Very Low Efficiency of Direct Reprogramming of Astrocytes Into Neurons in the Brains of Young and Aged Mice After Cerebral Ischemia

Abstract

After cerebral ischemia, the ratio between astroglial cells and neurons in the neurovascular unit is disrupted in the perilesional area. We hypothesized that restoring the balance within the neurovascular unit may lead to an improved neurorestoration after focal ischemia. Recently, an innovative technology has been invented to efficiently convert proliferating astroglial cells into neurons in the injured young brain. However, the conversion efficacy of this technology has not been explored in the post-stroke brains of the aged rodents. To this end, we used a retroviral delivery system encoding the transcription factor Ngn2 alone or in combination with the antiapoptotic factor Bcl-2 to target proliferating astrocytes in the neocortex of young and aged mice after cerebral ischemia. Successful direct in vivo reprogramming of reactive glia into neuroblasts and mature neurons was assessed by cellular phenotyping. We found that the conversion efficacy of proliferating astrocytes into neurons after cerebral ischemia in young and aged mice is disappointingly low, most likely because the therapeutic vectors carrying the conversion gene are engulfed by phagocytes shortly after intracortical administration. We conclude that other viral vectors and combinations of transcription factors should be employed to improve the efficacy of glia-to-neuron conversion after stroke in young and aged rodents.

Conversion of Reactive Astrocytes to Induced Neurons Enhances Neuronal Repair and Functional Recovery After Ischemic Stroke

“…Concurrently, the specificity, reliability, and clinical potential of this novel regenerative gene therapy have sparked much debate. Investigations spanning various routes of administration and in animal models across the lifespan have yielded inconsistent results (Gresita et al, 2019 ). Our investigation examined the viability of reprogramming of astrocytes in vitro and in vivo .…”

Induced Neurons for Disease Modeling and Repair: A Focus on Non-fibroblastic Cell Sources in Direct Reprogramming

“…While there has been evidence of success, some studies have reinforced the need for more effective administration strategies. One study reported low efficacy of direct reprogramming of astrocytes to iN post stroke in aged mice (Gresita et al, 2019). Researchers hypothesized that the therapeutic vectors carrying the conversion gene were phagocytosed rapidly by microglia after administration (Gresita et al, 2019).…”

“…One study reported low efficacy of direct reprogramming of astrocytes to iN post stroke in aged mice (Gresita et al, 2019). Researchers hypothesized that the therapeutic vectors carrying the conversion gene were phagocytosed rapidly by microglia after administration (Gresita et al, 2019). One noteworthy method used protein transduction domains fused to transcription factors to deliver proneural transcription factors to astrocytes (Robinson et al, 2018).…”

Tanshinone IIA alleviates the damage of neurocytes by targeting GLUT1 in ischaemia reperfusion model (in vivo and in vitro experiments)

“…The mice were first anaesthetised with 100 mg/kg ketamine and 10 mg/kg xylazine and placed on a stereotaxic device. Then, the middle cerebral artery (MCA) was exposed and occluded with a soldering iron placed directly on the dura [16]. After surgery, the soft tissues were replaced and the skin was closed using 5-0 nylon suture.…”