Recent progresses of collagen dressings for chronic skin wound healing

The skin plays a fundamental role in regulating the body's internal balance and protecting against external traumas. A broad variety of environmental risk factors frequently result in acute skin wounds, whose inappropriate treatments would lead to chronic skin wounds that are difficult to heal. Traditional dressings have been widely used to repair chronic skin wounds, however their drawbacks such as insufficient hemostatic efficacy and non-moist environment have severely limited their clinical applications. As the principal component of skin, collagen has always been a research hotspot in the field of chronic skin wounds due to its advantages of low antigenicity, high biocompatibility and superior bioactivity. Collagen-based dressings have been increasingly developed to heal the chronic wounds during the past decades, arising from their capability in decreasing protein and electrolyte losses in wound exudate, preventing bacterial contamination, permitting less painful dressing changes, and improving the healing quality. This review overviews recent progress of collagen dressings for chronic skin wound healing. Various commonly used wound dressings for wound management have been first introduced. Collagen wound dressings have been categorized as films, sponges, hydrogels, nanofibers, and powders, and their efficacy has been compared. The critical functions of collagen dressings in wound healing, such as stopping bleeding, shortening inflammation, promoting angiogenesis, and stimulating tissue regeneration have been elaborated. The clinical applications of collagen dressings to repair different types of chronic wounds have been thoroughly summarized. A comprehensive list of commercialized collagen dressings has been updated, and an outlook of collagen dressings have been finally speculated.