Population of Rh123dim human keratinocytes form holoclones

The aim of our studies was to develop an efficient strategy to isolate human early epidermal progenitors for experimental and potential clinical purposes. We employed fluorescence-activated cell sorting (FACS) to isolate cells that poorly accumulate metabolic Rhodamin123 (Rh123) dye. We noticed that similarly to a population of β1-integrin bright (β1^bright) cells, a population of Rh123 dull (Rh123^dim) cells is highly enriched for cells growing holoclones, colonies composed of the most primitive keratinocytes. Furthermore, Rh123^dim cells express several morphological features of primitive undifferentiated cells and are also highly motile. We postulate that these cells could become an important source of epidermal progenitors to expand keratinocytes for clinical purposes.