JP4717336B2 - Bone regeneration base material and method for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to provision of a bone regeneration base material.
[0002]
[Prior art]
Autologous bone transplantation in which a patient's own normal bone is partially cut out and transplanted into the defect when a large bone loss is caused by trauma or bone tumor is common, but the amount of bone that can be collected for autologous bone transplantation Has a limit, and it also hurts healthy tissue, so the burden on the patient is great. For this reason, allogeneic bone transplantation that transplants the bones of others stored in the tissue bank is also performed, but not only can the allograft be integrated with the patient's own bone, but also in a place far away from the joint. May not be able to reach, so the strength of the same kind of bone may be reduced and it may break. There is also concern about the occurrence of immune rejection.
At present, artificial bones made of artificial materials are being actively developed and are already in use. Such materials do not have to worry about immunological problems and are easy to obtain and process. Therefore, they can be industrially mass-produced. On the other hand, metal materials such as cobalt-chromium alloys and titanium alloys are more difficult than biological tissues. In addition, there is a drawback that the elastic modulus is too high and the toughness is lacking, and further, there is a problem that it is substantially impossible to cope with individual defect shapes in the medical field. In addition, there are many problems such as lack of biocompatibility and infection, and the scope of application is limited.
Bioceramics such as porous hydroxyapatite have high biocompatibility, and are used in large quantities for the purpose of filling bones. However, such inorganic materials have low strength, and their uses are limited. In addition, it is difficult to mold into a special tissue form in advance, and it is extremely difficult to prepare a shape corresponding to each defect in the operating room. Furthermore, in order to improve the cell invasion effect, it is necessary to have a communication hole structure, but it is not easy to provide a communication hole structure with ceramics, and the strength is significantly reduced, so that a satisfactory one can be obtained. Not.
On the other hand, research and development to reconstruct bones by regenerative medical engineering has been actively promoted in recent years. For such bone regeneration, extracellular matrix, bone marrow cells, periosteum, periosteum-derived cells, osteoinductive protein factor, and the like are used. As the base material, for example, a composite material of collagen and bioceramics, or a regenerated base material in which a biodegradable and absorbable material and hydroxyapatite as shown in Patent Documents 1 to 5 are combined are proposed.
However, the former has a problem that the strength is weak and the biodegradation is fast. In the latter case, Patent Documents 3 and 5 do not have a communication hole structure, and Patent Documents 1, 2, and 5 have not been put into practical use.
In such regenerative medical engineering, there is a big problem that the patient has to regenerate bones quickly with a minimum of wounds. However, such regenerative medical engineering should be used for treatment when bone is largely lost. If you can, it will be very useful.
[0003]
[Patent Document 1]
Japanese Patent No. 3243679 [Patent Document 2]
JP 2003-33429 A [Patent Document 3]
JP 2002-325830 A [Patent Document 4]
JP 2003-62060 A [Patent Document 5]
Japanese Patent Laid-Open No. 2001-54564
[Problems to be solved by the invention]
The present invention relates to a bone regeneration base material characterized by a composite of a bioabsorbable organic porous material and a bone-compatible inorganic material, and a method for producing the same, and has high toughness, flexibility and scissors capable of rapidly regenerating bone tissue. It provides a base material that can be easily cut by, for example, and has a feature that it can be easily prepared into a complicated shape in a medical field.
[0005]
[Means for Solving the Problems]
However, the present invention is characterized by the following configurations.
Term. Bone selected from calcium triphosphate (TCP) or hydroxyapatite in a bioabsorbable organic porous body made of a copolymer of lactic acid / ε-caprolactone having a polymerization ratio of lactic acid of 30 to 90% A step of filling the bioabsorbable organic porous material with a bioabsorbable organic porous material by spraying or immersing a dispersion of the affinity inorganic material and processing the mixture under pressure or reduced pressure, and then immersing the biocompatible organic material in ethanol. A method for producing a porous bone regeneration base material comprising a step of fixing an osteophilic inorganic material by contracting an absorbent organic porous material.
2
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the bioabsorbable organic porous material having communication holes constituting the substrate of the present invention include polymers such as lactic acid, glycolic acid, ε-caprolactone, and p-dioxanone, or synthetic polymers such as copolymers and mixtures, collagen And proteins such as gelatin, or natural polymers such as hyaluronic acid and alginic acid. Among these, a lactic acid-ε-caprolactone copolymer that is flexible and easy to mold is particularly preferable.
That is, the lactic acid-ε-caprolactone copolymer can be arbitrarily changed in strength and degradability depending on the polymerization ratio. In order to maintain flexibility and strength as a base material and to easily prepare a target shape in clinical settings, the lactic acid composition in the copolymer is preferably 30 to 90%. If it is less than 30%, sufficient strength cannot be obtained, and if it exceeds 90%, flexibility is lost, which is not preferable.
In particular, such a range is preferably in the range of 50 to 75%. In other words, since the copolymer with 50% lactic acid composition is rich in flexibility, it can be cut into a rough shape and then inserted into the defective portion to cope with the complicated shape. It is. For example, when an internal cancellous bone such as a tubular bone is crushed due to a traffic accident or the like, it is very useful as a bone internal supplement. Further, since a copolymer having a lactic acid composition of 75% has an appropriate strength and flexibility, it can be used after being formed into a middle phalanx shape with scissors, for example.
Examples of the osteophilic inorganic material include tetracalcium phosphate (TTCP), calcium triphosphate (TCP), calcium diphosphate (DCPD), hydroxyapatite, and the like. (TCP) and hydroxyapatite are preferred. The content can be arbitrarily prepared, but is desirably in the range of 10 to 95%, preferably 40 to 90%.
If it is less than 10%, a sufficient bone regeneration effect cannot be obtained, and if it exceeds 95%, strength and flexibility are lost. Although the particle size of this is not specifically limited, It is preferable that it is 10-1000 micrometers.
Examples of the form of the porous body having a communicating hole structure include foams, knitted fabrics, woven fabrics, and nonwoven fabrics.
For example, a base material having a continuous porous body can be easily formed by suspending an osteophilic inorganic material in a solution of a bioabsorbable material and freeze-drying it.
Alternatively, the bioabsorbable material can be freeze-dried in advance to form a continuous porous body, and this void can be filled with a bone-compatible inorganic material using means such as pressurization and decompression. According to this method, the surface of the bone-compatible inorganic material can be combined without being coated with the bioabsorbable material, and the biocompatibility can be sufficiently exhibited.
Furthermore, it can also be obtained by dispersing a bone-compatible inorganic material in a bioabsorbable synthetic polymer solution and spray-drying the dispersion.
Moreover, a continuous porous body can be easily formed by kneading and spinning a bioabsorbable material and an osteophilic inorganic material and taking the form of a knitted fabric, a woven fabric or a non-woven fabric.
The pore diameter of the porous body is about 5 to 500 μm, preferably about 10 to 200 μm. The porosity is 30 to 98%, preferably about 80 to 95%.
Examples of the raw material of the bioabsorbable material that reinforces the porous body include copolymers such as lactic acid, glycolic acid, ε-caprolactone, and p-dioxanone, and the form thereof includes fibers such as monofilament, multifilament, and string. Examples thereof include knitted fabrics, woven fabric sheets, and nonwoven fabrics. The fiber has a diameter of about 10 to 2000 μm, preferably about 50 to 1000 μm. For example, in the above-described foaming by freeze-drying or spray-drying treatment, the fiber is disposed in a solution or on a spray-dried surface, and the end portion, the center It is made to exist in arbitrary positions, such as a part, and is integrated.
Examples of cells that form bone include periosteum, bone marrow, and osteoblasts. The periosteum can be taken from the frontal bone, forearm radius, costal cartilage, iliac bone, femur, and the like.
The base material for bone regeneration according to the present invention quickly regenerates bone tissue and absorbs the porous body itself, so that good tissue regeneration is possible without causing a foreign body reaction. Furthermore, since it can be easily processed into a shape corresponding to the defect in the surgical field, an excellent bone healing effect can be exhibited in the clinical field.
Examples of the present invention will be described below, but this does not limit the present invention.
[0007]
【Example】
Example 1
A 5% dioxane solution of lactic acid-ε-caprolactone copolymer (lactic acid composition 75%) and hydroxyapatite with an average particle size of 30 μm are mixed and suspended at a weight ratio of 35: 4, and then poured into a glass frame and kept at −20 ° C. And immediately frozen. This was freeze-dried at 30 ° C. for 24 hours in a freeze-dryer. The obtained composite base material had a continuous porous structure containing 70% by weight of hydroxyapatite (FIG. 1). This was formed into a middle phalanx shape with scissors, sterilized with ethylene oxide gas at 60 ° C. for 3 hours, and then degassed under vacuum at 60 ° C. for 48 hours. To this base material, the periosteum collected from the calf's forearm portion was sutured and fixed with the lower bone forming layer in close contact with the base material. The substrate was transplanted subcutaneously to the back of nude mice (4-6 weeks, male, average body weight 30 g). As a control, a substrate without hydroxyapatite was used. Nude mice were sacrificed 15 weeks after transplantation, and the tissues were removed. After this fixed tissue was fixed with 10% formalin, it was decalcified with EDTA and dehydrated with ethanol, a paraffin section was prepared, and von Kossa staining was performed for histological examination.
The excised tissue using a composite base material regenerates a good bone tissue that retains the shape of the middle phalane in appearance, and the histological examination also sufficiently regenerates the bone tissue to the inside compared to the control It was confirmed that this composite base material functions as a good bone regeneration base material (FIGS. 2 and 3).
[0008]
Example 2
Dissolve 50 g of poly-L lactic acid (weight average molecular weight 250,000) in 950 g of dichloromethane to prepare a 5% solution, and then add 400 g of hydroxyapatite with an average particle size of 30 μm to prepare a suspension in which hydroxyapatite is uniformly dispersed. did. The obtained suspension was sprayed from a nozzle using an organic solvent spray dryer (Yamato: GS310) (inlet temperature 80 ° C.), and nitrogen gas was sealed and circulated to finally remove poly (L-lactic acid) / dichloromethane / A hydroxyapatite composite substrate was obtained.
The composite base material had a continuous porous structure containing about 90% by weight of hydroxyapatite (FIG. 4).
[0009]
Example 3
A 5% dioxane solution of lactic acid-ε-caprolactone copolymer (lactic acid composition 50%) is poured into a glass frame, immediately frozen at −20 ° C., and then frozen at 30 ° C. for 24 hours in a freeze dryer. Dried. The obtained foam sheet was immersed in about 10% hydroxyapatite suspension and further decompressed to fill the voids of the foam sheet with hydroxyapatite. After removing the hydroxyapatite adhering to the foam sheet surface by lightly washing with water, the hydroxyapatite filled in the voids was fixed by immersing in ethanol to shrink the foam sheet. The obtained composite base material had a continuous porous structure containing about 50% by weight of hydroxyapatite (FIG. 5). This was cut into a disk shape having a diameter of 10 mm, sterilized with ethylene oxide gas for 3 hours at 60 ° C., and then degassed under vacuum at 60 ° C. for 48 hours. Stem cells isolated from the bone marrow of rat femur were seeded on this base material to induce bone differentiation. After 2 weeks of culture, the number of cells was counted, and after 3 weeks of culture, alkaline phosphatase activity was measured. As a control, the same operation was performed with a foam sheet not filled with hydroxyapatite.
As a result, both the number of cells and alkaline phosphatase activity were higher in the hydroxyapatite composite base material, confirming that this composite base material functions as a good bone regeneration base material.
[0010]
【The invention's effect】
Since the regeneration base material is a continuous porous body made of a bone-compatible inorganic material and a bioabsorbable organic polymer material, the bone tissue is quickly regenerated, and the porous body itself is flexible so that scissors and the like can be used in the operating room. Since it can be used or processed by applying heat, bone tissue having the desired shape can be regenerated.
[Brief description of the drawings]
FIG. 1 is a drawing substitute photograph (magnified 300 times) showing a cross section of a composite substrate.
FIG. 2 is a drawing-substituting photograph showing von Kossa staining of an excised tissue using a control substrate.
FIG. 3 is a drawing-substituting photograph showing von Kossa staining of an excised tissue using a composite substrate.
FIG. 4 is a drawing-substituting photograph (magnified 650 times) showing a cross section of the composite substrate.
FIG. 5 is a drawing-substituting photograph (300 × magnification) showing a cross section of the composite substrate.

Claims (1)

Bone selected from calcium triphosphate (TCP) or hydroxyapatite in a bioabsorbable organic porous body made of a copolymer of lactic acid / ε-caprolactone having a polymerization ratio of lactic acid of 30 to 90% A step of filling the bioabsorbable organic porous material with a bioabsorbable organic porous material by spraying or immersing a dispersion of the affinity inorganic material and processing the mixture under pressure or reduced pressure, and then immersing it in ethanol for living A method for producing a porous bone regeneration base material comprising a step of fixing an osteophilic inorganic material by contracting an absorbent organic porous material.

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