Reprogramming cells for a younger looking skin

In terms of regeneration, the epidermis is one of the most active tissues. This capacity is mostly associated with some of the cells located in the basal layer, consisting in part of epidermal stem cells, which are unspecialised cells able to divide and renew themselves for long periods. Moreover, they can also give rise to progenitor cells, known to be undifferentiated and to present a limited proliferative potential.1 Progenitor cells undergo several rounds of proliferation until they differentiate into keratinocytes. 

The self-renewal capacity of basal cells is maintained in part by the transcription factors OCT4, SOX2 and KLF4. These are stem cell markers that can be regulated by microRNAs such as the microRNA-145 (miR-145). Levels of this non-coding RNA are low in basal cells but increase during differentiation, with a concomitant decrease of the stem cell transcription factors.2 Besides, transition from the basal to the suprabasal layers involves a change in expression of characteristic cell markers: basal keratin 14 (K14) and p63 (required for a high regenerative potential) decrease their expression during differentiation, while suprabasal keratin 10 (K10) increases it. 

With age, this turnover of the epidermis gets affected, leading to the development of ageing signs, such as the emergence of wrinkles and loss of radiance.3, 4