Transcriptional reprogramming of skeletal muscle stem cells by the niche environment

Abstract Adult stem cells are indispensable for tissue regeneration, but the number and regenerative capacity of stem cells declines with age. Whether the decrease in stem cell function is the cause or consequence of the aging of a tissue is unclear. Evidence suggests that the niche environment plays a critical role in the regulation of adult stem cell function6-10. However, quantification of the niche effect on stem cell function is an unmet challenge. Using muscle stem cells (MuSCs) as a model, we show that aging leads to a significant transcriptomic shift in MuSC subpopulations. By combining in vivo MuSC transplantation, multi-omics and computational methods, we show that the expression of approximately half of all age-altered genes in MuSCs can be restored by exposure to a young niche environment. Age-related genes whose expression is not restored exhibit altered chromatin accessibility and are associated with differentially methylated regions between young and aged cells. Our findings establish that the expression of the majority of age-related altered genes that are not epigenetically encoded is readily restorable by exposure to a young niche environment. The stem cell niche may therefore be an important therapeutic target to mitigate the negative consequences of aging on tissue regeneration.