AbstractObjectiveSecondary alveolar bone grafting is an essential part in the treatment of alveolar cleft deformity. Autologous iliac bone is the most favorable grafting source. However, the factors regulating postoperative bone formation are unclear. Investigations are needed to found whether the alveolar bone niche and bone marrow mesenchymal stem cells (BMSCs) derived from the jaw bone (BMSCs‐J) affected the osteogenesis of BMSCs from the ilium (BMSCs‐I).Materials and MethodsThe effect of BMSCs‐J on BMSCs‐I was investigated using a co‐culture model. The exosomes were purified by sequential centrifugation. The osteoblastic differentiation of BMSCs was analyzed in vitro and in vivo.ResultsCo‐culture with BMSCs‐J increased the alkaline phosphatase (ALP) activity, Alizarin Red S (ARS) staining, and osteogenic gene expression in BMSCs‐I. Transmission electron microscopy and nanoparticle tracking analysis verified the presence of exosomes in the culture supernatants of BMSCs. Exosomes secreted by BMSCs‐J enhanced the ALP activity, ARS staining, osteogenic gene expression of BMSCs‐I in vitro, and new bone formation in vivo. Blocking the secretion of exosomes using siRNA for Rab27a inhibited the effect of BMSCs‐J.ConclusionExosomes played a role in the interaction between BMSCs‐J and BMSCs‐I, thereby leading to the enhanced osteogenic capacity of BMSCs‐I and bone formation.