Advances in Molecular Function and Recombinant Expression of Human Collagen.

Collagen is the main protein found in skin, bone, cartilage, ligaments, tendons and connective tissue, and it can exhibit properties ranging from compliant to rigid or form gradients between these states. The collagen family comprises 28 members, each containing at least one triple-helical domain. These proteins play critical roles in maintaining mechanical characteristics, tissue organization, and structural integrity. Collagens regulate cellular processes such as proliferation, migration, and differentiation through interactions with cell surface receptors. Fibrillar collagens, the most abundant extracellular matrix (ECM) proteins, provide organs and tissues with structural stability and connectivity. In the mammalian myocardial interstitium, types I and III collagens are predominant: collagen I is found in organs, tendons, and bones; collagen II is found in cartilage; collagen III is found in reticular fibers; collagen IV is found in basement membranes; and collagen V is found in nails and hair. Recombinant human collagens, particularly in sponge-like porous formats combined with bone morphogenetic proteins, serve as effective scaffolds for bone repair. Due to their biocompatibility and low immunogenicity, collagens are pivotal in tissue engineering applications for skin, bone, and wound regeneration. Recombinant technology enables the production of triple-helical collagens with amino acid sequences identical to human tissue-derived collagens. This review summarizes recent advances in the molecular functions and recombinant expression of human collagens, with a focus on their biomedical applications.