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Extracellular Matrix (1)


Beauty products advertisements are everywhere, making more and more people aware of the importance of collagen in skincare. However, besides collagen, what other important components does our skin have? Understanding the composition of our skin is essential in maximizing the effects of different skincare products.

Our skin is divided into three layers: the epidermis, dermis, and subcutaneous layer. Collagen, which we often talk about, is mainly found in the dermis. When collagen is lost, it can lead to skin aging signs such as fine lines, enlarged pores, and loss of elasticity. Within the dermis, different types of cells exist such as fibroblasts, hair follicle cells, vascular cells, and sweat gland cells. The spaces between cells are called the extracellular matrix (ECM).

The ECM acts as the backbone of a building, providing cells with a place to reside. Collagen is one of the primary components of the ECM. The ECM is composed of large molecules secreted by cells and distributed on the surface or between cells. These substances affect the physiological activities of cells, including shape, structure, function, survival, proliferation, differentiation, and migration.

The ECM is mainly composed of some polysaccharides and proteins, including proteoglycans, structural proteins, and glycosaminoglycans (GAGs). This article will focus on GAGs.

GAGs are long-chain polysaccharides composed of repeating disaccharide units. The disaccharide unit is usually composed of an amino sugar (either glucosamine or galactosamine) and a uronic acid. They are classified into six types based on different sugar bases, linkages, sulfation degrees, and positions, including hyaluronic acid, chondroitin sulfate, dermatan sulfate, heparan sulfate, heparin, and keratan sulfate. One of the most well-known GAGs is hyaluronic acid.

Hyaluronic acid is the only non-sulfated GAG with an exceptionally long chain. Typically, GAGs contain less than 300 sugar residues, while hyaluronic acid can contain up to 100,000 sugar residues. Due to the high density of negatively charged hydrophilic groups on its surface, hyaluronic acid can bind a vast amount of water molecules, even at low concentrations, forming a viscous gel that occupies a large space. Its physiological function is to allow water to enter the cell gap, bind with proteins to form a protein gel, stick cells together, maintain normal cell metabolism, and retain cell moisture.

Knowing the importance of different skin components can help us choose the right skincare products and maintain healthy skin. In the next article, we will continue to explore other important skin components.