JPH047227B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a filling composition for filling bone defects and cavities and generating new bone at the filling sites.

[Prior Art] In the field of surgery or orthopedics, bone defects or voids occur due to fractures or bone tumor excision, and in the field of dentistry, loss of jaw bone due to alveolar pyorrhea occurs. This is often encountered when a prosthesis is required for the area. Conventionally, in many cases, a method has been used in which the patient's own iliac bone or the like is removed and filled into the bone defect site to fill the defect or void in the bone tissue and to hasten the recovery and healing of the tissue. However, using this method requires resection of normal bone tissue other than the damaged area, which causes great pain to the patient and requires a great deal of labor during the surgery. Furthermore, if the bone defect is large, it is not always possible to collect enough autologous bone to fill it, and some kind of substitute must be used to make up for the shortage. As a substitute for this, for example, allogeneic bone and xenogeneic bone are available, but there are still problems such as rejection reactions with the implanted living tissue, and the postoperative course is not always good. It has not yet reached the practical stage.

Various metal alloys and organic substances have been used as hard tissue substitutes for living organisms, but they are said to deteriorate due to dissolution in the living environment, to be toxic to living organisms, and to be accompanied by foreign body reactions. Ceramic materials, which have excellent compatibility with living organisms and do not have the above-mentioned drawbacks, are now being used. Among these ceramic materials, artificial bones and teeth made of sintered bodies or single crystals of alumina, carbon, tricalcium phosphate, or hydroxyapatite, which have excellent biocompatibility, are being developed and are attracting attention.

Attempts have been made to fill bone defects and cavities with these sintered bodies or single crystals, but the shape of the bone defect that requires healing is not constant;
Moreover, they have a complex shape, and it is difficult to process these sintered bodies or single crystals to fit the shape. Furthermore, even if these sintered bodies or single crystals are filled, the surrounding area Because it is significantly harder than bone tissue, the stimulation causes bone resorption around the filling material, causing problems such as loosening, and it has not yet reached the level of practical use.

On the other hand, the sintered body is made into a porous body by mechanical methods or by adding combustible fiber to powder during molding and sintering it, and this is used as a filling material for bone defects and cavities. However, the porosity of the porous body created by these methods is poor, for example, when attempting to mechanically process a ceramic sintered body to make it porous. Moreover, it is impossible to introduce a large amount of pores because the material is brittle and easily damaged. Furthermore, even when flammable fiber is added to ceramic raw material powder and molded and sintered to obtain a porous body, a large amount of flammable fiber is added to the powder. It is difficult to mold the material with high porosity. For this reason, there are drawbacks such as insufficient infiltration of biological osteogenic components necessary for the generation of new bone into the filler, and a long period of time required for the filler and bone tissue to become integrated.

[Objective of the Invention] Therefore, one object of the present invention is to provide a material that has excellent biocompatibility, forms bone tissue in a particularly short period of time without any foreign body reaction, and allows the filling material itself to be absorbed and replaced by the living body, and in particular, to improve the filling composition. It is an object of the present invention to provide a composition for filling bone defects and cavities that can generate new bone up to the center of the object.

Another object of the present invention is to promote bone formation in the filled area and to particularly quickly repair and restore the structure and function of the bone tissue defect area.
An object of the present invention is to provide a composition for part filling.

Still another object of the present invention is to provide a composition for filling bone defects and cavities in which new bone formation is particularly rapid.

Still another object of the present invention is to provide a composition for filling bone defects and cavities that is easy to mold into a shape that matches the shape of the filling site.

The above and other objects of the present invention will become more apparent from the following description.

[Structure of the Invention] According to the present invention, 5 to 95% by volume of hydroxyapatite and fibrin 95% heat-treated at 500°C or higher
There is provided a composition for filling bone defects and cavities, characterized in that it contains ~5% by volume.

[Description of the invention] The present invention will be explained in more detail below.

The hydroxyapatite used in the present invention is hydroxyapatite heat-treated at 500° C. or higher, and hydroxyapatite heat-treated at 700° C. or higher is particularly preferred because new bone formation is particularly rapid. The upper limit temperature of the heat treatment is not particularly limited, but since hydroxyapatite starts to decompose, it should be lower than the decomposition temperature. In addition, the hydroxyapatite used in the present invention may be artificially synthesized by known manufacturing methods such as wet, dry, or hydrothermal methods, or it may be a natural product obtained from bones etc. Good too.

On the other hand, fibrin used in the present invention is prepared using fibrinogen obtained from human or animal plasma as a raw material. From the viewpoint of biocompatibility, when the target is a human, it is preferable to use fibrinogen obtained from human plasma as the raw material, and when the target is an animal, it is preferable to use fibrinogen obtained from the plasma of that animal as the raw material. As such fibrinogen, medical dry fibrinogen manufactured in accordance with the Biological Product Standards (1979, pp. 201-203) supervised by the Pharmaceutical Affairs Bureau of the Ministry of Health and Welfare can be used, and this commercially available product is available under the trade name " There is a powder called "Fibrinogen Midori" [Midori Juji Co., Ltd.].
This is made by adding coagulating proteins and monosaccharides such as sodium citrate and glucose, fructose, and mannite as stabilizers to dried fibrinogen.
7 in low salt buffer. A 0.01 to 0.03 molar citrate buffer is suitable as this low salt concentration buffer. The dissolution temperature is 32 to 36°C, and it is preferable to maintain the inside of the bottle containing fibrinogen under reduced pressure during dissolution. Under these dissolution conditions, dry fibrinogen powder has a
Melts within the range of 10W/V%. Further, fibrinogen may be used in powder form. As detailed below, fibrinogen is solidified into fibrin by adding thrombin and calcium chloride as solidifying agents when preparing the composition for filling bone defects and cavities of the present invention.

In preparing the composition for filling bone defects and cavities of the present invention, the above-mentioned hydroxyapatite powder or granules (hereinafter collectively referred to as powder or granules) or granules made from the powder are used. In some cases, the above-mentioned porous body of hydroxyapatite is used.

When using hydroxyapatite powder, for example, in a wet method, it is obtained as a precipitate, so it is separated from the solution by filtration or centrifugation, dried, and then pulverized. Apatite powder is obtained. In addition, in the case of a wet method and a hydrothermal method, pulverization is also carried out as necessary. When using natural hydroxyapatite such as bone, pulverization treatment is similarly performed. In any case, in the case of granular materials, it is preferable to use particles up to 5 mm in size, although it depends on the size of the defective portion, in order to form the filling composition of the present invention.

The hydroxyapatite powder obtained in this manner can be used as it is as the filling composition of the present invention, but it is necessary to improve the crystallinity of the particles and improve biocompatibility, and to prevent infection by bacteria and rejection by organic substances. In the case of hydroxyapatite obtained by wet synthesis, it is necessary to heat sterilize it sufficiently to prevent If so, it is preferable to carry out appropriate pulverization treatment to form powder or granules.

The powder and granules obtained by each of the above synthesis methods and the powder and granules obtained by further calcination are further added with a liquid such as water or physiological saline, and then processed using a rolling granulator or the like. It can also be used to form granules. The particle size of the granules is not particularly limited, but is preferably about 0.1 to 5 mm in order to manufacture the filling composition of the present invention and to prevent the granules from flowing out to other parts of the body.

In either case, a mixture of a fibrinogen solution or powder and the aforementioned hydroxyapatite powder or granules is prepared. Separately, a mixed solution is prepared in which thrombin and calcium chloride are dissolved in physiological saline or citrate buffer as a solidifying agent for solidifying fibrinogen into fibrin. Usually, it is preferable to include 1 to 500 NIH units/ml of thrombin and 10 to 100 mmol/ml of calcium chloride.If it is less than the lower limit, fibrinogen may not solidify sufficiently, whereas if it is added above the upper limit, it will not solidify. In many cases, the effects do not change much. A protease inhibitor may be added to the mixed solution in order to prevent fibrin from being dissolved depending on the site to be filled with the composition for filling bone defects and cavities of the present invention. Plasmin inhibitors can be preferably used as protease inhibitors,
Examples include aprotinin, epsilon aminocaproic acid, planexamic acid, soybean trypsin inhibitor, and the like. The amount of protease inhibitor added is usually about 100 to 5000 KIE units/ml.

Next, when the above-mentioned mixture of fibrinogen and hydroxyapatite and the above-mentioned mixed solution are mixed and stirred, thrombin and calcium chloride insolubilize the fibrinogen to form fibrin in about 10 to 30 minutes, and granules of hydroxyapatite are formed in the colloidal fibrin. Alternatively, the composition for filling bone defects and cavities of the present invention in which the granules are dispersed can be obtained.

Since it takes about 10 to 30 minutes for fibrinogen to solidify with thrombin and calcium chloride, a mixed solution of thrombin and calcium chloride is added to the fibrinogen solution or powder, and then hydroxyapatite powder or granules are added to the fibrinogen solution or powder. The composition for filling bone defects and cavities of the present invention can also be obtained by adding and stirring and mixing.

As mentioned above, the composition for filling bone defects and cavities of the present invention can also be prepared using a porous body of hydroxyapatite. In this case, for example, the aforementioned hydroxyapatite powder is suspended in a liquid such as distilled water to form a slurry, and the slurry of hydroxyapatite is applied to a spongy organic porous body having continuous pores in a three-dimensional network structure. A porous body of hydroxyapatite can be prepared by impregnating, drying, and heating the organic porous body to burn it out. Next, after immersing hydroxyapatite in the fibrinogen solution or powder described above, the mixed solution containing thrombin, calcium chloride, and optionally a protease inhibitor is added dropwise to solidify the fibrinogen, thereby forming continuous pores in the hydroxyapatite porous body. The composition for filling bone defects and cavities of the present invention, which is filled with fibrin, is obtained. As mentioned above, the reaction of fibrinogen with thrombin and calcium chloride takes some time, so a mixed solution containing thrombin and calcium chloride is added to the fibrinogen solution or powder, and the hydroxyapatite porous material is immediately immersed or reacted with the mixture. The composition for filling bone defects and cavities of the present invention can also be obtained by dropping it onto a porous body.

The blending ratio of hydroxyapatite and fibrin in the composition for filling bone defects and cavities of the present invention should be 5 to 95% by volume of hydroxyapatite and 95 to 5% by volume of fibrin in the final product composition. Hydroxyapatite is 5
If the fibrin content is less than 95% by volume, the formation of new bone may be delayed, while if it exceeds 95% by volume, the content of fibrin will be low and new blood vessels will be less likely to form.

[Effect] Hydroxyapatite has an osteogenic effect, and when filled into bone defects or cavities, new bone is formed. On the other hand, fibrin is a hard protein obtained by the action of fibrinogen and thrombin, and has the function of adhering the wound surface. Due to this adhesion, fibroblasts are generated on the wound surface, which eventually become fibrous cells and fix the tissue. At the same time, blood vessels are generated within the tissue. Therefore, in the present invention, hydroxyapatite is held in a fixed state by the adhesive action of fibrin, and the osteogenic action of hydroxyapatite is promoted, as well as angiogenesis is promoted to form new bone, thereby repairing living tissue. It can be sped up. In particular, when the composition for filling bone defects and cavities of the present invention is filled, new blood vessels are formed and extended to the center of the composition, and new bone is rapidly formed.

The composition for filling bone defects and cavities of the present invention is stored under sterile conditions in physiological saline or a low salt concentration buffer with a pH of 6 to 7, such as a 0.01 to 0.03M citrate buffer, If necessary, one that matches the shape of the bone defect or, for example, approximately 1 mm to 15 cm.
It can be cut into sections and the required amount can be filled into bone defects or cavities.

[Example] Next, the present invention will be explained with reference to its embodiments.

Example 1 60 mg of fibrinogen extracted and purified from rabbit blood was dissolved in citrate buffer (PH6).
A composition (hereinafter abbreviated as fibrin composition) was prepared by adding 1 ml of a 40 mM calcium chloride solution containing 4 NIH units/ml of thrombin and 3000 KIE units/ml of aprotinin to the % solution. Next, hydroxyapatite powder (calcined at 900°C) was mixed with the fibrin composition at a volume ratio of 1:1 and solidified to prepare a composition for filling bone defects and cavities of the present invention. It was cut out into pieces of size and placed in 0.01M citrate buffer. In addition, tricalcium phosphate powder (calcined at 1150°C) and tetracalcium phosphate powder (calcined at 1350°C) were mixed into the fibrin composition at a volume ratio of 1:1, respectively, and the same process was performed to obtain a size of 5 x 4 x 3 mm. It was cut into pieces and placed in 0.01M citrate buffer.

Next, a hole of 5 x 4 x 3 mm was made in the rabbit femur, filled with the above composition of the present invention, and the progress was observed after 4 weeks. Separately, only the fibrin composition, only the hydroxyapatite powder, only the tricalcium phosphate powder, and only the tetracalcium phosphate powder were filled into the holes, and the progress after 4 weeks was observed. In this case, as a control, only a hole was made and nothing was filled, and the progress was also observed.

As a result, when the composition for filling bone defects and cavities, which is a combination of the fibrin composition and hydroxyapatite of the present invention, was filled, new bone formation was observed up to the center, and tricalcium phosphate and New bone formation was greatest compared to the combination of tetracalcium phosphate and fibrin.

On the other hand, when only the fibrin composition was filled or when only a hole was made, the defect was filled with soft tissue, and only a small amount of new bone was observed around the defect.

hydroxyapatite, tricalcium phosphate,
When only tetracalcium phosphate was used, although new bone formation was observed inside the filler, almost no new bone was observed in the center of the filler.

Example 2 Fibrin composition and hydroxyapatite powder (calcined at 1200°C) in volume ratios of 40:1, 20:1, 1:1,
Mix and solidify in the same manner as in Example 1 at a ratio of 1:20 and 1:40, cut this into 5 x 4 x 3 mm, and place it in the same solution as in Example 1 to prepare each sample. Fill the 5 x 4 x 3 mm hole drilled in the rabbit femur, and
I observed the situation after a week.

As a result, new bone formation was observed up to the center of the hole with the mixtures with volume ratios of 1:20, 1:1, and 20:1, but with the mixtures with volume ratios of 40:1 and 1:40. No new bone had been generated up to the center of the hole.

Example 3 Using human-derived fibrinogen, Example 1
A fibrin composition was prepared in the same manner as above, and hydroxyapatite (granules fired at 800°C, particle size 2.0~
1.0 mm) was added at a fibrin composition: hydroxyapatite = 1:10 (volume ratio) and solidified, cut into 5 x 5 x 5 mm to prepare a sample, and placed in the same solution as in Example 1. Ta.

A bone tumor occurring in a human femur was excised and filled with the sample, and the progress after filling was observed using X-rays and bone scintigraphy. As a result of X-ray observation, new bone formation was observed from 1 week after the surgery, and from 3 to 3 days after surgery.
After 4 weeks, the boundary between the filled sample and the living bone became unclear. On the other hand, bone scintigraphy shows that preoperative
The tumor area, which had been cold, became hot after the surgery, suggesting that active bone formation was occurring.

Example 4 A hydroxyapatite porous material (calcined at 1200°C, porosity 80%) was immersed in the fibrinogen-containing solution used in Example 1, and then taken out. A calcium solution was added dropwise to prepare a composition for filling bone defects and cavities of the present invention. A sample was prepared by cutting out this composition into a size of 5 x 4 x 3 mm, and the sample was placed in 0.01M citrate buffer.

Next, a hole of 5 x 4 x 3 mm was made in the rabbit femur and filled with the above sample. When the progress was observed after 4 weeks, new bone formation was observed up to the center of the filled sample.

Claims (1)

[Claims] 1. A composition for filling bone defects and cavities, characterized by containing 5 to 95 volume % of hydroxyapatite and 95 to 5 volume % of fibrin that have been heat-treated at 500°C or higher.