Hypoxia enhances neurosphere formation in bone marrow stromal cells via epidermal growth factor receptor signaling

Abstract

Neural stem / progenitor cells form neurospheres when cultured in-vitro. A subpopulation of bone marrow stromal cells are able to form neurospheres as well as differentiate into neurons and glia, making them an attractive source for autologous cell therapy. An understanding of what regulates the propensity for sphere formation, as well as the differentiation potential of these cells, will enable one to enhance the yield and potency of neurospheres obtained from donor tissue. In this study, we demonstrate that hypoxia-mediated enhancement of epidermal growth factor receptor (EGFR) signaling is a mechanism by which neurosphere formation is increased. Hypoxia (5% O 2 ) leads to an upregulation in EGFR protein expression in bone marrow stromal cells, and subsequently an increase in the size and number of neurospheres as compared to normoxia controls. Subsequent to this, cells demonstrate an increased sensitivity to exogenous EGF. These effects are attenuated with the use of the EGFR inhibitor Erlotinib. Importantly, hypoxia did not affect the multipotency of the neurospheres, as evidenced by their ability to form cells of neuronal and glial lineages. These data suggests that targeting the EGFR pathway is an approach to enriching for neurosphere formation from patient tissue.