Model Of Focal Cerebral Ischemia Research Articles

Plasma metabonomic study on the effect of Para‑hydroxybenzaldehyde intervention in a rat model of transient focal cerebral ischemia.

Gastrodiaelata Blume has been widely used to treat various central and peripheral nerve diseases, and Para‑hydroxybenzaldehyde (PHBA) is one of the indicated components suggested to provide a neuroprotective effect. In our previous, it was shown that PHBA protected mitochondria against cerebral ischemia‑reperfusion (I/R) injury in rats. In the present study, how PHBA regulated the metabolic mechanism in blood following cerebral I/R was assessed to identify an effective therapeutic target for the prevention and treatment of ischemic stroke (IS). First, a rat model of cerebral ischemia‑reperfusion injury was established via middle cerebral artery occlusion/reperfusion (MCAO/R). The therapeutic effect of PHBA on brain I/R was evaluated by assessing the neurological function score, triphenyl tetrazolium chloride, hematoxylin and eosin, and Nissl staining. Next, a non‑targeted metabolomic based on high‑performance liquid chromatography quadrupole time‑of‑flight mass spectrometry was established to identify differential metabolites. Finally, a targeted metabolic spectrum was analyzed and the potential therapeutic targets were verified by Western blotting. The results showed that the neurological function score, cerebral infarction area, hippocampal morphology, and the number of neurons in the PHBA group were significantly improved compared with the model group. Metabonomic analysis showed that 13 different metabolites were identified between the model and PHBA group, which may be involved in the 'tricarboxylic acid cycle', 'glutathione metabolism', and 'mutual transformation of pentose and glucuronates', amongst others. Among these, the levels of the most significant differential metabolite, dGMP, decreased significantly following PHBA treatment. Western blotting was used to verify the expression of membrane‑associated guanosine kinase PSD‑95 and the subunit of glutamate AMPA receptor GluA1, which significantly increased after PHBA treatment. In addition, it was also found that PHBA increased the expression of the light chain‑3 protein and autophagy effector protein 1, whilst the expression of sequestosome‑1 decreased, indicating that PHBA promoted autophagy. Similarly, in TUNEL staining and detection of apoptosis‑related proteins, it was found that MCAO/R upregulated the expression of Bax and cleaved‑caspase‑3 whilst downregulating the expression of Bcl‑2 and increasing the apoptosis of hippocampal neurons; PHBA reversed this situation. These results suggest that cerebral I/R causes postsynaptic dysfunction by disrupting the interaction between PSD‑95 and AMPARs, and the inhibition of the autophagy system eventually leads to the apoptosis of hippocampal neurons.

Effect of acupuncture on HIF-1α/NLRP3 inflammatory signaling pathway in the rats with cerebral ischemia-reperfusion injury

To observe the effects of Xingnao Kaiqiao (regaining consciousness and opening orifices) acupuncture therapy on the expression of hypoxia-inducible factor 1α (HIF-1α) and Nod-like receptor protein 3 (NLRP3) in cerebral ischemia-reperfusion rats, and to explore the mechanism of acupuncture against cerebral ischemia-reperfusion injury. Seventy-two male SD rats were randomly divided into a sham-operation group, a model group, an acupuncture group and a non-point acupuncture group, with 18 rats in each one. Using modified Longa thread embolization method, the rat model of acute focal cerebral ischemia was prepared; and after 2 h ischemia, the reperfusion was performed to prepared the model of cerebral ischemia-reperfusion. Immediately after reperfusion, Xingnao Kaiqiao acupuncture method was applied to bilateral "Neiguan" (PC 6) and "Shuigou" (GV 26) in the acupuncture group, while in the non-point acupuncture group, acupuncture was delivered at non-points and all of the needles were retained for 30 min in these two groups. The samples were collected 24 h after reperfusion in the rats of each group. Zea-Longa neurological deficit score was used to evaluate the degree of cerebral neurological impairment, TTC staining was adopted to observe the volume percentage of cerebral infarction, HE staining was provided to observe the morphological changes of brain, and Western blot was applied for detecting the expression of HIF-1α and NLRP3 proteins in the cerebral cortex on the right side. Compared with the sham-operation group, neurological deficit score and volume percentage of cerebral infarction were increased in the model group (P<0.01), and HIF-1α and NLRP3 protein expression was elevated (P<0.01). Compared with the model group, neurological deficit score and volume percentage of cerebral infarction were decreased (P<0.01), and HIF-1α and NLRP3 protein expression was lower (P<0.01) in the acupuncture group. There was no significant difference in above indexes in the non-point acupuncture group compared with the model group (P>0.05). Compared with the sham-operation group, the brain tissue of the rats in the model group and the non-point acupuncture group was loose and edema, and the nuclei were shriveled. The brain tissue morphology in the acupuncture group was similar to that of the sham-operation group. Acupuncture can alleviate cerebral ischemia-reperfusion injury, and its mechanism may be related to the regulation of HIF-1α/NLRP3 signaling pathway to attenuate inflammatory response.

Neuroprotective Effects of Tryptanthrin-6-Oxime in a Rat Model of Transient Focal Cerebral Ischemia.

The activation of c-Jun N-terminal kinase (JNK) plays an important role in stroke outcomes. Tryptanthrin-6-oxime (TRYP-Ox) is reported to have high affinity for JNK and anti-inflammatory activity and may be of interest as a promising neuroprotective agent. The aim of this study was to investigate the neuroprotective effects of TRYP-Ox in a rat model of transient focal cerebral ischemia (FCI), which involved intraluminal occlusion of the left middle cerebral artery (MCA) for 1 h. Animals in the experimental group were administered intraperitoneal injections of TRYP-Ox 30 min before reperfusion and 23 and 47 h after FCI. Neurological status was assessed 4, 24, and 48 h following FCI onset. Treatment with 5 and 10 mg/kg of TRYP-Ox decreased mean scores of neurological deficits by 35-49 and 46-67% at 24 and 48 h, respectively. At these doses, TRYP-Ox decreased the infarction size by 28-31% at 48 h after FCI. TRYP-Ox (10 mg/kg) reduced the content of interleukin (IL) 1β and tumor necrosis factor (TNF) in the ischemic core area of the MCA region by 33% and 38%, respectively, and attenuated cerebral edema by 11% in the left hemisphere, which was affected by infarction, and by 6% in the right, contralateral hemisphere 24 h after FCI. TRYP-Ox reduced c-Jun phosphorylation in the MCA pool at 1 h after reperfusion. TRYP-Ox was predicted to have high blood-brain barrier permeability using various calculated descriptors and binary classification trees. Indeed, reactive oxidant production was significantly lower in the brain homogenates from rats treated with TRYP-Ox versus that in control animals. Our data suggest that the neuroprotective activity of TRYP-Ox may be due to the ability of this compound to inhibit JNK and exhibit anti-inflammatory and antioxidant activity. Thus, TRYP-Ox may be considered a promising neuroprotective agent that potentially could be used for the development of new treatment strategies in cerebral ischemia.

Preclinical models of middle cerebral artery occlusion: new imaging approaches to a classic technique.

Stroke remains a major burden on patients, families, and healthcare professionals, despite major advances in prevention, acute treatment, and rehabilitation. Preclinical basic research can help to better define mechanisms contributing to stroke pathology, and identify therapeutic interventions that can decrease ischemic injury and improve outcomes. Animal models play an essential role in this process, and mouse models are particularly well-suited due to their genetic accessibility and relatively low cost. Here, we review the focal cerebral ischemia models with an emphasis on the middle cerebral artery occlusion technique, a "gold standard" in surgical ischemic stroke models. Also, we highlight several histologic, genetic, and in vivo imaging approaches, including mouse stroke MRI techniques, that have the potential to enhance the rigor of preclinical stroke evaluation. Together, these efforts will pave the way for clinical interventions that can mitigate the negative impact of this devastating disease.

Increasing reproducibility in preclinical stroke research: the correlation of immunofluorescence intensity measurements and Western blot analyses strongly depends on antibody clonality and tissue pre-treatment in a mouse model of focal cerebral ischemia.

In the setting of stroke, ischemia not only impairs neuronal function, but also detrimentally affects the different components of the neurovascular unit, which are shown to be involved in the transition from reversible to long-lasting tissue damage. In this context, the glial proteins myelin basic protein (MBP) and the 2',3'-cyclic-nucleotide 3'-phosphodiesterase (CNP) as well as the vasculature-associated basement membrane proteins laminin and collagen IV have been identified as ischemia-sensitive elements. However, available data from immunofluorescence and Western blot analyses are often found to be contradictory, which renders interpretation of the respective data rather difficult. Therefore, the present study investigates the impact of tissue pre-treatment and antibody clonality on immunofluorescence measurements of the mentioned proteins in a highly reproducible model of permanent middle cerebral artery occlusion. Here, immunofluorescence labeling using polyclonal antibodies revealed an increased immunofluorescence intensity of MBP, CNP, laminin and collagen IV in ischemic areas, although Western blot analyses did not reveal increased protein levels. Importantly, contrary to polyclonal antibodies, monoclonal ones did not provide increased fluorescence intensities in ischemic areas. Further, we were able to demonstrate that different ways of tissue pre-treatment including paraformaldehyde fixation and antigen retrieval may not only impact on fluorescence intensity measurements in general, but rather one-sidedly affect either ischemic or unaffected tissue. Therefore, immunofluorescence intensity measurements do not necessarily correlate with the actual protein levels, especially in ischemia-affected tissue and should always be complemented by different techniques to enhance reproducibility and to hopefully overcome the translational roadblock from bench to bedside.

Temporal patterns and distribution of pyroptosis-related molecules and effects of human mesenchymal stem cells on pyroptosis following cerebral ischemia/reperfusion in rats

ObjectivesPyroptosis is a new type of programmed cell death that has a strong proinflammatory effect. The present study investigated the dynamic changes of pyroptosis-related molecules and the effect of mesenchymal stem cells (MSCs) on pyroptosis following cerebral ischemia/reperfusion (I/R). Materials and MethodsThe temporal pattern and cellular distribution of caspase-1, Gasdermin D and E (GSDMD and GSDME) in the peri-infarct area, and the effect of human MSCs on GSDMD, IL-1β, IL-18, Lactate dehydrogenase (LDH) and neurological function were studied in a rat model of transient focal cerebral ischemia. ResultsThe expression of caspase-1 mRNA increased with time, with a protein level of pro-caspase-1 comparable to its mRNA level, while the level of cleaved-caspase-1 protein peaked at 48 h following I/R. Increased levels of GSDMD mRNA and protein were also observed, with a peak level at 24 h. There were no significant changes in GSDME mRNA or protein expression after I/R. In regards to changes in the number of cells expressing GSDMD after I/R, that for neurons was more significant than those for microglia and astrocytes. The modified neurological severity score discrepancy and the expression of GSDMD showed no significant differences within 24 h following I/R between the MSC- and NS-treated groups, but MSCs treatment promoted the secretion of IL-1β, IL-18 and LDH. ConclusionsIn the early stage of cerebral infarction in rats, there were dynamic changes in pyroptosis-related molecules (caspase-1 and GSDMD), but MSCs showed no effect on the levels of GSDMD or neurological function.

Fucoidan (A Sulfated Polysaccharide) and Cerebroprotein in Combination Alleviate the Neuroinflammation-mediated Neural Damage and Functional Deficits in the Focal Cerebral Ischemia Model of Rat

Cerebral ischemic reperfusion injury could emanate a cascade of events ensuing in neural death and severe neurobehavioural deficits. The currently available interventions have failed to target the multimodal, interlinked mechanisms that operate cerebral ischemia-induced damage and functional loss. So an integrative intervention has become a mandate to overcome the deleterious mechanisms involved in cerebral ischemic pathophysiology. In this study, adult male Sprague dawley rats were exposed to 2 hours of right middle cerebral artery occlusion (rMCAo) followed by reperfusion, and the intervention group received Fucoidan alone at a dose of 50 mg/kg, i.p (intraperitoneal), Cerebrolysin alone at a dose of 2.5 mg/kg body weight and the combination of both. The sham rats were exposed to surgical procedures, except for the rMCAo. The assessments of the groups were made 24 h after the rMCAo. The stand-alone treatment with Fucoidan, Cerebrolysin has shown a better outcome in the neurobehavioral and, histopathological assessments and the combination has made a significant reduction in the neurological deficits and the infarct volume when compared to the standalone groups. The BBB integrity was well preserved in the combination group when compared with the lesion and standalone groups. Moreover, the combined intervention reduced the level of pro-inflammatory cytokines TNFα, NFkB, IL1α, IL1-β, IL-6, CD68, COX-2, and mRNA expression of inflammatory genes IL1α, IL1-β, IL-6, IBA-1, and COX-2 effectively. In conclusion, the present study suggests that rMCAo induced neuroinflammation and neurobehavioural alterations were attenuated by intervention with a combination of Fucoidan and cerebrolysin; Further, Fucoidan and Cerebrolysin combination improved the ischemic tolerance level by promoting the proteins and genes that regulate the inflammatory cytokines and in aiding better recovery after ischemic reperfusion injury.

Combination treatment of Danggui Buxue Decoction and endothelial progenitor cells can enhance angiogenesis in rats with focal cerebral ischemia and hyperlipidemia

Ethnopharmacological relevanceDanggui Buxue Decoction (DBD) is a classic prescription of traditional Chinese medicine that is mainly used for treating clinical anemia for more than 800 years. This prescription has been utilized for nourishing “Qi” and enriching “Blood” for women suffering from menopausal symptoms. Meanwhile, DBD has the role of improving angiogenesis and promoting the neuroprotective functions. Bone marrow-derived endothelial progenitor cells (EPCs) was suboptimal to treat the focal cerebral ischemia (FCI). Thus, it's may be a novel strategy of DBD combined with EPCs transplantation for the FCI. Aim of the studyTo investigate the mechanistic effects of DBD in combination with EPCs transplantation to improve behavioral function of the FCI and hyperlipidemia. Materials and methodsWe used rats with hyperlipidemia to develop a FCI model using photo-thrombosis, and treated the DBD in combination with EPCs transplantation. We adopted the Modified Neurological Severity Score to evaluate the neurological deficit, undertook the 2,3,5-triphenyltetrazolium chloride staining to calculate the total infarct volume. We carried out the RT-qPCR, Immunohistochemical analyses, TUNEL, ELISA, and Western blotting to measure the gene and protein levels which related to anti-apoptosis mechanisms and angiogenesis. ResultsAdministration of DBD in combination with EPCs transplantation was found to improve behavioral function, reducing the infarct volume and decrease the level of total-cholesterole (TC) and low-density lipoprotein-cholesterol (LDL-C). Treatment of DBD plus EPCs increased the mRNA and protein expression of vascular endothelial growth factor A, fibroblastic growth factor-2, and angiopoietin-1 and decreased the apoptosis of endothelial cells by activating the phosphoinositide 3-kinase/protein kinase B/Bcl-xL/Bcl-2 associated death promoter (PI3K/Akt/BAD) pathway and promoting activation of the extracellular signal-regulated kinase (ERK) pathway, which induced angiogenesis directly. ConclusionsOur findings provided that DBD administration combined with EPCs transplantation promoted reconstruction of nervous function. This was achieved by enhancing expression of the growth factors related to anti-apoptosis mechanisms and angiogenesis thanks to regulation of the PI3K/Akt/BAD and ERK signaling pathways, and might be relate to the lowering of TC and LDL-C levels.

Nootropic Activity of Prospekta in a Blind Placebo-Controlled Study in a Model of Focal Cerebral Ischemia in Rats.

Analysis of the pharmacological activity of the original drug Prospekta in a rat model of focal cerebral ischemia revealed its nootropic effect: course treatment in the post-ischemic period led to recovery of the neurological status of animals at the peak of neurological deficit. Evaluation of the therapeutic potential of the drug in morphological and functional CNS disorders allowed us to conclude that it is advisable to carry out further studies of its biological activity at the preclinical stage (the results obtained in animals were successfully confirmed in a clinical trial of drug efficacy in the treatment of moderate cognitive disorders in the early recovery period after ischemic stroke). Studies of the nootropic activity in other pathologies of the nervous system are also promising.

Photothrombotic Middle Cerebral Artery Occlusion in Mice: A Novel Model of Ischemic Stroke.

Stroke is one of the main causes of death and disability worldwide. Over the past decades, several animal models of focal cerebral ischemia have been developed allowing to investigate pathophysiological mechanisms underlying stroke progression. Despite intense preclinical research efforts, the need for noninvasive mouse models of vascular occlusion targeting the middle cerebral artery yet avoiding mechanical intervention is still pressing. Here, by applying the photothrombotic stroke model to the distal branch of the middle cerebral artery, we developed a novel strategy to induce a targeted occlusion of a large blood vessel in mice. This approach induces unilateral damage encompassing most of the dorsal cortex from the motor up to the visual regions 1 week after stroke. Pronounced limb dystonia one day after the damage is partially recovered after one week. Furthermore, we observe the insurgence of blood vessel leakage and edema formation in the peri-infarct area. Finally, this model elicits a notable inflammatory response revealed as a strong increase in astrocyte density and morphologic complexity in the perilesional region of the cortex compared with both other regions of the ipsilesional and contralesional hemispheres, and in sham-operated mice. To conclude, the stroke model we developed induces in mice the light-mediated occlusion of one of the main targets of human ischemic stroke, the middle cerebral artery, free from the limitations of commonly used preclinical models.

Embracing Heterogeneity in The Multicenter Stroke Preclinical Assessment Network (SPAN) Trial.

The Stroke Preclinical Assessment Network (SPAN) is a multicenter preclinical trial platform using rodent models of transient focal cerebral ischemia to address translational failure in experimental stroke. In addition to centralized randomization and blinding and large samples, SPAN aimed to introduce heterogeneity to simulate the heterogeneity embodied in clinical trials for robust conclusions. Here, we report the heterogeneity introduced by allowing the 6 SPAN laboratories to vary most of the biological and experimental model variables and the impact of this heterogeneity on middle cerebral artery occlusion (MCAo) performance. We included the modified intention-to-treat population of the control mouse cohort of the first SPAN trial (n=421) and examined the biological and procedural independent variables and their covariance. We then determined their impact on the dependent variables cerebral blood flow drop during MCAo, time to achieve MCAo, and total anesthesia duration using multivariable analyses. We found heterogeneity in biological and procedural independent variables introduced mainly by the site. Consequently, all dependent variables also showed heterogeneity among the sites. Multivariable analyses with the site as a random effect variable revealed filament choice as an independent predictor of cerebral blood flow drop after MCAo. Comorbidity, sex, use of laser Doppler flow to monitor cerebral blood flow, days after trial onset, and maintaining anesthesia throughout the MCAo emerged as independent predictors of time to MCAo. Total anesthesia duration was predicted by most independent variables. We present with high granularity the heterogeneity introduced by the biological and model selections by the testing sites in the first trial of cerebroprotection in rodent transient filament MCAo by SPAN. Rather than trying to homogenize all variables across all sites, we embraced the heterogeneity to better approximate clinical trials. Awareness of the heterogeneity, its sources, and how it impacts the study performance may further improve the study design and statistical modeling for future multicenter preclinical trials.

MiR-181b promotes angiogenesis and neurological function recovery after ischemic stroke.

Promotion of new blood vessel formation is a new strategy for treating ischemic stroke. Non-coding miRNAs have been recently considered potential therapeutic targets for ischemic stroke. miR-181b has been shown to promote angiogenesis in hypoxia and traumatic brain injury model, while its effect on ischemic stroke remains elusive. In this study, we found that overexpression of miR-181b in brain microvascular endothelial cells subjected to oxygen-glucose deprivation in vitro restored cell proliferation and enhanced angiogenesis. In rat models of focal cerebral ischemia, overexpression of miR-181b reduced infarction volume, promoted angiogenesis in ischemic penumbra, and improved neurological function. We further investigated the molecular mechanism by which miR-181b participates in angiogenesis after ischemic stroke and found that miR-181b directly bound to the 3'-UTR of phosphatase and tensin homolog (PTEN) mRNA to induce PTEN downregulation, leading to activation of the protein kinase B (Akt) pathway, upregulated expression of vascular endothelial growth factors, down-regulated expression of endostatin, and promoted angiogenesis. Taken together, these results indicate that exogenous miR-181b exhibits neuroprotective effects on ischemic stroke through activating the PTEN/Akt signal pathway and promoting angiogenesis.

β2-Microglobulin exacerbates neuroinflammation, brain damage, and cognitive impairment after stroke in rats.

β2-Microglobulin (β2M), a component of the major histocompatibility complex class I molecule, is associated with aging-related cognitive impairment and Alzheimer's disease. Although upregulation of β2M is considered to be highly related to ischemic stroke, the specific role and underlying mechanistic action of β2M are poorly understood. In this study, we established a rat model of focal cerebral ischemia by occlusion of the middle cerebral artery. We found that β2M levels in the cerebral spinal fluid, serum, and brain tissue were significantly increased in the acute period but gradually decreased during the recovery period. RNA interference was used to inhibit β2M expression in the acute period of cerebral stroke. Tissue staining with 2,3,5-triphenyltetrazolium chloride and evaluation of cognitive function using the Morris water maze test demonstrated that decreased β2M expression in the ischemic penumbra reduced infarct volume and alleviated cognitive deficits, respectively. Notably, glial cell, caspase-1 (p20), and Nod-like receptor pyrin domain containing 3 (NLRP3) inflammasome activation as well as production of the inflammatory cytokines interleukin-1β, interleukin-6, and tumor necrosis factor-α were also effectively inhibited by β2M silencing. These findings suggest that β2M participates in brain injury and cognitive impairment in a rat model of ischemic stroke through activation of neuroinflammation associated with the NLRP3 inflammasome.

C-X-C chemokine receptor type 7 antibody enhances neural plasticity after ischemic stroke.

Stromal cell-derived factor-1 and its receptor C-X-C chemokine receptor 4 (CXCR4) have been shown to regulate neural regeneration after stroke. However, whether stromal cell-derived factor-1 receptor CXCR7, which is widely distributed in the developing and adult central nervous system, participates in neural regeneration remains poorly understood. In this study, we established rat models of focal cerebral ischemia by injecting endothelin-1 into the cerebral cortex and striatum. Starting on day 7 after injury, CXCR7-neutralizing antibody was injected into the lateral ventricle using a micro drug delivery system for 6 consecutive days. Our results showed that CXCR7-neutralizing antibody increased the total length and number of sprouting corticospinal tract fibers in rats with cerebral ischemia, increased the expression of vesicular glutamate transporter 1 and growth-related protein 43, markers of the denervated spinal cord synapses, and promoted the differentiation and maturation of oligodendrocyte progenitor cells in the striatum. In addition, CXCR7 antibody increased the expression of CXCR4 in the striatum, increased the protein expression of RAS and ERK1/2 associated with the RAS/ERK signaling pathway, and improved rat motor function. These findings suggest that CXCR7 improved neural functional recovery after ischemic stroke by promoting axonal regeneration, synaptogenesis, and myelin regeneration, which may be achieved by activation of CXCR4 and the RAS/ERK1/2 signaling pathway.

A Reliable Nonhuman Primate Model of Ischemic Stroke with Reproducible Infarct Size and Long-term Sensorimotor Deficits.

A nonhuman primate model of ischemic stroke is considered as an ideal preclinical model to replicate various aspects of human stroke because of their similarity to humans in genetics, neuroanatomy, physiology, and immunology. However, it remains challenging to produce a reliable and reproducible stroke model in nonhuman primates due to high mortality and variable outcomes. Here, we developed a focal cerebral ischemic model induced by topical application of 50% ferric chloride (FeCl3) onto the MCA-M1 segment through a cranial window in the cynomolgus monkeys. We found that FeCl3 rapidly produced a stable intraarterial thrombus that caused complete occlusion of the MCA, leading to the quick decrease of the regional cerebral blood flow in 10 min. A typical cortical infarct was detected 24 hours by magnetic resonance imaging (MRI) and was stable at least for 1 month after surgery. The sensorimotor deficit assessed by nonhuman primate stroke scale was observed at 1 day and up to 3 months after ischemic stroke. No spontaneous revascularization or autolysis of thrombus was observed, and vital signs were not affected. All operated cynomolgus monkeys survived. Our data suggested that FeCl3-induced stroke in nonhuman primates was a replicable and reliable model that is necessary for the correct prediction of the relevance of experimental therapeutic approaches in human beings.

Neuroprotective effects of meloxicam on transient brain ischemia in rats: the two faces of anti-inflammatory treatments.

The inflammatory response plays an important role in neuroprotection and regeneration after ischemic insult. The use of non-steroidal anti-inflammatory drugs has been a matter of debate as to whether they have beneficial or detrimental effects. In this context, the effects of the anti-inflammatory agent meloxicam have been scarcely documented after stroke, but its ability to inhibit both cyclooxygenase isoforms (1 and 2) could be a promising strategy to modulate post-ischemic inflammation. This study analyzed the effect of meloxicam in a transient focal cerebral ischemia model in rats, measuring its neuroprotective effect after 48 hours and 7 days of reperfusion and the effects of the treatment on the glial scar and regenerative events such as the generation of new progenitors in the subventricular zone and axonal sprouting at the edge of the damaged area. We show that meloxicam's neuroprotective effects remained after 7 days of reperfusion even if its administration was restricted to the two first days after ischemia. Moreover, meloxicam treatment modulated glial scar reactivity, which matched with an increase in axonal sprouting. However, this treatment decreased the formation of neuronal progenitor cells. This study discusses the dual role of anti-inflammatory treatments after stroke and encourages the careful analysis of both the neuroprotective and the regenerative effects in preclinical studies.

Endothelial cells regulate astrocyte to neural progenitor cell trans-differentiation in a mouse model of stroke

The concept of the neurovascular unit emphasizes the importance of cell-cell signaling between neural, glial, and vascular compartments. In neurogenesis, for example, brain endothelial cells play a key role by supplying trophic support to neural progenitors. Here, we describe a surprising phenomenon where brain endothelial cells may release trans-differentiation signals that convert astrocytes into neural progenitor cells in male mice after stroke. After oxygen-glucose deprivation, brain endothelial cells release microvesicles containing pro-neural factor Ascl1 that enter into astrocytes to induce their trans-differentiation into neural progenitors. In mouse models of focal cerebral ischemia, Ascl1 is upregulated in endothelium prior to astrocytic conversion into neural progenitor cells. Injecting brain endothelial-derived microvesicles amplifies the process of astrocyte trans-differentiation. Endothelial-specific overexpression of Ascl1 increases the local conversion of astrocytes into neural progenitors and improves behavioral recovery. Our findings describe an unexpected vascular-regulated mechanism of neuroplasticity that may open up therapeutic opportunities for improving outcomes after stroke.

Dexmedetomidine treatment prevents cerebral ischemic reperfusion injury through HIF-1α/Beclin1-mediated autophagy

ABSTRACT Objective Cerebral ischemic reperfusion injury (CIRI) is a common cerebrovascular disorder with high disability and morbidity that threatens human health. Former investigations found that dexmedetomidine (DEX) has a protective effect against CIRI, but regulatory mechanism is unclear. Methods The current study utilized C57BL/6 mice to establish a focal cerebral ischemic reperfusion model. Cerebral infarct volume was defined by 2, 3, 5-triphenyltetrazolium chloride (TTC) staining. BV2 cells and primary neurons were utilized for molecular mechanism studies after treatment with DEX or autophagy inhibitor 3-Methyladenine (3-Ma). Results Data revealed that DEX pretreatment protected nerves against CIRI. In vitro studies also found that DEX pretreatment enhanced microglial M2 polarization and protected against neuronal apoptosis by autophagy activation. Downregulation of hypoxia inducible factor (HIF)-1α or Beclin-1 inhibited the promotional effects of DEX on microglial M2 polarization and inhibited the protective effects of DEX against neuronal apoptosis. Conclusion The present study found that DEX treatment protects against CIRI by modulating microglial polarization via HIF-1α/Beclin1-mediated autophagy.

Brain injury triggers cell-type-specific and time-dependent endoplasmic reticulum stress responses.

The unfolded protein response (UPR) is a signal transduction network that responds to endoplasmic reticulum (ER) stress by coordinating protein homeostasis to maintain cell viability. The UPR can also trigger cell death when adaptive responses fail to improve protein homeostasis. Despite accumulating evidence suggesting that the UPR plays a role in neurodegenerative diseases and brain insults, our understanding of how ER stress is induced under neuropathological conditions is limited. Here, we investigated the cell- and time-specific patterns of the ER stress response after brain injury using ER stress-activated indicator (ERAI) mice, which enable monitoring of the UPR in vivo via increased fluorescence of a spliced XBP-1 protein fused with the green fluorescent protein (GFP) variant Venus. Following cortical stab injury of ERAI mice, the GFP signal and number of GFP+ cells increased in the ipsilateral cortex throughout the observation period (6h to 7 days post-injury), confirming the induction of the UPR. GFP signals were observed in injured neurons early (from 6h) after brain injury. However, non-neuronal cells, mainly endothelial cells followed by astrocytes, accounted for the majority of GFP+ cells after brain injury. Similar results were obtained in a mouse model of focal cerebral ischemia. These findings suggest that activation of the UPR in both neuronal and non-neuronal cells, especially endothelial cells and astrocytes, may play an important role in and could be a potential therapeutic target for acute brain injuries.

Human-derived hair follicle stem cells and hydrogen sulfide on focal cerebral ischemia model: A comparative evaluation of radiologic, neurobehavioral and immunohistochemical results

The present study investigated the effects of intracerebral human-derived hair follicle stem cells (HFBSCs), whether alone or in combination with hydrogen sulfide (H2S) in a rat model of focal cerebral ischemia. The rats were randomly assigned into 4 groups (n = 10): Control (phosphate buffered saline (PBS)), Group A (at 24 h post-middle cerebral artery occlusion(MCAo), stereotaxic intracerebral, 1,0 × 106, total 10 μL HFBSCs), Group B (3–14 d post-MCAo, intraperitoneal (i.p.), 25 μM/kg/day H2S), Group AB (HFBSCs + H2S). Cranial magnetic resonance images were recorded on postoperative 1st and 28th days. Three dimensional analysis was performed to calculate the infarct volumes. Rotarod and cylinder tests were performed after MCAo and finally all rats were euthanized by cardiac perfusion at 28 days after MCAo for immunohistochemical analysis. The reduction in infarct volumes of rats receiving HFBSC was significant. The cranial infarct volume on the postoperative 28th day was significantly higher in the group in which H2S was administered alone compared to the HFBSC alone group. All animals showed steadily improved spontaneous locomotor activity from day 7 post-MCAo on rotarod test, from day 1 on cylinder test, but showed no significant differences at all times. In all groups, the grading scores of CD34, CD5, CD11b and GFAP immunohistochemical markers did not differ significantly. In conclusion, intracerebral HFBSC treatment after 24 h of ischemic stroke may be an effective way to reduce the cranial infarct volume, whereas H2S treatment alone or in combination with HFBSC may not be sufficient for ischemic brain injury.