An antioxidant and anti-ER stress combination therapy elevates phosphorylation of α-Syn at serine 129 and alleviates post-TBI PD-like pathology in a sex-specific manner in mice.

Clinical studies have shown that traumatic brain injury (TBI) increases the onset of Parkinson's disease (PD) in later life by >50%. Oxidative stress, endoplasmic reticulum (ER) stress, and inflammation are the major drivers of both TBI and PD pathologies. We presently evaluated if curtailing oxidative stress and ER stress concomitantly using a combination of apocynin and tert-butylhydroquinone and salubrinal during the acute stage after TBI in mice reduces the severity of late-onset PD-like pathology. The effect of multiple low doses of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on post-TBI neurodegeneration was also evaluated. The combo therapy elevated the level of phosphorylation at serine 129 (pS129) of α-Syn in the pericontusional cortex of male mice at 72 h post-TBI. Motor and cognitive deficits induced by TBI lasted at least 3 months and the combo therapy curtailed these deficits in both sexes. At 3 months post-TBI, male mice given combo therapy exhibited significantly lesser α-Syn aggregates in the SN and higher TH+ cells in the SNpc, compared to vehicle control. However, the aggregate number was not significantly different between groups of female mice. Moreover, TBI-induced loss of TH+ cells was negligible in female mice irrespective of treatment. The MPTP treatment aggravated PD-like pathology in male mice but had a negligible effect on the loss of TH+ cells in female mice. Thus, the present study indicates that mitigation of TBI-induced oxidative stress and ER stress at the acute stage could potentially reduce the risk of post-TBI PD-like pathology at least in male mice, plausibly by elevating pS129-α-Syn level.

Non-pharmacological interventions for traumatic brain injury.

Heterogeneity and variability of symptoms due to the type, site, age, sex, and severity of injury make each case of traumatic brain injury (TBI) unique. Considering this, a universal treatment strategy may not be fruitful in managing outcomes after TBI. Most of the pharmacological therapies for TBI aim at modifying a particular pathway or molecular process in the sequelae of secondary injury rather than a holistic approach. On the other hand, non-pharmacological interventions such as hypothermia, hyperbaric oxygen, preconditioning with dietary adaptations, exercise, environmental enrichment, deep brain stimulation, decompressive craniectomy, probiotic use, gene therapy, music therapy, and stem cell therapy can promote healing by modulating multiple neuroprotective mechanisms. In this review, we discussed the major non-pharmacological interventions that are being tested in animal models of TBI as well as in clinical trials. We evaluated the functional outcomes of various interventions with an emphasis on the links between molecular mechanisms and outcomes after TBI.

Role of transcription factors, noncoding RNAs, epitranscriptomics, and epigenetics in post-ischemic neuroinflammation.

Post-stroke neuroinflammation is pivotal in brain repair, yet persistent inflammation can aggravate ischemic brain damage and hamper recovery. Following stroke, specific molecules released from brain cells attract and activate central and peripheral immune cells. These immune cells subsequently release diverse inflammatory molecules within the ischemic brain, initiating a sequence of events, including activation of transcription factors in different brain cell types that modulate gene expression and influence outcomes; the interactive action of various noncoding RNAs (ncRNAs) to regulate multiple biological processes including inflammation, epitranscriptomic RNA modification that controls RNA processing, stability, and translation; and epigenetic changes including DNA methylation, hydroxymethylation, and histone modifications crucial in managing the genic response to stroke. Interactions among these events further affect post-stroke inflammation and shape the depth of ischemic brain damage and functional outcomes. We highlighted these aspects of neuroinflammation in this review and postulate that deciphering these mechanisms is pivotal for identifying therapeutic targets to alleviate post-stroke dysfunction and enhance recovery.

Post-stroke brain can be protected by modulating the lncRNA FosDT.

We previously showed that knockdown or deletion of Fos downstream transcript (FosDT; a stroke-induced brain-specific long noncoding RNA) is neuroprotective. We presently tested the therapeutic potential of FosDT siRNA in rodents subjected to transient middle cerebral artery occlusion (MCAO) using the Stroke Treatment Academic Industry Roundtable criteria, including sex, age, species, and comorbidity. FosDT siRNA (IV) given at 30 min of reperfusion significantly improved motor function recovery (rotarod test, beam walk test, and adhesive removal test) and reduced infarct size in adult and aged spontaneously hypertensive rats of both sexes. FosDT siRNA administered in a delayed fashion (3.5 h of reperfusion following 1 h transient MCAO) also significantly improved motor function recovery and decreased infarct volume. Furthermore, FosDT siRNA enhanced post-stroke functional recovery in normal and diabetic mice. Mechanistically, FosDT triggered post-ischemic neuronal damage via the transcription factor REST as REST siRNA mitigated the enhanced functional outcome in FosDT-/- rats. Additionally, NF-κB regulated FosDT expression as NF-κB inhibitor BAY 11-7082 significantly decreased post-ischemic FosDT induction. Thus, FosDT is a promising target with a favorable therapeutic window to mitigate secondary brain damage and facilitate recovery after stroke regardless of sex, age, species, and comorbidity.

Therapeutic Potential of Intravenous miR-21 Mimic after Stroke Following STAIR Criteria.

The microRNA-21 (miR-21) levels in the brain are crucial in determining post-stroke brain damage and recovery. The miR-21 exerts neuroprotection by targeting mRNAs that translate proteins that mediate brain damage. We currently determined the efficacy and efficiency of intravenously administered miR-21 mimic after focal cerebral ischemia in mice. Adult male mice were intravenously administered with either control mimic or miR-21 mimic at 5 min/2 h after reperfusion following 1 h transient middle cerebral artery occlusion to determine the therapeutic window of miR-21 mimic. Adult female, type-2 diabetic male, aged male, and aged female mice were administered with control/miR-21 mimic at 5 min after reperfusion following 35 min/1 h transient middle cerebral artery occlusion. Early administration of miR-21 mimic significantly reduced brain damage and promoted long-term recovery after stroke. Further, miR-21 mimic is more effective in males than in females subjected to stroke. However, delayed treatment with miR-21 mimic is not efficacious, and type-2 diabetic subjects show no improvement with miR-21 mimic treatment.

Post-stroke depression: epigenetic and epitranscriptomic modifications and their interplay with gut microbiota.

Epigenetic and epitranscriptomic modifications that regulate physiological processes of an organism at the DNA and RNA levels, respectively, are novel therapeutic candidates for various neurological diseases. Gut microbiota and its metabolites are known to modulate DNA methylation and histone modifications (epigenetics), as well as RNA methylation especially N6-methyladenosine (epitranscriptomics). As gut microbiota as well as these modifications are highly dynamic across the lifespan of an organism, they are implicated in the pathogenesis of stroke and depression. The lack of specific therapeutic interventions for managing post-stroke depression emphasizes the need to identify novel molecular targets. This review highlights the interaction between the gut microbiota and epigenetic/epitranscriptomic pathways and their interplay in modulating candidate genes that are involved in post-stroke depression. This review further focuses on the three candidates, including brain-derived neurotrophic factor, ten-eleven translocation family proteins, and fat mass and obesity-associated protein based on their prevalence and pathoetiologic role in post-stroke depression.

Immunomodulatory role of glycoRNAs in the brain.

Glycosylation of lipids and proteins significantly increases the molecular diversity in the brain. Membrane-localized glycoconjugates facilitate critical neuro-immune interactions. Therefore, glycodysregulation is increasingly recognized as a novel hallmark of various acute and chronic neurological diseases. Although RNAs are heavily modified, they are never thought to be substrates for glycosylation due to their inaccessibility to the glycosylation machinery in the Golgi apparatus. The astonishing discovery of cell surface glycoRNAs opened new avenues for glycomedicine. This review highlighted the key features of GlycoRNAs and further discussed their potential immunomodulatory role in the brain, particularly focusing on post-stroke neuroinflammation.

CDR1as regulates α-synuclein-mediated ischemic brain damage by controlling miR-7 availability.

Transient focal ischemia decreased microRNA-7 (miR-7) levels, leading to derepression of its major target α-synuclein (α-Syn) that promotes secondary brain damage. Circular RNA CDR1as is known to regulate miR-7 abundance and function. Hence, we currently evaluated its functional significance after focal ischemia. Transient middle cerebral artery occlusion (MCAO) in adult mice significantly downregulated both CDR1as and miR-7 levels in the peri-infarct cortex between 3 and 72 h of reperfusion. Interestingly, neither pri-miR-7a nor 7b was altered in the ischemic brain. Intracerebral injection of an AAV9 vector containing a CDR1as gene significantly increased CDR1as levels by 21 days that persisted up to 4 months without inducing any observable toxicity in both sham and MCAO groups. Following transient MCAO, there was a significant increase in miR-7 levels and CDR1as binding to Ago2/miR-7 in the peri-infarct cortex of AAV9-CDR1as cohort compared with AAV9-Control cohort at 1 day of reperfusion. CDR1as overexpression significantly suppressed post-stroke α-Syn protein induction, promoted motor function recovery, decreased infarct size, and curtailed the markers of apoptosis, autophagy mitochondrial fragmentation, and inflammation in the post-stroke brain compared with AAV9-Control-treated cohort. Overall, our findings imply that CDR1as reconstitution is neuroprotective after stroke, probably by protecting miR-7 and preventing α-Syn-mediated neuronal death.

Gene Silencing in the Brain with siRNA to Promote Long-Term Post-Stroke Recovery.

RNA interference is a promising strategy to degrade target RNAs of interest after stroke using small interfering RNA (siRNA). An optimized targeting such as combining a siRNA with a nontoxic transfection reagent that facilitates the effective delivery of siRNAs to the brain and subsequent cellular uptake after stroke is needed. Furthermore, an appropriate route of administration such as intravenous (tail vein or retro-orbital sinus) or cerebroventricular injection has to be used. Using siRNAs tagged with fluorescent probes shows the cellular uptake of siRNA. Efficacy and window of opportunity for a siRNA needs to be determined by testing multiple doses and time frame that alters the long-term functional outcomes. Real-time PCR/western blots can be used to determine the siRNA efficiency by evaluating the knockdown of the RNA/protein of interest. In siRNA studies, it is also essential to identify a proper dose (efficacious, but not toxic) by histopathologic testing to identify any toxicity in the peripheral organs and CNS. This chapter describes the strategies to deliver siRNAs to treat stroke and to facilitate post-stroke long-term recovery.

Tau and GSK-3ß are Critical Contributors to α-Synuclein-Mediated Post-Stroke Brain Damage.

Post-stroke secondary brain damage is significantly influenced by the induction and accumulation of α-Synuclein (α-Syn). α-Syn-positive inclusions are often present in tauopathies and elevated tau levels and phosphorylation promotes neurodegeneration. Glycogen synthase kinase 3ß (GSK-3ß) is a known promoter of tau phosphorylation. We currently evaluated the interaction of α-Syn with GSK-3ß and tau in post-ischemic mouse brain. Transient focal ischemia led to increased cerebral protein-protein interaction of α-Syn with both GSK-3ß and tau and elevated tau phosphorylation. Treatment with a GSK-3ß inhibitor prevented post-ischemic tau phosphorylation. Furthermore, α-Syn interaction was observed to be crucial for post-ischemic GSK-3ß-dependent tau hyperphosphorylation as it was not seen in α-Syn knockout mice. Moreover, tau knockout mice show significantly smaller brain damage after transient focal ischemia. Overall, the present study indicates that GSK-3ß catalyzes the α-Syn-dependent tau phosphorylation and preventing this interaction is crucial to limit post-ischemic secondary brain damage.

Cerebroprotective Role of N6-Methyladenosine Demethylase FTO (Fat Mass and Obesity-Associated Protein) After Experimental Stroke.

BACKGROUND: FTO (fat mass and obesity-associated protein) demethylates N6-methyladenosine (m6A), which is a critical epitranscriptomic regulator of neuronal function. We previously reported that ischemic stroke induces m6A hypermethylation with a simultaneous decrease in FTO expression in neurons. Currently, we evaluated the functional significance of restoring FTO with an adeno-associated virus 9, and thus reducing m6A methylation in poststroke brain damage. METHODS: Adult male and female C57BL/6J mice were injected with FTO adeno-associated virus 9 (intracerebral) at 21 days prior to inducing transient middle cerebral artery occlusion. Poststroke brain damage (infarction, atrophy, and white matter integrity) and neurobehavioral deficits (motor function, cognition, depression, and anxiety-like behaviors) were evaluated between days 1 and 28 of reperfusion. RESULTS: FTO overexpression significantly decreased the poststroke m6A hypermethylation. More importantly, exogenous FTO substantially decreased poststroke gray and white matter damage and improved motor function recovery, cognition, and depression-like behavior in both sexes. CONCLUSIONS: These results demonstrate that FTO-dependent m6A demethylation minimizes long-term sequelae of stroke independent of sex.

Dysregulation of the Epitranscriptomic Mark m1A in Ischemic Stroke.

Methylation of adenosine at N1 position yields N1-methyladenosine (m1A), which is an epitranscriptomic modification that regulates mRNA metabolism. Recent studies showed that altered m1A methylation promotes acute and chronic neurological diseases. We currently evaluated the effect of focal ischemia on cerebral m1A methylome and its machinery. Adult male C57BL/6J mice were subjected to transient middle cerebral artery occlusion, and the peri-infarct cortex was analyzed at 12 h and 24 h of reperfusion. The bulk abundance of m1A was measured by mass spectrometry and dot blot, and transcriptome-wide m1A alterations were profiled using antibody-independent m1A-quant-seq. Expression of the m1A writers and erasers was estimated by real-time PCR. Ischemia significantly decreased m1A levels and concomitantly upregulated m1A demethylase alkB homolog 3 at 24 h of reperfusion compared to sham. Transcriptome-wide profiling showed differential m1A methylation at 14 sites (8 were hypo- and 6 were hypermethylated). Many of those are located in the 3'-UTRs of unannotated transcripts proximal to the genes involved in regulating protein complex assembly, circadian rhythms, chromatin remodeling, and chromosome organization. Using several different approaches, we show for the first time that m1A epitranscriptomic modification in RNA is highly sensitive to cerebral ischemia.

MicroRNA miR-7 Is Essential for Post-stroke Functional Recovery.

Transient focal ischemia induces a sustained downregulation of miR-7 leading to derepression of its target α-synuclein (α-Syn), which promotes neuronal death. We previously showed that treatment with miR-7 mimic prevents α-Syn induction and protects brain after stroke in rodents irrespective of age and sex. To further decipher the role of miR-7, we currently studied infarction and motor function in miR-7 double knockout mice (lack both miR-7a and miR-7b) subjected to focal ischemia. Adult miR-7-/- mice showed similar motor and cognitive functions to miR-7+/+ mice. However, when subjected to even a mild focal ischemia, the miR-7-/- mice showed exacerbated brain damage and worsened motor function compared with the miR-7+/+ mice. Replenishing miR-7 in miR-7-/- mice (IV injection of miR-7 mimic) restored miR-7 mediated neuroprotection and motor recovery, potentially by preventing α-Syn protein induction. Thus, we show that miR-7 is an essential miRNA in the brain that prevents α-Syn translation and the ensuing brain damage after stroke.

MMP-12 knockdown prevents secondary brain damage after ischemic stroke in mice.

We previously reported that increased expression of matrix metalloproteinase-12 (MMP-12) mediates blood-brain barrier disruption via tight junction protein degradation after focal cerebral ischemia in rats. Currently, we evaluated whether MMP-12 knockdown protects the post-stroke mouse brain and promotes better functional recovery. Adult male mice were injected with negative siRNA or MMP-12 siRNA (intravenous) at 5 min of reperfusion following 1 h transient middle cerebral artery occlusion. MMP-12 knockdown significantly reduced the post-ischemic infarct volume and improved motor and cognitive functional recovery. Mechanistically, MMP-12 knockdown ameliorated degradation of tight junction proteins zonula occludens-1, claudin-5, and occludin after focal ischemia. MMP-12 knockdown also decreased the expression of inflammatory mediators, including monocyte chemoattractant protein-1, tumor necrosis factor-α, and interleukin-6, and the expression of apoptosis marker cleaved caspase-3 after ischemia. Overall, the present study indicates that MMP-12 promotes secondary brain damage after stroke and hence is a promising stroke therapeutic target.

Epigenetic mechanisms and potential therapeutic targets in stroke.

Accumulating evidence indicates a central role for epigenetic modifications in the progression of stroke pathology. These epigenetic mechanisms are involved in complex and dynamic processes that modulate post-stroke gene expression, cellular injury response, motor function, and cognitive ability. Despite decades of research, stroke continues to be classified as a leading cause of death and disability worldwide with limited clinical interventions. Thus, technological advances in the field of epigenetics may provide innovative targets to develop new stroke therapies. This review presents the evidence on the impact of epigenomic readers, writers, and erasers in both ischemic and hemorrhagic stroke pathophysiology. We specifically explore the role of DNA methylation, DNA hydroxymethylation, histone modifications, and epigenomic regulation by long non-coding RNAs in modulating gene expression and functional outcome after stroke. Furthermore, we highlight promising pharmacological approaches and biomarkers in relation to epigenetics for translational therapeutic applications.

An antioxidant and anti-ER stress combo therapy decreases inflammation, secondary brain damage and promotes neurological recovery following traumatic brain injury in mice.

The complex pathophysiology of post-traumatic brain damage might need a polypharmacological strategy with a combination of drugs that target multiple, synergistic mechanisms. We currently tested a combination of apocynin (curtails formation of reactive oxygen species; ROS), tert-butylhydroquinone (promotes disposal of ROS), and salubrinal (prevents endoplasmic reticulum stress) following a moderate traumatic brain injury (TBI) induced by controlled cortical impact in adult mice. Adult mice of both sexes treated with the above tri-combo showed alleviated motor and cognitive deficits, attenuated secondary lesion volume, and decreased oxidative DNA damage. Concomitantly, tri-combo treatment regulated post-TBI inflammatory response by decreasing the infiltration of T cells and neutrophils and activation of microglia in both sexes. Interestingly, sexual dimorphism was seen in the case of TBI-induced microgliosis and infiltration of macrophages in the tri-combo treated mice. Moreover, the tri-combo treatment prevented TBI-induced white matter volume loss in both sexes. The beneficial effects of tri-combo treatment were long-lasting and were also seen in aged mice. Thus, the present study supports the tri-combo treatment to curtail oxidative stress and endoplasmic reticulum stress concomitantly as a therapeutic strategy to improve TBI outcomes.SIGNIFICANCE STATEMENTOf the several mechanisms that contribute to TBI pathophysiology, oxidative stress, endoplasmic reticulum (ER) stress, and inflammation play a major role. The present study shows the therapeutic potential of a combination of apocynin, tert-butylhydroquinone, and salubrinal to prevent oxidative stress and ER stress and the interrelated inflammatory response in mice subjected to TBI. The beneficial effects of the tri-combo include alleviation of TBI-induced motor and cognitive deficits and lesion volume. The neuroprotective effects of the tri-combo are also linked to its ability to prevent TBI-induced white matter damage. Importantly, neuroprotection by the tri-combo treatment was observed to be not dependent on sex or age. Our data demonstrate that a polypharmacological strategy is efficacious after TBI.

Gut virome dysbiosis following focal cerebral ischemia in mice.

Stroke leads to gut bacterial dysbiosis that impacts the post-stroke outcome. The gut microbiome also contains a high abundance of viruses which might play a crucial role in disease progression and recovery by modulating the metabolism of both host and host's gut bacteria. We presently analyzed the virome composition (viruses and phages) by shotgun metagenomics in the fecal samples obtained at 1 day of reperfusion following transient focal ischemia in adult mice. Viral genomes, viral auxiliary metabolic genes, and viral protein networks were compared between stroke and sham conditions (stroke vs sham, exclusive to sham and exclusive to stroke). Following focal ischemia, abundances of 2 viral taxa decreased, and 5 viral taxa increased compared with the sham. Furthermore, the abundance of Clostridia-like phages and Erysipelatoclostridiaceae-like phages were altered in the stroke compared with the sham cohorts. This is the first report to show that the gut virome responds acutely to stroke.

CXCL13 expressed on inflamed cerebral blood vessels recruit IL-21 producing TFH cells to damage neurons following stroke.

BACKGROUND: Ischemic stroke is a leading cause of mortality worldwide, largely due to the inflammatory response to brain ischemia during post-stroke reperfusion. Despite ongoing intensive research, there have not been any clinically approved drugs targeting the inflammatory component to stroke. Preclinical studies have identified T cells as pro-inflammatory mediators of ischemic brain damage, yet mechanisms that regulate the infiltration and phenotype of these cells are lacking. Further understanding of how T cells migrate to the ischemic brain and facilitate neuronal death during brain ischemia can reveal novel targets for post-stroke intervention. METHODS: To identify the population of T cells that produce IL-21 and contribute to stroke, we performed transient middle cerebral artery occlusion (tMCAO) in mice and performed flow cytometry on brain tissue. We also utilized immunohistochemistry in both mouse and human brain sections to identify cell types and inflammatory mediators related to stroke-induced IL-21 signaling. To mechanistically demonstrate our findings, we employed pharmacological inhibitor anti-CXCL13 and performed histological analyses to evaluate its effects on brain infarct damage. Finally, to evaluate cellular mechanisms of stroke, we exposed mouse primary neurons to oxygen glucose deprivation (OGD) conditions with or without IL-21 and measured cell viability, caspase activity and JAK/STAT signaling. RESULTS: Flow cytometry on brains from mice following tMCAO identified a novel population of cells IL-21 producing CXCR5+ CD4+ ICOS-1+ T follicular helper cells (TFH) in the ischemic brain early after injury. We observed augmented expression of CXCL13 on inflamed brain vascular cells and demonstrated that inhibition of CXCL13 protects mice from tMCAO by restricting the migration and influence of IL-21 producing TFH cells in the ischemic brain. We also illustrate that neurons express IL-21R in the peri-infarct regions of both mice and human stroke tissue in vivo. Lastly, we found that IL-21 acts on mouse primary ischemic neurons to activate the JAK/STAT pathway and induce caspase 3/7-mediated apoptosis in vitro. CONCLUSION: These findings identify a novel mechanism for how pro-inflammatory T cells are recruited to the ischemic brain to propagate stroke damage and provide a potential new therapeutic target for stroke.

Integrative epigenomic and transcriptomic analyses reveal metabolic switching by intermittent fasting in brain.

Intermittent fasting (IF) remains the most effective intervention to achieve robust anti-aging effects and attenuation of age-related diseases in various species. Epigenetic modifications mediate the biological effects of several environmental factors on gene expression; however, no information is available on the effects of IF on the epigenome. Here, we first found that IF for 3 months caused modulation of H3K9 trimethylation (H3K9me3) in the cerebellum, which in turn orchestrated a plethora of transcriptomic changes involved in robust metabolic switching processes commonly observed during IF. Second, a portion of both the epigenomic and transcriptomic modulations induced by IF was remarkably preserved for at least 3 months post-IF refeeding, indicating that memory of IF-induced epigenetic changes was maintained. Notably, though, we found that termination of IF resulted in a loss of H3K9me3 regulation of the transcriptome. Collectively, our study characterizes the novel effects of IF on the epigenetic-transcriptomic axis, which controls myriad metabolic processes. The comprehensive analyses undertaken in this study reveal a molecular framework for understanding how IF impacts the metabolo-epigenetic axis of the brain and will serve as a valuable resource for future research.

High-Dose Vitamin C Prevents Secondary Brain Damage After Stroke via Epigenetic Reprogramming of Neuroprotective Genes.

Vitamin C has recently been identified as an epigenetic regulator by activating ten-eleven translocases (TETs), enzymes involved in generating DNA hydroxymethylcytosine (5hmC). Currently, we investigated whether high-dose vitamin C promotes neuroprotection through epigenetic modulation of 5hmC, if there are sex-specific differences in outcome, and the therapeutic potential of vitamin C in stroke-related comorbidities in adult mice. Post-stroke treatment with ascorbate (reduced form), but not dehydroascorbate (oxidized form), increased TET3 activity and 5hmC levels and reduced infarct following focal ischemia. Hydroxymethylation DNA immunoprecipitation sequencing showed that ascorbate increased 5hmC across the genome and specifically in promoters of several stroke pathophysiology-related genes, particularly anti-inflammatory genes. Ascorbate also decreased markers of oxidative stress, mitochondrial fragmentation, and apoptosis in cortical peri-infarct neurons and promoted motor and cognitive functional recovery in both sexes via TET3. Furthermore, post-stroke ascorbate treatment reduced infarct volume and improved motor function recovery in aged, hypertensive and diabetic male and female mice. Delayed ascorbate treatment at 6 h of reperfusion was still effective at reducing infarct volume and motor impairments in adult mice. Collectively, this study shows that post-stroke treatment with high-dose ascorbate protects the brain through epigenetic reprogramming and may function as a robust therapeutic against stroke injury.