VEGF-E attenuates injury after ischemic stroke by promoting reparative
neovascularization
Abstract
Post-stroke angiogenesis improves structural and functional recovery,
outlining the promises of pro-angiogenic therapies. Unfortunately,
vascular endothelial growth factor (VEGF)-A-mediated angiogenesis
resulted in mitigated outcomes, as it significantly increases the risk
of exacerbating injury via destabilization of the cerebrovascular
network. VEGF-E, a non-mammalian VEGF-A homolog, has been reported to
promote stable neovascularization upon skin injuries, and thus
represents an interesting safe alternative to promote post-stroke
angiogenesis. C57BL6/J wildtype mice were subjected to ischemic stroke
using transient middle cerebral artery occlusion (MCAo), and recombinant
VEGF-E was intranasally delivered throughout the subacute phase. Our
results indicate that VEGF-E reduces neuronal loss and improves motor
recovery after stroke. VEGF-E attenuates cerebrovascular permeability at
the injury site and increases the density of mature CD31+ microvessels.
Furthermore, we show that VEGF-E reduces the events of microvascular
stalls and improves brain endothelial cell coverage by perivascular
cells, required for cerebrovascular stability. VEGF-E increases the
density of angiogenic active CD105+ microvessels, while improving the
recruitment of CD13+ pericytes, outlining synergistic effects on
microvessel formation and stabilization. Using cell-based assays, we
demonstrate that VEGF-E activates key pro-survival pathways in brain
endothelial cells exposed to ischemia/reperfusion-like conditions,
namely extracellular signal-regulated kinase (ERK)1/2 and P38
mitogen-activated protein kinase (MAPK) while preserving the tight
junctions. Importantly, we report that the secretome of VEGF-stimulated
brain endothelial cells improves perivascular cell migration that is
required to mediate the interaction with endothelial cells. Our study
indicates that VEGF-E promotes a stable neovascularization after
ischemic stroke, paving the way to develop new strategies for
therapeutic angiogenesis.