MXPA00001302A - TEMPERATURE-CONTROLLED pH-DEPENDANT FORMATION OF IONIC POLYSACCHARIDE GELS - Google Patents

Abstract

The present invention relates to a temperature-controlled pH-dependant formation of ionic polysaccharide gels, such as chitosan/organo-phosphate aqueous systems, and methods of preparation thereof. While chitosan aqueous solutions are pH-dependant gelating systems, the addition of amono-phosphate dibasic salt of polyol or sugar to chitosan aqueous solutions leads to further temperature-controlled pH-dependant gelation. Solid organo-phosphate salts (1-20%w/v) are added and dissolved at low temperature (10°C) within 0.5 to 4.0%w/v chitosan in aqueous acidic solutions. Aqueous chitosan/organo-phosphate solutions are initially stored at low temperatures (4°C), then endothermally gelated within the temperature range of 30 to 60°C. Chitosan/organo-phosphate solutions rapidly turn into gels at the desired gelation temperature. Gelation can be ex vivo within any receivers or molds, or in situ in animals or humans (in vivo) so as to fill a tissue defect or cavity.

Description

DEPENDENT FORMATION OF PH CONTROLLED BY TEMPERATURE OE PELES POLIS TO IONIC ARIDES. BACKGROUND OF THE INVENTION s. { a) Field of the invention The present invention relates to a temperature-controlled pfH-dependent formation of ionic polysaccharide gels, such as aqueous systems of qososan / organD-phosphate, and methods of preparing them. w < b) Description of the Prior Art £ 1 or, uitosan is a commercially available inexpensive PC, a derivative of chitin or poiifN-acetyl-glucosamine materials). Chitosan is mainly composed of O-glucosamine units, which are generated through Ja 14-15 catalyzed deacetylation of chitin, an insoluble biopolymer extracted from the hard shells of living marine animals. { fish, crustaceans, shrimp, crabs ...) or synthesized by natural organisms. { cigo icitis, fungi ...). It is expected that chitosan has good viscoelastic properties, and has adequate tissue compatibility and biodegradability, which makes it ideal for bioactive and resorbable implants. It is also known that poly-D-glucoamine chains bind potentially to a large number of proteogycan molecules and coexist with fibrous collagens to form aqueous gels. It is believed that the role of the proteoglicans within the gel is to retain water and to provide adequate viscoelasticity. It is expected that the resulting extracellular matrices offer compatible environments for cell proliferation and tissue formation, especially for skin, ligament, bone and cartilage cells. As a consequence, chitosan attracts great interest for the scaffolding or for supporting biodesigned artificial tissue materials. In addition, the derivatives of chitin and partially acetylated qultosan have been extensively investigated for therapeutic substances or implantab.es materials. The biocompatibility of materials based on quttosan has been evaluated specifically for blood, wounds and bone. The immunological and genotoxic activities, as well as the esti ulative effects on the macrophage action, have also been studied with various chitosan materials. Chitosan and its derivatives have been extensively explored for the drug delivery system through gels (Ohya Y- et al. (1993) J- Microßncapsulation, 10 (1): 1-9). It was proposed that the supply of peptides with chitosan be performed nasally. Cationic colloidal drug vehicles were proposed from the chitosan-polycaprolactone systems. Devices for healing and reconstructive wounds made of chitosan materials for open horny D wounds, periodontal and cutaneous tissues have been proposed. Chitosan was evaluated especially in bone and dura and as a hemostatic. The entrapment of living biotopes (cells, enzymes, etc ...) has been investigated with different chitosan products, however, in almost all cases, living cells have been encapsulated within the atginato / chitosan microcuentaß. The encapsulation of chondrocytes (cartilage cells) was proposed within the calcium-alginate / chitosan beads. The gelation of chitosan through polyphosphates has been promoted to encapsulate cells such as neural or musculoskeletal tissues. Generally, the chitosan-in an acid / water medium was loaded with cell suspensions, and the resulting mixture was placed in a penta-sodium phosphate-compensated tri-polyphosphate to form beads and cell-loaded chitosan capsules. The entrapment of neural cells within the chitosan beads gelled by polyphosphate has led to good cell viability but with a low proliferation rate (Ziel ski BA et al. (1994) Bio Ateriats, 15 (13) .1049-1056) . No large materials or specific tri-dimensionai materials were proposed (Zielinski B.A. et al. (1994) Bio aterials, 15 (13); 1049-1056). Polysaccharide capsules have been proposed to physiologically entrap active cells such as Langerhans Islets (US Patent No. 4)., 391, 909). The chitosan / cisplatin mixture of hydrochloride was degraded and proposed as a drug delivery system. Chitosan derivatives have been incorporated into numerous vehicle compositions or drug formulations. Chitosan materials such as wound filling materials or contraceptive products were also proposed (U.S. Patent Nos. 4,956,350 and 4,474,769). Chitosan gels were again reported as supports for immobilizing and encapsulating living biomaterials such as cells, bacteria and fungi (U.S. Patent 4,647,536). They also proposed the systems of • 3 ophthalmic drug supply of quilosano blends for gelation and in situ formation (U.S. Patent No. 5,422.1 6). In the U.S. Patent No. 4,659,700, chitosan gels were prepared from glycerol / acid / water systems as biodegradable vehicles for drug delivery. HE reported that the resulting chitosan geies remain fairly stable, keeping their Iri-dimensional form intact during • Long periods and over a wide range of temperatures, particularly between 4 and 40 ° C. Gels and gel-like materials were processed by dissolving 1.0 to 4.0% w / v chitosan within acid-water-glycerol solutions where acetic, formic or propionic acid and 10-90% glycerol ratios are preferably used, and when neutralizing with liquid bases such as sodium, ammonium and potassium hydroxides or ammonia vapors . The pH of the resulting materials of chitosan-glycerol is from approximately 7.0 pH. After neutralization, the resulting mixtures are converted into gels after formation, resulting in such gels of the interaction of chitosan, glycol and water. Apparent glycerol or water were not reported as apparent. However, it should be noted that such tri-dimensional tri-dimensional glycosol gels will only occur when the solution is previously neutralized with a base. The one-dimensional three-dimensional gels can be easily molded as well as the gei-like membranes. The role of the glycerol and chitosan-glycerol component interactions was not clarified. Gels formed in situ with ionic polysaccharides in the U.S. Patent were also proposed. No. 5,567,175. A composition can be used as a medical device for drug delivery, the application of a diagnostic agent, or the prevention of post-operative adhesions, and an aqueous liquid carrier is composed which is capable of gelling in situ. It includes at least one ionic polysaccharide, at least one polymer that forms the film, and a medicament or pharmaceutical agent, water, and optionally, a counter ion capable of gelifying the ionic polysaccharide (U.S. Patent No. 5,587,175). However, gelation is achieved by the interaction between the ionic polysaccharide and the polymer that forms the film, or by degradation of the induced counter ion of the ionic polysaccharide. Other in situ formation gels are based on the polyoxyalkylene composition (U.S. Patent No. 4,165,646) or polyoxyalkylene / polysaccharide mixture (U.S. Patent No. 5,126,141) or alginate / cation in situ mixture (U.S. Patent Nos. 4,165,618 and U.S. Pat. 5,266,326). It would be highly desirable that this be provided with a polysaccharide gel formed dependent on temperature controlled pH which could be used to encapsulate cells and cellular material while maintaining its biological activity. - ^^^ j ^^, ^ It would be highly desirable that it be provided with such a polysaccharide gel, which could maintain its solid or gel state at physiological temperature or at 37flC.

SUMMARY OF THE INVENTION It is a goal of the present invention to provide a temperature-controlled pH dependent polysaccharide gel which could be used to encapsulate cells and cellular material while maintaining its biological activity. Another goal of the present invention BS is to provide a polysaccharide gel which could maintain its solid or gel state at physiological temperature or at 37 ° C. Another aim of the present invention is to provide a method for the preparation of tai gel polysaccharide. According to the present invention there is provided a gel based on polysaccharide which comprises: a) 0.1 to 5.0% by weight of the chemical or chitosan derivative; and b) 1.0 to 20% by weight of a polyol or sugar salt selected from the group consisting of dibasic salt of mono-phosphate, mono-sulfate salt and a salt of mono-carboxylic acid of polio! or sugar; wherein said ge) is induced and stable within a temperature range from 20 to 70 * C and is adapted to be formed and / or gelled in situ within a tissue, organ or cavities of an animal or a human.

The salt can be any of the following or in any of the following combinations: a) a mono-phosphate dibasic salt selected from the group consisting of glycerol, comprising salts of glycerol-2-phosphate, glycerol 3- phosphate and L-glycol-3-phosphate; b) a dibasic mono-phosphate salt and said polyol is selected from the group consisting of histidinoi, acetol, diethylstilbestrol, indole-glycerol, sorbitol, ribitol, xylitoi, arabinitoi, erythritol, inositol, mannitol, glucitol a mixture of the same; c) a dibasic salt of mono-phosphate and said sugar is selected from the group consisting of fructose, galactose, ribose, glucose, xylosa, ramnulose, serba, eritrulose, deoxy ribose, acetose, maasose, arabinose, fuculose, fructopyranose, aceto-glucose, sedoheptulose, trebalose, tagatese, sucrose, allose, threose, xyluosa, hexose, methylthio-ribose, methylthio-deoxy-rubibulose, and a mixture thereof; d) a dibasic salt of monD-phosphate and said polyol is selected from the group consisting of palmitol-glycerol, linoleoyl-glycerol, oleoyl-glycerol, araquidoneoyl-glycerol, and a mixture thereof; and e) a glycerophosphate salt is selected from the group consisting of glycerophosphate disodium, giicerofosfatD dipotassium, giicerofDsfatD calcium, glycerophosphate barium and glycerophosphate strontium. A preferred gel according to one embodiment of the present invention is selected from the group consisting of chitosan-β-glycerophosphite, chitosan-to-glycerophosphate, chitosanoglyphosane-glycerophosphate, and qur-osano-fructose-6. -gJicerofosfato- Solid particulates or water soluble additives • 5 can be incorporated into said polysaccharide gel prior to gelation. Non-living drugs, polypeptides or pharmaceutical agents can be incorporated into said gel polysaccharide prior to gel formation. Microorganisms, plant cells, animal cells or living human cells can be encapsulated within said polysaccharide gel prior to gelation. . The gel can be formed in situ subcutaneously, intraphsequently, intramuscutantly or within biological J5 connective tissues, bone defects, fractures, articular cavities, ducts or body cavities, ocular cavity or solid tumors. The gel of the present invention can be used as a carrier to deliver pharmaceutical agents in situ. According to the present invention there is also provided a method for producing a polysaccharide gel solution of the present invention, which comprises the steps of: a) dissolving a chitosan or a chitosan derivative into an aqueous acidic solution of a pH from about 2.0 to about 5.0 to get a The aqueous polysaccharide composition having a concentration of 0.1 heb 5.0% by weight of a chitosan or a chitosan derivative; b) dissolving 1.0 to 20% by weight of a polyol or sugar salt, wherein said sai is selected from the group consisting of mono-phosphate dibasic salt, mono-phosphate salt and a • mono-carboxylic acid salt, in said aqueous poiisaccharide composition of step a) to obtain a polysaccharide gel solution, wherein said polysaccharide gel has a concentration of 0.1 to 5.0% by weight of a chitosan or a chitosan derivative, and a concentration of 1.0 to 26% by weight of a salt of a polyol or sugar, and has a pH of from about 6.4 to about 7.4. • This method must further comprise a step c) after step b), c) heating such polysaccharide gel solution to a solidification temperature ranging from about 20 ° C at about 80 ° C to the formation of a polysaccharide gel. A pharmaceutical agent can be added to the polysaccharide gel solution of step b). The method may further comprise a step i) after step b), i) distributing for gelation the solution of gßl polysaccharide in a desired receptor, either in a mold or within a tissue, organ or body cavity. The aqueous acidic solution can be prepared from organic or inorganic acids selected from the group consisting of acetic acid, ascorbic acid, saicylic acid, phosphoric acid, hydrochloric acid, propionic acid, formic acid and a mixture thereof. • The polysaccharide gel solution can be maintained in a stable non-gelled liquid form at a temperature ranging from about 0 ° C to about 20 ° C. The solidification temperature varies from about 37 ° C to about 660 ° C, or preferably about 37 ° C. The molecular weight of chitosan varies from • approximately 10,000 to 2,000,000. The polysaccharide gel is thermoreversible or thermoreversible to the pH-adjusted polysaccharide gei, where the pH of said solution of t5 gel polysaccharide is > 6.9, or when the pH of said polysaccharide gel solution is < 6.9. The solid particulate additives can be added to the polysaccharide gel solution of step b). The polysaccharide gel solution can be introduced inside • 20 of an animal or human body by injection or endoscopic administration, and gelling in situ at a temperature of about 37 * C. According to the present invention there is also provided the use of polysaccharide gel to produce materials degradable biocompatibles used in cosmetics, pharmacology, medicine and / or surgery. The gel can be incorporated as a whole, or as a component, into implantable devices or implants for repair, reconstruction and / or replacement of tissues and / or organs, either in animals or humans. The gel can be used as a whole, or as a component of implantable, transdermal or dermatological drug delivery systems. The gel can be used as a set, or as a component of drug delivery systems or ophthalmological implants. The gel can be used to produce artificial matrices loaded with cells that are applied to the engineering and culture of bio-engineered hybrid materials and their equivalent tissues. The loaded cells can be selected from the group consisting of chondrocytes (articular cartilage), fibrochondrocytes (meniscus), ligament fibroblasts (ligament), cutaneous fibroblasts (skin), tenocytes (tendons), iofybroblasts (muscle), mesenchymal stem cells Evil and keratinocytes (skin). The cell-laden gel and the by-products are dedicated to the culture and design of artificial articular cartilage and cartilaginous tissues and organs, either for surgical or laboratory test applications. The gel loaded with cells and the byproducts are dedicated to the processing and dissection of live artificial substitutes for ligaments, tendons, skin, bone muscles and any metabolic organ, either for surgical or laboratory test applications. The gel loaded with cells and derived products are applied as live substitutes for the replacement of joint cartilages, fibrocartilages, cartilaginous organs, ligaments, tendons, bone tissues or skin. The cell-loaded hydrogel is gelled in situ to induce an ectopic formation of fibrocartilage-like or cartilage-like tissues. In accordance with the present invention, there is provided • also the use of polysaccharide gel loaded as injectable or implantable gel biomaterials which act as supports, vehicles, reconstructive devices or substitutes for tissue formation 15 in situ or bone-like, fibrocartilage-like or cartilage-like in a location physiological of an animal or a human. The polysaccharide gel solution can be used to produce a gel or hydrogel derivative ai) incorporate and dissolve at least one complementary polymer within said gel solution • 20 polysaccharide, and 2) by allowing said polysaccharide and complementary polymer to interact for a sufficient period of time to return a clear three-dimensional gel, within a temperature range of between 20 ° C to ßf C. The complementary polymer does not is a soluble polysaccharide 25 in nonionic water or a hydroxyalkyl cellulose.

For purposes of the present invention, the following terms and expressions are defined below. The term "polysaccharide gel solution" is intended to mean a pofisaccharide solution in a non-liquid form. • 5 stable gel at a temperature ranging from about 0 * C to about 15 * C, which can be melified or changed to a gel state when heated to the gelation temperature. It is intended that the term 'gelation temperature' means any temperature that ranges from approximately * C to about 80 * C, preferably from 37 * C to about 60 * C, and more preferably at about the physiological temperature or 37 ° C. It is intended that the expression "salts of polyols or i5 sugars" means di-folasic salts of mono-phosphate, salts of mono-sulfate and mono-carboxylic acid salts of polyoids or sugars The present invention includes the method of formation of different ateria gelled, either by molding those materials (in customary shapes, tubes, membranes, films ...) or forming in situ within biological environments (filling of tissue defects). In a preferred embodiment, the aqueous solution of chitosan / organophosphate has a pH above the pKa of chitosan and becomes a solid gel after thermal stimulation.

This polysaccharide gel can be used as a vehicle for drugs or as non-living therapeutic delivery systems, as substitute materials for tissues and organs and as encapsulants for living cells or microorganisms. The dies gel dies chitosan / organophosphate matrices are rapidly formed at temperatures between 30 to 60 * C. 3 The aqueous systems of chitosan / organD-phosphate are used as injectable, injected and gelled in situ filling materials to fill and repair tissue defects. Limes based on glycerel-2-phosphate, glycero-3-phosphate and glucose-1-phosphate are the preferred salts described according to the present invention. The chitosan / polyDl- or sugar-phosphate gels and • Quiosan / polyol- or sugar-sulfate can be applied to surgical reconstructive and regenerative uses and for drug delivery purposes. They provide thermally reversible or irreversible polymer gels 15 bioerosion with biologically well-known and compatible components for a wide range of medical / biofechnological applications.

BRIEF DESCRIPTION OF THE DRAWINGS • 20 Figure 1 illustrates the occurrence of the thermally controlled transition from solution to OeJ (gel formation) dependent on the pH of the aqueous solution of chitosan / glycerophosphonate characterized by the concentration of chitosan (% by weight), the concentration of glycerophosphate. { % by weight) and the pH of the solution aqueous chitosan / glycerophosphate; Figure 2 illustrates the Solution / Ge! for the systems of chitosan / glycerophosphate presented as a ratio between the molar content in the glycofosphate and the ratio of the molar content of glycerophosphate to the molar content of units of glycosamine; Figure 3 illustrates the transition from Gel Solution to Gel) induced by heat and followed by temperature by rheological measurement of the modules and viscosity parameters; Figure 4 illustrates the microstructures of chitosan / glycerophosphate gels or formed in vitro seen as observed by Scanning Electron Microscopy in gel samples that have been dehydrated by freezing at -30 ° C and for 8 hours; and Figure 5 illustrates the solutions of chitosan / glycerophosphate which are injected into rabbits, subcutaneously and inra-articularly in legs or subcutaneously in the torso, and which are allowed to gelify in situ at body temperature.

DETAILED DESCRIPTION OF THE INVENTION The q? Itosano is dissolved in acidic aqueous solutions to obtain clear aqueous q? -osan solutions having pH levels within the range of 4.3 to 5.6. Chitosan solutions can be sterilized through filtration or autoclaving by steam, and stored at a low positive temperature (4 ° C). The organophosphate component is added to the chitosan solution, preferably at a low positive temperature (4 ° C), then the aqueous chitosan / organophosphate mixture is gelled thermally, through an endothermic mechanism, within the range of temperature from 30 to 60 * C. Once formed, the resulting chitosan / organophosphate gels are thermally stable when heated. Even IßO ^ C suffices (in an autoclave), particularly in cell culture medium. Bio-encapsulation within chitosan / organophosphate gels is obtained by incorporating the living cells into the aqueous chitosan / organophosphate solution without gelling at a low temperature (4 * C). Then, the temperature of the resulting mixture of chitosan / organophosphate / cells is raised and maintained at 37 ° C where the gelation occurs in 1 hour, the organo-sulfates or the mono-carboxylic acid salt of polyols or sugars play a role. paper similar to organophosphates. Chitosan and its derivatives are relatively cheap and commercially available materials and represent an attractive group of biocompatible and degradable polymers. They have solid or solution properties that can be modified by changing their chemical composition and / or physical-chemical characteristics. It has been shown that the degree of deceleration and low weight greatly influence the properties of solution, enzymatic degradability and biological activity. Chemical modifications, for example, have been proposed to neutralize or modify the chitosan chains by the incorporation of carboxylic acid, acetate, glutamic acid, carboxymethyl or sulfate groups. The chemical degradation (anhydride, glutaraldehyde, succinate of gluta-ato-PEG ...) of chitosan macromolecules induces covalent bonds for • 3 create branched or grafted networks. The physical gelation of chitosan and its derivatives can be obtained through different techniques: a) neutralization (NaOH, KOH, NH OH ...), which induces hydrogen bonding between chitosan chains; 10 t > ) Ionic acompJejamiento with divalent anions (borate, molybdate, pDlifDsfato, salts of sujfato and sulphated macro oceans ...), which • induces electrostatic, pure interactions; c) complexing with anionic surfactants (sodium alkyl sulfate ...), which induces electrostatic interactions in hydrophobic interactions surfactant-surfactant agent. According to the present invention, a new gelation mechanism is proposed which combines hydrogen bonding, electrostatic interactions and hydrophobic interactions. • 20 chitosan-chitosan. It can only be achieved through complex interactions between chitosan macromolecules, water molecules and dibasic mono-phosphate salts of polyols or sugars. Polyols are frequently added to 25 compositions to improve gel properties. Sorbitol and mannitol are currently used as agents that improve tonicity. The glycerol and polyethylene glycol are proposed as plasticizers. The polyols (-ol: glycerol, sorbitol ...) and sugars (-ose: fructose, glucose, galactose) were used as thermal stabilizers for proteins in solutions (Back, JF Bt al. (1979) Bwchem? Stry, 18 (23): 5191-5196). Depending on the selected molecules, they were found to make or interrupt the water structuring, create the hydrogen bond, present electrostatic or hydrophobic interactions, and present IB endothermic transitions (Back, J. F. Bt? /. (1979) BiochBmistry, 18 (23): 5191-5196). Polyols and sugars stabilize proteins • to heat the denaturation through its structuring effect in water and the strengthening of hydrophobic interactions. The disodium or calcium salt of beta-glycerol phosphate or salt disodium or calcium glycerDl-2-phosphate, is a molecule well studied in biological sciences. It is considered as a substrate for alkaline phosphatase (AL). Glycerophosphate is widely used as a supplement to the cell culture medium to culture cells isolated from musculoskeletal tissues, and it has been shown that • 20 induces or maintains the synthesis of specific matrix components when supplied to bone / cartilage cells in culture (Chung C.-H et al., (1992) CalcJf, Tissue MF, 51: 305-311: Bello's CG et al. al. (1992) Bone and Mineral, 17: 15-29). The gelation of chitosan will occur with any grade or purity of glycerophosphate while the encapsulation of living biologics will require glycerophosphate tested from cell culture. The disodium or calcium aai of alpha-glycerophosphate, or disodium or calcium salt of glycerol-3-phosphate is also an organic salt of biological importance (Chung C.-H et al. (1992) Caldf. Tiss? E fot, 51: 305-311 - The glycerophosphate salts are precipitated • 5 from glycerophosphoric acids, which are obtained through the -hydrolysis of lecithin, a well-known biological molecule of egg fesfatides, soybean and fish. The glycosophosphoric acids are present under two isomeric structures, alpha and beta, in which the beta-glycerophosphoric acid is optically Inactive and the alpha-glycerophosphoric acid is optically active. Glycerophosphoric acid is a physiologically active compound that • includes carbohydrate catabolism. Glycerophosphate dehydrogenase was also found active in nerve tissues while it was reported that glycerophosphate accelerates the speed of decolonization of blue methylene by nerve from guinea pig. Alpha-glycerophosphate interacts with pyruvic acid through oxidation -reduction reactions to produce lactic acid in fresh muscle extracts. Glycerophosphoric acid is currently available under disodium, calcium, magnesium salts, • 20 dipotasio, strontium and barium, having a relatively strong basic character. Both salts, aJfa- and beta-glycerophosphate, are sources of easily available, organic, mono-phosphate dibasic salts, cheap between the polyol phosphate or sugar salts. The solubilization of chitosan in aqueous solutions requires the protonation of the amine groups of the chitosan chains, which is achieved within aqueous solutions acidices having a pH ranging from 3.0 to 5.0. When it is solubilized, the chitosan remains soluble until a pH of about 6.2. The neutralization of the acidic chitosan solutions by alkali results in an increase in pH as well as a deprotonation of the amine groups. Neutralization of the acidic chitosan solutions at a pH above the pKa of the chitosan at approximately 6.3-6.4 results in the intersaturation of OH-HN and O-HN and water-chitosan hydrogen bonds, which induce a hydrated three-dimensional network, a chitosan gel. At a pH above 6.3-6.4, the chitosan solutions are systematically found in the normal temperature range (0-60ßG) of the chemosan gels. However, adding an organophosphate to aqueous solutions of chitosan increases the pH of the chitosan / organophosphate solutions, which remains ungelled and liquid for long periods of time even at a pH above 6.5, and up to 7.2. These aqueous neo-neutral solutions of chitosan / organophosphate (pH 6.5-7.2) will gelify when stimulated by a suitable temperature. The gelling time is controlled by the temperature. For example, a solution of chitosan / organophosphate that gels in about 30 minutes at 37 ° C, needs only about 2 minutes at 60 ° C to form a gel. It has been expected that the gelling mechanism as well as the gel characteristics are similar for all chitosan / organophosphate systems. In this way, the gelation of the solutions of chitosan / β-giicerofosfate < 3U € «« has investigated in more detail, can be considered as a typical example. The results that indicate the dependence of pH and the dependence of The gelation temperature for chitosan / β-glycerophosphate solutions is summarized in the gel-solution diagrams shown in Figures 1 and 2. In addition to the gel strength, the rheological experiments depicted in Figure 3 show only that the gelation of chitosan / ß-? or glycerophosphate solutions occurs when heated. Changes in modules that appear at approximately 60 ° C are symptomatic of the transition • From Solution to Gei and Gel formation. This temperature for gel formation will depend on the characteristics of the solution and the heating rate (activation energy required). 15 The porous structure of the chitosan / ß-gyicerophosphate gels has been evidenced by Electron Microscopy of Exploration, as shown in Figure 4. The geos have a typical microstructure with cameras of approximately 100 microns and pores of approximately 10 ichrons. Its microstructure differs from those observed in processed chemose gels by simple neutralization, where a iamin ar architecture was presented. Another important feature concerns the injectability and in vivo gelation of the solutions of healthy quito / β-glycerophosphate. Injections and gels are typically shown in figures 5 A and 5B. The black arrow in Figure 5A shows the gel formed in situ in the intraarticular area of the knee joint between the collateral ligament and the patellar tendon. The other gel forms subcutaneously between the skin and the muscles of the leg. The black arrow in Figure 5B shows the gels formed subcutaneously in • 5 sit? in the torso region. In chitosan / organo-phosphate gels, the organo-phosphate anions contribute to the degradation of the macromolecule chains of the chemical, but not in the same way that pure ionic degradation occurs during the gelation of chitosan and by divalent inorganic anions. , such as sulfate, oxalate, phosphate or polyphosphate (pyrophosphates, β-phosphates or tripolyphosphates).

• An aqueous solution of qososan instantly becomes gel in the presence of inorganic divalent anions and independently of the pH value of the solution. Besides, the The rise in temperature is an unfavorable factor for the gelation of this class of systems. In contrast, the gelation of the chitosan / organophosphate solution depends both on the final pH of the chitosan / organophosphate solution and on the temperature. Each solution of chitosan / organophosphate may not gel, Any temperature, provided that its pH remains below 6.45, and each solution of chitosan / organophosphate with pH above 6.45 can be prepared at 20 ° C, without immediate gelling and can be stored for a long time at 4 ° C without being converted in gei. At 37 ° C only chitosan / organophosphate solutions with pH above 6.9 can be set more or less quickly. It is expected that the presence of organophosphate molecules in chitosan elutions will directly affect the electrostatic interactions, hydrophobic interactions and hydrogen bonds of chitosan chains. In this way, the main interactions included in the formation of organo-phosphate chitosan gels are essentially converted; 1) chitosan-chitosan interchain hydrogen bond (CHITOSAN-O.UITGSANE); 2) electrostatic attractions of chitosan / organophosphate between the ammonium groups of macromolecule chains and the phosphate group of the organophosphate molecules (OUITOSANOSPHOSPHATE); 3) hydrophobic interactions qutDsano-quitDsanD induced through the structuring action of the polyol and sugar parts in water molecules. The structuring action of the polyol parts in water reduces the interactions of quitesane-water and therefore improves the interactions of chitosan-chitosan. The non-trivial aspect of such gelification originates essentially from the last hydrophobic interactions of chitosan induced by polyol-ag? A, which improve upon increasing the temperature (temperature-controlled gelling). At low temperatures, strong chitosan-water interactions protect hydrated chitosan macromolecules against aggregations. The removal in the heating of the cover of water molecules favors and strengthens the interactions of chitosan D-chitosan, and therefore induces the association of macromolecules. However, gelation will never occur if the first two attractions (QU1TOSANO-QU1TOSANO &QU1TOSANO-PHOSPHATE) are completely non-operational within the chitosan / organophosphate solution. This explains the pH dependence that still drives the temperature controlled gelation of the kilosan / organophosphate systems. Although such electrostatic attractions of QU1TOSANOSPHATE are present, the phosphate groups may not be the only degrading agent of the chitosan chains due to the non-compatible stearic hindrance. This significantly differentiates this mechanism from the pure ionic gelation of chitosan by divalent phosphate or polyphosphate anions. A pure ionic degradation will not be stimulated or controlled by temperature. This type of pH-dependent gelling, controlled by temperature, is specifically induced by dibasic salt of organic mono-phosphate in chitosan solution, however it can also be induced by other organic salts such as mono-sulfate salts of polyols or sugars, such as poJioJ-suJfatD or sugar-sulfate, or mono-carboxylic acid salts of polyols or sugars. For example, according to the present invention, a solution of chitosan / glucose-1-sulfate is expected to gel as a chitosan / glucose-1-phosphate solution does. It is also an object of the present invention to provide an aqueous solution of chitosan / organophosphate which can be broken down and lowered at low temperature (4ßC) and transformed at physiological temperatures into a stable chitosan / organophosphate gel., tri-dlmensional. It includes non-toxic biocompatible components for mammalian or human environments with both components and processes that have low toxicity effects with respect to living biologics and that preserve cellular viability. EJ ge] also provides good mechanical performance for long periods of time at physiological temperature and in physiological aqueous media containing amino acids, ions and proteins. The chitosan derivatives can be selected as well as process chitosan / organophosphate gels and comprise N, O-chitosan substituents. The term "organophosphate (salt)" refers herein, without limitation, to dibasic salts of polyoxy mono-phosphate or sugars, such as polybonate salts or dibasic salts of sugar-phosphate. The organo-sulfates (salt) are also referred to herein as salts of mono-sulfate-d-polyols or sugars, such as polyol-suity salts or sugar-sucrose salts. Preferred organo-phosphate salts can be selected from dibasic salts of glycerol mono-phosphate, including salts of glycerol-2-phosphate, sn-glycerol 3-phosphate and 1-glycerol-3-phosphate (alpha-glycerophosphate or beta-glycero phosphate) ), dibasic salts of histidinol mono-phosphate, aceto !, diethylstilbstrol, indoleglycol, sorbitol, ribitol, xiJitoJ, arabinitoJ, erythritol, inosphol, manitoJ, gJucitoJ, paJmitoiJ-gJiceroJ, JinoJeoiJ-gJiceroJ, oJeoiJ-gliceroJ or araquJdonoiJ-gJerol, and salts of mono-phosphate fructose, galactose, ribose, glucose, xylosa, rhamnose, serba, erythrulose, deoxy ribose, ketoane, mannose, arabinose, fuculose, fructopyranose, ketoglucose, sedoheptulose, trehalose, tagatose, sucrose, alose, threose, xylulose, hexose, methylthio-ribose or methylthio-deoxy-ribamate. Other mono-salts of interest (sulfate, carboxylate) can be derived from the same polyoles or sugars. The expression "glycerophosphate or glycerophosphate" refers here to both isomers, alpha-glycerophosphate or beta-glycerophosphate, and alpha-glycerophosphate refers interchangeably to gl cerol-3-phosphate (all optical enantiomer-β), whereas beta-glycerophosphate refers to beta-glycerophosphate. glycerophosphate is similarly referred to glycol-2-phosphate The term "dimensional" refers in the present to the fact that the polymeric solution is gelled and configured simultaneously by the mold in which the solution was initially poured. Gels can be produced in tubes, plastic or glass plates or between two plates in order to obtain any shape expected. The expression "getificación m sit?" refers herein to the formation of chitosan / organophosphate gels by injecting the liquid solution of chitosan / organophosphate within specific sites of mammalian or human environments, e.g. any tissue (muscles, bone, ligaments, cartilage) and organs. In situ gelation allows the precise and complete filling of tissue defects or body cavities. The gelation of the manganese / organophosphate mixture is induced by the physiological temperature. The term "endothermic gelling" refers herein to the thermal mechanism of the chitosan / organophosphate solution that allows the solution to gel at the desired temperature. The induction of transitions from solution to gel of the systems of qurtosan / organophosphate requires energy via, for example, temperature. The term "cells or cellular materials" refers herein to living biologics, such as isolated cells, cell dispersion, cell aggregates, cell spheroids or cells adhered to solid microsphere particles that are encapsulated in the chitosan / organophosphate gels. The term "in situ training" refers to the • present to the procedure of administering the ungelled chitosan / organophosphate liquid solution to a cerpcrai site (e.g., connective tissues, body ducts, articular cavities, fractures, bone defects ...), and to induce and ensure within the body site at physiological temperature a complete gejifica- tion of the polysaccharide solution in a geJ. Formation of chitosan / organophosphate gels The organophosphate salt selected in the present was glycerophosphate, but similar results were achieved with other dibasic mono- phosphate salts of sugars or sugars. Chitosan EJ powder is dissolved in an aqueous acidic solution until the occurrence of a clear solution is obtained. The proportion of chitosan varies from 0.5 to 5.0% weight / volume, preferably from 1.0 to 3.0% by weight / volume. The pH of the aqueous chitosan solution varies from 4.5 to 5.5. Aqueous chitosan solutions can be sterilized either by filtration with sterile filters in line (0.22 microns) or by steam autoclaving (120 ° C). The • 5 sterilization of the chitosan / organophosphate gels may not be filtered due to viscosity or not autoclaved by steam due to thermal sensitivity, but may be carried out by gamma irradiation or achieved through strictly sterile procedures. Aqueous chitosan solutions Freshly prepared preparations are preferably stored at low positive temperatures (4 * C). The glycerophosphate found in • fine powder form is added to, and dissolved within, the aqueous chitosan solution at a temperature ranging from 4 coarse to 15 ° C, preferably 10 ° C. When an aqueous solution is achieved d of chitosan / clear homogenous organophosphate with a pH ranging from 6.5 to 7.2, said solution is poured into the desired receptor, and maintained at the appropriate temperature to gel. The gyrophosphate found in the form of an aqueous solution can also be used. 20 Depending on their final pH, chitosan / glycerophosphate solutions are expected to result in either a thermally reversible or irreversible gel. Reversible gels originate from chitosan / glycerofDsfatD solutions having a pH between 6.5 and 6.9, while irreversible gels are originate from chitosan / glycerophosphate solutions having a pH above 6.9. The nature of the acid used for the acidic chitosan solutions does not fundamentally influence the transition from solution to gel of the chitosan / glycerophosphate system. The final pH inside a solution of chitosan / glycerophosphate • 5 depends on the pH of the water / acid solution as well as the concentrations of the chemical and glycerophosphate. Since chitosan and glycerophosphate are two alkaline components, they tend to increase the pH of the acidic solution where they dissolve. The concentrations in chitosan and glycerophosphate can be balanced to achieve the appropriate pH of the chitosan / glycerophosphate solution, while taking into account the limit • solubility of both components, and particularly that of chitosan. Monolithic tri-dimenßlonaleß Goals The organophosphate salt selected herein was glycerophosphate, but similar results were achieved with other mono-phosphate dibasic salts, monosulfate salts or monocarboxylate salts of polyols or sugars. The receiver or mold filled with chitosan / glycerophosphate solution is heated to a temperature ranging from 30 to 60 ° C, preferably 37 ° C. The gelation of the chitosan / glycerophosphate solution at 37 ° C can be carried out in a common cell culture incubator. The solution is maintained at the desired temperature until it becomes a gel after a period, which varies from some days up to a week (at 30 ° C) up to a few minutes (at 60 ° C). At 37 ° C, the gelation of the chitosan / glycerophosphate solution occurs in about 1 hour. Once a three-dimensional chitosan / glycerophosphate gel is formed, said gel is desmoided and rinsed in paraded water. The geies of • 5 chitosan / gJJcerofDsfalo remain stable and maintain their three-dimensional shape even at elevated temperature, 120 * C (autoclaved). High Goal Formation The organophosphate salt selected herein was glycerophosphate, but similar results were achieved with other monobasic dibasic salts, onosuphosphate salts or monocarboxylate salts of polyols or sugars. The in situ gelation of ia • Chitosan / giicrophosphate solution can be conducted by distributing the solution of a hypodermic syringe. If necessary, the solution can be pre-gelled, (initiate thermal gelation) to maintain the syringe and the chitosan / glycerophosphate solution at a desired temperature, ideally 7 * 0, until the first signs of gelation appear. The ready-to-gel mixture of chitosan / glycerophosphate is then administered to fill the cavities or defects of the tissue and complete the gelation process in situ (a 37 ° C). Without ignition, the injection of chitosan / glycerophosphate solutions is limited by the viscosity of the solutions that control the injectability or extrusibility of the solutions. A needle having a size of 20 and below are ideal materials for the injection of such a gel solution. The body cavities and tissue defects act as containers for the solution, but the liquid materials remain in an open aqueous environment. The conformation and diffusion capacity of the solutions of chitosan / glycerophosphate depends on the properties of the material and the solution. The increased viscosity results in the in situ formation of more compact and less treatable gels. Encapsulation of living biologics with fumaroles / glycerophosphate gels The organo-phosphate salt selected herein was glycerophosphate, but similar results were achieved with other mono-phosphate dibasic salts, monosulfate salts or monocarboxylate salts of polyols or sugars. Cell materials or living cells were prepared using current cell culture techniques. The cell materials or cells were incorporated and hogented at low positive temperatures ranging from 4 to 2% * C, ideally 20 * C, in the aqueous solution of chitosan / glycerophosphate. Cell materials or cells loaded with mixtures of chitosan / glycerophosphate were poured into the desired receptacles or dishes and incubated at 37 ° C. The middle cell culture supplemented or minimized was added to the dishes or receptacles containing the cellular materials or cells loaded with materials of the cytostat / glycerophosphate to keep the encapsulated living cells alive and etabically active. The cell culture medium was renewed every 2 days following the formation of the chitosan / glycerophosphate gels. The viability of the cells within the solution and the gel is potentially reduced by abnormal osmolarity. The systems of quitoßano / glycerophosphate have changing osmolerities depending on the component dß gticßrofosfato ionic. The higher the content of glycerophosphate salts, the more • 5 The osmolarity of the solution will be high, and the deterioration will be greater for cell viability. The ideal osmolarity for bioencapsulation will be around 270 to 340 mOsmol / kg. In situ injection and gelifcation of the quitoßan / glycerophosphate materials loaded with cellular materials or living cells can be determined in a manner similar. The cell materials or cells are introduced at a positive low temperature into the aqueous solutions of glycerophosphate chitosan before injection and gelation. There is a direct relationship between glycerol-2-phosphate disodium salt content and osmolarity. To reduce such problems of In the case of osmolarity, the final pH of the chitosan / glycerophosphate can be adjusted to its desired value while keeping the glycerophosphate content as low as possible. However, a low glycerophosphate content limit must be increased to process temperature-controlled pH-dependent gelation. 20 Therapeutic Use and Other Uses dies Geies Based on Chitosan A glia of chitosan / organophosphate or organD / sulfat, as previously described, is an ideal material for a drug delivery system. Such a formation vehicle similar to an in situ gel, wherein a solid particulate or a water soluble additive is incorporates before gelation, can be administered topically, directly to the body site to be treated or diagnosed. Within the composition and the gel, antibacterial, anti-fungal, anti-steroidal or non-spheroidal anti-inflammatory agents, anti-carcinogenic, anti-fibrosis, anti-viral, anti-Jucoma, miotics and anti-CDlinergic agents can be incorporated, anti-psychotic, antifungal and decongestant, anesthetic and anti-parasitic. In a similar manner, non-living polypeptides and pharmaceutical agents can be incorporated within the composition or gel for restorative, reconstructive or biosignative purposes. Microorganisms, plant cells, animal cells or living human cells can be incorporated identically into the polysaccharide gel by their introduction before gelation. Gels loaded with cells or micro-organisms can be applied for biotechnological purposes in medicine or other industrial areas. The gels of in situ formation based on chitosan can be formed subcutaneously, intramuscularly, intra-peritoneally or within biological connective tissues, bone defects, fractures, joint cavities, ducts or body cavities, ocular cavities, vasculature of solid tumors, etc ... The present invention will be more readily understood when referring to the following examples, which are given in order to illustrate the invention rather than to limit its scope.

EXAMPLE I Typical Geology of a Chitosan / Organophosphate System Experiment 1: A typical experiment was carried out by dissolving 0.2 g of chitoseno in 10 ml of aqueous acetic acid solution (0.1M). The pH of the acetic acid solution was previously adjusted to 4.0 by the addition of droplets of potassium hydroxide solution < 1M). The solution of q? Osano ai 2% (weight / volume) thus obtained had a pH of about 5.6. Subsequently, 0.800 g of glycerophosphate disodium salt pentahydrate and dissolved in the chitosan solution at 10 ° C. The pH of the homogeneous liquid mixture The resultant became 7. This mixture was placed in a glass scintillation flask in the incubator at 37 ° C for 2 hours, sufficient time to achieve the mass gelation process. EJ gel in The resulting mass was immersed in renovated bars of distilled water in order to remove the excess glycerophosphate salt. A similar result was achieved when the disodium salt of glyphosate (or disodium salt glycol-2-phosphate) was replaced by the disodium salt of alpha-glycerophosphate (or disodium salt of glycerol-3-20 phosphate). Experiment 2: A homogenized solution of chitosan / glycerophosphate was prepared as in Experiment 1 and placed in a double gel melter having a gel sandwich of plaques of glass with an interior space of 1.6 m, and the system was kept in an oven at 37 ° C. The formation of a gel membrane was reached in 2 hours and the membrane was separated from the mold of the gel melter. Experiment 3: 0.110 g of smoked silicon was dispersed under a solid particulate form (AEROSIL) in a solution prepared by dissolving 0.200 g of chitosan in 10 ml of aqueous acetic acid solution. 0.800 g of disodium glycerophosphate disodium salt pentahydrate was added to the d-chitosan-sily dispersion. The resulting composition was placed in a bottle of glass scintillation in a water bath maintained at 37 * C. The gelation of the chemical / glycerophosphate component was observed • in 2 hours and the glycerophosphate chitosan gel included solid, dispersed silica particles. Experiment 4: 15 0.200 g of chitosanD were dissolved in an acetic acid solution, as in Experiment 1. 1,239 g of glucose-1-phosphate disodium salt tetrahydrate was added and dissolved to achieve a clear chitosan solution. glucose-1-phosphate. This solution of D-chemosan / glucose-1-phosphate placed in a bottle of Twilight dß glass was maintained at 37 ° C. The transition from Solution to Gel occurred at 37 ° C at 3 hours. The resulting bulk gel was immersed in renovated distilled water baths in order to remove excess sai from glucose-phosphate. The experiment was conducted as described in Experiment 4 except that 1,239 g of glucose-1-phosphate salt was replaced by 0.100 g of disodium salt dihydrate of fructose-6-fos ato. EXAMPLE ti Effect of the composition on the pM of the solution and occurrence of the 4th stage. For all the experiments, a mother acid solution was prepared, which was done by acetone / acetic acid. The pH of this acidic mother solution was adjusted to 4.0. High molecular weight Chitosan powder (Molecular weight 2,006,600) was added and oHsolved in a volume of the mother acid solution in order to produce solutions of Quftosan that have proportions of Guitosa ro ranging from 6. 5 to 2.O% by weight volume Table 1). Tafota 1 gives you the pH measured for the different samples. labia 1 15 Aqueous Solutions of Chitosan and pH Levels • 20 Glycerophosphate was added to the chitosan solutions and an increase in pH was induced. Table 2 shows the effect of the glycerophosphate concentration on a different chitosan solution. The glycerophosphate concentration varies from 0.065 to 0.300 mol / L. Chitosan / glycerophosphate solutions in bottles glass were maintained at 60 and 37 ° C and uniform and uniform gelling was observed at 30 minutes at 60 ° C and at 6 hours at 37 ° C (Table 2 and Figure 1). The chitosan and beta-glycerophosphate components individually influence the pH increase within the aqueous solutions and, consequently, influence the transition from Solution to Gei. As well as the dissolved materials, the initial pH of the acetic acid solution / mother liquor also influences the transition from Solution to Gel, but this potential effect seems to be limited by the counter-action of the solubility of the chitosan, which depends on the pH of the solution. the solution. Iabj _2 Gelification of the Compositions of Chitosan / GlycolTofDsfato EXAMPLE 111 Thermal Reversibility of the Gelation of Chitosan / Glycerophosphate Systems A first solution of chitosan / glycerophosphate was prepared from 10 ml of an acetic acid / mother liquor solution of pH 4.0 by the addition and dissolution of 0.200 g of chitosan and 0.800 g of glycerophosphate disodium salt pentahydrate. The resulting chitosan / glycerophosphate solution has a pH of about 7.05 and is heated to 60 ° C, where it rapidly gels. The chitosan / glycerophosphate gel is cooled to a temperature of about 0-4 ° C, but no transition is observed with time and the gel remains stable at 4 ° C. This chitosan / glycerophosphate gel is thermo-irreversible. A second solution of chitosan / glycerophosphate was prepared from 10 ml of an acetic acid / mother liquor solution of pH 4.6 by the addition and dissolution of 0.100 g of chitosan and 0.800 g of glycerophosphate disodium salt pentahydrate. The chitosan / glycerophosphate solution has a pH of about 6, 78 and heated to 60 ° C for gelation, the resulting glycine / g / Phosphate ester was then cooled to a temperature of about 0-4 * C and a transition from GeJ to Solution was observed after a period of time . The gel returned to a liquid solution at low positive temperatures, for example at 4 * C. When this solution was reheated to 60 * C, the reverse mechanism appeared again (transition from Solution to Gel) and a gel formed again. The transition from Solution to Gel to Solution is reproducible between temperatures at 4 and 60 ° C. This chitosan / glycerophosphate gel is thermo-reversible. The thermo-reversibility of the solution to gel transition of the chitosan / glycerophosphate systems is predominantly dependent on the pH of the chitosan / glycerophosphate solution. An example of pH and reversibility observed is given in Lab 3. Experimental observations on the chitosan / glycerophosphate systems have shown that the thermal reversibility of the Gel Solution mechanism changes under a pH of 6.9 in the chitosan / glycerophosphate solutions in the immediate vicinity. A reversible gelation of the chitosan / glycerophosphate solutions occurs when the pH is between 6.5 and 6.9. A very similar result was observed with other dibasic mono-phosphate salts of poiols or sugars such as glucose-1-phosphate salts. Table 3 Effect of pH on Reversibility of Solution to Gel for a Concentration of Chitosan at 2.0% weight / volume EXAMPLE IV In situ gelation of chemical / glycerophosphate materials New Zealand white rabbits, adults, were anaesthetized by intravenous administration of Pentosorbite! of Sodium (1 ml / kg) and kept under anesthesia for 3 hours.

After 3 hours, the animals were sacrificed by anesthetic overdose and the experiments were continued post-mortem. The animal was kept on the back and the localized areas of the upper limbs and the torso region were shaved. Made • 5 an incision in the skin to release the subcutaneous fibrous membranes and the limbus muscle. Two solutions of chitosan / glycerophosphate were prepared beforehand, placed in tyredermic syringes and kept at a low temperature (4-10 ° C): solution 1 was a low molecular weight chitosan at 2.7% w / v and glycerophosphate at 9.0% w / v, while solution II • it was a chitosan with a molecular weight of 2.5% and a glycerophosphate of 9.0% by weight / volume. The syringes were equipped with measuring needles No, 21, Quosano / glycerophosphate solutions were not were prepared or maintained under strict sterile conditions since the experiments on the animals were carried out within a period of about 4-5 hours. A volume (a) of 1.0-1.5 ml of solution 1 was injected subcutaneously into the fibrous membranes, while a second volume (b) of 2.0 ml of solution 1 was injected through the joint capsule of the knee into the joint cavity. A volume (c) of 1.0 ml of solution 11 was injected subcutaneously into the torso region. All the injection sites were again covered with cut tissues when necessary. Gelation was allowed in site for a period of 3 hours, then the sites were re-opened or cut and the oles formed in situ were collected. Table 4 Injections and in situ training of the Gles • • EXAMPLE V Encapsulation of Mammalian Cells An aqueous solution of chitosan at 2.5% w / v was prepared, as previously described. 1.98 g of the chitosan solution were mixed with 0.18 g of the beta-glycerophosphate disodium sai, 0.4 ml of Dubelcco Modified Eagle Medium F12, where animal chondrocytes were dispersed, and 0.2 ml of Dubelcco Modifißd Eagie Medium F12. Chondrocytes were isolated from fetal shoulder cartilage surfaces and harvested from primary monolayer cultures. Dubelcco Modifißd Eaglß Medium F12 comprises dexamethasone, ascorbic acid and 10% fetal bovine serum. All the solutions of Chitosan, the solutions of Chitosan / glyceroJ-2-phosphate and procedures, were sterile.

Once the chondrocytes were melted in the chitosan / glycerol-2-phosphate dispersion, they were placed in an incubator at 37 ° C until gelation. The geli fi cation of the chitosan / glycerel-2-phosphate system was observed in 2 hours. Feasibility tests on such chitosan / glycerol-2-fophosphate geleß loaded with oondrocytes indicated a range from 10% to 70% of live chondrocytes. The encapsulation of micro-organisms, plant cells, animal cells or human cells within chitosan / glycolrol-2-phosphate geies can be carried out with changing properties, depending on the expected viability. Although the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of subsequent modifications and this application attempts to cover any variation, use or adaptation of the invention, following, in general, the principles of the invention and including such deviations from the present description as come within the known or customary practice within the matter to which the invention pertains and as they may be applied to the essential characteristics hitherto established and as it continues in the appended claims.

Claims (27)

1. RE1V1ND1CATIONS 1. A gel based on polysaccharide, characterized in that it comprises: a) 0.1 to 5.0% by weight of chitosan or a derivative of chitosan; and b) 1.0 to 20% by weight of a polyol or sugar salt, selected from the group consisting of mono-phosphate dibasic salt, mono-sulfate salt and a mono-carboxylic acid salt of polyo! or sugar: wherein said gei is induced and stable within a temperature range from 26 to 70 * C and is adapted to be formed and / or gelled in s / t? inside a tissue, organ or cavities of an animal D a human.
2. 2. A gel according to claim 1, characterized in that said salt is a dibasic salt of glycerol mono-phosphate, comprising salts of glycerol-2-phosphate, sn-glycerol 3-phosphate and L-glycerol-3-phosphate.
3. 3. A gel according to claim 1, characterized in that said sai is a dibasic mono-phosphate sai and said polyol is selected from the group consisting of ustidme! Aceto! , diethylstilbestrol, indole-glycerol, sorbitol, ribitol, xylitol, arabinitol, erythritol, inositol, mannitol, glucitol and a mixture thereof. A gel according to claim 1, characterized in that said salt is a dibasic mono-phosphate salt and said sugar is selected from the group consisting of fructose, galactose, ribose, glucose, xylose, ramnulose, serba, erythrulose, deoxy-ribose , Quetose, Maas, Arabinose, Fuculose, Fructopyranose, Ketoglucose, Sedoheptulose, Trehalose, Tagatose, Sucrose, Allose, Threose, Xylulose, Hexose, Methylthio-Ribose, Methylthio-deoxy-ribulose and a mixture thereof. 5. A gei according to claim 1, characterized in that said salt is a dibasic salt of mono-phosphate and said polyol is 5 selects from the group consisting of palmitoyl-glycerol, Unoleoilgliceroi, oieoyl-glycerol, arachidonoyl-glycerol and a mixture thereof. 6. A gel according to claim 1, characterized in that said gel composition is selected from the group 10 consists of chitosan-β-glycerophosphate, chitosan-α-glycerophosphate, kilosanD-glucose-1-glycerophosphate and chitosan-Fructose-6- • glycerophosphate. 7. A gel according to claim 1, characterized in that the solid particulate or the water soluble additives are 15 incorporate polysaccharide into said gel prior to gelation. 8. A gel according to claim 1, characterized in that non-living drugs, polypeptides or pharmaceutical agents are incorporated into said polysaccharide gel prior to gelation. 9. A gel according to claim 1, characterized in that microorganisms, plant cells, animal cells or living human cells are encapsulated within said polysaccharide gel prior to gelation. 10. A gel according to claim 1, characterized in that said gel is formed in situ? subcutaneously, intraperitoneally, intramusculary or within biological connective tissues, bone defects, fractures, articular cavities, ducts or body cavities, ocular cavities or solid tumors. 11. A gel according to claim 10, characterized in that said gei is a vehicle comprising an agent • Pharmaceutical to supply said pharmaceutical agent in situ. 12. A method for producing a polysaccharide gel solution according to claim 1, characterized in that it comprises the steps of: a) dissolving a chitosan or a chitosan derivative within an aqueous acidic solution of a pH from 10 about 2.0 to about 5.0 to obtain an aqueous pofisaccharide composition having a concentration of 0.1 • up to 5.6% by weight of a chitosan or a chitosan derivative: b) dissolving 1.0 to 20% by weight of a polyol or sugar salt, wherein said sai is selected from the group consisting of dibasic salt 15 of mono-phosphate, mono-sulfate salt and a monocarboxylic acid salt, in said aqueous polysaccharide composition of step a), to obtain a polysaccharide gel solution, wherein said polysaccharide gel has a concentration of 0.1 to 5.0 % by weight of a chemical or a derivative of a chemical and a concentration of 1.0 to 20% by weight of a salt of a polyol or sugar, and has a pH of about 6.4 to about 7.
4. 4. The method according to claim 12, characterized in that it further comprises a step c) after step b), c) heating said polysaccharide gel solution to a The solidification temperature varies from about 20 ° C to about 80 ° C until the formation of a polysaccharide gel. 14. The method according to claim 12 or 13, characterized in that a pharmaceutical agent is added to the solution • 5 polysaccharide gel from stage b). The method according to claim 13 or 14, characterized in that it further comprises a step i) after step b), i) supplying the polysaccharide gel solution in a desired receptor for gelation, either in a mold or in a a 10 tissue, organ or body cavity. 16. The method according to claim 12, 13 or 14, • characterized in that said aqueous acidic solution is prepared from organic or inorganic acids selected from the group consisting of acetic acid, ascorbic acid, salicylic acid, acid 15 phosphoric acid, hydrocyclic acid, propionic acid, formic acid and a mixture of the same. 17. The method according to claim 12, 13 or 14, characterized in that said salt is a dibasic salt of glycero mono-phosphate, wherein said glycerol is selected from the group consisting of salts of glycerol-2-phosphate, glycerol 3-phosphate and L-glycerol-3-phosphate. The method according to claim 17, characterized in that said glycerophosphate salt is selected from the group consisting of glycerophosphate disodium, dipotassium 25 glycerophosphate, glycerophosphate calcium, glycerophosphate barium and glycerophosphate strontium. The method according to claim 12, 13 or 14, characterized in that said salt is a dibasic mono-phosphate salt of a polyol, and said polyol is selected from a group comprising • histidinol, acetol, diethylstilbeestol, indolglycerol, sorbitol, ribitol, xylitol, arabinitol, erythritol, inositol, mannitol, glucitol and a mixture thereof. The method according to claim 12, 13 or 14, characterized in that said salt is a dibasic salt of mono-phosphate 10 of a sugar, and said sugar is selected from a group comprising fructose, galactose, ribose, glucose, xylose, ramnulose, werba, erythrulose, deoxy ribose, ketosa, maasose, arabinose, fuculose, fructopyranose. ketoglucose, sedoheptulose. trehalose, tagatose, sucrose, allose, threose, xylosis, hexose, metfltio-rifoose, methylthio-15 deoxy-rubose and a mixture thereof, according to claim 12, 13 or 14, characterized in that said The salt is a dibasic salt of monophosphonate of a polio, and said polio is selected from the group consisting of glycolol, glycerol, hydrochloride, glycerol, arachidonoyl glycerol and a mixture thereof. 22. The method according to claim 12, 13 or 14, characterized in that said salt is a dibasic mono-phosphate salt and said phosphate is selected from the group consisting of phosphate disodium, phosphate dipotassium, phosphate calcium, phosphate barium Y 25 phosphate strontium. 23. The method according to claim 12, characterized in that said polysaccharide gel solution is maintained in a stable ungelled liquid form at a temperature ranging from 0 ° G to 20 ° C. 24. The method according to claim 13, characterized in that said solidification temperature varies from 37 * C to 60 ° C. 25. The method according to claim 24, characterized in that said solidification temperature is about 37 ° C. 26. The method according to claim 12, 13 or 14, characterized in that the molecular weight of the qososan varies from 10,600 to 2,000,000. 27. The method according to claim 12, 13 or 14, characterized in that the polysaccharide gel is thermoreversible or thermoreversible by adjusting the pH of the polysaccharide gel.