Therapeutic effect of osteogenically induced adipose derived stem cells on vascular deprivation-induced osteonecrosis of the femoral head in rabbits.

OBJECTIVE: To explore the therapeutic effect of osteogenically induced adipose-derived stem cells (ADSCs) on vascular deprivation-induced osteonecrosis of the femoral head (ONFH) in rabbit model.

METHODS: Vascular deprivation-induced ONFH was established by intramuscular injection of methylpre- dnisolone, and vascular occlusion of the capital femoral epiphysis by electrocoagulation in adult New Zealand white rabbits. Eight weeks after the establishment of vascular deprivation-induced ONFH, animals were randomly divided into three equal groups. In Group A (control), no therapy was given. In Group B, core decompression was performed by drilling a hole (1.2 mm in diameter) from the outer cortex 2.5 cm distal to the proximal end of the greater trochanter. In Group C, 1 multiply 10(7) osteogenically induced ADSCs were resuspended in 0.5 ml PBS, and then injected directly into the femoral head. Femoral head specimens were obtained at postoperative 8 weeks. The bone formation and three-dimensional microstructure of the femoral head was evaluated by micro-computed tomography scans. Immunohistochemical analysis was performed to detect the expression of osteocalcin. Angiogenesis and repair of the femoral head were observed histologically.

RESULTS: In trabecular bone at the proximal femur region, the trabecular volume was higher in Group C (130.70 mm(3)+/-4.33 mm(3)) than that in Groups A (101.07 mm(3)+/-7.76 mm(3)) and B (107.89 mm(3)+/-8.68 mm(3), P less than 0.01). Bone volume was significantly increased in Group C (40.09 mm(3)+/-6.35 mm(3)) than in Groups A (29.65 mm(3)+/-4.61 mm(3)) and B (31.80 mm(3)+/-4.01 mm(3), P less than 0.01). The trabecular number was higher in Groups C (1.58+/-0.25) than other two groups (1.15+/-0.18, 1.16+/-0.21, P less than 0.01). Bone mineral density showed statistically significant difference between Groups C and A or B (375.38+/-23.06) mg HA/ccm, vs (313.73+/-19.30) mg HA/ccm and (316.09+/-16.45) mg HA/ccm, P less than 0.01). Histological examination indicated that there was more new bone formation in Group C than in other groups.

CONCLUSION: Treatment with autologous osteogeni-cally induced ADSCs transplantation results in an enhanced osteogenesis and microstructure of the vascular deprivation-induced osteonecrosis in rabbits.