Fibroblasts: what are we talking about?
Like bones, tendons, ligaments and cartilage, skin is part of what we call connective tissue. Connective tissues provide filling, support, elasticity and protection.
The cells most commonly found in connective tissues are fibroblasts, whose role is to secrete and process the components that maintain the structural integrity of these tissues.
Also known as support cells, they synthesize the components of the extracellular matrix, made up of the fibrillar component (collagen fibers, reticular fibers and elastic fibers), which ensures the support, strength, elasticity and mechanical cohesion of connective tissues; and the fundamental substance, which has a mechanical support, compressive strength and filtering function.
The dermis is the deepest layer of the skin, providing structure, strength, nutrition and suppleness. It is mainly composed of dermal fibroblasts.
Dermal fibroblasts produce the components of the extracellular matrix, the network that binds cells together, providing support and enabling them to interact with each other. They also contribute to the initiation and growth cycle of hair follicles, and play an important role in wound healing.
Dermal fibroblasts work continuously to renew dermal components.
When skin structure is damaged, fibroblasts multiply and migrate to the wound, helping to produce extracellular matrix, regulate ongoing inflammation and repair tissue. Myofibroblasts, a specialized subpopulation of differentiated fibroblasts, are involved in synthesizing the proteins responsible for wound contraction.
As healing progresses, myofibroblasts are replaced by fibroblasts, which deposit a fibrotic collagen-rich scar tissue matrix.
As we age, fibroblasts gradually lose their biological activity.
Collagen loss in the body begins between the ages of 18 and 29. After the age of 40, the human body loses around 1% of collagen per year. The extracellular matrix fibers are weaker and less dense, leading to a thinning and loss of elasticity in the dermis.
Given their biological role, stimulating dermal fibroblasts could accelerate wound healing and improve skin structure by increasing tone and hydration, and reducing wrinkles.
But for a cosmetic active ingredient to stimulate the activity and proliferation of fibroblasts, it must first penetrate the epidermis to reach the dermis.
This is very difficult, as the skin is designed as a barrier to prevent the entry of foreign elements.
So which cosmetic active ingredients should be used?
Retinol is a retinoid, derived from vitamin A. Applied topically, retinol and its derivatives stimulate the cellular activity of keratinocytes, fibroblasts and melanocytes. In this way, they help to increase the synthesis of collagen, which gives the skin strength, and glycosaminoglycans, such as hyaluronic acid, which binds to water, increasing the hydration and thickness of the epidermis.
AHA AND BHA ACIDS
Exfoliation of the upper layers of the epidermis increases the activity of fibroblasts and the production of collagen, hyaluronic acid and elastin. This superficial peeling can be achieved by rubbing the skin with abrasive substances, or by applying chemical active ingredients such as AHA and BHA acids.
Peptides are small sequences of amino acids that are small enough to penetrate part of the epidermis. They can then reach the dermis and bind to specific receptors in fibroblasts to stimulate their activity.
Estrogens modulate the activity of epidermal keratinocytes, dermal fibroblasts and melanocytes. Their effects on skin physiology are therefore significant.
During the menopause, estrogen production drops, reducing collagen synthesis by fibroblasts. As a result, the skin loses tone and thickness. Dryness, itching, wrinkles and skin fragility appear. Oral administration or topical application of estrogen has been shown to increase fibroblast activity and thus improve hydration, tone and elasticity of the skin structure.
Other solutions...Collagen-based dietary supplements
Opting for hydrolyzed collagen-based dietary supplements to stimulate collagen production enables you to benefit from the dual action of collagen digestion on the dermis.
On the one hand, free amino acids provide the building blocks for the synthesis of collagen and elastin fibers; on the other, oligopeptides activate receptors on the fibroblast membrane, stimulating the production of collagen, elastin and hyaluronic acid.
& aesthetic medicine treatments
Aesthetic medicine treatments to stimulate collagen and elastin synthesis paradoxically rely on damaging the deeper layers of the skin to stimulate fibroblasts to repair the lesion. For example, the appearance of numerous micro-plaques by microneedling stimulates the release of various growth factors, useful for increasing the synthesis and deposition of collagen and elastin in the dermis.
Another treatment, biostimulation, is based on the cutaneous micro-injection of active ingredients that stimulate the action of fibroblasts - vitamins (A, C, E, nicotinamide), low-molecular-weight hyaluronic acid, amino acids, minerals, antioxidant enzymes or biomimetic peptides - to achieve an aesthetic and functional improvement in the skin.