Polymeric Skin Booster with Moderate Collagen Regeneration

Abstract In recent years, medical aesthetics develops an intracutaneous injection of a polymer like hyaluronic acid (HA) to improve skin appearance tentatively. But an ideal skin booster may, besides transient filling of dermis, stimulate collagen regeneration. Herein, inspired by the finding reported in the literature that lactic acid (LA) stimulates fibroblasts to secret collagen in vitro, an LA‐releasing block copolymer composed of biodegradable poly(lactide‐ co ‐glycolide) and poly(ethylene glycol) is introduced. The aqueous system of this copolymer undergoes sol‐gel transition upon heating, and it is found that the sol can even be injected with microneedles of the thinnest hole (34 G). After injection, a physical hydrogel forms spontaneously; the thermogel (T‐gel) releases LA owing to polymer biodegradation over weeks. The LA activates fibroblasts through transforming growth factor‐β/Smads signaling pathway, stimulating balanced synthesis of collagen I and III, resulting in tissue remodeling that is less extensive than typical dermal scarring. Preclinical study in the photoaged model demonstrates significant improvements in skin smoothness and collagen density, confirming the capacity of T‐gel to rejuvenate skin appearance. This work affords a strategy to employ biomaterial degradation to generate a collagen stimulator in an appropriate extent and achieve sustained skin rejuvenation.