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Skin cells
Glycosaminoglycans
Glycosaminoglycans (GAGs), also known as mucopolysaccharides, are polysaccharides that deal with the support and maintenance of skin structural proteins such as collagen and elastin. Frequently occurring glycosaminoglycans include hyaluronan and chondroitin sulphate, which function as water-binding molecules that can hold nearly 1000 times their own weight. This ability may serve to provide moisture for other skin components (i.e., collagen and elastin). For this reason, glycosaminoglycans are often used in skincare and are renowned for being excellent ingredients for increasing overall hydration. Glycosaminoglycans may also inadvertently supply anti-ageing benefits.
Examples of common glycosaminoglycans are chondroitin 6-sulphate, keratan sulphate, heparin, dermatan sulphate, and hyaluronate.
Glycosaminoglycans (GAGs) have widespread functions within the body. They play a crucial role in the cell signalling process, including regulation of cell growth, proliferation, promotion of cell adhesion, anticoagulation, and wound repair.
GAGs retain water and form a gel substance through which ions, hormones and nutrients can freely move.
The main component of this gel is hyaluronic acid, which is a large polysaccharide made of glucuronic acid and glucosamine that attracts water and aids repair or growth.
Fibroblast
A fibroblast is a type of cell that is responsible for making the extracellular matrix and collagen. Together, this extracellular matrix and collagen form the structural framework of tissues in humans and play an important role in tissue repair. Fibroblasts are the main connective tissue cells present in the body.
Elastin
Like collagen, elastin is present in many structures in the body, not just in the skin. However, elastin makes up only around 3% of the skin, whereas collagen makes up 70% of the dry mass of skin. Degradation of elastic fibres is associated with UV exposure, and elastosis is one of the key features of photo-aged skin.
The fact that new elastin fibres are not produced is a challenge in the aesthetic industry.
Collagen
Collagen is the most abundant protein in the body. It’s the main component of connective tissue and is found not only in fibrous tissue like the skin but also in tendons, ligaments, cartilage, bones, corneas, and blood vessels.
There are 18 collagen subtypes, 11 of which are in the dermis of the skin.
Types of collagens
The basal lamina serves as structural support for tissues and as a permeable barrier to regulate movement of both cells and molecules.
The dermal-epidermal junction contains type IV collagen, laminin, and highly specialised type VII collagen.
During wound healing, type III collagen appears in the wound about four days after the injury. Wound collagen or type III is immature collagen tissue and does not provide a great deal of tensile strength. It’s initially deposited in the wound in a seemingly random fashion.
It takes around three months for type III collagen to mature into type I collagen.
As skin ages, reactive oxygen species, associated with many aspects of ageing, lead to increased production of the enzyme collagenase, which breaks down collagen. Then fibroblasts, the critical players in firm, healthy skin, lose their normal stretched state. They collapse, and more breakdown enzymes are produced. People in their 80s have four times more broken collagen than people in their 20s.
Immune functions of the skin
Langerhans cells are ‘guard’ cells, found mainly in the Stratum Filamentosum (Spinosum) but start in the dermis.
They move across the skin and are stimulated to action by the entry of foreign materials, acting as macrophages to engulf bacteria.
If someone has a bad immune system, any micro wound treatment will not be as effective.
