Mechanism of Action of Collagen and Epidermal Growth Factor: A Review on Theory and Research Methods.

The most abundant protein found in mammals is collagen, and there are around 28 different types of collagen found in the human body, but there are five types, namely, Type I, Type II, Type III, Type V, and Type X, most generally applied in supplements, and the five common types of collagen are available in various forms and form different sources, which result in various potential benefits. The epidermal growth factor is one of the main growth factor proteins in the skin, which has an important function in the production of collagen, hyaluronic acid, and elastin to keep the skin healthy and dense appearance. It is a single-chain polypeptide of 53 amino acids, which is a potent mitogen for a variety of cells in vivo and in vitro. It triggers cells to grow, produce, and divide proteins, such as collagen. It may increase collagen production in granulation tissue by stimulation of fibroblast proliferation. This review article aims to provide an overview of different collagens and epidermal growth factors from recently published studies and some important directions for future research. The key words search for Collagen, Epidermal growth, Polypeptides, Amino acids, Protein, and tissue engineering were performed using Google scholar, PubMed, and Scopus. Fibrillar collagens are collagen types I, II, III, V, XI, XXIV, XXVII, and non-fibrillar collagens are collagen types IV, VI, VII, VIII, IX, X, XII, XIII, XIV, XV, XVI, XVII, XVIII, XIX, XX, XXI, XXII, XXIII, XXV, XXVI, XXVIII, and XXIX. Collagen I can be found in bone, skin, tendon, cornea and vascular ligature; collagen II can be discovered in cartilage, vitreous body and gristle; collagen III is the main ingredient of reticular fibers which is often found alongside type I, the location of collagen III is also in skin, uterus, intestine, and vessels. Collagen IV can be identified in capillaries, the epithelium-secreted layer of the basement membrane and forms basal lamina. It forms basal lamina, capillaries, and the epitheliumsecreted layer of the basement membrane, while Collagen V can be discovered in bones, skin, cornea, hair, placenta, and cell surfaces. In addition, collagen VI is found in bones, skin, gristle, cornea and vessels, while collagen VII can be found in skin, bladder, mucous membranes, amniotic fluid and umbilical cord. Lastly, collagen VIII is found in the skin, heart, kidney, brain, bones, gristle and vessels. Moreover, collagen X, XI and IX can be found in the gristle.