Fig. 5.

The effect of VEGF-A neutralization on directed neurite outgrowth (n=14, vertical bars represent standard error). (A) The effect of VEGF-A neutralizing antibodies on average axon length. Anti-human VEGF-A antibodies were used to neutralize the effect of VEGF-A released from alginate spheres. Concentrations as low as 500 μg/ml were able to block the effect of the VEGF-A/alginate spheres compared to sphere alone controls. (*=p<0.05.) (B) The effect of a VEGFR2 inhibitor on average axon length. A highly specific cell permeable VEGFR2 tyrosine kinase inhibitor was used to block signaling from VEGF-A released from alginate spheres. Concentrations as low as 1 μg/ml were able to block the effect of VEGF-A/alginate spheres compared to sphere alone controls (first bar on the left). (C) The effect of the VEGFR2 inhibitor on femoral–SCG neurovascular co-cultures. The cell permeable VEGFR2 inhibitor was also able to decrease neurite outgrowth elicited by femoral artery segments co-cultured with SCG. (*=p<0.05.) Average axon length (for vessel and non-vessel cultures) at all inhibitor concentrations is normalized to axon lengths with no VEGFR2 inhibitors. On both the vessel and non-vessel sides of the SCG, there is a decreased average axon length compared to the no inhibitor control (first pair of bars on the left). (D) The effect of VEGFR2 inhibitors on the increase in axon outgrowth elicited by femoral artery segments. At each concentration of VEGFR2 inhibitor, average axon length on the non-vessel side of the SCG is normalized to the average axon length towards the vessel. Although VEGFR2 tyrosine kinase inhibitors were able to significantly decrease overall axon length in femoral–SCG neurovascular co-cultures at all inhibitor concentrations tested, the ratio of vessel/non-vessel outgrowth was maintained with significantly more outgrowth observed in the quadrant towards the femoral artery segment compared to the non-vessel quadrant. (*=p<0.05.)