Gene expression profiles in murine hematopoietic stem cells revisited:: Analysis of cDNA libraries reveals high levels of translational and metabolic activities

Gene expression studies from hematopoietic stem cell (HSC) populations purified to variable degrees have defined a set of sternness genes. Unexpectedly, results also hinted toward a HSC chromatin poised in a wide-open state. With the aim of providing a robust tool for further studies into the molecular biology of HSCs, the studies herein describe the construction and comparative molecular analysis of A-phage cDNA libraries from highly purified HSCs that retained their long-term repopulating activities (long-term HSCs [LT-HSCs]) and from short-term repopulating HSCs that were largely depleted of these activities. Microarray analysis of the libraries confirmed the previous results but also revealed an unforeseen preferential expression of translation- and metabolism-associated genes in the LT-HSCs. Therefore, these data indicate that HSCs are quiescent only in regard of proliferative activities but are in a state of readiness to provide the metabolic and translational activities required after induction of proliferation and exit from the HSC pool.