Figure 6

Expression of cellular marker molecules by human umbilical vein endothelial cells (HUVEC). Using indirect immunofluorescence staining, highly positive signals (green) were detected for A) CD31 of fresh cultivated cells and B) CD31 of cryopreserved cells, E) von Willebrandt factor (vWF) of fresh cultivated cells and F) vWF of cryopreserved cells. The presence of C) CD31 (green) and G) vWF (green) was detected in the endothelium of native human umbilical cord veins, serving as a control. Immunohistochemical staining verified the presence of D) CD31 (red) and H) vWF (red) in the endothelium of native human umbilical cord veins. Using flow cytometry analysis, cellular marker expression of short-term (group A, n = 4) and long-term (group B, n = 4) cryopreserved cells from primary cultures (passage 0) was studied directly after I) thawing and J) in passage 3 of recultivation. By comparison, non-cryopreserved fresh cells (n = 3) from I) primary cultures and J) passage 3 were analyzed in parallel as a control group. Using indirect immunofluorescence staining, highly positive signals (green) were also detected for the cellular markers K) CD144 of fresh cultivated cells and L) CD144 of cryopreserved cells, M) endothelial nitric oxide-synthase (eNOS) of fresh cultivated cells and N) eNOS of cryopreserved cells. Cell nuclei staining is pictured in blue, present in A-H and K-N. All studies of marker expression are exemplarily shown for cells of passage 3.