Minocycline-Preconditioned Neural Stem Cells Enhance Neuroprotection after Ischemic Stroke in Rats

Abstract

Transplantation of neural stem cells (NSCs) offers a novel therapeutic strategy for stroke; however, massive grafted-cell death following transplantation, possibly due to a hostile host-brain environment, lessens the effectiveness of this approach. Here, we have investigated whether reprogramming NSCs with minocycline, a broadly-used antibiotic also known to possess cytoprotective properties, enhances survival of grafted cells and promotes neuroprotection in ischemic stroke. NSCs harvested from the subventricular zone of fetal rats were preconditioned with minocycline in vitro and transplanted into rat brains 6 h after transient middle cerebral artery occlusion. Histological and behavioral tests were examined from days 0–28 after stroke. For in vitro experiments, NSCs were subjected to oxygen-glucose deprivation and reoxygenation. Cell viability and antioxidant gene expression were analyzed. Minocycline preconditioning protected the grafted NSCs from ischemic reperfusion injury via up-regulation of Nrf2 and Nrf2-regulated antioxidant genes. Additionally, preconditioning with minocycline induced the NSCs to release paracrine factors, including brain-derived neurotrophic factor, nerve growth factor, glial cell-derived neurotrophic factor, and vascular endothelial growth factor. Moreover, transplantation of the minocycline-preconditioned NSCs significantly attenuated infarct size and improved neurological performance, compared with non-preconditioned NSCs. Minocycline-induced neuroprotection was abolished by transfecting the NSCs with Nrf2-small interfering RNA before transplantation. Thus, preconditioning with minocycline, which reprograms NSCs to tolerate oxidative stress after ischemic reperfusion injury and to express higher levels of paracrine factors through Nrf2 up-regulation, is a simple and safe approach to enhance the effectiveness of transplantation therapy in ischemic stroke.

Transplantation of Neural Stem Cells That Overexpress Sod1 Enhances Amelioration of Intracerebral Hemorrhage in Mice

“…30,31 We recently showed that ROS production resulted in a reduction in grafted cells and diminishment of cell transplantation therapy for ischemic stroke. 15,19,21 Similarly, in the present study, we showed that ROS induced by Hb accelerated NSC death. Hydroethidine staining was enhanced in WT NSCs that were treated with Hb, whereas it was reduced in SOD1 Tg NSCs exposed to Hb.…”

CDK5 knockdown in astrocytes provide neuroprotection as a trophic source via Rac1

“…Our findings are controversial because they show that CDK5 knockdown in astrocytes protects neurons and astrocytes against glioand excitotoxicity, suggesting a differential mechanism of CDK5 in the excitotoxic and oxidative insults, that may involve trophic factors or that the role of CDK5 is dependent on the severity of Ca 2+ overload. Nfr2 and trophic factors (BDNF, GDNF, VEGF, NGF) show neuroprotection effects (Kam et al, 2011;Sakata et al, 2012), however the specific mechanism involving the ability of Nrf2 and BDNF to protect remains unclear. Approximations using Nrf2 knockout mice show that Nfr2 deficiency decreases BDNF levels (Mendez-David et al, 2015).…”

Applications of the Keap1–Nrf2 system for gene and cell therapy

“…For example, preconditioning of NSCs with minocycline, a broadly used cytoprotective tetracycline, promotes the effectiveness of transplantation therapy through induction of Nrf2 [193] . Preconditioning for 24 h with minocycline was shown to protect grafted stem cells from ischemic reperfusion injury through induction of Nrf2-target genes and increased expression of paracrine factors controlled by Nrf2 and HO-1.…”