Objective: To detect the expression and the role of vascular endothelial growth factor (VEGF)-transfected neural stem cells (NSCs) in rat brain subjected to ischemia.
Methods: Fetal NSCs were cultured from E14 days SD rats and transfected with VEGF121 gene by using lipofectAMINE technique. The gene expression of transfected cells was detected by RT-PCR and immunofluorescent staining in vitro. Temporary middle cerebral artery occlusion (tMCAO) model was established in 40 SD rats and then rate were randomly divided into (1) control group (n = 10), (2) PBS transplantation group (n = 10), (3) neural stem cells transplantation group (n = 10), and (4) VEGF-secreting neural stem cells transplantation group (n = 10). BrdU-labelled NSCs and VEGF-secreting NSCs were transplanted into the penumbra zones respectively 3 days after the tMCAO model was established. Neurological Severity Score (NSS) was checked in all groups 2, 4, 6, 8, 10, 12 weeks respectively after transplantation. One and 12 weeks after the transplantation, 10 rats in the group (4) were killed and then brains taken out respectively. By using immunofluorescent staining, the VEGF expression of transplanted cells 1 week after transplantation, differentiation and migration of transplanted neural stem cells 12 week after transplantation were detected respectively.
Results: VEGF-transfected neural stem cells could continuously express gene products during the first 2 weeks. Both transfected NSCs and their progeny expressed VEGF gene products, which was demonstrated by fluorescence study. There were no significant differences in NSS in groups 4 when tMCAO models were just established. However, the values of NSS in (4) group were 5.8 +/- 1.5, 5.0 +/- 1.0, 4.6 +/- 1.0, 4.0 +/- 0.7, 4.0 +/- 1.0, 3.8 +/- 0.4 from 2 approximately 12 weeks after transplantation, significantly lower than those in groups (1) and (2) 8 weeks (P = 0.008) and those in groups (1), (2) and (3) 12 weeks (P = 0.000) after transplantation. NSS in group (3) was also lower than that in groups (1) and (2) 8 and 12 weeks after transplantation. One week after transplantation, immunofluorescent staining showed that VEGF-transfected NSCs migrated and expressed VEGF into hosts' brains. Twelve weeks after transplantation, transplanted NSCs survived and migrated, some of them differentiated to neurons and integrated well with hosts' cytoarchitectural components.
Conclusion: VEGF-transfected NSCs express gene products during the early time after transplantation, which reduce brain injury through protecting the vascular system against ischemia and reperfusion injury. Transplantation of VEGF-transfected NSCs might be a novel method for treatment of cerebral ischemia.