Epidermal cells accelerate the restoration of the blood flow in diabetic ischemic limbs

Abstract

Epidermal progenitor cells (EpPCs) were long thought to be unipotent, giving rise only to other keratinocytes but recent studies question this assumption. Here, we investigated whether mouse EpPCs can adopt other antigenic and functional phenotypes. To test this, we injected freshly isolated and cultured EpPCs and transient amplifying cells into diabetic and non-diabetic mouse ischemic hindlimb and followed the cells' fate and the recovery of the ischemic limb blood flow over time. Both freshly isolated and cultured EpPCs and transient amplifying cells were incorporated into the vasculature of the ischemic limb 2 and 5 weeks post-injection, and some expressed endothelial cell but not keratinocyte antigens. Additionally, in the non-diabetic animals, first transient amplifying cells and then EpPCs accelerated the restoration of the blood flow. By contrast, in diabetic animals, only injected EpPCs or unsorted epidermal cells accelerated the restoration of the blood flow. These data indicate that epidermal cells can adopt non-skin phenotypes and functions, and that this apparent pluripotency is not lost by differentiation of EpPCs into transient amplifying cells. They also suggest that epidermal cell therapy might be of therapeutic value in the treatment of diabetic ischemia. Finally, because epidermal cells are readily accessible and expandable, they appear to be ideally suited for use as a non-viral gene delivery therapy.

Antioxidant proteins and reactive oxygen species are decreased in a murine epidermal side population with stem cell-like characteristics

“…Murine epidermal cells and subpopulations were isolated as previously described (Oberley et al 2008; Jiao et al 2004). Briefly, back skin from 1- to 2-day-old C57BL/6J mice was removed and incubated in trypsin 0.25% at 4°C overnight.…”

“…The cellular suspension was spun down and cells resuspended in propidium iodide (0.5 μg/ml; Sigma). Cells are separated into EpSPs and Non-SP populations using a Becton–Dickinson FACSDiVa cell sorter with band filter settings previously described (Jiao et al 2004) and shown in Fig. 1.…”

“…In the skin, stem cells have been localized in the hair follicle bulge and in the basal layer of the epidermis (Cotsarelis et al 1990; Bickenbach 1981; Li et al 1998). Although biochemical markers to recognize epidermal stem cells have been identified (Tani et al 2000; Trempus et al 2003; Liu et al 2003; Pellegrini et al 2001; Jiao et al 2004; Jaks et al 2008), challenges remain to isolate live epidermal stem cells. We and others have previously shown that the use of fluorescent dyes in conjunction with flow cytometry allowed the isolation of a cellular population termed side population (SP) (Goodell et al 1996) with epidermal stem cell characteristics (EpSPs) (Redvers et al 2006; Trempus et al 2003; Jiao et al 2004; Dunnwald et al 2001).…”

“…Although biochemical markers to recognize epidermal stem cells have been identified (Tani et al 2000; Trempus et al 2003; Liu et al 2003; Pellegrini et al 2001; Jiao et al 2004; Jaks et al 2008), challenges remain to isolate live epidermal stem cells. We and others have previously shown that the use of fluorescent dyes in conjunction with flow cytometry allowed the isolation of a cellular population termed side population (SP) (Goodell et al 1996) with epidermal stem cell characteristics (EpSPs) (Redvers et al 2006; Trempus et al 2003; Jiao et al 2004; Dunnwald et al 2001). Homeostasis of the epidermis is dependent on stem and progenitor cell renewal and their renewal and fate are influenced by numerous intrinsic and extrinsic factors, including the microenvironment (Xie and Spradling 2000; Li and Xie 2005).…”

“…Therefore, the aim of our study is to determine the redox microenvironment of freshly isolated (non-cultured) epidermal progenitor cells and their more differentiated progeny obtained from murine epidermis. We have previously defined our EpSPs and Non-SPs cell populations and showed that the EpSPs have characteristics of undifferentiated cells, while Non-SPs have characteristics of more differentiated progenitor cells (Jiao et al 2004; Oberley et al 2008; Dunnwald et al 2003). The results of our study presented here show that EpSPs have decreased antioxidant protein levels and enzymatic activity and produce less ROS compared to their progeny.…”