Keratin 19 as a Stem Cell Marker In Vivo and In Vitro
The skin is a dynamic tissue in which terminally differentiated keratinocytes are replaced by the proliferation of new epithelial cells that will undergo differentiation. The rapid and continual turnover of skin throughout life depends on a cell population with unique characteristics: the stem cells. These cells are relatively undifferentiated, retain a high capacity for self-renewal throughout their lifetime, have a large proliferative potential, and are normally slow cycling. The long-term regeneration of grafted cultured epidermis indicates that epidermal stem cells are maintained in cultures. In animals they can be identified with 3H-thymidine or bromodeoxyuridine based on their property of slow cycling. The development of markers such as keratin 19 also permits their study in human tissues. In this chapter, protocols to study skin stem cells using their property of slow cycling and their expression of keratin 19 will be described in detail. The methods include the double labeling of tissues for keratin 19 and label-retaining cells (autoradiography of 3H-thymidine) in situ. The labeling of keratin 19 by immunofluorescence of by flow cytometry is described for cells in vitro.
key WordsStem cells keratin keratin 19 epidermis hair follicles human skin flow cytometry
- 3.Germain, L., Michel, M., Fradette, J., Xu, W., Godbout, M-J., and Li, H. (1997) Skin stem cell identification and culture: a potential tool for rapid epidermal sheet production and grafting, in Skin Substitute Production by Tissue Engineering: Clinical and Fundamental Applications. (Rouabhia, M., ed.), Landes Bioscience, Austin, TX, pp. 177–210.Google Scholar
- 4.Michel, M., Török, N., Godbout, M.-J., Lussier, M., Gaudreau, P., Royal, A. et al. (1996) Keratin 19 as a biochemical marker of skin stem cells in vivo and in vitro: keratin 19 expressing cells are differentially localized in function of anatomic sites, and their number varies with donor age and culture stage. J. Cell. Sci. 109, 1017–1028.PubMedGoogle Scholar