To observe the effects of neural stem cells (NSCs)
transplantation in rats' striatum and subventricular zone (SVZ) in rat models of focal
cerebral ischemia and reperfusion. Hippocampus was extracted from fetal rats with 14 days of gestation.
Suspension culture was used to isolate and culture the rat's NSCs. A
cerebral ischemia and reperfusion rat's model was made on the left side of the brain through occlusion of the left middle cerebral artery. Neurological signs were assessed by Zea Longa's five-grade scale, with scores 1, 2, and 3 used to determine the successful establishment of the rat's model. The NSCs were stereotaxically injected into the left striatum 24 hours after the successful rat's model was built. Rats were then randomly divided into 5 groups, namely, normal group,
sham operation group,
ischemia group, PBS
transplantation group, and NSCs
transplantation group, each of which was observed on day 3, day 7, and day 14. The
ischemia-related neurological deficits were assessed by using a 7-point evaluation criterion. Forelimb
injuries were evaluated in all rats using the foot-fault approach.
Infarct size changes were observed through TTC staining and cell morphology and structure in the
infarct region were investigated by Nissl staining. Apoptosis and apoptosis-positive cell counts were studied by Tunel assay. Expressions of double-labeling positive cells in the striatum and subventricular zone (SVZ) were observed by
BrdU/NeuN and
BrdU/GFAP fluorescent double-labeling method and the number of positive cells in the striatum and SVZ was counted. Results from the differently treated groups showed that right
hemiplegia occurred in the
ischemia group, PBS
transplantation group, and NSCs
transplantation group in varying degrees. Compared with the former two groups, there was least
hemiplegia in the NSCs
transplantation group. The TTC staining assay showed that rats in the NSCs
transplantation group had smaller
infarct volume than those from the PBS
transplantation group. The Nissl dyeing showed that there was a large area of neuronal
necrosis and apoptosis in the
ischemia and PBS
transplantation groups, and damage was mainly focused in the striatum. Degeneration and damage of nerve cells were significantly reduced in the NSCs
transplantation group. The Tunel assay showed that the number of apoptosis-positive cells in the NSCs
transplantation group was less than that in the PBS
transplantation group at each time point. Double immunofluorescent labeling showed that the proliferation of endogenous neural stem cells began at the third day, reaching the peak at the 7th day, and was significantly reduced at the 14th day in the SVZ. The number of
BrdU/NeuN increased significantly in the NSCs
transplantation group compared to that in the PBS
transplantation group (P < 0.05). The number of
BrdU/GFAP decreased significantly in the NSCs
transplantation group compared to that of PBS
transplantation group (P < 0.05). The number of
BrdU/GFAP-positive cells in the striatum was observed to be much more in the PBS
transplantation group than in the NSCs
transplantation group. Both neurological deficits and coordination capacity of rats with
cerebral ischemia were significantly improved via
transplantation of the neural stem cells. In conclusion,
transplantation of neural stem cells can therefore possibly promote the differentiation of endogenous NSCs into neurons and reduce their differentiation towards glial cells.
Transplantation of the neural stem cells may also change the ischemic microenvironment of striatum, possibly inhibiting the proliferation of glial cells.