Biodegradable PLLA/PLGA microspheres/collagen composites for continuous soft tissue augmentation

Skin aging is caused by a combination of endogenous and exogenous factors. The dryness, roughness, and pigmentation can be improved by chemical peeling and laser irradiation, while skin sagging mainly relies on dermal fillers. Although collagen fillers and microspheres fillers can fill the skin, neither of them can provide a sustained filling effect. Herein, a kind of dermal filler composed of collagen, poly(L-lactic acid) (PLLA) and poly(lactic-co-glycolic acid) (PLGA) (PLLA/PLGA microspheres/collagen) is developed to make up for the above shortcomings. PLLA/PLGA microspheres/collagen has good injectability and biocompatibility. In vitro studies indicate that PLGA microspheres of Col-50%PLLA/PLGA and Col-25%PLLA/PLGA show massive degradation on day 1 of complete collagen degradation, meeting the study objectives of continuous improvement of skin sagging. Furthermore, injecting composites into SD rats, 50%PLLA/PLGA and Col-25%PLLA/PLGA are proven with macrophage infiltration, TGF-β expression, and endogenous collagen regeneration. The developed PLLA/PLGA microspheres/collagen composites with good biocompatibility and sustained filling property hold great promise for improved treatment of skin sagging as well as other soft tissue augmentation.