Expression and immunotyping of stem cell markers in hAFS cells using RT-PCR and flow cytometry. (a) RT-PCR analysis showed that expression of various stem cell markers was sustained over the population doublings. (b) hAFS cells expressed high levels of mesenchymal stem cell markers, including CD44, CD90, CD73 and CD105; however, they did not express HLA-DR and CD45 at passages 7 and 11. (c) FACS plots for MSC markers of (b). hAFS, human amniotic fluid stem; MSC, mesenchymal stem cells.