An Aged Bone Marrow Niche Restrains Rejuvenated Hematopoietic Stem Cells. (13th April 2021) - Guidi, Novella
Abstract: Aging-associated leukemia and aging-associated immune remodeling are in part caused by aging of hematopoietic stem cells (HSCs). An increase in the activity of the small RhoGTPase cell division control protein 42 (Cdc42) within HSCs causes aging of HSCs. Old HSCs, treated ex vivo with a specific inhibitor of Cdc42 activity termed CASIN, stay rejuvenated upon transplantation into young recipients. We determined in this study the influence of an aged niche on the function of ex vivo rejuvenated old HSCs, as the relative contribution of HSCs intrinsic mechanisms vs extrinsic mechanisms (niche) for aging of HSCs still remain unknown. Our results show that an aged niche restrains the function of ex vivo rejuvenated HSCs, which is at least in part linked to a low level of the cytokine osteopontin found in aged niches. The data imply that sustainable rejuvenation of the function of aged HSCs in vivo will need to address the influence of an aged niche on rejuvenated HSCs. Abstract : Model of the influence of the niche on old rejuvenated hematopoietic stem cells (HSCs). Old HSCs can be rejuvenated by Cdc42 activity inhibition, and maintain this youthful function when transplanted in young niches. In contrast, when they encounter an aged niche, they are reverted, at least in part, to old HSCs. This revertion might be due to reduced osteopontin level in aged niches.