
A trifling paper cut is a site of frenzied activity. Within it, a squad of epidermal stem cells briskly regenerate to patch up the wound. A closer inspection of this war-torn swath of epidermis will reveal that, while some of the stem cells are native to the area, others are newcomers--former hair-producing stem cells that, upon sensing nearby injury, migrated from the hair follicle to the wound bed, where they transformed to resemble indigenous epidermal stem cells. Now, a new study demonstrates that, within their genetic material, these relocated stem cells retain memories of how to travel from the follicle to the skin’s surface, repair damaged skin, and finally adapt to their new home. These seasoned stem cells are largely indistinguishable from naive epidermal stem cells. But the new research, published in the November 26, 2021 issue of Science, suggests that they are primed to heal wounds faster and, after repeated wounds, may develop memories that could lead to chronic disease and cancer. The article is titled “Stem Cells Expand Potency and Alter Tissue Fitness by Accumulating Diverse Epigenetic Memories.”