JP6176998B2 - Temperature-responsive biodegradable polymer composition and method for producing the same - Google Patents

Description

  The present invention relates to a temperature-responsive biodegradable polymer composition and a method for producing the same.

  Many studies have focused on the physicochemical response of stimuli-responsive polymers to changes in temperature, pH, electric field, and chemicals. In particular, temperature-responsive polymers that exhibit a phase transition phenomenon in response to external temperature changes have been widely studied as medical materials such as drug carriers.

  The homopolymers or copolymers of N-isopropylacrylamide (NIPAAm) disclosed by Non-Patent Documents 1 and 2 are one class. Another class is from hydrophobic poly (propylene oxide) as the middle block and hydrophilic poly (ethylene oxide) as the side block, such as, for example, Pluronic (Poloxamer ™) disclosed by Non-Patent Document 3. This is a triblock copolymer. This triblock copolymer exhibits a behavior of transition from a solution state (sol) to a gel state containing a solvent in response to temperature (hereinafter referred to as sol-gel transition). This is because a copolymer aqueous solution having a specific molecular weight and composition range exists as an aqueous solution at a temperature lower than the sol-gel transition temperature, but when the temperature is higher than the transition temperature (for example, when the temperature rises to body temperature), This is a phenomenon in which an insoluble gel is formed by the interaction between coalesces. These polymers, which can be converted in situ from sol to gel, can be used as medical materials that can be administered by injection into the body. At the time of administration and after administration, there is an advantage that an implant of any desired shape can be formed in a living body minimally invasively without the need for surgical treatment. In other words, a gel containing a physiological (pharmacologically) active substance can be easily prepared by injecting a physiological (pharmacologically) active substance and a polymer solution into the body. It is possible to release. Moreover, the gel which took in the cell easily can be prepared by injecting into the body what suspended the suitable cell in the polymer solution.

  In this way, materials that gel in situ are attracting attention as implantable drug delivery systems that can be implanted in vivo by injection or as matrices for tissue engineering. In order to function as an ideal injectable system, an aqueous solution of the polymer must exhibit a viscosity that is low enough to be injectable under the preparation conditions and must gel rapidly under physiological conditions (around 37 ° C.). When considered as a medical material, the biocompatibility and safety of the polymer are also important issues. For this reason, the material must be decomposed to a molecular weight that is biodegradable, metabolizable, or excreted outside the body without developing toxicity. In addition, during the decomposition, it is necessary not to induce irritation of living tissue by maintaining the properties of hydrogel rich in water content.

  However, poloxamer-type copolymer (Pluronic) is non-biodegradable, and animal experiments have shown that triglycerides and cholesterol increase when an aqueous solution of poloxamer is injected intraperitoneally (Non-patent Document 4).

  Recently, in Non-Patent Document 5, a copolymer of polylactic acid (PLA) and polyglycolic acid (PGA) (hereinafter also referred to as PLGA) that is biodegradable and gels in response to temperature in situ. A triblock copolymer composed of polyethylene glycol (PEG) (hereinafter also referred to as PLGA-b-PEG-b-PLGA, also simply referred to as PLGA-PEG-PLGA) has been reported.

  However, the above-mentioned PLGA-b-PEG-b-PLGA is a viscous liquid at room temperature and in the absence of solvent, and thus has problems in operability such as dispensing (dispensing) and weighing. In addition, when PLGA-b-PEG-b-PLGA is dissolved in a medium containing water such as water or phosphate buffered saline (PBS) to form an aqueous solution, it takes a very long time. Therefore, there is a problem that it is difficult to immediately dissolve and use (prepare at the time of use) when necessary in a medical site such as a hospital or a clinic.

  In order to solve such problems, it has been studied to make the powder (solidification) by drying the PLGA-b-PEG-b-PLGA. There is a problem that it cannot be solidified into powder.

  Therefore, it is a biodegradable polymer composition that exhibits a sol-gel transition in response to temperature, can be in a solid state, and dissolves in a short time when dissolved in a medium containing water. Development of a biodegradable polymer composition that can be applied is desired.

Bae et al. Makromol. Chem. Rapid Commun., 8, 481-485 (1987) Chen et al. Nature, 373, 49-52 (1995) Malston et al. Macromolecules, 25, 5440-5445 (1992) Wout et. Al, J. Parenteral Sci. & Tech., 46, 192-200 (1992) Doo Sung Lee, Macromol. Rapid Commun. 2001, 22, 587.

  The present invention is a biodegradable polymer composition that exhibits a sol-gel transition in response to temperature, can be made into a solid state, and dissolves in a short time when dissolved in a medium containing water. It is an object of the present invention to provide a biodegradable polymer composition that can be used.

As a result of intensive studies to achieve the above object, the present invention produces a composition containing specific components for a triblock copolymer containing PLGA such as PLGA-b-PEG-b-PLGA. In some cases, the inventors have found that the above object can be achieved and have completed the present invention.
1. Below (1) and (2):
(1) A-B-A type or B-A-B type triblock copolymer,
The A segment comprises poly (lactic acid-co-glycolic acid);
The B segment comprises polyethylene glycol;
The triblock copolymer, and
(2) A temperature-responsive biodegradable polymer composition comprising sucrose and / or lactose.
2. The temperature-responsive biodegradability according to Item 1, wherein the content of the (2) sucrose and / or lactose is 25 to 100 parts by mass with respect to 100 parts by mass of the (1) triblock copolymer. Polymer composition.
3. The A segment constitutes 30 to 75% by mass of the (1) triblock copolymer,
Item 3. The temperature-responsive biodegradable polymer composition according to Item 1 or 2, wherein the B segment constitutes 25 to 70% by mass of the (1) triblock copolymer.
4). Below (1) and (2):
(1) A-B-A type or B-A-B type triblock copolymer,
The A block comprises poly (lactic acid-co-glycolic acid);
The B block comprises polyethylene glycol,
The triblock copolymer, and
(2) A method for producing a temperature-responsive biodegradable polymer composition containing sucrose and / or lactose, the following (i) and (ii):
(i) Step 1 for producing the above triblock copolymer by polymerizing lactide and glycolide in the presence of polyethylene glycol, methoxy-polyethylene glycol or aliphatic diol, and
(ii) Step 2 of dissolving the (1) triblock copolymer and the (2) sucrose and / or lactose in a solvent,
In order, The manufacturing method of the temperature-responsive biodegradable polymer composition characterized by the above-mentioned.
5. Step 3 of bringing the polymer composition into a solid state by drying the temperature-responsive biodegradable polymer composition obtained in Step 2.
The manufacturing method of the temperature-responsive biodegradable polymer composition of said claim | item 4 containing said.

<< 1. Temperature-responsive biodegradable polymer composition >>
The temperature-responsive biodegradable polymer composition of the present invention includes the following (1) and (2):
(1) A-B-A type or B-A-B type triblock copolymer,
The A segment comprises poly (lactic acid-co-glycolic acid);
The B segment comprises polyethylene glycol;
The triblock copolymer, and
(2) It contains sucrose and / or lactose. Therefore, the temperature-responsive biodegradable polymer composition of the present invention exhibits a sol-gel transition in response to temperature. In particular, it has a feature that it can be gelled at a temperature between room temperature and body temperature. Therefore, it is possible to provide an excellent in situ gelation system, eliminate the need for surgical treatment, and form an implant with minimal invasiveness by injection. Since physiologically (pharmacologically) active substances and the like are stably encapsulated and can be sustainedly released in the body, an injectable (injectable) drug delivery system can be provided. Furthermore, it can also be used as a scaffold for injectable tissue repair and organ regeneration, or in a cell delivery system or the like for transplanting cells into a defect site of in vivo tissue by injection administration by encapsulating suitable living cells. . The temperature-responsive biodegradable polymer composition of the present invention can be in a solid state and can be dissolved in a medium containing water in a short time. Therefore, it is excellent in operability and handleability, and can be dissolved immediately when necessary.

  The temperature-responsive biodegradable polymer composition of the present invention (hereinafter also simply referred to as a polymer composition) includes the triblock copolymer (1) (hereinafter also simply referred to as a triblock copolymer), and There is no particular limitation as long as it contains (2) sucrose and / or lactose. For example, (i) a triblock copolymer and a polymer composition comprising only sucrose and / or lactose, (ii) a polymer composition further containing a drug in (i), (iii) a triblock copolymer Examples thereof include a polymer composition containing coalescence, water, and sucrose and / or lactose, (iv) a polymer composition further containing a drug in (iii) above, and the like. In the following description, unless otherwise specified, the polymer composition of the present invention is described as a solid composition, but the polymer composition of the present invention is not limited to a solid. That is, the polymer composition of the present invention includes both liquid and solid forms. The solid polymer composition of the present invention can be obtained, for example, by drying a liquid polymer composition of the present invention dissolved in a solvent. The liquid polymer composition of the present invention can be obtained, for example, by dissolving the triblock copolymer (1) and the sucrose and / or lactose (2) in a medium containing water. It can also be obtained by dissolving the solid polymer composition of the present invention in a medium containing water.

(1) Triblock copolymer The polymer composition of the present invention contains an ABA type or BAB type triblock copolymer. The triblock copolymer is biodegradable, and the A block includes poly (lactic acid-co-glycolic acid) (PLGA), and the B block includes polyethylene glycol (PEG).

Physical properties of triblock copolymer; for example, mass ratio of PLGA segment (A segment) and PEG segment (B segment) to triblock copolymer; weight average molecular weight of PLGA segment and PEG segment; Each physical property such as the number average molecular weight (Mn) and the ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn); the molar ratio of lactic acid and glycolic acid in PLGA; the degree of polymerization of lactic acid and glycolic acid; There is no particular limitation. When a preferable example of each of the above physical properties is given, in the case of an ABA type triblock copolymer,
The mass ratio of the PLGA segment and the PEG segment is preferably such that the PLGA segment constitutes 30 to 75% by mass of the triblock copolymer, and the PEG segment constitutes 25 to 70% by mass of the triblock copolymer,
The weight average molecular weight of the PLGA segment is preferably 1.0 k to 2.0 k (1000 to 2000),
The weight average molecular weight of the PEG segment is preferably 1.0 k to 1.5 k (1000 to 1500),
The number average molecular weight (Mn) of the triblock copolymer is preferably 3.0 k to 5.5 k (3000 to 5500),
The ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight of the triblock copolymer is preferably 1.0 to 1.8,
The molar ratio of lactic acid to glycolic acid in PLGA is preferably lactic acid (LA): glycolic acid (GA) = 0.3: 1 to 5.0: 1 (molar ratio),
The degree of polymerization of lactic acid is preferably 3 to 10,
The polymerization degree of glycolic acid is preferably 2-9.

In the case of a B-A-B type triblock copolymer,
The mass ratio of the PLGA segment and the PEG segment is preferably such that the PLGA segment constitutes 30 to 75% by mass of the triblock copolymer, and the PEG segment constitutes 25 to 70% by mass of the triblock copolymer,
The weight average molecular weight of the PLGA segment is preferably 2.0 k to 3.0 k (2000 to 3000),
The weight average molecular weight of the PEG segment is preferably 0.5k to 1.0k (500 to 1000),
The number average molecular weight (Mn) of the triblock copolymer is preferably 3.0k to 5.0k (3000 to 5000),
The ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight of the triblock copolymer is preferably 1.0 to 1.8,
The molar ratio of lactic acid to glycolic acid in PLGA is preferably lactic acid (LA): glycolic acid (GA) = 0.5: 1 to 5.0: 1 (molar ratio),
The degree of polymerization of lactic acid is preferably 2-7,
The polymerization degree of glycolic acid is preferably 1.5 to 5.

Each of the above molar ratio, the degree of polymerization and mass ratios, for example ¹ H-NMR or the like known method can be measured using the respective number average molecular weight above and a weight average molecular weight, for example, above ¹ H-NMR In addition, it can be measured using GPC (gel filtration chromatography) or the like.

  When the triblock copolymer is ABA type, the following formula (A):

And is also referred to as PLGA-b-PEG-b-PLGA (b means block). In the above formula (A), x, y and z are values that can satisfy the above-mentioned physical properties, for example, x is preferably a number of 20 to 40, more preferably a number of 22 to 35. . y is the same or different and is preferably a number of 3 to 10, more preferably a number of 3 to 8. z is the same or different and is preferably a number of 2 to 9, more preferably a number of 3 to 6. In addition, x, y, and z represent the average number of each unit in a polymer, and are calculated | required from < ¹ > H-NMR and GPC. In the PLGA segment indicated by [] in the formula (A), the arrangement of the lactic acid unit and the glycolic acid unit is not regular and is not limited to the order of the arrangement of the formula (A). Y and z represent the average number of each of the lactic acid units and glycolic acid units contained in one PLGA segment.

  Further, when the triblock copolymer is of the B-A-B type, for example, the following formula (B):

[In Formula (B), R is the same or different and is H or CH ₃ , respectively. Or the following formula (C):

[In the formula (C), R is the same or different and each represents H or CH ₃ ;

It is. ]. In the above formula (B) or formula (C), x, y and z are also values that can satisfy the above-mentioned physical properties, respectively, and x is the same or different and each preferably a number of 10 to 25 The number of 11-23 is more preferable. y are the same or different, and each is preferably a number of 5 to 10, more preferably a number of 7 to 10. z is the same or different, and is preferably a number of 5 to 10, more preferably a number of 5 to 8. p is preferably a number of 2 to 6, q is preferably a number of 1 to 6, and r is preferably a number of 1 to 6. In addition, x, y, and z represent the average number of each unit in a polymer, and are calculated | required from < ¹ > H-NMR and GPC. In the PLGA segment represented by [] in the formula (B) or the formula (C), the arrangement of the lactic acid unit and the glycolic acid unit is not regular, and in the order of the arrangement of the formula (B) or the formula (C). It is not limited. Y and z represent the average number of each of the lactic acid units and glycolic acid units contained in one PLGA segment.

  Triblock copolymers have a gel transition temperature between room temperature and body temperature. Specifically, when the triblock copolymer is dissolved in a medium containing water such as water or phosphate buffered saline (PBS), it is in a sol state near room temperature, and in a gel state when heated to near body temperature. To change. Note that PLGA-b-PEG-b-PLGA is a viscous liquid at room temperature and without solvent.

  The sol-gel transition temperature of the polymer composition of the present invention, the mechanical strength in the gel state, the molecular weight of the PEG segment and the PLGA segment in the copolymer, the content of sucrose and / or lactose described later, triblock It can be adjusted by adjusting the concentration and the like of the copolymer.

  The triblock copolymer can be produced, for example, by the following method.

(2) Sucrose and / or lactose The polymer composition of the present invention contains sucrose and / or lactose together with a triblock copolymer. As a result, a polymer composition that can be in a solid state while maintaining a sol-gel transition property that responds to temperature, and that can be dissolved in a short time when dissolved in a medium containing water. Is obtained. The reason why the above effect is achieved is that the triblock copolymer, which is a solid and water-soluble sucrose and / or lactose liquid, adsorbs at the molecular level, and (i) It is presumed to have both the property of sol-gel transition responding to the temperature caused by coalescence and the property of (ii) maintaining the water solubility and solid state caused by sucrose and / or lactose. Each of the sucrose and / or lactose may be used alone, or two may be used in combination. When two types are used in combination, the ratio of sucrose and lactose is not particularly limited, but sucrose: lactose = 99.9: 0.1 to 0.1: 99.9 (mass ratio) is preferable.

  Although content of sucrose and / or lactose is not specifically limited, 25-100 mass parts is preferable with respect to 100 mass parts of triblock copolymers, and 25-50 mass parts is more preferable. When the content of sucrose and / or lactose is within the above range, the sucrose and / or lactose can be dissolved in a medium containing water in a shorter time, and the uniformity and fluidity after re-dissolution are excellent.

  In the polymer composition of the present invention, the concentration of the polymer composition exhibiting temperature-responsive behavior is usually about 5 to 30% by mass, preferably about 10 to 25% by mass for the triblock copolymer. The polymer composition of the present invention can be diluted in a medium containing water, such as water, physiological saline, phosphate buffered saline (PBS), or phosphate buffer (without salt). . In the present specification, those diluted with a medium containing water are also included as the polymer composition of the present invention.

  When the liquid polymer composition of the present invention was prepared so that the triblock copolymer was 10% by mass, and immersed in a phosphate buffer solution at pH = 7.4 at 37 ° C. above the gelation temperature, The decrease rate of the molecular weight after 13 days is preferably 70 to 80%.

  The polymer composition of the present invention can be solidified (powdered) by drying. What is necessary is just to perform the drying method according to the following methods. The solid polymer composition of the present invention is excellent in storage stability and can be redissolved in a short time in a medium containing water.

≪2. Method for producing temperature-responsive biodegradable polymer composition >>
The method for producing the temperature-responsive degradable polymer composition of the present invention is not particularly limited, but for example, the following (i) and (ii):
(i) Step 1 for producing the above triblock copolymer by polymerizing lactide and glycolide in the presence of polyethylene glycol, methoxy-polyethylene glycol or aliphatic diol, and
(ii) Step 2 of dissolving the (1) triblock copolymer and the (2) sucrose and / or lactose in a solvent,
In order. According to the production method, a temperature-responsive biodegradable polymer composition containing the above-described triblock copolymer and sucrose and / or lactose can be suitably produced.

Process 1
In step 1 of the production method of the present invention, the triblock copolymer is obtained by polymerizing lactide and glycolide in the presence of PEG, MeO-PEG (also referred to as methoxy-polyethylene glycol or polyethylene glycol monomethyl ether) or aliphatic diol. Manufacturing. Lactide can be used singly or in combination of two or more of L, L form (L-lactide), D, D form (D-lactide), D, L form (meso-lactide).

An example is shown regarding the polymerization method. The triblock copolymer of the above formula (A) can be produced by polymerizing lactide and glycolide using PEG as a polymer initiator in the presence of Sn (Oct) ₂ (tin octylate). In addition, the triblock copolymer of the above formula (B) polymerizes lactide and glycolide using an aliphatic diol as an initiator, and further binds PEG and / or MeO-PEG to the ends of the obtained symmetrical polymer. By doing so, it can be manufactured. Further, the triblock copolymer of the above formula (C) is prepared by synthesizing an AB diblock copolymer by polymerizing lactide and glycolide using MeO-PEG, and then diisocyanate compound, dicarboxylic acid compound and the like. It can be produced by using and bonding the AB diblock copolymers together by a condensation reaction.

  Examples of the aliphatic diol include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, and 1,4-butanediol.

The amount of each raw material of lactide, glycolide, PEG, MeO-PEG, and aliphatic diol used is not particularly limited, and may be appropriately adjusted so as to satisfy, for example, preferable physical properties of the above-described triblock copolymer. In addition, dried lactide, glycolide, PEG, MeO-PEG, aliphatic diol and Sn (Oct) ₂ may be used.

  After completion of the polymerization, the triblock copolymer can be reprecipitated using a good solvent and a poor solvent. As the good solvent, for example, chloroform can be used, and as the poor solvent, for example, diethyl ether can be used.

Process 2
In step 2 in the production method of the present invention, (1) the triblock copolymer and (2) sucrose and / or lactose are dissolved in a solvent. Thereby, the liquid polymer composition of the present invention in which the triblock copolymer and sucrose and / or lactose are uniformly dissolved in the solvent is obtained.

  The solvent is not particularly limited as long as it can dissolve the triblock copolymer and sucrose and / or lactose, and examples thereof include a medium containing water and acetone. In particular, a medium containing water is preferable. As the medium containing water, the above-mentioned medium containing water (that is, water, physiological saline, phosphate buffered saline, phosphate buffer without sodium chloride, etc.) can be used. It is preferable to use the solvent so that the triblock copolymer is about 15 to 25% by mass.

Process 3
In the production method of the present invention, in step 3 after step 2, the liquid polymer composition of the present invention may be dried to bring the polymer composition into a solid state.

  The drying method is not particularly limited. For example, vacuum freeze drying, hot air drying, vacuum reduced pressure drying, infrared heat drying, microwave heat drying and the like can be mentioned. Of these, vacuum freeze-drying is preferred. When vacuum freeze drying is performed on the liquid polymer composition of the present invention, a solution containing a triblock copolymer and sucrose and / or lactose is frozen, and then the frozen solution is dried under vacuum pressure. By substituting, the frozen solvent is sublimated. The solid polymer composition of the present invention obtained by the vacuum freeze-drying has a large number of gaps and a large surface area. Therefore, the polymer composition is excellent in storage stability and easily re-dissolved in a shorter time in the medium containing water.

  Each condition of vacuum freeze-drying is not limited. For example, after freezing at a temperature that allows freezing (below −0 ° C.) and then drying at room temperature (eg, 10-20 ° C.) for 24 hours under a pressure of about 5-20 Pa, A molecular composition is obtained.

  In order to obtain the solid polymer composition of the present invention, the above-described drying is performed on the liquid polymer composition of the present invention in which the triblock copolymer is about 1 to 5% by mass. Is preferred.

≪3. Properties and applications of temperature-responsive biodegradable polymer composition >>
As described above, the polymer composition of the present invention has good biocompatibility, biodegradability and temperature responsiveness.

  Here, the temperature-responsive sol-gel transition generally indicates a transition from a sol (solution) state to a gel (solid) state with a solution of a compound (or polymer composition) as a boundary at a gelation temperature. Refers to nature. Specifically, it refers to the property that when an aqueous solution of a compound (or polymer composition) is heated to a temperature equal to or higher than the gelation temperature, it becomes a gel state, and when cooled to a temperature lower than that, it dissolves again and returns to a transparent sol state. .

  The aqueous solution of the polymer composition of the present invention has a gelation temperature in the range of about 10 to 50 ° C., and the gelation temperature can be easily adjusted in such a range, and its application range is extremely wide. In particular, it can be mixed with a drug and used as a medical material.

  For example, in an aqueous solution of a polymer composition having a gelation temperature in the range of 25 to 35 ° C, the gelation temperature must exist between room temperature (eg, about 10 to 20 ° C) and body temperature (about 35 to 37 ° C). Thus, it can be administered into the body by injection in a solution (sol) state, and a hydrogel can be formed in the body. When such a polymer composition is mixed with a drug, it is in a solution state near room temperature and is easy to handle at the time of injection. On the other hand, it becomes an insoluble gel state near body temperature, so that it becomes insoluble after administration in the body. Early diffusion of the drug can be suppressed, and the retention of the drug at the administration site can be improved. Therefore, it can be suitably used as a biodegradable polymer material in an injectable preparation, particularly a long-lasting injectable preparation.

  Examples of the administration form include subcutaneous injection and intramuscular injection.

  The blending amount of the polymer composition in the pharmaceutical composition can be appropriately selected depending on the type of drug used and the like. For example, it may be about 60-99.9% by mass with respect to the total mass of the pharmaceutical composition.

The drug used in the pharmaceutical composition is not particularly limited, but includes physiologically active peptides, proteins, other antibiotics, antitumor agents, antipyretic agents, analgesics, antiphlogistics, antitussive expectorants,
Sedative, muscle relaxant, antiepileptic agent, antiulcer agent, antidepressant agent, antiallergic agent, cardiotonic agent, arrhythmia agent, vasodilator, antihypertensive diuretic agent, antidiabetic agent, anticoagulant, hemostatic agent, anti Tuberculosis agents, hormonal agents, narcotic antagonists and the like.

The amount of the drug in the pharmaceutical composition of the present invention can be appropriately selected depending on the type of drug. In particular, in the case of a sustained injection, the amount of the drug is determined by the type of drug, the period of sustained release, and the like. For example, when the drug is a peptide, in order to obtain a sustained-release preparation of about 1 week to about 1 month, it is usually contained in an amount of about 10% to 50% by mass relative to the total mass of the pharmaceutical composition.

  Moreover, since the polymer composition of the present invention has temperature responsiveness, biodegradability, and safety for living bodies, it can be used as a tissue adhesion preventing material after surgery. Adhesion can be prevented by covering visceral tissue after operation by application or spraying and isolating it from other living tissue for a certain period of time.

  Furthermore, the polymer composition of the present invention can be applied as a scaffold for regenerative medicine, a cell culture substrate and the like. The scaffold can be used as a scaffold by mixing cells, the polymer composition of the present invention, a culture solution, and the like in a sol state at a low temperature and gelling the mixture into a predetermined shape at a high temperature. As a cell culture substrate, a fibrous or porous substrate having a predetermined three-dimensional shape is impregnated with a liquid mixture containing cells, the polymer composition of the present invention and a culture solution, and gelled at a predetermined temperature. It is also possible to retain regenerative cells in the substrate. As the fibrous or porous substrate, a material having high biocompatibility such as collagen and hydroxyapatite can be used, which is particularly effective for regeneration of cartilage tissue or bone tissue. Furthermore, it is possible to provide a system for transplanting cells into damaged tissue (cell delivery).

  The temperature-responsive biodegradable polymer composition of the present invention exhibits a sol-gel transition in response to temperature, can be in a solid state, and is dissolved in a medium containing water in a short time. Can do.

FIG. 1 shows a photograph of the solid polymer composition of Example 1. FIG. 2 shows a photograph of the solid polymer composition of Example 4. FIG. 3 shows (a) a photograph of a liquid polymer composition (25 ° C.) in which the solid polymer composition of Example 1 was dissolved in PBS according to Test Example 2, and (b) the liquid polymer composition. A photograph of a polymer composition (37 ° C.) is shown. FIG. 4 shows (a) a photograph of a liquid polymer composition (25 ° C.) obtained by dissolving the solid polymer composition of Example 4 in PBS according to Test Example 2, and (b) the liquid polymer composition. A photograph of a polymer composition (37 ° C.) is shown. FIG. 5 shows a photograph of a liquid polymer composition (25 ° C.) in which the solid polymer composition of Comparative Example 1 was dissolved in PBS according to Test Example 2.

  The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples.

[Production Example 1]
Synthesis of triblock copolymer
PEG (Mw = 1,540) (Polyethylene glycol (1,540), manufactured by Wako Pure Chemical Industries, Ltd.) 5,000 mg (3.3 mmol), D, L-lactide (produced by Musashino Chemical Laboratory, D, L-Lactide) Charge 8,750 mg (63.0 mmol), glycolide (polysciences, Inc.) 3,125 mg (27.0 mmol) and Sn (Oct) ₂ (Wako Pure Chemical Industries, Ltd.) 40 mg (90.0 μmol) in a 140 ° C oil bath Polymerization was carried out for 6 hours. Next, the product was reprecipitated using chloroform as a good solvent and diethyl ether as a poor solvent. Thereby, PLGA-b-PEG-b-PLGA was obtained. The physical properties of the triblock copolymer are as shown in Table 1 below.

[Example 1]
Production of temperature-responsive biodegradable polymer composition 100 mg of the triblock copolymer obtained in Production Example 1 and 25 mg of sucrose were weighed and placed in a sample tube. Next, 1.875 ml of ultrapure water was added to the sample tube and stirred for 7 hours. As a result, a liquid temperature-responsive biodegradable polymer composition of Example 1 (triblock copolymer concentration: 5 wt%) was obtained.

  Subsequently, the polymer composition was vacuum lyophilized. Specifically, after freezing the polymer composition with liquid nitrogen, it is dried at a pressure of about 5 to 20 Pa and at room temperature (20 ° C.) for 24 hours to obtain the solid temperature of Example 1. A responsive biodegradable polymer composition was obtained.

[Examples 2-8 and Comparative Examples 1-5]
Each liquid polymer composition (triblock copolymer concentration: 5 wt%) and the same as in Example 1 except that the kind of additive, the content of the additive, etc. are appropriately changed as shown in Table 2 A solid polymer composition was obtained. Α-CD in Comparative Examples 1 to 3 means α-cyclodextrin. Details of each additive used are shown below.
・ Sucrose: Sucrose (Saccharose), manufactured by Wako Pure Chemical Industries, Ltd. ・ Lactose: Lactose hydrate (lactose), manufactured by Wako Pure Chemical Industries, Ltd. ・ α-CD: α-cyclodextrin, Tokyo Chemical Industry Co., Ltd.・ MeO-PEG (350): Polyethylene glycol (350) monomethyl ether, manufactured by Wako Pure Chemical Industries, Ltd. ・ MeO-PEG (550): Polyethylene glycol (550) monomethyl ether, manufactured by Sigma Aldrich

[Example 7]
A liquid temperature-responsive biodegradable polymer composition (triblock copolymer concentration: 1 wt%) was obtained in the same manner as in Example 1 except that 9.875 ml was used instead of 1.875 ml of ultrapure water. It was. Further, a solid temperature-responsive biodegradable polymer composition was obtained in the same manner as in Example 1.

[Example 8]
A liquid temperature-responsive biodegradable polymer composition (triblock co-polymer) was prepared in the same manner as in Example 1 except that 50 mg was used instead of 25 mg, and 9.85 ml was used instead of 1.875 ml of ultrapure water. Polymer concentration: 1 wt%) was obtained. Further, a solid temperature-responsive biodegradable polymer composition was obtained in the same manner as in Example 1.

[Test Example 1]
Resolubility test PBS (pH = 7.4) so that the concentration of the triblock copolymer (polymer) is 20 wt% for each solid polymer composition of Examples 1 to 8 and Comparative Examples 1 to 5 And then stirred with a magnetic stirrer at room temperature. Thereby, it was visually observed whether or not each of the solid polymer compositions was dissolved in the PBS. Further, when each of the solid polymer compositions was dissolved in the PBS, (i) the time required for the dissolution was measured, and (ii) the dissolution uniformity and fluidity were evaluated. Regarding (ii), the uniformity of dissolution was evaluated visually, and the fluidity was evaluated based on whether or not the polymer composition dissolved in the PBS could pass through a syringe (inner diameter: 0.9 mm). A sample that was uniformly dissolved and had fluidity was evaluated as ◯, and a sample that was not uniformly dissolved and had no fluidity was evaluated as ×. The test results are shown in Table 2 below.

[Test Example 2]
Temperature responsive behavior test For each solid polymer composition of Examples 1-8 and Comparative Examples 1-5, a PBS solution having a triblock copolymer concentration of 20 wt% was prepared in the same manner as in Test Example 1. Prepared. The solution was examined for the presence or absence of sol-gel transition by a test tube gradient method. Specifically, after each of the solutions stored in the sample tube (about 1 cm in diameter) was brought to 37 ° C., the sample tube was inverted. And the thing which did not flow for 30 seconds was considered as the gel. Those that gelled at 37 ° C. were evaluated as ○, and those that did not gel at 37 ° C. were evaluated as ×. The test results are shown in Table 2 below.

Claims (4)

Below (1) and (2):
(1) A-B-A type or B-A-B type triblock copolymer,
The A segment comprises poly (lactic acid-co-glycolic acid);
The B segment comprises polyethylene glycol;
The triblock copolymer, and
(2) contains sucrose and / or lactose ,
The content of the (2) sucrose and / or lactose is 50 to 100 parts by mass with respect to 100 parts by mass of the (1) triblock copolymer , vacuum lyophilization, A temperature-responsive biodegradable polymer composition. The A segment constitutes 30 to 75% by mass of the (1) triblock copolymer,
The vacuum freeze-drying temperature-responsive biodegradable polymer composition according to claim 1, wherein the B segment constitutes 25 to 70% by mass of the (1) triblock copolymer. Below (1) and (2):
(1) A-B-A type or B-A-B type triblock copolymer,
The A block comprises poly (lactic acid-co-glycolic acid);
The B block comprises polyethylene glycol,
The triblock copolymer, and
(2) contains sucrose and / or lactose ,
The method for producing a temperature-responsive biodegradable polymer composition , wherein the content of (2) sucrose and / or lactose is 50 to 100 parts by mass with respect to 100 parts by mass of the (1) triblock copolymer Where (i) and (ii) below:
(i) Step 1 for producing the above triblock copolymer by polymerizing lactide and glycolide in the presence of polyethylene glycol, methoxy-polyethylene glycol or aliphatic diol, and
(ii) Step 2 of dissolving the (1) triblock copolymer and the (2) sucrose and / or lactose in a solvent,
In order, The manufacturing method of the temperature-responsive biodegradable polymer composition characterized by the above-mentioned. Step 3 of bringing the polymer composition into a solid state by vacuum freeze- drying the temperature-responsive biodegradable polymer composition obtained in Step 2;
The manufacturing method of the temperature-responsive biodegradable polymer composition of Claim 3 containing this.

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