The objective of the proposed research is to identify factors within the microenvironment of injured tissue that may enhance stem-cell plasticity across germ layers, using an in vitro co-culture of human bone marrow stromal cells (MSC) and human bronchial epithelial cells (BEC) as a model system. The overall hypothesis is that MSC plasticity is influenced by the extent of BEC differentiation, severity of injury, and delay time between injury and repair with MSC. In testing this hypothesis the investigators propose 2 specific aims: aim 1 tests the hypothesis that MSC will acquire an epithelial phenotype, as assessed by polarity, tight cell contacts, gene expression profile, morphology and mucosa production, when co-cultured in vitro with heat-shocked BEC in a regenerated bronchial epithelium more profoundly than in a poorly differentiated monolayer, and aim 2 tests the hypothesis that (1) epithelial differentiation of MSC can be induced in vitro by an alternative mode of BEC injury - - bleomycin exposure, and (2) the extent of MSC differentiation is dependent on the severity of BEC injury and delay time between injury and addition of MSC to culture.
