| With the development of nanotechnology, polymer nanocomposites have become a type of essential materials used in bone repair in recent years . In the past several years, the study on nano-material for bone repair mainly focused on structure and properties of the material, however, recently new researches on better materials for bone deficiency revealed a trend, that bio-active ingredients will gradually be loaded into bone tissue engineering scaffolds to promote bone repair. A good biocompatibility is required to ensure the safety of clinical application of biological materials. Deer horn has been used pharmaceutically for thousands of years in China. It is the only type of mammalian bone which is capable of regenerating bone tissue. Foreign scholars research data shows that there is indeed a variety of growth factors in antler known as Insulin-like Growth Factor I (IGF-1), Growth Hormone (GH), and TGFβ1 and TGFβ2 which are related with bone growth and bone remodeling. Therefore it is believed that the co-existence of these growth factors and the combined effect greatly contribute to the rapid growth of antler. A great quantity literature revealed that Velvet Antler Polypeptides extracted from fresh deer antler is actually the major pharmacologically active component of deer antler, which promotes cell differentiation of mesenchyma stem cells, as well as cell proliferation of chondrocytes, epidermal cells, fibroblast and so on. Velvet Antler polypeptides significantly accelerate the regeneration of bone tissue and peripheral nerve tissue, additionally, it improve healing process of wounds, especially ones like ulceration.Based on this, we extracted total Velvet Antler Polypeptides(VAP) from deer velvet antler and made a certain type of bone repair composite material tablets which possesses a mechanical strength for experiment.β-tricalcium phosphate is a scaffold in the composites which releases calcium and phosphate ions that could become the inorganic constituents of the new bone matrix implanted during degradation, or to become part of calcium and phosphorus pool of the body. In accordance with the experimental design, 84 2-month-old New Zealand white rabbits with body mass at about 2.0kg were selected and randomly divided into 7 groups of 12. Set: Material Group 1, Nanoβ-TCP/Gelatin/VAP (amount of VAP 5mg / g, cross-linked); materials group 2, Nanoβ-TCP/Gelatin/VAP (amount of VAP 5mg / g, no-crosslinked); materials group 3, Nanoβ-TCP/Gelatin/VAP (amount of VAP 20mg / g, cross-linked); material 4, Nano β-TCP/Gelatin/VAP (amount of VAP 20mg / g, no-crosslinked); material 5 groups, Nanoβ-TCP/Gelatin (cross-linked); Materials Group 6 , Nanoβ-TCP/Gelatin (no-crosslinked) and the control group. After implanting the materials and having set up the control group, according the schedule 2w, 4w, 8w, 12w to harvest the samples. Macroscopic observation, histological HE staining, VG staining, Goldner's trichrome staining observations, SEM analysis and Micro-CT analysis were made respectively. The observation and analysis of the results indicates that, Nanoβ-TCP/Gelatin/VAP (amount of VAP 5mg / g, cross-linked) of the composite materials (materials, group 1) performed the best in repairing the bone defects. The vast majority of defects were filled by the well structured new bone tissue in four weeks, and as time went by(4 to 8 weeks), the union between new bone tissue formed and the host bone became more obvious. Since VAP was not in Group 5 and Group 6, the new bone formation was only happening along the scaffold at a relatively slow speed. Due to lacking of mechanical support, the new bone formation in the control group was very slow. The results showed that the materials with an amount of VAP 5mg / g cross-linked (materials, group 1), performed best in promoting bone growth. The new bone formation is fast, stable, sustainable and efficient, and the rate of releasing VAP drug was properly controlled. Not only the half-life of the drug was extended, but also targeting of the drug can be achieved.This experiment examined the performance of the new nano-β-TCP / gelatin / polypeptide composites in repairing rabbit mandibular bone, and further clarified the effectiveness of VAP composite materials in promoting bone growth and a proper control in drug releasing rate. All evidence shows that this bone repair materials drug is capable of both medical treatment and rehabilitation. The bioactive factor (VAP) in the material fully composited with nano-materials, which endowed the materials with the loading and release function, extended the half-life of bioactive components degradation, improved bioavailability, promoted the function of bone formation continually, and eventually achieved an effective bone repair. This has laid a solid foundation for the promotion of composite materials in the human orthopedic surgery, dental implants and a variety of other services in health care activities.
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