U.S. patent application number 13/606260 was filed with the patent office on 2013-05-02 for glucosamine materials.
This patent application is currently assigned to THE JOHNS HOPKINS UNIVERSITY. The applicant listed for this patent is Jennifer H. Elisseeff. Invention is credited to Jennifer H. Elisseeff.
Application Number | 20130109808 13/606260 |
Document ID | / |
Family ID | 36916801 |
Filed Date | 2013-05-02 |
United States Patent
Application |
20130109808 |
Kind Code |
A1 |
Elisseeff; Jennifer H. |
May 2, 2013 |
GLUCOSAMINE MATERIALS
Abstract
Polymers comprising glucosamine (GlcN) are used to make medical
devices. Examples include polyGlcN and carrier molecules containing
multiple GlcN residues.
Inventors: |
Elisseeff; Jennifer H.;
(Baltimore, MD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Elisseeff; Jennifer H. |
Baltimore |
MD |
US |
|
|
Assignee: |
THE JOHNS HOPKINS
UNIVERSITY
Baltimore
MD
|
Family ID: |
36916801 |
Appl. No.: |
13/606260 |
Filed: |
September 7, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12368636 |
Feb 10, 2009 |
8268950 |
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13606260 |
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11816600 |
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PCT/US2006/005748 |
Feb 17, 2006 |
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12368636 |
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60654151 |
Feb 18, 2005 |
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Current U.S.
Class: |
525/54.2 ;
526/238.23; 536/53 |
Current CPC
Class: |
A61L 27/20 20130101;
A61K 31/80 20130101; C08F 24/00 20130101; A61K 47/36 20130101; A61L
27/20 20130101; C08F 269/00 20130101; A61K 31/724 20130101; C08B
37/0006 20130101; C08L 5/00 20130101 |
Class at
Publication: |
525/54.2 ;
526/238.23; 536/53 |
International
Class: |
C08F 269/00 20060101
C08F269/00; C08B 37/00 20060101 C08B037/00; C08F 24/00 20060101
C08F024/00 |
Claims
1. A composition comprising a biodegradable polymer comprising a
plurality of glucosamine residues (GlcN).
2. The composition of claim 1, wherein said polymer is a
polyGlcN.
3. The composition of claim 1, wherein said polymer comprises a
biodegradable backbone.
4. The composition of claim 3, wherein said backbone is a naturally
occurring polymer.
5. The composition of claim 4, wherein said naturally occurring
polymer is a polypeptide.
6. The composition of claim 3, wherein said naturally occurring
polymer is a polysaccharide.
7. The composition of claim 6, wherein said naturally occurring
polysaccharide is chondroitin sulfate or hyaluronic acid.
8. The composition of claim 3, wherein said biodegradable backbone
is not a naturally occurring polymer.
9. The composition of claim 8, wherein said non-naturally occurring
polymer is polyethylene glycol or polyvinyl alcohol.
Description
BACKGROUND OF THE INVENTION
[0001] Hyaluronic acid derivatives have been described, U.S. Pat.
Nos. 6,699,471; 6,723,709; 5,502,081; 5,616,568; 5,502,081;
6,537,979; 6,294,202; 6,703,041; 6,610,669; 6,749,865; and
6,521,223. Many of those derivatives are used primarily to reduce
adhesions at sites of surgical intervention.
[0002] A chemically modified hyaluronic acid and
carboxymethylcellulose combination is commercially available in
film form (Seprafilm.TM., Genzyme), U.S. Pat. Nos. 4,937,270 and
5,017,229.
[0003] Generally, the hyaluronic acid derivatives have physical and
chemical properties that differ from the native compound, the
derivatives have higher residence time, generally owing to
increased viscosity, and can be manufactured into devices without
losing many of the biocompatible properties of the native compound.
Such modifications are required because hyaluronic acid is
characterized by a very rapid absorption. Nevertheless, hyaluronic
acid is attractive because the molecule is not covalently bound to
protein.
[0004] Kulkarni (U.S. Pat. No. 6,822,064) teaches polymerized
macromers containing, for example, N-acetylglucosamine (NAG). The
molecules of interest comprise a backbone molecule to which NAG,
among many other sugars, is covalently bound. The macromers bind to
and inactivate lysozyme. The macromers are stable and resistant to
degradation.
SUMMARY OF THE INVENTION
[0005] It is an object of the invention to provide compositions of
various forms for use as devices and vehicles in a body. The
compositions can be in liquid or solid form. Thus, an object is to
provide, for example, a replacement synovial fluid; a scaffold for
tissue engineering; a film for wound healing, shaping or for lining
or coating a surface; a form for drug delivery; a nutrient and so
on.
[0006] Those and other objects have been attained in the
development of polymeric glucosamine (GlcN) derivatives such as
polyGlcN, functionalized hyaluronic acid and biodegradable polymers
comprising a backbone to which plural GlcN residues are bound,
preferably by biologically labile bonds. Suitable biomolecules that
can be conjugated with GlcN include, for example, hyaluronic acid
and chondroitin sulfate.
[0007] In other embodiments, the GlcN residues are functionalized
as known in the art. For example, one or more of the hydroxyl
groups can be acetylated, for example, using acetic anhydride, to
yield acetylated GlcN residues. Other suitable functional groups
that can be added to the GlcN residue include carboxyl groups.
Also, the amine group of GlcN can be derivatized.
[0008] In other embodiments, the polyGlcN or biologically
compatible polymers carrying plural GlcN residues contain
biologically labile bonds so that the molecules are biodegradable.
That makes the monomers or oligomers of the polymer and the GlcN
residues, functionalized or not, biologically available.
[0009] Additional features and advantages of the present invention
are described in, and will be apparent from, the following Detailed
Description of the Invention and the figures.
BRIEF DESCRIPTION OF THE FIGURES
[0010] FIG. 1 depicts a synthetic scheme for making a polyGlcN
molecule.
[0011] FIG. 2 depicts an alternative scheme for making a polyGlcN
molecule. A GlcN is reacted with a glutamic anhydride compound.
[0012] FIGS. 3A and 3B depict a synthetic scheme for conjugating
GlcN onto chondroitin sulfate (CS). CS is derivatized to yield a
reactive site. One such means using the known reagent, glycidyl
methacrylate, and method is depicted in FIG. 3A. A reactive GlcN
derivative, for example, as made by either of the schemes depicted
in FIG. 1 or 2, can be reacted with the CSMA residue, FIG. 3B.
[0013] FIGS. 4A and 4B depict a synthetic scheme for derivatizing
hyaluronic acid (HA) with GlcN. In FIG. 4A, HA is derivatized.
Again, a reactive GlcN residue can be made by the schemes set forth
in FIG. 1 or 2, and reacted with the derivatized HA to conjugate
the two molecules, FIG. 4B.
DETAILED DESCRIPTION OF THE INVENTION
[0014] The invention relates to products and methods for making and
using GlcN molecules for a variety of uses, including structural,
supportive, nutritive, lubricative and so on.
[0015] The glucosamine molecules of interest can assume a variety
of forms depending on the degree of polymerization, degree of
bonding, the substituents attached to a glucosamine and the
molecules to which a glucosamine are attached.
[0016] In one embodiment, a molecule of interest is a polyGlcN
molecule. GlcN residues are linked to form a polymer using standard
chemistries. Thus, GlcN can be functionalized to produce monomers
suitable for polymerization. On exposure to a polymerizing
initiator, polyGlcN is formed.
[0017] A "polymerizing initiator" refers to any substance that can
initiate polymerization of monomers or polymers by, for example,
free radical generation. The polymerizing initiator often is an
oxidizing agent. Exemplary polymerizing initiators include those
which are activated by exposure to, for example, electromagnetic
radiation, such as UV light or heat.
[0018] In another embodiment, a molecule of interest comprises a
biological molecule or biocompatible molecule, a backbone molecule,
to which one or more GlcN residues are attached, preferably by
biologically labile linkages. Generally, the backbone molecule is a
polymer. Accordingly, each monomer can be derivatized with a GlcN
residue, every other monomer can contain a GlcN, and so on, as a
design choice. A molecule of interest contains plural GlcN
residues. The backbone molecule can be any biological molecule such
as a carbohydrate, a polynucleotide or a polypeptide. The GlcN is
bound to the backbone molecule, preferably by a chemical bond that
is biodegradable in situ. Suitable polymers include those that are
naturally occurring in synovial fluid, cartilaginous environments
and osseous environments. Suitable biomolecules that can serve as a
backbone include polysaccharides. Suitable polysaccharides include
hyaluronic acid and chondroitin sulfate, for example.
[0019] Alternatively, the backbone can be a heteropolymer of
glucosamine and another monomer, such as a hyaluronic acid
component or a chondroitin sulfate component. Such naturally
occurring polymers that are preferred are those which are
biodegradable. The GlcN residue is bound thereto using standard
chemistries.
[0020] The term "polymer" is used to refer to molecules composed of
repeating monomer units, including homopolymers, block copolymers,
heteropolymers, random copolymers, graft copolymers and so on.
Polymers also include linear polymers as well as branched polymers.
The branched polymers of interest are not highly branched, are not
generational polymers, known as dendrimers or starburst
polymers.
[0021] A "monomer" is the basic repeating unit in a polymer. A
monomer may itself be a monomer or may be dimer or oligomer of at
least two different monomers, and each dimer or oligomer is
repeated in a polymer.
[0022] The term "biologically compatible polymer" or
"biocompatible" refers to a naturally occurring polymer or one that
is not toxic to the host. Generally, the metabolites of the polymer
of interest also are not toxic to the host. It is not necessary
that any subject composition have a purity of 100% to be deemed
biocompatible; indeed, it is only necessary that the subject
compositions be non-toxic to the host. Hence, a subject composition
may comprise monomer, polymers or portions thereof comprising 99%,
98%, 97%, 96%, 95%, 90%, 85%, 80%, 75% or even less of
biocompatible monomer, polymers or portions thereof, e.g.,
including monomers, polymers or portions thereof, and other
materials and excipients described herein, and still be
biocompatible.
[0023] To determine whether a polymer or other material is
biocompatible, it may be necessary to conduct a toxicity analysis.
Such assays are well known in the art. One example of such an assay
may be performed with, for example, live carcinoma cells in the
following manner: a sample of the intact molecule or a sample
wherein the molecule is degraded in 1M NaOH at 37.degree. C. until
complete degradation is observed is used. The solution is then
neutralized with 1M HCl. About 200 pL of various concentrations of
the sample are placed in 96-well tissue culture plates and seeded
with human carcinoma cells at 10.sup.4/well density. The samples
are incubated with the cells for 48 hours. The results of the assay
may be plotted as % relative growth vs. concentration of sample in
the tissue culture well. In addition, monomers, polymers, polymer
structures and formulations of the present invention may also be
evaluated by well-known in vivo tests, such as subcutaneous
implantation in rats to confirm that they do not cause significant
levels of irritation or inflammation at the subcutaneous
implantation sites. Acceptable levels of toxicity are as known in
the art.
[0024] A GlcN molecule of interest is one that is not toxic to a
host, such as a mammal. Determining safety in a host is a well
known exercise in the food and drug arts, and includes, for
example, in vitro studies on cells and tissues, and perhaps,
organs, animal studies and early human clinical trials.
[0025] In some embodiments, the disclosure is directed to a
composition comprising a glycosaminoglycan, mucopolysaccharide,
collagen or proteoglycan component, such as hyaluronic acid,
heparin sulfate, glucosamines, dermatans, keratans, heparans,
hyalurunan, aggrecan and the like, or a saccharide, such as
hyaluronic acid, heparin sulfate, keratan sulfate and the like
serving as the backbone molecule. Those polysaccharides are natural
components of extracellular matrices of cells and tissues. However,
in general, any biologically compatible polymer can be used as the
polymer backbone.
[0026] Synthetic polymers that are biocompatible also can be used
in the practice of the instant invention. Examples of such
synthetic, biocompatible polymers are polyethylene glycol (PEG),
polyvinyl alcohol (PVA) and block copolymers, such as the
Pluronic.RTM. compounds.
[0027] Suitable polymers include biocompatible monomers with
recurring units found in poly(phosphoesters), poly(lactides),
poly(glycolides), poly(caprolactones), poly(anhydrides),
poly(amides), poly(urethanes), poly(esteramides),
poly(orthoesters), poly(dioxanones), poly(acetals), poly(ketals),
poly(carbonates), poly(orthocarbonates), poly(phosphazenes),
poly(hydroxybutyrates), poly(hydroxyl valerates), poly(alkylene
oxalates), poly(alkylene succinates), poly(malic acids), poly(amino
acids), poly(vinylpyrrolidone), poly(ethylene glycol),
poly(hydroxycellulose), chitin and chitosan, and copolymers,
terpolymers or combinations or mixtures of the above materials.
[0028] Other suitable synthetic polymers include polymers
containing amine groups, such as chemically synthesized
polypeptides. Such polypeptides may include polynucleophilic
polypeptides that have been synthesized to incorporate amino acids
containing primary amino groups for example, lysine and/or amino
acids containing thiol groups (such as cysteine). Further suitable
synthetic polymers include poly(amino)acids.
[0029] A GlcN derivative of interest can be configured to have
varying levels of biodegradability by the type and number of bonds
between monomers. Thus, very labile bonds can be used for a
composition destined for rapid degradation and more resistant bonds
can be used for compositions meant for a desired level of
permanence in a host. By being biodegradable, the GlcN residues,
functionalized or not, become biologically available.
[0030] By biodegradable is meant that the polymer or particular
bonds of the polymer are cleaved under normal physiological
processes in a mammal. Generally, the polymer degradation products
are non-toxic or biocompatible as well.
[0031] The term "biodegradable" is art-recognized and is intended
to indicate that an object degrades during use. In general,
degradation attributable to biodegradability involves the
degradation of a biodegradable polymer into oligomers or its
component subunits, or digestion, e.g., by a biochemical process,
of the polymer into smaller subunits. In certain embodiments, two
different types of biodegradation may generally be identified. For
example, one type of biodegradation may involve cleavage of bonds
(whether covalent or otherwise) in the polymer backbone. In such
biodegradation, monomers and oligomers typically result, and even
more typically, such biodegradation occurs by cleavage of a bond
connecting one or more of subunits of a polymer. In contrast,
another type of biodegradation may involve cleavage of a bond
(whether covalent or otherwise) internal to a side chain or that
connects a side chain to the polymer backbone. The side chain is
one that contains GlcN. Alternatively, a therapeutic agent,
biologically active agent or other chemical moiety attached as a
side chain to a polyGlcN may be released by biodegradation. In
certain embodiments, one or the other or both general types of
biodegradation may occur during use of a polymer of interest. As
used herein, the term "biodegradation" encompasses both general
types of biodegradation as the overall desired function of the
functionalized polymer of interest wanes.
[0032] The degradation rate of a biodegradable polymer often
depends in part on a variety of factors, including the chemical
identity of linkages; the molecular weight, crystallinity,
biostability and degree of cross-linking of such polymer; the
physical characteristics of the implant, such as the shape and
size; the mode and location of administration; and so on. For
example, the greater the molecular weight, the higher the degree of
crystallinity, and/or the greater the biostability, the
biodegradation of any biodegradable polymer is usually slower. The
term "biodegradable" is intended to cover materials and processes
also termed "bioerodible". Generally, the rate of degradation is a
design choice based on the monomers, functional groups, added
ingredients and the like that are used.
[0033] In certain embodiments, the biodegradation rate of such
polymer may be characterized by the presence of enzymes, for
example, a particular protease, lipase, saccharidase and so on. In
such circumstances, the biodegradation rate may depend on not only
the chemical identity and physical characteristics of the polymer
matrix, but also on the identity, use, presence and the like of any
such enzyme.
[0034] Thus, a GlcN molecule of interest can be one that releases
GlcN residues thereby making the GlcN molecule bioavailable, but
also one that releases monomers or oligomers of the backbone
molecule. GlcN is a naturally occurring molecule and has nutritive
and effector functions. GlcN, for example, is compatible and
promotes stem cell growth and differentiation, for example, of
mesenchymal stem cells to form chondrocytes. GlcN can have a role
in tissue development and repair, such as cartilage growth and
development, in general. Therefore, placing a GlcN composition of
interest into a bone or cartilage defect, whether arising by normal
wear and tear, from an injury or purposely to stimulate repair,
such as by microfracture, can serve not only a structural role by
filling the defect and providing structural support, but also a
nutritive role by stimulating stem cell differentiation, and by
stimulating bone and cartilage growth. A composition that provides
a 1 mM to about a 10 mM local concentration of GlcN is beneficial.
Other concentrations, such as 2-5 mM can be advantageous. An
artisan can determine a suitable local concentration of GlcN
practicing methods known in the pharmaceutic arts, and that
determination will govern the nature and composition of the GlcN
composition of interest to obtain the desired concentration of
GlcN.
[0035] GlcN monomers and biodegradable polymers of GlcN, which
contain GlcN or which release GlcN, may be incorporated into other
matrices, such as hydrogels, fibers, scaffolds, depots, prostheses,
nanofibers and other structures, for release from the matrix in a
fashion and at a rate determinable as a design choice depending on,
for example, matrix pore size, ionic interactions between GlcN and
the matrix, degree of polymerization of a GlcN polymer, degree of
derivatization of a GlcN or matrix and so on. Generally, the
biomaterial, such as a scaffold, is one that is biodegradable.
Nanomaterials, such as nanotubes and nanofibers, can be
incorporated into such scaffolds and other matrices, or may
comprise the matrix per se. See for example, WO 2005/123903.
[0036] A GlcN molecule of interest, whether a monomer of part of a
polymer, may be functionalized to contain reactive groups. That
enables a GlcN molecule of interest to be covalently attached to a
matrix, tissue and the like, or enables a GlcN molecule of interest
to contribute to a biomaterial. Thus a functionalized GlcN molecule
of interest can react with a functionalized-polymer or
functionalized hydro gel.
[0037] A reactive moiety includes any moiety that reacts with a
suitable element, chemical group or chemical site on a target
entity. One set of target entities are biological structures, such
as cells, tissues, organs and the like. A functional group on the
biologically compatible polymer reactive with a biological surface
moiety includes any functional group that reacts with a suitable
element, chemical group or chemical site on a surface of a
biological structure, such as a cell, tissue, organ and the like.
Thus, a suitable element, chemical group or chemical site on the
surface of a biological structure would be a reactive group found
in, for example, a carbohydrate, an amino acid or a nucleic acid,
such as an amine group, a carboxylic acid group, a hydroxyl group,
a sulfate group and so on. Accordingly, a suitable reactive moiety
would be one that reacts with an amine group, a hydroxyl group and
so on of the surface of a biological structure. A suitable
functional group would be one that reacts with an amine group, a
hydroxyl group and so on of the surface of a biological structure.
Another example is an aldehyde group.
[0038] Other reactive moieties are those which react with elements,
chemical groups or chemical sites on biologically compatible
materials, such as implants, prostheses, other devices and the
like.
[0039] Other functional groups on the biologically compatible
polymer are those which react with elements, chemical groups or
chemical sites on a bridging molecule.
[0040] A reactive moiety or functional group (which terms, for the
purposes of the invention, are considered equivalent) may include
alkenyl moieties such as acrylates, methacrylates, dimethacrylates,
oligoacrylates, oligomethacrylates, ethacrylates, itaconates or
acrylamides. Further reactive moieties include carboxylates and
aldehydes. Other reactive moieties may include ethylenically
unsaturated monomers including, for example, alkyl esters of
acrylic or methacrylic acid such as methyl methacrylate, ethyl
methacrylate, butyl methacrylate, ethyl acrylate, butyl acrylate,
hexyl acrylate, n-octyl acrylate, lauryl methacrylate, 2-ethylhexyl
methacrylate, nonyl acrylate, benzyl methacrylate, the hydroxyalkyl
esters of the same acids such as 2-hydroxyethyl acrylate,
2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate, the
nitrile and amides of the same acids such as acrylonitrile,
methacrylonitrile, methacrylamide, vinyl acetate, vinyl propionate,
vinylidene chloride, vinyl chloride, and vinyl aromatic compounds
such as styrene, t-butyl styrene and vinyl toluene, dialkyl
maleates, dialkyl itaconates, dialkyl methylene malonates, isoprene
and butadiene. Suitable ethylenically unsaturated monomers
containing carboxylic acid groups include acrylic monomers such as
acrylic acid, methacrylic acid, ethacrylic acid, itaconic acid,
maleic acid, fumaric acid, monoalkyl itaconate including monomethyl
itaconate, monoethyl itaconate, and monobutyl itaconate, monoalkyl
maleate including monomethyl maleate, monoethyl maleate, and
monobutyl maleate, citraconic acid and styrene carboxylic acid.
Suitable polyethylenically unsaturated monomers include butadiene,
isoprene, allylmethacrylate, diacrylates of alkyl diols such as
butanediol diacrylate and hexanediol diacrylate, divinyl benzene
and the like.
[0041] In some embodiments, a monomer of a biologically compatible
polymer may be functionalized through one or more thio, carboxylic
acid or alcohol moiety located on a monomer of the biopolymer.
[0042] The reactive moieties or functional groups are attached to
the monomer or biologically compatible polymer using known
chemistries based on design choice.
[0043] Thus, in producing, for example, a functionalized
saccharide, a solution comprising the saccharide and a first
functional group reactant, such as an alkylene or an acrylate
group, are mixed. The solution is stirred, for example, for at
least 10 days, at least 11 days or at least 15 days. Alternatively,
the solution may be stirred or maintained for about 10 to about 15
days or about 14 to about 15 days. The solution may include a polar
solvent, for example an aqueous solvent.
[0044] For example, methacrylic anhydride, methacryloyl chloride
and glycidyl methacrylate may be used to add methacrylate groups to
one or more monomers of a polymer chain. Glycidyl methacrylate may
be used, for example, for efficiency of reaction. Further, the
modification reagents may be chosen to optimize for a lack of
cytotoxic byproducts.
[0045] A suitable method for making a polymer with aldehyde groups
is to treat a molecule with adjacent hydroxyl groups, such as
chondroitin sulfate, with a periodate salt, as known in the
art.
[0046] The term "functionalized" refers to a modification of an
existing molecular entity, structure or site to generate or to
introduce a new reactive or more reactive group, such as an acetyl
group or a group (e.g., acrylate group) that is capable of
undergoing reaction with another functional group (e.g., a
sulfhydryl group) to form, for example, a covalent bond. For
example, carboxylic acid groups can be functionalized by reaction
with an acyl halide, e.g., an acyl chloride, again, using known
procedures, to provide a new reactive functional group in the form
of an anhydride.
[0047] The term "aliphatic" is an art-recognized term and includes
linear, branched and cyclic alkanes, alkenes or alkynes. In certain
embodiments, aliphatic groups in the present invention are linear
or branched and have from 1 to about 20 carbon atoms, or more.
[0048] The term "alkyl" is art-recognized and includes saturated
aliphatic groups, including straight-chain alkyl groups,
branched-chain alkyl groups, cycloalkyl (alicyclic) groups, alkyl
substituted cycloalkyl groups and cycloalkyl substituted alkyl
groups. In certain embodiments, a straight chain or branched chain
alkyl has about 30 or fewer carbon atoms in its backbone (e.g.,
C.sub.1-C.sub.30 for straight chain and C.sub.3-C.sub.30 for
branched chain), and alternatively, about 20 or fewer carbon atoms.
Likewise, cycloalkyls have from about 3 to about 10 carbon atoms in
their ring structure, and alternatively, about 5, 6 or 7 carbons in
the ring structure.
[0049] Moreover, the term "alkyl" (or "lower alkyl") includes both
"unsubstituted alkyls" and "substituted alkyls", the latter of
which refers to alkyl moieties having substituents replacing a
hydrogen on one or more carbons of the hydrocarbon backbone. Such
substituents may include, for example, a halogen, a hydroxyl, a
carbonyl (such as a carboxyl, an alkoxycarbonyl, a formyl or an
acyl), a thiocarbonyl (such as a thioester, a thioacetate or a
thioformate), an alkoxyl, a phosphoryl, a phosphonate, a
phosphinate, an amino, an amido, an amidine, an imine, a cyano, a
nitro, an azido, a sulfhydryl, an alkylthio, a sulfate, a
sulfonate, a sulfamoyl, a sulfonamido, a sulfonyl, a heterocyclyl,
an aralkyl, or an aromatic or heteroaromatic moiety. It will be
understood by those skilled in the art that the moieties
substituted on the hydrocarbon chain may themselves be substituted,
if appropriate. For instance, the substituents of a substituted
alkyl may include substituted and unsubstituted forms of amino,
azido, imino, amido, phosphoryl (including phosphonate and
phosphinate), sulfonyl (including sulfate, sulfonamido, sulfamoyl
and sulfonate) and silyl groups, as well as ethers, alkylthios,
carbonyls (including ketones, aldehydes, carboxylates and esters),
--CF.sub.3, --CN and the like. Exemplary substituted alkyls are
described below. Cycloalkyls may be further substituted with
alkyls, alkenyls, alkoxys, alkylthios, aminoalkyls,
carbonyl-substituted alkyls, --CF.sub.3, --CN and the like.
[0050] The term "aralkyl" is art-recognized and includes aryl
groups (e.g., an aromatic or heteroaromatic group).
[0051] The terms "alkenyl" and "alkynyl" are art-recognized and
include unsaturated aliphatic groups analogous in length and
possible substitution of the alkyls described above, but that
contain at least one double or triple bond, respectively.
[0052] Unless the number of carbons is otherwise specified, "lower
alkyl" refers to an alkyl group, as defined above, but having from
one to ten carbons, alternatively, from one to about six carbon
atoms in the backbone structure. Likewise, "lower alkenyl" and
"lower alkynyl" have similar chain lengths.
[0053] A "methacrylate" refers to a vinylic carboxylate, for
example, a methacrylic acid in which the acidic hydrogen has been
replaced. Representative methacrylic acids include acrylic,
methacrylic, chloro acrylic, cyano acrylic, ethylacrylic, maleic,
fumaric, itaconic and half esters of the latter dicarboxylic
acids.
[0054] The term "heteroatom" is art-recognized and in an organic
molecule, generally includes an atom of any element other than
carbon or hydrogen. Illustrative heteroatoms include boron,
nitrogen, oxygen, phosphorus, sulfur and selenium.
[0055] The term "aryl" is art-recognized and includes, for example,
5-, 6- and 7-membered single ring aromatic groups that may include
from zero to four heteroatoms, for example, benzene, pyrrole,
furan, thiophene, imidazole, oxazole, thiazole, triazole, pyrazole,
pyridine, pyrazine, pyridazine, pyrimidine and the like. Those aryl
groups having heteroatoms in the ring structure may also be
referred to as "aryl heterocycles" or "heteroaromatics." The
aromatic ring may be substituted at one or more ring positions with
such substituents as described above, for example, halogen, azide,
alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, alkoxyl,
amino, nitro, sulfhydryl, imino, amido, phosphonate, phosphinate,
carbonyl, carboxyl, silyl, ether, alkylthio, sulfonyl, sulfonamido,
ketone, aldehyde, ester, heterocyclyl, aromatic or heteroaromatic
moieties, --CF.sub.3, --CN or the like. The term "aryl" also
includes polycyclic ring systems having two or more cyclic rings in
which two or more carbons are common to two adjoining rings (the
rings are "fused rings") wherein at least one of the rings is
aromatic, e.g., the other cyclic rings may be cycloalkyls,
cycloalkenyls, cycloalkynyls, aryls and/or heterocyclyls, or rings
joined by non-cyclic moieties.
[0056] The terms "ortho", "meta" and "para" are art-recognized and
apply to 1,2-, 1,3- and 1,4- disubstituted benzenes, respectively.
For example, the names 1,2-dimethylbenzene and
ortho-dimethylbenzene are synonymous.
[0057] The terms "heterocyclyl" and "heterocyclic group" are
art-recognized and include 3- to about 10-membered ring structures,
such as 3- to about 7-membered rings, whose ring structures include
one to four heteroatoms. Heterocycles may also be polycycles.
Heterocyclyl groups include, for example, thiophene, thianthrene,
furan, pyran, isobenzofuran, chromene, xanthene, phenoxanthin,
pyrrole, imidazole, pyrazole, isothiazole, isoxazole, pyridine,
pyrazine, pyrimidine, pyridazine, indolizine, isoindole, indole,
indazole, purine, quinolizine, isoquinoline, quinoline,
phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline,
pteridine, carbazole, carboline, phenanthridine, acridine,
pyrimidine, phenanthroline, phenazine, phenarsazine, phenothiazine,
furazan, phenoxazine, pyrrolidine, oxolane, thiolane, oxazole,
piperidine, piperazine, morpholine, lactones, lactams, such as
azetidinones and pyrrolidinones, sultams, sultones and the like.
The heterocyclic ring may be substituted at one or more positions
with such substituents as described above, as for example, halogen,
alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, amino,
nitro, sulfhydryl, imino, amido, phosphonate, phosphinate,
carbonyl, carboxyl, silyl, ether, alkylthio, sulfonyl, ketone,
aldehyde, ester, a heterocyclyl, an aromatic or heteroaromatic
moiety, --CF.sub.3, --CN or the like.
[0058] The terms "polycyclyl" and "polycyclic group" are
art-recognized and include structures with two or more rings (e.g.,
cycloalkyls, cycloalkenyls, cycloalkynyls, aryls and/or
heterocyclyls) in which two or more carbons are common to two
adjoining rings, .e.g., the rings are "fused rings". Rings that are
joined through non-adjacent atoms, e.g., three or more atoms are
common to both rings, are termed "bridged" rings. Each of the rings
of the polycycle may be substituted with such substituents as
described above, as for example, halogen, alkyl, aralkyl, alkenyl,
alkynyl, cycloalkyl, hydroxyl, amino, nitro, sulfhydryl, imino,
amido, phosphonate, phosphinate, carbonyl, carboxyl, silyl, ether,
alkylthio, sulfonyl, ketone, aldehyde, ester, a heterocyclyl, an
aromatic or heteroaromatic moiety, --CF.sub.3, --CN or the
like.
[0059] The following art-recognized terms have the following
meanings: "nitro" means --NO.sub.2; the term "halogen" designates
--F, --Cl, --Br or --I; the term "sulfhydryl" means --SH; the term
"hydroxyl" or "hydroxy" means --OH; and the term "sulfonyl" means
--SO.sub.2--.
[0060] The terms "amine" and "amino" are art-recognized and include
both unsubstituted and substituted amines, as well as primary,
secondary tertiary amines, which may be functionalized. The term
"alkylamine" includes an amine group, as defined above, having a
substituted or unsubstituted alkyl attached thereto. The term
"acylamino" is art-recognized and includes a amine having a
substituted or unsubstituted acyl group attached thereto. The term
"amido" is art-recognized as an amino-substituted carbonyl. In
certain embodiments, the amide will not include imides which may be
unstable
[0061] Certain monomeric subunits of the present invention may
exist in particular geometric or stereoisomeric fauns. In addition,
polymers and other compositions of the present invention may also
be optically active. The present invention contemplates all such
compounds, including cis and trans isomers, R and S enantiomers,
diastereomers, d isomers, l isomers, the racemic mixtures thereof,
and other mixtures thereof, as falling within the scope of the
invention. Additional asymmetric carbon atoms may be present in a
substituent, such as an alkyl group. All such isomers, as well as
mixtures thereof, are intended to be included in this
invention.
[0062] If, for instance, a particular enantiomer of a compound of
the present invention is desired, it may be prepared by asymmetric
synthesis, or by derivation with a chiral auxiliary, where the
resulting diastereomeric mixture is separated and the auxiliary
group cleaved to provide the pure desired enantiomers.
Alternatively, where the molecule contains a basic functional
group, such as amino or an acidic functional group, such as
carboxyl, diastereomeric salts are formed with an appropriate
optically active acid or base, followed by resolution of the
diastereomers thus formed by fractional crystallization or
chromatographic means well known in the art, and subsequent
recovery of the pure enantiomers.
[0063] It will be understood that "substitution" or "substituted
with" includes the implicit proviso that such substitution is in
accordance with the permitted valency of the substituted atom and
the substituent, and that the substitution results in a stable
compound, e.g., which does not spontaneously undergo
transformation, such as by rearrangement, cyclization, elimination
or other reaction.
[0064] The term "substituted" is also contemplated to include all
permissible substituents of organic compounds. In a broad aspect,
the permissible substituents include acyclic and cyclic, branched
and unbranched, carbocyclic and heterocyclic, and aromatic and
non-aromatic substituents of organic compounds. Illustrative
substituents include, for example, those described hereinabove. The
permissible substituents may be one or more and the same or
different for appropriate organic compounds. For purposes of this
invention, the heteroatoms such as nitrogen may have hydrogen
substituents and/or any permissible substituents of organic
compounds described herein which satisfy the valences of the
heteroatoms. This invention is not intended to be limited in any
manner by the permissible substituents of organic compounds.
[0065] For purposes of this invention, the chemical elements are
identified in accordance with the Periodic Table of the Elements,
CAS version, Handbook of Chemistry and Physics, 67th Ed., 1986-87,
inside cover.
[0066] In some embodiments, the number of the reactive moieties per
polymeric unit may be at least one moiety per about 10 monomeric
units, or at least about 2 moieties per about 10 monomeric units.
Alternatively, the number of reactive moieties per polymeric unit
may be at least one moiety per about 12 monomeric units, or per
about 14 monomeric units. For example, there may be at least about
one reactive moiety per 15 or more monomeric units. The number of
moieties also can range from one per monomer, one per two monomers,
one per three monomers, one per 4, 5, 6, 7, 8 or 9 monomers.
[0067] Also, a polymer of interest may contain plural species of
reactive moieties to provide a directionality to the polymer. When,
for example, a polymer contains two species of reactive moieties,
the ratio of one of the two reactive moieties to the other can be
5:1, 9:2, 4:1, 7:2, 3:1, 5:2, 2:1, 3:2, 1:1, 2:3, 1:2, 2:5, 1:3,
2:7, 1:4, 2:9 or 1:5 along the full length of the polymer.
Preferably, each of the functional moieties is regularly
distributed along the length of the polymer and in substantially
equal molar amounts. However, the amount of any one reactive moiety
type is optimized for reaction with the intended target entity and
may result in amounts where the ratio of the two types of reactive
moieties deviates from unity.
[0068] For example, poly(ethylene oxide)-diacrylate (PEODA) may be
used, and cross-linked polymer matrices may include cogels of an
acrylated GlcN and PEODA. The cogels formed thereby will have
properties different from that of the two parent compounds, and
properties of the cogel will vary based on the ratio of the two
reactants. Examples of derivatized hydrogels can be found in WO
2004/029137.
[0069] The mechanical properties of a polymer or a multi-layer
polymer, such as a scaffold, may also be related to the pore
structure. For applications in tissue engineering, scaffolds with
different mechanical properties are produced depending on the
desired clinical application. For example, scaffolds for cartilage
tissue engineering in the articular joint must survive higher
mechanical stresses than a cartilage tissue engineering system in
other body sites. Thus, hydrogels with mechanical properties that
are easily manipulated may be desired.
[0070] Cytotoxicity of the biopolymer scaffold system may be
evaluated with any suitable cells, such as fibroblasts, by, for
example, using a live-dead fluorescent cell assay and a suitable
indicator of viability, such as a vital stain, such as a
tetrazolium dye, such as MTT, a compound that actively metabolizing
cells convert from yellow to purple.
[0071] Certain GlcN molecules of interest can serve as carriers of
pharmaceutically active agents, biologically active agents and the
like. The carrying function can be non-specific wherein the active
agent non-specifically becomes associated with a GlcN molecule of
interest. Biologically active agents may be incorporated into the
polymer by mere admixture. That can result in encapsulation,
entrapment or engulfment by a GlcN-containing structure, such as
cochleates, vesicles, pouches and the like.
[0072] Alternatively, the agents may be incorporated into a
multi-layer polymer or attached to a polymer of interest by binding
these agents to the functional groups on the polymers. Such
compositions may include linkages that can be easily biodegraded,
for example as a result of enzymatic degradation, resulting in the
release of the active agent into the target tissue, where it will
exert its desired therapeutic effect.
[0073] A simple method for incorporating biologically active agents
containing nucleophilic groups into the polymer involves mixing the
active agent with a polyelectrophilic component prior to addition
of the polynucleophilic component. By varying the relative molar
amounts of the different components of the reactive composition, it
is possible to alter the net charge of the resulting polymer
composition, for example, to prepare a composition for the delivery
of a charged compound, such as a protein or ionizable drug. As
such, the delivery of charged proteins or drugs, which would
normally diffuse rapidly out of a neutral carrier, can be
controlled.
[0074] For example, if a molar excess of a component that is
polynucleophilic is used, the resulting composition may have a net
positive charge and can be used to ionically bind and deliver
negatively charged compounds. Examples of negatively charged
compounds that can be delivered from these matrices include various
drugs, cells, proteins and polysaccharides.
[0075] If a molar excess of a component that is polyelectrophilic
is used, the resulting composition has a net negative charge and
can be used to ionically bind and deliver positively charged
compounds. Examples of positively charged compounds that can be
delivered from these matrices include various drugs, cells,
proteins, and polysaccharides.
[0076] The terms "active agent," "pharmaceutically active agent"
and "biologically active agent" are used interchangeably herein to
refer to a chemical or biological compound that induces a desired
physical, pharmacological or physiological effect, wherein the
effect may be prophylactic or therapeutic. The terms also encompass
pharmaceutically acceptable, pharmacologically active derivatives
of those active agents specifically mentioned herein, including,
but not limited to, salts, esters, amides, prodrugs, active
metabolites, analogs and the like. When the terms "active agent,"
"pharmacologically active agent" and "drug" are used, then, it is
to be understood that the invention includes the active agent per
se as well as pharmaceutically acceptable, pharmacologically active
salts, esters, amides, prodrugs, metabolites, analogs etc. As
described herein, a biologically active agent includes a living
entity, such as a virus, microbe or cell.
[0077] The biologically active agent may vary widely with the
intended purpose for the composition. The term "active" is
art-recognized and refers to any chemical moiety that has a
biological, physiological or pharmacological activity that acts
locally or systemically in a subject. Examples of biologically
active agents, that may be referred to as "drugs", are described in
well-known literature references such as the Merck Index, the
Physicians Desk Reference and The Pharmacological Basis of
Therapeutics, and include, without limitation, medicaments;
vitamins; mineral supplements; substances used for the treatment,
prevention, diagnosis, cure or mitigation of a disease or illness;
substances which affect the structure or function of the body; or
pro-drugs, which become biologically active or more active after
they have been placed in a physiological environment. Various forms
of a biologically active agent may be used which are capable of
being released by the subject composition, for example, into
adjacent tissues or fluids on administration to a subject.
[0078] Further examples of biologically active agents include,
without limitation, enzymes, receptor antagonists or agonists,
hormones, growth factors, autogenous bone marrow, antibiotics,
antimicrobial agents and antibodies. The term "biologically active
agent" is also intended to encompass various cell types and nucleic
acids that can be incorporated into the compositions of the
invention. Thus, a GlcN composition can contain collagen and other
biological molecules. The GlcN composition can contain other
molecules associated with cell tissue and biological adhesion in
general, such as RGD peptides.
[0079] In certain embodiments, the subject compositions comprise
about 1% to about 75% or more by weight of the total composition,
alternatively about 2.5%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70% or
more, of a biologically active agent.
[0080] Non-limiting examples of biologically active agents include
following: adrenergic blocking agents, anabolic agents, androgenic
steroids, antacids, anti-asthmatic agents, anti-allergenic
materials, anti-cholesterolemic and anti-lipid agents,
anti-cholinergics and sympathomimetics, anti-coagulants,
anti-convulsants, anti-diarrheal, anti-emetics, anti-hypertensive
agents, anti-infective agents, anti-inflammatory agents such as
steroids, non-steroidal anti-inflammatory agents, anti-materials,
anti-manic agents, anti-nauseants, anti-neoplastic agents,
anti-obesity agents, anti-parkinsonian agents, anti-pyretic and
analgesic agents, anti-spasmodic agents, anti-thrombotic agents,
anti-uricemic agents, anti-anginal agents, antihistamines,
anti-tussives, appetite suppressants, benzophenanthridine
alkaloids, biologicals, cardioactive agents, cerebral dilators,
coronary dilators, decongestants, diuretics, diagnostic agents,
erythropoietic agents, estrogens, expectorants, gastrointestinal
sedatives, agents, hyperglycemic agents, hypnotics, hypoglycemic
agents, ion exchange resins, laxatives, mineral supplements,
mitotics, mucolytic agents, growth factors, neuromuscular drugs,
nutritional substances, peripheral vasodilators, progestational
agents, prostaglandins, psychic energizers, psychotropics,
sedatives, stimulants, thyroid and anti-thyroid agents,
tranquilizers, uterine relaxants, vitamins, antigenic materials and
pro-drugs.
[0081] Specific examples of useful biologically active agents the
above categories include: (a) anti-neoplastics such as androgen
inhibitors, antimetabolites, cytotoxic agents and immunomodulators;
(b) anti-tussives such as dextromethorphan, hydrobromide,
noscapine, carbetapentane citrate and chlophedianol hydrochloride;
(c) antihistamines such as chlorpheniramine phenindamine tartrate,
pyrilamine doxylamine succinate and phenyltoloxamine citrate; (d)
decongestants such as hydrochloride, phenylpropanolamine
hydrochloride, pseudoephedrine hydrochloride and ephedrine; (e)
various alkaloids such as codeine phosphate, codeine sulfate and
morphine; (f) mineral supplements such as potassium chloride, zinc
chloride, calcium carbonate, magnesium oxide and other alkali metal
and alkaline earth metal salts; (g) ion exchange resins; (h)
antipyretics and analgesics such as acetaminophen, aspirin and
ibuprofen; (i) appetite suppressants such as phenyl-propanolamine.
or caffeine; (j) expectorants such as guaifenesin; (k) antacids
such as aluminum hydroxide and magnesium hydroxide; (l) biologicals
such as peptides, polypeptides, proteins and amino acids, hormones,
interferons, cytokines and other bioactive peptidic compounds, such
as calcitonin, ANF, EPO and insulin; (m) anti-infective agents such
as anti-fungals, anti-virals, antiseptics and antibiotics; and (n)
desensitizing agents and antigenic materials, such as those useful
for vaccine applications.
[0082] Biologically active agents also include living entities,
such as cells. Thus, for example, mesenchymal stem cells can be
attached to or entrapped within a matrix comprising the polymers of
interest. Mesenchymal stem cells may not be differentiated and
therefore may differentiate to form various types of new cells due
to the presence of an active agent, such as GlcN, or the effects
(chemical, physical etc.) of the local tissue environment. Examples
of mesenchymal stem cells include bone marrow cells, osteoblasts,
chondrocytes and fibroblasts. For example, osteoblasts can be
delivered to the site of a bone defect to produce new bone;
chondrocytes can be delivered to the site of a cartilage defect to
produce new cartilage; fibroblasts can be delivered to produce
collagen wherever new connective tissue is needed; neurectodermal
cells can be delivered to form new nerve tissue; epithelial cells
can be delivered to form new epithelial tissues, such as liver,
pancreas etc.
[0083] The cells may be either allogeneic or xenogeneic in origin.
For example, the compositions can be used to deliver cells of other
species that have been genetically modified. In some embodiments,
the compositions of the invention may not easily be degraded in
vivo, cells entrapped within the polymer compositions will be
isolated from the patient cells and, as such, should not provoke an
immune response when returned to the patient.
[0084] To entrap the cells within a polymer, the cells may, for
example be mixed with a composition comprising functionalized
polymer, and optionally, a further biocompatible polymer. That may
occur through a particular reaction or may occur during the making
of a multiple layer polymer. Alternatively, the cells may be
contained within a target entity attached to a polymer of
interest.
[0085] Various forms of the biologically active agents may be used.
These include, without limitation, such forms as uncharged
molecules, molecular complexes, salts, ethers, esters, amides, and
the like, which are biologically activated when implanted, injected
or otherwise placed into a subject.
[0086] The polymer of the invention can also comprise additional
biocompatible monomers or polymers so long as there is no
interference with the desirable characteristics of the invention.
Such additional monomers and polymers may offer even greater
flexibility in designing the precise profile desired for, for
example, targeted drug delivery, tissue engineering, enhanced
administration or the precise rate of biodegradability or
biocompatibility desired. Various forms advantageously can be
produced including gels, foams, films and other three-dimensional
structures. For example, plasticizers and stabilizing agents known
in the art may be incorporated in compositions of the present
invention.
[0087] A composition of this invention may further contain one or
more adjuvant substances, such as fillers, thickening agents or the
like. In other embodiments, materials that serve as adjuvants may
be associated with the composition. Such additional materials may
affect the characteristics of the composition that results. For
example, fillers, such as bovine serum albumin (BSA) or human serum
albumin (HSA), may be associated with the polymer composition. In
certain embodiments, the amount of filler may range from about 0.1
to about 50% or more by weight of the composition, or about
percent. Incorporation of such fillers may affect the sustained
release rate of any encapsulated substance. Other fillers known to
those of skill in the art, such as carbohydrates, sugars, starches,
saccharides, celluloses and polysaccharides, including and sucrose,
may be used in certain embodiments in the present invention.
[0088] Buffers, acids and bases may be incorporated in the
compositions to adjust for pH. Agents to increase the diffusion
distance of agents released from the composition may also be
included.
[0089] The charge, lipophilicity or hydrophilicity of any subject
composition may be modified by employing an additive. For example,
surfactants may be used to enhance miscibility of poorly miscible
liquids. Examples of suitable surfactants include sodium lauryl
sulfate, betaines and other amphoteric compounds. In general,
surfactants are used in low concentrations, generally less than
about 5%.
[0090] The polymer, alternatively, may be formed as a solid object
implantable in the anatomic area, or as a film or mesh that may be
used to cover a segment of the area. Known inert ingredients can be
mixed with a polymer of interest to make a suitable form; such as
film, scaffold, gel and so on, as taught herein. A variety of
techniques for implanting solid objects in relevant anatomic areas
will be likewise familiar to practitioners of ordinary skill in the
art.
[0091] In some embodiments, compositions disclosed herein may be
positioned in a surgically created defect that is to be
reconstructed, and is to be left in this position after the
reconstruction has been carried out. The present invention may be
suitable for use with local tissue reconstructions, pedicle flap
reconstructions or free flap reconstructions.
[0092] The reactive components of the polymer, such as monomers or
oligomers, can be infused or instilled at a desired site. The
present invention may be prepared to include an appropriate vehicle
for this injection, implantation, infusion or direction. Once at
the site, a composition of interest can be polymerized as taught
herein or as known in the art. The polymer then will react with the
surface of interest, such as a tissue. Thus, the polymer is
"biologically anchored" to the host tissue. A suitable polymerizing
initiator can be used, as known in the art.
[0093] All of the reagents necessary to make a composition of
interest are commercially available or can be attained from natural
sources practicing known methods.
[0094] In some embodiments, the invention is directed to kits. In
certain embodiments, this invention contemplates a kit including
subject compositions and instructions for use. For example, the kit
may comprise a GlcN biologically compatible polymer. The kit may
contain suitable instructions.
[0095] A composition of interest can comprise a polymer of interest
or combinations of polymers of interest in a single solution. Thus,
a synthetic synovial fluid can contain, for example, a polyGlcN and
a GlcN-derivatized chondroitin sulfate. The specific amounts of
each polymer can be adjusted at the design of the artisan and again
the final amounts of each of the two polymers are configured such
that the final solution approximates the viscosity of naturally
occurring synovial fluid.
[0096] Once synthesized, the polymers are purified in a matter
compatible with pharmaceutical administration, practicing methods
known in the art. The biological polymers of interest are then
finished in a form suitable for storage and eventual use. Thus, the
biological polymers can be suspended in a biologically compatible
and pharmaceutically acceptable liquid diluent or can be desiccated
or freeze-dried to form a dry powder for later reconstitution and
administration.
[0097] The liquid form is suitable for administration using known
means, such as with a syringe and needle. Suitable amounts of
replacement/supplemental fluid of interest are introduced into the
body site as needed.
[0098] Suitable diluents include sterile water and biocompatible
buffers such as phosphate buffered saline.
[0099] To prolong shelf life and to comply with regulatory
guidelines for use with animals and humans, the reagents and
components for practicing the invention, and for inclusion in a
kit, can be sterilized. Chemical reagents can be exposed to forms
of sterilization suitable to the reagent as known in the art. Thus,
some chemical reagents can be heat sterilized, for example, using
steam, or pasteurized. Other reagents can be sterilized by passage
through filtration media that can remove pathogens, such as a
membrane filter of appropriate pore size. Alternatively, cold
sterilization techniques can be practiced to avoid using heat.
Suitable cold sterilization techniques include use of ethylene
oxide, irradiation, using gamma rays, xrays, electron beams, plasma
or microwaves, ozone and the like. Some of the cold sterilization
techniques may be performed below ambient temperature including
below 0 degrees C. The sterilization can be performed at ambient,
lower or higher pressures. Also, ambient or inert atmosphere can be
used. Additionally, excipients, such as sugars, organic acids, such
as ascorbate or citric acid, and other stabilizers can be added to
the reagents prior to sterilization.
[0100] A synthetic scheme for making a polyGlcN is set forth in
FIG. 1. GlcN at a suitable concentration in a suitable buffer is
mixed with methacrylate anhydride. The result of that reaction is a
derivatized GlcN carrying an acrylic group. That molecule can be
polymerized via the acrylate moiety.
[0101] Another form of polyGlcN is depicted in FIG. 2. Reagent
grade GlcN is mixed with glutamic anhydride. The amine group of
GlcN is derivatized by the anhydride group. That molecule is
reacted in a condensation reaction.
[0102] FIG. 3 depicts a synthetic scheme for derivatizing
chondroitin sulfate (CS) with GlcN. CS is reacted with glycidyl
methacrylate to yield chondroitin sulfate derivatized with a
methacrylate group (CSMA). The methacrylate group can be found at
any of three different reactive oxygen sites, one located at the
carboxyl group, another at the 6' hydroxyl group, and the third on
the sulfate group. The resulting chondroitin sulfate methacrylate
can, for example, be reacted with, for example, the GlcN
methacrylate provided hereinabove to yield chondroitin sulfate
derivatized with GlcN.
[0103] Similarly, hyaluronic acid can be reacted with a
methacrylate, such as glycidyl methacrylate, to yield hyaluronic
acid methacrylate. The hyaluronic acid methacrylate then can be
reacted with, for example, the GlcN methacrylate as described
hereinabove to yield hyaluronic acid derivatized with GlcN.
[0104] A GlcN residue of interest can be derivatized with a number
of different moieties to generate a reactive molecule suitable for
polymerization or functionalization. Thus, GlcN is reacted with
succinic anhydride in the presence of sodium bicarbonate and
methanol to yield an N derivatized molecule (Kadokawa et al., J
Macromol. Rapid Comm 15, 971, 1994). GlcN residues having different
spacer lengths can be made using homologs of succinic anhydride or
compounds related to succinic anhydride that contain structures
that differ from the two carbon fragment found between the carboxyl
functions found in succinic anhydride. The so derivatized GlcN
molecules can be polymerized by reaction with
hexachlorotriphosphazene in pyridine, as known in the art.
[0105] Some GlcNs of interest can be used as a lubricant, shock
absorber or support mechanism. Thus, a GlcN of interest can be used
as a replacement synovial fluid.
[0106] Other GlcNs of interest can be formed into films, such as
available hyaluronic acid films which can be used to provide a
temporary covering for or roof of a hole or void, such as a wound.
The films also can be used as linings or coatings of devices, or
prostheses and objects for implantation. The film can be affixed
onto the device by mere adherence or the two opposing surfaces can
be treated or derivatized with complementary reagents to ensure a
bonding of the film to the surface.
[0107] In other embodiments, a GlcN of interest is configured to
form a scaffold, grid, mesh or any form of a three-dimensional
support, for example, to serve as a substitute-for cell attachment
in tissue engineering applications.
[0108] Such forms generally will be introduced surgically using
known methods.
[0109] All references cited herein are incorporated by reference in
entirety.
[0110] It should be understood that various changes and
modifications to the presently preferred embodiments described
herein will be apparent to those skilled in the art. Such changes
and modifications can be made without departing from the spirit and
scope of the present invention and without diminishing its intended
advantages.
* * * * *