WO2007017712A1

WO2007017712A1 - Composition comprising polymeric, water-insoluble, anionic particles, processes and uses

Info

Publication number: WO2007017712A1
Application number: PCT/IB2005/003470
Authority: WO
Inventors: Osvaldo Nicolas Griguol; Dante Miguel Beltramo; Ismael Dario Bianco; Roxana Alasino
Original assignee: Promedon Do Brasil Produtos Medico-Hospitalares Ltda.
Priority date: 2005-08-11
Filing date: 2005-08-11
Publication date: 2007-02-15
Also published as: US9017709B2; EP1912627B1; US20090186061A1; EP1912627A1

Abstract

The present invention relates to an injectable composition which comprises polymeric, water-insoluble, non-biodegradable, anionic particles, these particles having an irregular shape and a biocompatible carrier with a lubricated surface, a method for preparing the same, a method for treating a tissue in a patient which comprises injecting into the tissue site the injectable composition as a permanent implant and the use of the injectable composition as a medicament particularly for bulking a tissue site.

Description

COMPOSITION COMPRISING POLYMERIC, WATER-INSOLUBLE, ANIONIC PARTICLES, PROCESSES AND USES

The present invention relates to the permanent augmentation of soft tissues and, more particularly to the treatment of urological disorders, e.g., urinay incontinence, and vesico-ureteral reflux, by endoscopic injection of biocompatible anionic microparticles into submucosal tissues.

Since this invention is closely related to the treatment of incontinence, it will be described in detail by reference thereto.

For a simple explanation, incontinence occurs when the resistance to urine flow has decrease excessively, i.e., urethral resistence to urine outflow has, from whatever cause, been lowered to the point when it can no longer resist to increased intra- abdominal pressure.

The urinary incontinence is a usual problem that affect people of different ages. This pathology predisposes a patient to urinary tract infections and urosepsis among others. The urinary incontinence is also associated with socially and psychology problems, people affected with urinary incontinence show depression and social stigmatization.

One of the treatments actually proposed to solve the urinary incontinence, is the injection of biocompatible polymeric materials in the internal tissue e.g., in the urethra, in order to augment the soft tissue and restore the continence. Many of the biocompatible materials have been used for augmenting the soft tissues e.g. are collagen, gelatin, and specially one of the most biocompatible molecule : hyaluronic acid. Beads of these natural crosslinked polymers are also currently used. However all of those polymers were also biodegradable. More recently, the biomaterials used in the treatment of urinary incontinence are synthetic non-biodegradable polymers and hydrogel polymers such as silicone rubber, polytetrafluoroethylene, polyacrylonitrile-polyacrylamide, and polyacrilates. Moreover, those hydrogel polymers were loaded with biological biodegradable polymers or autologous cells.

Most often, the biomaterials and its biocompatible carrier are delivery to the tissue by injection with an appropriated syringe. The use of various injectable polymeric materials for urinary incontinence through the augmentation of tissues is known in the art.

Related to the use of biocompatible, biodegradable polymers for tissue augmentation, U.S. Pat. N⁰ 5,143,724 describes the use of viscoelastic polymers with high biocompatibility like hyaluronic acid or crosslinked hyaluronans. Those highly anionic materials show very low cell interaction, they are often used in cosmetic surgery, but they have limited use in tissue augmentation due to the fact that hyaluronic acid will spread out of the tissues and also because hyaluronic acid is degraded. Another biocompatible biodegradable biopolymer used in the treatment of urinay incontinence is collagen protein. U.S. Pat. N⁰ 4,837,285 of Berg et al., relates to a collagen-based composition for augmenting soft tissue. The authors describe the use of resorbable matrix beads of collagen with an average pore size of about 50 to 350 μm. Berman C. J. at al., Journal of Urology. 1997, 157;122~124), describe the use of crosslinked collagen in the treatment of urinay incontinence following radical prostatectomy. However the use of collagen shows contradictory results. An study of McCeIl. M, and Delustro, F., published in 1996 in Journal of Urology 155, 2068-2973 suggests the possible sensitization in patients because specific IgG and

IgA antibodies appear after injection of bovine collagen.

Non-biodegradable polymers were used, e.g., injection of polytetrafluoroethylene

(PTFE) in the form of past was used to treat the urinary incontinence, see Kaufman et al, "Transurethral polytetrafluoroethylene injection for post-prostatectomy

Urinary incontinence" 1984 - Journal of Urology .132, p 463-464.

However, the presence of very small PTFE particles in the formulations was a problem since undesirable particle migration and serious granulomatous reaction take place. One commercial product containing PTFE particles with a diameter lower than 30 μm suspended in glycerin is available under name Polytef ®

(trademark of Mentor Corp. of California).

In order to overcome the problem of the migration, it has been proposed to use polymer particles of larger size.

In U.S. Pat. N⁰ 5,336,263 the use of microparticles of silicone (polysiloxane and dimethylsiloxanes), with an average in the particle size in the range of from about

100 to 600 μm, is described as a method for long-term treatment urinary incontinence.

Patent applications EP 636014, U.S. Pat N° 5,258,028 and U.S. Pat N⁰ 5,336,263 describe the use of textured microparticles of silicone in the manufacture of a composition for the long term treatment of urological disorders, such as incontinence. The aforementioned microparticles are dispersed in a physiologically biocompatible carrier and have an average size between 80 and 600 μm. The composition can be injected through a hypodermic needle.

Patent number FR2 836 921 Al also describes a tissue bulking made of silicone. The authors describe injectable foam particles with biocompatible characteristics that are suspended in a biocompatible carrier, in which most of said particles have a diameter comprised between 100 and 2000 μm. This silicone foam particles used for the urinary incontinence have a reversible compression capacity comprised between 300 and 420 %.

The other compositions mentioned in the treatment of urinary incontinence are that mentioned as non-biodegradable water insoluble polymers denominated hydrogel. The EP 402,031 relates to an injectable composition, comprising a plurality of polymeric discrete particles, physiologically compatible, non-biodegradable of an average diameter ranging between 0,27 and 5,08 mm, and having a lubricated surface. These microparticles are deformable in a reversible manner, in approximately 20 to 75% of their external diameter. This composition contains microparticles of polyacrylonitrile in regular shape : in the form of spheres or macrodisc.

U.S. Pat N⁰ 6,335,028 "Implantable particles for urinay incontinence" describes an injectable composition for the treatment of urinary incontinence, gastroesophageal reflux disease and amelioration of skin wrinkles, using a biocompatible hydrophilic cationic copolymer composed by acrylic monomer and cationic monomer. The spherical particles can be loaded with different therapeutics agents such as antidiuretic, antiinflammatories, cell adhesion promoter etc. and also with autologous cells. The spherical microparticles have a diameter ranging between 10 to 1000 microns.

U.S. Patent Application 2002/0068089 describes a method for treating gastroesophageal reflux disease by injection of a bulking agent. This composition also contains cationic biocompatible hydrophilic microparticles that can be loaded with different therapeuthic agents, including autologous cells. Those cationic particles have a diameter ranging between 10 to 1000 microns. . .

WO 0170289 "Injectable and swellable microspheres for tissue bulking" relates to injectable compositions comprising substantially spherical microspheres used for tissue bulking in the treatments of urinary incontinence, urinary reflux disease and gastro-esophageal reflux disease. The microspheres are hydrophilic, biocompatible, swellable polymers like acrylic polymers, starch-acrylonitrile polymers and also polyethylene oxide among others. This composition comprising microspheres also comprises an amount of 10 to 90% of biocompatible saline carrier that contain acylamino-e-propion-amido-3-triiodo-2,4,6-benzoic acid (a contrast agent) and the microspheres have the property to swell about 1 to 4 times their average diameter after injection in the tissues. The microspheres may be also chemically modified with different biological molecules with therapeutic properties. These microspheres may be associated to autologous cells

From this state of the art, it appears that in the recent years many approaches and treatments have been proposed to cure or relieve urinary incontinence by injection. While some of these approaches have enjoyed a relative success, relief has been, for the most part, only temporary in those patients where success is noted. Thus, there remains a very important need for a treatment that will provide a lasting remedy for successfully treatment of such urological disorders.

The problem aimed in the present application is to provide a long lasting, safe, effective treatment of tissue bulking. This problem has been solved by using an injectable composition comprising a discrete population of highly anionic, polymeric particles, having an irregular shape and a biocompatible carrier with a lubricated surface.

Advantageously, this composition allows the improvement of the treatments of urological disorders such as urinary incontinence and urinary reflux disease. ^{' •}

A first object of the present invention is an injectable composition comprising polymeric, water-insoluble, non-biodegradable, anionic particles, these particles having an irregular shape and a biocompatible carrier with a lubricated surface wherein said composition is injectable through needles of about 16 to 30 gauges.

A second object of the present invention is a method for preparing the injectable composition by mixing polymeric, water-insoluble, water swellable , nonbiodegradable, anionic particles of irregular shape and a biocompatible carrier with a lubricated surface.

A third object of the present invention is a method for treating a tissue in a patient, this method comprises injecting into the tissue site the injectable composition according to the invention, particularly this method consists in bulking the tissue site.

Other objects, advantages, features of the present patent application are explained in the following description and examples.

The polymeric particles used in the composition of the present application are water-insoluble that means they can not dissolve in water. These particles are not swellable in conventional conditions. These polymeric particles are non-biodegradable that means they are not absorbed by the body, but these particles are biocompatible.

The injectable composition of particles is subjected to different and exhaustive treatments with different organic solvents and aqueous solvents that include high alkaline pH (pH 12) and high ionic strength (3M NaCl) to remove all the hydrophobic and hydrophilic impurities in order to obtain a injectable composition with physiologically-biocompatible properties.

To be considered as an injectable physiologically-biocompatible composition, the composition must be subjected to a serie of tests that must be approved successfully. The composition of this invention was considered physiologically- biocompatible after approval of the following tests : a- The test of genotoxicity by reverse mutation, developed in Salmonella

Thyphimurium, known as the AMES test, made under ISO 10993-3 norms. b- The cytotoxicity test, according ISO 10993-5. c- The test for bacterial endotoxins according to USP XXIII. d- Local limphatic ganglia sensitization assay (LLNA), according to ISO 10993-

10. e- Subcutaneous and urethral implantation test in rabbits, according to ISO 10993-6. f- The migration test at 13 weeks and 12 months. g- The bone marrow micronucleus assay developed in rats according ISO 10993-

3. h- Chromosomal aberrations in mammal cells, study according to ISO 10993-3. i- Biodegradation test pre-implant and post-implant according ISO l 0993 -13. j- Chemical Characterization of materials according ISO 10993-18.

The polymeric particles are anionic that means that they possess a highly electronegative surface. Polymeric particles with anionic surface were chosen to reduce or minimize the binding of particles to peripheral cell tissue and thus avoiding side effects in cell function.

After injection these anionic polymeric particles are coated by a fine fibrotic growth which appears within a few days, this fine fibrotic growth stabilizes the particles in the tissue site where they have been injected resulting in a stable bulking effect of the treated tissue. In a preferred embodiment, in the injectable composition according to the present application, the polymeric particles represent from 0,5 to 10 % preferably from 3 to 5% by weight of the injectable composition.

In a preferred embodiment, in the injectable composition according to the present application, the biocompatible carrier represent from 90 to 99,5 % preferably from 95 to 99,5 % by weight of the injectable composition.

Particularly the polymeric particles are chosen from anionic particles of :

• the complex of crosslinked sodium poly acrylate polymer with a copolymer of polyvinyl alcohol-polyvinyl acetate, being the copolymer of polyvinyl alcohol-poly vinyl acetate grafted onto the backbone of polyacrylate chain, preferably the copolymer of polyvinyl alcohol-polyvinyl acetate has a hydrolysis degree between 75 and 90%, and a MW comprised in the range 25-10O kDa ; • the pegylated forms of this complex of crosslinked sodium polyacrylate polymer with a copolymer of polyvinyl alcohol-polyvinyl acetate ;

• particles of crosslinked sodium polyacrylate polymer ;

• the pegylated forms of this crosslinked sodium polyacrylate polymer

• mixtures thereof. Preferably the complex of crosslinked sodium polyacrylate polymer with a copolymer of polyvinyl alcohol-polyvinyl acetate has a molecular weight comprised in the range 7000-13000 kDa, more preferably comprised in the range 9000-11000 kDa, particularly around 10000 kDa and the copolymer polyvinyl alcohol-polyvinyl acetate has a molecular weight comprised in the range 25-100 kDa, preferably comprised in the range 25-35 kDa, particularly around 3OkDa.

Before preparing the composition, the particles are subjected to different purification steps, that include successive treatments with organic solvents to remove hydrophobic impurities and highly saline and alkaline treatments to remove hydrophilic impurities in order to obtain a physiologically-biocompatible properties. The purified irregular dry particles show an average of high size diameter from 150 to 800 microns before swelling. The anionic microparticles used in this composition are swelled with a biocompatible carrier to obtain a gel structure with a lubricated surface. The carrier is added to the particles in such a way that the carrier is fully absorbed, given a composition with a semi-dried gelled structure. The anionic particles of this composition swelled with the biocompatible carrier in the condition described above : the composition according to the invention is in the form of swelled hydrogel particles having preferably a diameter range from 0,6 to 3 mm.

In a preferred embodiment of the present invention, the biocompatible carrier is a carrier free of pyrogenic substances, for example a hydro organic solution free of pyrogenic substances (e.g. : the carrier contains water (60%) and 40% of some organic molecule such as glycerol or PEG) Preferably the pH of the carrier is approximately of 6.

In a first embodiment, the biocompatible carrier is glycerol in a concentration from 15 to 60%, preferably from 30 to 50% in distillated water or isotonic saline solution.

In a second embodiment the biocompatible carrier is polyethyleneglycol in a concentration from 15 to 60%, preferably from 35 to 50% in distillated water or isotonic saline solution. In a third embodiment the biocompatible carrier is polyethyleneglycol with a molecular weight from 200 to 1000 Daltons.

In a preferred embodiment of the present invention, the purified anionic particles of this composition are partially compressible, deformable under pressure. This property makes these particles able to be injected (injectable) through needles of about 16 to 30 gauges.

In a first embodiment, the swelled hydrogel particles, after passed through a 23- gauge needle, are in the range from 10 to 1200 microns, preferably around 300 microns.

In a second embodiment, 85 to 95% of the swelled hydrogel particles, after passed through a trans-uretheral catheter of 33 cm with a 23 -gauge needle, are in the range from 100 to 1200 microns.

In a third embodiment, at least 30% of the swelled hydrogel particles, after passed through a trans-uretheral catheter of 33cm with a 23-gauge needle, are in the range from 400 to 1200 microns.

The present invention also deals with a method for preparing the injectable composition by mixing polymeric, water-insoluble, water swellable, non- biodegradable, anionic particles of irregular shape and a biocompatible carrier with a lubricated surface.

Preferably, the injectable composition according to the invention is prepared with polymeric particles chosen from particles of the complex of crosslinked sodium polyacrylate polymer with a copolymer of polyvinyl alcohol-polyvinyl acetate in a pegylated form and of the crosslinked sodium polyacrylate polymer in a pegylated form wherein the pegylation specifically occurs on the carboxylic groups of the polymers.

More preferably, the pegylation of the carboxylic groups takes place by addition of PEG-hydrazide, an activated form of polyethylenglycol where the hydrazide group allow carboxyl pegylation selectively in presence of N₅N¹- dicyclohexylcarbodiimide (DCC), or in presence of a water soluble coupling agent such as N-(-3 dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC).

Particularly the pegylated polymer contains from 1 % to 90% of the carboxylic groups of the total of carboxylic groups are in pegylated form. Particularly, the molecular weight of polyethylenglycol and of PEG-hydrazide are in the range between IK and 3OK.

The in vivo studies dealing with the injection of these anionic microparticles show that little or non change in the bulk size take place after injection, this demonstrates that this composition does not swell after implantation in tissues. In a preferred embodiment of the present invention, theses anionic particles are not capable of being hydrolyzed or removed from the site of injection by elements of the immune system like macrophage cells, or by the lymphatic system. The present invention also provides for a kit for tissue bulking where the injectable composition is ready to use in a prefilled syringe and a method to sterilize it. The anionic microparticles swelled with biocompatible carrier to obtain a semi-dry gelled structure were loaded into a 1 ml syringe in which the needle was replaced by a removable cap of silicone. The syringe containing the composition was sealed into a double pouch bag and sterilized by heating between 121⁰C to 132 ⁰C during 20 to 30 minutes.

The third object of the present invention is a method for treating a tissue in a patient, this method comprises injecting into the tissue site the injectable composition according to the invention as a permanent implant, particularly this method consists in bulking the tissue site. In a first embodiment, this method consists in augmenting the tissue deficiency or replacing the tissue in the treatment of degenerative disease. In a second embodiment, this method is a method for the treatment of urinary incontinence, urinary reflux disease, vesico-urethral fistula, fecal incontinence and gastroesophageal reflux disease.

In a third embodiment, this method is a method for the reconstruction of parts of the body such as breasts, buttocks, lips, scars.

In a fourth embodiment, this method is a method for the treatment of arthritis and arthrosis in mammals.

A fourth object of the present invention is the injectable composition according to the present invention as a medicament, particularly the injectable composition is used for the manufacture of a medicament for bulking a tissue site.

In a first embodiment, the injectable composition is used for the manufacture of a medicament for augmenting the tissue deficiency or replacing the tissue in the treatment of degenerative diseases.

In a second embodiment, the injectable composition is used for the manufacture of a medicament for the treatment of urinary incontinence, urinary reflux disease, vesico-urethral fistula, fecal incontinence and gastroesophageal reflux disease.

In a third embodiment, the injectable composition is used for the manufacture of a medicament for the reconstruction of parts of the body such as breasts, buttocks, lips, scars. In a fourth embodiment, the injectable composition is used for the manufacture of a medicament for the treatment of arthritis and arthrosis in mammals.

Reports of clinical treatments indicate that particles less than about 60 μm of diameter can be engulfed by macrophages and transported to lymph nodes.

Particles greater than 60 μm, however, have not been observed within the cell or within lymph nodes. It has been mentioned that particles with diameter higher than

80 μm appear safe from initiating such body reactions. According to R. Dmochowski (Bulking agents make resurgence in use for urinary incontinence. The BBI Newsletter, July 2002, pp 191) the size of particles must be higher than 100 μm or instigate adhesion to host tissue.

According to the present invention, the size of the particles swelled at 4% (p/v) with biocompatible carrier after extrusion through a catheter of 33 cm containing at the end a 23 gauge needle shows a high size diameter average comprised between

250 μm to 350 μm and preferably around 300 μm.

From data of the granulometric analyses of particles size it was observed that 30 % of particles have a size above to 400 μm (85 % to 95 % have a size greater to 100 μm). Taken together these results demonstrate on the one hand the elasticity and deformability of the particles and, on the other hand, that the microparticles used according to the invention are not capable of being hydrolyzed or eliminated by elements of the immune system like macrophage cells, or by the lymphatic system

The non-biodegradable microparticles of this composition are also thermally stable which allows to heat the preparation between 121°C to 132 ⁰C during 20 to 30 minutes, this heating treatment is known as sterilization by autoclaving.

The in vivo studies consisting in injecting this composition of a semi-dried amorphous hydrogel particles in different tissues shows that the bulk does practically not swell even after 3 months (after injection). Without wishing to be bound to a theory, the absence of swelling of the composition according to the invention could be explained by at least two different ways:

- the injection of this composition into tissues e.g. urethral walls, avoid the contact of the microparticles with fluids and, - after 24 or 48 hours the microparticle bulk was found to be coated by a layer of fibrin, which finally was transformed in a thin layer of fϊbrotic growth. This coating could act as a rigid basket maintaining together the bulk of injected microparticles in its initial size.

In conclusion, the application of this permanent implant in the treatment of urinary diseases show these advantages:

1- The composition comprising the anionic irregular microparticles passes through a gauge needle, the microparticles clump together in a continuous jelly stable structure with a lubricious surface which is easy to inject.

2- The jelly structure of the microparticles may be injected through 16-30 gauge needle.

3- The highly electronegative surface of this composition avoids a direct binding with tissue cells, consequently the potential side effects of its interaction is avoided.

4- The composition shows a stable tissue bulking that remains essentially unalterable with the time because : the high size of particles can not be affected by immune or lymphatic system and the injected material is coated with a natural fibrotic growth . EXAMPLES

Example 1- purification of anionic microparticles

In order to assess the physiologically-biocompatible properties of the anionic microparticles, a process is described by which the amorphous polymeric particles are treated in different steps with organic and aqueous solvents in order to remove hydrophobic and hydrophylic impurities. 1- To a sample of 10 g of dry anionic microparticles of the complex of crosslinked sodium polyacrylate polymer with a copolymer of polyvinyl alcohol-polyvinyl acetate 200 ml of chloroform were added and the mixture is incubated at 45 ⁰C under continuous stirring during 2 hours. Then the chloroform was discarded, and the procedure was repeated three times.

2- In the next step, the microparticles were treated with 200 ml of chloroform- ethanol (2:1 vol/vol) in similar conditions as describe for chloroform alone. 3- The microparticles were treated with 200 ml of ethanol similar conditions as describe before.

4- The particles were treated three times with 200 ml of dimethylsulfoxide

(DMSO) at 45 ⁰C during 2 hours each.

These procedures were done to assure to remove the hydrophobic impurities. 5- To remove the hydrophilic impurities, the particles were incubated with 500 ml of a solution containing 3 M NaCl and 0,2 M NaHO, during 6 to 12 hours at temperature from 4 to 20 ⁰C.

6- The particles were washed at least 14 times with 5 liters of tri-distillated water to remove the salt and reach a pH that ranged between 6 and 7. 7- To dry the purified amorphous particles, successive additions of ethanol, and acetone were done and finally the sample heated to 70 ⁰C for at least 6 hours to dryness.

Example 2- preparation of injectable suspension of anionic and amorphous microparticles.

The dry particles (10 g) purified as described in Example 1 were re-suspended with 500 ml of the sterile biocompatible carrier composed of glycerol-sodium chlorate (30-70 vol/vol). The suspension of particles was gently mixed during 15 minutes to obtain an homogeneously distribution of the carrier. The sample was allowed to stand for 24 hours and then loaded on the 1 ml syringe and the top was sealed with a silicon cap. Finally the syringes are sterilized by heating between 121⁰C to 132⁰C during 20 to 30 min.

Example 3- Injection of crosslinked sodium polyacrylate polymers, for in vivo bulking

2 years old female dogs were used in the assays, they were anesthetized with alothane.

To implant the microparticles in the urethral wall, an endoscopy of 20 Fr with a optic of 30 degree was used. In order to make the injection it was used a "William cystoscopic injection needle - Cook" with a 5 Fr and 35 cm long catheter and a 23 gauge needle.

Before starting the procedure, the animal vagina was washed with an antiseptic solution of povidone. To facilitate the access in urethral conducts and avoid the mucosal lesions, a 2% xilocaine gel was used. The endoscope was introduced to reach the bladder, and the bladder neck and uretheral conduits were controlled. At 1 cm of the neck of bladder, the 23 gauge needle was pushed and inserted into the urethral wall. The samples were injected at hours 3, 6 and 9 with a sample volume to close completely urethral conduit. To avoid that the material leaves the injection site, the needle was allow to stay for 20 seconds. After the injection of the microparticles, the endoscope must not be reintroduced into the bladder to avoid the flattening of the bulks.

Endoscopic observations and ecography analysis to 3, 6, 9 and 12 months were used to evaluate the bulking agent treatment. The post-images of the implant show a substantial reduction in the lumen of the urethra. The endoscopic observations and the ecography showed that the microparticle bulks stayed stable during time of the study (12 months). The volume of the injected microparticles did not present significative changes. The anatomopathological studies of the injected tissue shows:

1) No foreing body reactions, inflammation or infections were seen.

2) 48 hours after injection, a thin fibrotic tissue appear on the particles, it covers the injected particles and protect them from migration from urether to other tissues

3) No particles were observed 12 months after injection, in the anatomopathological study. After a very complete observation of all the organs (heart, urethra, lungs, liver, intestine, kidneys, glandula suprarrenalis, spleen, lymph node, pancreas, encephalon, ovary, oviduct, uterus), no dangerous migrations have been observed.

Claims

1 . Injectable composition which comprises polymeric, water-insoluble, non-biodegradable, anionic particles, these particles having an irregular shape and a biocompatible carrier with a lubricated surface, wherein said composition is injectable through needles of about 16 to 30 gauges.

2. Injectable composition according to claim 1 wherein the polymeric particles represent from 0,5 to 10 % preferably from 3 to 5% by weight of the injectable composition.

3. Injectable composition according to claim 1 or 2 wherein the biocompatible carrier represent from 90 to 99,5 % by weight of the injectable composition.

4. Injectable composition according to one of the preceding claims wherein the polymeric particles are chosen from particles of the complex of crosslinked sodium polyacrylate polymer with a copolymer of polyvinyl alcohol-polyvinyl acetate ; the pegylated forms of this complex of crosslinked sodium polyacrylate polymer with a copolymer of polyvinyl alcohol-polyvinyl acetate ; particles of crosslinked sodium polyacrylate polymer ; the pegylated forms of this crosslinked sodium polyacrylate polymer or mixtures thereof.

5. Injectable composition according to the preceding claim wherein the complex of crosslinked sodium polyacrylate polymer with a copolymer of polyvinyl alcohol-polyvinyl acetate has a molecular weight comprised in the range 7000-13000 kDa, preferably comprised in the range 9000- 11000 kDa, the copolymer polyvinyl alcohol-polyvinyl acetate has a molecular weight comprised in the range 25-100 kDa, preferably comprised in the range 25-35 kDa.

6. Injectable composition according to one of the preceding claims wherein the polymeric particles used to prepare the composition are dry particles having a size from 150 to 800 microns.

7. Injectable composition according to one of the preceding claims wherein the biocompatible carrier is a carrier free of pyrogenic substances.

8. Injectable composition according to the preceding claim wherein the biocompatible carrier is a hydro organic solution free of pyrogenic substances.

9. Injectable composition according to the preceding claim wherein the biocompatible carrier is glycerol in a concentration from 15 to 60%, preferably from 30 to 50% in distillated water or isotonic saline solution.

10. Injectable composition according to claim 8 wherein the biocompatible carrier is polyethyleneglycol in a concentration from 15 to 60%, preferably from 35 to 50% in distillated water or isotonic saline solution.

1 1. Injectable composition according to claim 10 wherein the biocompatible carrier is polyethyleneglycol with a molecular weight from 200 to 1000 Daltons.

12. Injectable composition according to one of the preceding claims wherein the composition is in the form of swelled hydrogel particles having a diameter range from 0,6 to 3 mm.

13. Injectable composition according to the preceding claim wherein the swelled hydrogel particles, after passed through a 23-gauge needle, are in the range from 10 to 1200 microns.

14. Injectable composition according to the preceding claim wherein 85 to 95% of the swelled hydrogel particles, after passed through a trans- uretheral catheter of 33cm with a 23-gauge needle, are in the range from 100 to 1200 microns.

15. Injectable composition according to claim 13 wherein at least 30% of the swelled hydrogel particles, after passed through a trans-uretheral catheter of 33cm with a 23 -gauge needle, are in the range from 400 to 1200 microns.

16. Method for preparing the injectable composition according to one of the preceding claims by mixing polymeric, water swellable, water-insoluble, non-biodegradable, anionic particles of irregular shape and a biocompatible carrier with a lubricated surface.

17. Method for preparing the injectable composition according to the preceding claim wherein the polymeric particles are chosen from particles of the complex of crosslinked sodium polyacrylate polymer with a copolymer of polyvinyl alcohol-polyvinyl acetate in a pegylated form and of the crosslinked sodium polyacrylate polymer in a pegylated form wherein the pegylation specifically occurs on the carboxylic groups of the polymers.

18. Method for preparing the injectable composition according to the preceding claim wherein the pegylation of the carboxylic groups takes place by addition of PEG-hydrazide, an activated form of polyethylenglycol where the hydrazide group allow carboxyl pegylation selectively in presence of N,N'-dicyclohexylcarbodiimide (DCC), or in presence of a water soluble coupling agent such as N-(- 3 dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC).

19. Method for preparing the injectable composition according to claim 17 or 18 wherein the pegylated polymer contains from 1% to 90% of the carboxylic groups of the total of carboxylic groups are in pegylated form.

20. Method for preparing the injectable composition according to claim 18 wherein the molecular weight of polyethylenglycol and of PEG- hydrazide are in the range between IK and 3OK.

21. Method for treating a tissue in a patient which comprises injecting into the tissue site the injectable composition as a permanent implant according to one of claims 1 to 15.

22. Method for treating a tissue in a patient according to claim 21 wherein the treatment consists in bulking the tissue site.

23. Method for treating a tissue in a patient according to claim 22 wherein the treatment consists in augmenting the tissue deficiency or replacing the tissue in the treatment of degenerative disease.

24. Method according to one of claims 21 to 22 for the treatment of urinary incontinence, urinary reflux disease, vesicourethral fistula, fecal incontinence and gastroesophageal reflux disease.

25. Method according to one of claims 21 to 22 for the reconstruction of parts of the body such as breasts, buttocks, lips, scars.

26. Method according to one of claims 21 to 22 for the treatment of arthritis and arthrosis in mammals.

27. Composition according to one of claims 1 to 15 as a medicament.

28. Use of the injectable composition according to one of claims 1 to 15 for the manufacture of a medicament for bulking a tissue site.

29. Use of the injectable composition according to claim 28 for the manufacture of a medicament for augmenting the tissue deficiency or replacing the tissue in the treatment of degenerative diseases.

30. Use of the injectable composition according to claim 28 for the manufacture of a medicament for the treatment of urinary incontinence, urinary reflux disease, vesico-urethral fistula, fecal incontinence and gastroesophageal reflux disease.

31. Use of the injectable composition according to claim 28 for the manufacture of a medicament for the reconstruction of parts of the body such as breasts, buttocks, lips, scars.

32. Use of the injectable composition according to claim 28 for the manufacture of a medicament for the treatment of arthritis and arthrosis in mammals.