Skin renews despite 60% to 70% fibroblast depletion in mice, challenging long-held assumption (opens in new tab)

Human skin is constantly rebuilding itself. Every few weeks, the outermost layers shed and are replaced by new cells pushed up from the base. For decades, scientists believed this renewal depended heavily on fibroblasts, a class of supportive cells nestled in the deeper layer of the skin that secrete growth-promoting molecules and build the structural scaffolding that holds tissue together.