Magnesium alloy transfected BMSCs-BMP-2 composite in repair of femoral head necrosis with assessment of visceral organs

BACKGROUND This study was designed to investigate the effect of BMSCs transfected BMP-2 composite with magnesium alloy rod in the repair of the femoral head necrosis in New Zealand white rabbits. Multifactorial but mostly traumatic, osteonecrosis of the femoral head account for 10 % of the 250,000 total hip arthroplasties done annually in the United States while its prevalence in most countries in not known. However, early intervention prior to collapse is critical to successful outcomes in joint preserving procedures. METHODS The pcDNA3.1 plasmid from cultured BMSCs was successfully transfected into BMSCs-BMP-2 by electroporation. Femoral head necrosis were established in 40 rabbits by liquid nitrogen freezing method. Animals were randomly divided into four groups (n = 10): Mg rod/BMSCs group, Mg rod group, BMSCs group, and blank control group. The composite of BMSCs-BMP-2 on Mg alloy rods were implanted respectively into the left femoral metaphysis of rabbits till the femoral head. Radiographic X-ray examination, histological hematoxilin and eosin (H&E) analysis and immunohistochemistry techniques were performed postoperatively; to observe and compare by the schedule; the newly formed bone and the degradation of the Mg rod at 6 and 12 weeks, sacrificing five animals at each time. RESULTS Twelfth week histological and immunohistochemical examinations showed complete magnesium alloy absorption in experimental and control group. H&E staining and immunohistochemistry showed obvious differences, Mg rod/BMSCs group having the best recovery than the other groups. BPM-2 level of gene expression of experimental group was also higher than those of controlled group. CONCLUSION BMP-2 coated Mg alloy promotes the expression of bone growth factors at the implant in marrow of rabbits thus delaying femoral head necrosis and improving repair.