While collagen is critical in maintaining healthy, youthful skin, there is another protein in the skin that is equally important for the health and appearance of skin – Elastin – a protein in connective tissue that is elastic and allows many tissues in the body to restore their shape after stretching or contracting. Elastin is a protein primarily composed of the amino acids “glycine, valine, alanine, and proline”. Just as collagen, it is produced by the connective tissue cells called fibroblasts. Fibroblasts secrete tropoelastin, the soluble building blocks of elastin made up of 830 amino acids with an irregular or random coil conformation. Tropoelastin molecules are then cross-linked in a reaction catalyzed by the enzyme lysyl oxidase, forming a durable, resilient network of elastin fibers (polymer of tropoelastin) that confer skin its resilience/elasticity property. Desmosine and isodesmosine are types of links for the tropoelastin molecules. A desmosine cross-link is formed from three allysyl side chains plus one unaltered lysyl side chain from the same or neighboring polypeptides. (Allysine is a derivative of lysine, used in the production of elastin and collagen. It is produced by the actions of the enzyme lysyl oxidase in the extracellular matrix and is essential in the crosslink formation of both collagen and elastin.) Desmosine is responsible for the rubber properties of elastin. The amount of elastin in the skin usually peeks in adolescence or early adulthood and declines thereafter. Fibroblasts in aged skin have a much reduced capacity to produce new elastin.

Besides elastin, another protein called fibrillin is required for the formation of elastic fiber system in the skin. The Elastic fiber is composed of the protein fibrillin and elastin. Fibrillin is a glycoprotein, which is essential for the formation of elastic fibers found in connective tissue. This glycoprotein adds elasticity and strength to connective tissue. Fibrillin is secreted into the extracellular matrix by fibroblasts and becomes incorporated into the insoluble microfibrils -a very fine fibril, or fiber-like strand composed of end-to-end polymers of fibrillin. Microfibril functions as the scaffold for elastin.

There are three types of elastic fibers forming the elastic system of the skin with different staining characteristics and ultrastructural patterns as well as variations in elastin amount. The three different fiber types of the elastic system belong to a continuous series: oxytalan-elaunin-elastic. All of the fiber types are composed of collections of microfibrils with increasing amounts of elastin in the given sequence. Ultrastructurally, a characteristic elastic fiber consists of two morphologically different components: a centrally located solid cylinder of amorphous and homogeneous elastin surrounded by tubular microfibrils.

The elastic system of normal human skin was studied and examined by both light and electron microscopy.  Three are three different types of fibers identified by light microscope: oxytalan, elaunin and elastic. Oxytalan fibers are the thin most superficial ones that directed perpendicularly to the dermoepidermal junction. They start from a plexus of elaunin fibers which is connected with the thicker elastic fibers of the reticular dermis. Elaunin fibers are formed from a deposition of elastin between oxytalan fibers. It is found in the periodontal ligament and in the connective tissue of the dermis, particularly in association with sweat glands.

Electron microscopic studies have revealed that oxytalan, elaunin and elastic fibers differ in the amount of elastin among the network of microfibrils. An oxytalan fiber is composed of a bundle of microfibrils that are identical to the microfibrils in the elastic fiber. Oxytalan fibers are formed by bundles of tubular microfibrils without amorphous material (elastin). In the elaunin fibers the amorphous material is sparse and the dispersed amorphous material is intermingled among the microfibrils. In the elastic fibers, elastin (amorphous material) is abundant and compact.

Compared to collagen in dermatological research and the cosmetic care industry, elastin is a commonly overlooked area of skin care. The strong focus on collagen has actually led to research into elastins being neglected over time. A few methods, however, have had some level of success in maintaining or restoring elastin levels in aging skin.

• Retinoic acid
• MMP inhibitors
• Skin tissue remodeling/rejuvenation procedures
• Topical tropoelastin
• Ethocyn