[Formation of bone in critical calvarias defects in rats under the influence of bisphosphonate alendronate Na complex]. / Novoobrazovanie kostnoi tkani v kriticheskikh defektakh svoda cherepa krys pod vliyaniem kompleksa, soderzhashchego bisfosfonat alendronat natriya.

The aim of the study was to investigate dynamic of tissue structures in critical defects of calvaria of rats after inoculation of bisphosphonate (BF) alendronate Na complex into bone defects. Animal model included 24 Wistar rats divided in 3 groups: spontaneous healing under blot clot (1), inoculation of carbonate hydroxide apatite ß-tricalcium phosphate blocks (2) and BF alendronate Na complex (3) on 15, 30, 60 and 90 experiment day. New bone formation was observed in group 3 as opposed to groups 1 and 2.

Tissue engineering construct on the basis of multipotent stromal adipose tissue cells and Osteomatrix for regeneration of the bone tissue.

We developed a new method of creation of tissue engineering constructs for regeneration of the bone tissue based on the principle of free distribution of cells in a fibrin clot within a scaffold. The tissue engineering construct includes multipotent stromal adipose tissue cells committed in osteogenic lineage, platelet-rich plasma, and resorbed material on the basis of xenogeneic bone collagen. The culture of bone progenitor cells was characterized by the main markers of osteoblastic differon. The material meets all requirements for materials intended for tissue engineering. An innovative high-technological tissue engineering product for clinical application is prepared.

Regeneration of skull bones in adult rabbits after implantation of commercial osteoinductive materials and transplantation of a tissue-engineering construct.

We performed a comparative study of reparative osteogenesis in rabbits with experimental critical defects of the parietal bones after implantation of commercial osteoinductive materials "Biomatrix", "Osteomatrix", "BioOss" in combination with platelet-rich plasma and transplantation of a tissue-engineering construct on the basis of autogenic multipotent stromal cells from the adipose tissue predifferentiated in osteogenic direction. It was found that experimental reparative osteogenesis is insufficiently stimulated by implantation materials and full-thickness trepanation holes were not completely closed. After transplantation of the studied tissue-engineering construct, the defect was filled with full-length bone regenerate (in the center of the regenerate and from the maternal bone) in contrast to control and reference groups, where the bone tissue was formed only on the side of the maternal bone. On day 120 after transplantation of the tissue-engineering construct, the percent of newly-formed bone tissue in the regenerate was 24% (the total percent of bone tissue in the regenerate was 39%), which attested to active incomplete regenerative process in contrast to control and reference groups. Thus, the study demonstrated effective regeneration of the critical defects of the parietal bones in rabbits 120 days after transplantation of the tissue-engineering construct in contrast to commercial osteoplastic materials for directed bone regeneration.

Porous materials from titanium-cobalt alloys for hybrid implants.

We proposed a new method to increase the biocompatibility of porous materials that were synthesized from titanium and cobalt allows by the method of self-propagating high-temperature synthesis. This method suggested the introduction of calcium hydroxyapatite into the reaction mixture. Administration of calcium hydroxyapatite into the reaction mixture had a modifying effect on the structure and surface of the pore space and biocompatibility of composite materials. Administration of calcium hydroxyapatite crystals was followed by a significant decrease in the size of pores and appearance of water-soluble fractions, which inhibited the activity of cells. However, treatment with amorphous nanodispersed calcium hydroxyapatite increased the biocompatibility and adhesiveness of materials for mesenchymal stem cells. The pore space and mechanical characteristics of materials obtained with amorphous nanodispersed calcium hydroxyapatite were similar to the properties of natural bone. Moreover, these materials surpassed titanium-cobalt allows in biocompatibility. Our results indicate that the introduction of amorphous nanodispersed calcium hydroxyapatite into the reaction mixture during self-propagating high-temperature synthesis has a modifying effect on the pore space of composite materials and increases their biocompatibility and adhesiveness for cells. We conclude that these materials may be used as a carrier of stem cells and progenitor cells in hybrid implants.

Reparative osteogenesis during transplantation of mesenchymal stem cells.

Reparative osteogenesis was studied after xenotransplantation of suspension cell graft from human mesenchymal stem cells. A model of experimental damage to rat femoral diaphysis was developed. The state of animals was satisfactory and non-depressed in the early and late postoperation period. We revealed no local pathological reactions and complications. Administration of mesenchymal stem cells into the area of bone defect accelerated and improved regeneration. Unilateral transplantation of the cell graft stimulated regeneration in the contralateral limb due to acceleration of bone tissue maturation. On day 90 after treatment the bone regenerate was completely developed in the area of defect in animals of various groups. The newly formed bone tissue was well integrated into the bone organ.

Stimulation of reparative osteogenesis after xenotransplantation of human prenatal mesenchymal stem cells and chondroblasts.

Regeneration of the bone tissue after unilateral xenogeneic transplantation of a suspension of human mesenchymal cells and chondroblasts was studied in rats with experimental damage to both femurs. The state of animals was satisfactory and non-depressed in the early and late postoperation period. No local pathological reactions and complications were seen. Administration of mesenchymal stem cells and chondroblasts into the area of bone defect accelerated regeneration on days 10 and 30 (compared to the control group). Implantation of mesenchymal stem cells more significantly stimulated reparative osteogenesis compared to treatment with chondroblasts. This was mainly associated with increased ratio of mature lamellar bone tissue. Unilateral transplantation of the cell suspension stimulated regeneration in the contralateral limb due to accelerated maturation of the bone tissue. The bone tissue formed after transplantation of mesenchymal stem cells and chondroblasts was integrated into bone organ and underwent complete remodeling. Xenotransplantation of prenatal mesenchymal stem cells and chondroblasts without immunosuppression was not followed by the development of early and delayed complications or local reactions of graft rejection.