0173] After 24 hours of cell growth, cells were fixed in 10%
neutral buffered formalin (Sigma-Aldrich, UK) for 1 hr, washed in a
Tris Buffered Saline (TBS, Sigma-Aldrich, UK) and unreacted
formalin was quenched by incubating in 1% glycine for 30 minutes.
Fixed cells were permeabilised with 1% Triton-X 100 (Sigma-Aldrich,
UK) for 30 minutes. Cells were then washed twice before blocking in
10% Bovine Serum Albumin (BSA, Sigma-Aldrich, UK) for 1 hr. After
washing, fibroblasts were incubated in Anti-Vinculin antibody at a
dilution of 1:200 in 10% BSA (V9131, Sigma-Aldrich, UK) for 1 hr at
room temperature (RT). After washing macrophages were incubated in
Anti-Integrin .alpha.-v at a dilution of 1:750 in 10% BSA
(ab124968, Abcam, Cambridge, UK) for 1 hr at RT. Cells were washed
in TBS-Tween (TBST, 0.1% Tween in TBS) and incubated in the
secondary antibody, anti-mouse (anti-rabbit) Alexa-Fluor-488 dye
(Invitrogen, UK) at a 1:200 concentration for 1 hr at RT in the
dark. Cells were washed with TBST, incubated with Rhodamine
Phalloidin (Sigma-Aldrich, UK) at a concentration of 1:1000 for 45
minutes, with 4',6-diamidino-2-phenylindole (DAPI, 1:500 in TBST,
Invitrogen, UK) for 15 minutes before they were washed twice and
placed in PBS at 4.degree. C. until imaging.
[0174] Confocal Microscopy
[0175] Images were acquired using a Leica SP5 (Leica, Wetzlar,
Germany) inverted laser-scanning confocal microscope with an
.times.40 immersion lens. Samples were imaged in PBS and ImageJ was
used to compile z-stack slices using the maximum projection
tool.
[0176] Scanning Electron Microscopy
[0177] Growth media was removed and cells were washed twice with
0.1M hepes buffer (Formedium, UK). Cells were fixed in 2.5%
glutaraldehyde (Sigma-Aldrich) and 0.1M hepes buffer (Formedium,
UK) for 1 hr at RT. Following two wash steps in distilled water of
15 minutes each, the tissue was dehydrated through a graded series
of ethanol, 25%, 50%, 75%, 90%, and 100%, for 15 minutes at each
step. Three further washes in 100% ethanol were then performed
before the cells and implant were critical point dried (Quorum
Technologies Ltd. East Sussex, England).
[0178] Results
[0179] Adipose Surface Remains Intact after Tissue Fixation
[0180] Breast adipose tissue texture was demonstrated to be
retained after tissue fixation. S.E.M. images illustrate the
texture on the surface of these breast locules; a close packed
arrangement of spheres with a variable layer of fibres running over
their surface (FIG. 2).
[0181] Laser Confocal Microscopy Defines Adipose Locule Texture
Statistics
[0182] Laser confocal imaging (FIG. 3) shows that the natural
surface in the breast was imaged successfully by the laser confocal
microscope. The adipocytes present, the individual building blocks
of this surface, also retained their spherical nature and had not
collapsed which demonstrates that the fixation technique had
successfully preserved the structural content of these spheres.
[0183] A bitmap of the surface measurement data, where height was
represented as 256 grayscales was extracted from the laser confocal
images (FIG. 4). This defined the "Original Adipose" surface.
[0184] Laser Confocal Data Allows Extraction of Statistical Data
from the Adipose Surface
[0185] Matlab code, written to extract the statistical data of the
surface allowed measurement of nearest neighbour distances and
sphere diameters (FIG. 5).
[0186] Sphere diameters ranged from 16.8 .mu.m to 152.53 .mu.m
(mean 43.26 .mu.m, median 40.6 .mu.m, S.D. 13.69 .mu.m) (FIG. 6A),
whilst nearest neighbour distances ranged from 30.69 .mu.m to
159.09 .mu.m (mean 71.4 .mu.m, median 66.8 .mu.m, S.D. 31.77 .mu.m)
(FIG. 6B).
[0187] Matlab Code Defines the Base Structure of the "Adipose
Surface"
[0188] Based upon the recognised spheres on the surface of a
sample, Matlab code generated the base texture of the new grayscale
Modelled Adipose surface based upon the position and sphere
diameters on this surface (FIG. 6C, 7).
[0189] AFM Statistically Quantifies the Adipose Surface
[0190] Height profiles of 12 adipocytes from data were obtained
from the AFM scans of the adipocyte surfaces. Height profiles
varied between each adipocyte, but the information gained allowed a
an etch recipe to be determined to mimic the height
profiles/texture on the modelled adipose surface.
[0191] AFM scans of this nano-texture showed it has a random
roughness on its surface and a height profile which matches that of
the adipocytes.
[0192] The surface of the SU-8 mould was textured using a 6.5
minute oxygen etch recipe which produced a texture on the surface
of the mould (FIG. 12B, etched for 6.5 mins) with statistics and a
surface height which lay within the range of that measured in
native breast adipocytes.
[0193] Laser Confocal Measurement Demonstrates Successful Transfer
of the Modelled Adipose Surface into Silicone
[0194] FIG. 10-1A illustrates the height data generated by the
Matlab code for the surface of the modelled adipose surface in 2d,
as a 3D representation (10-1C) and as a graph of the profile of
this surface (10-1B) along the black line in image 10-1A. FIG. 10
2A, 2B, 2C shows the adipose modelled surface scanned using a laser
confocal microscope and the same 2D, 3D and profile results.
[0195] Growth of Human Derived Fibroblasts and Macrophages Shows
Recognition of Surface Macro-Texture
[0196] Fibroblasts and macrophages were grown in culture on the
surface of the Original Adipose and Modelled Adipose Surfaces.
Fibroblasts adhered to these surfaces and conformed to the macro
texture beneath them, orientating along the valleys of the
spherical features beneath them as shown most apparently in FIG.
11A, 12A.
[0197] Macrophages were also clustered around the circumference of
the spherical features in FIG. 11B, 12B.
[0198] No significant differences in the focal adhesion complexes
was noted between the Original Adipose and Modelled Adipose
Surfaces in both fibroblasts and macrophages. However the pattern
of macro-texture recognition and growth of fibroblasts around the
periphery of the spherical shapes beneath them was continuous in
the images shown in images A and E of FIG. 13.
[0199] Modelled Adipose Surface Induces a Positive Alteration in
Gene Profiles Cultured on its Surface when Compared to Smooth
Silicone Surfaces
[0200] As shown by FIG. 14, the Modelled adipose surface provoked a
pro-M2 polarization in THP-1 macrophages. At 12 hours TNF alpha (vs
original adipose p=0.0008, vs smooth p=0.0008), ILB1 (vs original
adipose p=0.0007, vs smooth p=0.0006) and IL6 (vs smooth p=0.0006)
had the lowest relative gene expression in the modelled surface
compared to the smooth and Original Adipose Surface. At 24 hours
IL10 which is an anti-inflammatory cytokine had the highest
expression in the modelled adipose surface compared to the Original
Adipose surface (p=0.0003) and the smooth surface (p=0.0003).
CD206, which is a marker of M2a phenotype had a higher relative
expression in the Modelled Adipose surface when compared to the
smooth surface at 12 hours (p=0.0001) and a higher than Original
Adipose surface (p<0.0001).
[0201] It can also be seen that in many cases, the manufactured
surfaces had less inflammatory influence on THP-1 macrophages than
tissue culture plastic itself.
[0202] Modelled Adipose Surface Induces a Positive Alteration in
Cytokine Expression in Macrophages Cultured on its Surface
[0203] Cytokine profiles of the same macrophages analysed in the
PCR data above, reinforced the fact that the Modelled Adipose
Surface provoked a positive effect on THP-1 Macrophages (FIG. 15).
At 12 hours, the Modelled Adipose Surface provoked the highest
production of anti-inflammatory cytokine IL10 (vs Original Adipose
p=0.0032 and vs smooth p=0.0186) and the lowest production of
anti-inflammatory Gro-Alpha (vs Original Adipose p=0.0031 and vs
smooth p=0.0192), TNF-Alpha (vs Original Adipose p<0.0001 and vs
smooth p=0.0186), neutrophil chemoattractant IL8 (vs Original
Adipose p=0.0035 and vs smooth p=0.0134). At 24 Hours IL8 levels
again showed lowest levels in the Modelled Adipose Surface (vs
Original Adipose p=0.0098 and vs smooth p=0.0477).
[0204] Observations
[0205] The novel surface texture has been shown to reduce the
inflammatory response of macrophages and induce an alternatively
activated macrophage phenotype in the initial biomaterial in-vitro
response.
[0206] Via careful surface analysis and subsequent modelling, the
inventors have characterised the relevant features of native breast
adipose tissue. Specifically, this has led to a better
understanding of the shapes and arrangement of features on the
surface of native breast tissue and this in turn has assisted
replication of these features in silicone. By combining a
photolithographic technique and oxygen plasma etching, usually
reserved for the microelectronics industry, a complex overlaid
micro- and nano-texture has been achieved in the surface of medical
grade silicone, which mimics that found within the breast.
[0207] To examine the in-vitro effect of implant texture a
challenging macrophage-based assay has been used, being a cell type
with an undisputed role in the regulation of the foreign body
reaction.(25) Macrophages arrive at the biomaterial wound interface
within the first few hours and remain for several days and dictate
the downstream foreign body reaction, which is why 12 and 24 hr
time points have been chosen to assess their reactions.(26)
Pro-inflammatory cytokines IL-1.beta.,(27), IL-6(28), TNF alpha(29)
and IL-8(30) involved in macrophage activation and IL-10(31) a
potent anti-inflammatory cytokine all have important roles in the
reaction of macrophages to biomaterial surfaces and in dictating
the remainder of the foreign body reaction.(31) IL8 and TNF-Alpha
have also been found to be upregulated in contracted fibrotic
capsules.(32) Each of the genes associated with these cytokines or
the cytokines themselves were favourably modulated by the novel
implant surface.
[0208] Fibroblasts are the traditional cell type used to assess the
reaction to implant surfaces as they generate extra cellular matrix
which is the main component of the capsule. Fibroblasts were
included in the assessment of the implant surfaces as an indicator
of cell alignment because this, with the smooth surface implants,
has been theorised to increase contracture rates.(17) Fibroblasts
are recruited from approximately 24-48 hours after the wound is
created at the end of the inflammatory phase and at the beginning
of the proliferative phase and are activated by the
chemoattractants and cytokines produced by macrophages.(33) The
implant surface has shown that the fibroblasts recognise the
surface of the implant and track along the valleys between each
hemisphere on the surface in a range of different directions, thus
breaking the alignment seen in the smooth surface implants.
[0209] Our results show that two different cell types are
influenced by surface topography and that the modulation of this
response is possible by providing a topography that mimics an
adipose tissue surface, this response being independent of implant
chemistry.(34)
[0210] A number of patents and publications are cited herein in
order to more fully describe and disclose the invention and the
state of the art to which the invention pertains. Each of these
references is incorporated herein by reference in its entirety into
the present disclosure, to the same extent as if each individual
reference was specifically and individually indicated to be
incorporated by reference.
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