Figure 4. The secretome of NSCs and ECs undergoing endothelial morphogenesis.

Secreted factors from undifferentiated (UD) and differentiated (D) D3, STROC05 and CTXOE03, as well as plain media (M), were measured using ELISAs. Additionally, 7 day co-cultures at a ¼x (0.25*opt), optimal (opt), or 4x optimal (4*opt) ratio, as well as the evolution of factor secretion of the optimal ratio over time were assessed. All factors tested here were secreted from differentiated ECs, but were mostly absent in dividing undifferentiated D3. In contrast, monocultures of NSCs under proliferative or differentiated conditions mostly released low levels of the factors, predominantly factors associated with a stabilization of the vasculature (e.g. TGF-β1, ANG-1). CTXOE03 however expressed high levels of VEGF-A, especially when differentiated. A dramatic change in the level and profile of factor release is observed after coculture. Especially BDNF, VEGF-A, PDGF, ANG-1, TGF-β1 and bFGF showed distinctive cell line profiles in coculture, indicating that NSCs potentially exert differential effects on EC behavior through the interaction of secreted factors. The temporal profile further indicates how these secreted factors evolve from in concurrence with endothelial morphogenesis and cellular differentiation. Data represent the mean and error bars indicate 1 standard deviation.