Extensive tissue-regenerative capacity of neonatal human keratinocyte stem cells and their progeny
Amy Li, Normand Pouliot, Richard Redvers, Pritinder Kaur
Amy Li, Normand Pouliot, Richard Redvers, Pritinder Kaur
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Extensive tissue-regenerative capacity of neonatal human keratinocyte stem cells and their progeny

Abstract

Given our recent discovery that it is possible to separate human epidermal stem cells of the skin from their more committed progeny (i.e., transit-amplifying cells and early differentiating cells) using FACS techniques, we sought to determine the comparative tissue regeneration ability of these keratinocyte progenitors. We demonstrate that the ability to regenerate a fully stratified epidermis with appropriate spatial and temporal expression of differentiation markers in a short-term in vitro organotypic culture system is an intrinsic characteristic of both epidermal stem and transit-amplifying cells, although the stem cell fraction is most capable of achieving homeostasis. Early differentiating keratinocytes exhibited limited short-term tissue regeneration under specific experimental conditions in this assay, although significant improvement was obtained by manipulating microenvironmental factors, that is, coculture with minimally passaged dermal cells or exogenous supply of the ECM protein laminin-10/11. Importantly, transplantation of all classes of keratinocyte progenitors into an in vivo setting demonstrated that tissue regeneration can be elicited from stem, transit-amplifying, and early differentiating keratinocytes for up to 10 weeks. These data illustrate that significant proliferative and tissue-regenerative capacity resides not only in keratinocyte stem cells as expected, but also in their more committed progeny, including early differentiating cells.

Authors

Amy Li, Normand Pouliot, Richard Redvers, Pritinder Kaur

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Figure 1

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KSCs and TA cells regenerate epithelial tissue better than differentiati...
KSCs and TA cells regenerate epithelial tissue better than differentiating keratinocytes when cocultured with p7 dermal cells. Comparative in vitro tissue-regenerative ability of UF cells (a–c), KSCs (d–f), TA cells (g–i), and differentiating epidermal cells (j–l) in organotypic cultures obtained from 4.5 × 104 (a, d, g, and j) versus 104 fractionated keratinocytes (c, f, i, and l) plated on DEs containing p7 dermal fibroblasts, all harvested at 14 days. Note the relatively poor tissue-regenerative ability of the differentiating α6dim cells (j), which was further decreased by reducing the number of keratinocytes plated to 104 (l). Expression of α6 integrin (b, e, h, and k) in the cultures corresponding to a, d, g, and j revealed that an integrin-positive basal layer (most polarized in the KSC sheet) was present in the epithelium generated from all fractions as well as total UF keratinocytes. Nuclei were counterstained with propidium iodide. Scale bars: 50 μm.