Functional Characterization of β1-Integrin-positive Epidermal Cell Populations
Michelle M. van Rossum A1, Manon E. J. Franssen A1, Wendy A. H. Cloïn A1, Gerard J. M. van de Bosch A1, Jan B. M. Boezeman A1, Joost Schalkwijk A1, Peter C. M. van de Kerkhof A1, Piet E. J. van Erp A1
Epidermal keratinocytes are heterogeneous and can be divided into stem cells (strong β1-integrin expression) with unlimited clonogenic potential, transient amplifying cells (weaker β1-integrin expression) with restricted proliferative capacity and terminally differentiated cells (no β1-integrin expression) that have lost the capacity to divide. We tested the hypothesis that cell kinetic characteristics of the epidermal subpopulations differ. Single cell suspensions from small human skin punch biopsies were sorted flow cytometrically into a β1-integrin weakly positive (dim) and strongly positive (bright) subpopulation and the clonogenic potential was compared in cell culture experiments. Image analysis was used to determine growth characteristics of the colonies. We found that cell size in the β1-integrin bright subpopulation increased when colonies aged, whereas this was constant in the dim subpopulation. The total number of colonies formed and the growth rate of the colonies were higher in the β1-integrand cells than in the bright subpopulation. Experimental data from this study confirm the hypothesis that cell kinetic characteristics of β1-integrin dim and bright cells are different. Combining flow cytometric sorting, cell culture and image analysis provides powerful means for phenotypical and functional characterization of epidermal subpopulations.