Side population in adult murine epidermis exhibits phenotypic and functional characteristics of keratinocyte stem cells

Abstract

Based on functional studies in the bone marrow, it has been suggested that the ability to efflux Hoechst 33342 may represent a universal stem cell trait. In this phenotypic and functional characterization of the Hoechst side population (SP) in adult murine epidermis, we demonstrate that these cells are a rare subset of the keratinocyte stem cell-enriched ␣6 bri CD71 dim fraction comprising SSC low ͞K14 ؉ ͞CD34 ؊ ͞Oil red O ؊ ͞c-kit ؊ ͞CD45 ؊ keratinocytes. Epidermal SPs have the smallest cell and nuclear size but exhibit the highest nuclear-to-cytoplasmic ratio of any fraction examined, consistent with a primitive cell type. Although SPs demonstrated poor cumulative in vitro proliferative output, they exhibited sustained epidermal tissue-regenerative activity in vivo compared with unfractionated and non-SP cells. Collectively, these results indicate that the epidermal SP contains the most potent keratinocyte stem cell population in skin epithelium.skin ͉ self-renewal ͉ tissue regeneration ͉ cell cycle ͉ proliferation

Isolation and characterisation of a novel trophoblast side-population from first trimester placentae

“…This revealed that side-population trophoblasts are a transcriptomically distinct population within the placenta and express a number of genes characteristic of other pluripotent stem cell populations and murine trophoblast stem cells. The Hoechst side-population technique has been used to identify adult stem cell populations in a range of organs including the heart, liver and kidney, as well as epithelial tissues with well-defined stem cell populations such as skin, colon and the corneal limbus (Redvers et al 2006, Samuel et al 2009, Shaharuddin et al 2014. In this work, we used this technique to isolate a population of trophoblasts from first trimester placental villi that are 98.5% pure.…”

“…To overcome this, we used the Hoechst side-population technique of isolating progenitor and stem cell populations (Redvers et al 2006, Samuel et al 2009, Shaharuddin et al 2014 to isolate a novel population of trophoblasts from first trimester placentae and characterised these side-population trophoblasts with respect to more differentiated trophoblast populations. This revealed that side-population trophoblasts are a transcriptomically distinct population within the placenta and express a number of genes characteristic of other pluripotent stem cell populations and murine trophoblast stem cells.…”

Niche regulation of corneal epithelial stem cells at the limbus

“…Future studies are needed to determine whether ABCG2 is expressed not only in the limbal tissue, whether other members of ABC transporter family may be expressed by some corneal cells, and whether cells other than SCs can also express ABCG2. Although epidermal SP cells have been proven devoid of melanocytes or dendritic cells [83], a preliminary study did show that both human and rabbit limbal SP cells contain non-epithelial cells such as lymphocytes [84], raising the question whether it is valid to use SP as a source of limbal SCs.…”

Studying the expression patterns of OCT4 and SOX2 proteins in regenerating rabbit ear tissue

“…Tai et al showed that adult stem cells expressed OCT4 in several human tissues such as liver, kidney and pancreas (Tai et al, 2005). OCT4 expression was also reported in side populations of keratinocytes in mouse epidermis (Redvers et al, 2006) and resident cells in the human hair follicle bulge (Yu et al, 2006). Some studies addressed OCT4 protein expression in mesenchymal stem cells from different origins (Izadpanah et al, 2006;Greco et al, 2007;Riekstina et al, 2009;Dudakovic et al, 2014).…”