U.S. patent application number 15/749563 was filed with the patent office on 2018-08-09 for medical implant based on nanocellulose.
The applicant listed for this patent is KKF UG, Universitatsklinikum Jena. Invention is credited to Wolfgang FRIED, Dieter KLEMM, Katrin PETZOLD-WELCKE, Falk RAUCHFUSS, Thomas RICHTER, Carola RUHE, Utz SETTMACHER.
Application Number | 20180221129 15/749563 |
Document ID | / |
Family ID | 53835299 |
Filed Date | 2018-08-09 |
United States Patent
Application |
20180221129 |
Kind Code |
A1 |
RAUCHFUSS; Falk ; et
al. |
August 9, 2018 |
MEDICAL IMPLANT BASED ON NANOCELLULOSE
Abstract
Medical Implant (100), comprising--a microbial cellulose tube
(1), comprising a wall (2) having an inner surface (3) and an outer
surface (4), wherein the wall comprises several layers (5, 6, 7) of
microbial cellulose, wherein said layers are concentric or
substantially concentric to a longitudinal axis (L) of the tube,--a
stent (9) which placed inside of the microbial cellulose tube (1),
wherein an outer surface (10) of the stent contacts the inner
surface (3) of the microbial cellulose tube (1), and method for
producing such implant. The implant can be covered with newly
created bile duct epithelium, thereby creating a new bile duct from
body cells. The implant can be removed after completion of creation
of the new bile duct. So, the implant as suitable as a temporary
implant. The implant can be used for surgery, such as surgery of
gall bladder, bile duct and/or liver, e.g. gall bladder removal,
hepatobiliary malignancy surgery or liver transplantation. The
implant can particularly be used for repairing or regeneration of
bile duct. Further fields of use are the use as esophagus implant
or urether implant.
Inventors: |
RAUCHFUSS; Falk; (Jena,
DE) ; SETTMACHER; Utz; (Jena, DE) ; KLEMM;
Dieter; (Weimar, DE) ; FRIED; Wolfgang; (Jena,
DE) ; RICHTER; Thomas; (Jena, DE) ;
PETZOLD-WELCKE; Katrin; (Bad Sulza OT Wickerstedt, DE)
; RUHE; Carola; (Dessau, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Universitatsklinikum Jena
KKF UG |
Jena
Jena |
|
DE
DE |
|
|
Family ID: |
53835299 |
Appl. No.: |
15/749563 |
Filed: |
August 3, 2016 |
PCT Filed: |
August 3, 2016 |
PCT NO: |
PCT/EP2016/068580 |
371 Date: |
February 1, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61L 31/005 20130101;
A61L 2420/08 20130101; A61L 31/146 20130101; A61F 2/04 20130101;
A61F 2002/041 20130101; C08L 1/02 20130101; A61L 2400/12 20130101;
A61L 31/10 20130101; A61L 31/10 20130101; C08L 1/00 20130101 |
International
Class: |
A61F 2/04 20060101
A61F002/04; A61L 31/14 20060101 A61L031/14 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 5, 2015 |
EP |
15179884.0 |
Claims
1.-15. (canceled)
16. A medical implant comprising a microbial cellulose tube, said
microbial cellulose tube comprising a wall having an inner surface
and an outer surface, wherein the wall comprises several layers of
microbial cellulose, wherein said layers are concentric or
substantially concentric to a longitudinal axis (L) of the tube;
and a stent which placed inside of the microbial cellulose tube;
wherein the microbial cellulose tube is prepared by a process, the
process comprising the steps of: a) contacting the surface of a
template which is a negative mold of a cavity of the microbial
cellulose tube and of the inner wall of the cavity, with a stock
mixture comprising a liquid culture medium and a
cellulose-producing microorganism; b) interrupting of the contact
between the template and the stock mixture, wherein on the surface
of the template, a liquid film remains comprising the liquid
culture medium and the microorganism; c) contacting of the liquid
film with an oxygen-containing atmosphere and formation of
microbial cellulose in and/or on the liquid film; d) contacting the
microbial cellulose obtained in step c) with the stock mixture; e)
interrupting the contact between the microbial cellulose and the
stock mixture wherein on the surface of the microbial cellulose is
a film of liquid is left, which comprises the liquid culture medium
and the microorganism; f) contacting the liquid film with an
oxygen-containing atmosphere and formation of microbial cellulose
in and/or on the liquid film; wherein the sequence of steps d), e)
and f) is repeated one or more times; g) separating the microbial
cellulose from the template.
17. A medical implant according to claim 16, wherein the stent is a
tubular stent.
18. A medical implant according to claim 16, wherein an outer
surface of the stent contacts the inner surface of the microbial
cellulose tube.
19. A medical implant according to claim 16, wherein the microbial
cellulose tube is expanded by the stent in a radial direction
(R).
20. A medical implant according to claim 16, wherein the stent
protrudes from the microbial cellulose tube at a first end of the
microbial cellulose tube and a second end of the microbial
cellulose tube.
21. A medical implant according to claim 16, wherein the layers of
microbial cellulose are made of fibers.
22. A medical implant according to claim 16, wherein at least the
outer surface or an outer layer of the microbial cellulose tube is
porous.
23. A medical implant according to claim 16, wherein the stent is a
biliary stent, a urinary stent or a stent for esophagus.
24. A medical implant according to claim 16, wherein the stent is
made of a polymer.
25. A method comprising performing surgery with a medical implant
according to claim 16.
26. A method according to claim 25, for use in surgery of gall
bladder, hepatobiliary malignancy surgery, bile duct, esophagus,
urether or liver.
27. A method according to claim 25, wherein the surgery is
repairing or regeneration of a bile duct, an esophagus lesion or an
urether lesion.
28. A method for producing a medical implant, comprising: producing
a microbial cellulose tube, the method comprising the steps of: a)
contacting the surface of a template which is a negative mold of a
cavity of the microbial cellulose tube and of the inner walls of
the cavity, with a stock mixture comprising a liquid culture medium
and a cellulose-producing microorganism; b) interrupting of the
contact between the template and the stock mixture, wherein on the
surface of the template, a liquid film remains comprising the
liquid culture medium and the microorganism; c) contacting of the
liquid film with an oxygen-containing atmosphere and formation of
microbial cellulose in and/or on the liquid film; d) contacting the
microbial cellulose obtained in step c) with the stock mixture, e)
interrupting the contact between the microbial cellulose and the
stock mixture wherein on the surface of the microbial cellulose is
a film of liquid is left, which comprises the liquid culture medium
and the microorganism; f) contacting the liquid film with an
oxygen-containing atmosphere and formation of microbial cellulose
in and/or on the liquid film; wherein the sequence of steps d), e)
and f) is repeated one or more times; g) separating the microbial
cellulose from the template; and introducing a stent into the
microbial cellulose tube.
29. A medical implant comprising a microbial cellulose tube, said
microbial cellulose tube comprising a wall having an inner surface
and an outer surface, wherein the wall comprises at least two
layers of microbial cellulose, wherein said at least two layers are
concentric or substantially concentric to a longitudinal axis (L)
of the tube; and a stent which placed inside of the microbial
cellulose tube.
30. A medical implant according to claim 17, wherein an outer
surface of the stent contacts the inner surface of the microbial
cellulose tube.
31. A medical implant according to claim 17, wherein the microbial
cellulose tube is expanded by the stent in a radial direction
(R).
32. A medical implant according to claim 17, wherein the stent
protrudes from the microbial cellulose tube at a first end of the
microbial cellulose tube and a second end of the microbial
cellulose tube.
33. A medical implant according to claim 17, wherein the layers of
microbial cellulose are made of fibers.
34. A medical implant according to claim 18, wherein the stent
protrudes from the microbial cellulose tube at a first end of the
microbial cellulose tube and a second end of the microbial
cellulose tube.
35. A medical implant according to claim 18, wherein the layers of
microbial cellulose are made of fibers.
Description
[0001] The present invention relates to a medical implant,
particularly for repairing a bile duct, and a method for producing
such implant.
[0002] In hepato-biliary surgery a reconstruction of the biliary
duct is often a critical issue since loss of biliary duct substance
often forces the surgeon to high-risk operations or to operations
like bilioenteric anastomosis. Such loss of substance, or lesions,
may happen when gall bladder is removed and the common bile duct is
incidentally injured or when damages are caused by ischemia, e.g.
after liver transplantation or tumor resection.
[0003] Reconstruction of such lesions is complicated. In most cases
a so called "bilioenteric anastomosis" has to be performed, which
is a connection between common bile duct and parts of the
gastrointestinal tract. In this procedure, an intestinal loop is
connected to the common bile duct. The basic problem of this method
is that sphincter mechanism is bypassed, which is the natural
barrier between biliary system and intestinal lumen. This often
results in migration of intestinal bacteria in the bile duct, which
can lead to an infection of the biliary system. Particularly
patients after a liver transplantation are affected by this problem
and endangered due to their immunosuppressed state.
[0004] Attemtps to eliminate a bile duct defect are known from only
a few scientific groups. Aikawa et al (2012) describe a bile duct
replacement by implantation of a polymeric tube that could be
resorbed. A histologic evidence of a completely regenerated bile
duct could be made no earlier than after four months, which is a
too long time for a successful application in human body. Moreover,
it is difficult to coordinate the new formation of bile duct and
resorption of the polymer tube, particularly when taking into
consideration the specific constitution and situation of an
individual patient. The same problems occur when the technique
published by Palmes et al. (2009) is used. Here, implantation of an
autologous segment of a vein (external jugular vein) was implanted
and stabilized with an absorbable or resorbable stent. With this
method, it took even six months for creating a new bile duct.
Moreover, not every patient possesses suitable veins and a further
surgical intervention is necessary in order to obtain the necessary
vein segment.
[0005] The present invention is based on the problem of providing
an improved medical implant, particularly for repairing a defect in
a bile duct. Particularly, it was an object to provide a material
for bile, bile duct and liver surgery that is able to fulfil one or
more of the following tasks: [0006] to bypass or bridge a defect in
a bile duct, preferably also over a long distance; [0007] to enable
a reconstruction of a bile duct, without using a connection between
bile or bile duct and parts of the gastro-intestinal tract; [0008]
to induce a regeneration of the bile duct epithelium.
[0009] One or more of the above objects are obtained with the
present invention. The present invention provides with a medical
implant and a method for producing such implant as stated in the
independent claims.
[0010] It has been shown that with the present invention, in
general or in specific embodiments, one or more of the following
benefits are obtained: [0011] A new bile duct from body's own
tissue could be created on the implant. Bile duct epithelium is
created on the implant. The implant creates a stimulus for
regeneration of body tissue, at least as far as a bile duct is
concerned. Defects in a bile duct can thus be repaired by using the
implant of the invention. Sufficient anastomosis can be reached.
[0012] The implant of the invention easily be produced. Diameter,
length and especially structure and properties of the inner and
outer surface of the tube can be designed directly in a bioreactor
in view of the envisaged application or situation. [0013] It is
possible to repair defects in a bile duct that extend over a longer
distance. So, a sphincter mechanism can be retained and infections
avoided. [0014] After regeneration of the bile duct, the implant
can easily be removed. The nanocellulose does not form a firm
connection to the newly created body tissue. No foreign matter
remains in the organism. [0015] The implant can be used for
permanent or temporary interposition. [0016] The nanocellulose tube
of the implant can be used as interponate, particularly for a bile
duct. [0017] In the invention it was surprisingly shown that in a
living organism a non-degradable artificial implant was covered
with newly created bile duct epithelium, thereby creating a new
bile duct from body cells. Nevertheless, the implant can be removed
after completion of creation of the new bile duct. So, the implant
is suitable as a temporary implant.
[0018] The present invention particularly provides with a medical
Implant, comprising [0019] a microbial cellulose tube, comprising a
wall having an inner surface and an outer surface, wherein the wall
comprises multiple layers of microbial cellulose, wherein said
layers are concentric or substantially concentric to a longitudinal
axis of the tube, [0020] a stent which is placed inside of the tube
of microbial cellulose.
[0021] In the implant, the microbial cellulose tube surrounds the
stent.
[0022] In one embodiment, an outer surface of the stent contacts
the inner surface of the microbial cellulose tube. In this
embodiment, the microbial cellulose tube is placed on the outer
surface of the stent.
[0023] The medical implant of the invention is preferably used as a
temporary medical implant which can be completely or partially
removed after having fulfilled its function. In partial removal,
the stent is removed from the body. When completely removed, also
the tube is removed. For clinical application, the tube and the
stent can be removed via an endoscopic approach. In our experiments
the regenerated bile duct was stable. Thus, all or nearly all
"foreign material" will be removed out of the biliary system.
[0024] According to a basic principle of the invention the
microbial cellulose tube is not the intended replacement for a bile
duct. Instead, the microbial cellulose tube is a support for growth
of a new bile duct, or bile duct segment from body's own tissue.
The implant of the invention is particularly suitable for
generating a new bile duct from body's own tissue, or for repairing
a bile duct by generating a new bile duct section from body's own
tissue between two already existing bile duct ends.
[0025] When using the implant, and at the end of use, body tissue
grows/has been grown on the surface of the microbial cellulose tube
and so, a bile duct can be created or repaired.
[0026] The stent is introduced into the microbial cellulose tube
(also abbreviated as "tube"), i.e. into the interior, also called
the cavity, of the tube. The stent keeps open the interior, or the
lumen, of the tube and prevents a closure of the tube. A stent can
lead to expansion of the tube, as described below, and thereby
improve the functionality of the implant.
[0027] Preferably, the stent is slit into the microbial cellulose
tube. The microbial cellulose tube surrounds the stent.
[0028] In one embodiment, the stent is a tubular stent. The term
tubular stent also comprises stents having one or more openings on
the surface or the jacket of the tube. The tubular stent can
comprise a tube made of a mesh structure or a tube with closed
jacket.
[0029] The outer diameter of the stent may be the same, smaller, or
higher, particularly slightly higher, than the inner diameter of
the microbial cellulose tube. If the outer diameter of the stent is
higher, the tube is expanded. The implant may comprise an expanded
microbial cellulose tube, preferably expanded in radial direction.
Expansion means an expansion in comparison to a tube that is not
combined with the stent. The inner diameter of the cellulose tube
is the inner diameter of the tube before it is combined with the
stent.
[0030] A stent is a hollow device placed in the body and may be
used to create a passage between two hollow spaces or for keeping
open a hollow organ or a vessel. In the present invention the stent
is used as stiff support for the microbial cellulose tube. In this
sense, the stent is used for keeping open the microbial cellulose
tube. The stent can also keep open parts of an existing duct in the
body, for example parts of a bile duct.
[0031] The stent is preferably a billiary stent. The stent may be
made of polymer, particularly it can be a polymer tube. The stent
may comprise openings on its outer surface. Such openings can be
openings that are present in addition to openings at both ends of a
stent.
[0032] The stent can be over its whole length placed inside of the
tube of microbial cellulose or over a part of its length placed
inside of the tube. In one embodiment, the stent protrudes from the
microbial cellulose tube at one end (a first end) of the microbial
cellulose tube and an opposite end (a second end) of the microbial
cellulose tube. A protrusion has the advantage that protruding ends
of the stent can be inserted each into the bile duct, for example,
when between two bile duct segments new tissue shall be generated
in order to connect the segments. A protrusion means a protrusion
in longitudinal direction, i.e. in direction of the longitudinal
axis (L) of the tube.
[0033] In insertion of the implant can comprise following steps:
[0034] insertion of the stent, particularly protruding parts of the
stent, into two bile duct segments, [0035] placing the cellulose
tube between the bile duct segments. Thereby, each edge of the both
bile duct segments can be placed adjacent to an edge of the tube at
the end of the tube, respectively. Each edge of a bile duct can be
in contact to said edge of the tube. [0036] optionally: connecting
an end of the tube with a bile duct, preferably on both ends of the
tube, by connection means. The connection means may be, for
example, a suture.
[0037] After insertion of the implant, body tissue can grow over
the tube until the bile duct segments are re-connected. Then, the
implant can be removed.
[0038] In one embodiment, the outer layer of the BNC tube in the
implant is subjected to pressure or strain, which can for example
be done by expanding the BNC tube with a stent. It has been shown
that by such measure, meshes are narrowed and a structure of BNC
fibers in the outer layer is subjected to compaction. In one
embodiment, a stent with an outer diameter larger than the inner
diameter of the tube can be used, to reach this result. The inner
diameter of the tube is the inner diameter of the tube before it is
combined with the stent. By an expansion, at least the outer layer
of the BNC tube is subjected to a compaction. Porosity of at least
the outer layer of the tube is decreased. By such measure, better
functionality of the implant could be observed, particularly a
better disconnection from body tissue that has been formed on the
outer layer. The implant of the invention may comprise an expanded
microbial cellulose tube, preferably in radial direction. The term
expanded means an expansion in comparison to a tube that is not
combined with a stent, for example a tube after its production and
optional storage in suitable liquid medium, such as deionized
water.
[0039] In one embodiment, the microbial cellulose tube is expanded
by the stent in radial direction. An expansion in radial direction
means that at least the inner diameter of the tube is increased,
and preferably that the inner and the outer diameter of the tube
are increased. The expansion can be in one or more radial
directions. The tube can be expanded in at least one radial
direction, preferably in more radial directions, even more
preferably in a multitude of radial directions or even each radial
direction. The diameter can be increased in at least one radial
direction, preferably in more radial directions, even more
preferably in a multitude of radial directions or even each radial
direction. The tube can be symmetrically or asymmetrically
expanded, in relation to its longitudinal axis, or in relation to a
distinct position or point at the longitudinal axis. The tube can
be expanded in radial direction at one or more positions along the
longitudinal axis of the tube, preferably a multitude of positions.
Most preferably, the tube is radially expanded over most of its
length or its whole length.
[0040] The tube and the stent may be linear or curved, or have one
or more bends. A linear tube is also called hollow cylinder.
[0041] The following description is directed to the tube of
microbial cellulose, its structure and methods for production. For
these subject matters it is explicitly referred to patent
application WO2013/113675A1 and its whole disclosure, which is
incorporated by reference in this description.
[0042] The term "microbial cellulose" means a cellulose which is
produced by a microorganism. Exemplary microorganisms are fungi,
bacteria and algae. A number of microorganisms is able to produce
microbial cellulose. These include, but are not limited to, algae
such as Valonia and Boergesenia, fungi such as Dictyostelium
discoideum and bacteria such as Gluconacetobacter
(Komagataeibacter), Enterobacter, Agrobacterium, Sarcina,
Pseudomonas, Rhizobium and Zoogloea. Examples of species
Acetobacter xylinum Gluconacetobacter, Acetobacter pasturianus,
Acetobacter aceti, Acetobacter ransens. A particularly useful
microorganism is Gluconacetobacter, particularly Gluconacetobacter
xylinus.
[0043] The layers of microbial cellulose in the tube are preferably
made of a network of fibers.
[0044] Microbial cellulose may be produced by microorganisms at the
interface between air and a nutrient medium in the form of a
biofilm (fleece). The bacteria produce the cellulose in form of
fibrils. These self-assemble into fibers. Through the interweaving
of the fibers, a three-dimensional, highly hydrous nanofiber
network of approximately 99% water and 1% cellulose is created
(Jonas R, Farah L F: Production and application of microbial
cellulose., Polym. Degrad. Staff (1998), 59 (1-3), 101-106; A
Hirai, Horii F: Cellulose Assemblies produced by Acetobacter
xylinum. ICR Annual Report (1999) 6, 28-29; Terminal D, Heublein B,
Fink HP, Bohn A: Cellulose: Fascinating Biopolymer as sustainable
raw material, Angew. Chem. Int. Ed. (2005) 44, 3358-3393).
[0045] Microbial cellulose is, if it is produced by bacteria, also
named herein as "bacterial cellulose", "bacterial nanocellulose"
(BNC) or simply "nanocellulose". The term "bacterial nanocellulose"
is derived from the fact that bacterially produced cellulose, as
mentioned above, forms a nanofiber network.
[0046] In one embodiment, the microbial cellulose tube, comprising
several layers of microbial cellulose is obtainable by or obtained
by a method comprising following steps: [0047] a) contacting the
surface of a template which is a negative mold of a cavity of the
microbial cellulose tube and of the inner walls of the cavity, with
a stock mixture comprising a liquid culture medium and a
cellulose-producing microorganism, [0048] b) interrupting of the
contact between the template and the stock mixture, wherein on the
surface of the template, a liquid film remains comprising the
liquid culture medium and the microorganism [0049] c) contacting of
the liquid film with an oxygen-containing atmosphere and formation
of microbial cellulose in and/or on the liquid film, [0050] d)
contacting the microbial cellulose obtained in step c) with the
stock mixture, [0051] e) interrupting the contact between the
microbial cellulose and the stock mixture wherein on the surface of
the microbial cellulose is a film of liquid is left, which
comprises the liquid culture medium and the microorganism, [0052]
f) contacting the liquid film with an oxygen-containing atmosphere
and formation of microbial cellulose in and/or on the liquid film,
wherein the sequence of steps d), e) and f) is repeated one or more
times, [0053] g) separating the microbial cellulose from the
template.
[0054] With this method, a tube composed of multiple distinct
layers of microbial cellulose can be produced.
[0055] In one embodiment, the microbial cellulose tube, singly or
as part of an implant of the invention, can show one or more of
features, singly or in any combination: [0056] a length of 10-200
mm, preferably 20-180 mm, more preferably 50-150 mm, [0057] an
inner diameter of 2-10 mm, preferably 2-8 mm, [0058] an outer
diameter of 3-15 mm, preferably 4-10 mm, [0059] a wall thickness of
1-5 mm, preferably 1-3 mm, [0060] a number of distinct BNC layers
of 3-10, preferably 5-10.
[0061] The culture medium, also referred to as a "broth" or "broth"
may contain conventional ingredients for culturing a cellulose
producing microorganism such as glucose, peptone, yeast extract,
sodium hydrogen phosphate and citric acid in aqueous solution
(Hestrin Schramm medium). An alternative acidic medium consists of
an aqueous solution of glucose, peptone, yeast, acetic acid and
ethanol.
[0062] The method is preferably carried out at a temperature of 20
to 40.degree. C.
[0063] In the method for producing the tube cultivation is carried
out not purely static. The template and stock mixture containing
culture solution and microorganism are moved relative to each other
so that the surface of the template is wetted. A permanent contact
of the template with the mixture stock is excluded. The template
and the mixture reservoir, having the culture medium and the
microorganism can be moved relative to each other, thereby
temporarily, but not permanently brought into contact. Feature of
the method is a template that is periodically, but not permanently,
brought into contact with culture solution and microorganism, the
formation of a film containing the culture medium and the
microorganism on the template and the biosynthesis of cellulose in
the template only in and/or on the film--outside of the stock
mixture.
[0064] The term "interrupting contact" means that the contact
between the template and mixture stock is so interrupting that no
part of the surface of the template during the interruption has
contact with the mixture stock.
[0065] In the method, the shape of the interior, or the inner
contour, of the tube is defined by a suitably shaped template, on
whose surface in carrying out the method, a liquid film is formed,
in which the biosynthesis of cellulose happens. Thus, the cellulose
produced directly on the template surface later forms the inner
surface of the tube. A first layer of cellulose is formed on the
template. Further layers are formed by steps d), e), f) and their
repetition. Steps b) and c) can be a combined step. Steps e) and f)
can be a combined step. The outer shaping of the hollow body
according to the invention is carried out without contact, only
through the influence of gravity. After wetting process, the wetted
template is free in the surrounding oxygen-containing atmosphere
and the cellulose-forming process is performed in and/or on the
film. The outer shape of the hollow body is defined solely by the
choice of culture conditions. The culture conditions include, for
example, the direction of the force of gravity, the frequency and
spacing of individual turns, the time interval between the wetting
time, the residence time, as explained below, the temperature and
the cultivation time.
[0066] The method for producing the tube can be carried out in the
apparatus described in WO2013/113675A1.
[0067] BNC-tubes produced by the method are characterized by
improved mechanical properties and bioactive surfaces. So, on a
bioactive outer surface body tissue, particulary bile duct
epithelium can be generated.
[0068] Length and internal diameter of the tube are variable and
variably combined. Exemplary internal diameters are 1-30 mm,
preferably 2-8 mm, and exemplary lengths are 5 to 500 mm,
preferably 100-200 mm. The length to diameter ratio is preferably
greater than 1. The inner diameter can also vary within a tube.
[0069] The tube, particularly its cavity, may also have a
differently shaped cross-section, for example a square,
rectangular, triangular or star-shaped cross-section instead of a
round.
[0070] The template is, as already mentioned, the negative mold of
the cavity of the tube and the inner wall of the tube. The term
"negative mold" refers to the tool, the male mold is the desired
result, in this case, the tube/void/tube wall. The template is
shaped complementary to the shape of the desired cavity produced
and is specified accordingly. Accordingly, the shape of the
template is defined by the shape of the above-mentioned hollow
body. The template sets the internal geometry of the hollow body.
For example, the template is cylindrical, with a diameter of 1-30
mm, preferably 2-8 mm, and a length of 5-500 mm, preferably 100-200
mm. As the tube cavity, the template may have an arbitrary
cross-section, such as round, rectangular, in particular square,
rectangular, triangular, or star-shaped or snowflake-shaped.
[0071] In one embodiment, the template has a surface having the
structures in the millimeter, micrometer and/or nanometer scale.
The structures are, for example, protrusions or depressions or
both. The structures may have different geometries.
[0072] The material from which the surface of the template is made
from is in principle not limited. In one embodiment, the template
has a surface made of wood, metal, such as aluminum, stainless
steel or titanium, plastics, ceramics, synthetic polymers such as
polypropylene, polyesters, polyamides or Teflon, paper or glass
fabric. The template material can be used pure or surface-coated in
a proper manner. It can also be the entire template from one of the
mentioned substances exist.
[0073] In a specific embodiment, an arrangement of a plurality of
templates is employed in the process, also referred to as template
matrix. It can templates with the same or different geometry, in
particular different cross-sections, and/or be used of the same or
different material. Thereby several identical or different tubes
can be obtained in the method. An example of an arrangement of a
plurality of templates is an arrangement of a plurality of
cylindrical templates for the production of several tubes. Multiple
templates of the same or different geometry can be fixed in a jig
(template array).
[0074] In the method the template is periodically, preferably for a
short time, wetted with the mixture comprising the culture broth
and the microorganism. Here, a liquid film forms on the surface of
the template. The shape of this liquid film is determined by the
position of the template in the room, because the gravity acts on
this film.
[0075] On the surface of the template, a liquid film is formed,
comprising the liquid culture medium and the microorganism. In
and/or on the liquid film microbial cellulose is formed. The liquid
film can be distributed on the template by the template is rotated
about one or more spatial axes, for example X, Y and/or Z in a
Cartesian coordinate system. This is explained in the examples of
WO2013/113675A1 by means of the movement device. By a predetermined
movement of the template even better distribution of the liquid is
achieved on the surface of the template. The distribution of the
liquid can be influenced by the type of the predetermined
rotational movement of the template, wherein the rotational
movement can also be interrupted. The external geometry of the tube
is thus determined by a defined distribution of liquid film and by
a defined movement under the influence of gravity.
[0076] Preferably, the template has a geometry with a length to
diameter ratio of greater than 1. For example, the template may
have a cylindrical geometry with a length to diameter ratio of
greater than 1, for producing a straight tube. The template has a
longitudinal axis. In particular, the tube is a hollow cylinder
with a central axis which runs centrally and longitudinally of the
cylinder expansion through the cavity. The process is then
preferably carried out so that the template is rotated about one or
more axes in space.
[0077] As mentioned, a liquid film is formed on the surface of the
template. The liquid film is formed when the template and the
mixture comprising the culture medium and the microorganism are
moved relative to each other and are thereby brought into
contact.
[0078] In one embodiment contacting the surface of a template with
the mixture is done such that the template is dipped into in the
mixture comprising the culture medium and the microorganism.
Movement, particularly rotation, of the template in one or more of
spatial axes can be superimposed to the immersion an interruption
of the contact of the template to mixture.
[0079] The oxygen-containing atmosphere is preferably air or pure
oxygen or an oxygen-containing gas mixture. Microbial cellulose is
formed in and/or on the liquid film when it comes into contact with
oxygen.
[0080] Separation of template and tube:
[0081] For use in the implant of the invention, the tube, formed of
nanocellulose, is separated from the template.
[0082] The separation takes place for example in that the cellulose
formed is stripped from the template, or the template is removed in
another manner. For example, the cellulose is stripped from a
cylindrical template and the tube is obtained.
[0083] The template may be rotated, about one or more spatial axes,
at least during step c) and/or step f), or one or more of the steps
f), when the step f) is carried out several times. With this
measure, the shape and distribution of the liquid film and the
shape of the forming product can be influenced. In other words, the
template is coated with a defined liquid film, which in turn leads
to a defined shape of the forming product. The rotation can be done
during step a) and b) and/or during the steps d) and e).
[0084] This sequence of steps d) -f) are repeated one or more times
until a desired amount of cellulose is formed on the surface of the
template and the cellulose has reached a desired overall layer
thickness. The so-called total layer may be composed of several
individual layers or phases. A synthesis of other microbial
cellulose takes place on already formed cellulose.
[0085] The times of contacting the surface of a template (step a)
with a mixture reservoir and of contacting the microbial cellulose
generated in step c) with the mixture stock (step d) are referred
to as "wetting time". The time of contacting of the liquid film
with an oxygen-containing atmosphere (steps c and f) are referred
to as "residence time". Wetting times and residence times can be
controlled independently of each other. The residence time is in
one embodiment, 1-60 minutes, preferably 5-40 min.
[0086] The total cultivation time is preferably 1-7 days. The total
cultivation time corresponds to the total process time within which
all steps of the method are performed, such as turning, wetting and
other steps. The duration of the procedure determines the thickness
of the formed microbial cellulose on the template, which
corresponds to the wall thickness of the tube.
[0087] The tube produced by the method can be cleaned to remove
residues and components of the culture medium and microorganisms.
For cleaning, water, aqueous acidic or alkaline solution or an
organic solvent, or a combination, can be used.
[0088] The tubes obtained with the method can be used without
drying after a cleaning and sterilization process for producing an
implant of the invention.
[0089] Following description relates to the structure of the
microbial cellulose tube.
[0090] In the tube, preferably at least the outer surface or the
outer layer of the microbial cellulose tube is porous. Porosity can
be reached by producing the tube according to above-described
method. Porosity improved formation/generation of tissue on the
microbial cellulose.
[0091] In particular, the tube has a wall with an inner surface and
an outer surface, wherein the inner surface and outer surface have
an identical or similar cover by fibers of microbial cellulose per
unit area. As mentioned, BNC form fibers of more or less dense and
more or less porous networks. With methods of image analysis it is
possible to distinguish surface areas where there are fibers (in an
SEM image, for example, light) from surface areas where are no
fibers (gaps, in an SEM image, for example, darker) and to set such
areas in relation to the total area.
[0092] The coverage per unit area can then be expressed as
coverage=part of area section which is covered with fiber/total
area of area section
[0093] The coverage can be expressed as a percentage.
[0094] The term "similar" in this context means that coverage the
inner surface and the outer surface differ relative to one another
by a maximum of 20%, preferably at most 10%, most preferably at
most 5%.
[0095] The percentage of the difference between the values is
calculated as follows:
difference (%)=(number of larger value-number of smaller
value)/number of smaller value.times.100
[0096] A similar coverage as defined above represents a similar
porosity of the inner and outer surface, wherein the porosity with
respect to a surface is two-dimensionally defined as
porosity (two-dimensional)=Part of the observed area section not
covered with fibers/total area of the area section.
[0097] The area not covered with fibers may be referred to as
"open-pore surface" or "surface pores".
[0098] For the connection between coverage and two-dimensional
porosity applies:
Porosity+coverage=1, or expressed as a percentage: porosity
(%)+coverage (%)=100%.
[0099] In the coverage and porosity BNC fibers can be taken into
account, which are just outside of the assumed two-dimensional
inner/outer surface. In an electron micrograph a two-dimensional
representation of the outer or inner surface of the wall of the
hollow body is obtained. The pictured BNC fibers, however, are not
always but in a plane, because the surfaces can exhibit a certain
roughness and/or optionally BNC fibers imaged are lying out of
sight of the viewer behind the surface. It has been found that in
the hollow body according to the invention the outer surface of the
wall may be rougher than the inner surface. In determining the
coverage and porosity preferably all BNC fibers are also taken into
account that on a scanning electron micrograph (10,000 times
magnification) are visible and they are treated as if they were in
a plane, since the coverage/porosity is based on a on a unit
area.
[0100] Thus, the tube has a wall with an inner surface and an outer
surface, the inner surface and the outer surface having a similar
porosity, as defined above.
[0101] The term "similar" means with respect to the porosity, that
the two-dimensional porosity of the inner surface and the outer
surface differ relative to one another by a maximum of 20%,
preferably at most 10%, most preferably at most 5%.
[0102] The percentage of the difference between the values is
calculated as follows:
difference (%)=(number of larger value-number of smaller
value)/number of smaller value.times.100th
[0103] The tube has a wall with an inner surface and an outer
surface, wherein the wall comprises multiple layers of microbial
cellulose, which run parallel to the inner and outer surface of the
wall. These layers are hereinafter also referred to as "phases".
The layers correspond to the above "single layers or phases" of the
wall of the hollow body.
[0104] Preferably, the phases are in their density over the entire
thickness homogeneous, i.e. they have no density gradient.
[0105] The phases are preferably characterized by a uniform
(isotropic), well-branched fiber network. Number and strength of
the phases are controlled adjustable.
[0106] These phases do not have to be obtained by one single
process cycle of wetting/filming and subsequent cellulose formation
in or on the film. A phase can be formed by several such cycles.
The phases are visually distinguishable from each other by scanning
electron microscopy, for example, at 24.times. magnification. The
phases are made up of a network of fibers bacterial Nanocellulose,
wherein the fiber structures of the phases in the comparison of the
phases may be the same or different.
[0107] The invention also describes a tube whose wall is made of
layers, also referred as phases as described above, wherein one of
the layers comprises the inner surface, i.e. the cavity side
surface, and a further layer comprises the outer surface, wherein
these two layers have an identical or similar porosity. The
layer/phase comprising the inner surface of the wall is also
referred to as the "lumen-side layer/phase" or "cavity-side
layer/phase". The layer/phase comprising the outer surface of the
wall is also referred to as "outer-side layer/phase".
[0108] With respect to the spatially formed layers/phases, the
porosity is spatially defined as:
porosity (spatial, three-dimensional)=void volume/total volume
[0109] In the total volume, the volume of the entire layer/phase
may be used. But it is also possible to look at just a fraction of
the volume of the layer/phase and look at this volume part to the
purpose of measuring the porosity as "total". The term "similar"
means with respect to the spatial porosity that the porosity of the
lumen-side phase, and the porosity of the outside phase vary
relative to each other by at most 20%, preferably at most 10%, most
preferably at most 5%.
[0110] The percentage of the difference between the values is
calculated as follows:
difference (%)=(number of larger value-number of smaller
value)/number of smaller value.times.100th
[0111] An identical or similar three-dimensional porosity means
that the lumen-side layer/phase and the outside layer/phase have an
identical or similar density. Identical or similar
three-dimensional porosity, as defined above, means that the
lumen-side layer/phase and the outside layer/phase have an
identical or similar fiber density.
[0112] The density is preferably given as mass/volume and the fiber
density is specified as a number of fibers/volume.
[0113] For the volume the volume of the entire layer/phase may be
used.
[0114] However, it is also possible and preferable to consider only
a part of the volume of the layer/phase for determining the density
or the fiber density. The term "similar" means with respect to the
density and fiber density that the density/fiber density of the
lumen-side phase and the density/fiber density of the outside phase
relative to each other differ by not more than 20%, preferably at
most 10%, most preferably 5% in maximum.
[0115] The percentage of the difference between the values is
calculated as follows: difference
(%)=(number of larger value-number of smaller value)/number of
smaller value.times.100th
[0116] Preferably, one or more other phases are disposed between
the lumen-side phase and the outside phase. Particularly
preferably, these one or more further phases have an identical or
similar porosity, density, and fiber density as that of the
lumen-side phase and the outside phase.
[0117] In a further aspect, the invention is directed to a process
for producing a medical implant, comprising: [0118] producing a
microbial cellulose tube, comprising [0119] a) contacting the
surface of a template which is a negative mold of a cavity of the
microbial cellulose tube and of the inner walls of the cavity, with
a stock mixture comprising a liquid culture medium and a
cellulose-producing microorganism, [0120] b) interrupting of the
contact between the template and the stock mixture, wherein on the
surface of the template, a liquid film remains comprising the
liquid culture medium and the microorganism [0121] c) contacting of
the liquid film with an oxygen-containing atmosphere and formation
of microbial cellulose in and/or on the liquid film, [0122] d)
contacting the microbial cellulose obtained in step c) with the
stock mixture, [0123] e) interrupting the contact between the
microbial cellulose and the stock mixture wherein on the surface of
the microbial cellulose is a film of liquid is left, which
comprises the liquid culture medium and the microorganism, [0124]
f) contacting the liquid film with an oxygen-containing atmosphere
and formation of microbial cellulose in and/or on the liquid film,
wherein the sequence of steps d), e) and f) is repeated one or more
times, [0125] g) separating the microbial cellulose from the
template, [0126] introducing a stent, preferably a tubular stent,
into the microbial cellulose tube.
[0127] With such method, any implant as described before can be
produced. The method step of producing a microbial cellulose tube,
comprising sub-steps a)-g) have been described before.
[0128] Introducing a stent into the tube can be done by sliding the
stent into the interior/cavity of the tube.
[0129] The implant of the invention can be used for surgery or a
method of surgery. The implant can be used for surgery of gall
bladder, hepatobiliary malignancy surgery, bile duct and/or liver,
e.g. gall removal or liver transplantation. The implant can
particularly be used for repairing or regeneration of bile duct.
Further fields of use are the use as esophagus implant or urether
implant, particularly in case of esophagus or urether lesion.
[0130] So, the present invention is also related to a medical
implant as described herein, for use in surgery, or in a method of
surgery, of gall bladder, hepatobiliary malignancy surgery, bile
duct, esophagus, urether or liver.
[0131] So, the present invention is also related to a medical
implant as described herein, for use in repairing or regeneration,
or in a method of repairing or regeneration, of a bile duct, an
esophagus lesion or an urether lesion.
[0132] The invention will now be described with reference to
examples.
A) DESCRIPTION OF FIGURES
[0133] FIG. 1 BNC tube on a template, in a cross section
[0134] FIG. 2 A medical implant of the invention
[0135] FIG. 3 A medical implant of the invention which is inserted
into an animal's body in order to regenerate a bile duct
B) EXAMPLE 1
Preparation of an Implant
[0136] a) Preparation of BNC Tube:
[0137] A device and reactor as shown and described in FIG. 1 of
WO2013/113675A1 is used for preparation of a BNC tube. To prepare
the products, several rod shaped templates are arranged in a
clamping and inserted into the moving means of the device. The
reactor is then closed and sterilized. After sterilization of the
entire reactor the reservoir of the reactor is filled under sterile
conditions with a mixture of cellulose producing microorganisms and
separately sterilized culture solution filled.
[0138] Then, the engine of the device is started, and following
steps performed: [0139] dipping the templates into the mixture of
cellulose producing microorganisms and culture solution in the
reservoir, thereby contacting the surface of the templates [0140]
removing the templates from the reservoir, thereby interrupting of
the contact between the template and the mixture, wherein on the
surface of the template, a liquid film remains comprising the
liquid culture medium and the microorganism [0141] contacting of
the liquid films on templates with the oxygen-containing atmosphere
inside of the device and formation of microbial cellulose in and/or
on the liquid film. In this step, the templates are rotated around
at least two rotational axes, in order to reach a defined and
preferably equal distribution of the film
[0142] The above sequence of steps is repeated several times until
the BNC tube on the template has assumed a desired shape a desired
wall thickness of about 1-3 mm. The length and inner diameter of
each BNC tube is determined by the dimensions of the corresponding
rod-shaped template.
[0143] At the end of the process, the tubes are stripped from the
templates, purified and stored wet, preferably in deionized
water.
[0144] The BNC tube had a length of approximately 80-150 mm, an
inner diameter of approximately 2-4 mm and an outer diameter of
approximately 4-10 mm. The number of distinct BNC layers in the
tube is about 5-7.
[0145] An obtained BNC-tube 1 is shown in a cross section in FIG.
1. The BNC tube 1 is placed onto the template 8, which is a metal
rod. L is the longitudinal axis of the BNC tube 1. L extends in the
viewing direction. The BNC tube 1 is composed of three layers 5, 6,
7, wherein layer 5 is an inner layer, 6 a middle layer and 7 the
outer layer. More than the shown layer 6 between the outer layer 7
and the inner layer 5 can be present. The layers 5, 6, 7 are
concentric or substantially concentric to a longitudinal axis (L)
of the tube 1. The inner surface of the lumen of the BNC tube 1 is
designated as 3, and the outer surface is 4.
[0146] An exemplary layer structure in a Scanning electron
micrograph is shown in FIG. 3 of WO2013/113675A1.
[0147] The layers 5, 6, 7 of microbial cellulose are made of
fibers. Exemplary structures are shown in FIGS. 4, 5, and 6 of
WO2013/113675A1.
[0148] b) Combining BNC Tube and Stent
[0149] A biliary stent (8,5 Fr Biliary Drainage Tube Set/Olympus,
Tokyo, Japan) with a length of 50-120 mm, a diameter of 8.5 Fr was
slit into the tube until the stent protruded both ends of the BNC
tube in symmetrical manner.
[0150] The obtained implant 100 is shown in appended FIG. 2.
[0151] The microbial cellulose tube 1 comprises a wall 2 with the
inner surface 3 and the outer surface 4. The wall 2 is composed of
the BNC layers 5, 6, 7 that are shown in FIG. 1.
[0152] The tubular stent 9 is placed inside of the microbial
cellulose tube 1. The outer surface 10 of the stent contacts the
inner surface 3 of the microbial cellulose tube 1.
[0153] As shown in FIG. 2, the length l.sub.2 of the stent 9 is
longer than the length l.sub.1 of the BNC tube 1. The tubular stent
9 protrudes from the microbial cellulose tube at a first end 11 of
the microbial cellulose tube 1 and a second end 12 of the microbial
cellulose tube 1.
[0154] In the example of FIG. 2, the outer diameter of the stent 9
may be higher than the inner diameter of the BNC tube 1 (without
stent 9). I this case, the tube 1 is expanded in radial direction.
Exemplary directions of expansion are designated with arrows R. It
is to be understood that expansion will in this example occur also
in other radial directions, since the stent 9 and the tube 1 are
circular. A more or less symmetric expansion occurs, thereby
increasing the inner diameter of the tube 1.
C) EXAMPLE 2
Insertion of the Implant Into Animal to Regenerate a Bile Duct
Comparative Example
[0155] In a first experiment, only a BNC tube, without stent, was
used as an implant. Implantation was done after resection of a bile
duct segment in a pig, having a length of 3 cm. The BNC tube was
interposed after length adjustment in end-to-end manner using
6/0-Prolene sutures.
[0156] In a second experiment an implant as shown in FIG. 2 was
used. FIG. 3 shows the implant 100 in a pig in a schematic view.
Reference signs correspond to reference signs in FIG. 2, as far as
the implant 100 is concerned.
[0157] FIG. 3 shows a part of a pig's liver 13 with a first bile
duct section, or bile duct end, 14 and a part of the duodenum 15
with a second bile duct section, or bile duct end, 16. In the first
bile duct section 14, a first protruding part of the stent 9 was
introduced. In the second bile duct section 16, a second protruding
part of the stent 9 was introduced. The BNC tube 1 is placed
between the bile duct sections 14, 16. A connection between the BNC
tube 1 and the bile duct sections 14, 16 is made by sutures 17,
18.
[0158] After insertion of the implant 100 in a pig as shown in FIG.
3 the implant 100 was left for four or eight weeks in the animal.
Following results were obtained:
[0159] The BNC tube was still placed in the bile duct, i.e. between
the bile duct sections 14, 16 but was not grown together with the
bile duct sections 14, 16.
[0160] New bile duct epithelium was continuously formed on the
surface 4 of the BNC tube, as shown by histologic analysis. In
result, the bile duct sections 14, 16 were connected by new bile
duct epithelium. The anastomosis was sufficient, in a sense that an
anastomosis ring could be observed. No badly healed or insufficient
anastomosis were observed. The actual anastomosis was not existent
any more since the interponate, i.e. the BNC tube, was
repelled.
[0161] The implant 100, i.e. the BNC tube 1 and the stent 4 could
be removed from the bile duct sections 14, 16 and the newly created
bile duct epithelium. The stent 9 was removed through the duodenum
15. Thereby, the BNC tube 1 was also removed. The BNC tube 1
disassociated from the new bile duct epithelium which was grown on
its surface.
* * * * *