Collagen diversity in human skin: Aging, wound healing, and disorders

Collagen is an essential skin protein, accounting for 75 % of the skin's dry weight. The collagen superfamily encompasses a diverse group of proteins with a variety of structures that fulfil a wide range of functions. The half-life of collagen in the skin is generally estimated at 10 to 15 years; however, the expression pattern of the different types of skin collagen varies throughout life. Both intrinsic and extrinsic factors influence collagen turn-over within the different skin layers. In this review, we discuss current knowledge of the different types of collagen present in human skin, focusing on insights gained from research exploring the dynamic roles of these proteins in skin development, homeostasis including aging, collagen-linked pathologies, adaptability in response to stress, and wound healing-related processes and disorders. Specificities of skin diversity due to ancestral origin and gender will also be discussed.