The Effectiveness of Bone Mineral Density as Supplementary Tool for Evaluation of the Osteogenic Potential in Patients with Spinal Fusion

STUDY DESIGN: Retrospective study. PURPOSE: This study was designed to determine the effectiveness of bone mineral density measurement as a supplementary tool for evaluation of osteogenic potential in patients with spinal fusion. To this end, we correlated bone mineral density (BMD) with osteogenic potential from cultured mesenchymal stem cells (MSCs). OVERVIEW OF LITERATURE: Many studies have correlated osteogenic potential of in vitro cultured MSCs with aging or osteoporosis. METHODS: We studied twenty-five individuals with harvested bone marrow from the ilium during lumbar spinal surgery. The BMD of the femoral neck was measured using dual energy X-ray absorptiometry prior to bone marrow aspiration, and the osteoporotic group was classified as those with T-scores below-2.5. After MSCs were isolated from bone marrow, in vitro induction of osteogenesis was performed. We analyzed the patient's osteogenic potential from cultured MSCs such as mineral deposition stain, bone alkaline phosphatase (ALP) activity and osteoblast-specific gene expression in RT-PCR. RESULTS: On mineral staining, the osteoporotic group had a scanty matrix mineral deposition in contrast to the non-osteoporotic group. The expression of osteocalcin in the osteoporotic group was 1.5 to 3 times less than in the non-osteoporotic group. At the 3(rd) week after the induction of osteogenesis, the activity of ALP of cultured MSCs in the osteoporotic group was lower than in the control group (mean, 45+/-19 u/L, in osteoporotic group vs 136+/-7 u/L in non-osteoporotic), and there was a statistically significant and positive correlation between BMD & ALP (r=0.487, p=0.013). CONCLUSIONS: There is a positive correlation between BMD and osteogenic potential derived from MSCs. The measurement of BMD can provide supplementary data for evaluating osteogenic potential clinically.