3D Bioprinting for structural and functional skin regeneration: Technologies, bioinks, and key challenges

As the body's largest organ and primary protective barrier, skin is critical for maintaining physiological homeostasis. Severe skin injuries pose a major global healthcare challenge, with hundreds of thousands of annual deaths attributed to limited transplantable skin availability. 3D bioprinting has emerged as a revolutionary approach to fabricate biomimetic, anatomically precise skin constructs. This review summarizes the research progress of 3D bioprinting in skin structural and functional regeneration: it systematically assesses five core bioprinting technologies (extrusion, inkjet, stereolithography, laser-induced forward transfer, and in situ printing) along with their advantages and limitations in skin fabrication; outlines advancements in skin-specific bioinks (biomaterials, skin cells, growth factors and medicines) and their regulatory roles in regeneration; and discusses achievements and challenges in reconstructing skin vasculature, and pigmentation. Finally, current bottlenecks and future directions for achieving complete structural and functional skin regeneration via 3D bioprinting are comprehensively addressed.