Directing mesenchymal stem cells to bone to augment bone formation and increase bone mass

Targeting mesenchymal stem cells (MSCs), progenitors of osteoblasts, to bone has been a long-standing goal but has had limited success so far. Here, Min Guan and her colleagues deliver a peptidomimetic integrin ligand against integrin α4β1 conjugated to the bone-seeking agent bisphosphonate alendronate as a means of attracting infused and/or endogenous MSCs to the bone surface to stimulate bone formation. The approach was tested in both xenotransplantation and immunocompetent mice, as well as in mouse models of trabecular bone loss induced by aging and estrogen deficiency (ovariectomy).