The skin is the first line of the protective barrier that is constantly exposed to various insults, such as physical and chemical factors, microbes, and pathogens, often causing skin injuries. The healing of injured skin is a highly dynamic and organized process orchestrated by the interactions of various cell types, cytokines, and extracellular matrix. However, chronic inflammation and excessive collagen synthesis during wound healing can develop skin fibrosis, eventually becoming a permanent scar. Fibrotic skin or scarring frequently compromises skin function and causes mental trauma, physical pain, and a heavy financial burden. Despite this, specific and effective anti-scarring drugs are still lacking in clinical practice. Over the past several years, studies using mouse models, signal cell analysis, and lineage tracing techniques have unraveled significant molecular mechanisms underlying scar formation. This review discusses the latest research advances on scar formation during skin repair. Further study of the scar formation mechanisms will provide novel insights into the possible development of anti-scar and tissue-regeneration drugs.
