Deficient or inappropriate healing of bone impacts clinical decision-making and treatment options in orthopedics, oral and maxillofacial surgery, plastic surgery and periodontics. While a number of auto- and allografting techniques have been used to regenerate craniofacial defects caused by infective, neoplastic or trauma-induced bone loss, each method has significant limitations. Our research group in the Craniofacial and Skeletal Diseases Branch of NIDCR has developed methods to culture and expand cell populations derived from mouse bone marrow stroma. We believe that an important next step is to apply the information gained in animal studies to treat osseous defects in humans. We propose to examine the potential of cultured human bone marrow stromal cells to serve as an abundant source of osteoblastic progenitor cells. These cells will ultimately be used to graft craniofacial osseous defects. In the course of this study we will: (1) develop methods for the propagation and enrichment of osteoblastic progenitor cells from bone marrow stroma; (2) test various vehicles for the transfer of bone marrow stromal cells to osseous defects in recipient animals; (3) determine optimal culturing and transplantation conditions for the eventual transplantation of bone marrow stromal cells into human recipients. These studies will define the parameters of bone marrow stromal cell transplantation and will generate models for future therapeutic strategies.