Osteoporosis and ageing affects the migration of stem cells and this is ameliorated by transfection with CXCR4

OBJECTIVES: Cellular movement and relocalisation are important for many physiologic properties. Local mesenchymal stem cells (MSCs) from injured tissues and circulating MSCs aid in fracture healing. Cytokines and chemokines such as Stromal cell-derived factor 1(SDF-1) and its receptor chemokine receptor type 4 (CXCR4) play important roles in maintaining mobilisation, trafficking and homing of stem cells from bone marrow to the site of injury. We investigated the differences in migration of MSCs from the femurs of young, adult and ovariectomised (OVX) rats and the effect of CXCR4 over-expression on their migration. METHODS: MSCs from young, adult and OVX rats were put in a Boyden chamber to establish their migration towards SDF-1. This was compared with MSCs transfected with CXCR4, as well as MSCs differentiated to osteoblasts. RESULTS: MSCs from OVX rats migrate significantly (p < 0.05) less towards SDF-1 (9%, sd 5%) compared with MSCs from adult (15%, sd 3%) and young rats (25%, sd 4%). Cells transfected with CXCR4 migrated significantly more towards SDF-1 compared with non-transfected cells, irrespective of whether these cells were from OVX (26.5%, sd 4%), young (47%, sd 17%) or adult (21%, sd 4%) rats. Transfected MSCs differentiated to osteoblasts express CXCR4 but do not migrate towards SDF-1. CONCLUSIONS: MSC migration is impaired by age and osteoporosis in rats, and this may be associated with a significant reduction in bone formation in osteoporotic patients. The migration of stem cells can be ameliorated by upregulating CXCR4 levels which could possibly enhance fracture healing in osteoporotic patients