Vitalisation of dermal stem cells for skin rejuvenation

Only embryonic stem cells are pluripotent, meaning that they can develop into all cell types of the body, and are thus capable of forming an entire organism. In adult tissues, only multi- or unipotent stem cells are found, indicating that they can differentiate into more than one cell type or only one cell type, respectively. Stem cells are found in virtually all adult tissues where they are responsible for a continuous supply of new cells essential for repair and regeneration. Because adult stem cells are an ethically correct source, research on stem cells of adult tissues has advanced considerably in recent years and new findings are revolutionising the field of regenerative medicine.

The rarely explored stem cells of the dermis

In the skin, especially the stem cells found in the epidermis are well characterised. The epidermis is a stratified epithelium that is constantly renewed throughout life. Constant renewal and repair is essential for the maintenance of the normal barrier function, which protects the body from physical and chemical damage, infection and dehydration. Renewal of the epidermis is mediated by stem cells in the basal layer of the epidermis. Protection or stimulation of stem cells in the epidermis has become a hot topic in cosmetics. In vitro test systems using epidermal stem cells have been established which allow claims for epidermal stem cell actives. But what about the stem cells in the dermis? Until now, they have not been addressed by cosmetic treatments although they might play a decisive role in skin ageing. Fibroblasts, the prominent cell type in the dermis, are responsible for the continuous production of collagen and elastin. These proteins form the so-called extracellular matrix, a three dimensional structure that confers elasticity and firmness to the skin. Ageing skin is characterised by an increasing number of senescent fibroblasts. These cells have not only stopped to produce collagen and elastin but even start to break down the existing matrix.1 The replacement of these senescent cells by new fibroblast cells can only be provided by dermal stem cells. There must be a pool of slowly dividing dermal stem cells. But the number of divisions stem cells of adult tissues can undergo is limited (Hayflick limit), thus, exhaustion of this pool of cells limits the lifespan of the tissue. Treatments that reinforce the functional ability of tissue stem cells, have a real anti-ageing potential.