Fig. 6.

Cell type-specific antigen expression: Endothelial cells and HSF were analyzed with regard to the expression of endothelial and nonendothelial antigens by FACS analysis (A), Western blotting (B), and immunofluorescence microscopy (C). FACS analysis showed that both HUVEC cell types express high levels of vWF (81.6 ± 3.5; 86.0 ± 4.1), VE-cadherin (83.9 ± 2.3; 95.2 ± 1.1), PECAM-1 (76.5 ± 5.0; 80.3 ± 4.3), and VEGFR-2 (87.4 ± 3.6; 91.4 ± 3.9) compared to the expression levels of HSF. All three cell types displayed the expression of CD133, claudin 5, Lyve-1, and CXCR4. Thy-1, a specific fibroblast marker, was only detectable in HSF. CD34 was not detected in any of the three cell types. B Western blot analysis verified the FACS data. C Immunofluorescence microscopy showed cellular localization of the above antigens. vWF was detected as punctual staining in the perinuclear region of primary and hTERT-HUVECs but not in HSF. Moreover, adhesion molecules (PECAM-1, VE-cadherin, claudin 5) were detected at the cell border in endothelial cells, whereas HSF only expressed claudin 5 in an irregular manner. All cell lines expressed CD133 and CXCR4 in an irregular pattern all over the cells. Thy-1 was exclusively found in HSF and not in cells of endothelial origin. Scale bars a 40 μm; aa, ad 100 μm