General anaesthesia (GA) during endovascular thrombectomy has been associated with worse patient outcomes in observational studies compared with patients treated without GA. We assessed functional outcome in ischaemic stroke patients with large vessel anterior circulation occlusion undergoing endovascular thrombectomy under GA, versus thrombectomy not under GA (with or without sedation) versus standard care (ie, no thrombectomy), stratified by the use of GA versus standard care. For this meta-analysis, patient-level data were pooled from all patients included in randomised trials in PuMed published between Jan 1, 2010, and May 31, 2017, that compared endovascular thrombectomy predominantly done with stent retrievers with standard care in anterior circulation ischaemic stroke patients (HERMES Collaboration). The primary outcome was functional outcome assessed by ordinal analysis of the modified Rankin scale (mRS) at 90 days in the GA and non-GA subgroups of patients treated with endovascular therapy versus those patients treated with standard care, adjusted for baseline prognostic variables. To account for between-trial variance we used mixed-effects modelling with a random effect for trials incorporated in all models. Bias was assessed using the Cochrane method. The meta-analysis was prospectively designed, but not registered. Seven trials were identified by our search; of 1764 patients included in these trials, 871 were allocated to endovascular thrombectomy and 893 were assigned standard care. After exclusion of 74 patients (72 did not undergo the procedure and two had missing data on anaesthetic strategy), 236 (30%) of 797 patients who had endovascular procedures were treated under GA. At baseline, patients receiving GA were younger and had a shorter delay between stroke onset and randomisation but they had similar pre-treatment clinical severity compared with patients who did not have GA. Endovascular thrombectomy improved functional outcome at 3 months both in patients who had GA (adjusted common odds ratio (cOR) 1·52, 95% CI 1·09-2·11, p=0·014) and in those who did not have GA (adjusted cOR 2·33, 95% CI 1·75-3·10, p<0·0001) versus standard care. However, outcomes were significantly better for patients who did not receive GA versus those who received GA (covariate-adjusted cOR 1·53, 95% CI 1·14-2·04, p=0·0044). The risk of bias and variability between studies was assessed to be low. Worse outcomes after endovascular thrombectomy were associated with GA, after adjustment for baseline prognostic variables. These data support avoidance of GA whenever possible. The procedure did, however, remain effective versus standard care in patients treated under GA, indicating that treatment should not be withheld in those who require anaesthesia for medical reasons. Medtronic.

Direct reprogramming of non-neuronal cells to generate new neurons is a promising approach to repair damaged brains. Impact of the in vivo environment on neuronal reprogramming, however, is poorly understood. Here we show that regional differences and injury conditions have significant influence on the efficacy of reprogramming and subsequent survival of the newly generated neurons in the adult rodent brain. A combination of local exposure to growth factors and retrovirus-mediated overexpression of the neurogenic transcription factor Neurogenin2 can induce new neurons from non-neuronal cells in the adult neocortex and striatum where neuronal turnover is otherwise very limited. These two regions respond to growth factors and Neurogenin2 differently and instruct new neurons to exhibit distinct molecular phenotypes. Moreover, ischaemic insult differentially affects differentiation of new neurons in these regions. These results demonstrate strong environmental impact on direct neuronal reprogramming in vivo.

Tauroursodeoxycholic acid (TUDCA), a hydrophilic bile acid, is a strong modulator of apoptosis in both hepatic and nonhepatic cells, and appears to function by inhibiting mitochondrial membrane perturbation. Excitotoxicity, metabolic compromise, and oxidative stress are major determinants of cell death after brain ischemia-reperfusion injury. However, some neurons undergo delayed cell death that is characteristic of apoptosis. Therefore, the authors examined whether TUDCA could reduce the injury associated with acute stroke in a well-characterized model of transient focal cerebral ischemia. Their model of middle cerebral artery occlusion resulted in marked cell death with prominent terminal deoxynucleotidyl transferase-mediated 2′-deoxyuridine 5′-triphosphate-biotin nick end labeling (TUNEL) within the ischemic penumbra, mitochondrial swelling, and caspase activation. Tauroursodeoxycholic acid administered 1 hour after ischemia resulted in significantly increased bile acid levels in the brain, improved neurologic function, and an approximately 50% reduction in infarct size 2 and 7 days after reperfusion. In addition, TUDCA significantly reduced the number of TUNEL-positive brain cells, mitochondrial swelling, and partially inhibited caspase-3 processing and substrate cleavage. These findings suggest that the mechanism for in vivo neuroprotection by TUDCA is, in part, mediated by inhibition of mitochondrial perturbation and subsequent caspase activation leading to apoptotic cell death. Thus, TUDCA, a clinically safe molecule, may be useful in the treatment of stroke and possibly other apoptosis-associated acute and chronic injuries to the brain.

Neural stem cells (NSCs) reside in widespread regions along the lateral ventricle and generate diverse olfactory bulb (OB) interneuron subtypes in the adult mouse brain. Molecular mechanisms underlying their regional diversity, however, are not well understood. Here we show that the homeodomain transcription factor Gsx2 plays a crucial role in the region-specific control of adult NSCs in both persistent and injury-induced neurogenesis. In the intact brain, Gsx2 is expressed in a regionally restricted subset of NSCs and promotes the activation and lineage progression of stem cells, thereby controlling the production of selective OB neuron subtypes. Moreover, Gsx2 is ectopically induced in damaged brains outside its normal expression domains and is required for injury-induced neurogenesis in the subventricular zone (SVZ). These results demonstrate that mobilization of adult NSCs is controlled in a region-specific manner and that distinct mechanisms operate in continuous and injury-induced neurogenesis in the adult brain.