Aberrant engagement of P-selectin drives hematopoietic stem cell aging in mice.

During aging, hematopoietic stem cell (HSC) function progressively declines which can lead to reduced blood cell production and regeneration. This work uncovered that cell surface presentation of P-selectin (CD62P, encoded by Selp) increases in a large fraction of aging HSCs driven by a proinflammatory milieu in mice. Notably, expression of P-selectin molecularly and functionally dichotomized the aging HSC pool; stem cells presenting with highly abundant P-selectin were hallmarked by aging-associated gene expression programs and reduced repopulation capacity upon regenerative stress. Ectopic expression of Selp in young HSCs was sufficient to impair long-term reconstitution potential and impair erythropoiesis. Mechanistically, we uncovered that P-selectin receptor activation by its primary ligand, P-selectin glycoprotein ligand-1, suppressed aging-associated gene expression, and, reversely, lack of P-selectin signaling led to HSC premature aging. Collectively, our study uncovered a functional role of P-selectin engagement in regulating HSC regeneration and driving stem cell aging when perturbed.