Immunohistological localization of endogenous unlabeled stem cells in wounded skin.

Various types of endogenous stem cells (SCs) participate in wound healing in the skin at different anatomical locations. SCs need to be identified through multiple markers, and this is usually performed using flow cytometry. However, immunohistological identification of endogenous stem cells in the skin at different anatomical locations by co-staining multiple SC markers has been seldom explored. We examined the immunohistological localization of four major types of SCs in wounded skin by co-staining for their multiple markers. Hematopoietic SCs were co-stained for Sca1 and CD45; mesenchymal SCs for Sca1, CD29, and CD106; adipose SCs for CD34, CD90, and CD105; and endothelial progenitor cells and their differentiated counterparts were co-stained for CD34, Tie2, and von Willebrand factor. We found Sca1(+)CD45(+) SCs in the epidermis, dermis and hypodermis of wounded skin. Sca1(+)CD29(+) and Sca1(+)CD106(+) mesenchymal SCs, CD34(+)CD105(+), CD34(+)CD90(+), and CD90(+)CD105(+) adipose SCs, as well as CD34(+)Tie2(+) endothelial progenitor cells were also located in the epidermis, dermis, and hypodermis. This study demonstrates the feasibility of using immunohistological staining to determine the location of SCs in wounded skin and the intracellular distribution of their molecular markers.