Decreased osteogenic differentiation of mesenchymal stem cells and reduced bone mineral density in patients with adolescent idiopathic scoliosis

Generalized low bone mass and osteopenia in both axial and peripheral skeletons have been reported in adolescent idiopathic scoliosis (AIS). However, the mechanism and causes of bone loss in AIS have not been identified. Therefore, this study examined the relationship between the osteogenic and adipogenic differentiation abilities of mesenchymal stem cells (MSCs) and bone mass in 19 patients with AIS and compared these with those of 16 age- and gender-matched patients with lower leg fracture. Mean lumbar spinal bone mineral density (LSBMD) in AIS patients was found to be lower than in controls (P = 0.037) and the osteogenic differentiation abilities and alkaline phosphatase activities of MSCs from patients were also found to be lower than those of controls (P = 0.0073 and P = 0.001, respectively), but the abilities of the MSCs of patients and controls to undergo adipogenic differentiation were similar. The osteogenic differentiation ability was found to be positively correlated with alkaline phosphatase activity in the AIS group. However, the osteogenic and adipogenic abilities were not found to be correlated with LSBMD in either patients or controls. These findings suggest that the decreased osteogenic differentiation ability of MSCs might be one of the possible mechanisms leading to low bone mass in AIS. However, we did not determine definite mechanisms of low bone mass in AIS. Therefore, further study with large scale will be needed to identify the mechanism involved.