The overall aim of this proposal is to establish a Center for preparation, quality testing, and distribution to multiple investigators of the adult stem cells referred to as MSCs. The cells have attracted increasing attention because they are readily isolated from the patient, expanded in culture, and genetically engineered. They can differentiate into multiple cell lineages and have recently reported to have some efficacy in animal models for diseases such as osteogenesis imperfecta, spinal cord injury, stroke, and cardiomyopathies. The Center will address a critical problem that has delayed research with MSCs; the difficulties that many investigators have encountered in obtaining standardized preparations of the cells. The urgent need for a Center of the kind proposed here is reflected by the fact that 84 other investigators have provided Letters of Support for the present application. The list includes essentially all the leading investigators in this rapidly growing field. The Specific Aims are to establish a Center that will: 1) prepare a continuous supply of human MSCs that are thoroughly quality tested and distribute them on request to other investigators at multiple institutions for research on the cells; 2) prepare a similar continuous supply of rat MSCs for distribution to investigators at multiple institutions; 3) prepare MSCs from human bone marrow aspirates sent by investigators from other institutions and return the quality-tested MSCs to same investigators. Also, carry out quality testing of MSCs prepared by investigators at other institutions; and 4) develop improved methods of isolating and characterizing human MSCs using the antibodies to a series of surface epitopes that have recently been identified on the cells.