| Bone defect is a common clinical condition. It often caused dysfunction and serious impacted on the patient’s physical and mental health. Autologous bone graft is the gold standard for the treatment of bone defects. However, its source is extremely limited. It is particularly troublesome for a large segment of bone defect. In recent years, the developing of tissue engineering brings hope to patients.At present, growth factors is often used as bone repairing inducer in the research of bone tissue engineering, but there were some shortcomings such as unstable, prone to inactivation, can not work for a long time. Icariin is the effective constituents of the traditional Chinese medicine epimedium. Numerous studies have demonstrated that Icariin can effectively promote the proliferation and differentiation of osteoblasts, has good bone-protective effect. Icariin has its unique advantage as bone tissueengineering-inducing factor.PHBV has good mechanical properties and biocompatibility, is an ideal bone tissue engineering scaffold material.In this study, first amino modified the icariin, then make it covalent with carboxymethyl Chitosan. PHBV, Chitosan as major raw materials, mixed them together,adding icariin in different forms, then fabricated the scaffold materials for bone repair by freeze-rapid prototyping. There are many advantages to the scaffold materials made for bone repair,such as high mechanical strength, simple making technology, inducer released with materials degrade gradually, solved some problems of engineering scaffold materials perfectly at present.The specific contents are as follows:(1) Modification of Icariin amino-modified Icariin by chemical method, then covalented carboxymethyl chitosan with icariin and then acquired the covalented materials. And the intermediate products and end products in these chemical reaction was detected.(2) Fabricate Chitosan/PHBV composite bone induction scaffold material Chitosan microspheres of icariin and icariin amination of Chitosan microspheres were prepared and detected. PHBV and Chitosan as raw materials, after double phases mixing, static settlement, extrusion molding, rapid freezing and freeze drying and other steps by different ways of drugs adding form then made of four kinds of scaffolds:blank control group,Ica-NH2 group, Ica-NH2-CSM group and Ica-CSM group. And evaluate the physico-chemical properties of the scaffold.(3) Evaluation of cytococompatibility Use rat bone marrow-derived mesenchymal stem cells(MSCs), to evaluate the cytococompatibility of the material.(4) Repair of bone defect repair the bone defect of 1.2 cm radius in rabbits by the four types of scaffold materials,1 month,3 month,6 month after operation, using Xray and three-dimensional CT imaging to observe the restoration area,and then HE, Masson, histological staining, to evaluate the effect of bone repair.Experimental results show that:(1) The amination of icariin FTIR show, in 1689, 3328, 3371cm-1 N-H characteristic peaks appeared, methylene characteristic peaks appeared at 2926, 2850 cm-1, indicating that amination of icariin is obtained.(2)The scaffolds were based on Chitosan and PHBV material, respectively add modified drugs covalently bonded materials or drug-loaded microspheres by different drug dosing patterns, then mixing preparation of scaffold for rapid freezing/freezedrying technique to obtain four groups of scaffolds.(3) The prepared microspheres of icariin and icariin amination microspheres are coated well.Ica-NH2 covalent scaffold group’s drug delivery volume reach the peak at 72 h, the other two scaffold materials’ drug delivery volume reach the peak at 48 h, IcaNH2 covalent group scaffold materials’ drug released slowly, short duration at the high concentrations, and is more suitable for drug delivery. The four scaffolds that constructed have good mechanical strength and biocompatibility.(4) Animal experiments show that scaffold for repair of the radius segmental defect of rabbits experimental x-rays and three-dimensional CT Imaging revealed, IcaNH2 Covalent group scaffold shows better bone repair effect than other materials: material surrounded by new bone formation, bone length became shorter, new bone formation appeared at the broken ends, and the scaffold material packed by the new bone tissue. Histological staining showed Ica-NH2 Covalent group induced osteogenesis ability is better than the other two groups of drug-loaded support material.In this research the four scaffold materials with good mechanical properties and biocompatibility, Covalent binding of the drug makes the scaffold to be able to effectively release icariin, promote the regeneration and repair of bone. |
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