Mechanism of Action and Translational Potential of (S)-Meclizine in Preemptive Prophylaxis Against Stroke

BACKGROUND

Mild chemical inhibition of mitochondrial respiration can confer resilience against a subsequent stroke or myocardial infarction, also known as preconditioning. However, the lack of chemicals that can safely inhibit mitochondrial respiration has impeded the clinical translation of the preconditioning concept. We previously showed that meclizine, an over-the-counter antivertigo drug, can toggle metabolism from mitochondrial respiration toward glycolysis and protect against ischemia-reperfusion injury in the brain, heart, and kidney. Here, we examine the mechanism of action of meclizine and report the efficacy and improved safety of the (S) enantiomer.

METHODS

We determined the anoxic depolarization latency, tissue and neurological outcomes, and glucose uptake using micro-positron emission tomography after transient middle cerebral artery occlusion in mice pretreated (-17 and -3 hours) with either vehicle or meclizine. To exclude a direct effect on tissue excitability, we also examined spreading depression susceptibility. Furthermore, we accomplished the chiral synthesis of (R)- and (S)-meclizine and compared their effects on oxygen consumption and histamine H1 receptor binding along with their brain concentrations.

RESULTS

Micro-positron emission tomography showed meclizine increases glucose uptake in the ischemic penumbra, providing the first in vivo evidence that the neuroprotective effect of meclizine indeed stems from its ability to toggle metabolism toward glycolysis. Consistent with reduced reliance on oxidative phosphorylation to sustain the metabolism, meclizine delayed anoxic depolarization onset after middle cerebral artery occlusion. Moreover, the (S) enantiomer showed reduced H1 receptor binding, a dose-limiting side effect for the racemate, but retained its effect on mitochondrial respiration. (S)-meclizine was at least as efficacious as the racemate in delaying anoxic depolarization onset and decreasing infarct volumes after middle cerebral artery occlusion.

CONCLUSIONS

Our data identify (S)-meclizine as a promising new drug candidate with high translational potential as a chemical preconditioning agent for preemptive prophylaxis in patients with high imminent stroke or myocardial infarction risk.

Artificial DNA Framework Channel Modulates Antiapoptotic Behavior in Ischemia-Stressed Cells via Destabilizing Promoter G-Quadruplex

Regulating folding/unfolding of gene promoter G-quadruplexes (G4s) is important for understanding the topological changes in genomic DNAs and the biological effects of such changes on important cellular events. Although many G4-stabilizing ligands have been screened out, effective G4-destabilizing ligands are extremely rare, posing a great challenge for illustrating how G4 destabilization affects gene function in living cells under stress, a long-standing question in neuroscience. Herein, we report a distinct methodology able to destabilize gene promoter G4s in ischemia-stressed neural cells by mitigating the ischemia-induced accumulation of intracellular K+ with an artificial membrane-spanning DNA framework channel (DFC). We also show that ischemia-triggered K+ influx is positively correlated to anomalous stabilization of promoter G4s and downregulation of Bcl-2, an antiapoptotic gene with neuroprotective effects against ischemic injury. Intriguingly, the DFC enables rapid transmembrane transport of excessive K+ mediated by the internal G4 filter, leading to the destabilization of endogenous promoter G4 in Bcl-2 and subsequent turnover of gene expression at both transcription and translation levels under ischemia. Consequently, this work enriches our understanding of the biological roles of endogenous G4s and may offer important clues to study the cellular behaviors in response to stress.

Induced pluripotent stem cell-derived extracellular vesicles enriched with miR-126 induce proangiogenic properties and promote repair of ischemic tissue

Emerging evidence suggests that stem cell-derived extracellular vesicles (EVs) may induce pro-regenerative effects in ischemic tissues by delivering bioactive molecules, including microRNAs. Recent studies have also shown pro-regenerative benefits of EVs derived from induced pluripotent stem (iPS) cells. However, the underlying mechanisms of EV benefits and the role of their transferred regulatory molecules remain incompletely understood. Accordingly, we investigated the effects of human iPS-derived EVs (iPS-EVs) enriched in proangiogenic miR-126 (iPS-miR-126-EVs) on functional properties of human endothelial cells (ECs) in vitro. We also examined the outcomes following EV injection in a murine model of limb ischemia in vivo. EVs were isolated from conditioned media from cultures of unmodified and genetically modified human iPS cells overexpressing miR-126. The iPS-miR-126-EVs were enriched in miR-126 when compared with control iPS-EVs and effectively transferred miR-126 along with other miRNAs to recipient ECs improving their functional properties essential for ischemic tissue repair, including proliferation, metabolic activity, cell survival, migration, and angiogenic potential. Injection of iPS-miR-126-EVs in vivo in a murine model of acute limb ischemia promoted angiogenesis, increased perfusion, and enhanced functional recovery. These observations corresponded with elevated expression of genes for several proangiogenic factors in ischemic tissues following iPS-miR-126-EV transplantation. These results indicate that innate pro-regenerative properties of iPS-EVs may be further enhanced by altering their molecular composition via controlled genetic modifications. Such iPS-EVs overexpressing selected microRNAs, including miR-126, may represent a novel acellular tool for therapy of ischemic tissues in vivo.

Ocimum sanctum [Tulsi] as a Potential Immunomodulator for the Treatment of Ischemic Injury in the Brain

Stroke causes brain damage and is one of the main reasons for death. Most survivors of stroke face long-term physical disabilities and cognitive dysfunctions. In addition, they also have persistent emotional and behavioral changes. The two main treatments that are effective are reperfusion with recombinant tissue plasminogen activator and recanalization of penumbra using mechanical thrombectomy. However, these treatments are suitable only for a few patients due to limitations such as susceptibility to hemorrhage and the requirement for administering tissue plasminogen activators within the short therapeutic window during the early hours following a stroke. The paucity of interventions and treatments could be because of the multiple pathological mechanisms induced in the brain by stroke. The ongoing immune response following stroke has been attributed to the worsening brain injury. Hence, novel compounds with immunomodulatory properties that could improve the outcome of stroke patients are required. Natural compounds and medicinal herbs with anti-inflammatory activities and having minimal or no adverse systemic effect could be beneficial in treating stroke. Ocimum sanctum is a medicinal herb that can be considered an effective therapeutic option for ischemic brain injury. Ocimum sanctum, commonly known as holy basil or "Tulsi," is mentioned as the "Elixir of Life" for its healing powers. Since antiquity, Tulsi has been used in the Ayurvedic and Siddha medical systems to treat several diseases. It possesses immuno-modulatory activity, which can alter cellular and humoral immune responses. Tulsi can be considered a potential option as an immuno-modulator for treating various diseases, including brain stroke. In this review, we will focus on the immunomodulatory properties of Tulsi, specifically its effect on both innate and adaptive immunity, as well as its antioxidant and antiinflammatory properties, which could potentially be effective in treating ongoing immune reactions following ischemic brain injury.

Ozanimod differentially preserves human cerebrovascular endothelial barrier proteins and attenuates matrix metalloproteinase-9 activity following in vitro acute ischemic injury

Endothelial integrity is critical in mitigating a vicious cascade of secondary injuries following acute ischemic stroke (AIS). Matrix metalloproteinase-9 (MMP-9), a contributor to endothelial integrity loss, is elevated during stroke and is associated with worsened stroke outcome. We investigated the FDA-approved selective sphingosine-1-phosphate receptor 1 (S1PR1) ligand, ozanimod, on the regulation/activity of MMP-9 as well as endothelial barrier components [platelet endothelial cell adhesion molecule 1 (PECAM-1), claudin-5, and zonula occludens 1 (ZO-1)] in human brain microvascular endothelial cells (HBMECs) following hypoxia plus glucose deprivation (HGD). We previously reported that S1PR1 activation improves HBMEC integrity; however, mechanisms underlying S1PR1 involvement in endothelial cell barrier integrity have not been clearly elucidated. We hypothesized that ozanimod would attenuate an HGD-induced increase in MMP-9 activity that would concomitantly attenuate the loss of integral barrier components. Male HBMECs were treated with ozanimod or vehicle and exposed to 3 h of normoxia (21% O2) or HGD (1% O2). Immunoblotting, zymography, qRT-PCR, and immunocytochemical labeling techniques assessed processes related to MMP-9 and barrier markers. We observed that HGD acutely increased MMP-9 activity and reduced claudin-5 and PECAM-1 levels, and ozanimod attenuated these responses. In situ analysis, via PROSPER, suggested that attenuation of MMP-9 activity may be a primary factor in maintaining these integral barrier proteins. We also observed that HGD increased intracellular mechanisms associated with augmented MMP-9 activation; however, ozanimod had no effect on these select factors. Thus, we conclude that ozanimod has the potential to attenuate HGD-mediated decreases in HBMEC integrity in part by decreasing MMP-9 activity as well as preserving barrier properties.NEW & NOTEWORTHY We have identified a potential novel mechanism by which ozanimod, a selective sphingosine-1-phosphate receptor 1 (S1PR1) agonist, attenuates hypoxia plus glucose deprivation (HGD)-induced matrix metalloproteinase-9 (MMP-9) activity and disruptions in integral human brain endothelial cell barrier proteins. Our results suggest that ischemic-like injury elicits increased MMP-9 activity and alterations of barrier integrity proteins in human brain microvascular endothelial cells (HBMECs) and that ozanimod via S1PR1 attenuates these HGD-induced responses, adding to its therapeutic potential in cerebrovascular protection during the acute phase of ischemic stroke.

Non-invasive intradialytic percutaneous perfusion monitoring: a view to the heart through the skin

Introduction

The life-sustaining treatment of hemodialysis (HD) induces recurrent and cumulative systemic circulatory stress resulting in cardiovascular injury. These recurrent insults compound preexisting cardiovascular sequalae leading to the development of myocardial injury and resulting in extremely high morbidity/mortality. This is largely a consequence of challenged microcirculatory flow within the myocardium (evidenced by detailed imaging-based studies). Currently, monitoring during HD is performed at the macrovascular level. Non-invasive monitoring of organ perfusion would allow the detection and therapeutic amelioration of this pathophysiological response to HD. Non-invasive percutaneous perfusion monitoring of the skin (using photoplethysmography-PPG) has been shown to be predictive of HD-induced myocardial stunning (a consequence of segmental ischemia). In this study, we extended these observations to include a dynamic assessment of skin perfusion during HD compared with directly measured myocardial perfusion during dialysis and cardiac contractile function.

Methods

We evaluated the intradialytic microcirculatory response in 12 patients receiving conventional HD treatments using continuous percutaneous perfusion monitoring throughout HD. Cardiac echocardiography was performed prior to the initiation of HD, and again at peak-HD stress, to assess the development of regional wall motion abnormalities (RWMAs). Myocardial perfusion imaging was obtained at the same timepoints (pre-HD and peak-HD stress), utilizing intravenous administered contrast and a computerized tomography (CT)-based method. Intradialytic changes in pulse strength (derived from PPG) were compared with the development of HD-induced RWMAs (indicative of myocardial stunning) and changes in myocardial perfusion.

Results

We found an association between the lowest pulse strength reduction (PPG) and the development of RWMAs (p = 0.03) and also with changes in global myocardial perfusion (CT) (p = 0.05). Ultrafiltration rate (mL/kg/hour) was a significant driver of HD-induced circulatory stress [(associated with the greatest pulse strength reduction (p = 0.01), a reduction in global myocardial perfusion (p = 0.001), and the development of RWMAs (p = 0.03)].

Discussion

Percutaneous perfusion monitoring using PPG is a useful method of assessing intradialytic hemodynamic stability and HD-induced circulatory stress. The information generated at the microcirculatory level of the skin is reflective of direct measures of myocardial perfusion and the development of HD-induced myocardial stunning. This approach for the detection and management of HD-induced cardiac injury warrants additional evaluation.

Anti-Neuroinflammatory Effects of the Human Milk Oligosaccharide, 2'-Fucosyllactose, Exerted via Modulation of M2 Microglial Activation in a Mouse Model of Ischemia-Reperfusion Injury

Cerebral ischemic stroke is one of the leading causes of death and disability worldwide. 2'-fucosyllactose (2'-FL), a human milk oligosaccharide, exerts anti-inflammatory effects and plays a protective role in arterial thrombosis; however, its role in ischemic stroke remains unclear. This study aimed to investigate the neuroprotective effects of 2'-FL and its potential mechanisms in a mouse model of ischemic stroke. Neurological score and behavior tests revealed that 2'-FL promoted the recovery of neurological deficits and motor function in middle cerebral artery occlusion (MCAO) mice, and that 2'FL led to a reduction in the size of cerebral infarct. Biochemical studies showed that administration of 2'-FL led to a reduction of reactive oxygen species (ROS)-related products in the brain of MCAO mice. 2'-FL upregulated IL-10 and downregulated TNF-α level. In addition, 2'-FL enhanced M2-type microglial polarization and upregulated CD206 expression at 7 days after MCAO. At 3 days after MCAO, 2'-FL increased IL-4 levels and activated STAT6. Our data show that 2'-FL reduced the neurological symptoms of ischemic stroke and ROS accumulation in the brain through IL-4/STAT6-dependent M2-type microglial polarization in MCAO mice. These results demonstrate that 2'-FL is a potentially effective therapeutic agent for ischemic stroke.

Rosavin protects the blood-brain barrier against ischemia/reperfusion-induced cerebral injury by regulating MAPK-mediated MMPs pathway

Ischemia-reperfusion (I/R) injury is a common pathophysiological condition in ischemic stroke, involving various pathophysiological events, such as inflammation, cytotoxicity, neuronal loss and disruption of the blood-brain barrier (BBB). Rosavin is the major bioactive ingredient of Rhodiola Rosea L. with multiple therapeutic effects. The purpose of this was to investigate the role of rosavin in I/R-induced cerebral injury. A cell oxygen-glucose deprivation and reoxygenation (OGD/R) model and a mouse middle cerebral artery occlusion (MCAO) model were established to induce I/R injury in vitro and in vivo, respectively. MCAO-treated mice and OGD/R-challenged human brain microvascular endothelial cells (HBMVECs) were administrated with or without rosavin at various concentrations. Rosavin-treated mice showed reduced infarct volume, neuronal loss and neuronal cytotoxicity in I/R-injured brains. Rosavin treatment downregulated the expression of pro-inflammatory cytokines, reduced apoptosis and inhibited the activation of nuclear factor κ B in I/R-injured mice and HBMVECs. Administration with rosavin also alleviated mouse brain oedema and upregulated tight junction proteins in mouse brains after I/R injury, suggesting that rosavin protected mice against I/R-induced BBB disruption. Further analysis revealed that rosavin reduced the BBB permeability in I/R-injured mice and HBMVECs by inhibiting autophagy. Moreover, rosavin intervention inhibited I/R injury-induced activation of the mitogen-activated protein kinase (MAPK) pathway and upregulation of matrix metalloproteinases in both mouse and cell models. In conclusion, rosavin protects the BBB against I/R injury possibly by regulating the MAPK pathway. The above results provide a rationale for further exploration of rosavin as a therapeutic candidate for cerebral I/R injury.

Neural cortical organoids from self-assembling human iPSC as a model to investigate neurotoxicity in brain ischemia

Brain ischemia is a common acute injury resulting from impaired blood flow to the brain. Translation of effective drug candidates from experimental models to patients has systematically failed. The use of human induced pluripotent stem cells (iPSC) offers new opportunities to gain translational insights into diseases including brain ischemia. We used a human 3D self-assembling iPSC-derived model (human cortical organoids, hCO) to characterize the effects of ischemia caused by oxygen-glucose deprivation (OGD). hCO exposed to 2 h or 8 h of OGD had neuronal death and impaired neuronal network complexity, measured in whole-mounting microtubule-associated protein 2 (MAP-2) immunostaining. Neuronal vulnerability was reflected by a reduction in MAP-2 mRNA levels, and increased release of neurofilament light chain (NfL) in culture media, proportional to OGD severity. Glial fibrillary acidic protein (GFAP) gene or protein levels did not change in hCO, but their release in medium increased after prolonged OGD. In conclusion, this human 3D iPSC-based in vitro model of brain ischemic injury is characterized by marked neuronal injury reflected by the release of the translational biomarker NfL which is relevant for testing neuroprotective strategies.

TRPC Channels in the Physiology and Pathophysiology of the Renal Tubular System: What Do We Know?

The study of transient receptor potential (TRP) channels has dramatically increased during the past few years. TRP channels function as sensors and effectors in the cellular adaptation to environmental changes. Here, we review literature investigating the physiological and pathophysiological roles of TRPC channels in the renal tubular system with a focus on TRPC3 and TRPC6. TRPC3 plays a key role in Ca²⁺ homeostasis and is involved in transcellular Ca²⁺ reabsorption in the proximal tubule and the collecting duct. TRPC3 also conveys the osmosensitivity of principal cells of the collecting duct and is implicated in vasopressin-induced membrane translocation of AQP-2. Autosomal dominant polycystic kidney disease (ADPKD) can often be attributed to mutations of the PKD2 gene. TRPC3 is supposed to have a detrimental role in ADPKD-like conditions. The tubule-specific physiological functions of TRPC6 have not yet been entirely elucidated. Its pathophysiological role in ischemia-reperfusion injuries is a subject of debate. However, TRPC6 seems to be involved in tumorigenesis of renal cell carcinoma. In summary, TRPC channels are relevant in multiples conditions of the renal tubular system. There is a need to further elucidate their pathophysiology to better understand certain renal disorders and ultimately create new therapeutic targets to improve patient care.

High-impact opportunities to address ischemia: a focus on heart and circulatory research

Myocardial ischemic injury and its resolution are the key determinants of morbidity or mortality in heart failure. The cause and duration of ischemia in patients vary. Numerous experimental models and methods have been developed to define genetic, metabolic, molecular, cellular, and pathophysiological mechanisms, in addition to defining structural and functional deterioration of cardiovascular performance. The rapid rise of big data, such as single-cell analysis techniques with bioinformatics, machine learning, and neural networking, brings a new level of sophistication to our understanding of myocardial ischemia. This mini-review explores the multifaceted nature of ischemic injury in the myocardium. We highlight recent state-of-the-art findings and strategies to show new directions of high-impact approach to understanding myocardial tissue remodeling. This next age of heart and circulatory physiology research will be more comprehensive and collaborative to uncover the origin, progression, and manifestation of heart failure while strengthening novel treatment strategies.

Exogenous pericyte delivery protects the mouse kidney from chronic ischemic injury

Pericytes are considered reparative mesenchymal stem cell-like cells, but their ability to ameliorate chronic ischemic kidney injury is unknown. We hypothesized that pericytes would exhibit renoprotective effects in murine renal artery stenosis (RAS). Porcine kidney-derived pericytes (5 × 105) or vehicle were injected into the carotid artery 2 wk after the induction of unilateral RAS in mice. The stenotic kidney glomerular filtration rate and tissue oxygenation were measured 2 wk later using magnetic resonance imaging. We subsequently compared kidney oxidative stress, inflammation, apoptosis, fibrosis, and systemic levels of oxidative and inflammatory cytokines. Treatment of xenogeneic pericytes ameliorated the RAS-induced loss of perfusion, glomerular filtration rate, and atrophy in stenotic kidneys and restored cortical and medullary oxygenation but did not blunt hypertension. Ex vivo, pericytes injection partially mitigated RAS-induced renal inflammation, fibrosis, oxidative stress, apoptosis, and senescence. Furthermore, coculture with pericytes in vitro protected pig kidney-1 tubular cells from injury. In conclusion, exogenous delivery of renal pericytes protects the poststenotic mouse kidney from ischemic injury, underscoring the therapeutic potential role of pericytes in subjects with ischemic kidney disease.NEW & NOTEWORTHY Our study demonstrates a novel pericyte-based therapy for the injured kidney. The beneficial effect of pericyte delivery appears to be mediated by ameliorating oxidative stress, inflammation, cellular apoptosis, and senescence in the stenotic kidney and improved tissue hypoxia, vascular loss, fibrosis, and tubular atrophy. Our data may form the basis for pericyte-based therapy, and additional research studies are needed to gain further insight into their role in improving renal function.

Tunneling nanotubes and mesenchymal stem cells: New insights into the role of melatonin in neuronal recovery

Efficient cell-to-cell communication is essential for tissue development, homeostasis, and the maintenance of cellular functions after injury. Tunneling nanotubes (TNTs) have emerged as a new important method of cell-to-cell communication. TNTs are primarily established between stressed and unstressed cells and can transport a variety of cellular components. Mitochondria are important trafficked entities through TNTs. Transcellular mitochondria transfer permits the incorporation of healthy mitochondria into the endogenous network of recipient cells, changing the bioenergetic profile and other functional properties of the recipient and may allow the recipient cells to recuperate from apoptotic processes and return to a normal operating state. Mesenchymal cells (MSCs) can form TNTs and transfer mitochondria and other constituents to target cells. This occurs under both physiological and pathological conditions, leading to changes in cellular energy metabolism and functions. This review summarizes the newly described capacity of melatonin to improve mitochondrial fusion/fission dynamics and promote TNT formation. This new evidence suggests that melatonin's protective effects could be attributed to its ability to prevent mitochondrial damage in injured cells, reduce senescence, and promote anastasis, a natural cell recovery phenomenon that rescues cells from the brink of death. The modulation of these new routes of intercellular communication by melatonin could play a key role in increasing the therapeutic potential of MSCs.

A Long-Term Clearing Cranial Window for Longitudinal Imaging of Cortical and Calvarial Ischemic Injury through the Intact Skull

Skull is a reservoir for supplying immune cells that mediate brain immune surveillance. However, during intravital optical imaging of brain, conventional cranial windows requiring skull thinning or removal disrupt brain immunity integrity. Here, a novel long-term clearing cranial window (LCCW) based on the intact skull, dedicated to chronic skull transparency maintenance, is proposed. It significantly improves optical imaging resolution and depth, by which the cortical and calvarial vascular injury and regeneration processes after ischemic injury are longitudinally monitored in awake mice. Results show that calvarial blood vessels recover earlier than the cortex. And the transcriptome analysis reveals that gene expression patterns and immune cells abundances exist substantial differences between brain and skull after ischemic injury, which may be one of the causes for the time lag between their vascular recovery. These findings bring great enlightenment to vascular regeneration and reconstruction. Moreover, LCCW provides a minimally invasive approach for imaging the brain and skull bone marrow.

Gastrodin protects retinal ganglion cells from ischemic injury by activating phosphatidylinositol 3-kinase/protein kinase B/nuclear factor erythroid 2-related factor 2 (PI3K/AKT/Nrf2) signaling pathway

Glaucoma is a progressive optic neuropathy and improper treatment may cause irreversible damage to visual function. Gastrodin is an effective active substance extracted from Gastrodia elata and possesses antioxidant as well as anti-inflammatory properties. However, the therapeutic potential of gastrodin for retinal ischemia/reperfusion (I/R) injury remains unclear. We adopted oxygen and glucose deprivation/reoxygenation (OGD/R) to induce R28 cells with the aim of simulating glaucomatous neurodegeneration. CCK-8 analysis and TUNEL were applied for examining cell proliferation and apoptosis . In addition, RT-qPCR and ELISA were performed to test the releases of inflammatory factors in cells . Related indicators of intracellular oxidative stress and ROS production were detected by corresponding kits. Moreover, western blot was applied to assay the expressions of PI3K/AKT/Nrf2 pathway-related proteins. OGD/R induction contributed to the decreased cell viability and reduced Bcl-2 protein expression, while the protein contents of Bax, Cyto-C, c-caspase 9 and c-PARP as well as ROS production were ascended. The co-treatment of hypoxia and gastrodin greatly improved R28 cell viability but effectively suppressed cell apoptosis, ROS level and the releases of OGD/R-induced inflammatory factors as well as oxidative stress. In addition, OGD/R stimulation reduced Nrf2, accompanied by a decrease in the phosphorylation levels of PI3K and AKT. Gastrodin significantly promoted the activation of PI3K/AKT/Nrf2 signaling pathway in R28 cells, which was then counteracted by PI3K/AKT inhibitors. In conclusion, the present study suggested that gastrodin has a protective effect on OGD/R-induced R28 cell injury, which is achieved through the activation of the PI3K/AKT/Nrf2 signaling pathway.

An update on the functional roles of long non‑coding RNAs in ischemic injury (Review)

Ischemic injuries result from ischemia and hypoxia in cells. Tissues and organs receive an insufficient supply of nutrients and accumulate metabolic waste, which leads to the development of inflammation, fibrosis and a series of other issues. Ischemic injuries in the brain, heart, kidneys, lungs and other organs can cause severe adverse effects. Acute renal ischemia induces acute renal failure, heart ischemia induces myocardial infarction and cerebral ischemia induces cerebrovascular accidents, leading to loss of movement, consciousness and possibly, life-threatening disabilities. Existing evidence suggests that long non-coding RNAs (lncRNAs) are regulatory sequences involved in transcription, post-transcription, epigenetic regulation and multiple physiological processes. lncRNAs have been shown to be differentially expressed following ischemic injury, with the severity of the ischemic injury being affected by the upregulation or downregulation of certain types of lncRNA. The present review article provides an extensive summary of the functional roles of lncRNAs in ischemic injury, with a focus on the brain, heart, kidneys and lungs. The present review mainly summarizes the functional roles of lncRNA MALAT1, lncRNA MEG3, lncRNA H19, lncRNA TUG1, lncRNA NEAT1, lncRNA AK139328 and lncRNA CAREL, among which lncRNA MALAT1, in particular, plays a crucial role in ischemic injury and is currently a hot research topic.

Mechanism-Based Cardiac Regeneration Strategies in Mammals

Heart failure in adults is a leading cause of morbidity and mortality worldwide. It can arise from a variety of diseases, with most resulting in a loss of cardiomyocytes that cannot be replaced due to their inability to replicate, as well as to a lack of resident cardiomyocyte progenitor cells in the adult heart. Identifying and exploiting mechanisms underlying loss of developmental cardiomyocyte replicative capacity has proved to be useful in developing therapeutics to effect adult cardiac regeneration. Of course, effective regeneration of myocardium after injury requires not just expansion of cardiomyocytes, but also neovascularization to allow appropriate perfusion and resolution of injury-induced inflammation and interstitial fibrosis, but also reversal of adverse left ventricular remodeling. In addition to overcoming these challenges, a regenerative therapy needs to be safe and easily translatable. Failure to address these critical issues will delay the translation of regenerative approaches. This review critically analyzes current regenerative approaches while also providing a framework for future experimental studies aimed at enhancing success in regenerating the injured heart.

Endothelial GABBR2 Regulates Post-ischemic Angiogenesis by Inhibiting the Glycolysis Pathway

Purpose: Angiogenesis post-ischemia plays an essential role in preventing ischemic damage to tissue by improving the blood recovery. Determining the regulatory mechanism of ischemic angiogenesis, therefore, could provide effective therapeutics for ischemic injury. Materials and Methods: The RNA sequencing (RNA-seq) database was used to predict the association of gamma-aminobutyric acid type B receptor subunit 2 (GABBR2) with endothelial-specific expression. The role of GABBR2 in angiogenesis was verified in vitro by downregulating GABBR2 in human umbilical vein endothelial cells (HUVECs) with lentiviral vectors. Besides, the in vivo effect of GABBR2 on the blood recovery of an ischemic hindlimb was demonstrated by establishing a hindlimb ischemia model in normal and GABBR2 adenoviral vector-infected mice. Then, the mobilization of endothelial progenitor cells (EPCs) in peripheral blood post-ischemia was determined by flow cytometry. Finally, the XF analyzer and Western blot were used to determine the effect of GABBR2 on endothelial metabolism. Results: The RNA-seq results indicated a strong association between GABBR2 and endothelial revascularization, and the upregulation of GABBR2 was detected in both hypoxia-treated HUVECs and ischemic mouse hindlimb. Hypoxia treatment for 6 h increased the proliferation, migration, and tube formation of HUVECs, which were inhibited by GABBR2 knockdown. Additionally, GABBR2 downregulation significantly decreased the blood flow recovery of mouse ischemic hindlimb. The expressions of the EPC markers CD34⁺ and CD133⁺ significantly decreased in the peripheral blood in hindlimb post-ischemia. Mechanically, glycolysis-dominated metabolism of HUVECs was compromised by GABBR2 knockdown. Evidences of the decreased expressions of HKII, PFKFB3, and PKM1 also supported the compromised glycolysis induced by GABBR2 downregulation. Conclusion: Our study demonstrated that GABBR2 regulated angiogenesis post-ischemia by inhibiting the glycolysis pathway.

Restoration of Visual Function and Cortical Connectivity After Ischemic Injury Through NeuroD1-Mediated Gene Therapy

Neural circuits underlying brain functions are vulnerable to damage, including ischemic injury, leading to neuronal loss and gliosis. Recent technology of direct conversion of endogenous astrocytes into neurons in situ can simultaneously replenish the neuronal population and reverse the glial scar. However, whether these newly reprogrammed neurons undergo normal development, integrate into the existing neuronal circuit, and acquire functional properties specific for this circuit is not known. We investigated the effect of NeuroD1-mediated in vivo direct reprogramming on visual cortical circuit integration and functional recovery in a mouse model of ischemic injury. After performing electrophysiological extracellular recordings and two-photon calcium imaging of reprogrammed cells in vivo and mapping the synaptic connections formed onto these cells ex vivo, we discovered that NeuroD1 reprogrammed neurons were integrated into the cortical microcircuit and acquired direct visual responses. Furthermore, following visual experience, the reprogrammed neurons demonstrated maturation of orientation selectivity and functional connectivity. Our results show that NeuroD1-reprogrammed neurons can successfully develop and integrate into the visual cortical circuit leading to vision recovery after ischemic injury.

Testicular damage during cryopreservation and transplantation

The aim of this study is to do a study of cryoinjury and ischaemic injury on testicular graft during cryopreservation and transplantation. According to time at 1, 3, 7 and 14 days after transplantation, the grafts were collected for immunohistochemistry assay for CD34 (blood vessel marker), VEGF (neoangiogenesis marker), caspase-3 (apoptosis marker) MAGE-A4 (germ cell marker). A significant increase was observed in the density of VEGF-positive blood vessels on day 3, reached a peak on day 7. On post-transplant day 3, a sharp increase occurred in the rate of spermatogonia-expressing caspase-3 until the day 7. At 14th day after transplantation, the spermatogonia number per round tubule of nonfrozen grafts was 41 ± 5.9% from that of fresh control tissues, while, in frozen-thawed grafts, the spermatogonia number per round tubule was 36.8 ± 4.6% from that of fresh control tissues. In testicular grafts, angiogenesis initiated reperfusion from day 3, and the formation of new blood vessel generally is completed about 7 days after transplantation. Angiogenesis in grafts after transplantation plays a crucial role in the restoration of function. Therefore, minimising ischaemic injury as well as improvement of cryopreservation protocols are needed to improve testicular graft after freezing, thawing and grafting.

A Cardiac Protection of Germinated Brown Rice During Cardiopulmonary Bypass Surgery and Simulated Myocardial Ischemia

Purpose

The potential cardio-protective property of germinated brown rice (GBR) has been revealed by ameliorating risk factors related to cardiovascular diseases. This study hypothesized that the combination of GBR and cardioplegic solution could protect the cardiomyocytes exposed to simulated ischemic reperfusion injury in vitro study and preserve cardiac function during cardiopulmonary bypass surgery in animal models.

Methods

Primary porcine cardiomyocytes were isolated and experimented cell viability against simulated ischemic reperfusion injury. In a cardiac surgical animal model, six pigs were randomly assigned to receive the two types of cardioplegic solution: i) St. Thomas cardioplegic solution (20 cc/kg); and ii) St. Thomas cardioplegic solution plus GBR (1 mg/kg). During open-heart surgery, the aorta was cross-clamped for 20 minutes, followed by reperfusion for 1 hour. Cardiopulmonary bypass parameters were recorded until the end of the procedure. Furthermore, hemodynamic parameters and arterial blood gas characteristics of animals among groups were monitored at different time points, including baseline before cardiopulmonary bypass (T1), during cardiopulmonary bypass (T2), during aortic clamp on (T3), and aortic clamp off (T4).

Results

Primarily, GBR cotreatment with cardioplegic solution essentially resulted in the improvement of cell viability in primary porcine cardiomyocytes against simulated ischemic reperfusion induction. The findings from cardiac surgery demonstrated that mean arterial pressure and heart rate are constantly stable in cardioplegic solution combined with the GBR group, while the trend of potassium and lactase concentration was decreased in the animals receiving GBR group. Consistently, all parameters from arterial blood gas showed better outcomes in animals receiving GBR; however, there were no statistically significant differences between groups, except hepatic enzymes.

Conclusion

Therefore, GBR might exert cardio-protective effects against ischemic reperfusion injury in the porcine cardiac surgery model due to anti-inflammatory response. These protective actions of GBR may explain the benefits gained from applying GBR products as a possible therapeutic supplement on cardiac diseases.

Role of a Heat Shock Transcription Factor and the Major Heat Shock Protein Hsp70 in Memory Formation and Neuroprotection

Heat shock proteins (Hsps) represent the most evolutionarily ancient, conserved, and universal system for protecting cells and the whole body from various types of stress. Among Hsps, the group of proteins with a molecular weight of 70 kDa (Hsp70) plays a particularly important role. These proteins are molecular chaperones that restore the native conformation of partially denatured proteins after exposure to proteotoxic forms of stress and are critical for the folding and intracellular trafficking of de novo synthesized proteins under normal conditions. Hsp70s are expressed at high levels in the central nervous system (CNS) of various animals and protect neurons from various types of stress, including heat shock, hypoxia, and toxins. Numerous molecular and behavioral studies have indicated that Hsp70s expressed in the CNS are important for memory formation. These proteins contribute to the folding and transport of synaptic proteins, modulate signaling cascades associated with synaptic activation, and participate in mechanisms of neurotransmitter release. In addition, HSF1, a transcription factor that is activated under stress conditions and mediates Hsps transcription, is also involved in the transcription of genes encoding many synaptic proteins, whose levels are increased in neurons under stress and during memory formation. Thus, stress activates the molecular mechanisms of memory formation, thereby allowing animals to better remember and later avoid potentially dangerous stimuli. Finally, Hsp70 has significant protective potential in neurodegenerative diseases. Increasing the level of endogenous Hsp70 synthesis or injecting exogenous Hsp70 reduces neurodegeneration, stimulates neurogenesis, and restores memory in animal models of ischemia and Alzheimer’s disease. These findings allow us to consider recombinant Hsp70 and/or Hsp70 pharmacological inducers as potential drugs for use in the treatment of ischemic injury and neurodegenerative disorders.

Ischemia Injury induces mPTP opening by reducing Sirt3

Mitochondrial permeability transition pore (mPTP) opening is critical to mitochondrial apoptosis during ischemic injury. Sirtuin 3 (Sirt3) is a mitochondrial deacetylase known to play a major role in stress resistance and cell death. Our previous studies have shown that Sirt3 activates superoxide dismutase 2 and forkhead box O3a to reduce cellular reactive oxygen species. However, it is unclear the interaction between Sirt3 and mPTP and the roles they play in ischemic stroke. We used the middle cerebral artery occlusion (MCAO) model, a mouse model of stroke, to examine Sirt3 and mPTP-related protein levels. We then applied lentivirus packaged Sirt3 overexpression in HT22 cells, a mouse hippocampal neuronal cell line, to investigate the underlying mechanism. We found Sirt3 protein level was decreased in the penumbra area in MCAO mice, along with an increase in mPTP related proteins, namely voltage-dependent anion channel 1 (VDAC1) and adenine nucleotide translocator 1 (ANT1). Sirt3 overexpression suppressed the increase in VDAC1, ANT1 and cleaved caspase 3 that were induced by the serum and glucose deprivation (SGD) condition. Our studies suggest that ischemic injury induced mPTP opening and apoptosis by reducing Sirt3. It helps to identify new therapeutic targets for ischemic stroke.

Ozanimod, an S1PR1 ligand, attenuates hypoxia plus glucose deprivation-induced autophagic flux and phenotypic switching in human brain VSM cells

Vascular smooth muscle (VSM) cell phenotypic expression and autophagic state are dynamic responses to stress. Vascular pathologies, such as hypoxemia and ischemic injury, induce a synthetic VSM phenotype and autophagic flux resulting in a loss of vascular integrity and VSM cell death respectfully. Both clinical pilot and experimental stroke studies demonstrate that sphingosine-1-phosphate receptor (S1PR) modulation improves stroke outcome; however, specific mechanisms associated with a beneficial outcome at the level of the cerebrovasculature have not been clearly elucidated. We hypothesized that ozanimod, a selective S1PR type 1 ligand, will attenuate VSM synthetic phenotypic expression and autophagic flux in primary human brain VSM cells following acute hypoxia plus glucose deprivation (HGD; in vitro ischemic-like injury) exposure. Cells were treated with ozanimod and exposed to normoxia or HGD. Crystal violet staining, standard immunoblotting, and immunocytochemical labeling techniques assessed cellular morphology, vacuolization, phenotype, and autophagic state. We observed that HGD temporally decreased VSM cell viability and concomitantly increased vacuolization, both of which ozanimod reversed. HGD induced a simultaneous elevation and reduction in levels of pro- and antiautophagic proteins respectfully, and ozanimod attenuated this response. Protein levels of VSM phenotypic biomarkers, smoothelin and SM22, were decreased following HGD. Furthermore, we observed an HGD-induced epithelioid and synthetic morphological appearance accompanied by disorganized cytoskeletal filaments, which was rescued by ozanimod. Thus, we conclude that ozanimod, a selective S1PR₁ ligand, protects against acute HGD-induced phenotypic switching and promotes cell survival, in part, by attenuating HGD-induced autophagic flux thus improving vascular patency in response to acute ischemia-like injury.

Soluble Epoxide Hydrolase in Aged Female Mice and Human Explanted Hearts Following Ischemic Injury

Myocardial infarction (MI) accounts for a significant proportion of death and morbidity in aged individuals. The risk for MI in females increases as they enter the peri-menopausal period, generally occurring in middle-age. Cytochrome (CYP) 450 metabolizes N-3 and N-6 polyunsaturated fatty acids (PUFA) into numerous lipid mediators, oxylipids, which are further metabolised by soluble epoxide hydrolase (sEH), reducing their activity. The objective of this study was to characterize oxylipid metabolism in the left ventricle (LV) following ischemic injury in females. Human LV specimens were procured from female patients with ischemic cardiomyopathy (ICM) or non-failing controls (NFC). Female C57BL6 (WT) and sEH null mice averaging 13–16 months old underwent permanent occlusion of the left anterior descending coronary artery (LAD) to induce myocardial infarction. WT (wild type) mice received vehicle or sEH inhibitor, trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid (tAUCB), in their drinking water ad libitum for 28 days. Cardiac function was assessed using echocardiography and electrocardiogram. Protein expression was determined using immunoblotting, mitochondrial activity by spectrophotometry, and cardiac fibre respiration was measured using a Clark-type electrode. A full metabolite profile was determined by LC–MS/MS. sEH was significantly elevated in ischemic LV specimens from patients, associated with fundamental changes in oxylipid metabolite formation and significant decreases in mitochondrial enzymatic function. In mice, pre-treatment with tAUCB or genetic deletion of sEH significantly improved survival, preserved cardiac function, and maintained mitochondrial quality following MI in female mice. These data indicate that sEH may be a relevant pharmacologic target for women with MI. Although future studies are needed to determine the mechanisms, in this pilot study we suggest targeting sEH may be an effective strategy for reducing ischemic injury and mortality in middle-aged females.

Microglia exosomal miRNA-137 attenuates ischemic brain injury through targeting Notch1

Microglia are the resident immune cells in the central nervous system and play an essential role in brain homeostasis and neuroprotection in brain diseases. Exosomes are crucial in intercellular communication by transporting bioactive miRNAs. Thus, this study aimed to investigate the function of microglial exosome in the presence of ischemic injury and related mechanism. Oxygen-glucose deprivation (OGD)-treated neurons and transient middle cerebral artery occlusion (TMCAO)-treated mice were applied in this study. Western blotting, RT-PCR, RNA-seq, luciferase reporter assay, transmission electron microscope, nanoparticle tracking analysis, immunohistochemistry, TUNEL and LDH assays, and behavioral assay were applied in mechanistic and functional studies. The results demonstrated that exosomes derived from microglia in M2 phenotype (BV2-Exo) were internalized by neurons and attenuated neuronal apoptosis in response to ischemic injury in vitro and in vivo. BV2-Exo also decreased infarct volume and behavioral deficits in ischemic mice. Exosomal miRNA-137 was upregulated in BV2-Exo and participated in the partial neuroprotective effect of BV2-Exo. Furthermore, Notch1 was a directly targeting gene of exosomal miRNA-137. In conclusion, these results suggest that BV2-Exo alleviates ischemia-reperfusion brain injury through transporting exosomal miRNA-137. This study provides novel insight into microglial exosomes-based therapies for the treatment of ischemic brain injury.

Cardioprotection via Metabolism for Rat Heart Preservation Using the High-Pressure Gaseous Mixture of Carbon Monoxide and Oxygen

The high-pressure gas (HPG) method with carbon monoxide (CO) and oxygen (O₂) mixture maintains the preserved rat heart function. The metabolites of rat hearts preserved using the HPG method (HPG group) and cold storage (CS) method (CS group) by immersion in a stock solution for 24 h were assessed to confirm CO and O₂ effects. Lactic acid was significantly lower and citric acid was significantly higher in the HPG group than in the CS group. Moreover, adenosine triphosphate (ATP) levels as well as some pentose phosphate pathway (PPP) metabolites and reduced nicotinamide adenine dinucleotide phosphate (NADPH) were significantly higher in the HPG group than in the CS group. Additionally, reduced glutathione (GSH), which protects cells from oxidative stress, was also significantly higher in the HPG group than in the CS group. These results indicated that each gas, CO and O₂, induced the shift from anaerobic to aerobic metabolism, maintaining the energy of ischemic preserved organs, shifting the glucose utilization from glycolysis toward PPP, and reducing oxidative stress. Both CO and O₂ in the HPG method have important effects on the ATP supply and decrease oxidative stress for preventing ischemic injury. The HPG method may be useful for clinical application.

Tat-Biliverdin Reductase A Exerts a Protective Role in Oxidative Stress-Induced Hippocampal Neuronal Cell Damage by Regulating the Apoptosis and MAPK Signaling

Reactive oxygen species (ROS) is major risk factor in neuronal diseases including ischemia. Although biliverdin reductase A (BLVRA) plays a pivotal role in cell survival via its antioxidant function, its role in hippocampal neuronal (HT-22) cells and animal ischemic injury is not clearly understood yet. In this study, the effects of transducible fusion protein Tat-BLVRA on H₂O₂-induced HT-22 cell death and in an animal ischemia model were investigated. Transduced Tat-BLVRA markedly inhibited cell death, DNA fragmentation, and generation of ROS. Transduced Tat-BLVRA inhibited the apoptosis and mitogen activated protein kinase (MAPK) signaling pathway and it passed through the blood-brain barrier (BBB) and significantly prevented hippocampal cell death in an ischemic model. These results suggest that Tat-BLVRA provides a possibility as a therapeutic molecule for ischemia.

Arginase Pathway in Acute Retina and Brain Injury: Therapeutic Opportunities and Unexplored Avenues

Ischemic retinopathies represent a major cause of visual impairment and blindness. They include diabetic retinopathy (DR), acute glaucoma, retinopathy of prematurity (ROP), and central (or branch) retinal artery occlusion (CRAO). These conditions share in common a period of ischemia or reduced blood supply to the retinal tissue that eventually leads to neuronal degeneration. Similarly, acute brain injury from ischemia or trauma leads to neurodegeneration and can have devastating consequences in patients with stroke or traumatic brain injury (TBI). In all of these conditions, current treatment strategies are limited by their lack of effectiveness, adverse effects or short time window for administration. Therefore, there is a great need to identify new therapies for acute central nervous system (CNS) injury. In this brief review article, we focus on the pathway of the arginase enzyme as a novel therapeutic target for acute CNS injury. We review the recent work on the role of arginase enzyme and its downstream components in neuroprotection in both retina and brain acute injury models. Delineating the similarities and differences between the role of arginase in the retina and brain neurodegeneration will allow for better understanding of the role of arginase in CNS disorders. This will also facilitate repurposing the arginase pathway as a new therapeutic target in both retina and brain diseases.

Kanglexin, a novel anthraquinone compound, protects against myocardial ischemic injury in mice by suppressing NLRP3 and pyroptosis

Pyroptosis is a form of inflammatory cell death that could be driven by the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation following myocardial infarction (MI). Emerging evidence suggests the therapeutic potential for ameliorating MI-induced myocardial damages by targeting NLRP3 and pyroptosis. In this study, we investigated the myocardial protection effect of a novel anthraquinone compound (4,5-dihydroxy-7-methyl-9,10-anthraquinone-2-ethyl succinate) named Kanglexin (KLX) in vivo and in vitro. Male C57BL/6 mice were pre-treated either with KLX (20, 40 mg· kg^-1per day, intragastric gavage) or vehicle for 7 consecutive days prior to ligation of coronary artery to induce permanent MI. KLX administration dose-dependently reduced myocardial infarct size and lactate dehydrogenase release and improved cardiac function as compared to vehicle-treated mice 24 h after MI. We found that MI triggered NLRP3 inflammasome activation leading to conversion of interleukin-1β (IL-1β) and IL-18 into their active mature forms in the heart, which could expand the infarct size and drive cardiac dysfunction. We also showed that MI induced pyroptosis, as evidenced by increased DNA fragmentation, mitochondrial swelling, and cell membrane rupture, as well as increased levels of pyroptosis-related proteins, including gasdermin D, N-terminal GSDMD, and cleaved caspase-1. All these detrimental alterations were prevented by KLX. In hypoxia- or lipopolysaccharide (LPS)-treated neonatal mouse ventricular cardiomyocytes, we showed that KLX (10 μM) decreased the elevated levels of terminal deoxynucleotidyl transferase dUTP nick end labeling- and propidium iodide-positive cells, and pyroptosis-related proteins. We conclude that KLX prevents MI-induced cardiac damages and cardiac dysfunction at least partly through attenuating NLRP3 and subsequent cardiomyocyte pyroptosis, and it is worthy of more rigorous investigations for its potential for alleviating ischemic heart disease.

Dendritic Cells as Sensors, Mediators, and Regulators of Ischemic Injury

Dendritic cells (DCs) are highly specialized, bone marrow (BM)-derived antigen-processing and -presenting cells crucial to the induction, integration and regulation of innate, and adaptive immunity. They are stimulated by damage-associated molecular patterns (DAMPS) via pattern recognition receptors to promote inflammation and initiate immune responses. In addition to residing within the parenchyma of all organs as part of the heterogeneous mononuclear phagocyte system, DCs are an abundant component of the inflammatory cell infiltrate that appears in response to ischemia reperfusion injury (IRI). They can play disparate roles in the pathogenesis of IRI since their selective depletion has been found to be protective, deleterious, or of no benefit in mouse models of IRI. In addition, administration of DC generated and manipulated ex vivo can protect organs from IRI by suppressing inflammatory cytokine production, limiting the capacity of DCs to activate NKT cells, or enhancing regulatory T cell function. Few studies however have investigated specific signal transduction mechanisms underlying DC function and how these affect IRI. Here, we address current knowledge of the role of DCs in regulation of IRI, current gaps in understanding and prospects for innovative therapeutic intervention at the biological and pharmacological levels.

A Histological and Clinical Evaluation of Plasma as a Graft Holding Solution and Its Efficacy in Terms of Hair Growth and Graft Survival

Background  There is a time lag between hair follicle harvesting and implantation, during this time hair follicles suffer ischemic injury. We need a holding medium or a solution to minimize or neutralize ischemic injury.

Aims and Objective  To evaluate plasma as a graft holding solution in terms of its efficacy in hair growth and hair graft survival.

Method and Material  A split scalp study was performed. The left side was designated as the control area (Group A) where grafts implanted were kept in Ringer’s lactate, and the right side behaved as the test area (Group B) and received grafts preserved in autologous plasma. The p -value was calculated.

Observations  MTT staining for grafts stored in Ringer’s lactate at 12 and 72 hours showed poor hair follicle cells’ survival while grafts kept in plasma showed viable cells even after 72 hours.

The hair count and density in plasma group were significantly higher than those in the Ringer’s lactate group. There was an improvement in hair thickness in both groups from 6 months to 12 months.

Conclusion  Autologous plasma is an easily available graft holding solution. Platelets along with the plasma provide multiple growth factors promoting epithelialization, neovascularization, and action on hair follicle stem cells to improve growth. The fibrin coating around the graft makes it sticky and prevents dehydration. The split scalp controlled study certainly shows the advantages of using plasma over other extra cellular graft holding solutions.

A NeuroD1 AAV-Based Gene Therapy for Functional Brain Repair after Ischemic Injury through In Vivo Astrocyte-to-Neuron Conversion

Adult mammalian brains have largely lost neuroregeneration capability except for a few niches. Previous studies have converted glial cells into neurons, but the total number of neurons generated is limited and the therapeutic potential is unclear. Here, we demonstrate that NeuroD1-mediated in situ astrocyte-to-neuron conversion can regenerate a large number of functional new neurons after ischemic injury. Specifically, using NeuroD1 adeno-associated virus (AAV)-based gene therapy, we were able to regenerate one third of the total lost neurons caused by ischemic injury and simultaneously protect another one third of injured neurons, leading to a significant neuronal recovery. RNA sequencing and immunostaining confirmed neuronal recovery after cell conversion at both the mRNA level and protein level. Brain slice recordings found that the astrocyte-converted neurons showed robust action potentials and synaptic responses at 2 months after NeuroD1 expression. Anterograde and retrograde tracing revealed long-range axonal projections from astrocyte-converted neurons to their target regions in a time-dependent manner. Behavioral analyses showed a significant improvement of both motor and cognitive functions after cell conversion. Together, these results demonstrate that in vivo cell conversion technology through NeuroD1-based gene therapy can regenerate a large number of functional new neurons to restore lost neuronal functions after injury.

Nicotinamide phosphoribosyltransferase secreted from microglia via exosome during ischemic injury

Nicotinamide phosphoribosyltransferase (NAMPT) is the key enzyme of the salvage pathway of nicotinamide adenine dinucleotide synthesis. NAMPT can also be secreted and functions as a cytokine. We have previously shown that in the brain, NAMPT expression and secretion can be induced in microglia upon neuroinflammation and injury. Yet the mechanism for NAMPT secretion remains unclear. Here we show that NAMPT can be actively secreted from microglia upon the treatment of ischemia-like injury - oxygen-glucose deprivation and recovery (OGD/R). We confirmed that classical ER-Golgi pathway is not involved in NAMPT secretion. NAMPT secretion was further enhanced by ATP, and the secretion was mediated by P2X₇ receptor and by intracellular Ca²⁺ . Importantly, we found that phospholipase D inhibitor, n-butanol, phospholipase D siRNA, and wortmannin significantly decreased OGD/R-induced and ATP-enhanced release of NAMPT in microglia. After excluding the mechanisms of involving secretory autophagy, endosomes, and secretory lysosome, we have concluded that microglial NAMPT is secreted mainly via exosome. Immune-electron microscopy identifies NAMPT in extracellular vesicles with the size and morphology characteristic of exosome. With the vesicles harvested by ultra-centrifugation, exosomal NAMPT is further confirmed by Western blotting analysis. Intriguingly, the amount of NAMPT relative to exosomal protein markers remains unchanged upon the treatment of OGD/R, suggesting a constant load of exosomal NAMPT in microglia. Taken together, we have identified NAMPT is actively secreted via exosome from microglia during neuroinflammation of ischemic injury.

β-Arrestin-2-ERK1/2 cPLA2α axis mediates TLR4 signaling to influence eicosanoid induction in ischemic brain

LPS has been shown to elicit neuroinflammation associated with the up-regulation of the eicosanoid pathway in animal models; however, the regulatory mechanisms of TLR4 in brain neuroinflammatory conditions remain elusive. β-Arrestins are key regulators of the GPCR signaling pathway and are involved in the leukotriene B4-induced leukocyte migration to initiate inflammatory response. However, the roles of β-arrestins in eicosanoid regulation and related diseases are not clear. To address this issue, we conducted a study to investigate the effect of TLR4 on the eicosanoid pathway in ischemic stroke brain and to explore the underlying molecular regulation mechanism. Cerebral ischemia was produced by occlusion of the middle cerebral artery, followed by reperfusion for 24 h. We demonstrated that knockout of TLR4 improves ischemic stroke brain associated with eicosanoid down-regulation. Interestingly, genetic disruption of β-arrestin-2 failed to decrease neuroinflammation in the damaged brain of TLR4^-/- mice, which indicates the requirement of β-arrestin-2 for TLR4 knockdown protection. Further study showed that the negative regulation of phosphorylated (phospho-)ERK1/2 and phospho-cytosolic phospholipase A₂ α (cPLA₂α) by TLR4 deficiency was eliminated by genetic disruption of β-arrestin-2. In addition, β-arrestin-2 deficiency reversed the reduction of colocalization of phospho-ERK1/2 with phospho-cPLA₂α in TLR4^-/- mice following ischemic stroke. Mechanistic studies indicated that β-arrestin-2 specifically colocalized and associated with ERK1/2 to prevent ERK1/2-dependent cPLA₂α activation following ischemic injury, and β-arrestin-2 deficiency blocked the negative regulation of phospho-ERK1/2, revived the association of phospho-ERK1/2 with phospho-cPLA₂α, and subsequently increased the prostaglandin E2 and thromboxane A2 production remarkably. Our findings may provide novel insights that β-arrestin-2 is responsible for ischemic brain improvement in TLR4^-/- mice via negative regulation of eicosanoid production.-Xiang, Y., Wei, X., Du, P., Zhao, H., Liu, A., Chen, Y. β-Arrestin-2-ERK1/2 cPLA₂α axis mediates TLR4 signaling to influence eicosanoid induction in ischemic brain.

Platelet-Inspired Nanocells for Targeted Heart Repair After Ischemia/Reperfusion Injury

Cardiovascular disease is the leading cause of mortality worldwide. While reperfusion therapy is vital for patient survival post-heart attack, it also causes further tissue injury, known as myocardial ischemia/reperfusion (I/R) injury in clinical practice. Exploring ways to attenuate I/R injury is of clinical interest for improving post-ischemic recovery. A platelet-inspired nanocell (PINC) that incorporates both prostaglandin E2 (PGE2)-modified platelet membrane and cardiac stromal cell-secreted factors to target the heart after I/R injury is introduced. By taking advantage of the natural infarct-homing ability of platelet membrane and the overexpression of PGE2 receptors (EPs) in the pathological cardiac microenvironment after I/R injury, the PINCs can achieve targeted delivery of therapeutic payload to the injured heart. Furthermore, a synergistic treatment efficacy can be achieved by PINC, which combines the paracrine mechanism of cell therapy with the PGE2/EP receptor signaling that is involved in the repair and regeneration of multiple tissues. In a mouse model of myocardial I/R injury, intravenous injection of PINCs results in augmented cardiac function and mitigated heart remodeling, which is accompanied by the increase in cycling cardiomyocytes, activation of endogenous stem/progenitor cells, and promotion of angiogenesis. This approach represents a promising therapeutic delivery platform for treating I/R injury.

A Histological and Clinical Evaluation of Plasma as a Graft-holding Solution and Its Efficacy in Terms of Hair Growth and Graft Survival

Background

There is a time lag between hair follicle harvesting and implantation; during this time, hair follicles have ischemic injury. We need a holding media or a solution to minimize or neutralize ischemic injury.

Aim and Objectives

The aim of this study was to evaluate plasma as a graft-holding solution in terms of its efficacy in hair growth and hair graft survival.

Materials and Methods

A split-scalp study was carried out. The left side was designated as the control area (Group A), where graft implanted was kept in Ringer's lactate (RL), and the right side behaved as the test area (Group B), which received grafts preserved in autologous plasma. The P value was calculated.

Observations

MTT [3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide] staining for graft stored in RL at 12-72h showed poor hair follicles cells survival, whereas graft kept in plasma showed viable cells even after 72h. The hair count and density in plasma group were significantly higher than the RL group. There was an improvement in hair thickness in both groups from 6 to 12 months.

Conclusion

Autologous plasma is an easily available graft-holding solution. Platelets along with the plasma provide multiple growth factors promoting epithelialization, neovascularization, and action on hair follicle stem cells to improve growth. The fibrin coating around graft makes it sticky and prevents dehydration. The split-scalp controlled study certainly shows the advantages of using plasma over other extracellular graft-holding solutions.

The myeloid mineralocorticoid receptor controls inflammatory and fibrotic responses after renal injury via macrophage interleukin-4 receptor signaling

Acute kidney injury induced by ischemia/reperfusion is an independent risk factor for chronic kidney disease. Macrophage recruitment plays an essential role during the injury and repair phases after an ischemic episode in the kidney. Here we show that the novel non-steroidal mineralocorticoid receptor antagonist finerenone or selective myeloid mineralocorticoid receptor ablation protects against subsequent chronic dysfunction and fibrosis induced by an episode of bilateral kidney ischemia/reperfusion in mice. This protection was associated with increased expression of M2-antiinflamatory markers in macrophages from finerenone-treated or myeloid mineralocorticoid receptor-deficient mice. Moreover, the inflammatory population of CD11b⁺, F4/80⁺, Ly6C^high macrophages was also reduced. Mineralocorticoid receptor inhibition promoted increased IL-4 receptor expression and activation in the whole kidney and in isolated macrophages, thereby facilitating macrophage polarization to an M2 phenotype. The long-term protection conferred by mineralocorticoid receptor antagonism was also translated to the Large White pig pre-clinical model. Thus, our studies support the rationale for using mineralocorticoid receptor antagonists in clinical practice to prevent transition of acute kidney injury to chronic kidney disease.

Upregulation of miR-216a exerts neuroprotective effects against ischemic injury through negatively regulating JAK2/STAT3-involved apoptosis and inflammatory pathways

OBJECTIVE

Ischemic stroke remains a significant cause of death and disability in industrialized nations. Janus tyrosine kinase (JAK) and signal transducer and activator of transcription (STAT) of the JAK2/STAT3 pathway play important roles in the downstream signal pathway regulation of ischemic stroke-related inflammatory neuronal damage. Recently, microRNAs (miRNAs) have emerged as major regulators in cerebral ischemic injury; therefore, the authors aimed to investigate the underlying molecular mechanism between miRNAs and ischemic stroke, which may provide potential therapeutic targets for ischemic stroke.

METHODS

The JAK2- and JAK3-related miRNA (miR-135, miR-216a, and miR-433) expression levels were detected by real-time quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) and Western blot analysis in both oxygen-glucose deprivation (OGD)-treated primary cultured neuronal cells and mouse brain with middle cerebral artery occlusion (MCAO)-induced ischemic stroke. The miR-135, miR-216a, and miR-433 were determined by bioinformatics analysis that may target JAK2, and miR-216a was further confirmed by 3' untranslated region (3'UTR) dual-luciferase assay. The study further detected cell apoptosis, the level of lactate dehydrogenase, and inflammatory mediators (inducible nitric oxide synthase [iNOS], matrix metalloproteinase-9 [MMP-9], tumor necrosis factor-α [TNF-α], and interleukin-1β [IL-1β]) after cells were transfected with miR-NC (miRNA negative control) or miR-216a mimics and subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) damage with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, annexin V-FITC/PI, Western blots, and enzyme-linked immunosorbent assay detection. Furthermore, neurological deficit detection and neurological behavior grading were performed to determine the infarction area and neurological deficits.

RESULTS

JAK2 showed its highest level while miR-216a showed its lowest level at day 1 after ischemic reperfusion. However, miR-135 and miR-433 had no obvious change during the process. The luciferase assay data further confirmed that miR-216a can directly target the 3'UTR of JAK2, and overexpression of miR-216a repressed JAK2 protein levels in OGD/R-treated neuronal cells as well as in the MCAO model ischemic region. In addition, overexpression of miR-216a mitigated cell apoptosis both in vitro and in vivo, which was consistent with the effect of knockdown of JAK2. Furthermore, the study found that miR-216a obviously inhibited the inflammatory mediators after OGD/R, including inflammatory enzymes (iNOS and MMP-9) and cytokines (TNF-α and IL-1β). Upregulating miR-216a levels reduced ischemic infarction and improved neurological deficit.

CONCLUSIONS

These findings suggest that upregulation of miR-216a, which targets JAK2, could induce neuroprotection against ischemic injury in vitro and in vivo, which provides a potential therapeutic target for ischemic stroke.

MicroRNA-365 modulates astrocyte conversion into neuron in adult rat brain after stroke by targeting Pax6

Reactive astrocytes induced by ischemia can transdifferentiate into mature neurons. This neurogenic potential of astrocytes may have therapeutic value for brain injury. Epigenetic modifications are widely known to involve in developmental and adult neurogenesis. PAX6, a neurogenic fate determinant, contributes to the astrocyte‐to‐neuron conversion. However, it is unclear whether microRNAs (miRs) modulate PAX6‐mediated astrocyte‐to‐neuron conversion. In the present study we used bioinformatic approaches to predict miRs potentially targeting Pax6, and transient middle cerebral artery occlusion (MCAO) to model cerebral ischemic injury in adult rats. These rats were given striatal injection of glial fibrillary acidic protein targeted enhanced green fluorescence protein lentiviral vectors (Lv‐GFAP‐EGFP) to permit cell fate mapping for tracing astrocytes‐derived neurons. We verified that miR‐365 directly targets to the 3′‐UTR of Pax6 by luciferase assay. We found that miR‐365 expression was significantly increased in the ischemic brain. Intraventricular injection of miR‐365 antagomir effectively increased astrocytic PAX6 expression and the number of new mature neurons derived from astrocytes in the ischemic striatum, and reduced neurological deficits as well as cerebral infarct volume. Conversely, miR‐365 agomir reduced PAX6 expression and neurogenesis, and worsened brain injury. Moreover, exogenous overexpression of PAX6 enhanced the astrocyte‐to‐neuron conversion and abolished the effects of miR‐365. Our results demonstrate that increase of miR‐365 in the ischemic brain inhibits astrocyte‐to‐neuron conversion by targeting Pax6, whereas knockdown of miR‐365 enhances PAX6‐mediated neurogenesis from astrocytes and attenuates neuronal injury in the brain after ischemic stroke. Our findings provide a foundation for developing novel therapeutic strategies for brain injury.

Suxiao Jiuxin Pill protects cardiomyocytes against mitochondrial injury and alters gene expression during ischemic injury

Suxiao Jiuxin Pill (SX), a traditional Chinese medicine compound consisting primarily of tetramethylpyrazine and borneol, has been reported to protect against ischemic heart disease. However, the effects of SX on mitochondrial injury and gene expression in various signaling pathways are unclear. The aim of the present study was to investigate the effects of SX on mitochondrial injury and to screen the expression of genes potentially altered by SX using a cell culture model of ischemic injury. Simulated ischemia was established by culturing HL-1 cardiomyocytes in Dulbecco's modified Eagle medium without glucose or serum in a hypoxic chamber containing 95% N₂ and 5% CO₂ for 24 h. HL-1 cardiomyocytes were divided into 3 groups: Control, ischemic injury and ischemic injury + SX (100 µg/ml; n=3 wells/group). Mitochondrial membrane potential was detected by staining with JC-1 dye. The mRNA expression levels of adenylyl cyclase (Adcy) 1–9, adrenoceptor β1, Akt1, ATPase Na+/K+ transporting subunit β2, calcium voltage-gated channel auxiliary subunit α2δ (Cacna2d)2, Cacna2d3, calcium channel voltage-dependent γ subunit 8, cytochrome C oxidase subunit 6A2 (Cox6a2), fibroblast growth factor receptor (Fgfr) 4, Fgf8, Fgf12, Gnas complex locus, glycogen synthase kinase 3β (Gsk3b), mitogen-activated protein kinase (Mapk)11-14, Mapk kinase kinase kinase 1 (Map4k1), Mas1, nitric oxide synthase 3 (Nos3), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit α (Pik3ca), phospholipase A2 group 4A, rap guanine nucleotide exchange factor 4 and ryanodine receptor 2 were detected using reverse transcription-quantitative polymerase chain reaction. The protein expression levels of phosphoinositide 3-kinase (PI3K), MAS-1 and phosphorylated-endothelial NOS were also examined by immunofluorescence staining. The decrease in mitochondrial membrane potential in the cell culture model of ischemic injury (P<0.001) was significantly attenuated by SX treatment (P<0.001). Furthermore, increases in the mRNA expression levels of Adcy2 (P<0.05), 3 (P<0.01) and 8 (P<0.05) in the ischemic injury model were significantly attenuated by SX treatment (P<0.01), and SX treatment significantly decreased the mRNA expression levels of Adcy1 (P<0.01) and 6 (P<0.05) in ischemic cells. Decreases in the mRNA expression levels of Cox6a2 (P<0.001), Gsk3b (P<0.01) and Pik3ca (P<0.001) in the ischemic injury model were also significantly attenuated by SX treatment (P<0.05, P<0.01 and P<0.001, respectively). In addition, the decrease in the protein expression of PI3K (P<0.001) was significantly attenuated by SX treatment (P<0.001). The present findings indicate that SX may protect cardiomyocytes against mitochondrial injury and attenuate alterations in the gene expression of Adcy2, 3 and 8, Cox6a2, Gsk3b and Pik3ca during ischemic injury.

Hypoxic Preconditioning Promotes the Bioactivities of Mesenchymal Stem Cells via the HIF-1α-GRP78-Akt Axis

Mesenchymal stem cells (MSC) are ideal materials for stem cell-based therapy. As MSCs reside in hypoxic microenvironments (low oxygen tension of 1% to 7%), several studies have focused on the beneficial effects of hypoxic preconditioning on MSC survival; however, the mechanisms underlying such effects remain unclear. This study aimed to uncover the potential mechanism involving 78-kDa glucose-regulated protein (GRP78) to explain the enhanced MSC bioactivity and survival in hindlimb ischemia. Under hypoxia (2% O₂), the expression of GRP78 was significantly increased via hypoxia-inducible factor (HIF)-1α. Hypoxia-induced GRP78 promoted the proliferation and migration potential of MSCs through the HIF-1α-GRP78-Akt signal axis. In a murine hind-limb ischemia model, hypoxic preconditioning enhanced the survival and proliferation of transplanted MSCs through suppression of the cell death signal pathway and augmentation of angiogenic cytokine secretion. These effects were regulated by GRP78. Our findings indicate that hypoxic preconditioning promotes survival, proliferation, and angiogenic cytokine secretion of MSCs via the HIF-1α-GRP78-Akt signal pathway, suggesting that hypoxia-preconditioned MSCs might provide a therapeutic strategy for MSC-based therapies and that GRP78 represents a potential target for the development of functional MSCs.

Wild-type p53-induced Phosphatase 1 Deficiency Exacerbates Myocardial Infarction-induced Ischemic Injury

BACKGROUND

Myocardial infarction (MI) is a major disease burden. Wild-type p53-induced phosphatase 1 (Wip1) has been studied extensively in the context of cancer and the regulation of different types of stem cells, but the role of Wip1 in cardiac adaptation to MI is unknown. We investigated the significance of Wip1 in a mouse model of MI.

METHODS

The study began in June 2014 and was completed in July 2016. We compared Wip1-knockout (Wip1-KO) mice and wild-type (WT) mice to determine changes in cardiac function and survival in response to MI. The heart weight/body weight (HW/BW) ratio and cardiac function were measured before MI. Mouse MI was established by ligating the left anterior descending (LAD) coronary artery under 1.5% isoflurane anesthesia. After MI, survival of the mice was observed for 4 weeks. Cardiac function was examined by echocardiography. The HW/BW ratio was analyzed, and cardiac hypertrophy was measured by wheat germ agglutinin staining. Hematoxylin and eosin (H&E) staining was used to determine the infarct size. Gene expression of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) was assessed by quantitative real-time polymerase chain reaction (qPCR), and the levels of signal transducers and activators of transcription 3 (stat3) and phosphor-stat3 (p-stat3) were also analyzed by Western blotting. Kaplan-Meier survival analysis, log-rank test, unpaired t-test, and one-way analysis of variance (ANOVA) were used for statistical analyses.

RESULTS

Wip1-KO mice had a marginally increased HW/BW ratio and slightly impaired cardiac function before LAD ligation. After MI, Wip1-deficient mice exhibited increased mortality (57.14% vs. 29.17%; n = 24 [WT], n = 35 [Wip1-KO], P< 0.05), increased cardiac hypertrophy (HW/BW ratio: 7 days: 7.25 ± 0.36 vs. 5.84 ± 0.18, n = 10, P< 0.01, and 4 weeks: 6.05 ± 0.17 vs. 5.87 ± 0.24, n = 10, P > 0.05; cross-sectional area: 7 days: 311.80 ± 8.29 vs. 268.90 ± 11.15, n = 6, P< 0.05, and 4 weeks: 308.80 ± 11.26 vs. 317.00 ± 13.55, n = 6, P > 0.05), and reduced cardiac function (ejection fraction: 7 days: 29.37 ± 1.38 vs. 34.72 ± 1.81, P< 0.05, and 4 weeks: 19.06 ± 2.07 vs. 26.37 ± 2.95, P< 0.05; fractional shortening: 7 days: 13.72 ± 0.71 vs. 16.50 ± 0.94, P< 0.05, and 4 weeks: 8.79 ± 1.00 vs. 12.48 ± 1.48, P< 0.05; n = 10 [WT], n = 15 [Wip1-KO]). H&E staining revealed a larger infarct size in Wip1-KO mice than in WT mice (34.79% ± 2.44% vs. 19.55% ± 1.48%, n = 6, P< 0.01). The expression of IL-6 and p-stat3 was downregulated in Wip1-KO mice (IL-6: 1.71 ± 0.27 vs. 4.46 ± 0.79, n = 6, P< 0.01; and p-stat3/stat3: 1.15 ± 0.15 vs. 1.97 ± 0.23, n = 6, P< 0.05).

CONCLUSION

The results suggest that Wip1 could protect the heart from MI-induced ischemic injury.

Quantitative photoacoustic imaging for early detection of muscle ischemia injury

Acute lower extremity ischemia is a limb-and life-threatening problem. The timing of clinical intervention is critical to achieving optimal outcomes. However, there has been a lack of effective techniques capable of evaluating muscle and limb damage. Microcirculatory injury is the initial pathological change during ischemic muscle injury. Here, we performed photoacoustic imaging (PAI) in real time to quantitatively detect the degree of microcirculatory injury of ischemic muscles in a rat model in which Evans blue (EB), which strongly binds to albumin in blood, was used as a nontoxic molecular PA probe. The right lower hind limbs of Sprague-Dawley (SD) rats were subjected to 2 or 3 hours of tourniquet-induced ischemia. Then, PA imaging of the tibialis anterior (TA) muscles in the anterior compartment was performed for 0-24 h after the release of compression. Twenty-four hours after reperfusion, rats were euthanized and examined for pathology, edema and muscle viability. Imaging at 680 nm on rats revealed that there was significant signal enhancement in the TA muscles of the two injury groups compared to the control group, and the 3-h injury group had significantly higher PA signal intensity than the 2-h injury group at each time point. Histopathology results obtained from both the normal and the damaged muscles correlated well with the PAI findings. In conclusion, PA imaging is a promising modality for quantitatively detecting limb and muscle ischemic injury and may pave the road for further clinical application.

Therapeutic potential of adipose-derived stem cells and macrophages for ischemic skeletal muscle repair

AIM

Progressive ischemia due to peripheral artery disease causes muscle damage and reduced strength of the lower extremities. Autologous cell therapy is an attractive treatment to restore perfusion and improve muscle function. Adipose-derived stem cells (ASCs) have therapeutic potential in tissue repair, including polarizing effects on macrophages (MPs).

MATERIALS & METHODS

Co-culture systems of ASCs and MPs were analyzed for gene and protein expression modifications in ASC-conditioned MPs. Co-transplantation of MPs/ASCs in vivo led to improved skeletal muscle regeneration in a mouse model of peripheral artery disease.

RESULTS

ASCs/MPs therapy restored muscle function, increased perfusion and reduced inflammatory infiltrate.

CONCLUSION

Combined MPs/ASCs cell therapy is a promising approach to restore muscle function and stimulate local angiogenesis in the ischemic limb.

Identification of Proteins Interacting with Cytoplasmic High-Mobility Group Box 1 during the Hepatocellular Response to Ischemia Reperfusion Injury

Ischemia/reperfusion injury (IRI) occurs inevitably in liver transplantations and frequently during major resections, and can lead to liver dysfunction as well as systemic disorders. High-mobility group box 1 (HMGB1) plays a pathogenic role in hepatic IRI. In the normal liver, HMGB1 is located in the nucleus of hepatocytes; after ischemia reperfusion, it translocates to the cytoplasm and it is further released to the extracellular space. Unlike the well-explored functions of nuclear and extracellular HMGB1, the role of cytoplasmic HMGB1 in hepatic IRI remains elusive. We hypothesized that cytoplasmic HMGB1 interacts with binding proteins involved in the hepatocellular response to IRI. In this study, binding proteins of cytoplasmic HMGB1 during hepatic IRI were identified. Liver tissues from rats with warm ischemia reperfusion (WI/R) injury and from normal rats were subjected to cytoplasmic protein extraction. Co-immunoprecipitation using these protein extracts was performed to enrich HMGB1-protein complexes. To separate and identify the immunoprecipitated proteins in eluates, 2-dimensional electrophoresis and subsequent mass spectrometry detection were performed. Two of the identified proteins were verified using Western blotting: betaine–homocysteine S-methyltransferase 1 (BHMT) and cystathionine γ-lyase (CTH). Therefore, our results revealed the binding of HMGB1 to BHMT and CTH in cytoplasm during hepatic WI/R. This finding may help to better understand the cellular response to IRI in the liver and to identify novel molecular targets for reducing ischemic injury.

Cardiac Arrest-Induced Global Brain Hypoxia-Ischemia during Development Affects Spontaneous Activity Organization in Rat Sensory and Motor Thalamocortical Circuits during Adulthood

Normal maturation of sensory information processing in the cortex requires patterned synaptic activity during developmentally regulated critical periods. During early development, spontaneous synaptic activity establishes required patterns of synaptic input, and during later development it influences patterns of sensory experience-dependent neuronal firing. Thalamocortical neurons occupy a critical position in regulating the flow of patterned sensory information from the periphery to the cortex. Abnormal thalamocortical inputs may permanently affect the organization and function of cortical neuronal circuits, especially if they occur during a critical developmental window. We examined the effect of cardiac arrest (CA)-associated global brain hypoxia-ischemia in developing rats on spontaneous and evoked firing of somatosensory thalamocortical neurons and on large-scale correlations in the motor thalamocortical circuit. The mean spontaneous and sensory-evoked firing rate activity and variability were higher in CA injured rats. Furthermore, spontaneous and sensory-evoked activity and variability were correlated in uninjured rats, but not correlated in neurons from CA rats. Abnormal activity patterns of ventroposterior medial nucleus (VPm) neurons persisted into adulthood. Additionally, we found that neurons in the entopeduncular nucleus (EPN) in the basal ganglia had lower firing rates yet had higher variability and higher levels of burst firing after injury. Correlated levels of power in local field potentials (LFPs) between the EPN and the motor cortex (MCx) were also disrupted by injury. Our findings indicate that hypoxic-ischemic injury during development leads to abnormal spontaneous and sensory stimulus-evoked input patterns from thalamus to cortex. Abnormal thalamic inputs likely permanently and detrimentally affect the organization of cortical circuitry and processing of sensory information. Hypoxic-ischemic injury also leads to abnormal single neuron and population level activity in the basal ganglia that may contribute to motor dysfunction after injury. Combination of deficits in sensory and motor thalamocortical circuit function may negatively impact sensorimotor integration in CA survivors. Modulation of abnormal activity patterns post-injury may represent a novel therapeutic target to improve neurologic function in survivors.

Ovarian injury during cryopreservation and transplantation in mice: a comparative study between cryoinjury and ischemic injury

STUDY QUESTION

What is the main cause of ovarian injury during cryopreservation and transplantation in mice: cryoinjury or ischemic injury?

SUMMARY ANSWER

Post-transplantation ischemia is the main cause of ovarian injury during cryopreservation and transplantation for restoring ovarian function.

WHAT IS KNOWN ALREADY

During cryopreservation and the transplantation of ovaries, cryoinjury and ischemic injury inevitably occur, which has a detrimental effect on ovarian quality and reserve.

STUDY DESIGN, SIZE, DURATION

A total of 80 B6D2F1 female mice were randomly allocated to 2 control and 6 experimental groups according to the presence or the absence of transplantation (n = 10/group). The control groups consisted of fresh or vitrified-warmed controls that had the whole ovary fixed without transplantation (fresh and vitri-con, respectively). The experimental groups were further divided according to the presence of vitrification (fresh or vitrified-warmed) and the transplantation period (2 [D2], 7 [D7] or 21 [D21] days).

PARTICIPANTS/MATERIALS, SETTING, METHODS

In the control groups, fresh and vitrified-warmed ovaries were immediately fixed after the collection (fresh) and the vitrification-warming process (vitrification control, vitri-con), respectively. Of those experimental groups, three were auto-transplanted with fresh whole ovary (FrOT; FrOT-D2, FrOT-D7 and FrOT-D21). For the other three groups, the ovaries were harvested and stored in liquid nitrogen for 1 week after vitrification and then warmed to auto-transplant the vitrified whole ovaries (vitrified ovary [VtOT]; VtOT-D2, VtOT-D7 and VtOT-D21). After 2, 7 or 21 days of grafting, the grafts and blood sera were collected for analysis by hematoxylin-eosin staining, terminal deoxynucleotidyl transferase dUTP nick end labeling assay, CD31 immunohistochemistry and follicle-stimulating hormone enzyme-linked immunosorbent assay.

MAIN RESULTS AND THE ROLE OF CHANCE

The vitrification-warming procedure decreased the proportion of intact follicles (Grade 1, G1) (vitri-con 50.3% versus fresh 64.2%) but there was a larger decrease due to ischemic injury after transplantation (FrOT-D2: 42.5%). The percentage of apoptotic follicles was significantly increased in the vitrified-warmed ovary group compared with the fresh control, but it increased more after transplantation without vitrification (fresh: 0.9%, vitri-con: 6.0% and FrOT-D2: 26.8%). The mean number of follicles per section and percentage of CD31-positive area significantly decreased after vitrification but decreased to a larger extent after transplantation (number of follicles, fresh: 30.3 ± 3.6, vitri-con: 20.6 ± 2.9, FrOT-D2: 17.9 ± 2.1; CD31-positive area, fresh: 10.6 ± 1.3%, vitri-con: 5.7 ± 0.9% and FrOT-D2: 4.2 ± 0.4%). Regarding the G1 follicle ratio and CD31-positive area per graft, only the FrOT groups significantly recovered with time after transplantation (G1 follicle ratio, FrOT-D2: 42.5%, FrOT-D7: 56.1% and FrOT-D21: 70.7%; CD31-positive area, FrOT-D2: 4.2 ± 0.4%, FrOT-D7: 5.4 ± 0.6% and FrOT-D21: 7.5 ± 0.8%). Although there was no significant difference between the two transplantation groups at each evaluation, the serum follicle-stimulating hormone level of both groups significantly decreased over time.

LIMITATIONS AND REASONS FOR CAUTION

It is unclear how far these results can be extrapolated from mice to the human ovary.

WIDER IMPLICATIONS OF THE FINDINGS

Minimizing ischemic injury should be the first priority rather than preventing cryoinjury alone, and decreasing the combination of cryoinjury and ischemic injury is necessary to improve ovarian quality after cryopreservation and transplantation.

STUDY FUNDING/COMPETING INTEREST

This study was supported by a grant of the Korea Healthcare Technology R&D Project, Ministry of Health & Welfare, Republic of Korea (HI12C0055). The authors have no conflict of interest to declare.

Exposure to electromagnetic field attenuates oxygen-glucose deprivation-induced microglial cell death by reducing intracellular Ca(2+) and ROS

Purpose The aim of this research was to demonstrate the protective effects of electromagnetic field (EMF) exposure on the human microglial cell line, HMO6, against ischemic cell death induced by in vitro oxygen-glucose deprivation (OGD). Materials and methods HMO6 cells were cultured for 4 h under OGD with or without exposure to EMF with different combinations of frequencies and intensities (10, 50, or 100 Hz/1 mT and 50 Hz/0.01, 0.1, or 1 mT). Cell survival, intracellular calcium and reactive oxygen species (ROS) levels were measured. Results OGD caused significant HMO6 cell death as well as elevation of intracellular Ca(2+) and ROS levels. Among different combinations of EMF frequencies and intensities, 50 Hz/1 mT EMF was the most potent to attenuate OGD-induced cell death and intracellular Ca(2+) and ROS levels. A significant but less potent protective effect was also found at 10 Hz/1 mT, whereas no protective effect was found at other combinations of EMF. A xanthine oxidase inhibitor reversed OGD-induced ROS production and cell death, while NADPH oxidase and mitochondrial respiration chain complex II inhibitors did not affect cell death. Conclusions 50 Hz/1 mT EMF protects human microglial cells from OGD-induced cell death by interfering with OGD-induced elevation of intracellular Ca(2+) and ROS levels, and xanthine oxidase is one of the main mediators involved in OGD-induced HMO6 cell death. Non-invasive treatment of EMF radiation may be clinically useful to attenuate hypoxic-ischemic brain injury.