Vascular endothelial growth factor (VEGF) has previously been shown to display neuroprotective effects following ischemia, suggesting that VEGF may potentially be applied as a neuroprotective agent for the treatment of other neurological diseases. In this study, we investigated the neuroprotective capacity of VEGF in a model of Parkinson's disease. VEGF was found to be neuroprotective against cell death of primary E14 murine ventral mesencephalic neurons induced by 6-hydroxydopamine (6-OHDA) treatment in vitro. Further, rats receiving a continuous infusion of VEGF into the striatum via encapsulated hVEGF-secreting cells (baby hamster kidney-VEGF) displayed a significant decrease in amphetamine-induced rotational behavior and a significant preservation of tyrosine hydroxylase-positive neurons and fibers compared with control animals. VEGF likely functions via direct mechanisms by signaling through the neuropilin receptor expressed upon dopaminergic neurons in response to 6-OHDA treatment. Further, VEGF is likely to promote neuroprotection indirectly by activating the proliferation of glia and by promoting angiogenesis. Our results support a potential neuroprotective role for VEGF in the treatment of Parkinson's disease.

Cell therapy using stem cells is awaited by stroke patients with impaired movement and cognitive functions, although intravenous alteplase-administration ameliorated outcomes of patients receiving the therapy within 3 h of onset. In this study, we explored the therapeutic effects of neural progenitor cells (NPC) upon middle cerebral artery occlusion (MCAO) model of rats with exploration of the differences between adult and embryonic NPCs in therapeutic effects. GFP-labeled adult or embryonic NPCs were transplanted for transient MCAO model of rats at 1h after reperfusion. Rats were examined behaviorally using limb placement test, rotarod test and cylinder test with neuroradiological assessment using magnetic resonance imaging (MRI). Consequently after euthanasia, rats were immunohistochemically investigated to explore graft survival and immune reaction. MRI of rats receiving NPCs revealed significant reduction of infarct volumes, compared to vehicle-treated rats with corresponding behavioral amelioration. The transplanted cells were surviving in rats receiving NPCs, although the number of embryonic NPCs was significantly higher than that of adult NPCs. Iba-1-positive inflammatory cells of rats receiving adult NPCs were prominent, compared to those receiving embryonic NPCs, which might be a rationale for the differences between rats receiving adult and embryonic NPCs in the number of surviving NPCs. On the contraries, adult NPCs surely demonstrated therapeutic effects with a few surviving cells, thus indicating that the therapeutic effects might be due to trophic/growth factor-secretion from transplanted NPCs, rather than replacement of damaged host neurons. Therapeutic effects of NPCs for MCAO model of rats were clarified in this study. Transplantation of NPCs will be a hopeful strategy for stroke patients, although further studies are required for the patient safety and underlying mechanisms.

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Continuous intracerebral administration of low-dose VEGF165 through encapsulated grafts of VEGF-producing cells produces neuroprotective and angiogenic effects. These effects improve subsequent motor function.

These neuroprotective effects may be related to glial proliferation and signaling via the GDNF receptor alpha1. The results of this study support a role for this grafting technique in the treatment of PD.