The Effect Of Fibronectin And Sonic Hedgehog And Bone Morphogenic Protein-2 Combined With Nano-Hydroxyapatite/Collagen For The Repair Of Rat Femoral Bone Defects

Objective:To study the effect of Fibronectin(FN) and sonic hedgehog(shh) and bone morphogenic protein-2(BMP-2) combined with the compound of marrow mesenchymal stem cells (MSCs) and nano-hydroxyapatite/collagen(nHAC) bone on the treatment of rat femoral bone defects.Methods:MSCsobtained from SD rat bone marrow were cultured in four groups:control group:common nHAC;Group A: nHAC modified with BMP-2 and shh;Group B:nHAC modified with BMP-2 and FN;Group C:nHAC modified with FN and BMP-2.At different time points(3,6,9,12d),the numbers of cells proliferate were counted and the levels of alkaline phosphatase(ALP) activity were detected.The expression of osteoblastic phenotypes were demonstrated and collagen typeⅠimmunoblot were analyzed.Animal models of femoral bone defect were established in 30 Sprague-Dawley rats.They were divided into 3 groups randomly:Group a:the control group, defect was filled with nHAC;Group b:with nHAC/MSCs;Group C:BMP-2/FN/MSCs/nHAC.Environment scanning electron microscope(ESEM) observation was made 12 weeks after operation. Imaging and histological observation were made 3,6,9,12 weeks after operation.Results:After differentiation of MSCs obtained from SD.The osteoblast morphological characteristics,the osteoblastic phenotypes and collagen typeⅠprotein expresssion were changed at each groups,and the group C was most obvious being observed;The cell numbers and the expression of the ALP increased with cultivating time for the four groups and group C were most obvious being demonstrated.At the same time point compared group C with other groups,the difference had statistical significance(P＜0.05) All of 30 rats were involved in the result analysis.①No inflammation or rejection response was detectable during the experiment,and the wound healed well.②There were significant differences in bone regeneration between group C and the other groups in 3, 6,9 and 12 weeks after operation(P＜0.01).③Histomorphology test showed that group c had better osteogenesis ability than group b and group a;Group b had better osteogenesis ability than group a.Conclusions:The bone defect repair ability of tissue—engineering bone which constructed with FN/BMP-2/MSCs/nHAC is stronger than nHAC combined with MSCs or nHAC alone.It can well repair segmental bone defects,and is promising to be new implant material in bone tissue engineering.