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Aging and the reduction of Stem Cells in the Skin

Age-related decrease in CD271+ cells in human skin.
Akamatsu H, Hasegawa S, Yamada T, Mizutani H, Nakata S, Yagami A, Matsunaga K.
J Dermatol. 2015 Aug 24. doi: 10.1111/1346-8138.13048. [Epub ahead of print]


-Stem cells are trendy. To summarize, they can be divided into pluripotent (often embryonic) stem cells and differentiated stem cells

Aging can be divided into:
-Epidermal aging has less to do with the appearance of wrinkles (mainly a dermal process), than with textural changes (a rough appearance)
-Dermal aging which is more related to wrinkling because of the loss of volume

CD271+ (p75NTR) are multipotent (non-embryonic) stem cells with a strong proliferative potential
-In the epidermis, these stem cells reside in the Basal layer (Stratum Basale). Upon dividing, one cell moves and diferentiates to an epidermal dead cornified keratinocyte. The other cell remains as a stem cell in the basal layer.

-They can also be seen in the dermis and can probably differentiate into fibroblasts (see below)

In this study from Japan skin biopsies were taken in 23 females aged between 10 and 90 on unexposed skin (trunk)

Results revealed:
histological changes related to aging (epidermis thinned, reduced papillation and number of cells. dermis showing reduced collagen bundles)
immunohistochemistry showed CD271+ cells mainly in the epidermis above the dermal papillae. Photographs in the article clearly show a strong density as visible in the sample taken in a 27 year old female. The density gradually diminishes so as to be almost absent in the specimen taken from an 84 year old female (cd271+ were also sparsely also found in the dermis)

All in all, when comparing subjects in their 60s vs in there 20s, the number of Cd271+ cells in the former group is one third of the density in the latter group.

-The decrease is clear for epidermal CD271+ cells which translates into the reduction of epidermal keratinocyte turnover
-As for the dermis it can be speculated that the reduction in CD271+ cells translates into the reduction of fibroblast cell population, with resulting reduction of hyaluronic acid and collagen production.
CD271+ cells are also reduced in chronic venous ulcers

-While the differences are clear for epidermal CD271+ stem cells, the conclusions are more difficult to draw from dermal ones (they are less numerous in the dermis to begin with)
CD271+ provides a new understanding of deficiency present in aging and diseases and this has potential to develop new treatment strategies.

Article selection: Prof Dr Jean-Hilaire Saurat – dermatologist. Geneva, Switzerland