Figure 3.

Increasing the duration of the conditioning period did not increase the number of capillary-like structures. Representative microscope photographs taken on gels after human umbilical vein endothelial cells were cultivated with irradiated fibroblasts seeded in fibrin gels with medium conditioned by dermal fibroblasts under hypoxic conditions during 1 week (upper panels) or 2 weeks (lower panels). Despite a more extended period of conditioning, the 2 weeks-condition did not promote a higher number of structures. It is possible that fewer structures were present in this latter condition, but the 3D context did not allow a precise determination of such parameters using brightfield microscopy. Once again, tubulogenesis was visible with the inner vacuole forming the lumen.