Niaspan increases axonal remodeling after stroke in type 1 diabetes rats

Changes in Type 1 Diabetes-Associated Gut Microbiota Aggravate Brain Ischemia Injury by Affecting Microglial Polarization Via the Butyrate-MyD88 Pathway in Mice

People with type 1 diabetes (T1D) have a significantly elevated risk of stroke, but the mechanism through which T1D worsens ischemic stroke remains unclear. This study was aimed at investigating the roles of T1D-associated changes in the gut microbiota in aggravating ischemic stroke and the underlying mechanism. Fecal 16SrRNA sequencing indicated that T1D mice and mice with transplantation of T1D mouse gut microbiota had lower relative abundance of butyric acid producers, f_Erysipelotrichaceae and g_Allobaculum, and lower content of butyric acid in feces. After middle cerebral artery occlusion (MCAO), these mice had poorer neurological outcomes and more severe inflammation, but higher expression of myeloid differentiation factor 88 (MyD88) in the ischemic penumbra; moreover, the microglia were inclined to polarize toward the pro-inflammatory type. Administration of butyrate to T1D mice in the drinking water alleviated the neurological damage after MCAO. Butyrate influenced the response and polarization of BV2 and decreased the production of inflammatory cytokines via MyD88 after oxygen-glucose deprivation/reoxygenation. Knocking down MyD88 in the brain alleviated neurological outcomes and decreased the concentrations of inflammatory cytokines in the brain after stroke in mice with transplantation of T1D mouse gut microbiota. Poor neurological outcomes and aggravated inflammatory responses of T1D mice after ischemic stroke may be partly due to differences in microglial polarization mediated by the gut microbiota-butyrate-MyD88 pathway. These findings provide new ideas and potential intervention targets for alleviating neurological damage after ischemic stroke in T1D.

Enriched environment treatment promotes neurofunctional recovery by regulating the ALK5/Smad2/3/Gadd45β signaling pathway in rats with cerebral ischemia /reperfusion injury

It has been demonstrated that an enriched environment (EE) treatment can alter neuroplasticity in neurodegenerative diseases. However, the role of EE treatment in ischemic stroke remains unclear. Previous findings have revealed that EE treatment can promote cerebral activin-receptor-like-kinase-5 (ALK5) expression after cerebral ischemia/reperfusion (I/R) injury. ALK5 has been identified as a potential mediator of neuroplasticity through its modulation of Smad2/3 and Gadd45β. Therefore, the aim of this study was to investigate whether EE treatment could promote neurofunctional recovery by regulating the ALK5/Smad2/3/Gadd45β pathway. The study utilized the rat model of middle cerebral artery occlusion/reperfusion (MCAO/R). The ALK5/Smad2/3/Gadd45β signaling pathway changes were evaluated using western blotting (WB). Brain injury was assessed by infarct volume and neurobehavioral scores. The effect of EE treatment on neurogenesis was evaluated using Doublecortin (DCX) and Nestin, axonal plasticity with biotinylated dextran amine (BDA) nerve tracing, and dendritic plasticity was assessed using Golgi-Cox staining. EE treatment has been demonstrated to modulate the Smad2/3/Gadd45β pathway by regulating the expression of ALK5. The protective effects of EE treatment on brain infarct volume, neurological function, newborn neurons, dendritic and axonal plasticity following cerebral I/R injury were counteracted by ALK5 silencing. EE treatment can enhance neurofunctional recovery after cerebral I/R injury, which is achieved by regulating the ALK5/Smad2/3/Gadd45β signaling pathway to promote neuroplasticity.

The role of high mobility group box-1 on the development of diabetes complications: A plausible pharmacological target

BACKGROUND

Diabetes mellitus has emerged as a pressing global concern, with a notable increase in recent years. Despite advancements in treatment, existing medications struggle to halt the progression of diabetes and its associated complications. Increasing evidence underscores inflammation as a significant driver in the onset of diabetes mellitus. Therefore, perspectives on new therapies must consider shifting focus from metabolic stress to inflammation. High mobility group box (HMGB-1), a nuclear protein regulating gene expression, gained attention as an endogenous danger signal capable of sparking inflammatory responses upon release into the extracellular environment in the late 1990s.

PURPOSE

Given the parallels between inflammatory responses and type 2 diabetes (T2D) development, this review paper explores HMGB-1's potential involvement in onset and progression of diabetes complications. Specifically, we will review and update the understanding of HMGB-1 and its inflammatory pathways in insulin resistance, diabetic nephropathy, diabetic neuropathy, and diabetic retinopathy.

CONCLUSIONS

HMGB-1 and its receptors i.e. receptor for advanced glycation end-products (RAGE) and toll-like receptors (TLRs) present promising targets for antidiabetic interventions. Ongoing and future projects in this realm hold promise for innovative approaches targeting HMGB-1-mediated inflammation to ameliorate diabetes and its complications.

STZ-induced diabetes exacerbates neurons ferroptosis after ischemic stroke by upregulating LCN2 in neutrophils

Diabetic is a major contributor to the unfavorable prognosis of ischemic stroke. However, intensive hypoglycemic strategies do not improve stroke outcomes, implying that diabetes may affect stroke outcomes through other ways. Ferroptosis is a novel programmed cell death pathway associated with the development of diabetes and ischemic stroke. This study aimed to investigate the effect of streptozotocin (STZ)-induced diabetes on ferroptosis after stroke from the immune cell perspective, and to provide a theoretical foundation for the clinical management of ischemic stroke in patients with diabetes. The results revealed that STZ-induced diabetes not only facilitates the infiltration of neutrophils into the brain after stroke, but also upregulates the expression of lipocalin 2 (LCN2) in neutrophils. LCN2 promotes lipid peroxide accumulation by increasing intracellular ferrous ions, which intensify ferroptosis in major brain cell populations, especially neurons. Our findings suggest that STZ-induced diabetes aggravates ischemic stroke partially by mediating ferroptosis through neutrophil-derived LCN2. These data contribute to improved understanding of post-stroke immune regulation in diabetes, and offer a potentially novel therapeutic target for the management of acute-stage ischemic stroke complicated with diabetes.

Melatonin at repeated doses alleviates hyperglycemia-exacerbated cerebral ischemia-reperfusion injury at 72 h via anti-inflammation and anti-apoptosis

Objective

We aimed to investigate how hyperglycemia would exacerbate cerebral ischemia-reperfusion injury (CIRI) in a rat model of type 1 diabetes mellitus (T1DM) and explore the beneficial effects of multiple doses of melatonin in T1DM induced CIRI.

Method

The T1DM rat model was induced with streptozocin, and melatonin (10 mg/kg) was injected at 0.5 h before ischemia as well as at 24 and 48 h after reperfusion.

Results

When compared to normoglycemic (NG) rats, T1DM rats had hyperglycemia with weight loss before CIRI. Despite comparable degrees of ischemia and initial reperfusion, T1DM rats tended to have greater weight loss and had worse neurological deficits and larger infarct volume than NG rats up to 72 h after CIRI. Persistent activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway but not of apoptosis or calpains was a crucial factor in T1DM-mediated exacerbation of CIRI at 72 h. Despite lacking effects on baseline hyperglycemia, ischemia and initial reperfusion, melatonin at multiple doses lessened post-CIRI weight loss, neurological deficits and infarct volume in T1DM rats at 72 h. when compared to vehicle-treated T1DM rats with CIRI. Beneficial effects of melatonin treatment included decreased activation of NF-κB pathway, apoptosis and calpains, leading to reduced expression of inducible nitric oxide synthase and enhanced neuronal density.

Conclusion

Melatonin at multiple doses can alleviate T1DM-mediated exacerbation of CIRI at 72 h through anti-inflammation and anti-apoptosis.

Melatonin mitigates type 1 diabetes-aggravated cerebral ischemia-reperfusion injury through anti-inflammatory and anti-apoptotic effects

INTRODUCTION

Cerebral ischemia and diabetes mellitus (DM) are common diseases that often coexist and interact with each other. DM doubles the risk of ischemic stroke, and cerebral ischemia causes stress-induced hyperglycemia. Most experimental stroke studies used healthy animals. Melatonin is neuroprotective against cerebral ischemia-reperfusion injury (CIRI) in non-DM, normoglycemic animals through anti-oxidant effect, anti-inflammation, and anti-apoptosis. Previous studies have also reported a negative correlation between hyperglycemia and urinary melatonin metabolite.

OBJECTIVES

The present study investigated the effects of type 1 DM (T1DM) on CIRI in rats and the role of melatonin against CIRI in T1DM animals.

RESULTS

Our results revealed that T1DM aggravated CIRI, leading to greater weight loss, increased infarct volume, and worse neurological deficit. T1DM aggravated the post-CIRI activation of nuclear factor kappa B (NF-κB) pathway and increase in pro-apoptotic markers. A single intraperitoneal injection of melatonin at 10 mg/kg given 30 min before ischemia onset attenuated CIRI in T1DM rats, resulting in less weight loss, decreased infarct volume, and milder neurological deficit when compared with the vehicle group. Melatonin treatment achieved anti-inflammatory and anti-apoptotic effects with reduced NF-κB pathway activation, reduced mitochondrial cytochrome C release, decreased calpain-mediated spectrin breakdown product (SBDP), and decreased caspase-3-mediated SBDP. The treatment also led to fewer iNOS+ cells, milder CD-68+ macrophage/microglia infiltration, decreased TUNEL+ apoptotic cells, and better neuronal survival.

CONCLUSIONS

T1DM aggravates CIRI. Melatonin treatment is neuroprotective against CIRI in T1DM rats via anti-inflammatory and anti-apoptotic effects.

Exacerbated VEGF up-regulation accompanies diabetes-aggravated hemorrhage in mice after experimental cerebral ischemia and delayed reperfusion

Reperfusion therapy is the preferred treatment for ischemic stroke, but is hindered by its short treatment window, especially in patients with diabetes whose reperfusion after prolonged ischemia is often accompanied by exacerbated hemorrhage. The mechanisms underlying exacerbated hemorrhage are not fully understood. This study aimed to identify this mechanism by inducing prolonged 2-hour transient intraluminal middle cerebral artery occlusion in diabetic Ins2^Akita/+ mice to mimic patients with diabetes undergoing delayed mechanical thrombectomy. The results showed that at as early as 2 hours after reperfusion, Ins2^Akita/+ mice exhibited rapid development of neurological deficits, increased infarct and hemorrhagic transformation, together with exacerbated down-regulation of tight-junction protein ZO-1 and up-regulation of blood-brain barrier-disrupting matrix metallopeptidase 2 and matrix metallopeptidase 9 when compared with normoglycemic Ins2^+/+ mice. This indicated that diabetes led to the rapid compromise of vessel integrity immediately after reperfusion, and consequently earlier death and further aggravation of hemorrhagic transformation 22 hours after reperfusion. This observation was associated with earlier and stronger up-regulation of pro-angiogenic vascular endothelial growth factor (VEGF) and its downstream phospho-Erk1/2 at 2 hours after reperfusion, which was suggestive of premature angiogenesis induced by early VEGF up-regulation, resulting in rapid vessel disintegration in diabetic stroke. Endoplasmic reticulum stress-related pro-apoptotic C/EBP homologous protein was overexpressed in challenged Ins2^Akita/+ mice, which suggests that the exacerbated VEGF up-regulation may be caused by overwhelming endoplasmic reticulum stress under diabetic conditions. In conclusion, the results mimicked complications in patients with diabetes undergoing delayed mechanical thrombectomy, and diabetes-induced accelerated VEGF up-regulation is likely to underlie exacerbated hemorrhagic transformation. Thus, suppression of the VEGF pathway could be a potential approach to allow reperfusion therapy in patients with diabetic stroke beyond the current treatment window. Experiments were approved by the Committee on the Use of Live Animals in Teaching and Research of the University of Hong Kong [CULATR 3834-15 (approval date January 5, 2016); 3977-16 (approval date April 13, 2016); and 4666-18 (approval date March 29, 2018)].

Effect of Diabetes on Post-stroke Recovery: A Systematic Narrative Review

Background: Patients with stroke often have comorbid diabetes. Considering its detrimental effects on brain function, diabetes may increase the risk of poor recovery.

Methods: The aim of this review was to investigate the effect of diabetes on post-stroke recovery by a systematic review. Several specific aspects of post-stroke recovery, including activities of daily living (ADL), motor, cognitive, and quality of life (QOL) recovery, were examined. We searched the PubMed, SCOPUS, Embase, and Cochrane Library databases for relevant studies on the effect of diabetes on post-stroke recovery, published until May 26, 2021. A total of 52,051 potentially relevant articles were identified. After reading the titles and abstracts and assessing their eligibility based on full-text articles, 34 publications were included in this review.

Results: Of 29 studies that assessed ADL recovery after stroke, 22 studies suggested that diabetes had a negative effect on recovery of ADL after stroke. Regarding motor recovery, only one out of four studies showed that diabetes had some effect on motor recovery after stroke. Of the two studies on cognitive recovery, one reported that diabetes was an independent predictor of poor cognitive recovery after stroke. Three studies on QOL reported that a poor QOL after stroke was associated with the presence of diabetes.

Conclusions: The current review suggests that the post-stroke recovery of ADL seems to be poorer in patients with diabetes than patients without diabetes. Further, there are insufficient data to conclude the effect of diabetes on motor and cognitive recovery, but it may have some influence on the quality of life after stroke.

Systematic Review Registration: doi: 10.37766/inplasy2021.11.0032, identifier: INPLASY2021110032.

Human amniotic fluid stem cells can improve cerebral vascular remodelling and neurological function after focal cerebral ischaemia in diabetic rats

Diabetes causes vascular injury and carries a high risk of ischaemic stroke. Human amniotic fluid stem cells (hAFSCs) can enhance cerebral vascular remodelling and have the potential to improve neurological function after stroke in diabetic rats. Five groups of female rats were examined: (1) normal control, (2) type 1 diabetic (T1DM) rats induced by streptozotocin injection (DM), (3) non‐DM rats receiving 60‐minute middle cerebral artery occlusion (MCAO), (4) T1DM rats receiving 60‐minute MCAO (DM + MCAO) and (5) T1DM rats receiving 60‐minute MCAO and injection with 5 × 10⁶ hAFSCs at 3 h after MCAO (DM + MCAO + hAFSCs). Neurological function was examined before, and at 1, 7, 14, 21 and 28 days, and cerebral infarction volume and haemorrhage, cerebral vascular density, angiogenesis and inflammatory were examined at 7 and 28 days after MCAO. hAFSCs treatment caused a significant improvement of neurological dysfunction, infarction volume, blood‐brain barrier leakage, cerebral arterial density, vascular density and angiogenesis and a reduction of brain haemorrhage and inflammation compared with non‐treatment. Our results showed that the effect of hAFSCs treatment against focal cerebral ischaemia may act through the recovery of vascular remodelling and angiogenesis and the reduction of inflammation in ischaemic brain.

Clarifying the effects of diabetes on the cerebral circulation: Implications for stroke recovery and beyond

Given the sheer increased number of victims per year and the availability of only one effective treatment, acute ischemic stroke (AIS) remains to be one of the most under-treated serious diseases. Diabetes not only increases the incidence of ischemic stroke, but amplifies the ischemic damage, upon which if patients with diabetes suffer from stroke, he/she will confront increased risks of long-term functional deficits. The grim reality makes it a pressing need to intensify efforts at the basic science level to understand how diabetes impairs stroke recovery. This review retrospects the clinical and experimental studies in order to elucidate the detrimental effect of diabetes on cerebrovascular circulation including the major arteries/arterioles, collateral circulation, and neovascularization to shed light on further exploration of novel strategies for cerebral circulation protection before and after AIS in patients with diabetes.

Spontaneous Neuronal Plasticity in the Contralateral Motor Cortex and Corticospinal Tract after Focal Cortical Infarction in Hypertensive Rats

OBJECTIVES

In this study, we investigated the spontaneous neural plasticity on the contralateral side in hypertensive rats, including the expression of nerve growth factors (synaptophysin [SYN] and growth-associated protein 43 [GAP-43]), and the association between nerve fiber sprouting and redistribution, and the recovery of motor functions following sensorimotor cortical infarction.

METHODS

Initially, Sprague-Dawley rats were induced with renal hypertension by the bilateral renal arteries clips method. Further, they were induced with cerebral ischemia by the middle cerebral artery electrocoagulation method; 70 male rats completed the study. We compared the changes in the corticospinal tract (CST) and the expressions of SYN and GAP-43 on the contralateral side in rats with cerebral infarction using immunohistochemical staining, western blot, and biotinylated dextran amine (BDA) tracing analyses. The recovery of motor function in rats after cortical infarction was evaluated by the foot-fault and beam-walk tests.

RESULTS

The motor behavior tests revealed that the motor function of rats could recover to various degrees after focal cortical infarction. Compared with the sham-operated group, the SYN and GAP-43 levels increased in the motor cortex of the opposite hemisphere within 28 days after middle cerebral artery occlusion (MCAO). The increase in SYN and GAP-43 expressions presented differently in layers Ⅱ, Ⅲ, and Ⅴ. The amount of BDA-positive fibers also increased significantly in the denervated cervical spinal gray matter on day 56 post-MCAO.

CONCLUSIONS

The increases in SYN and GAP-43 on the contralateral side of the motor cortex could promote CST sprouting and rewiring in the spinal cord gray matter and also spontaneous motor function recovery after cortical infarction.

Diabetes Mellitus-Related Dysfunction of the Motor System

Although motor deficits in humans with diabetic neuropathy have been extensively researched, its effect on the motor system is thought to be lesser than that on the sensory system. Therefore, motor deficits are considered to be only due to sensory and muscle impairment. However, recent clinical and experimental studies have revealed that the brain and spinal cord, which are involved in the motor control of voluntary movement, are also affected by diabetes. This review focuses on the most important systems for voluntary motor control, mainly the cortico-muscular pathways, such as corticospinal tract and spinal motor neuron abnormalities. Specifically, axonal damage characterized by the proximodistal phenotype occurs in the corticospinal tract and motor neurons with long axons, and the transmission of motor commands from the brain to the muscles is impaired. These findings provide a new perspective to explain motor deficits in humans with diabetes. Finally, pharmacological and non-pharmacological treatment strategies for these disorders are presented.

Nutritional and medical food therapies for diabetic retinopathy

Diabetic retinopathy (DR) is a form of microangiopathy. Reducing oxidative stress in the mitochondria and cell membranes decreases ischemic injury and end-organ damage to the retina. New approaches are needed, which reduce the risk and improve the outcomes of DR while complementing current therapeutic approaches. Homocysteine (Hcy) elevation and oxidative stress are potential therapeutic targets in DR. Common genetic polymorphisms such as those of methylenetetrahydrofolate reductase (MTHFR), increase Hcy and DR risk and severity. Patients with DR have high incidences of deficiencies of crucial vitamins, minerals, and related compounds, which also lead to elevation of Hcy and oxidative stress. Addressing the effects of the MTHFR polymorphism and addressing comorbid deficiencies and insufficiencies reduce the impact and severity of the disease. This approach provides safe and simple strategies that support conventional care and improve outcomes. Suboptimal vitamin co-factor availability also impairs the release of neurotrophic and neuroprotective growth factors. Collectively, this accounts for variability in presentation and response of DR to conventional therapy. Fortunately, there are straightforward recommendations for addressing these issues and supporting traditional treatment plans. We have reviewed the literature for nutritional interventions that support conventional therapies to reduce disease risk and severity. Optimal combinations of vitamins B1, B2, B6, L-methylfolate, methylcobalamin (B12), C, D, natural vitamin E complex, lutein, zeaxanthin, alpha-lipoic acid, and n-acetylcysteine are identified for protecting the retina and choroid. Certain medical foods have been successfully used as therapy for retinopathy. Recommendations based on this review and our clinical experience are developed for clinicians to use to support conventional therapy for DR. DR from both type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) have similar retinal findings and responses to nutritional therapies.

High Mobility Group Box-1 and Diabetes Mellitus Complications: State of the Art and Future Perspectives

Diabetes mellitus (DM) is an endemic disease, with growing health and social costs. The complications of diabetes can affect potentially all parts of the human body, from the heart to the kidneys, peripheral and central nervous system, and the vascular bed. Although many mechanisms have been studied, not all players responsible for these complications have been defined yet. High Mobility Group Box-1 (HMGB1) is a non-histone nuclear protein that has been implicated in many pathological processes, from sepsis to ischemia. The purpose of this review is to take stock of all the most recent data available on the role of HMGB1 in the complications of DM.

Inhibition of microRNA-711 limits angiopoietin-1 and Akt changes, tissue damage, and motor dysfunction after contusive spinal cord injury in mice

Spinal cord injury (SCI) causes neuronal cell death and vascular damage, which contribute to neurological dysfunction. Given that many biochemical changes contribute to such secondary injury, treatment approaches have increasingly focused on combined therapies or use of multi-functional drugs. MicroRNAs (miRs) are small (20-23 nucleotide), non-protein-coding RNAs and can negatively regulate target gene expression at the post-transcriptional level. As individual miRs can potentially modulate expression of multiple relevant proteins after injury, they are attractive candidates as upstream regulators of the secondary SCI progression. In the present study we examined the role of miR-711 modulation after SCI. Levels of miR-711 were increased in injured spinal cord early after SCI, accompanied by rapid downregulation of its target angiopoietin-1 (Ang-1), an endothelial growth factor. Changes of miR-711 were also associated with downregulation of the pro-survival protein Akt (protein kinase B), another target of miR-711, with sequential activation of glycogen synthase kinase 3 and the pro-apoptotic BH3-only molecule PUMA. Central administration of a miR-711 hairpin inhibitor after SCI limited decreases of Ang-1/Akt expression and attenuated apoptotic pathways. Such treatment also reduced neuronal/axonal damage, protected microvasculature and improved motor dysfunction following SCI. In vitro, miR-711 levels were rapidly elevated by neuronal insults, but not by activated microglia and astrocytes. Together, our data suggest that post-traumatic miR-711 elevation contributes to neuronal cell death after SCI, in part by inhibiting Ang-1 and Akt pathways, and may serve as a novel therapeutic target.

Effect of pharmacological doses of niacin on testicular structure and function in normal and diabetic rats

Male diabetic patients may experience adverse changes in testicular functions or structure. Niacin has antidyslipidemic properties in diabetic patients. We aimed to clarify the effect of pharmacological doses of niacin on testicular structure and function of normal and diabetic rats. Sixty adult male rats were treated as follows. Healthy control (HC); diabetic control (DC); NL and NH groups: normal rats that received niacin at 800 and 4,000 mg/kg of diet; DL and DH groups: diabetic rats that received niacin at 800 and 4,000 mg/kg diet for 50 days. In normal rats, obvious increase in serum testosterone especially in NL group associated with improved antioxidant status of testicular tissue was observed. In diabetic rats, niacin resulted in higher testicular weight/body weight and improved some histological parameters without affecting blood glucose, testosterone and sperm count. Testicular MDA content decreased. In conclusion, niacin especially at 800 mg/kg diet improves serum testosterone levels and antioxidant status of testes in normal rats. In diabetic rats, despite positive changes in histological features and antioxidant status of testes reproductive outcome including sperm count or testosterone levels were not improved. This study set the scene for further investigations on the effect of niacin on male reproductive system.

Advances in stroke pharmacology

Stroke occurs when a cerebral blood vessel is blocked or ruptured, and it is the major cause of death and adult disability worldwide. Various pharmacological agents have been developed for the treatment of stroke either through interrupting the molecular pathways leading to neuronal death or enhancing neuronal survival and regeneration. Except for rtPA, few of these agents have succeeded in clinical trials. Recently, with the understanding of the pathophysiological process of stroke, there is a resurrection of research on developing neuroprotective agents for stroke treatment, and novel molecular targets for neuroprotection and neurorestoration have been discovered to predict or offer clinical benefits. Here we review the latest major progress of pharmacological studies in stroke, especially in ischemic stroke; summarize emerging potential therapeutic mechanisms; and highlight recent clinical trials. The aim of this review is to provide a panorama of pharmacological interventions for stroke and bridge basic and translational research to guide the clinical management of stroke therapy.

Coenzyme Q10 and niacin mitigate streptozotocin- induced diabetic encephalopathy in a rat model

Diabetic encephalopathy is an important complication of diabetes characterized by cognitive impairment, neurochemical and structural abnormalities. This study aimed to investigate the effect of coenzyme Q10 (CoQ10) and niacin as well as their combination in the treatment of encephalopathy associated with streptozotocin (STZ)- induced diabetes in rats. Glibenclamide (reference diabetic drug) and donepezil hydrochloride (acetylcholinesterase inhibitor) were also evaluated. Diabetes was induced by a single intraperitoneal injection of STZ (60 mg/kg). One month after STZ injection, diabetic rats were treated with the aforementioned drugs for two weeks. The evaluation was done through measuring glucose level, total antioxidant capacity (TAC), interleukin 6 (IL6), DNA degradation as well as serotonin and noradrenaline as neurotransmitters. The present data illustrated that combining CoQ10 and niacin exhibiting the most potent effect in improving the measured parameters and ameliorating some of diabetes complications.

Cell-based and pharmacological neurorestorative therapies for ischemic stroke

Ischemic stroke remains one of most common causes of death and disability worldwide. Stroke triggers a cascade of events leading to rapid neuronal damage and death. Neuroprotective agents that showed promise in preclinical experiments have failed to translate to the clinic. Even after decades of research, tPA remains the only FDA approved drug for stroke treatment. However, tPA is effective when administered 3-4.5 h after stroke onset and the vast majority of stroke patients do not receive tPA therapy. Therefore, there is a pressing need for novel therapies for ischemic stroke. Since stroke induces rapid cell damage and death, neuroprotective strategies that aim to salvage or replace injured brain tissue are challenged by treatment time frames. To overcome the barriers of neuroprotective therapies, there is an increasing focus on neurorestorative therapies for stroke. In this review article, we provide an update on neurorestorative treatments for stroke using cell therapy such as bone marrow derived mesenchymal stromal cells (BMSCs), human umbilical cord blood cells (HUCBCs) and select pharmacological approaches including Minocycline and Candesartan that have been employed in clinical trials. This review article discusses the present understanding of mechanisms of neurorestorative therapies and summarizes ongoing clinical trials. This article is part of the Special Issue entitled 'Cerebral Ischemia'.

The Effect of Diabetes on Cortical Function in Stroke: Implications for Poststroke Plasticity

Diabetes may impair the capacity for neuroplasticity such that patients experience a slower and poorer recovery after stroke. The current study investigated changes in cortical function in stroke patients with diabetes to determine how this comorbidity may affect poststroke cortical plasticity and thereby functional recovery. From a cohort of 57 participants, threshold-tracking transcranial magnetic stimulation was used to assess cortical function over the ipsilateral and contralesional hemispheres in 7 patients with diabetes after an acute stroke compared with 12 stroke patients without diabetes. Cortical function was also assessed in 8 patients with diabetes without stroke and 30 normal control subjects. After acute stroke, short-interval intracortical inhibition (SICI) was reduced over both motor cortices in stroke patients without diabetes compared with normal control patients, while in stroke patients with diabetes, SICI was only reduced over the contralesional but not the ipsilesional cortex compared with control patients with diabetes. In addition, SICI was significantly reduced in the control patients with diabetes compared with normal control patients. These results have demonstrated the absence of ipsilesional cortical excitability change after diabetic strokes, suggesting impaired capacity for neuroplasticity over this hemisphere as a consequence of a "double-hit" phenomenon because of preexisting alterations in cortical function in nonstroke patients with diabetes. The reliance on reorganization over the contralesional cortex after stroke will likely exert influence on poststroke recovery in patients with diabetes.

Diabetes Worsens Functional Outcomes in Young Female Rats: Comparison of Stroke Models, Tissue Plasminogen Activator Effects, and Sexes

Diabetes worsens stroke outcome and increases the risk of hemorrhagic transformation (HT) after ischemic stroke, especially with tissue plasminogen activator (tPA) treatment. The widespread use of tPA is still limited by the fear of hemorrhagic transformation (HT), and underlying mechanisms are actively being pursued in preclinical studies. However, experimental models use a 10 times higher dose of tPA than the clinical dose (10 mg/kg) and mostly employ only male animals. In this translational study, we hypothesized that low-dose tPA will improve the functional recovery after the embolic stroke in both control and diabetic male and female animals. Diabetes was induced in age-matched male and female Wistar rats with high fat diet and low-dose streptozotocin (30 mg/kg, i.p.). Embolic stroke was induced with clot occlusion of the middle cerebral artery (MCA). The animals were treated with or without tPA (1 mg/kg, i.v.) at 90 min after surgery. An additional set of animals were subjected to 90 min MCAO with suture. Neurological deficits (composite score and adhesive removal test-ART), infarct size, edema ratio, and HT index were assessed 3 days after surgery. In the control groups, female rats had smaller infarcts and better functional outcomes. tPA decreased infarct size in both sexes with a greater effect in males. While there was no difference in HT between males and females without tPA, HT was less in the female + tPA group. In the diabetic groups, neuronal injury increased in females reaching that of the infarct sizes seen in male rats. tPA decreased infarct size in females but not males. HT was greater in female rats than in males and was not further increased with tPA. Diabetes worsened neurological deficits in both sexes. Male animals showed improved sensorimotor skills, especially with tPA treatment, but there was no improvement in females. These data suggest that diabetes amplifies neurovascular injury and neurological deficits in both sexes. Human dose tPA offers some degree of protection in male but not female rats. Given that control female animals experience less injury compared to male rats, the diabetes effect is more profound in females.

Lithium-induced neuroprotection in stroke involves increased miR-124 expression, reduced RE1-silencing transcription factor abundance and decreased protein deubiquitination by GSK3β inhibition-independent pathways

Lithium promotes acute poststroke neuronal survival, which includes mechanisms that are not limited to GSK3β inhibition. However, whether lithium induces long-term neuroprotection and enhanced brain remodeling is unclear. Therefore, mice were exposed to transient middle cerebral artery occlusion and lithium (1 mg/kg bolus followed by 2 mg/kg/day over up to 7 days) was intraperitoneally administered starting 0-9 h after reperfusion onset. Delivery of lithium no later than 6 h reduced infarct volume on day 2 and decreased brain edema, leukocyte infiltration, and microglial activation, as shown by histochemistry and flow cytometry. Lithium-induced neuroprotection persisted throughout the observation period of 56 days and was associated with enhanced neurological recovery. Poststroke angioneurogenesis and axonal plasticity were also enhanced by lithium. On the molecular level, lithium increased miR-124 expression, reduced RE1-silencing transcription factor abundance, and decreased protein deubiquitination in cultivated cortical neurons exposed to oxygen-glucose deprivation and in brains of mice exposed to cerebral ischemia. Notably, this effect was not mimicked by pharmacological GSK3β inhibition. This study for the first time provides efficacy data for lithium in the postacute ischemic phase, reporting a novel mechanism of action, i.e. increased miR-124 expression facilitating REST degradation by which lithium promotes postischemic neuroplasticity and angiogenesis.

Niacin-mediated Tace activation ameliorates CMT neuropathies with focal hypermyelination

Charcot–Marie–Tooth (CMT) neuropathies are highly heterogeneous disorders caused by mutations in more than 70 genes, with no available treatment. Thus, it is difficult to envisage a single suitable treatment for all pathogenetic mechanisms. Axonal Neuregulin 1 (Nrg1) type III drives Schwann cell myelination and determines myelin thickness by ErbB2/B3‐PI3K–Akt signaling pathway activation. Nrg1 type III is inhibited by the α‐secretase Tace, which negatively regulates PNS myelination. We hypothesized that modulation of Nrg1 levels and/or secretase activity may constitute a unifying treatment strategy for CMT neuropathies with focal hypermyelination as it could restore normal levels of myelination. Here we show that in vivo delivery of Niaspan, a FDA‐approved drug known to enhance TACE activity, efficiently rescues myelination in the Mtmr2^−/− mouse, a model of CMT4B1 with myelin outfoldings, and in the Pmp22^+/− mouse, which reproduces HNPP (hereditary neuropathy with liability to pressure palsies) with tomacula. Importantly, we also found that Niaspan reduces hypermyelination of Vim (vimentin)^−/− mice, characterized by increased Nrg1 type III and Akt activation, thus corroborating the hypothesis that Niaspan treatment downregulates Nrg1 type III signaling.

Illuminating the Effects of Stroke on the Diabetic Brain: Insights From Imaging Neural and Vascular Networks in Experimental Animal Models

Type 1 diabetes is known to cause circulatory problems in the eyes, heart, and limbs, and the brain is no exception. Because of the insidious effects of diabetes on brain circulation, patients with diabetes are two to four times more likely to have an ischemic stroke and are less likely to regain functions that are lost. To provide a more mechanistic understanding of this clinically significant problem, imaging studies have focused on how stroke affects neural and vascular networks in experimental models of type 1 diabetes. The emerging picture is that diabetes leads to maladaptive changes in the cerebrovascular system that ultimately limit neuronal rewiring and recovery of functions after stroke. At the cellular and systems level, diabetes is associated with abnormal cerebral blood flow in surviving brain regions and greater disruption of the blood-brain barrier. The abnormal vascular responses to stroke can be partly attributed to aberrant vascular endothelial growth factor (VEGF) signaling because genetic or pharmacological inhibition of VEGF signaling can mitigate vascular dysfunction and improve stroke recovery in diabetic animals. These experimental studies offer new insights and strategies for optimizing stroke recovery in diabetic populations.

Bone marrow stromal cells inhibits HMGB1-mediated inflammation after stroke in type 2 diabetic rats

High-mobility group box 1 (HMGB1), a ligand of receptor for advanced glycation endproducts (RAGE), functions as a proinflammatory factor. It is mainly involved in inflammatory activation and contributes to the initiation and progression of stroke. By using a model of transient middle cerebral artery occlusion (MCAo) in type 2 diabetic rats, we investigated the changes of pro-inflammation mediators, blood-brain barrier (BBB) leakage and functional outcome after stroke. Type 2 diabetic rats did not show an increased lesion volume, but exhibited significantly increased expression of HMGB1 and RAGE, BBB leakage, as well as decreased functional outcome after stroke compared with control rats. Injection of bone marrow stromal cells (BMSCs) into type 2 diabetic rats significantly reduced the expression of HMGB1 and RAGE, attenuated BBB leakage, and improved functional outcome after stroke. BMSCs-treated type 2 diabetic rats inhibited inflammation and improved functional outcome after stroke. Furthermore, in vitro data support the hypothesis that BMSCs-induced reduction of HMGB1 and RAGE in T2DM-MCAo rats contributed to attenuated inflammatory response in the ischemic brain, which may lead to the beneficial effects of BMSCs treatment. Further investigation of BMSCs treatment in type 2 diabetic stroke is warranted.

Promoting recovery from ischemic stroke

Over recent decades, experimental and clinical stroke studies have identified a number of neurorestorative treatments that stimulate neural plasticity and promote functional recovery. In contrast to the acute stroke treatments thrombolysis and endovascular thrombectomy, neurorestorative treatments are still effective when initiated days after stroke onset, which makes them applicable to virtually all stroke patients. In this article, selected physical, pharmacological and cell-based neurorestorative therapies are discussed, with special emphasis on interventions that have already been transferred from the laboratory to the clinical setting. We explain molecular and structural processes that promote neural plasticity, discuss potential limitations of neurorestorative treatments, and offer a speculative viewpoint on how neurorestorative treatments will evolve.

Experimental animal models and inflammatory cellular changes in cerebral ischemic and hemorrhagic stroke

Stroke, including cerebral ischemia, intracerebral hemorrhage, and subarachnoid hemorrhage, is the leading cause of long-term disability and death worldwide. Animal models have greatly contributed to our understanding of the risk factors and the pathophysiology of stroke, as well as the development of therapeutic strategies for its treatment. Further development and investigation of experimental models, however, are needed to elucidate the pathogenesis of stroke and to enhance and expand novel therapeutic targets. In this article, we provide an overview of the characteristics of commonly-used animal models of stroke and focus on the inflammatory responses to cerebral stroke, which may provide insights into a framework for developing effective therapies for stroke in humans.

Neurorestorative Therapy of Stroke in Type 2 Diabetes Mellitus Rats Treated With Human Umbilical Cord Blood Cells

BACKGROUND AND PURPOSE

Diabetes mellitus is a high-risk factor for ischemic stroke. Diabetic stroke patients suffer worse outcomes, poor long-term recovery, risk of recurrent strokes, and extensive vascular damage. We investigated the neurorestorative effects and the underlying mechanisms of stroke treatment with human umbilical cord blood cells (HUCBCs) in type 2 diabetes mellitus (T2DM) rats.

METHODS

Adult male T2DM rats were subjected to 2 hours of middle cerebral artery occlusion (MCAo). Three days after MCAo, rats were treated via tail-vein injection with (1) PBS and (2) HUCBCs (5×10(6)), n=10 per group.

RESULTS

HUCBC stroke treatment initiated 3 days after MCAo in T2DM rats did not significantly decrease blood-brain barrier leakage (P=0.1) and lesion volume (P=0.078), but significantly improved long-term functional outcome and decreased brain hemorrhage (P<0.05) when compared with the PBS-treated T2DM MCAo control group. HUCBC treatment significantly promoted white matter remodeling as indicated by increased expression of Bielschowsky silver (axons marker), Luxol fast blue (myelin marker), SMI-31 (neurofilament), and Synaptophysin in the ischemic border zone. HUCBC promoted vascular remodeling and significantly increased arterial and vascular density. HUCBC treatment of stroke in T2DM rats significantly increased M2 macrophage polarization (increased M2 macrophage, CD163and CD 206; decreased M1 macrophage, ED1 and inducible nitric oxide synthase expression) in the ischemic brain compared with PBS-treated T2DM MCAo controls (P<0.05). HUCBC also significantly decreased proinflammatory factors, that is, matrix metalloproteinase 9, receptor for advanced glycation end products and toll-like receptor 4 expression in the ischemic brain.

CONCLUSIONS

HUCBC treatment initiated 3 days after stroke significantly increased white matter and vascular remodeling in the ischemic brain as well as decreased neuroinflammatory factor expression in the ischemic brain in T2DM rats and promoted M2 macrophage polarization. HUCBC reduction of neuroinflammation and increased vascular and white matter axonal remodeling may contribute to the HUCBC-induced beneficial effects in T2DM stroke rats.

Effects of acute versus post-acute systemic delivery of neural progenitor cells on neurological recovery and brain remodeling after focal cerebral ischemia in mice

Intravenous transplantation of neural progenitor cells (NPCs) induces functional recovery after stroke, albeit grafted cells are not integrated into residing neural networks. However, a systematic analysis of intravenous NPC delivery at acute and post-acute time points and their long-term consequences does not exist. Male C57BL6 mice were exposed to cerebral ischemia, and NPCs were intravenously grafted on day 0, on day 1 or on day 28. Animals were allowed to survive for up to 84 days. Mice and tissues were used for immunohistochemical analysis, flow cytometry, ELISA and behavioral tests. Density of grafted NPCs within the ischemic hemisphere was increased when cells were transplanted on day 28 as compared with transplantation on days 0 or 1. Likewise, transplantation on day 28 yielded enhanced neuronal differentiation rates of grafted cells. Post-ischemic brain injury, however, was only reduced when NPCs were grafted at acute time points. On the contrary, reduced post-ischemic functional deficits due to NPC delivery were independent of transplantation paradigms. NPC-induced neuroprotection after acute cell delivery was due to stabilization of the blood–brain barrier (BBB), reduction in microglial activation and modulation of both peripheral and central immune responses. On the other hand, post-acute NPC transplantation stimulated post-ischemic regeneration via enhanced angioneurogenesis and increased axonal plasticity. Acute NPC delivery yields long-term neuroprotection via enhanced BBB integrity and modulation of post-ischemic immune responses, whereas post-acute NPC delivery increases post-ischemic angioneurogenesis and axonal plasticity. Post-ischemic functional recovery, however, is independent of NPC delivery timing, which offers a broad therapeutic time window for stroke treatment.

HUCBCs increase angiopoietin 1 and induce neurorestorative effects after stroke in T1DM rats

BACKGROUND AND PURPOSE

We investigated the neurorestorative effects and underlying mechanisms of stroke treatment with human umbilical cord blood cells (HUCBCs) in Type one diabetes mellitus (T1DM) rats.

METHODS

Type one diabetes mellitus rats were subjected to middle cerebral artery occlusion (MCAo) and 24 h later were treated with: (1) phosphate-buffered-saline; (2) HUCBCs. Brain endothelial cells (MBECs) were cultured and capillary tube formation was measured.

RESULTS

Human umbilical cord blood cells treatment significantly improved functional outcome and promoted white matter (WM) remodeling, as identified by Bielschowsky silver, Luxol fast blue and SMI-31 expression, increased oligodendrocyte progenitor cell and oligodendrocyte density after stroke in T1DM rats. HUCBC also promoted vascular remodeling, evident from enhanced vascular and arterial density and increased artery diameter, and decreased blood-brain barrier leakage. HUCBC treatment also increased Angiopoietin-1 and decreased receptor for advanced glycation end-products (RAGE) expression compared to T1DM-MCAo control. In vitro analysis of MBECs demonstrated that Ang1 inversely regulated RAGE expression. HUCBC and Ang1 significantly increased capillary tube formation and decreased inflammatory factor expression, while anti-Ang1 attenuated HUCBC-induced tube formation and antiinflammatory effects.

CONCLUSION

Human umbilical cord blood cells is an effective neurorestorative therapy in T1DM-MCAo rats and the enhanced vascular and WM remodeling and associated functional recovery after stroke may be attributed to increasing Angiopoietin-1 and decreasing RAGE.

Neurorestorative therapy for stroke

Ischemic stroke is responsible for many deaths and long-term disability world wide. Development of effective therapy has been the target of intense research. Accumulating preclinical literature has shown that substantial functional improvement after stroke can be achieved using subacutely administered cell-based and pharmacological therapies. This review will discuss some of the latest findings on bone marrow-derived mesenchymal stem cells (BMSCs), human umbilical cord blood cells, and off-label use of some pharmacological agents, to promote recovery processes in the sub-acute and chronic phases following stroke. This review paper also focuses on molecular mechanisms underlying the cell-based and pharmacological restorative processes, which enhance angiogenesis, arteriogenesis, neurogenesis, and white matter remodeling following cerebral ischemia as well as an analysis of the interaction/coupling among these restorative events. In addition, the role of microRNAs mediating the intercellular communication between exogenously administered cells and parenchymal cells, and their effects on the regulation of angiogenesis and neuronal progenitor cell proliferation and differentiation, and brain plasticity after stroke are described.

Hyperglycemia, acute ischemic stroke, and thrombolytic therapy

Ischemic stroke is a leading cause of disability and is considered now the fourth leading cause of death. Many clinical trials have shown that stroke patients with acute elevation in blood glucose at onset of stroke suffer worse functional outcomes, longer in-hospital stay, and higher mortality rates. The only therapeutic hope for these patients is the rapid restoration of blood flow to the ischemic tissue through intravenous administration of the only currently proven effective therapy, tissue plasminogen activator (tPA). However, even this option is associated with the increased risk of intracerebral hemorrhage. Nonetheless, the underlying mechanisms through which hyperglycemia (HG) and tPA worsen the neurovascular injury after stroke are not fully understood. Accordingly, this review summarizes the latest updates and recommendations about the management of HG and coadministration of tPA in a clinical setting while focusing more on the various experimental models studying (1) the effect of HG on stroke outcomes, (2) the potential mechanisms involved in worsening the neurovascular injury, (3) the different therapeutic strategies employed to ameliorate the injury, and finally, (4) the interaction between HG and tPA. Developing therapeutic strategies to reduce the hemorrhage risk with tPA in hyperglycemic setting is of great clinical importance. This can best be achieved by conducting robust preclinical studies evaluating the interaction between tPA and other therapeutics in order to develop potential therapeutic strategies with high translational impact.

Niaspan attenuates the adverse effects of bone marrow stromal cell treatment of stroke in type one diabetic rats

AIMS

Our previous studies have found that bone-marrow-stromal cells (BMSC) therapy improves functional recovery after stroke in non-diabetic rats while increases brain hemorrhage and induces arteriosclerosis-like changes in type-one-diabetic (T1DM) rats. Niaspan treatment of stroke increases vascular stabilization, decreases brain hemorrhage and blood-brain-barrier (BBB) leakage in T1DM rats. We therefore tested the hypothesis that combination therapy of BMSC with Niaspan attenuates the side effects of BMSC monotherapy in T1DM rats.

METHODS

T1DM-rats induced by streptozotocin were subjected to 2 hours of middle-cerebral-artery occlusion (MCAo) and treated with: 1) PBS; 2) BMSC (5×10(6)); 3) Niaspan (40 mg/kg) daily for 14 days; 4) BMSC (5×10(6)) +Niaspan (40 mg/kg, daily for 14 days) combination starting at 24 hours after MCAo. All rats were monitored for 14 days.

RESULTS

Combination BMSC+Niaspan treatment of T1DM-MCAo rats did not increase brain hemorrhage, and significantly decreased BBB leakage and vascular arteriosclerosis-like changes as well as decreased Angiogenin, matrix metalloproteinase 9 (MMP9) and ED1 expression in ischemic brain and internal-carotid-artery compared to non-treatment control and BMSC monotherapy animals.

CONCLUSIONS

Combination therapy using BMSC with Niaspan decreases BBB leakage and cerebral arteriosclerosis-like changes. These beneficial effects may be attributed to the decreased expression of Angiogenin, MMP9 and ED1.

Combination BMSC and Niaspan treatment of stroke enhances white matter remodeling and synaptic protein expression in diabetic rats

Objective

White matter remodeling plays an important role in neurological recovery after stroke. Bone marrow stromal cells (BMSCs) and Niaspan, an agent which increases high density lipoprotein (HDL), each induces neurorestorative effects and promotes white matter remodeling after stroke in non-diabetic rats. In this study, we test whether combination of BMSCs with Niaspan induces an enhanced white matter remodeling in the ischemic brain of diabetic rats.

Research design and methods

Type-1 diabetes (T1DM) rats were subjected to transient middle cerebral artery occlusion (MCAo) and treated with or without BMSCs; Niaspan; and the combination of BMSCs + Niaspan daily for 14 days after MCAo. Immunostaining for white matter remodeling and synaptic protein expression including NG2; CNPase; BS (Bielschowsky silver); LFB (luxol fast blue); Synaptophysin and SMI-31 immunostaining were performed.

Results

BMSC monotherapy did not regulate NG2 and CNPase expression compared to T1DM control rats. Both, combination of BMSCs + Niaspan treatment, and Niaspan monotherapy significantly increase NG2 and CNPase expression compared to T1DM control. While combination BMSC+Niaspan, BMSC monotherapy and Niaspan monotherapy groups all increase BS, LFB, synaptophysin, and SMI-31 expression in the ischemic brain compared to T1DM-MCAo control. In addition, the combination treatment significantly enhances LFB, SMI-31, and Synaptophysin expression compared to BMSC monotherapy.

Conclusions

Combination treatment of stroke with BMSCs and Niaspan in T1DM rats increases white matter remodeling and additively increases BMSC monotherapy induced myelination and synaptic plasticity after stroke in T1DM rats.

The role of astrocytes in mediating exogenous cell-based restorative therapy for stroke

Astrocytes have not been a major therapeutic target for the treatment of stroke, with most research emphasis on the neuron. Given the essential role that astrocytes play in maintaining physiological function of the central nervous system and the very rapid and sensitive reaction astrocytes have in response to cerebral injury or ischemic insult, we propose to replace the neurocentric view for treatment with a more nuanced astrocytic centered approach. In addition, after decades of effort in attempting to develop neuroprotective therapies, which target reduction of the ischemic lesion, there are no effective clinical treatments for stroke, aside from thrombolysis with tissue plasminogen activator, which is used in a small minority of patients. A more promising therapeutic approach, which may affect nearly all stroke patients, may be in promoting endogenous restorative mechanisms, which enhance neurological recovery. A focus of efforts in stimulating recovery post stroke is the use of exogenously administered cells. The present review focuses on the role of the astrocyte in mediating the brain network, brain plasticity, and neurological recovery post stroke. As a model to describe the interaction of a restorative cell-based therapy with astrocytes, which drives recovery from stroke, we specifically highlight the subacute treatment of stroke with multipotent mesenchymal stromal cell therapy.

Delayed administration of a PTEN inhibitor BPV improves functional recovery after experimental stroke

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) inhibitors administered prior to or immediately after experimental stroke confer acute neuroprotection. However, it remains unclear if delayed treatment with a PTEN inhibitor improves long-term functional recovery after stroke. We addressed the issue in this study. Adult male mice were subjected to 1h of middle cerebral artery occlusion (MCAO) followed by treatment with a well-established PTEN inhibitor BPV or saline daily for 14 days, starting at 24h after MCAO. Functional recovery was assessed with behavioral tests and acute infarct volumes were analyzed histologically. Delayed BPV treatment did not reduce infarction during the acute phase, but significantly improved long-term functional recovery after MCAO. Since PTEN is a critical intrinsic inhibitory factor in axonal regeneration, we further examined BPV effects on axonal densities following MCAO using bielschowsky silver staining and immunohistochemistry with antibodies against myelin basic protein. Delayed BPV treatment significantly increased axon densities in the ischemic brain at 14 days after MCAO. Moreover, PTEN expression persistently remained high in the ischemic brain over 14 days after MCAO, and BPV treatment increased post-ischemic activation of Akt and mTOR in the ischemic brain. Akt and mTOR activation are the well-established cascades downstream to PTEN inhibition and have been shown to contribute to post-injury axonal regrowth in response to PTEN inhibition. Consistently, in an in vitro neuronal ischemia model, BPV enhanced axonal outgrowth of primary cortical neurons after oxygen-glucose deprivation and the enhancing effects were abolished by Akt/mTOR inhibition. In conclusion, delayed BPV treatment improved functional recovery from experimental stroke possibly via enhancing axonal growth and Akt/mTOR activation contributed to BPV-enhanced post-stroke axon growth.