【Abstract】 Objective To investigate both incidence and mechanism attributing to steroid-associated osteonecrosisof femoral head(ONFH) using an experimental protocol with a single low-dose l i popolysaccharide (LPS) injection andsubsequently three injections of high-dose methylprednisolone (MPS). Methods Twenty-five New Zealand white rabbits with body weight of (3.0 ± 0.3) kg were divided randomly into 2 groups. In treatment group, 19 rabbits received one intravenous injection of LPS (10 μg/kg); 24 hours later, three injections of 20 mg/kg of MPS were given intramuscularly at an interval of 24 hours. Additional 6 rabbits which received normal sal ine injection at the same time point were used as controls(control group). The blood samples were collected for hematological examinations before and after LPS injection, MRI was performed on bilateral hip six weeks after last MPS injection, meanwhile, bone marrow was aspirated from femoral head region to evaluate stem cell’s activity. Bilateral femoral heads were harvested to make histopathology examination. Results All animals survived throughout the experiment period except one death on the second day after LPS injection. In the histopathological examinationfor the femoral head, ONFH+ was observed in 16 rabbits (88.9%), and the lesions were mainly in the metaphysis. In ONFH+ rabbits, micro vessels fibrous thrombosis and extravascular marrow fat cell size increasing were found around necrotic bone; The femoral heads of control group had no changes. MRI accurate ratio was 93.8% (15/16). Compared to basel ine, a significant decrease in ratio of tissue plasminogen activator/plasminogen activator inhibitor 1 and activated partial thromboplatin time, and a significant increase in ratio of low-density l ipoprotein/high-density l ipoprotein were only found in ONFH+ rabbits (P lt; 0.05). Meanwhile there was a significant decrease in the number of CFU-F (8.50 ± 9.63) compared with the control (70.17 ± 7.78, P lt; 0.05). Conclusion A single low-dose LPS injection and subsequent three injections of high-dose MPS is effective on building steroid-associated ONFH model, coagulation and l ipometabol ism abnormal ity, activity degeneration of stem cell may be the key factors of ONFH.
【Abstract】 Objective To approach the possibil ity of combination of simvastatin and BMSCs transplantation forsteroid-associated osteonecrosis of femoral head. Methods The BMSCs harvested from 24 rabbits were prepared for cell suspension at a concentration of 1 × 107/mL, and combined with gelatin sponge. Seventy New Zealand white rabbits received one intravenous injection of l ipopolysaccharide (10 μg/ kg). After 24 hours, three injections of 20 mg/kg of methylprednisolone were given intramuscularly at a time interval of 24 hours. Forty-eight rabbits diagnosed as having femoral head necrosis by MRI were divided into 4 groups randomly, group A: no treatment; group B: only decompression; group C: decompression and BMSCs transplantation; and group D: simvastatin drench (10 mg/kg.d) decompression and BMSCs transplantation. The general information of animals were recorded; after 4 and 8 weeks of operation, 6 rabbits of each group were chosen randomly to do MRI scan, and femoral heads were harvested to do histopathology and scanning electron microscope examination. Results After 8 weeks, rabbits became more active than before treatment, and walking way became normal gradually in groups C and D. Fourweeks after operation, the MRI low signal region of all groups had no obvious changes, but 8 weeks later, the necrosis signal region of group A magnified while it reduced obviously in group D. Histopathological observation: 4 weeks after operation, diffuse presence of empty lacunae and pyknotic nuclei of osteocytes were found in the trabeculae, and few newborn micrangium could been seen in group A; lots of empty lacunae and a small quantity of newborn micrangium could been found in group B; and large amounts of osteoblats and newborn micrangium were found around the necrosis regions in groups C and D. The positive ratio of empty lacunae and microvessel density in group D were 19.30 ± 1.52 and 7.08 ± 1.09, showing significant difference compared with other groups (P lt; 0.05). After 8 weeks of treatment, the bone trabecula collapsed in many regions in group A; there was fibra callus formation along the decompression channel in group B; few empty lacunae was in the bone trabecular, but the shape of marrow cavity was not normal in group C; and it showed almost normal appearance in group D. The positive ratio of empty lacunae and microvessel density in group D were 11.31 ± 1.28 and 12.37 ± 1.32, showing significant differences compared with other groups (P lt; 0.05), meanwhile, showing significant difference compared with that of 4 weeks after operation(P lt; 0.05). Scanning electron microscope: 8 weeks after operation, the bone trabecula collapsed in many regions, and few osteoblasts could be found on the surface, a great quantity of fat cells cumulated in the bone marrow in group A; cracked bone trabecula could be found occasionally in group B; the density of bone trabecula was lower than the normal in group C; and the shape of the marrow avity and thedensity of bone trabecula were similar to the normal in group D. Conclusion Simvastatin can promote the differentiation of osteocyte and vascular endothel ial cell from MSCs, the combination of simvastatin and marrow stem cells transplantation for the treatment of steroid-associated osteonecrosis of femoral head have good appl ication prospects.