Masahiro Kameda

Intravenous administration of mesenchymal stem cells exerts therapeutic effects on parkinsonian model of rats: Focusing on neuroprotective effects of stromal cell-derived factor-1α

BackgroundMesenchymal stem cells (MSCs) are pluripotent stem cells derived from bone marrow with secretory functions of various neurotrophic factors. Stromal cell-derived factor-1α (SDF-1α) is also reported as one of chemokines released from MSCs. In this research, the therapeutic effects of MSCs through SDF-1α were explored. 6-hydroxydopamine (6-OHDA, 20 μg) was injected into the right striatum of female SD rats with subsequent administration of GFP-labeled MSCs, fibroblasts, (i.v., 1 × 107 cells, respectively) or PBS at 2 hours after 6-OHDA injection. All rats were evaluated behaviorally with cylinder test and amphetamine-induced rotation test for 1 month with consequent euthanasia for immunohistochemical evaluations. Additionally, to explore the underlying mechanisms, neuroprotective effects of SDF-1α were explored using 6-OHDA-exposed PC12 cells by using dopamine (DA) assay and TdT-mediated dUTP-biotin nick-end labeling (TUNEL) staining.ResultsRats receiving MSC transplantation significantly ameliorated behaviorally both in cylinder test and amphetamine-induced rotation test compared with the control groups. Correspondingly, rats with MSCs displayed significant preservation in the density of tyrosine hydroxylase (TH)-positive fibers in the striatum and the number of TH-positive neurons in the substantia nigra pars compacta (SNc) compared to that of control rats. In the in vitro study, SDF-1α treatment increased DA release and suppressed cell death induced by 6-OHDA administration compared with the control groups.ConclusionsConsequently, MSC transplantation might exert neuroprotection on 6-OHDA-exposed dopaminergic neurons at least partly through anti-apoptotic effects of SDF-1α. The results demonstrate the potentials of intravenous MSC administration for clinical applications, although further explorations are required.

Neurorescue effects of VEGF on a rat model of Parkinson's disease

Vascular endothelial growth factor (VEGF) has been shown to display neuroprotective effects on dopaminergic (DA) neurons. Here, we investigated the neurorescue effects of VEGF on 6-hydroxydopamine (6-OHDA)-treated DA neurons in vitro and in vivo. Initially, we examined in vitro whether 1, 10, or 100 ng/ml of VEGF administration at 2 or 4 h after 6-OHDA treatment rescued DA neurons derived from E14 murine ventral mesencephalon. The earlier treatment of VEGF suppressed 6-OHDA-induced loss of DA neurons more than the delayed treatment. Next, we examined whether the continuous infusion of VEGF had neurorescue effects in a rat model of Parkinsons disease. We established a human VEGF secreting cell line (BHK-VEGF) and encapsulated the cells into hollow fibers. The encapsulated cells were unilaterally transplanted into the striatum of adult rats at 1 or 2 weeks after 6-OHDA lesions, and animals subsequently underwent behavioral and immunohistochemical evaluations. Compared to lesioned rats that received BHK-Control capsules, lesioned rats transplanted with BHK-VEGF capsules showed a significant reduction in the number of amphetamine-induced rotations, a significant preservation of TH-positive neurons in the substantia nigra pars compacta, and a remarkable glial proliferation in the striatum, with the earlier transplantation exerting much more benefits than the delayed transplantation. Parallel studies revealed that the observed in vitro and in vivo neurorescue effects were likely mediated by VEGFs angiogenic and glial proliferative effects, as well as its direct effects on the neurons. Our results suggest that VEGF is a highly potent neurorescue molecule for Parkinsons disease therapy.

Embryonic neural stem cells transplanted in middle cerebral artery occlusion model of rats demonstrated potent therapeutic effects, compared to adult neural stem cells

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.

Electrical Stimulation of the Cerebral Cortex Exerts Antiapoptotic, Angiogenic, and Anti-Inflammatory Effects in Ischemic Stroke Rats Through Phosphoinositide 3-Kinase/Akt Signaling Pathway

Background and Purpose— Neuroprotective effects of electric stimulation have been recently shown in ischemic stroke, but the underlying mechanisms remain poorly understood. Methods— Adult Wistar rats weighing 200 to 250 g received occlusion of the right middle cerebral artery for 90 minutes. At 1 hour after reperfusion, electrodes were implanted to rats on the right frontal epidural space. Electric stimulation, at preset current (0 to 200 &mgr;A) and frequency (0 to 50 Hz), was performed for 1 week. Stroke animals were subjected to behavioral tests at 3 days and 1 week postmiddle cerebral artery and then immediately euthanized for protein and immunohistochemical assays. After demonstration of behavioral and histological benefits, subsequent experiments pursued the mechanistic hypothesis that electric stimulation exerted antiapoptotic effects through the phosphoinositide 3-kinase-dependent pathway; thus, cortical stimulation was performed in the presence or absence of specific inhibitors of phosphoinositide 3-kinase (LY294002) in stroke rats. Results— Cortical stimulation abrogated the ischemia-associated increase in apoptotic cells in the injured cortex by activating antiapoptotic cascades, which was reversed by the phosphoinositide 3-kinase inhibitor LY294002 as reflected behaviorally and immunohistochemically. Furthermore, brain levels of neurotrophic factors (glial cell line-derived neurotrophic factor, brain-derived neurotrophic factor, vascular endothelial growth factor) were upregulated, which coincided with enhanced angiogenesis and suppressed proliferation of inflammatory cells in the ischemic cortex. Conclusions— These results suggest that electric stimulation prevents apoptosis through the phosphoinositide 3-kinase pathway. Consequently, the ischemic brain might have been rendered as a nurturing microenvironment characterized by robust angiogenesis and diminished microglial/astrocytic proliferation, resulting in the reduction of infarct volumes and behavioral recovery. Electric stimulation is a novel and potent therapeutic tool for cerebral ischemia.

Adult neural stem and progenitor cells modified to secrete GDNF can protect, migrate and integrate after intracerebral transplantation in rats with transient forebrain ischemia

Adult neural stem and progenitor cells (NSPCs) are important autologous transplantation tools in regenerative medicine, as they can secrete factors that protect the ischemic brain. We investigated whether adult NSPCs genetically modified to secrete more glial cell line‐derived neurotrophic factor (GDNF) could protect against transient ischemia in rats. NSPCs were harvested from the subventricular zone of adult Wistar rats and cultured for 3 weeks in the presence of epidermal growth factor. The NSPCs were treated with fibre‐mutant Arg‐Gly‐Asp adenovirus containing the GDNF gene (NSPC‐GDNF) or enhanced green fluorescent protein (EGFP) gene (NSPC‐EGFP; control group). In one experiment, cultured cells were transplanted into the right ischemic boundary zone of Wistar rat brains. One week later, animals underwent 90 min of intraluminal right middle cerebral artery occlusion followed by magnetic resonance imaging and behavioural tests. The NSPC‐GDNF group had higher behavioural scores and lesser infarct volume than did controls at 1, 7 and 28 days postocclusion. In the second experiment, we transplanted NSPCs 3 h after ischemic insult. Compared to controls, rats receiving NSPC‐GDNF had decreased infarct volume and better behavioural assessments at 7 days post‐transplant. Animals were killed on day 7 and brains were collected for GDNF ELISA and morphological assessment. Compared to controls, more GDNF was secreted, more NSPC‐GDNF cells migrated toward the ischemic core and more NSPC‐GDNF cells expressed immature neuronal marker. Moreover, the NSPC‐GDNF group showed more effective inhibition of microglial invasion and apoptosis. These findings suggest that NSPC‐GDNF may be useful in treatment of cerebral ischemia.

The differences between high and low-dose administration of VEGF to dopaminergic neurons of in vitro and in vivo Parkinson's disease model

Vascular endothelial growth factor (VEGF) has previously been shown to display neuroprotective effects on dopaminergic (DA) neurons. In this study, we investigated whether the effects of VEGF were dose-dependent or not. First, VEGF was shown to be neuroprotective on 6-hydroxydopamine (6-OHDA)-treated murine DA neurons in vitro, although the 1 ng/ml of VEGF displayed more neuroprotective effects than 100 ng/ml. Furthermore, using 2 sizes of capsules (small/large) with different secreting quantities, 6-OHDA-treated rats receiving the small capsule filled with VEGF-secreting cells (BHK-VEGF) into the striatum showed a significant decrease in amphetamine-induced rotational behavior in number and a significant preservation of TH-positive fibers compared to those receiving the large BHK-VEGF capsule as well as those receiving BHK-Control capsule. Rats receiving the large BHK-VEGF capsule showed much more glial proliferation, angiogenesis, and brain edema around the capsule than those with the small one. High-dose administration of VEGF might cause poor circulation related to brain edema, although low-dose administration of VEGF displays neuroprotective effects on DA neurons. Our results demonstrate the importance of administration dose of VEGF, suggesting that low-dose administration of VEGF might be desirable for Parkinsons disease.

Neuroprotective effects of edaravone-administration on 6-OHDA-treated dopaminergic neurons

BackgroundParkinsons disease (PD) is a neurological disorder characterized by the degeneration of nigrostriatal dopaminergic systems. Free radicals induced by oxidative stress are involved in the mechanisms of cell death in PD. This study clarifies the neuroprotective effects of edaravone (MCI-186, 3-methyl-1-phenyl-2-pyrazolin-5-one), which has already been used for the treatment of cerebral ischemia in Japan, on TH-positive dopaminergic neurons using PD model both in vitro and in vivo. 6-hydroxydopamine (6-OHDA), a neurotoxin for dopaminergic neurons, was added to cultured dopaminergic neurons derived from murine embryonal ventral mesencephalon with subsequet administration of edaravone or saline. The number of surviving TH-positive neurons and the degree of cell damage induced by free radicals were analyzed. In parallel, edaravone or saline was intravenously administered for PD model of rats receiving intrastriatal 6-OHDA lesion with subsequent behavioral and histological analyses.ResultsIn vitro study showed that edaravone significantly ameliorated the survival of TH-positive neurons in a dose-responsive manner. The number of apoptotic cells and HEt-positive cells significantly decreased, thus indicating that the neuroprotective effects of edaravone might be mediated by anti-apoptotic effects through the suppression of free radicals by edaravone. In vivo study demonstrated that edaravone-administration at 30 minutes after 6-OHDA lesion reduced the number of amphetamine-induced rotations significantly than edaravone-administration at 24 hours. Tyrosine hydroxylase (TH) staining of the striatum and substantia nigra pars compacta revealed that edaravone might exert neuroprotective effects on nigrostriatal dopaminergic systems. The neuroprotective effects were prominent when edaravone was administered early and in high concentration. TUNEL, HEt and Iba-1 staining in vivo might demonstrate the involvement of anti-apoptotic, anti-oxidative and anti-inflammatory effects of edaravone-administration.ConclusionEdaravone exerts neuroprotective effects on PD model both in vitro and in vivo. The underlying mechanisms might be involved in the anti-apoptotic effects, anti-oxidative effects, and/or anti-inflammatory effects of edaravone. Edaravone might be a hopeful therapeutic option for PD, although the high therapeutic dosage remains to be solved for the clinical application.

Neuroprotective effects of liraglutide for stroke model of rats

The number of diabetes mellitus (DM) patients is increasing, and stroke is deeply associated with DM. Recently, neuroprotective effects of glucagon-like peptide-1 (GLP-1) are reported. In this study, we explored whether liraglutide, a GLP-1 analogue exerts therapeutic effects on a rat stroke model. Wistar rats received occlusion of the middle cerebral artery for 90 min. At one hour after reperfusion, liraglutide or saline was administered intraperitoneally. Modified Bederson’s test was performed at 1 and 24 h and, subsequently, rats were euthanized for histological investigation. Peripheral blood was obtained for measurement of blood glucose level and evaluation of oxidative stress. Brain tissues were collected to evaluate the level of vascular endothelial growth factor (VEGF). The behavioral scores of liraglutide-treated rats were significantly better than those of control rats. Infarct volumes of liraglutide-treated rats at were reduced, compared with those of control rats. The level of derivatives of reactive oxygen metabolite was lower in liraglutide-treated rats. VEGF level of liraglutide-treated rats in the cortex, but not in the striatum significantly increased, compared to that of control rats. In conclusion, this is the first study to demonstrate neuroprotective effects of liraglutide on cerebral ischemia through anti-oxidative effects and VEGF upregulation.

The high integration and differentiation potential of autologous neural stem cell transplantation compared with allogeneic transplantation in adult rat hippocampus

Cell therapy is thought to have a central role in restorative therapy, which aims to restore function to the damaged nervous system. The purpose of this study was to establish an autologous neural stem cell (NSC) transplantation model using adult rats and to compare survival, migration, and differentiation between this system and allogeneic NSC transplantation. Furthermore, we compared the immunologic response of the host tissue between autologous and allogeneic transplantation. NSCs were removed from the subventricular zone of adult Fischer 344 rats using stereotactic methods. NSCs were expanded and microinjected into normal hippocampus in the autologous brain. Allogeneic NSC (derived from adult Wistar rats) transplantation was performed using the same procedure, and hippocampal sections were analyzed immunohistologically 3 weeks post-transplantation. The cell survival and migration rate were higher for autologous transplantation than for allogeneic transplantation, and the neuronal differentiation rate in the autologous transplanted cells far exceeded that of allogeneic transplantation. Furthermore, there was less astrocyte and microglia reactivity in the host tissue of the autologous transplantation compared with allogeneic transplantation. These findings demonstrate that immunoreactivity of the host tissue strongly influences cell transplantation in the CNS as the autologous transplantation did not induce host tissue immunoreactivity; the microenvironment was essentially maintained in an optimal condition for the transplanted cells.

Comparison of the therapeutic potential of adult and embryonic neural precursor cells in a rat model of Parkinson disease.

OBJECTIVES The therapeutic effects of adult and embryonic neural precursor cells (NPCs) were evaluated and their therapeutic potential compared in a rat model of Parkinson disease. METHODS Adult NPCs were obtained from the subventricular zone and embryonic NPCs were taken from the ganglionic eminence of 14-day-old embryos. Each NPC type was cultured with epidermal growth factor. The in vitro neuronal differentiation rate of adult NPCs was approximately equivalent to that of embryonic NPCs after two passages. Next, the NPCs were transfected with either green fluorescent protein or glial cell line-derived neurotrophic factor (GDNF) by adenoviral infection and transplanted into the striata in a rat model of Parkinson disease (PD) induced by unilateral intrastriatal injection of 6-hydroxydopamine. An amphetamine-induced rotation test was used to evaluate rat behavioral improvement, and immunohistochemical analysis was performed to compare grafted cell survival, differentiation, and host tissue changes. RESULTS The rats with GDNF-transfected NPCs had significantly fewer amphetamine-induced rotations and less histological damage. Except for the proportion of surviving grafted cells, there were no significant differences between adult and embryonic NPCs. CONCLUSIONS Adult and embryonic NPCs have a comparable therapeutic potential in a rat model of PD.