Figure 6: 1 × 105 T17b eEPCs were cultivated on nanofiber scaffolds for 3 days and their morphology analyzed via SEM after critical point drying (c, d, f, g, i, j, l, m) reflected light microscopy after immunofluorescent staining (phalloidin + DAPI) (a, b, e, h, k). Pure PCL scaffolds shrunk due to the drying process, making SEM imaging impossible. Cells attach their pseudopodia to nanofibers (here on a PCL/Coll 25% scaffold) (g). PCL/Coll 75% scaffolds lost their ultrastructure. Cells assume a rather round morphology and built large cell clusters (k, l, m). In areas of high cell density “cobblestone” formation can be observed (here found on a PCL/Coll 50% scaffold) (d, j). Cells are torn apart partially, due to the drying process. Nicely spread cell-monolayers and “cobblestone” formations were observed mainly on PCL, PCL/Coll 5%, and 25% scaffolds (a–g, j). Cells seeded on PCL/Coll 50% lost their polarity towards the scaffolds material (h, i).