Injectable Bone Repair Materials Combine Osteopractic Total Flavone Repair Rat Bone Defect

IntroductionBased on the fact that the accidents rate of bone nonunions, bone defects are approximately 5-10%, the repair of critical-sized bone defects is a challeging problem around the world.The autogenous bone graft, which is with limited resource, has been deemed as the golden criterion in bone repair for its osteoconductivity and osteoinductivity. And it is known to all that the xenogeneic bone or allogenic bone would cause immunological rejections which limite their application in bone repair. The Department of Materials Science and Engineering of Tsinghua University has designed a nanoporous material according to biomimetic method. Based on the template of tropocollagen molecule, a bone-like nano-hydroxyapatite/collagen (nHAC) composite was synthesized biomimetically by the orderly deposition of hydroxyapatite mineral with low crystallinity, hierarchical structure. It has a good biocompatibility and biodegradability. Recentaly, we have developed an injectable bone regeneration composite (IBRC) by using a calcium alginate hydrogel as matirx vehicle. It has good potential application in future for it not only maintained the natural bone-like characterics of nHAC but also a good injectability.The Chinese medicine drynaria fortunei (DR) has many therapeutic functions, such as strenthening tendons and bones, invigorating the kindey and spermium, as well as pain and bruises relieving. It has been vertified by the contemporary pharmacological studies that assemble flavone of rhizome drynaria (AFDR) can promote fracture repair, and improve microcirulation, treat the osteoporosis, as well as certain anti-inflamatory and analgesic effects. The bone growth factor BMP2, which plays a crucial role in fracture healing and bone remodling, has been used for fracture healing and bone defect treatment successfully.Combine the IBRC with AFDR or BMP2 in the application of bone defect repair may reduce the trauma response and improve the repair quality. It has been an exploration mode of combination of Chinese and western medicine for bone defects treatment.ObjectiveThis article discusses the mode of combing Chinese and western medicine in bone defects repair, which is based on observasion and comparative studies of the effect by the application of IBRC in combination with AFDR or BMP2.Methods1) andomized controlled trials. Arranged 80 SD rats into three groups, and made a control test with a 5mm diameter wide calvarial defects on the right side and the left skull defects as comparison. Group A (IBRC+AFDR, n=30):Implanted IBRC to the bone skull defect and fed the rats with AFDR for 2-8 weeks. Groud B(IBRC+DW,n=30):Implanted IBRC to the skull defect on the right, fed the rats with DW for 2-8 weeks. Group C (IBRC-HA+DW, n=20):Implanted IBRC-HA to the skull defect on the right, fed the rats with DW for 2-8 weeks. Executed the rats on week 2,4 and 8, and drawn the blood in the abdominal arteriae aorta for the test of serum calcium, phosphorus, alkaline phosphatase, creatinine, and alanine aminotransferase. Inbedded the skull specimens with paraffin and sliced, and observed the changes of the tissues after HE and Masson stained. After alkaline phosphatase and type I collagen immunohistochemical staining, as well as BMP2 in situ hybridization, we observed the microsope image and analyzed the OD value, and the index was analyzed by statistic treatment.2) Randomized controlled trials:40 rats were randomly arranged into 4 groups and made critical-sized calvairal defects with 8mm diameter wide. Group A (IBRC+AFDR, n=12): Implanted IBRC on the defects, and fed the rats with AFDR for 2-8 weeks; Group B (IBRC+DW, n=12):Implanted IBRC and fed the rats for 2-8 weeks; Group C (IBRC+rhBMP2.n=13):Implanted the combination of IBRC and rhBMP2 (15ug/ml); Group D (n=3); No implant. Removed calvairal bones from the rats at week 2,4,6,8,12 and examined them with Micro-CT and HE stainning for repair effect evaluationResultsIn the experiment of skull bone defects repair by the combination of IBRC and AFDR, there wasn't any change of the value of serum calcium, phosphorus or calcium phoshate on week 2. But a significant raise (P< 0.05) was found in the control group on week 4. The result remained the same on week 4 and 8, but the creatinine has siginficantly decreased (P<0.05) in the AFDR group in the comparision with DW group on week 8. The repair effects in histological observation:Repair effect of the IBRC+AFDR group is better than the IBRC+DW group's, HA group is the worst one of the three. It is showed in the type I collagen immunohistochemical stained and the analysis of the BMP2 ISH graphics that the positive expression of the IBRC+AFDR group is much obvious than the other two. In the experiment of critical-sized calvarial defects, the repair effect of IBRC+rhBMP2 was the best, and the IBRC+AFDR group is better than the IBRC+DW group. Conclusion1) In the experiment of combining AFDR and IBRC for calvarial defect repair, alkaline phosphatase has significantly improved in two weeks, and the amount of calcium in blood, phosphorus and calcium phosphate product level is higher in four weeks. All of these have proved that AFDR has the effect on promoting bone repair.2) The repair time can be shorten and the quality can be improved when defects are repaired by IBRC in the combination with AFDR.3) The positive expression of BMP2 can be improved and sequentially boost the osteoinductivity of the material when defects are repaired by the combination of IBRC and AFDR.4) It can improve the positive expression of Coll-I and ALP, facilitating the formation and mineralization of bone matrix when the bone defects are repaired by the combination of IBRC and AFDR.5) The observation method of this experiment of IBRC bone defects repair is based on the endochondral bone formation.6) IBRC can be used in the critical-sized bone defect on rats, and with the combination of AFDR can distinctly raise the speed and quality of repairment, however, its effect is not as good as the combination of IBRC and BMP2.7) The effect of IBRC and AFDR combination for bone defects are not as good as the combination of IBRC and BMP2, which also verify the effetivity of rhBMP2. At the same time, it also challenges the effectiveness of Chinese medicine for promoting bone repair. Since the traditional Chinese medicine treatment has been focused on compoud medicine, it is necessary to carry out an in-depth research on compound medicine.8) There is no hepatorenal toxicity symdrome after feeding the rats with conversed dose of AFDR for 8 weeks. And it may increase the function of glomerular filtration.