Regenerative effects of transplanting autologous mesenchymal stem cells on corticosteroid-induced osteonecrosis in rabbits.

Osteonecrosis (ON) of the femoral head is one of the most serious complications associated with steroid administration. Here, we treated corticosteroid-induced ON in the rabbit by transplanting mesenchymal cells (MCs). Rabbits were injected once with 20 mg/kg of methylprednisolone (MPSL) and divided into three groups as follows: (1) MPSL alone (no further treatment); (2) MPSL+MCs (7 days after MPSL, MCs [1 x 10(7)/2 ml] were injected into the bone marrow cavity of the femurs); (3) MPSL+saline (7 days after MPSL, saline [2 ml] was injected into the bone marrow cavity of the femurs). Subsequently, the incidence of ON in the femurs 4 weeks after MPSL alone and MPSL+saline was 80 and 68.4%, respectively. In contrast, no ON was recorded in rabbits treated with MPSL+MCs. Vascular endothelial growth factor (VEGF) staining and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick end-labeling (TUNEL) staining was more marked in the MPSL alone and MPSL+saline groups than in the MPSL+MCs rabbits. The percentages of cells in the G1 phase in the MPSL+MCs group were significantly lower than in the other two groups. These findings suggest that the injection of autologous MCs into the femur could prevent corticosteroid-induced ON in patients treated with high-dose short-term steroid medication.