WO2006028244A1

WO2006028244A1 - Bioabsorbable porous object

Info

Publication number: WO2006028244A1
Application number: PCT/JP2005/016698
Authority: WO
Inventors: Eiichi Kitazono; Takanori Miyoshi; Hiroaki Kaneko; Chiaki Fukutomi
Original assignee: Teijin Limited
Priority date: 2004-09-07
Filing date: 2005-09-06
Publication date: 2006-03-16
Also published as: TW200612877A; JPWO2006028244A1; JP4481994B2

Abstract

A porous object characterized in that it comprises a fibrous structure made of a bioabsorbable polymer and that the fibrous structure has an average fiber diameter of 0.05-10 µm, an average apparent density of 10-350 kg/m3, and a height of 0.5 mm or higher. It is suitable for use as a bioabsorbable porous object, especially as a prosthetic material or a substrate for cell incubation in the field of regenerative medicine.

Description

Bioabsorbable porous material Technical Field

The present invention relates to a porous body comprising a fiber structure of a bioabsorbable polymer.

Background art

Light

In recent years, as a treatment for severely damaged or lost biological tissue and β, research on regenerative medicine that reconstructs the original biological tissue and organs using the differentiation and proliferation ability of cells is active

It ’s coming. When cells proliferate and grow in vivo, the extracellular matrix functions as a scaffold and constructs the tissue.If the tissue is severely damaged and defective, the cell itself produces the matrix. Need to be supplemented with artificial and natural materials. In other words, prosthetic materials (scaffolding materials) are an important factor that gives an optimal environment for tissue construction. The properties required for this scaffold material include: 1) bioabsorbability, 2) cell adhesion, 3) porosity, 4) mechanical strength, etc., and create materials that satisfy these properties. Synthetic polymers (polyglycolic acid, polylactic acid, poly force prolagtone, etc.) (eg Υ. Ikada, H. Tsuj i,

Macromol. Rapid. Commun., 21, 117 (2000), J. Mayer, E. Karamuk, T. Akaike, E. W intermantal, J. Control. Release., 4, 81 (2000)) _s natural polymer ( Collagen, gelatin, elastin, hyaluronic acid, alginic acid, chitosan, etc.

Weinberg. C. B, Bell. E, Science., 231, 397 (1986),

Aigner. J, Tegeler. J. A, Hutzler. P, Carapoccia. D, Naumann. A,.

J. Biomed. Mater. Res., 42, 172 (1998) _N inorganic materials (hydroxyapatite, β · -tricalcium phosphate) (eg

Laffargue. P. H, Marchandise. X, Bone., 25 (2S), 55S (1999)), and their complexes have been studied.

As mentioned above, there are many important properties required for prosthetic materials (scaffolding materials). It is porous. This is important in terms of providing sufficient oxygen and nutrients to the cells needed to regenerate the tissue and expelling carbon dioxide and waste products quickly. Therefore, lyophilization methods (for example, to achieve the porosity of the scaffold material)

K. Wang, K. E. Healy, Polymer., 36, 837 (1995)), phase separation (eg

P. X. Ma, R. Zhang, J. Biomed. Mater. Res., 45, 285 (1999)), foaming methods (eg

D. J. Mooney, R. Langer, Biomaterials., 17, 1417 (1996)).

In the freeze-drying method or the phase separation method, the pores of the obtained structure have a scaly shape, which makes it difficult for cells to invade and has an unsatisfactory problem as a scaffold material. Another problem with the foaming method is that it is difficult for cells to enter because there is a single pore.

Further, WO 2 0 4/8 8 0 24 discloses an aggregate of fibers made of a thermoplastic polymer having an average fiber diameter of 0.1 to 20 μm, and any fiber of the fibers. A nonwoven fabric having an irregular cross-sectional surface and an average apparent density of 10 to 95 kg Zm ³ is described. However, a scaffold material having further thickness and strength is required.

Moreover, the actual living tissue shows a continuous gradient structure rather than a uniform structure. For example, in articular cartilage tissue, the cell density of the surface layer is low, but the closer to the lower bone, the higher the cell density. In other words, in order to regenerate a tissue closer to a living body, it is important to develop a scaffold material exhibiting a continuous gradient structure. However, in the prior art, it is difficult to control the spatial distribution of pores, and there is a limit to the production of a scaffold material showing a continuous gradient structure. More recently, however, Athanasiou et al. (Eg US Pat. No. 5,607,474), Mikos et al. (Eg US Pat. No. 5,514,378), ETHIC0N

INCORPORATED (eg US Pat. No. 6,306,424) et al. Reported a study of scaffold materials that exhibit a continuous gradient structure. However, even if the structure is dissimilar to that of a living body, or even if it shows a gradient structure, the production method is lyophilization or heat drying using incompatibility between the polymer and the solvent. The pores have a scaly shape, which makes it difficult for cells to enter and is not suitable as a scaffold material. Disclosure of the invention

The purpose of this effort is to provide a bioabsorbable porous body, particularly a porous body suitable for a cell culture substrate in the field of regenerative medicine. Specifically, it is to provide a bioabsorbable porous body composed of a fiber structure of a bioabsorbable polymer, and the bioabsorbable porous body by a simple method.

That is, the present invention is as follows.

1. It consists of a fiber structure of a bioabsorbable polymer, the fiber structure has an average fiber diameter of 0.05 to 10 μ.πι, an average apparent density of 10 to 35 O kg / m ³ , and a height. Is a porous body characterized by being 0.5 or more.

2. The porous body according to 1, wherein the porous body has an average fiber diameter of 0.2 to 8 ^ um.

3. The porous material according to 1, wherein the average apparent density is 100 to 25 O kg / m ³ .

4. The porous material according to 3, wherein the porous material has a gradient structure in which the porosity is 10 to 90% and different porosity is continuously present.

5. The porous body according to 1, further comprising 0 · 01 to 50 parts by weight of a dispersion aid with respect to 100 parts by weight of the bioabsorbable polymer.

6. The porous body according to 5, wherein the dispersion aid exhibits bioabsorbability.

7. The dispersion aid is at least one selected from the group consisting of phospholipids, carbohydrates, glycolipids, steroids, polyamino acids, protein koji, and polyoxyalkylenes. 7. The porous body according to 6,

8. The porous body according to 1, wherein the bioabsorbable polymer mainly comprises an aliphatic polyester.

9. The porous body according to 8, wherein the aliphatic polyester is at least one selected from the group consisting of polydalicolic acid, polylactic acid, polyprolacton, and copolymers thereof. '

A prosthetic material comprising the porous material according to 10.1. 1 1. A step of spinning a solution comprising a volatile solvent and a bioabsorbable polymer by an electrostatic spinning method to obtain a fiber structure, a step of cutting the obtained fiber structure, and the cut fiber structure as a solvent Including a step of suspending and centrifuging in, followed by a step of freeze-drying. The fiber structure of the bioabsorbable polymer has an average fiber diameter of 0 · 05 to 10 μm, and an average apparent density. Is a porous body having a thickness of 0.5 to 5 thighs. .

1 2. The production method according to 1 1, wherein spinning is performed using a solution further containing a dispersion aid.

1 3: A bioabsorbable polymer characterized by using a static eliminator between a nozzle and a collecting electrode in a method of spinning a solution comprising a volatile solvent and a bioabsorbable polymer by an electrostatic spinning method. A porous structure having an average fiber diameter of 0.05 to 10 m, an average apparent density of 10 to 35 kg / m3, and a thickness of 0.5 mm or more. Body manufacturing method. The invention's effect ,

The bioabsorbable porous material of the present invention is useful as a prosthetic material. According to the present invention, a molded body having a desired shape can be provided, and it is useful as a prosthetic material in a portion where a high load such as a cartilage damaged portion is applied. '

The bioabsorbable porous material of the present invention is useful as a cell culture substrate in the field of regenerative medicine, particularly as a substrate for cartilage regeneration, among prosthetic materials. ,

When a porous body is used for transplantation, mechanical strength that can withstand weighted compression in the initial stage of transplantation is required. However, according to the present invention, a porous body having mechanical strength according to the application can be provided. Brief Description of Drawings

FIG. 1 shows an example of an apparatus used in an electrostatic spinning method for discharging a spinning solution into an electrostatic field in the production method of the present invention. FIG. 2 shows an example of an apparatus used in the electrospinning method in which fine droplets of a spinning solution are introduced into an electrostatic field in the production method of the present invention.

FIG. 3 shows an example of an apparatus used in the electrospinning method of production method 2 of the present invention.

Fig. ⁴ Photomicrograph of the porous material obtained in Example ³

Fig. 5 Optical micrograph of the porous material obtained in Example 4

Fig. 6 Scanning electron micrograph of the upper part of the porous body obtained in Example 5

Fig. 7 Scanning electron micrograph of the middle part of the porous body obtained in Example 5

Fig. 8 Scanning electron micrograph of the lower part of the porous body obtained in Example 5

Figure 9 Optical micrograph of the porous material obtained in Example 6

Fig. 10 Optical micrograph of the porous material obtained in Example 7 'Fig. 1 Microscopic photo of the porous body in the vicinity of the 8th week after surgery in Example 8 Fig. 1 2. 8 weeks after surgery in Example 9 Fig. 1 3 Photomicrograph of the vicinity of the defect at 8 weeks after the operation of Comparative Example 1.

Figure 1 4 Items and scores used in histological evaluation

Figure 1 5 Histological evaluation

1 Nozzle.

2 Spinning fluid

3. Spinning fluid holding tank

4, Λ pole

5. Fibrous material collection electrode

6. 问 ^ jJt ^ Bit-e?

7. Nozzle

8 Spinning fluid

9. Spinning fluid holding tank

1 0. Electrode

1 1. Fibrous material collection electrode 1 2. High voltage generator

1 3. Nozzle

1 4. Spinning fluid

1 5. Spinning fluid holding tank

1 6. Electrode

1 7.

1 8. High voltage generator

1 9. Winding device

2 0. Electrostatic eliminator Preferred embodiment of the invention

Hereinafter, the present invention will be described in detail. These descriptions are merely examples of the present invention and do not limit the scope of the present invention. It goes without saying that other embodiments may belong to the category of the present invention as long as they match the gist of the present invention.

The fiber structure used in the present invention is a three-dimensional structure formed by laminating and accumulating single or plural fibers. The average fiber diameter of the fiber structure is 0.05 to 10 μπι. If the average fiber diameter is smaller than 0.05 μπι, the strength of the fiber structure cannot be maintained, which is not preferable. On the other hand, if the average fiber diameter is larger than 10 μm, the specific surface area of the fiber is small and the number of engrafted cells is reduced, which is not preferable. More preferably, the average fiber diameter is 0.2 to 10 μπιι, more preferably the average fiber diameter is 0.2 to 8 m.

Further, the arbitrary cross section of the fiber may be a substantially perfect circle or an irregular shape. If the cross section of an arbitrary fiber is irregular, the specific area of the fiber increases, so that a sufficient area for the cell to adhere to the fiber surface can be taken during cell culture.

Here, the arbitrary cross section of the fiber is irregular, which means any shape in which the cross section of the fiber does not take a substantially circular shape, and the fiber surface has uniform recesses and / or protrusions. And the case where it is roughened.

The irregular shape includes fine concave portions on the fiber surface, fine convex portions on the fiber surface, It may be due to at least one selected from the group consisting of concave portions formed in a streak shape in the fiber axis direction, convex portions formed in a streak shape in the fiber axis direction on the fiber surface, and fine pores on the fiber surface. Preferably, these may be formed singly or a plurality thereof may be mixed. · Here, the above-mentioned “fine concave portions” and “fine convex portions” mean that the concave or convex portions of 0.1 to 1 μηι are formed on the fiber surface, and “fine pores”. The term “pores” having a diameter of 0.1 to 1 μηι is present on the fiber surface. In addition, the above-described concave and ridges or protrusions formed in a streak shape means that a ridge shape having a width of 0.1 to 1 μm is formed in the fiber axis direction.

The porous body made of the fiber structure of the present invention has an average apparent density: I 0 to 35 O kg / m ³ . If the average apparent density is lower than 1 O kg / m ³ , the cell penetration is good, but the mechanical strength is low, and if it is higher than 35 O kg / m ³ , it is difficult for cells to enter, which is not preferable as a scaffold material. . The average sheep density can be calculated by measuring the volume (area X thickness) and mass of the obtained porous material. The average apparent density is preferably 50 to ³ OO kg / πχ ³ . More preferably, it is 100-25 O kg / m < ³ >. .

The porous body composed of the fiber structure of the present invention preferably has a porosity of 10 to 90%. If the porosity is lower than 10%, the number of cells to be engrafted is small. If the porosity is higher than 90%, the number of cells to be engrafted is large, but most of them are spaces, so the mechanical strength is low and it is not preferable as a scaffold material. There is a case. Furthermore, the porosity is preferably 20 to 70%, more preferably 2050%. The porosity can be calculated from the average apparent density and the inherent polymer density.

The porous body comprising the fiber structure of the present invention may be either uniform in average apparent density and / or porosity or may have a gradient, and can be selected according to the required scaffold site.

The gradient structure in which different porosities exist continuously may be a gradient structure having two or more stages, and may be two or more stages. Even with such a gradient structure, the average apparent density of the entire porous body is 10 to 35 O kg / m ³ . In this case, the porosity is 10 to 90%.

The porous body of the present invention is a three-dimensional shape such as a cylinder, a polygonal column, a truncated cone, a truncated cone, The height is 0.5 thigh or more, and it can be said that it depends on the site used as the cell culture substrate regardless of the upper limit of the height. If the height is less than 0.5 mm, the mechanical strength is low, and it is not preferable as a cell culture substrate for tissues with high loads such as knee joints.

The porous body of the present invention can be used for, for example, piercing and embedding in a damaged part of a living body, and regenerating cells on the surface of a binding material, but the porous body of the present invention is adapted to a desired shape. It has the characteristic that a molded object can be provided. Since a substrate with the required thickness can be provided, it is superior in shape stability without interfacial delamination compared to, for example, a laminate in which non-woven fabrics are stacked and pressure-bonded. Useful as a binding material, 'cell culture substrate.

For example, when a porous body is used for transplantation, mechanical strength that can withstand weighted compression in the initial stage of transplantation is required. However, according to the present invention, a porous body having mechanical strength according to the application can be provided.

The bioabsorbable polymer constituting the porous body of the present invention is preferably mainly composed of an aliphatic polyester. Examples of the aliphatic polyester include polydaricholic acid, polylactic acid, polystrength prolatatone, polydioxanone, trimethylene carbonate, polybutylene succinate, polyethylene succinate, and copolymers thereof. Of these, the aliphatic polyester is preferably at least one selected from the group consisting of polyglycolic acid, polylactic acid, polystrength prolactone, and copolymers thereof.

The porous body of the present invention preferably further contains a dispersion aid. More preferably, the dispersion aid exhibits bioabsorbability. The dispersion aid is preferably at least one selected from the group consisting of phospholipids, carbohydrates, glycolipids, steroids, polyamino acids, proteins, and polyoxyalkylenes. Les. Specific dispersing agents include phospholipids such as phosphatidinorecholine, phosphatidylethanolanolamine, phosphatidylserine, phosphatidinoregliceronorole and Z or polygalacturonic acid, heparin, chondroitin sulfate, Hyanorelon acid, dermatan sulfate, chondroitin, dextran sulfate, sulfated cellulose, alginic acid, dextran, canoleboxymethyl chitin, galactmann Naan, gum arabic, tragacanth gum, dillang gum, sulfated dielan, cara gum, carrageenan, agar, xanthan gum, curdlan, pullulan, cellulose, starch, canolepoxymethinoresenorelose, methinoresenorelose, gnolecomannan, chitin, Carbohydrates such as chitosan, xyloglucan, lentinan Z or galactocerebroside, glucocerebroside, globoside, ratatosinoreseramide, trihexosylceramide, paragloboside, galactosyldiacylglycose mouthpiece, sulfoquino Glycolipids such as bosyl diacylglycerol, phosphatidylinositol, glycosyl polyprenol phosphate and / or steroids such as cholesterol, cholic acid, sapogenin, digitoxin And / or polyamino acids such as polyasparagic acid, polyglutamic acid, polylysine and proteins such as Z or collagen, gelatin, fibronectin, fibrin, laminin, casein, keratin, sericin, thrombin and Z or polyoxyethylenealkyl And polyoxyalkylenes such as ether, polyoxyethylene propylene alkyl ether, polyoxyethylene sorbitan ether, and the like.

A preferable content of the dispersion aid in the bioabsorbable porous material is 0.001 to 50 parts by weight with respect to 100 parts by weight of the bioabsorbable polymer. If the content is less than 0.01 part by weight, the wettability with water is poor and it may be difficult to cut the fiber with a homogenizer, and the fiber may be difficult to settle upon centrifugation. If it is longer than 50 parts by weight, fibers are hardly formed at the spinning stage. More preferably, the content is 0.1 to 20 parts by weight. Moreover, cell penetration into the porous material is enhanced by including a dispersion aid. .

The bioabsorbable porous material of the present invention may further contain a third component other than the bioabsorbable polymer and the dispersion aid. These components include, for example, FGF (fibroblast growth factor), EGF (epidermal growth factor), PDG F_ (platelet-derived growth factor), TGF— (type 3 transforming growth factor), NG F (nerve growth factor) ), HGF (hepatocyte growth factor), BMP (bone morphogenetic factor) and other cell growth factors.

The porous body of the present invention is useful as a prosthetic material. In the damaged part of the cartilage It can be used in a method for treating cartilage damage. The treatment method can be performed by the following procedure. First, the joint is operated to expose the cartilage. Next, a hole is made in the damaged part of the cartilage with a drill or the like. It is preferable that the hole is deep enough to reach the subchondral bone below the cartilage tissue with a thickness of about 2 mm. Therefore, the depth of the hole is preferably about 3-8 mm. Thereafter, the prosthetic material of the present invention having a shape substantially coinciding with the inner diameter of the hole is embedded. Thereafter, the surgical site is repaired and cartilage is regenerated by natural healing.

The present invention includes a step of spinning a solution comprising a volatile solvent and a bioabsorbable polymer by an electrostatic spinning method to obtain a fiber structure, a step of cutting the obtained fiber structure, and a cut fiber structure. A step of suspending in a solvent and centrifuging, followed by a step of freeze-drying, comprising a fiber structure of a bioabsorbable polymer, and the average fiber diameter of the fiber structure is 0.05 to 10 μπι, average appearance This is a method for producing a porous body having a density of 10 to 35 O kg / m ³ and a thickness of not less than 5 mm (Method 1). It is preferable to perform spinning using a solution containing a dispersion aid in the solution.

Further, the present invention is characterized in that in a method of spinning a solution comprising a volatile solvent and a bioabsorbable polymer by an electrostatic spinning method, a static eliminator is used between the nozzle and the collecting electrode. It is composed of a fiber structure of a bioabsorbable polymer, and the average fiber diameter of the fiber structure is from 0.05 to 10 μπι, the average apparent density is from 10 to 35 kg / m ³ , and the thickness is 0. This is a method for producing a porous body of 5 mm or more (Method 2).

First, method 1 is described.

The volatile solvent that forms a solution in the present invention is a substance that dissolves a bioabsorbable polymer, has a boiling point of 200 ° C. or less at normal pressure, and is liquid at room temperature. Specific volatile solvents include, for example, methylene chloride, chlorophenol, acetone, methanol, ethanol, propanol, isopropanol, toluene, tetrahydrofuran, 1,1,1,3,3,3 —hexafluoro Examples include roisopropanol, water, 1,4-dioxane, carbon tetrachloride, cyclohexane, cyclohexanone, N, N-dimethylformamide, and acetonitrile. Among these, methylene chloride, black mouth form, and acetone are particularly preferable in view of solubility of bioabsorbable polymers, particularly aliphatic polyesters. These solvents may be used alone or in combination with multiple solvents. You may let them. In the present invention, other solvents may be used in combination as long as the object is not impaired.

The electrospinning method used in the present invention is a method in which a bioabsorbable polymer or a solution in which a bioabsorbable polymer and a dispersion aid are dissolved in a volatile solvent is discharged into an electrostatic field formed between electrodes. This is a method for producing a fibrous material by spinning the yarn toward the electrode. The fibrous material indicates not only the state in which the solvent in the solution has already been distilled off, but also the state in which the solvent is still contained. The electrode used in the present invention may be any metal, inorganic, or organic material as long as it exhibits conductivity. In addition, a thin film of conductive metal, inorganic, or organic material may be provided over the insulator. The electrostatic field in the present invention is formed between a pair or a plurality of electrodes, and a high voltage may be applied to any of the electrodes. This includes, for example, the use of two high-voltage electrodes with different voltage values (for example, 15 kV and 10 kV) and a total of three electrodes connected to ground, or a number exceeding three. This includes the case of using other electrodes.

The concentration of the bioabsorbable polymer in the bioabsorbable polymer solution in the present invention is preferably 1 to 30% by weight. When the concentration of the bioabsorbable polymer is lower than 1% by weight, it is not preferable because the concentration is too low to form a fibrous substance. On the other hand, if it is higher than 30% by weight, the fiber diameter of the obtained fibrous substance becomes large, which is not preferable. A more preferable concentration of the bioabsorbable polymer is 2 to 20% by weight. Any method can be used to discharge the solution into the electrostatic field. For example:-As an example, we will explain below using FIG. By supplying Solution 2 to the nozzle, the solution is placed in an appropriate position in the electrostatic field, and the solution is electrolyzed from the nozzle to fiber. For this purpose, an appropriate device can be used. For example, a syringe-like solution is discharged by applying appropriate means, for example, a high voltage generator 6 to the tip of the cylindrical solution holding tank 3 of the syringe. Install nozzle 1 and guide the solution to its tip. 'The tip of the ejection nozzle 1 is placed at an appropriate distance from the grounded fibrous material collecting electrode 5 and when the solution 2 exits the tip of the ejection nozzle 1, this tip and the fibrous material collecting electrode 5 A fibrous material is formed between them. It is also possible for a person skilled in the art to introduce fine droplets of the solution into the electrostatic field in a manner that is self-evident. An example will be described below with reference to FIG. 'The only requirement is to place the droplet in an electrostatic field and keep it away from the fibrous material collection electrode 11 at a distance where fibrosis can occur. For example, an electrode 10 that directly opposes the fibrous material collecting electrode may be inserted directly into the solution 8 in the solution holding tank 9 having the nozzle 7.

When supplying the solution into the electrostatic field from the nozzle, the production rate of the fibrous material can be increased by using several nozzles. The distance between the electrodes depends on the charge amount, nozzle dimensions, spinning fluid flow rate, spinning fluid concentration, etc., but when it was about 10 kV, a distance of ⁵ to 20 cm was appropriate. The applied electrostatic potential is generally 3 to: 100 kV, preferably 5 to 50 kV, more preferably 5 to 30 kV. 'The desired potential can be created by any appropriate method! /.

The above description is for the case where the electrode also serves as a collector. However, a collector can be provided separately from the electrode by installing an object that can be a collector between the electrodes. Sheets and tubes can be obtained by selecting the shape of the collector. Furthermore, for example, continuous production is possible by installing a belt-like substance between the electrodes and collecting it. In the present invention, while spinning the solution toward the collecting electrode, the solvent evaporates depending on the conditions, and a fibrous material is formed. At normal room temperature, the solvent completely evaporates until it is collected on the collecting electrode, but if the solvent evaporation is insufficient, it may be spun under reduced pressure conditions. The spinning temperature depends on the evaporation behavior of the solvent and the viscosity of the spinning solution, but is usually 0 to 50 ° C.

The method for cutting the fiber of the present invention is not particularly limited, but it is preferable to use a homogenizer, a pulverizer, or a mill. When cutting, the fibrous material may be cut directly or in a frozen state, or the fibrous material may be suspended in a solvent and cut. Also, when cutting in a solvent, it can be cut more efficiently by increasing the affinity between the fibrous material and the solvent. Therefore, the dispersion aid mentioned as the second component at the stage of spinning the fibrous material is used. It is preferable to contain. The dispersion aid is preferably contained in an amount of 0.01 to 50 parts by weight with respect to 100 parts by weight of the bioabsorbable polymer. Centrifugation performed in the present invention is performed by suspending the fibrous material in a solvent. The concentration of the fiber structure in the solvent is usually about 0.001 to 50% by weight, and the solvent is not particularly limited as long as it can be freeze-dried. However, when handling and safety are considered, Mixed water is preferred. In addition, since the average apparent density and porosity of the porous body depend on the centrifugal acceleration and the centrifugation time, the porous body having the desired average apparent density and porosity can be controlled by controlling the centrifugal acceleration and Z or the eccentric time. Can be obtained. Specifically, when the centrifugal acceleration is high and the centrifugal time is long, the average apparent density of the obtained porous body is high and the porosity is low. On the other hand, when the centrifugal acceleration is low and the centrifugation time is short, the average apparent density of the obtained porous body is low and the porosity is high. Preferable conditions for centrifugal acceleration are 10 00 to 6,00 G, and preferable conditions for centrifugation time are 10 to 40 minutes. By controlling the centrifugal acceleration in this way, it is possible to produce a porous body having a multistage gradient structure.

The freeze-drying step is a step of removing the organic solvent under reduced pressure at the ultimate temperature, and is not particularly limited. The freeze-drying process is preferably performed at 10 to 30 Pa. The lyophilization time is preferably 8 to 24 hours. When freezing, a method in which a temperature gradient is provided and the method of gradually freezing is preferred in terms of obtaining a porous material with few defect structures. 'Note that the type of freeze-dried t «is not particularly limited, and commercially available freeze-dried; can be suitably used.

Method 2 is described below.

The spinning process is the same as in Method 1 above, except that a static eliminator 20 is installed between the nozzle 13 and the electrode 17 to perform spinning, and the yarn accumulated between the nozzle and the electrode 17 is removed. It is collected by a scraper 19 and the collected fiber structure is rolled out using a biopsy trepan to obtain a well-shaped porous body. The static eliminator used here is a device that applies ion air to the spun yarn to maintain a uniform ion balance and relaxes the charged state of the yarn before it reaches the electrode, thereby depositing it in the air. By using this apparatus, it is possible to produce a porous body having a height of 0.5 mm or more.

The average apparent density and porosity of the porous material depend on the rotation speed of the scraper. In other words, it is possible to obtain a porous body having a desired average apparent density and porosity by controlling the rotation speed of the scraper. Specifically, when the number of rotations is high, the obtained porous body has a high average power and a low porosity. On the other hand, when the rotational speed is low, the average apparent density of the obtained porous body is low and the porosity is high. As a preferable condition of the rotation speed, 5 to 200 rpm is used.

By controlling the rotation speed of the scraper in this way, it is possible to produce a porous body having a multi-stage gradient structure. Example

Hereinafter, embodiments of the present invention will be described by way of examples, but these do not limit the present invention.

Polylactic acid-polydaricolic acid copolymer used in this example: Poly DL lactic acid / polyglycolic acid (molar ratio = 50/50) copolymer manufactured by Birmingham Polymers, Inc. Intrinsic viscosity: 1. 08 dL / g, 30 ° C, hexafluoroisopropanol, phosphatidylethanolaminediole oil

As for (C0ATSOME), Nippon Oil & Fats Co., Ltd., Shiojimethylene, and Ethanol were manufactured by Wako Pure Chemical Industries, Ltd.

[Example 1]

Polylactic acid-polyglycolic acid copolymer 0.9 g ', phosphatidylethanolaminediol oil 0.1 g, salt-hethylene methylene Zethanol = 7/2 (parts by weight, amount' parts) 9 g at room temperature (25 ° C) A 10% by weight dope solution was prepared by mixing. Using the apparatus shown in FIG. 2, the fibrous material collecting electrode 11 was discharged for 5 minutes. Inside diameter 0. 8 mm of the jet Nozunore 7, voltage 14.K V, the fibrous material 0. 2 g distances obtained _¾ was 10 cm 'to spray nozzle 7 to the fibrous substance collecting electrode It was placed in 50 ml of ION-exchanged water, and cut with a homogenizer (registered trademark POLY TRON PT 210 0) at a rotation speed of 2,0 ° Orm for 5 minutes. Part of the resulting suspension was rotated using a centrifuge (KUBOTA KN—70, turning radius 15 cm). Centrifugation was performed at several 3,000 rpm (1,500 G) for 25 minutes. Then, after freezing treatment at 120 for 2 hours, freeze-drying was performed at 20 Pa for 6 hours to obtain a porous material, and a cylindrical shape having a diameter of 5 mm and a height of 5 mm was cut out. Table 1 shows the fiber diameter, average apparent density, and porosity of the obtained porous material. For fiber diameter, the sample was treated with a spatter coating (P t 1. O nm), S EM (J SM-53 10 type (manufactured by JEOL)), Calo fast voltage: 2. O kV, shooting angle 3 0 Observation was carried out by °). The apparent density and porosity of the porous material were calculated by the following formula. p— 4 mZ π d ~ n

(ε: porosity, ρ: apparent density of porous material, m: mass, d: diameter, h: thickness, pp: polymer, one intrinsic density (50/50 Poly (DL-lactide-co-glycolide: l.34g / ml))

[Example 2]

A porous material was obtained in the same manner as in Example 1 except that centrifugation was performed for 15 minutes. Table 1 shows the fiber diameter, average apparent density, and porosity of the obtained porous material.

[Example 3]

A porous material was obtained in the same manner as in Example 1 except that centrifugation was performed for 20 minutes. Table 1 shows the fiber diameter, average apparent density, and porosity of the obtained porous material. Fig. 4 shows an optical micrograph of the porous material obtained in Example 3 (D.I GITAL MICROSC OPEE, KEYENCE, magnification: 450 times).

Example 4

A porous material was obtained in the same manner as in Example 1 except that centrifugation was performed for 5 minutes. Table 1 shows the fiber diameter, average apparent density, and porosity of the obtained porous material. Fig. 5 shows an optical micrograph (magnification: 450 times) of the porous material obtained in Example 4. Table 1. Fiber diameter and porosity of porous material

[Example 5]

Polylactic acid-polyglycolanolic acid copolymer 0.9 g, phosphatidylethanolamine dioleoinole 0.1 g, methylene chloride Zethanol = 7Z2 (parts by weight / parts) 9 g mixed at room temperature (25 ° C) A dope solution having a concentration of 10% was prepared. Using the apparatus shown in FIG. 2, the fibrous material collecting electrode 5 was discharged for 5 minutes. The inner diameter of the ejection nozzle 7 was 0.8 mm, the voltage was 14 kV, and the distance from the ejection nozzle 7 to the fibrous material collecting electrode was 10 cm. 0.2 g of the obtained fibrous material was put into 5 Oml of ION-exchanged water, and cut with a homogenizer (registered trademark POLY TRON PT 2100) at a rotation speed of 22, O 2 O pm for 5 minutes. A part of the obtained suspension was centrifuged for 10 minutes using a centrifuge (KUBOTA KN_70, rotation radius: 15 cm) at a rotation speed of 1 O O Orpm (170 G). Further, the suspension was added thereto, followed by centrifugation at 2, O O O rpm (700 G) for 10 minutes, and in the same manner, and centrifugation was performed at 3,000 rpm (1,500 G) for 10 minutes. Then, after freezing at 20 ° C. for 2 hours, freeze-drying was performed at 2 OPa for 6 hours to obtain a porous body. Table 2 shows the fiber diameter and porosity of the obtained porous body. The sample was sputter coated (Ptl. Onm) and observed with SEM JSM-5310 type (manufactured by JEOL Ltd., acceleration voltage: 2.0 kV, shooting angle 30 °) to determine the fiber diameter.

Fig. 6 shows the upper SEM photo, Fig. 7 shows the middle, and Fig. 8 shows the lower SEM. Table 2. Fiber diameter and porosity of porous materials

[Example 6]

Polylactic one polyglycol Ichiru acid copolymer 1. 5 g, Shioi匕methylene / Etanoru = 7. 5/1 (parts / parts by weight) 8. 5 _§ mixed at room temperature (25 ° 0 to 15 weight ⁰ The dope solution was adjusted to ₀ / _0. Using the apparatus shown in Fig. 3, install an electrostatic remover (Kasuga Electric Co., Ltd.) and a scraper (HE I DON) between the nozzle and electrode. The yarn was discharged for 1 minute, and the yarn spun by the winder 1 9 was wound up to obtain a fiber structure, at which time the rotational speed of the winder was 10 Q r pm. 0.8 mm, voltage is 12 kV, distance from jet nozzle 13 to scraper 19 is 20 cm, distance from jet nozzle 13 to electrostatic eliminator 20 is 35 cm, jet nozzle 1 3 to electrode 1 7 The distance to the tube was 55 cm, and a cylindrical specimen having a diameter of 5 mm and a height of 5 mm was cut out using a biopsy trepan, and the fiber diameter, average appearance, density and The mouth city is shown in Table 3. Figure 9 shows an optical micrograph (magnification: 450 times) of the porous material obtained in Example 6. Compressive strength (10% displacement stress, see JIS standard K72 20) is 0.04 MPa.

[Example 7] A fiber structure was obtained in the same manner as in Example 6 except that the spinning time was 45 minutes and the number of revolutions of the winder was 20 rpm. Table 3 shows the fiber diameter, average apparent density, and porosity of the obtained porous material. FIG. 10 shows an optical microscopic photograph (magnification: 450 times) of the porous body obtained in Example 7. The compressive strength was 0.006 MPa.

[Example 8]

The upper layer was produced with a spinning time of 60 minutes and a winder speed of 100 rpm, and then the lower layer was made with a spinning time of 20 minutes and a winder speed of 20 rpm. A fiber structure was obtained in the same manner as in Example 6. Table 3 shows the fiber diameter, average apparent density, and porosity of the obtained porous material.

'Table 3. Fiber diameter and porosity of porous material

[Example 9]

Using the porous body of Example 3, biological evaluation of the prosthetic material was performed by the following method. (a) Dimethyl sulfoxide: Wako Pure Chemical Industries, Ltd.

(b) Disinfecting ethanol: Wako Pure Chemical Industries, Ltd.

(c) 10% neutral buffered formalin solution: Wako Pure Chemical Industries, Ltd.

(d) Saf r a n i n O solution: Wako Pure Chemical Industries, Ltd.

(e) Fast Green FCF: Polyscience Co., Ltd.

(f) Ethylenediamine 1 N, N, N, N '14 sodium salt 4 anhydride (below EDTA): Dojin Chemical Laboratory

(g) Crystalline penicillin G potassium (hereinafter referred to as penicillin): manufactured by Ariyu Pharmaceutical Co., Ltd.

(h) Iodine tincture: manufactured by Yoshida Pharmaceutical Co., Ltd.

(i) Ketaral for animals: Sankyo Ale Yakuhin Co., Ltd.

(j) Animal Seractal 2% Injection: Bayer (Bayer)

(k) Usagi: The New Zealand White Rabbit used in the experiment (hereinafter NZW Usagi) was male and was purchased from SLC, Inc., and reared normally on a gauge. The age at the time of surgery was 24 weeks.

(Embedding of porous material)

Ketarar and Seractal were given intramuscularly to the hind limb thighs of NZW Usagi that were normally bred, and the following surgery was performed under general anesthesia. The area around the knee joint on both hind limbs was shaved and disinfected with ethanol. Thereafter, the inside of the knee joint was incised, and the femoral patella groove was exposed by dislocation of the patella. The entire thickness of the knee joint cartilage was lost by creating a cylindrical defect part with an inner diameter of 5 mm and a depth of 5 mm with a surgical drill in the pulley groove part about 5 mm above the medial collateral ligament. . After embedding a porous body with an average apparent density of 208 kg / cm ³ (porosity 38%) produced in Example 3 in the defect, the patella was returned to its original position and the muscle was used as a surgical suture. And sutured. Penicillin was dropped on the affected area to prevent infection, and the skin was sutured. Finally, it was sterilized with iodine tincture and returned to Gai'ji for normal breeding.

mm)

At 8 weeks after the operation, it was sacrificed, the defect site was removed, and the cartilage tissue was visually observed, immersed in 10% neutral buffered formalin solution and fixed for histological evaluation. For histological evaluation, the fixed tissue was degreased and EDTA decalcified, then embedded in paraffin, and a specimen was prepared by slicing the vicinity of the center of the defect into a sagittal plane. 0— Fa st Green stained.

A micrograph of the specimen is shown in Fig. 11. The cartilage tissue repaired 8 weeks after the surgery was in the process of forming a layer, and production of cartilage matrix was observed. In addition, it was found that the connection with the normal part was good and the reconstruction of the subchondral bone was taking place. [Example 9] A biological evaluation was carried out in the same manner as in Example 8, using a porous material of Example 4 (average apparent density 100 kg / cm ³ , porosity '70%).

A micrograph of the specimen is shown in Fig. 12. The cartilage tissue repaired at 8 weeks after the operation was formed with a thickness almost equal to that of the normal part, and most of the cartilage was like hyaline cartilage, and the production of cartilage matrix was observed to be good. In addition, the connection with the normal part was good, and continuity of the tissue was observed. ― '

[Comparative Example 1]

Biological evaluation was performed in the same manner as in Example 8 except that the porous material was not embedded in the defect. A micrograph of the specimen is shown in Fig. 13. At 8 weeks after the operation, the cartilage tissue was missing and the subchondral bone was exposed. In addition, the trabecular bone of the subchondral bone was scarce and repair of the cartilage tissue was not observed. Histological evaluation was performed by scoring the following items for Examples 8 and 9 and Comparative Example 1.

The score grade used for histological evaluation is a modified version of Wakitani S et. Al., J Bone Joint Surg Am. 76, 579-92 (1994) Makino T et al., Kobe J Med Sci. 48: It carried out according to 97-104 (2002). Figure 14 shows the items and scores used in the histological evaluation.

The total is 14 points, and it is evaluated on a 3-5 scale depending on the item. The higher the degree of tissue repair, that is, the closer it is to normal tissue, the closer it is to 14 points. In other words, the items are: repaired tissue morphology (0 to .4 points), matrix staining (0 to 3 points), surface condition (0 to 3 points), cartilage tissue thickness (0 2 points from the point), and the degree of connectivity with the non-deficient part (0 to 2 points). In this method, the closer to normal tissue, the higher the score.

The evaluation results are shown in Figure 15. 'In the group embedded with porous bodies, all items showed that the repair of cartilage and weaving progressed better than Comparative Example 1. In addition, when compared with the difference in porosity, there is no significant difference, but the cell morphology is 70% porosity. The tissue was repaired with more hyaline cartilage. These results indicate that a porous body with a certain porosity is effective for repairing cartilage tissue.

Claims

The scope of the claims

■ 1. It consists of a fiber structure of a bioabsorbable polymer, and the fiber structure has an average fiber diameter of 0.05 to 10 111, an average apparent density of 10 to 350 kg / m ³ , and a height of 0.5 ram or more. A porous material that specializes in that.

2. The porous body according to claim 1, wherein an average fiber diameter of the porous body is 0.2 to 8 μm.

3. The porous body according to claim 1, wherein the average apparent density is 100 to 25 Okg / m ³ .

4. The porous material according to claim 3, wherein the porous material has a gradient structure in which the porosity is 10 to 90 ° / ₀ , and different porosity exists continuously.

5. The porous body according to claim 1, further comprising 0.01 to 50 parts by weight of a dispersion aid with respect to 100 parts by weight of the bioabsorbable polymer.

6. The porous body according to claim 5, wherein the dispersion aid exhibits bioabsorbability.

7. The dispersion aid is at least one selected from the group consisting of phospholipids, carbohydrates, glycolipids, steroids, polyamino acids, proteins, and polyoxyalkylenes. The porous body according to claim 6, wherein

8. The porous body according to claim 1, wherein the bioabsorbable polymer mainly comprises an aliphatic polyester.

9. The porous body according to claim 8, wherein the aliphatic polyester is at least one selected from the group consisting of polydalicolic acid, polylactic acid, polystrength prolatatone, and copolymers thereof.

A prosthetic material comprising the porous body according to claim 1.

1 1. A step of spinning a solution comprising a volatile solvent and a bioabsorbable polymer by an electrostatic spinning method to obtain a fiber structure, a step of cutting the obtained fiber structure, and the cut fiber structure as a solvent And a step of centrifuging and centrifuging, followed by a step of freeze-drying, comprising a fiber structure of a bioabsorbable polymer, the average fiber diameter of the fiber structure being 0.05 to 10 ^ m, and the average apparent density being A method for producing a porous body having a thickness of 10 to 3500 kg / m3 and a thickness of 0.5 mm or more.

12. The production method according to claim 11, wherein the solution is further spun using a solution containing a dispersion aid.

1 3. It is characterized by using a static eliminator between the nozzle and the collecting electrode in comparison with a method of spinning a solution composed of a volatile solvent and a bioabsorbable polymer by the electrostatic spinning method. It consists of a fiber structure of a bioabsorbable polymer, and the average fiber diameter of the fiber structure is 0 · 0′5∼: L 0 μ πι, the average apparent density is 10 to 3500 kg / m3, and the thickness is 0 A method for producing a porous body having 5 or more strokes.