Prevention of corticosteroid-induced osteonecrosis in rabbits by intra-bone marrow injection of autologous bone marrow cells

Objectives. Femoral head osteonecrosis (ON) is a serious complication of steroid administration. We evaluated bone marrow transplantation (BMT) for preventing corticosteroid-induced ON. Methods. Rabbits, injected with methylprednisolone (MPSL; 20 mg/kg), were divided into four groups: (i) MPSL alone; MPSL injection only, (ii) MPSL + needling; 2 days after MPSL injection, a hole (1.2 mm diameter) was drilled from the outer cortex 2.5 cm distal to the proximal end of the greater trochanter, (iii) MPSL+saline; 2 days after MPSL injection, 2 ml saline was injected directly into the bone marrow cavity, and (iv) MPSL+BMT; 2 days after MPSL injection, 1 x 10(7)/2 ml bone marrow cells (BMCs) were injected directly into the bone marrow cavity. Platelets, fibrinogen, prothrombin time and total cholesterol in peripheral blood were measured before and after treatment. Tissues were stained with haematoxylin and eosion and terminal deoxynucleotidyl-mediated deoxyuridine triphosphate nick-end labelling stain and immunostained for VEGF, while cell proliferation and viability of whole BMCs in the femur were analysed by cell cycle analysis and [H-3]-thymidine uptake. Results. The ON incidence in rabbits treated with MPSL alone, MPSL+needling and MPSL+saline was 72.7, 70.0 and 66.7, respectively, while in the MPSL+BMT group, the incidence was 0. Serological findings in the MPSL+BMT group were almost normalized. VEGF and TUNEL staining were reduced in the MPSL+BMT group compared with all other groups. There were significantly fewer BMCs in G1 phase from the MPSL+BMT group than the other groups, while uptake of [H-3]-thymidine was significantly increased. Conclusion. Direct injection of autologous BMCs into femurs prevents corticosteroid-induced ON following treatment with high-dose, short-term steroids.