WO2014058344A1

WO2014058344A1 - Biocompatible bone replacement material and method for producing same

Info

Publication number: WO2014058344A1
Application number: PCT/RU2013/000073
Authority: WO
Inventors: Любовь Константиновна ПОЛЕЖАЕВА
Original assignee: Общество с ограниченной ответственностью "СТАЛВЕК"
Priority date: 2012-10-10
Filing date: 2013-02-01
Publication date: 2014-04-17
Also published as: RU2494721C1

Abstract

The invention relates to medicine, and more particularly to the production of biocompatible materials which can be used as bone replacement agents for filling defects in bone and cartilage tissues in traumatology, orthopedics and neurosurgery in the case of congenital and acquired diseases, and further relates to a drug delivery system. The biocompatible bone replacement material has through pores with a size of 0.7-100 μm and has a total porosity of 50-85%. The material is produced on the basis of a curing reaction mixture of biological hydroxyapatite and magnesium phosphate powders with particle sizes no greater than 40 μm, said mixture containing 2-amino-5-guanidinovaleric acid (arginine), and a tempering fluid (liquid phase) containing a solution of chitosan in succinic acid and a solution of sodium alginate. The curing agent calcium chloride is added to the material prior to use. The invention makes it possible to produce a bone replacement material which is fully biocompatible with bone tissue and exhibits biodegradability, and creates conditions that render bone tissue transplants and reoperation unnecessary.

Description

Biocompatible bone substitute material and method for producing it.

The invention relates to medicine, namely to the production of biocompatible materials that can be used as osteoplastic agents for filling defects in bone and cartilage tissue in traumatology, orthopedics, neurosurgery for congenital and acquired diseases and to the drug delivery system and provides an increased ability for osseointegration and stimulates the reparative processes of bone formation with the restoration of a normal bone matrix.

Osteoplastic materials are widely used in filling defects in the musculoskeletal system, in dentistry, maxillofacial surgery and traumatology. An important role is played by the properties of the inorganic filler, which depend on its chemical composition, source of synthesis, and synthesis method. Obtaining hydroxyapatite from natural material has several advantages over synthetic material, since valuable microelement and phase compositions are retained that are as close as possible to the composition of human bones.

Long-term clinical experience with the use of bone-substituting materials has determined the main requirements for them:

- implant materials must be biocompatible with the recipient's body;

- the chemical composition of the structure and properties should be close to the composition of bone tissue;

- the material should not change the chemical composition in the zone of contact with the body;

- possess the ability to replace defects in a liquid or viscous state of complex anatomical shape, heterogeneous in structure and structure. Calcium phosphate cements are obtained on the basis of a reaction-hardening powder mixture (RPS) of two or more calcium phosphates and a solidifying liquid (GC). The starting powder is a mixture of acidic and basic phosphates. When GI is added to the mixture, the components begin to interact with each other through the liquid phase by the dissolution-precipitation mechanism with the formation of neutral (pH7) phosphates. Tricalcium phosphate in combination with calcium hydroxide or calcium carbonate was used as the initial mixture (S. Tagaki, LCChow, K. Ishikawa, “Formation of hydrohyapatite in new calcium phosphate cements”, Biomaterials, 19 (1998), pp 1593-1599). amorphous calcium phosphate with calcium hydroxide, dicalcium phosphate with calcium hydroxide or calcium carbonate. An aqueous solution of sodium hydroxide or disubstituted sodium orthophosphate was used as a ZH. When a mixture of calcium phosphate powders is mixed with a coolant, a dough-like mass is formed, which over time sets to form a strong hydroxyapatite cement stone consisting of crystalline hydroxyapatite (HA).

The proposed materials can be used as cement pastes for filling bone maxillofacial and dental defects. The disadvantages of these materials is low strength.

Another phosphate cement is known (V.V. Samuskevich, N.Kh. Belous,

L.N. Samuskevich, A.A. Doryshevskaya. Water-based cement based on hydroxyapatite, heat-treated calcium dihydrogen phosphate. Inorganic Materials, 2000, vol. 36, N ° 9, p.1148-1 152), consisting of a mixture of powders of hydrosciapatite (HA) and heat-treated calcium dihydrogen phosphate, water is used as a coolant. With the addition of a shutting fluid, the components of the mixture react with each other with the formation of an amorphous phase, which during the setting process turns into crystalline HA. A significant drawback of this material is its low strength and quick setting time - 2-3 minutes. Fast setting and low strength do not allow the formation of bone implants of complex configuration, heal bone defects of a large area and volume.

It is known from the prior art that chitosan is a biocompatible and biodegradable natural polymer, which allows it to be used in various fields of medicine, including for the rapid healing of wounds and various etymologies. (Chitin and Chitosan. Obtaining, properties and application. Edited by Academician of RAAS KG Skryabin. Science. 2002. 365 pp.). Especially widely used are chitosan materials in the form of plastic porous sponges. Due to plasticity and porosity, these materials are easily deformed to the required size (bone defect) and after being placed in a compressed state in the bone defect, they are straightened (due to reverse deformation), filling the volume of the defect. By its nature, chitosan is a polysaccharide nutrient that promotes bone formation. However, pure chitosan sponges do not contain elements such as phosphorus and calcium that are important for bone formation. Therefore, during the resorption of clean sponges in the bone defect, mainly cartilage tissues (chondroid) are formed.

It is possible to create favorable conditions for the formation of natural bone tissue by using composite materials based on chitosan sponges containing calcium phosphate fillers. Composition sponges based on chitosan (CHCH) containing tricalcium phosphate (Yong-Moo Lee, Yoon Jeong Park et al. Tessie Engineered Boon Formation Used Chitosan / Tricalcium Phosphate Sponges // J. Periodontol, vol. 71, Z, 2000). Composite sponges were prepared by mixing tricalcium phosphate powder with a chitosan solution. Then, excess water was removed from the solution by drying-freezing. Upon freezing, an aqueous solution crystallizes in the form of ice particles from the initial solution, which is then removed by drying in vacuum. As a result, in place of removed ice pores with a size of about 10 microns are formed. The disadvantage of the obtained CHCH is the use of special equipment (freeze drying), as well as the use for the polymerization (stitching) of sponges of an environmentally harmful tripolyphosphate solution.

From RU2292867, 02/10/2007, a material for filling bony maxillofacial and dental defects is known. The material is based on a reaction-hardening mixture of powders containing hydroxyapatite and dicalcium phosphate and tricalcium phosphate, and a solution of magnesium phosphate and potassium phosphate in phosphoric acid is used as a shutter liquid at a certain quantitative content of them in the shutter liquid, while the amount of the shutter fluid is the amount of the reaction-hardening mixture is (g): 0.25-0.65. Inexpensive starting components and high strength make it possible to widely use this material for correlation of fragments of the alveolar ridge, closure of cavities in bone tissues and treatment of various cracks of traumatic origin.

The known material is obtained as follows: powders of hydroxyapatite, dicalcium phosphate and tricalcium phosphate are mixed in a vibratory mill with corundum balls for 20 minutes. The resulting reaction-hardening mixture is mixed with a solidifying liquid (40 wt.% Magnesium phosphate and 40 wt.% Potassium phosphate, phosphoric acid 12 wt.%, 8 wt.% Water). Mixing is carried out for 1-2 minutes with a metal spatula on glass until a sour cream-like state, after which the mixture is placed in a cylindrical shape with a diameter of 0.8 cm. After a few minutes, the molded sample is taken out and placed in a thermostat at a temperature of 37 ° C and a relative humidity of 100% . After 24 hours, the cured sample has a compressive strength of 10 MPa.

However, this material does not possess the necessary complex of properties such as biocompatibility, bioactivity, osteoinductive and osteoconductive properties. The technical task and the achieved technical result of the claimed invention is to obtain an osteoplastic material, which, after filling in bone defects during curing, forms a material that is an analogue of the inorganic component of bone tissue, which has biocompatibility, bioactivity, osteoconductive and osteoinductive properties, due to which it is processed by the body into natural bone tissue, effectively repairing existing defects.

The stated technical problem is achieved by the claimed group of inventions, which includes a biocompatible bone substitute material and a method for its preparation.

So, the stated technical problem is achieved by a method for producing a biocompatible bone substitute material, including obtaining a biological hydroxyapatite powder from cattle bones with a particle size of not more than 40 microns, mixing the obtained biological hydroxyapatite powder with magnesium phosphate powder with a particle size of not more than 40 microns with a ratio of 1 , 0: 0.25, adding to the resulting mixture of powders an aqueous suspension of 2-amino-5-guanidinovalerianic acid, followed by stirring them for 40-50 minutes, and drying at 50-60 ° C, the resulting powder reaction-hardening mixture is then combined with a liquid phase-hardening liquid containing a solution of chitosan in a 3% aqueous solution of succinic acid and a 2% aqueous solution of sodium alginate in a ratio of 0.3 : 0.7, while the ratio between the liquid phase and the powder hardening reaction mixture is 1.0: 0.5, and then a hardener 5-10% aqueous solution of calcium chloride is added to the obtained plastic mass before use, at a ratio of 1.0: 0.3.

The stated technical problem is also achieved by a biocompatible bone-substituting material having through pores of 0.7-100 μm and a total porosity of 50-85%, based on a reaction-hardening mixture powders of biological hydroxyapatite and magnesium phosphate with a particle size of not more than 40 μm, containing 2-amino-5-guanidinovalerianic acid, and a solidifying liquid containing a solution of chitosan in succinic acid and an aqueous solution of sodium alginate, and cured immediately before use with a calcium chloride hardener.

Used in the claimed group of the invention, biological hydroxyapatite is obtained from bones of cattle, for example, by washing with water to remove contaminants and then annealing them at a temperature of 1100-1200 ° C for 2-4 hours. The selected temperature is necessary and sufficient to remove organic components and give bones fragility for further grinding.

The resulting hydroxyapatite is crushed to obtain powder particles with a size of not more than 40 microns (1-40 microns). This method allows to obtain a powder of hydroxyapatite with a microelement composition as close as possible to the composition of human bone tissue. To increase the osteogenic and plastic properties of the material, a magnesium salt is introduced into its composition. It was experimentally established that the particle size of the filler no more than 40 microns plays a decisive role in the dissolution rate of the components, and, therefore, has an effect on the solidification time of the material. The powder size must be adjusted in order to minimize differences in dissolution rate, namely, a powder with a particle size of more than 40 microns and with a specific surface area of about 40-50 m / g dissolves slowly, while a powder with a particle size of less than 40 microns and the specific surface area of the order of 70-90 m ² / g dissolves quickly and leads to a quick setting of the material.

Magnesium is an indispensable element of the triad Ca, P, Mg, the exchange of which is closely interconnected. Thanks to magnesium, the structure of cells becomes more stable during their growth, and the regeneration and renewal of cells of tissues and organs is more effective. Magnesium Stabilizes Bone structure and gives bones strength. Calcium without magnesium cannot be absorbed by the body.

Magnesium phosphate is dried at a temperature of 80-100 ° C to remove adsorbed water from its surface. Next, the magnesium phosphate powder is sieved through sieves with a mesh size of not more than 40 μm (1 -40 μm). Then the powder of hydroxyapatite and magnesium phosphate is mixed in a ratio of 1: 0.25 and mixed in a ball mill for 15-20 minutes. Next, prepare a 2% aqueous solution of a-amino-5-guanido-valerianic acid (arginine) in the form of a suspension, and add to the mixture of powders. The introduction of a-amino-5-guanido-valerianic acid is necessary to increase the proliferation of osteogenic cells. The resulting mass is stirred in a ball mill for 40-50 minutes and dried at a temperature of 50-60 ° C to remove excess water and to prevent decomposition of arginine (a-amino-5-guanido-valerianic acid). Then prepare the liquid phase, consisting of a 1% solution of chitosan and a 2% solution of sodium alginate in a ratio of 0.3: 0.7, respectively. A solution of chitosan (molecular weight 700 kDa) is prepared by dissolving it in a 3% solution of succinic acid.

It is known from the prior art that chitosan - hemostatic, fungistatic, immunomodulator, has an antitumor effect, is a natural biopolymer and has complete biocompatibility with body tissues, which allows it to be used in various fields of medicine. The choice of succinic acid as a solvent for chitosan is due to the fact that succinic acid stimulates the processes of oxygen supply to cells, restores energy exchange, normalizes the production of new cells, and has general strengthening and restoring properties.

Sodium alginate is necessary as a substance that prevents the leaching of material from bone cavities.

A 2% sodium alginate solution was prepared by dissolving in distilled water. The following is an example embodiment of the invention, illustrating it, but not limiting its scope. Example.

The material immediately before use is prepared as follows: a powder mixture based on hydroxyapatite, magnesium phosphate and arginine (a-amino-5-guanidovalerianic acid) is introduced into the liquid phase consisting of a solution of chitosan and sodium alginate (the ratios are given above) and intensively mixed to obtain a homogeneous plastic mass within 1-2 minutes. The ratio of liquid to powder is 1: 0.5, respectively. As a hardener, a 5-10% solution of calcium chloride is used, which is added to the resulting plastic mass in a ratio of 0.3: 1, respectively. This ratio of components is necessary for optimal solidification time of the material (about 10-15 minutes), as well as obtaining a material containing through pores of a certain size.

As a result of tests, it was found that the proposed bone substitute material has complete biocompatibility with bone tissue, biodegradability, and creates conditions that exclude the need for bone transplantation and reoperation.

The technical result of the invention is a bone substitute material based on biophosphates and natural polymers with the addition of 2-amino-5-guanidinovalerianic acid (arginine), which has biocompatibility, biodegradation, osteoinductive, osteoconductive properties and is completely replaced by bone tissue. The resulting material has a through pore size of 0.7-100 microns, the total porosity of 50-85%.

In order to prove the increased ability of the biomaterial to osseointegration and stimulate the reparative processes of bone formation with the restoration of normal bone matrix operations were performed on 20 female Wistar rats at the age of 3 months. In order to identify the systemic reactions of the body to new materials, a set of laboratory studies was carried out, including the necessary biochemical parameters, to determine the local effect of our materials, X-ray studies were performed on the CT, and histological preparations of the tissues surrounding the material were also prepared and studied. In the course of studies, it was found that the material has pronounced biocompatible, osteogenic properties, and is also a stimulator of reparative processes of bone formation with the restoration of normal bone matrix, which is confirmed by x-ray, histological and biochemical research methods.

Claims

Claim

1. A method of obtaining a biocompatible bone substitute material, which consists in obtaining a powder of biological hydroxyapatite with a particle size of not more than 40 microns from bones of cattle, mixing the resulting powder of biological hydroxyapatite with a powder of magnesium phosphate with a particle size of not more than 40 microns with a ratio of 1.0: 0.25, adding to the resulting mixture of powders an aqueous suspension of 2-amino-5-guanidinovalerianic acid, followed by stirring them (in a ball mill) for 40-50 minutes and drying at 50-60 ° C, then semi The cured powder reaction-hardening mixture is combined with a liquid phase-hardening liquid containing a solution of chitosan in a 3% aqueous solution of succinic acid and a 2% aqueous solution of sodium alginate at a ratio of 0.3: 0.7, the ratio between the liquid phase and the powder mixture is 1, 0: 0.5, then a hardener 5-10% aqueous solution of calcium chloride is added to the obtained plastic mass before use in a ratio of 1.0: 0.3.

2. The biocompatible bone substitute material obtained by the method according to claim 1, having through pores of 0.7-100 μm and a total porosity of 50-85%, based on a reaction-hardening mixture of biological hydroxyapatite powders with particle sizes of not more than 40 μm and magnesium phosphate with a particle size not more than 40 μm containing 2-amino-5-guanidinovalerianic acid and a solidifying liquid containing a solution of chitosan in succinic acid and an aqueous solution of sodium alginate, and cured immediately before use with a calcium chloride hardener.