Compositions for use in tissue restructuring and tissue regeneration

Abstract

This disclosure relates to compositions for use as fillers for tissue lumens and cavities in the treatment of pathological conditions requiring tissue reconstruction and regeneration, more particularly in the treatment of fistulas, and comprising a prepolymer component and a pologen.

Description

[Technical Field]

[0001] The present invention relates to compositions for use as fillers for soft tissue lumens and cavities, for example in the treatment of pathological conditions requiring tissue reconstruction and regeneration, and more particularly in the treatment of fistulas, as well as compositions, syringes, and kits suitable for use in these treatments. The present invention further relates to methods for treating pathological conditions requiring tissue reconstruction and regeneration, for example in the treatment of fistulas. [Background technology]

[0002] A fistula is an abnormal passage between two organs or blood vessels that are not normally connected. Perianal fistulas can occur between the anal canal, which includes the colon, part of the intestine, or rectum, and the skin around the anus. Other fistulas are named after the area of ​​the body in which they occur and include enterocutaneous fistulas (between the small intestine and the abdominal skin), rectovaginal fistulas (between the rectum and the vagina), and oromaxillary fistulas (between the mouth and the paranasal sinuses). Perianal fistulas most commonly arise from perianal abscesses or as a result of inflammatory bowel disease (usually Crohn's disease). If left untreated, fistulas can have a significant impact on the patient's quality of life, both physically and psychologically. Perianal fistulas are classified based on their morphology, location, and the percentage of external sphincter affected. Approximately 70% are classified as simple, and 30% as complex. Despite the diverse range of treatment options available for perianal fistulas, none currently offer both a high success rate and low sphincter damage. Sphincter damage can lead to fecal incontinence. Furthermore, depending on the morphology of the fistula and the presence of lesions in the anal tissue, patients may not be candidates for any of the surgical procedures. Fistula incision is a surgical procedure in which a fistula is cut open and can heal as a flat scar. This procedure is suitable only for simple fistulas. For complex fistulas, surgical techniques include extension flap surgery and ligation (LIFT) of intersphincteric fistulas. Device-based treatment for complex fistulas includes the use of bioplugs and fibrin adhesive injection. Surgical procedures typically have a reasonable success rate but carry risks of recurrence, reinfection, and fecal incontinence. Device-based procedures (plugs and adhesives) have a lower risk of fecal incontinence but have other limitations such as discharge of the plug or adhesive, the device failing to properly fill the fistula, or leakage during the procedure due to the poor effectiveness of the adhesive. Therefore, there is still an unaddressed medical need for novel solutions for fistula treatment, more generally for the treatment of pathological conditions requiring tissue reconstruction and regeneration, which could preserve the sphincter muscle, be safe, easy to use, and efficient at the same time. [Overview of the project]

[0003] The present invention provides treatment options for pathological conditions requiring tissue reconstruction and regeneration. More specifically, the present invention provides treatment options for use as fillers for tissue lumens and cavities, for example, for fistulas, which avoid the drawbacks of prior art treatments. More specifically, the present invention provides a patient-helpful composition that reduces or completely eliminates the associated risk of incontinence in the healing and closure of fistulas. More specifically, the composition (i) fits as a filler for tissue lumens and cavities, such as fistula tracts, (ii) is not excreted from the body during healing, i.e., adheres to the tissue after implantation and colonizes by cells, and (iii) hardens within minutes after delivery. After hardening, the composition becomes solid but adheres to the surrounding tissue and becomes a flexible porous filler that allows for rapid intra-tissue growth. Compared to existing products, the composition may improve healing rates while having little or no effect on, for example, excretion control. The composition can be delivered to a target site, such as a fistula, for example, using a syringe. The viscosity of the composition may be such that it can be easily delivered into a fistula, for example, and its adhesiveness may be such that, once polymerization occurs in situ, it is retained in a predetermined position, for example, within the fistula. The prepolymer components in the composition undergo crosslinking while in a predetermined position, such as within the fistula, and as a result, the composition becomes adhesive, which may lead to better retention of the composition, for example, within the fistula.

[0004] The present invention provides a composition for use in pathological situations where tissue reconstruction and tissue reorganization are required, more particularly for use as a filler for soft tissue lumens and voids, and more particularly for use in fistula treatment. The composition comprises a prepolymer component and a porogen; The polymer backbone of the prepolymer component comprises polymer units of the general formula (-A-B-) . (wherein A is derived from a substituted or unsubstituted polyol, B is derived from a substituted or unsubstituted polyacid, and n is greater than 1) The present invention also provides: A composition comprising a prepolymer component and a porogen; the polymer backbone of the prepolymer component comprises polymer units of the general formula (-A-B-) n . (wherein A is derived from a substituted or unsubstituted polyol, B is derived from a substituted or unsubstituted polyacid, n is greater than 1, and on the polymer backbone there is a functional group containing a functional group of formula (I)

Chemical formula

[0005] According to a preferred embodiment, the polymer backbone of the prepolymer component comprises polymer units of the general formula (-A-B-) n , (wherein A is derived from a substituted or unsubstituted polyol, B is derived from a substituted or unsubstituted polyacid, n is greater than 1, and on the polymer backbone there is a functional group containing a functional group of formula (I):

Chemical formula

[0006] In one embodiment, the composition of the present invention further comprises at least one photoinitiator and / or redox initiator system. The present invention also provides a syringe containing the composition according to the present invention. This invention also includes, separately formulated from each other, (i) A first composition comprising a prepolymer component, wherein the polymer backbone of the prepolymer component is of the general formula (-AB-) n A first composition comprising polymer units (wherein A is derived from a substituted or unsubstituted polyol, B is derived from a substituted or unsubstituted polyacid, and n is greater than 1); and (ii) A second composition containing a pologen We also offer parts kits that include this.

[0007] In one embodiment, the polymer backbone of the prepolymer component of the first composition contains a functional group comprising the functional group of formula (I): [ka] (In the formula, R x , R y and R z (This is independently selected from H, alkyl, alkenyl, phenyl, aryl, substituted alkyl, substituted aryl, carboxylic acid, ester, amide, amine, urethane, ether, and carbonyl.) Furthermore, the polymer backbone of the prepolymer component may further contain one or more functional groups, including charged atoms.

[0008] The present invention also relates to a method for treating a fistula, for example, for use as a filler for soft tissue lumens and cavities, for treating pathological conditions requiring soft tissue reconstruction and tissue regeneration, comprising delivering the composition (for example, into the fistula), wherein the composition Contains prepolymer components and pologens; The polymer backbone of the prepolymer component is given by the general formula (-AB-). n Includes polymer units (wherein A is derived from a substituted or unsubstituted polyol, B is derived from a substituted or unsubstituted polyacid, and n is greater than 1) Provide a method. In one embodiment, the polymer backbone of the prepolymer component comprises a functional group of formula (I): [ka] (In the formula, R x , R y and R z (This is independently selected from H, alkyl, alkenyl, phenyl, aryl, substituted alkyl, substituted aryl, carboxylic acid, ester, amide, amine, urethane, ether, and carbonyl.) Furthermore, the polymer backbone of the prepolymer component may further contain one or more functional groups, including charged atoms. While the present invention is described in detail for use in the treatment of fistulas, it is important to note that the present invention can also be used, more specifically as a filler for soft tissue lumens and cavities, in the treatment of any pathological condition requiring soft tissue reconstruction and tissue regeneration. [Modes for carrying out the invention]

[0009] Prepolymer components This composition has the general formula (-AB-). n It contains a prepolymer component having a polymer backbone with polymer units. (wherein A is derived from a substituted or unsubstituted polyol, B is derived from a substituted or unsubstituted polyacid, and n is greater than 1) The term "substitution" has its usual meaning in chemical nomenclature and is used to describe chemical compounds in which a hydrogen atom on the main carbon chain is replaced by a substituent such as alkyl, aryl, carboxylic acid, ester, amide, amine, urethane, ether, or carbonyl. Component A of the polymer backbone is derived from substituted or unsubstituted polyols, such as diols, triols, tetraols, or higher polyols, or mixtures thereof. Suitable polyols include diols such as alkanediols, preferably octanediol; triols such as glycerol, trimethylolpropane, trimethylolpropane ethoxylate, and triethanolamine; tetraols such as erythritol and pentaerythritol; and higher polyols such as sorbitol. Component A may also be derived from other polyols, including unsaturated polyols such as tetradeca-2,12-diene-1,14-diol and polybutadiene-diol, or macromonomer polyols such as polyethylene oxide, polycaprolactone triol, and N-methyldiethanolamine (MDEA). The polyol is preferably substituted or unsubstituted glycerol.

[0010] Component B of the polymer backbone is derived from a polyacid or a mixture thereof, preferably a diacid or triacid. Exemplary acids include, but are not limited to, glutaric acid (5 carbons), adipic acid (6 carbons), pimelic acid (7 carbons), sebacic acid (8 carbons), azelaic acid (9 carbons), and citric acid. Exemplary long-chain diacids include diacids having more than 10, more than 15, more than 20, and more than 25 carbon atoms. Non-aliphatic diacids may also be used. For example, variations of the above diacids having one or more double bonds can be used to produce polyol-diacid copolymers. The polyacid is preferably substituted or unsubstituted sebacic acid.

[0011] In one embodiment of the present invention, the polymer backbone is polyglycerol sebacate. The polyol-based polymers described in U.S. Patents No. 8,912,304, No. 7,722,894, No. 8,143,042, U.S. Patent Application Publication No. 2019 / 0071537, and U.S. Patent Application Publication No. 2022 / 0380531, whose contents are incorporated herein by reference, are suitable prepolymer components for use in the present invention. The molar ratio of polyol to polyacid in the polymer backbone is preferably in the range of about 0.5:1 to about 1.5:1, more preferably in the range of about 0.9:1.1 to about 1.1:0.9, and most preferably about 1:1.

[0012] Alternatively, the polymer backbone of the prepolymer is a polyamide or polyurethane backbone. For example, a polyamine (containing two or more amino groups) may be used to react with a polyacid together with or after reacting with a polyol. An example of poly(esteramide) is described in Cheng et al., Adv. Mater. 2011, 23, 1195-11100, the contents of which are incorporated herein by reference. In other examples, a polyisocyanate (containing two or more isocyanate groups) may be used to react with a polyacid together with or after reacting with a polyol. An example of polyester urethane is described in U.S. Patent Application Publication No. 2013 / 231412. In one embodiment, the prepolymer component in the composition of the present invention contains an activating group on its polymer backbone.

[0013] An activating group is a functional group that can react or be reacted to form crosslinks. The prepolymer provides one or more functional groups that can be activated by reacting one or more functional groups on the monomer units of the backbone, and which can react or be reacted to form crosslinks to yield a cured polymer. Suitable functional groups for activation on the prepolymer backbone include hydroxyl groups, carboxylic acid groups, amines, and combinations thereof, preferably hydroxyl groups and / or carboxylic acid groups. Free hydroxyl groups or carboxylic acid groups on the prepolymer can be activated by functionalizing the hydroxyl group using a moiety that can form crosslinks between polymer chains. The group to be activated may be a free hydroxyl group or carboxylic acid group on moiety A and / or moiety B of the polymer backbone. Free hydroxyl groups or carboxyl groups can be functionalized with a variety of functional groups, such as vinyl groups. Vinyl groups can be introduced by a variety of techniques known in the art, such as vinylization or acrylication. According to the present invention, vinyl groups have the following structure -CR p =CR q R r Includes. (In the formula, R p , R q , R r (These are independently selected from the group consisting of H, alkyl such as methyl or ethyl, alkenyl, aryl such as phenyl, substituted alkyl, substituted aryl, carboxylic acid, ester, amide, amine, urethane, ether, and carbonyl.)

[0014] The activating group is preferably an acrylate group or contains an acrylate group. In this invention, the acrylate group is the following group: -C(=O)-CR x =CR y R z It may include R. (In the formula, R x , R y , R z(Independently selected from H, alkyl such as methyl or ethyl, alkenyl, aryl such as phenyl, substituted alkyl, substituted alkenyl, substituted aryl, carboxylic acid, ester, amide, amine, urethane, ether, and carbonyl) In another embodiment, the acrylate group is the following group: -C(=O)NR m -CR n R u -CR v R w -OC(=O)-CR x =CR y R z It may include R. (In the formula, R m , R n , R u , R v , R w , R x , R y and R z In one embodiment, the activated prepolymer contains a mixture of various acrylate groups (which are independently selected from the group consisting of H, alkyl such as methyl or ethyl, aryl such as phenyl, substituted alkyl, substituted aryl, carboxylic acid, ester, amide, amine, urethane, ether, and carbonyl). In one embodiment, the activated prepolymer contains a methacrylate group. In one embodiment, the prepolymer component in the composition of the present invention has a functional group (activating group) containing the functional group of formula (I) on the polymer backbone.

[0015] [ka] (In the formula, R x , R y and R z (The alkyl, alkenyl, and aryl groups are independently selected from H, alkyl, alkenyl, and aryl.) The alkyl, alkenyl, and aryl groups may be unsubstituted or substituted. -C(=O)-CR x =CR y R z All or part of the acrylate group containing the group is R x , R y and R z Is H; or Rx is CH3, and R y and R z is H; or R x and R y is H, and R z is CH3; or R x and R y is H, and R z is preferably phenyl.

[0016] The prepolymer in the composition of the present invention preferably derives from an activated prepolymer having the general formula (I bis).

Chemical formula

[0017] Preferably, R x , R y , and R z are H; or R x is CH3, and R y and R z are H; or R x and Ry is H and R z is CH3; or R x and R y is H and R z is phenyl. R m , R n , R u , R v and R w is preferably H. Preferably, p is an integer from 1 to 20, more preferably 2 to 10, still more preferably 4 to 10. The case where p = 8 is most preferred. The functional group (activating group) of formula (I) can react or undergo a reaction to form a crosslink.

[0018] In one embodiment of the present invention, the prepolymer component is polyglycerol acrylated sebacate (PGSA). The synthetic route to polyglycerol acrylated sebacate is described in International Publication No. 2016 / 202984. In one embodiment of the present invention, at least a part of the activating groups on the polymer backbone of the prepolymer can be acrylate groups (e.g., acrylate, methacrylate). The degree of activation (e.g., acrylation) is 1 preferably measured by techniques such as 1H NMR. The degree of activation (e.g., acrylation) is preferably characterized as "DA". The ratio of the activating groups can be compared with the number of monomer units in the backbone. This can vary and can be, for example, 0.1 - 0.8 mol / mol of monomer units, preferably 0.2 - 0.6 mol / mol of monomer units, most preferably 0.3 - 0.45 mol / mol of monomer units, such as 0.3 mol / mol of monomer units, etc. When the degree of activation is as described above and the reactive functional group is acrylate, i.e., when the degree of acrylation is as described above, it is most preferred. The polymer units of the backbone are of the general formula (-A-B-) nWhen A is derived from a substituted or unsubstituted polyol and B is derived from a substituted or unsubstituted polyacid, the monomer unit is of the general formula -AB-, and the ratio of activating groups can be expressed per mole of polyacid or per mole of polyol. The DA range shown above is preferably mol / mol of polyacid.

[0019] In one embodiment of the present invention, the functional groups on the polymer backbone include one or more functional groups containing a charged atom. The one or more functional groups containing a charged atom may be selected from the functional groups of formulas (II), (III), (IV), and (V). [ka] (In the formula, R a , R b , R c , R d , R e and R f R is independently selected from H, alkyl, alkenyl, and aryl. The alkyl, alkenyl, and aryl groups are either unsubstituted or substituted. In one embodiment of the present invention, R a , R b , R c , R d , R e and R f (The group is independently selected from H, alkyl, alkenyl, and aryl, and the alkyl, alkenyl, and aryl groups are unsubstituted.)

[0020] Prepolymer components suitable for use in the present invention are disclosed in International Publication Nos. 2021 / 078962 and International Publication Nos. 2022 / 180038. In one embodiment of the present invention, the prepolymer component is acrylic and aminated polyglycerol sebacate (PGSAA) (i.e., an activated and functionalized prepolymer component), for example, a polymer of formula (VI).

[0021] [ka] (In the formula, p is between 1 and 20, n, m and o are integers greater than 1, R a , R b , R c , R d , R e and R f (This is independently selected from H, alkyl, alkenyl, and aryl atoms.)

[0022] Another PGSAA is shown below: [ka]

[0023] The mass-average molecular weight (Mw) of the prepolymer component is measured by gel permeation chromatography with a refractometer and may be about 1,000 to about 1,000,000 daltons, preferably about 2,000 to about 500,000 daltons, more preferably about 2,000 to about 250,000 daltons, and most preferably about 2,000 to about 100,000 daltons. It is advantageous that the mass-average molecular weight may be less than about 10,000 daltons. The mass-average molecular weight may be about 1,000 to about 10,000 daltons, about 2,000 to about 10,000 daltons, about 3,000 to about 10,000 daltons, or about 5,000 to about 10,000 daltons. A mass-average molecular weight of about 4,500 daltons is preferred. The prepolymer component may have polydispersibility, which, as measured by gel permeation chromatography with a refractometer, is less than 20.0, more preferably less than 10.0, more preferably less than 5.0, and even more preferably less than 2.5. A polydispersity of approximately 2.5 is preferred. As used herein, the term “about” means within 10%, preferably within 8%, and more preferably within 5% of a given value or range. In certain embodiments, “about X” means X, where X refers to a value or range.

[0024] Pologen Pologens are components that dissolve and / or degrade in vivo. After the composition is used to treat fistulas (i.e., after prepolymer crosslinking), the pologens dissolve and / or degrade, resulting in a network of linked pores within the polymerized composition. Pologens are distinct from the prepolymer components. In a preferred embodiment, the polymerized composition is soluble and / or decomposed, and the pologen dissolves and / or decomposes faster than the polymerized prepolymer components. In one embodiment of the present invention, the pologen is a hydrogel. The hydrogel is a water-swellable polymer material having a three-dimensional structure. The hydrogel contains both the polymer material and water. When the pologen is a hydrogel, the mass ratio of polymer material to water in the hydrogel is preferably in the range of 1:10 to 1:1, more preferably 1:6 to 1:2, and more preferably 1:4 to 1:3. The polymer material in the hydrogel may be a polypeptide such as collagen, gelatin, albumin, or derivatives thereof. The polymer material may be gelatin. Gelatin can be crosslinked, such as crosslinked gelatin prepared by chemical treatment (e.g., treatment using glutaraldehyde, carbodiimide, or formaldehyde) or by physical treatment (e.g., by UV or thermal process). Gelatin is preferably thermally crosslinked by heat treatment. Gelatin may also be modified gelatin, such as methacrylate gelatin, in which functional groups are grafted onto the gelatin. Gelatin is preferably medical-grade gelatin. Gelatin in powder form may be used to prepare hydrogels for use in the present invention.

[0025] The polymer material could be collagen. The water in the hydrogel may be saline solution, and as a result, the composition contains salt (sodium chloride). The water is preferably physiological saline solution having a salt concentration of about 0.9 mass / vol. In another embodiment of the present invention, the pologen is a sugar such as sucrose or trehalose, or a polysaccharide such as cellulose, alginate, chitosan, or derivatives thereof. Other ingredients In one embodiment, the composition may contain a photoinitiator. Examples of photoinitiators suitable for use with UV light include: 2-dimethoxy-2-phenylacetophenone, 2-hydroxy-1-[4-(hydroxyethoxy)phenyl]-2-methyl-1-propanone (Irgacure 2959), 1-hydroxycyclohexyl-1-phenyl ketone (Irgacure 184), 2-hydroxy-2-methyl-1-phenyl-1-propanone (Darocur 1173), 2-benzyl-2-(dimehylamino)-1-[4-morpholinyl)phenyl]-1-butanone (Irgacure 369), methylbenzoylformate (Darocur MBF), oxyphenyl-acetic acid-2-[2-oxo-2-phenylacetoxy-ethoxy]-ethyl ester (Irgacure This includes, but is not limited to, 754), 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone (Irgacure 907), diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide (Darocur TPO), phosphine oxide, phenylbis(2,4,6-trimethylbenzoyl) (Irgacure 819), and combinations thereof.

[0026] Examples of photoinitiators for use with visible light include, but are not limited to, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, eosin Y disodium salt, N-vinyl-2-pyrrolidone (NVP), triethanolamine, and camphorquinone. In a preferred embodiment, the composition may include a redox system (i.e., a reducing agent and an oxidizing agent). The reducing agent can be selected from 4-N,N-trimethylaniline, N,N-bis(2-hydroxyethyl)-p-toluidine, N,N-dimethylaniline, N,N-diethylaniline, sodium p-toluenesulfonate, and N-methyl-N-(2-hydroxyethyl)-p-toluidine. The oxidizing agent can be selected from ammonium persulfate, potassium persulfate, or benzoyl peroxide. In one embodiment, the redox system is 4-N,N-trimethylaniline and benzoyl peroxide.

[0027] The reducing agent may be present in an amount of 0.1 to 5% by mass, based on the mass of the composition. The oxidizing agent may be present in an amount of 0.1 to 10% by mass, based on the mass of the composition. In one embodiment, an oxygen inhibitor, such as 4-(diphenylphosphino)styrene or triphenylphosphine, is incorporated into the composition along with the redox system. The oxygen inhibitor may be present in an amount of less than 5% by mass, based on the mass of the composition. In one embodiment, a radical scavenger, such as Tempo, Tempol, or 4-methoxyphenol, is incorporated into a composition, such as a composition containing a redox system. The radical scavenger may be present in an amount of 0.005 to 0.5% by mass, based on the mass of the composition. In a preferred embodiment, the radical scavenger is preferably 4-methomethoxyphenol.

[0028] In one embodiment, the composition comprises a photoinitiator and a redox system (i.e., a reducing agent and an oxidizing agent). The compositions according to the present invention may further contain one or more pharmaceutical agents, therapeutic agents, prophylactic agents, and / or diagnostic agents. The agents may be small molecule agents having molecular weights of less than 2000, 1500, 1000, 750, or 500 Da, biomolecules such as peptides, proteins, enzymes, nucleic acids, polysaccharides, growth factors, cell adhesion sequences such as RGD sequences or integrins, extracellular matrix components, or combinations thereof. Exemplary classifications of small molecule agents include, but are not limited to, anti-inflammatory agents, analgesics, antibacterial agents, and combinations thereof. Exemplary growth factors include, but are not limited to, TGF-β, acid fibroblast growth factor, basic fibroblast growth factor, epidermal growth factor, IGF-I and II, vascular endothelial cell-derived growth factors, bone morphogenetic proteins, platelet-derived growth factors, heparin-binding growth factors, hematopoietic growth factors, peptide growth factors, or nucleic acids. Exemplary extracellular matrix components include, but are not limited to, fibronectin, laminin, elastin, and combinations thereof. These pharmaceutical, therapeutic, prophylactic, and / or diagnostic agents may be released at the fistula site once the composition has been delivered and cured. The compositions according to the present invention may further contain colorants. Preferred examples of colorants are those recommended by the FDA for use in medical devices, pharmaceuticals, or cosmetics.

[0029] Characteristics of the composition The prepolymer component may be present in an amount of 20-60% by mass, or 25-50% by mass, or 30-45% by mass, based on the mass of the composition. Pologens may be present in amounts of 2 to 80% by mass, or 10 to 70% by mass, or 30 to 65% by mass, based on the mass of the composition. The amounts of various components are adjusted by those skilled in the art to provide the composition with desirable properties, particularly viscosity. In one embodiment, the viscosity of the composition is such that the composition is a gel at 25°C and, as measured at 25°C, has an elastic modulus G' greater than the viscosity coefficient G''. The viscosity of the composition is preferably such that it can be easily delivered into the fistula (for example, by extruding it through a syringe or cannula commonly used in the art) and retained in the fistula until the prepolymer hardens. By a preferred embodiment: The prepolymer component is PGSAA, present in an amount of 25-50% by mass. Pologens are sugars and are present in amounts of 50-75% by mass. or Pologens are gelatin hydrogels and are present in amounts of 50–75% by mass (which corresponds to 10–16% by mass in dry gelatin).

[0030] Crosslinking of prepolymer components The prepolymer components can undergo polymerization by crosslinking. During polymerization, the prepolymer forms a crosslinked reticular structure that exhibits remarkable adhesive strength even in the presence of blood and other bodily fluids. The cured polymer obtained after curing is preferably sufficiently elastic and resists movement of underlying tissues, such as tissue shrinkage. The adhesive cured polymer may provide a sealing function that prevents leakage of liquids or gases. The adhesive cured polymer is biodegradable and biocompatible and causes minimal inflammatory responses. The amounts of various components in this composition can be adjusted to achieve an acceptable balance between adhesion and porosity (for intra-tissue growth). A larger amount of prepolymer component may result in better adhesion, but it may also result in lower porosity, which may lead to inadequate intra-tissue growth. This composition is applied to a target site, such as a fistula, while the composition has a lower viscosity, before significant crosslinking of the prepolymer components. After crosslinking, the composition becomes solid but not rigid. After crosslinking, the composition becomes adhesive and is securely held in place, such as within a fistula. After crosslinking, the composition is an adhesive and porous filler, biocompatible, biodegradable, and can colonize cells.

[0031] In one embodiment, crosslinking is achieved by irradiation with light (e.g., UV light) in the presence of a photoinitiator that promotes the reaction. Irradiation may occur when the composition is delivered, for example, into a fistula. In one embodiment, the composition may be delivered using a dual-channel applicator having one channel for delivering the composition and another channel in which an optical fiber is positioned to irradiate the composition in situ. In one embodiment, crosslinking is achieved by a redox reaction. A redox system (reducing agent and oxidizing agent) may be introduced into the composition, and as a result, a redox reaction occurs within the composition, leading to crosslinking. Alternatively, if the composition contains both a photoinitiator and a redox system, it is possible to achieve crosslinking by both light and redox. In certain embodiments, the composition can form pores sufficient to allow cell invasion and intra-tissue growth within the scaffold after the curing process, once the pologen dissolves and / or decomposes. The resulting scaffold is a three-dimensional structure of interconnected pores that allows for cell invasion and intra-tissue growth, and ultimately, tissue replacement of the scaffold. In a particular preferred embodiment, the pores have a diameter of 10 to 1000 μm, more specifically 20 to 100 μm.

[0032] Preparation of composition The compositions of the present invention can be prepared by combining a prepolymer component with a pologen. In certain embodiments, the prepolymer component is compounded with a radical scavenger, such as Tempo, Tempol, or 4-methoxyphenol, before being combined with the pologen. In preferred embodiments, the radical scavenger is 4-methoxyphenol. When the pologen is a polypeptide-containing hydrogel, the composition of the present invention is: The process involves mixing water and polypeptide to form a hydrogel; The process involves mixing the prepolymer component with the hydrogel. It can be prepared by [method]. In a preferred embodiment, water is combined with a salt (e.g., NaCl). In a preferred embodiment, this is a saline solution (also known as a saline solution) which is a mixture of sodium chloride (salt) and water (0.9 mass / volume).

[0033] Alternatively, water may be replaced with a solvent used in the medical field, such as DMSO, NMP, or a mixture thereof. This composition is preferably prepared at room temperature (e.g., 25°C). Mixing can be carried out using any suitable method, such as using a mixing syringe. When the pologen is a sugar, the composition of the present invention: It can be prepared by a process of mixing sugar and prepolymer components. In one embodiment, pologen (including hydrogelpologen) is combined with a photoinitiator, reducing agent, or oxidizing agent before mixing with the prepolymer components. In another embodiment, when pologen (including hydrogelpologen) is combined with a reducing agent or oxidizing agent before the mixing step, the prepolymer components are combined with the oxidizing agent or reducing agent, respectively (the oxidation-reduction process begins when the reducing agent and oxidizing agent are mixed). The composition of the present invention is preferably prepared immediately before use. This ensures that the composition possesses the necessary properties when delivered, for example, into a fistula.

[0034] In one non-limiting embodiment of the present invention, where the pologen is a hydrogel and crosslinking is achieved by a redox reaction, the composition is as follows: The process of providing polypeptides; The process involves adding water, preferably saline solution, to the polypeptide and mixing the polypeptide with the water to form a hydrogel; The process involves adding a prepolymer component to a hydrogel, mixing the prepolymer component and the hydrogel to form a hydrogel / prepolymer mixture; A step of dividing the hydrogel / prepolymer mixture into a first part and a second part; The first step involves mixing the first part with an oxidizing agent to form an oxidizing mixture; The second step involves mixing the second part with a reducing agent to form a reducing mixture; The process of combining an oxidation mixture and a reduction mixture It can be prepared by a method having [a certain characteristic].

[0035] Treatment of tissue indications The compositions of the present invention are used in indications requiring tissue reconstruction and regeneration. "Tissue" is intended to mean both hard tissue (such as bone or cartilage) and soft tissue. More specifically, the compositions of the present invention are used in procedures for partial or complete occlusion, reinforcement, or filling of tissue lumens and cavities. Lumens are considered to be the cavities of tubular structures such as vascular structures, reproductive tracts, and digestive tracts. Cavities are considered to include lesions, scars, fissures, fistulas, and diverticula. These cavities may be physiological or the result of infection, surgery, cyst removal, tumor removal, trauma, or soft tissue regeneration. Specific examples include wound healing, dental treatment, breast reconstruction, hernia prevention, and osteoporosis. The present invention is described below in relation to its use in the treatment of fistulas, but it is important to note that the compositions of the present invention may also be used in the treatment of any pathological condition requiring tissue reconstruction and regeneration.

[0036] Treatment example: Treatment of fistula The compositions of the present invention can be used for the treatment of fistulas. In one embodiment of the present invention, the fistula is a perianal fistula. Alternatively, the fistula may be an enterocutaneous fistula, a rectovaginal fistula, or an oral-maxillary sinus fistula. The perianal fistula may be a simple fistula or a complex fistula. The composition is delivered into the fistula. In one embodiment of the present invention, the composition is delivered into the fistula using a syringe. Preferably, the amount of composition delivered is sufficient to fill the fistula. The crosslinking reaction may begin immediately after the composition is delivered into the fistula or while the composition is inside the fistula. During polymerization, the composition becomes adhesive and consequently adheres to the fistula wall. Crosslinking preferably begins between immediately after the composition is delivered into the fistula and 5 minutes later. Preferably, crosslinking is completed within 30 seconds to 30 minutes after the composition is delivered into the fistula, resulting in the composition becoming rapidly adhesive and retained within the fistula. This composition conforms to the fistula tract and is not excreted from the body during healing. It adheres to the fistula tissue. When the pologens of this composition decompose or dissolve, they create pores throughout the hardened composition that can be colonized by cells, enabling fistula healing. The prepolymer components are preferably biodegradable so that they decompose slowly within the fistula. PGSA and PGSAA are biodegradable.

[0037] Syringes and kits In one embodiment, a syringe-based device is used to deliver the composition into soft tissue lumens and / or cavities, for example, into fistulas. The syringe may contain the composition. Alternatively, the syringe may contain one or more components of the composition, and other components may be added to the syringe before use. For example, the syringe may contain a pologen (which may contain a photoinitiator, reducing agent, or oxidizing agent), and then the prepolymer component (which may contain a photoinitiator, reducing agent, or oxidizing agent) may be added to the syringe before use. When a redox system is used, it is preferable that the reducing agent and oxidizing agent remain separate until the final mixing before use. Suitable syringes may include double-barrel syringes and syringes equipped with a mixing rod. Mixing of components can be performed within the syringe, for example, using the mixing rod. This invention also includes, separately formulated from each other, (i) A first composition comprising a prepolymer component; and (ii) a second composition comprising a pologen We provide a parts kit that includes this. Before use, the first composition and the second composition may be mixed. In one embodiment, the syringe has a first compartment and a second compartment, the first compartment containing a first composition comprising a prepolymer component, and the second compartment containing a second composition comprising a pologen.

[0038] In another embodiment, the parts kit comprises a first syringe containing a prepolymer component and a second syringe containing a pologen, the first and second syringes connected by a mixing device (e.g., a mixing rod or a stationary mixer). A suitable device is described in U.S. Patent No. 9,662,676. Before use, the first composition and the second composition can be mixed in a syringe, for example, using a mixing rod. In one embodiment, the first composition and the second composition can be mixed in a third compartment. In certain embodiments, the first or second composition further comprises at least one photoinitiator and / or one agent of an oxidation-reduction system. The parts kit may also include instructions for use, for example, for treating fistulas with the composition. The present invention is described herein with reference to examples, which are not intended to limit the invention but are provided as guidelines on how the compositions of the present invention may be used to occlude, enhance, or fill soft tissue lumens and cavities. [Examples]

[0039] The inventors have tested various compositions according to the present invention that can be used in tissue reconstruction and tissue regeneration processes, and more specifically, can be used as space fillers in the treatment of fistulas, for example. More specifically, the inventors evaluated several parameters: ·Adhesion properties • Usefulness (e.g., extrusion through a syringe / cannula) • Porosity and interconnection of pores • In vivo tissue growth in fillers (subcutaneous transplantation in rats)

[0040] Preparation of composition The components used in this composition are summarized in Table 1 below: [Table 1]

[0041] This composition was prepared immediately before use by a method well known in the art. More specifically, the composition for photocuring was prepared as follows: Pologen was weighed in a mixing syringe equipped with a mixing rod (e.g., P-system syringe, Medmix). Saline solution was transferred using a micropipette and mixed with the pologen using the mixing rod of the syringe. The prepolymer component and hydrated pologen were mixed in the same mixing syringe. Compositions 2, 4, 6, 8, 9, 10, 13, 15, and 17 for redox curing were prepared as follows: The prepolymer components were weighed in a Petri dish. The reducing solution, and phosphine if present, were added to the prepolymer using a micropipette. The mixture was homogenized using a spatula and transferred to syringe 1.

[0042] Pologen was weighed in a mixing syringe (syringe 2) (e.g., P-system syringe, Medmix). - Regarding compositions using only BPO Type A (powder): The oxidizing agent powder was transferred to the porogen in syringe 2. Saline solution was transferred to syringe 2 using a micropipette and homogenized using a mixing rod. Syringe 1, containing the prepolymer / reducing solution / phosphine, was transferred to syringe 2. All compounds were homogenized using a mixing rod. - For compositions using only BPO type B (solution): Saline solution was transferred to syringe 2 using a micropipette and homogenized using a mixing rod. Syringe 1, containing the prepolymer / reducing solution / phosphine, was transferred to syringe 2. The compounds were homogenized using a mixing rod. The oxidizing agent solution was added to syringe 2, and all compounds were homogenized using a mixing rod. Compositions 11 and 12 for redox curing were prepared as follows: The prepolymer was weighed in syringe 1. The pologen was weighed in a mixing syringe (syringe 2) (e.g., P-system syringe, Medmix). The oxidizing agent powder was transferred to the pologen in syringe 2. Saline solution was transferred to syringe 2 using a micropipette and homogenized using a mixing rod. Syringe 1, containing the prepolymer, was transferred to syringe 2. All compounds were homogenized using a mixing rod.

[0043] The reducing solution was added to syringe 2 using a micropipette, and the mixture was homogenized using a mixing rod. Composition 14 for redox curing was prepared as follows: The prepolymer was weighed equally into two syringes (syringe 1A and 1B). The pologen was weighed equally into two mixing syringes (syringe 2A and 2B) (e.g., P-system syringe, Medmix). The oxidizing agent powder was transferred to pologen syringe 2A. The saline solution was transferred equally into syringes 2A and 2B and homogenized using a mixing rod. Syringes 1A and 1B containing the prepolymer were transferred to syringes 2A and 2B, respectively. All compounds were homogenized using a mixing rod. The reducing solution was added to syringe 2B and the mixture was homogenized using a mixing rod. Syringe 2A was transferred to one end of a double-barrel syringe (10 mL double-barrel syringe, Medmix), and syringe 2B was transferred to the other end. All components were mixed through a stationary mixer tip (stationary mixer, Medmix) at the time of injection.

[0044] The composition of this composition is shown in Table 2 below: [Table 2-1] [Table 2-2] [Table 2-3]

[0045] Curing process The "photocurable" composition was prepared by combining a prepolymer (PGSA or PGSAA) with a desired amount of TPO, a photoinitiator that promotes polymerization when the composition is irradiated with light. After immediate mixing of the prepolymer compound, pologen, and saline solution (see above), the test composition was exposed to 405 nm light for curing. "Redox" compositions 2, 4, 6, 8, 9, 10, 13, 15, and 17 were prepared by weighing a desired amount of prepolymer into a dish, mixing it with the reducing solution and, if present, phosphine, and then transferring the mixture to syringe 1. - Regarding Type A BPO: The oxidizing agent powder (Type A BPO), pologen, and saline solution were mixed in syringe 2, and then mixed with the contents of syringe 1 to homogenize the composition and initiate curing. - For type B BPO, saline solution and pologen were mixed in syringe 2, then mixed with the contents of syringe 1, and finally mixed with an oxidizing agent solution (type B BPO). This composition was homogenized to initiate curing.

[0046] Redox compositions 11 and 12 were prepared by weighing a desired amount of prepolymer in a syringe (syringe 1). Next, the pologen, oxidizing agent powder (type A BPO), and saline solution were mixed in syringe 2, and then the prepolymer was added by transferring the mixture from syringe 1 to syringe 2. Finally, the reducing solution was added to syringe 2 to homogenize the mixture and initiate curing. The redox composition 14 was prepared by equally weighing the prepolymer into two syringes (syringe 1A and 1B). Next, the pologen, oxidizing agent powder (type A BPO), and saline solution were equally mixed in syringes 2A and 2B, and then the prepolymer was added to syringes 1A and 1B, respectively. The reducing solution was added to syringe 2B. Syringe 2A was transferred to one side of a double syringe, and syringe 2B was transferred to the other side. All components were mixed during injection through a stationary mixer tip to initiate curing.

[0047] Adhesion test The adhesion of the cured composition to muscle tissue was tested using a lap shear protocol comprising the following steps: • Pig muscle tissue was cut to obtain rectangular samples. The product under test was placed on one end of a muscle sample, as close to the boundary as possible. Then, another muscle sample was placed on top. Once curing was achieved, the assembly was placed vertically on the grip of a single-spindle mechanical testing machine. The displacement and load were set to zero, and then the upper grip was raised at a speed of 5 mm / min until the two muscle samples separated. The load-displacement curve was recorded, and the maximum load (in N) before separation was recorded. At the end of the test, the area of ​​the product was measured using a caliper. Next, the maximum load (at N) is calculated based on the area of ​​the polymer in the overlapping region (cm²). 2 This was divided by ). This is the apparent shear strength (N / cm²). 2 )

[0048] The results of the adhesion test, including the number of times the test was repeated, are shown in Table 3: [Table 3] These results demonstrate that the compositions according to the present invention are adhesive. The highest adhesive strength corresponds to pure PGSAA (composition 21), followed by compositions 12, 13, 14, and 15 having the highest PGSAA content (37.00 to 47.51% by mass).

[0049] usefulness The utility of the composition before curing was tested by evaluating its ability to be injected using syringes and catheters. The composition was prepared in a mixing syringe as described in the section on composition preparation, injected with or without a catheter (14G - inner diameter 1.7 mm), and the possibility and ease of injection were qualitatively evaluated using materials suitable for space-filling procedures, such as fistula treatment procedures.

[0050] [Table 4] The injectability of the composition containing gelatin as a pologen was superior to that of composition 18 containing sucrose. Composition 18 is a thicker paste, making it ideal for direct application to the tissue under test, without the need for a catheter.

[0051] porosity The porosity of the composition was evaluated by microcomputed tomography (micro-CT) after forcibly dissolving or degrading the pologen particles in vitro. The analyzed porosity represents the best porosity when all pologen particles are actually dissolved in vivo. The composition was prepared as described in the section on composition preparation and transferred to a cylindrical silicone mold (height = 4 mm, diameter = 5 mm) using a spatula. The sample was exposed to approximately 130 mW / cm² using a TISSIUM Light. 2It was cured using 405nm light in two 30-second cycles. Regarding composition 18: Before freeze-drying at -80°C for 24 hours, the cured disc-shaped sample was immersed in deionized water in a 20 mL vial placed on a roller agitator for 24 hours to elute the spherical sucrose.

[0052] For compositions 6, 11, 12, and 14: The cured disc-shaped samples were immersed for 24 hours in a 20 mL vial of deionized water placed on a roller agitator, incubated for 24 hours three times in a 37°C trypsin bath to decompose the gelatin, rinsed, and freeze-dried at -80°C for 24 hours. After hardening and pologen removal, the disc-shaped samples were sent to Scanco Medical (Switzerland) for micro-CT scanning (μCT 50 scanner). Scanco's proprietary evaluation software was used for segmentation and 3D morphometric analysis. The evaluation method is described by Hildebrand and Ruegsegger (Hildebrand, T. & Ruegsegger, PA new method for the model-independent assessment of thickness in three-dimensional images. J Microsc 185, 67-75 (1997)).

[0053] [Table 5] As shown in Table 5 above, porosity was measured between 46.4% and 67.5% of the total volume of the disc-shaped samples. The linkage density, which estimates the number of interconnected pores per unit volume, was higher for type 2 gelatin (crosslinked) than for type 3 gelatin (uncrosslinked). This indicates that when type 2 gelatin is degraded in vivo, it provides a pathway for cells to reach the center of the porous graft more easily.

[0054] In vivo testing The composition was tested by subcutaneous transplantation in rats and by treatment of perianal fistulas in pigs. (i) Subcutaneous transplantation in rats The purpose of this study was to understand the intratissue growth characteristics by transplanting cured samples of the composition according to the present invention into subcutaneous pockets on the backs of rats. The sample was either disc-shaped or cylindrical. Disc-shaped samples: On the day of transplantation, the composition was prepared as described in the section on composition preparation and transferred to a cylindrical silicone mold (height = 2 mm, diameter = 5 mm) using a spatula. For the photocurable composition, 405 nm light was applied at approximately 130 mW / cm². 2 The top surface of the mold was irradiated for two 30-second cycles. Next, the disc-shaped sample was removed from the mold, and the other side of the disc-shaped sample was irradiated for another 30 seconds. For the redox-curable composition, the composition was allowed to cure for 10 minutes before removing the cured disc from the mold. To reduce the risk of infection after transplantation, the disc-shaped sample was sterilized by ultraviolet sterilization irradiation in a sterile Eppendorf tube before insertion into the dorsal subcutaneous pocket of the rat.

[0055] Cylindrical specimens: In the operating room, the composition was prepared as described in the section on composition preparation and extruded from a syringe onto a sterile dish using a 4 mm diameter catheter. Only the redox-cured composition of the cylindrical specimens was tested. The composition was cured at room temperature for 10 minutes before sectioning with a scalpel. The resulting cylindrical specimens (diameter = 4 mm, length = 1 cm) were inserted into the dorsal subcutaneous pocket of rats. One or three months after transplantation, skin containing individual transplanted specimens (either disc-shaped or cylindrical) was collected for histological examination. Intratissue growth was confirmed by analyzing histological images (cross-sections of the center of the specimen, after hematoxylin and eosin staining) to assess the presence of cells within the pores of the composition, newly formed tissue, and angiogenesis. The depth of invasion of new tissue, starting at the outer edge of the specimen and progressing towards the center, was measured. The results are shown in Table 6:

[0056] [Table 6]

[0057] Introducing pologens into PGSAA enabled in vivo tissue growth: all compositions implanted subcutaneously in rats, with the exception of pure PGSAA, were infiltrated by newly formed tissue. For some compositions, tissue growth in this model was limited to the outer portion of the disc-shaped sample, and cells did not reach the center of a 2 mm thick disc-shaped sample over a 1-month or 3-month in vivo period. Tissue growth across all or half the thickness of the implant was observed in compositions 6, 10, 13, 17, 18, 19, and 20. These compositions were prepared from type 1 gelatin, type 2 gelatin, type 3 gelatin, sucrose, and collagen as pologens, and prepolymer content ranging from 22.52% to 39.16%.

[0058] (ii) Perianal fistula in pigs The porcine model is based on the study by Buchanan et al. (Buchanan, GN et al. Experimental model of fistula-in-ano. Dis Colon Rectum 48, 353-358 (2005)). For the porcine study, fistulas were mechanically created in nine animals using a catheter, dilator, and drain. The drain was left in place for three weeks, and hollow fistula tracts (four per animal) were formed. Each tract was cleaned using a curette to remove granulation tissue and rinsed with saline. The internal opening was closed in an X-shape with two Vicryl 2-0 sutures. The composition of the present invention was injected retrogradely from the internal (closed) opening to the external opening, filling the entire tract.

[0059] The research animals were slaughtered one month after treatment (6 animals) or three months after treatment (3 animals). Compositions 10, 11, 13, and 14 were successfully injected and cured in all fistulas (one per fistula tract). At both time points, all skin and internal openings were closed, demonstrating that the pig model achieved rapid healing regardless of the treatment group. For all four compositions, (a) it was observed that the cured composition was not discharged from the fistula at 1 month (n=16) or 3 months (n=10), and (b) intratissue growth (vascularized fibrous tissue) invading the polymer gaps was observed in the pig "1 month" group and similarly in the "3 months" group. In this pig model of perianal fistula, which closely resembles a clinical scenario for treating gaps in soft tissue, intratissue growth with the cured composition was greater than the intratissue growth observed in subcutaneous pockets in rats at 1 month. Minimal to mild mononuclear inflammatory cells and minimal to mild multinuclear foreign body giant cells were observed at the boundary between the composition and fibrous tissue and in the gaps of the transplanted material. Mononuclear inflammation was similar across all groups, including empty controls (corresponding to the sutured inner opening).

[0060] The inventors have identified compositions of particular interest for indications involving cavity filling in soft tissues, such as fistula treatment. Preferred embodiments have shown that compositions comprising PGSAA and cross-linked gelatin (e.g., thermally cross-linked gelatin) are of particular interest as cavity fillers due to their different properties: (1) adhesion to biological tissues (e.g., muscle), (2) extrusion by syringe through a narrow cannula, (3) having interconnected pores that allow for cell invasion in vivo, and (4) resistance to extrusion even under mechanical constraints in vivo.

Claims

1. A composition for use in tissue remodeling, comprising a prepolymer component and a pologen; The polymer backbone of the prepolymer component is given by the general formula (-A-B-) n A composition containing polymer units. (In the formula, A is derived from a substituted or unsubstituted polyol, B is derived from a substituted or unsubstituted polyacid, n is greater than 1, and the prepolymer component contains an activated functional group on its polymer backbone.)

2. The composition for use according to claim 1, wherein the activated functional group on the polymer skeleton is a functional group of formula (I). 【Chemistry 1】 (In the formula, R x , R y and R z (This is independently selected from H, alkyl, alkenyl, and aryl.)

3. The composition for use according to claim 1 or 2, wherein tissue reconstruction is a treatment of a fistula, including perianal fistulas.

4. A composition for use according to any one of claims 1 to 3, wherein tissue restructuring is treated by delivering the composition from a syringe.

5. A composition comprising a prepolymer component and a pologen; The polymer backbone of the prepolymer component is given by the general formula (-A-B-) n A composition containing polymer units. (In the formula, A is derived from a substituted or unsubstituted polyol, B is derived from a substituted or unsubstituted polyacid, n is greater than 1, and the polymer backbone contains functional groups including the functional group of formula (I)) 【Chemistry 2】 (In the formula, R x , R y and R z (The element is independently selected from H, alkyl, alkenyl, and aryl.)

6. The composition for use according to claim 2, or the composition according to claim 5, wherein the functional groups on the polymer skeleton further comprise one or more functional groups containing charged atoms.

7. A composition for use according to any one of claims 1 to 4 or 6, or a composition according to claim 5 or 6, wherein the pologen is preferably a hydrogel containing a polypeptide.

8. The composition for use according to claim 7, wherein the polypeptide is gelatin, or the composition according to claim 7.

9. A composition for use according to any one of claims 1 to 4 or 7 to 8, wherein the polyol is a triol, preferably glycerol or trimethylolpropaneethoxylate, and the polyacid is a diacid selected from the group consisting of glutaric acid, adipic acid, pimelic acid, sebacic acid and azelaic acid, preferably sebacic acid.

10. A composition for use according to claim 9, or a composition according to claim 9, wherein the prepolymer component is selected from the group consisting of acrylic polyglycerol sebacate (PGSA) and acrylic and aminated polyglycerol sebacate (PGSAA).

11. A composition for use according to any one of claims 1 to 4 or 7 to 10, comprising a photoinitiator, or a composition according to any one of claims 5 to 10.

12. A composition for use according to any one of claims 1 to 4 or 7 to 10, comprising a redox system, or a composition according to any one of claims 5 to 10.

13. A syringe comprising the composition according to any one of claims 5 to 12.

14. Each is formulated separately, (i)A first composition containing a prepolymer component, wherein the polymer backbone of the prepolymer component contains polymer units of the general formula (-A-B-) n The first composition (wherein A is derived from a substituted or unsubstituted polyol, B is derived from a substituted or unsubstituted polyacid, and n is greater than 1); and (ii) A second composition containing pologens A parts kit that includes this.

15. A method for treating a fistula, comprising delivering a composition into the fistula, wherein the composition is Contains prepolymer components and pologens; The polymer backbone of the prepolymer component is given by the general formula (-A-B-) n Includes polymer units (wherein A is derived from a substituted or unsubstituted polyol, B is derived from a substituted or unsubstituted polyacid, and n is greater than 1), method.

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