Adipose-derived stem cells enhance bone regeneration in vascular necrosis of the femoral head in the rabbit

Osteonecrosis of the femoral head was induced in rabbits by intramuscular injection of methylprednisolone and vascular occlusion of the capital femoral epiphysis by electrocoagulation. Eight weeks later the animals received no treatment (group A), core decompression by drilling a hole (diameter 1.2 mm) from the outer cortex 2.5 cm distal to the proximal end of the greater trochanter (group B), or injection of 10(7) autologous adipose-derived stem cells (ADSCs) directly into the femoral head (group C). Eight weeks later, microcomputed tomography scans indicated that bone and trabecular volume and density were significantly higher in group C than in other groups. Histology indicated more new bone formation in group C than in other groups. Group C showed strong osteocalcin immunoreactivity in subchondral bone osteoblasts in the necrotic femoral head, whereas few osteocalcin-positive cells were found among osteoblasts in other groups. Thus, autologous ADSC transplantation improved osteogenesis and the microstructure of vascular deprivation-induced osteonecrotic tissue.