Background: It is now apparent that virtually every human post-natal tissue contains some type of stem/progenitor cell population that is responsible for tissue turnover and repair. Our previous studies have identified a subset of human bone marrow stromal cells (BMSCs) that is multi-potent and able to regenerate bone, cartilage, myelosupportive stroma and adipocytes, whereas stromal cells derived from human spleen (SpSCs) and thymus (TSCs) only form myelosupportive stroma. Recent studies suggest that human adipose-derived stromal cells (ASCs) may be similar to BMSCs, whereas stromal cells derived from human dermis (DSCs) have none of these properties (and serve as a negative control for most experiments in vitro and in vivo). How similar or dissimilar these different stromal cell populations are has yet to be determined. Molecular profiling is needed to compare these different populations and in order to elucidate the factors that control differentiation stromal cells into one cell type or another.