Hydrogels: current biomedical applications and future directions

Hydrogels are highly hydrated three-dimensional polymeric network materials that have attracted considerable attention in medical and biomedical fields owing to their favorable chemical modifiability, physical tunability, biocompatibility, and capacity to mimic key features of native extracellular matrices. With advances in polymer chemistry, crosslinking strategies, stimuli-responsive design, and emerging fabrication technologies, hydrogels have evolved from simple soft materials into multifunctional biomedical systems capable of integrating controlled delivery, tissue support, microenvironmental regulation, biosensing, and disease modeling. These properties make hydrogels particularly relevant for addressing a broad spectrum of human diseases in which conventional therapeutic strategies are often limited by insufficient targeting efficiency, limited therapeutic windows, pronounced systemic side effects, and inadequate restoration of damaged tissue structure and function. In this review, we systematically summarize the design principles and material engineering strategies of hydrogels, including structural construction approaches and functional regulation concepts. We then provide a comprehensive overview of their current biomedical applications, encompassing drug delivery systems, tissue engineering and regenerative medicine, biosensing and diagnostic platforms, as well as cell culture and organoid systems. Building on this foundation, we place particular emphasis on recent progress in hydrogel-based therapeutic strategies across diverse human disease contexts, including wound healing, musculoskeletal system repair, cancer, neurological diseases, cardiovascular diseases, autoimmune disorders, and reproductive system diseases. Finally, we discuss the developmental potential of hydrogels in biomedicine and present an integrated perspective on their clinical translation prospects, with the aim of offering references and insights for the further application of hydrogel materials in future human disease treatment.