Recent progress of dermal implants for aged skin rejuvenation: a review

Skin aging is a multifactorial biological process marked by a progressive decline in regenerative capacity, chronic low-grade inflammation, and increased susceptibility to cutaneous disorders, including malignancies. It is driven by both intrinsic factors-such as genetic predisposition and hormonal changes-and extrinsic influences like ultraviolet radiation, environmental pollutants, and unhealthy lifestyle habits. Conventional topical treatments, including moisturizers and sunscreens, offer only transient effects due to limited dermal penetration. In recent years, dermal implants have emerged as promising alternatives for skin rejuvenation, providing enhanced bioavailability, prolonged therapeutic effects, and minimal invasiveness. Among various biomaterials, collagen stands out for its excellent biocompatibility, low immunogenicity, and intrinsic bioactivity. This review systematically summarizes recent progress in implantable strategies for aged skin repair, categorizing materials into five major types: inorganic fillers, synthetic polymers, hyaluronic acid-based, collagen-based, and composite implants. Their structural properties, regenerative mechanisms, and clinical performances are critically compared. Special attention is given to collagen-based implants-hydrogels, fibers, and microspheres-for their roles in modulating inflammation, promoting endogenous collagen synthesis, and facilitating dermal remodeling. The review concludes with an overview of commercialized products and discusses future directions toward precision anti-aging therapies.