MiR-126 Contributes to Human Umbilical Cord Blood Cell-Induced Neurorestorative Effects After Stroke in Type-2 Diabetic Mice

Exosomal MicroRNA: an Effective Strategy for the Treatment of Intracerebral Hemorrhage

Intracerebral hemorrhage is a devastating type of stroke, and its pathological mechanism is very complex. Surgical treatment can effectively treat the primary injury caused by mechanical compression of hematoma after intracerebral hemorrhage. However, there is no effective treatment for the secondary injury caused by a series of pathological processes caused by extravasation of blood components, including inflammatory response, oxidative stress, and excitotoxicity. Therefore, there is an urgent need to develop a novel treatment regimen that can reverse the secondary damage of intracerebral hemorrhage. In recent years, as a powerful biomarker, the role of microRNAs (miRNAs) in diseases has been gradually disclosed. As nanocarriers, the miRNAs delivered by exosomes have become a new treatment method and are widely used in the treatment of various diseases. In this paper, the research progress on the mechanism of exosomal miRNAs in intracerebral hemorrhage and its value in prevention, diagnosis, and prognosis is summarized, hoping to provide some reference for the application of exosomal miRNAs in clinical treatment of intracerebral hemorrhage.

Nose-to-brain delivery of stem cells in stroke: the role of extracellular vesicles

Stem cell transplantation offers a promising therapy that can be administered days, weeks, or months after a stroke. We recognize 2 major mitigating factors that remain unresolved in cell therapy for stroke, notably: (1) well-defined donor stem cells and (2) mechanism of action. To this end, we advance the use of ProtheraCytes, a population of non-adherent CD34+ cells derived from human peripheral blood and umbilical cord blood, which have been processed under good manufacturing practice, with testing completed in a phase 2 clinical trial in post-acute myocardial infarction (NCT02669810). We also reveal a novel mechanism whereby ProtheraCytes secrete growth factors and extracellular vesicles (EVs) that are associated with angiogenesis and vasculogenesis. Our recent data revealed that intranasal transplantation of ProtheraCytes at 3 days after experimentally induced stroke in adult rats reduced stroke-induced behavioral deficits and histological damage up to 28 days post-stroke. Moreover, we detected upregulation of human CD63+ EVs in the ischemic brains of stroke animals that were transplanted with ProtheraCytes, which correlated with increased levels of DCX-labeled neurogenesis and VEGFR1-associated angiogenesis and vasculogenesis, as well as reduced Iba1-marked inflammation. Altogether, these findings overcome key laboratory-to-clinic translational hurdles, namely the identification of well-characterized, clinical grade ProtheraCytes and the elucidation of a potential CD63+ EV-mediated regenerative mechanism of action. We envision that additional translational studies will guide the development of clinical trials for intranasal ProtheraCytes allografts in stroke patients, with CD63 serving as a critical biomarker.

Understanding the multifaceted role of miRNAs in Alzheimer's disease pathology

Small non-coding RNAs (miRNAs) regulate gene expression by binding to mRNA and mediating its degradation or inhibiting translation. Since miRNAs can regulate the expression of several genes, they have multiple roles to play in biological processes and human diseases. The majority of miRNAs are known to be expressed in the brain and are involved in synaptic functions, thus marking their presence and role in major neurodegenerative disorders, including Alzheimer's disease (AD). In AD, amyloid beta (Aβ) plaques and neurofibrillary tangles (NFTs) are known to be the major hallmarks. The clearance of Aβ and tau is known to be associated with miRNA dysregulation. In addition, the β-site APP cleaving enzyme (BACE 1), which cleaves APP to form Aβ, is also found to be regulated by miRNAs, thus directly affecting Aβ accumulation. Growing evidences suggest that neuroinflammation can be an initial event in AD pathology, and miRNAs have been linked with the regulation of neuroinflammation. Inflammatory disorders have also been associated with AD pathology, and exosomes associated with miRNAs are known to regulate brain inflammation, suggesting for the role of systemic miRNAs in AD pathology. Several miRNAs have been related in AD, years before the clinical symptoms appear, most of which are associated with regulating the cell cycle, immune system, stress responses, cellular senescence, nerve growth factor (NGF) signaling, and synaptic regulation. Phytochemicals, especially polyphenols, alter the expression of various miRNAs by binding to miRNAs or binding to the transcriptional activators of miRNAs, thus control/alter various metabolic pathways. Awing to the sundry biological processes being regulated by miRNAs in the brain and regulation of expression of miRNAs via phytochemicals, miRNAs and the regulatory bioactive phytochemicals can serve as therapeutic agents in the treatment and management of AD.

Human umbilical cord mesenchymal stem cells in diabetes mellitus and its complications: applications and research advances

Diabetes mellitus and its complications pose a major threat to global health and affect the quality of life and life expectancy of patients. Currently, the application of traditional therapeutic drugs for diabetes mellitus has great limitations and can only temporarily control blood glucose but not fundamentally cure it. Mesenchymal stem cells, as pluripotent stromal cells, have multidirectional differentiation potential, high self-renewal, immune regulation, and low immunogenicity, which provide a new idea and possible development direction for diabetes mellitus treatment. Regenerative medicine with mesenchymal stem cells treatment as the core treatment will become another treatment option for diabetes mellitus after traditional treatment. Recently, human umbilical cord mesenchymal stem cells have been widely used in basic and clinical research on diabetes mellitus and its complications because of their abundance, low ethical controversy, low risk of infection, and high proliferation and differentiation ability. This paper reviews the therapeutic role and mechanism of human umbilical cord mesenchymal stem cells in diabetes mellitus and its complications and highlights the challenges faced by the clinical application of human umbilical cord mesenchymal stem cells to provide a more theoretical basis for the application of human umbilical cord mesenchymal stem cells in diabetes mellitus patients.

The role of microRNA in neuronal inflammation and survival in the post ischemic brain: a review

Each year, more than 790 000 people in the United States suffer from a stroke. Although progress has been made in diagnosis and treatment of ischemic stroke (IS), new therapeutic interventions to protect the brain during an ischemic insult is highly needed. MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression post-transcriptionally. Growing evidence suggests that miRNAs have a profound impact on ischemic stroke progression and are potential targets of novel treatments. Notably, inflammatory pathways play an important role in the pathogenesis of ischemic stroke and its pathophysiologic progression. Experimental and clinical studies have illustrated that inflammatory molecular events collaboratively contribute to neuronal and glial cell survival, edema formation and regression, and vascular integrity. In the present review, we examine recent discoveries regarding miRNAs and their roles in post-ischemic stroke neuropathogenesis.

Transplantation of Exercise-Induced Extracellular Vesicles as a Promising Therapeutic Approach in Ischemic Stroke

Clinical evidence affirms physical exercise is effective in preventive and rehabilitation approaches for ischemic stroke. This sustainable efficacy is independent of cardiovascular risk factors and associates substantial reprogramming in circulating extracellular vesicles (EVs). The intricate journey of pluripotent exercise-induced EVs from parental cells to the whole-body and infiltration to cerebrovascular entity offers several mechanisms to reduce stroke incidence and injury or accelerate the subsequent recovery. This review delineates the potential roles of EVs as prospective effectors of exercise. The candidate miRNA and peptide cargo of exercise-induced EVs with both atheroprotective and neuroprotective characteristics are discussed, along with their presumed targets and pathway interactions. The existing literature provides solid ground to hypothesize that the rich vesicles link exercise to stroke prevention and rehabilitation. However, there are several open questions about the exercise stressors which may optimally regulate EVs kinetic and boost brain mitochondrial adaptations. This review represents a novel perspective on achieving brain fitness against stroke through transplantation of multi-potential EVs generated by multi-parental cells, which is exceptionally reachable in an exercising body.

Therapeutic Potentials of MicroRNA-126 in Cerebral Ischemia

Stroke is a leading cause of death and disability worldwide. It is among the most common neurological disorders with an 8-10% lifetime risk. Ischemic stroke accounts for about 85% of all strokes and damages the brain tissue via various damaging mechanisms. Following cerebral ischemia, the disrupted blood-brain barrier (BBB) leads to cerebral edema formation caused by activation of oxidative stress, inflammation, and apoptosis, targeting primarily endothelial cells. Activation of the protective mechanisms might favor fewer damages to the neural tissue. MicroRNA (miR)-126 is an endothelial cell-specific miR involved in angiogenesis. MiR-126 orchestrates endothelial progenitor cell functions under hypoxic conditions and could inhibit ischemia-induced oxidative stress and inflammation. It alleviates the BBB disruption by preventing an augment in matrix metalloproteinase level and halting the decrease in the junctional proteins, including zonula occludens-1 (ZO-1), claudin-5, and occludin levels. Moreover, miR-126 enhances post-stroke angiogenesis and neurogenesis. This work provides a therapeutic perspective for miR-126 as a new approach to treating cerebral ischemia.

Meta-analysis of the characteristic expression of circulating microRNA in type 2 diabetes mellitus with acute ischemic cerebrovascular disease

OBJECTIVE

To comprehensively evaluate the characteristics of the circulating microRNA expression profile in type 2 diabetic patients with acute ischemic cerebrovascular disease by systematic evaluation and meta-analysis.

METHODS

The literatures up to March 2022 related to circulating microRNA and acute ischemic cerebrovascular disease in type 2 diabetes mellitus were searched and screened from multiple databases. The NOS quality assessment scale was used to evaluate methodological quality. Heterogeneity tests and statistical analyses of all data were performed by Stata 16.0. The differences in microRNA levels between groups were illustrated by the standardized mean difference (SMD) and 95% confidence interval (95% CI).

RESULTS

A total of 49 studies on 12 circulating miRNAs were included in this study, including 486 cases of type 2 diabetes complicated with acute ischemic cerebrovascular disease and 855 controls. Compared with the control group (T2DM group), miR-200a, miR-144, and miR-503 were upregulated and positively correlated with acute ischemic cerebrovascular disease in type 2 diabetes mellitus patients. Their comprehensive SMD and 95% CI were 2.71 (1.64~3.77), 5.77 (4.28~7.26) and 0.73 (0.27~1.19), respectively. MiR-126 was downregulated and negatively correlated with acute ischemic cerebrovascular disease in type 2 diabetes mellitus patients, its comprehensive SMD and 95% CI were -3.64 (-5.56~-1.72).

CONCLUSION

In type 2 diabetes mellitus patients with acute ischemic cerebrovascular disease, the expression of serum miR-200a, miR-503, plasma and platelet miR-144 was upregulated and the expression of serum miR-126 was downregulated. It may have diagnostic value in the early identification of type 2 diabetes mellitus with acute ischemic cerebrovascular disease.

Secondary White Matter Injury Mediated by Neuroinflammation after Intracerebral Hemorrhage and Promising Therapeutic Strategies of Targeting the NLRP3 Inflammasome

Intracerebral hemorrhage (ICH) is a neurological disease with high mortality and disability. Recent studies showed that white matter injury (WMI) plays an important role in motor dysfunction after ICH. WMI includes WMI proximal to the lesion and WMI distal to the lesion, such as corticospinal tract injury located at the cervical enlargement of the spinal cord after ICH. Previous studies have tended to focus only on gray matter (GM) injury after ICH, and fewer studies have paid attention to WMI, which may be one of the reasons for the poor outcome of previous drug treatments. Microglia and astrocyte-mediated neuroinflammation are significant mechanisms responsible for secondary WMI following ICH. The NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome activation, has been shown to exacerbate neuroinflammation and brain injury after ICH. Moreover, NLRP3 inflammasome is activated in microglia and astrocytes and exerts a vital role in microglia and astrocytes-mediated neuroinflammation. We speculate that NLRP3 inflammasome activation is closely related to the polarization of microglia and astrocytes and that NLRP3 inflammasome activation may exacerbate WMI by polarizing microglia and astrocytes to the pro-inflammatory phenotype after ICH, while NLRP3 inflammasome inhibition may attenuate WMI by polarizing microglia and astrocytes to the anti-inflammatory phenotype following ICH. Therefore, NLRP3 inflammasome may act as leveraged regulatory fulcrums for microglia and astrocytes polarization to modulate WMI and WM repair after ICH. This review summarized the possible mechanisms by which neuroinflammation mediated by NLRP3 inflammasome exacerbates secondary WMI after ICH and discussed the potential therapeutic targets.

Brain Microenvironment Responsive and Pro-Angiogenic Extracellular Vesicle-Hydrogel for Promoting Neurobehavioral Recovery in Type 2 Diabetic Mice After Stroke

Stroke patients with diabetes have worse neurological outcomes than non-diabetic stroke patients, and treatments beneficial for non-diabetic stroke patients are not necessarily effective for diabetic stroke patients. While stem cell-derived extracellular vesicles (EVs) show potential for treating stroke, the results remain unsatisfactory due to the lack of approaches for retaining and controlling EVs released into the brain. Herein, a glucose/reactive oxygen species dual-responsive hydrogel showing excellent injectability, biocompatibility, and self-healing capability is introduced as an EVs-loading vehicle and an intelligent EVs sustained releasing system in the brain. These EVs-hydrogels are developed via crosslinking of phenylboronic acid-modified hyaluronic acid and Poly vinyl alcohol, and fusion with neural stem cell-derived EVs. The results show EVs are stably incorporated into the hydrogels and can be controllably released in response to the brain microenvironment after stroke in type 2 diabetic mice. The EVs-hydrogels exert an excellent angiogenic effect, increasing the migration and tube formation of human umbilical vein endothelial cells. In addition, injection of EVs-hydrogels into the ischemic mouse brain enhances EVs retention and facilitates sustained release, promotes angiogenesis, and improves neurobehavioral recovery. These results suggest such a microenvironment responsive and sustained release EVs-hydrogel system offers a safe, and efficient therapy for diabetic stroke.

MiR-29a Family as a Key Regulator of Skeletal Muscle Dysplasia in a Porcine Model of Intrauterine Growth Retardation

MicroRNAs (miRNAs) play an essential role in many biological processes. In this study, miRNAs in the skeletal muscle of normal and intrauterine growth retardation (IUGR) neonatal piglets were identified by sequencing, and canonical miRNAs were functionally validated in vitro. A total of 403 miRNAs were identified in neonatal piglet skeletal muscle, among them 30 and 46 miRNAs were upregulated and downregulated in IUGR pigs, respectively. Upregulated miRNAs were mainly enriched in propanoate metabolism, endocytosis, beta-Alanine metabolism, gap junction, and tumor necrosis factor signaling pathway. Down-regulated miRNAs were mainly enriched in chemical carcinogenesis—receptor activation, endocytosis, MAPK signaling pathway, insulin resistance, and EGFR tyrosine kinase inhibitor resistance. Co-expression network analysis of umbilical cord blood and skeletal muscle miRNAs showed that the miR-29 family is an essential regulator of IUGR pigs. The dual-luciferase reporter system showed that IGF1 and CCND1 were target genes of the miR-29 family. Transfection of IUGR pig umbilical cord blood exosomes and miR-29a mimic significantly inhibited cell proliferation and promoted the expression of cellular protein degradation marker genes Fbxo32 and Trim63. In summary, these results enrich the regulatory network of miRNAs involved in skeletal muscle development in IUGR animals.

Delayed rFGF21 Administration Improves Cerebrovascular Remodeling and White Matter Repair After Focal Stroke in Diabetic Mice

Type 2 diabetes mellitus (T2DM) is a major comorbidity exacerbating ischemic brain injury and impairing post-stroke recovery. Our previous study suggested that recombinant human fibroblast growth factor (rFGF) 21 might be a potent therapeutic targeting multiple aspects of pathophysiology in T2DM stroke. This study aims to evaluate the potential effects of rFGF21 on cerebrovascular remodeling after T2DM stroke. Permanent distal middle cerebral artery occlusion was performed in heterozygous non-diabetic db/ + and homozygous diabetic db/db mice. Daily rFGF21 administration was initiated 1 week after stroke induction and maintained for up to 2 weeks thereafter. Multiple markers associated with post-stroke recovery, including angiogenesis, oligodendrogenesis, white matter integrity, and neurogenesis, were assessed up to 3 weeks after stroke. Our results showed an impairment in post-stroke vascular remodeling under T2DM condition, reflected by the decreased expression of trophic factors in brain microvessels and impairments of angiogenesis. The defected cerebrovascular remodeling was accompanied by the decreased oligodendrogenesis and neurogenesis. However, delayed rFGF21 administration normalized post-stroke hyperglycemia and improved neurological outcomes, which may partially be via the promotion of pro-angiogenic trophic factor expression in brain microvessels and cerebrovascular remodeling. The better cerebrovascular remodeling may also contribute to oligodendrogenesis, white matter integrity, and neurogenesis after T2DM stroke. Therefore, delayed rFGF21 administration may improve neurological outcomes in T2DM stroke mice, at least in part by normalizing the metabolic abnormalities and promoting cerebrovascular remodeling and white matter repair.

Human umbilical cord mesenchymal stem cells in type 2 diabetes mellitus: the emerging therapeutic approach

The umbilical cord has been proved to be an easy-access, reliable, and useful source of mesenchymal stem cells (MSC) for clinical applications due to its primitive, immunomodulatory, non-immunogenic, secretory and paracrine, migratory, proliferative, and multipotent properties. This set of characteristics has recently attracted great research interest in the fields of nanotechnology and regenerative medicine and cellular therapy. Accumulating evidence supports a pronounced therapeutic potential of MSC in many different pathologies, from hematology to immunology, wound-healing, tissue regeneration, and oncology. Diabetes mellitus, branded the epidemic of the century, is considered a chronic metabolic disorder, representing a major burden for health system sustainability and an important public health challenge to modern societies. The available treatments for type 2 diabetes mellitus (T2DM) still rely mainly on combinations of oral antidiabetic agents with lifestyle and nutritional adjustments. Despite the continuous development of novel and better hypoglycemic drugs, their efficacy is limited in the installment and progression of silent T2DM complications. T2DM comorbidities and mortality rates still make it a serious, common, costly, and long-term manageable disease. Recently, experimental models, preclinical observations, and clinical studies have provided some insights and preliminary promising results using umbilical cord MSCs to treat and manage diabetes. This review focuses on the latest research and applications of human-derived umbilical cord MSC in the treatment and management of T2DM, exploring and systematizing the key effects of both umbilical cord MSC and its factor-rich secretome accordingly with the major complications associated to T2DM.

New epigenetic players in stroke pathogenesis: From non-coding RNAs to exosomal non-coding RNAs

Non-coding RNAs (ncRNAs) have critical role in the pathophysiology as well as recovery after ischemic stroke. ncRNAs, particularly microRNAs, and the long non-coding RNAs (lncRNAs) are critical for angiogenesis and neuroprotection, and they have been suggested to be therapeutic, diagnostic and prognostic tools in cerebrovascular diseases, including stroke. Moreover, exosomes have been considered as nanocarriers capable of transferring various cargos, such as lncRNAs and miRNAs to recipient cells, with prominent inter-cellular roles in the mediation of neuro-restorative events following strokes and neural injuries. In this review, we summarize the pathogenic role of ncRNAs and exosomal ncRNAs in the stroke.

Exosomes in Ischemic Stroke

Ischemic stroke, a leading cause of mortality, results in severe neurological outcomes in the patients. Effective stroke therapies may significantly decrease the extent of injury. For this purpose, novel and efficient drug delivery strategies need to be developed. Among a myriad of therapeutic and drug delivery techniques, exosomes have shown promising results in ischemic stroke either by their intrinsic therapeutic characteristics, which can result in angiogenesis and neurogenesis or by acting as competent, biocompatible drug delivery vehicles to transport neurotherapeutic agents into the brain. In this review, we have discussed different methods of exosome isolation and cargo loading techniques, advantages and disadvantages of using exosomes as a drug delivery carrier and the therapeutic applications of exosomes with a focus on ischemic stroke therapy.

miR‑126 overexpression attenuates oxygen‑glucose deprivation/reperfusion injury by inhibiting oxidative stress and inflammatory response via the activation of SIRT1/Nrf2 signaling pathway in human umbilical vein endothelial cells

MicroRNA‑126 (miR‑126) has been reported to be implicated in the pathogenesis of cerebral ischemia/reperfusion (I/R) injury; however, its role is still unclear and requires further investigation. The objective of the present study was to determine the neuroprotective effect of miR‑126 overexpression against oxygen‑glucose deprivation/reoxygenation (OGD/R)‑induced human umbilical vein endothelial cell (HUVEC) injury, an in vitro model of cerebral I/R injury, and to further explore the role of the NAD‑dependent protein deacetylase sirtuin‑1 (SIRT1)/nuclear factor erythroid 2‑related factor 2 (Nrf2) signaling pathway in this process. The results of the present study revealed that miR‑126 expression was markedly reduced in HUVECs subjected to OGD/R treatment. Functional experiments demonstrated that transfection with miR‑126 mimics attenuated OGD/R‑induced down‑regulation of cell viability, and reversed OGD/R‑induced up‑regulation of lactate dehydrogenase release, apoptosis and caspase‑3 activity in HUVECs. Notably, OGD/R reduced SIRT1 and heme oxygenase‑1 expression, and induced the nuclear translocation of Nrf2, as demonstrated by the increase in cytoplasmic Nrf2 expression and the decrease in nuclear Nrf2 expression. Following transfection with miR‑126 mimics, these effects of OGD/R were reversed, indicating that miR‑126 overexpression promoted the SIRT1/Nrf2 signaling pathway. Additionally, miR‑126 mimics attenuated OGD/R‑induced cytotoxicity and apoptosis, which was blocked by inhibition of the SIRT1/Nrf2 signaling pathway followed by transfection with SIRT1‑small interfering RNA (siRNA). Furthermore, miR‑126 mimics decreased ROS generation and malondialdehyde content, and increased superoxide dismutase and glutathione peroxidase activity in HUVECs exposed to OGD/R, and these effects of miR‑126 mimics were also blocked by SIRT1‑siRNA. Additionally, the miR‑126 mimics‑induced the decreases in the levels of pro‑inflammatory cytokines, including tumor necrosis factor‑α, interleukin (IL)‑1β and IL‑6, and the miR‑126 mimics‑induced increase in anti‑inflammatory cytokines, including IL‑10, were reversed by SIRT1‑siRNA. Overall, these results suggested that miR‑126 overexpression attenuated OGD/R‑induced neurotoxicity to HUVECs by alleviating oxidative stress and the inflammatory response via promotion of the SIRT1/Nrf2 signaling pathway.

The Effects and Underlying Mechanisms of Cell Therapy on Blood-Brain Barrier Integrity After Ischemic Stroke

Ischemic stroke is one of the main causes of mortality and disability worldwide. However, efficient therapeutic strategies are still lacking. Stem/progenitor cell-based therapy, with its vigorous advantages, has emerged as a promising tool for the treatment of ischemic stroke. The mechanisms involve new neural cells and neuronal circuitry formation, antioxidation, inflammation alleviation, angiogenesis, and neurogenesis promotion. In the past decades, in-depth studies have suggested that cell therapy could promote vascular stabilization and decrease blood-brain barrier (BBB) leakage after ischemic stroke. However, the effects and underlying mechanisms on BBB integrity induced by the engrafted cells in ischemic stroke have not been reviewed yet. Herein, we will update the progress in research on the effects of cell therapy on BBB integrity after ischemic stroke and review the underlying mechanisms. First, we will present an overview of BBB dysfunction under the ischemic condition and cells engraftment for ischemic treatment. Then, we will summarize and discuss the current knowledge about the effects and underlying mechanisms of cell therapy on BBB integrity after ischemic stroke. In particular, we will review the most recent studies in regard to the relationship between cell therapy and BBB in tissue plasminogen activator (t-PA)-mediated therapy and diabetic stroke.

Exosomes from miRNA-126-modified endothelial progenitor cells alleviate brain injury and promote functional recovery after stroke

Aims

We previously showed that the protective effects of endothelial progenitor cells (EPCs)‐released exosomes (EPC‐EXs) on endothelium in diabetes. However, whether EPC‐EXs are protective in diabetic ischemic stroke is unknown. Here, we investigated the effects of EPC‐EXs on diabetic stroke mice and tested whether miR‐126 enriched EPC‐EXs (EPC‐EXs^miR126) have enhanced efficacy.

Methods

The db/db mice subjected to ischemic stroke were intravenously administrated with EPC‐EXs 2 hours after ischemic stroke. The infarct volume, cerebral microvascular density (MVD), cerebral blood flow (CBF), neurological function, angiogenesis and neurogenesis, and levels of cleaved caspase‐3, miR‐126, and VEGFR2 were measured on day 2 and 14.

Results

We found that (a) injected EPC‐EXs merged with brain endothelial cells, neurons, astrocytes, and microglia in the peri‐infarct area; (b) EPC‐EXs^miR126 were more effective than EPC‐EXs in decreasing infarct size and increasing CBF and MVD, and in promoting angiogenesis and neurogenesis as well as neurological functional recovery; (c) These effects were accompanied with downregulated cleaved caspase‐3 on day 2 and vascular endothelial growth factor receptor 2 (VEGFR2) upregulation till day 14.

Conclusion

Our results indicate that enrichment of miR126 enhanced the therapeutic efficacy of EPC‐EXs on diabetic ischemic stroke by attenuating acute injury and promoting neurological function recovery.

Mesenchymal stem cell-derived extracellular vesicle-based therapies protect against coupled degeneration of the central nervous and vascular systems in stroke

Stem cell-based treatments have been suggested as promising candidates for stroke. Recently, mesenchymal stem cells (MSCs) have been reported as potential therapeutics for a wide range of diseases. In particular, clinical trial studies have suggested MSCs for stroke therapy. The focus of MSC treatments has been directed towards cell replacement. However, recent research has lately highlighted their paracrine actions. The secretion of extracellular vesicles (EVs) is offered to be the main therapeutic mechanism of MSC therapy. However, EV-based treatments may provide a wider therapeutic window compared to tissue plasminogen activator (tPA), the traditional treatment for stroke. Exosomes are nano-sized EVs secreted by most cell types, and can be isolated from conditioned cell media or body fluids such as plasma, urine, and cerebrospinal fluid (CSF). Exosomes apply their effects through targeting their cargos such as microRNAs (miRs), DNAs, messenger RNAs, and proteins at the host cells, which leads to a shift in the behavior of the recipient cells. It has been indicated that exosomes, in particular their functional cargoes, play a significant role in the coupled pathogenesis and recovery of stroke through affecting the neurovascular unit (NVU). Therefore, it seems that exosomes could be utilized as diagnostic and therapeutic tools in stroke treatment. The miRs are small endogenous non-coding RNA molecules which serve as the main functional cargo of exosomes, and apply their effects as epigenetic regulators. These versatile non-coding RNA molecules are involved in various stages of stroke and affect stroke-related factors. Moreover, the involvement of aging-induced changes to specific miRs profile in stroke further highlights the role of miRs. Thus, miRs could be utilized as diagnostic, prognostic, and therapeutic tools in stroke. In this review, we discuss the roles of stem cells, exosomes, and their application in stroke therapy. We also highlight the usage of miRs as a therapeutic choice in stroke therapy.

Serum MicroRNA on inflammation: a literature review of mouse model studies

MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate target gene expression by binding to sequences in messenger RNA processing. Inflammation is a protective reaction from harmful stimuli. MiRNAs can be biomarkers of diseases related to inflammation and are widely expressed in serum. However, overall changes in serum miRNA levels during inflammation have yet to be observed. Here, we selected studies published until 20 January 2020 that examined miRNAs in mouse models of inflammation. Serum microRNA, inflammation, inflammatory and mouse were used as search terms to select articles from PubMed and MEDLINE. Among the articles, sepsis and 18 related miRNAs were mainly examined. Eleven miRNAs were related to brain disease and 10 with fibrosis. Seventeen injury-induced inflammatory disease studies were included, as well as other inflammatory diseases, such as metabolic disease, vascular disease, arthritis, asthma, autoimmune disease, inflammatory bowel disease, and thyroiditis. The data described miRNA-associated downstream pathways associated with inflammation as well as mitochondrial responses, oxidative responses, apoptosis, cell signalling, and cell differentiation. We expect that the data will inform future animal inflammation-related miRNA studies.

HUCBC Treatment Improves Cognitive Outcome in Rats With Vascular Dementia

Background and purpose: Vascular dementia (VaD) is the second common cause of dementia after Alzheimer's disease in older people. Yet, there are no FDA approved drugs specifically for VaD. In this study, we have investigated the therapeutic effects of human umbilical cord blood cells (HUCBC) treatment on the cognitive outcome, white matter (WM) integrity, and glymphatic system function in rats subject to a multiple microinfarction (MMI) model of VaD. Methods: Male, retired breeder rats were subjected to the MMI model (800 ± 100 cholesterol crystals/300 μl injected into the internal carotid artery), and 3 days later were treated with phosphate-buffered saline (PBS) or HUCBC (5 × 10⁶, i.v.). Sham rats were included as naïve control. Following a battery of cognitive tests, rats were sacrificed at 28 days after MMI and brains extracted for immunohistochemical evaluation and Western blot analysis. To evaluate the glymphatic function, fluorescent tracers (Texas Red dextran, MW: 3 kD and FITC-dextran, MW: 500 kD) was injected into the cisterna magna over 30 min at 14 days after MMI. Rats (3-4/group/time point) were sacrificed at 30 min, 3 h, and 6 h, and the tracer movement analyzed using laser scanning confocal microscopy. Results: Compared to control MMI rats, HUCBC treated MMI rats exhibit significantly improved short-term memory and long-term memory exhibited by increased discrimination index in novel object recognition task with retention delay of 4 h and improved novel odor recognition task with retention delay of 24 h, respectively. HUCBC treatment also improves spatial learning and memory as measured using the Morris water maze test compared to control MMI rats. HUCBC treatment significantly increases axon and myelin density increases oligodendrocyte and oligodendrocyte progenitor cell number and increases Synaptophysin expression in the brain compared to control MMI rats. HUCBC treatment of MMI in rats significantly improves glymphatic function by reversing MMI induced delay in the penetration of cerebrospinal fluid (CSF) into the brain parenchyma via glymphatic pathways and reversing delayed clearance from the brain. HUCBC treatment significantly increases miR-126 expression in serum, aquaporin-4 (AQP4) expression around cerebral vessels, and decreases transforming growth factor-β (TGF-β) protein expression in the brain which may contribute to HUCBC induced improved glymphatic function. Conclusions: HUCBC treatment of an MMI rat model of VaD promotes WM remodeling and improves glymphatic function which together may aid in the improvement of cognitive function and memory. Thus, HUCBC treatment warrants further investigation as a potential therapy for VaD.

Human umbilical cord blood cells rescued traumatic brain injury-induced cardiac and neurological deficits

Background

Traumatic brain injury (TBI) evokes neurological deficits and induces cardiac dysfunction. Treatment with human umbilical cord blood cells (HUCBCs) represents a potential therapeutic strategy for TBI-induced neurological deficits. The present study aimed to determine whether HUCBCs could ameliorate the cardiac dysfunction and neurological deficits induced by TBI.

Methods

Adult male C57BL/6J mice were subjected to controlled cortical impact (CCI)-induced TBI and were treated with either HUCBCs (1×10⁶) or phosphate-buffered saline (PBS), via tail vein injections, 3 days after TBI. Neurological and cognitive functions were subsequently evaluated at multiple time points after TBI and cardiac function was assessed by echocardiography 3 and 30 days after TBI. Brain and heart tissues were paraffin-embedded 30 days after TBI. Hematoxylin and eosin (H&E) staining was performed on brain tissue sections to calculate the brain damage volume, and Picro Sirius Red (PSR) staining was performed on heart tissue sections to evaluate myocardial fibrosis. Terminal deoxynucleotide transferase dUTP nick end labeling (TUNEL) staining was employed to assess cell apoptosis 30 days after TBI. Transforming growth factor-beta (TGF-β) and NADPH oxidase-2 (NOX2) levels were assessed to evaluate inflammation and oxidative stress levels 30 days after TBI.

Results

TBI elicited acute and chronic cardiac deficits, identified by decreased left ventricular ejection fraction (LVEF) and fractional shortening (LVFS) values 3 and 30 days after TBI, in addition to neurological and cognitive deficits. TBI mice treated with HUCBCs exhibited enhanced LVEF and FS values 30 days after TBI compared with untreated TBI controls. HUCBC treatment significantly improved neurological and cognitive functions and reduced cardiomyocyte apoptosis, inflammatory response, oxidative stress, and cardiac fibrosis in heart tissues 30 days after TBI.

Conclusions

TBI induced both neurological deficits and cardiac dysfunction in mice, which were ameliorated by HUCBC treatment. The anti-inflammatory activities of HUCBCs may contribute to these observed therapeutic effects.

Exosomal MicroRNA-126 from RIPC Serum Is Involved in Hypoxia Tolerance in SH-SY5Y Cells by Downregulating DNMT3B

Ischemic tolerance in the brain can be induced by transient limb ischemia, and this phenomenon is termed remote ischemic preconditioning (RIPC). It still remains elusive how this transfer of tolerance occurs. Exosomes can cross the blood-brain barrier, and some molecules may transfer neuroprotective signals from the periphery to the brain. Serum miRNA-126 is associated with ischemic stroke, and exosomal miRNA-126 has shown protective effects against acute myocardial infarction. Therefore, this study aims to explore whether exosomal miRNA-126 from RIPC serum can play a similar neuroprotective role. Exosomes were isolated from the venous serum of four healthy young male subjects, both before and after RIPC. Exosomal miRNA-126 was measured by real-time PCR. The miRNA-126 target sequence was predicted by bioinformatics software. SH-SY5Y neuronal cells were incubated with exosomes, and the cell cycle was analyzed by flow cytometry. The expression and activity of DNA methyltransferase (DNMT) 3B, a potential target gene of miRNA-126, were examined in SH-SY5Y cells. The cell viability of SH-SY5Y cells exposed to oxygen-glucose deprivation (OGD) was also investigated. To confirm the association between miRNA-126 and DNMT3B, we overexpressed miRNA-126 in SH-SY5Y cells using lentiviral transfection. miRNA-126 expression was upregulated in RIPC exosomes, and bioinformatics prediction showed that miRNA-126 could bind with DNMT3B. DNMT levels and DNMT3B activity were downregulated in SH-SY5Y cells incubated with RIPC exosomes. After overexpression of miRNA-126 in SH-SY5Y cells, global methylation levels and DNMT3B gene expression were downregulated in these cells, consistent with the bioinformatics predictions. RIPC exosomes can affect the cell cycle and increase OGD tolerance in SH-SY5Y cells. RIPC seems to have neuroprotective effects by downregulating the expression of DNMTs in neural cells through the upregulation of serum exosomal miRNA-126.

Implication of MicroRNA503 in Brain Endothelial Cell Function and Ischemic Stroke

The role of miR-503 in brain endothelium and ischemic stroke (IS) remains unclear. We aimed to study the relationship between plasma miR-503 and the onset time, severity, subtypes, and von Willebrand Factor (vWF) level in IS patients and to investigate the roles and underlying mechanisms of miR-503 in middle cerebral artery occlusion (MCAO) mice and cultured cerebral vascular endothelial cells (ECs). In MCAO mice, the effects of plasma from acute severe IS patients (ASS) with or without miR-503 antagomir on brain and ECs damage were determined. In cultured human ECs, the effects of miR-503 overexpression or knockdown on the monolayer permeability, apoptosis, ROS, and NO generation were investigated. For mechanism study, the PI3K/Akt/eNOS pathway, cleaved caspase-3, and bcl-2 were analyzed. Results showed that plasma miR-503 was significantly increased in IS patients, especially in acute period and severe cases and subtypes of LAA and TACI, and was positively correlated with vWF. Logistic analysis indicated that miR-503 was an independent risk factor for IS, with the area under curve of 0.796 in ROC analysis. In MCAO mice, ASS pretreatment aggravated neurological injury, BBB damage, brain edema, CBF reduction, and decreased NO production while increased apoptosis and ROS generation in brain ECs, which were partly abolished by miR-503 antagomir. In cultured ECs, miR-503 overexpression and knockdown confirmed its effects on regulating monolayer permeability, cell apoptosis, NO, and ROS generation via PI3K/Akt/eNOS pathway or bcl-2 and cleaved caspase-3 proteins. These together indicate that miR-503 is a promising biomarker and novel therapeutic target for IS.

CD133+Exosome Treatment Improves Cardiac Function after Stroke in Type 2 Diabetic Mice

Cardiac complications post-stroke are common, and diabetes exacerbates post-stroke cardiac injury. In this study, we tested whether treatment with exosomes harvested from human umbilical cord blood derived CD133+ cells (CD133+Exo) improves cardiac function in type 2 diabetes mellitus (T2DM) stroke mice. Adult (3-4 m), male, BKS.Cg-m+/+Lepr^db/J (db/db, T2DM) and non-DM (db+) mice were randomized to sham or photothrombotic stroke groups. T2DM-stroke mice were treated with phosphate-buffered saline (PBS) or CD133+Exo (20 μg, i.v.) at 3 days after stroke. T2DM sham and T2DM+CD133+Exo treatment groups were included as controls. Echocardiography was performed, and mice were sacrificed at 28 days after stroke. Cardiomyocyte hypertrophy, myocardial capillary density, interstitial fibrosis, and inflammatory factor expression were measured in the heart. MicroRNA-126 expression and its target gene expression were measured in the heart. T2DM mice exhibit significant cardiac deficits such as decreased left ventricular ejection fraction (LVEF) and shortening fraction (LVSF), increased left ventricular diastolic dimension (LVDD), and reduced heart rate compared to non-DM mice. Stroke in non-DM and T2DM mice significantly decreases LVEF compared to non-DM and T2DM-sham, respectively. Cardiac dysfunction is worse in T2DM-stroke mice compared to non-DM-stroke mice. CD133+Exo treatment of T2DM-stroke mice significantly improves cardiac function identified by increased LVEF and decreased LVDD compared to PBS treated T2DM-stroke mice. In addition, CD133+Exo treatment significantly decreases body weight and blood glucose but does not decrease lesion volume in T2DM-stroke mice. CD133+Exo treatment of T2DM mice significantly decreases body weight and blood glucose but does not improve cardiac function. CD133+Exo treatment in T2DM-stroke mice significantly decreases myocardial cross-sectional area, interstitial fibrosis, transforming growth factor beta (TGF-β), numbers of M1 macrophages, and oxidative stress markers 4-HNE (4-hydroxynonenal) and NADPH oxidase 2 (NOX2) in heart tissue. CD133+Exo treatment increases myocardial capillary density in T2DM-stroke mice as well as upregulates endothelial cell capillary tube formation in vitro. MiR-126 is highly expressed in CD133+Exo compared to exosomes derived from endothelial cells. Compared to PBS treatment, CD133+Exo treatment significantly increases miR-126 expression in the heart and decreases its target gene expression such as Sprouty-related, EVH1 domain-containing protein 1 (Spred-1), vascular cell adhesion protein (VCAM), and monocyte chemoattractant protein 1 (MCP1) in the heart of T2DM-stroke mice. CD133+Exo treatment significantly improves cardiac function in T2DM-stroke mice. The cardio-protective effects of CD133+Exo in T2DM-stroke mice may be attributed at least in part to increasing miR-126 expression and decreasing its target protein expression in the heart, increased myocardial capillary density and decreased cardiac inflammatory factor expression.

The Role of microRNAs in the Development of Type 2 Diabetes Complications

MicroRNAs represent a class of small (19-25 nucleotides) single-strand pieces of RNA that are noncoding ones. They are synthesized by RNA polymerase II from transcripts that fold back on themselves. They mostly act as gene regulatory agents that pair with complementary sequences on mRNA and produce silencing complexes, which, in turn, suppress coding genes at a post-transcriptional level. There is now evidence that microRNAs may affect insulin secretion or insulin action, as they can alter pancreatic beta cells development, insulin production, as well as insulin signaling. Any molecular disorder that affects these pathways can deteriorate insulin resistance and lead to type 2 diabetes mellitus (T2DM) onset. Furthermore, the expression of several microRNAs is up- or down-regulated in the presence of diabetic microvascular complications (i.e., peripheral neuropathy, nephropathy, retinopathy, foot ulcers), as well as in patients with coronary heart disease, stroke, and peripheral artery disease. However, more evidence is needed, specifically regarding T2DM patients, to establish the use of such microRNAs as diagnostical biomarkers or therapeutic targets in daily practice.

Role of microRNA-126 in vascular cognitive impairment in mice

Vascular dementia (VaD) affects cognition and memory. MicroRNA-126 (miR-126) is an angiogenic microRNA that regulates vascular function. In this study, we employ a multiple microinfarction (MMI) model to induce VaD in mice, and investigate VaD-induced cognitive dysfunction, white matter (WM) damage, glymphatic dysfunction and the role of miR-126 in mediating these effects. Male six-to eight-months old C57/BL6 mice (WT) were subject to MMI model, and cerebral blood flow (CBF), vessel patency, glymphatic function, cognitive function, and serum miR-126 expression were measured. Mice were sacrificed at 28 days after MMI. To investigate the role of miR-126 in VaD, cognitive function, water channel integrity and glymphatic function were assessed in male, six-to eight months old conditional-knockout endothelial cell miR-126 (miR-126^EC-/-), and control (miR-126^fl/fl) mice. MMI in WT mice induces significant cognitive deficits, decreases CBF and vessel patency; evokes astrocytic and microglial activation, increases inflammation, axonal/WM damage; decreases synaptic plasticity and dendritic spine density, instigates water channel and glymphatic dysfunction, and decreases serum miR-126 expression. MiR-126^EC-/- mice exhibit significant cognitive impairment, decreased CBF, myelin density and axon density, increased inflammation, and significant water channel and glymphatic dysfunction compared to miR-126^fl/fl mice. Reduction of endothelial miR-126 expression may mediate cognitive impairment in MMI-induced VaD.

From Tumor Metastasis towards Cerebral Ischemia-Extracellular Vesicles as a General Concept of Intercellular Communication Processes

Extracellular vesicles (EVs) have been tremendous carriers in both experimental and translational science. These vesicles—formerly regarded as artifacts of in vitro research—have a heterogeneous population of vesicles derived from virtually all eukaryotic cells. EVs consist of a bilayer lipid structure with a diameter of about 30 to 1000 nm and have a characteristic protein and non-coding RNA content that make up different forms of EVs such as exosomes, microvesicles, and others. Despite recent progress in the EV field, which is known to serve as potential biomarkers and therapeutic tools under various pathological conditions, fundamental questions are yet to be answered. This short review focuses on recently reported data regarding EVs under pathological conditions with a particular emphasis on the role of EVs under such different conditions like tumor formation and cerebral ischemia. The review strives to point out general concepts of EV intercellular communication processes that might be vital to both diagnostic and therapeutic strategies in the long run.

Augmented Brain Infiltration and Activation of Leukocytes After Cerebral Ischemia in Type 2 Diabetic Mice

Background: Stroke patients with diabetes suffer from higher mortality rate and worsened neurological outcome. However, the responses of immune system to cerebral ischemia in the setting of diabetes remain poorly understood. Methods: In this study, we investigated the temporal profile of leukocyte mobilization and brain infiltration following distal middle cerebral artery occlusion (dMCAO) in db/db mouse model of type 2 diabetes (T2D) and its db/+ normoglycemic controls. Results: We found a significant increase of brain-infiltrating CD4⁺ T cell at day 3 after dMCAO, and a delayed and dramatic increase of brain-infiltrating neutrophils, CD4⁺ T cells, CD8⁺ T cells, and B cells at day 7 after dMCAO in db/db mice vs. db/+ controls. Leukocyte subsets in the circulation and spleen were also measured, however, there is no significant difference between non-diabetic and diabetic groups. Furthermore, we identified an increased expression of activation marker CD69 in brain-infiltrating neutrophils, CD4⁺ T and CD8⁺ T cells, and IFN-γ in brain-infiltrating CD4⁺ T cells in db/db mice at day 7 after dMCAO. Conclusions: These findings for the first time demonstrate that cerebral ischemia induces a delayed and sustained augmentation of brain infiltration and activation of neutrophils and lymphocytes in type 2 diabetic mice and these altered immune responses might contribute to the severer brain tissue damage and worse neurological outcomes of diabetes stroke, which warrants further investigation.

MiR-126 Mediates Brain Endothelial Cell Exosome Treatment-Induced Neurorestorative Effects After Stroke in Type 2 Diabetes Mellitus Mice

Background and Purpose- Stroke patients with type 2 diabetes mellitus (T2DM) exhibit increased vascular and white matter damage and have worse prognosis compared with nondiabetic stroke patients. We investigated the neurorestorative effects of exosomes derived from mouse brain endothelial cells (EC-Exo) as treatment for stroke in T2DM mice and investigated the role of miR-126 in mediating EC-Exo-derived therapeutic benefits in T2DM-stroke mice. Methods- Adult, male BKS.Cg-m+/+Lepr^db/J (T2DM) mice were subjected to photothrombotic stroke model. T2DM mice were intravenously injected at 3 days after stroke with (1) PBS; (2) liposome mimic (vehicle control, 3×10¹⁰); (3) EC-Exo (3×10¹⁰); (4) knockdown of miR-126 in EC-Exo (miR-126^-/- EC-Exo, 3×10¹⁰). Behavioral and cognitive tests were performed, and mice were sacrificed at 28 days after stroke. Results- Compared with non-DM stroke mice, T2DM-stroke mice exhibit significantly decreased serum and brain tissue miR-126 expression. Endothelial cells and EC-Exo contain high levels of miR-126 compared with other cell types or exosomes derived from other types of cells, respectively (smooth muscle cells, astrocytes, and marrow stromal cells). Compared with PBS or liposome mimic treatment, EC-Exo treatment of T2DM-stroke mice significantly improves neurological and cognitive function, increases axon density, myelin density, vascular density, arterial diameter, as well as induces M2 macrophage polarization in the ischemic boundary zone. MiR-126^-/- EC-Exo treatment significantly decreases miR-126 expression in serum and brain, as well as attentuates EC-Exo treatment-induced functional improvement and does not significantly increase axon and myelin density, vascular density, arterial diameter or induce M2 macrophage polarization in T2DM-stroke mice. In vitro, EC-Exo treatment significantly increases primary cortical neuron axonal outgrowth and increases endothelial capillary tube formation whereas miR-126^-/- EC-Exo attentuates EC-Exo induced capillary tube formation and axonal outgrowth. Conclusions- EC-Exo treatment of stroke promotes neurorestorative effects in T2DM mice. MiR-126 may mediate EC-Exo-induced neurorestorative effects in T2DM mice. Visual Overview- An online visual overview is available for this article.

Intravenous delivery of adipose tissue-derived mesenchymal stem cells improves brain repair in hyperglycemic stroke rats

Background

Over 50% of acute stroke patients have hyperglycemia, which is associated with a poorer prognosis and outcome. Our aim was to investigate the impact of hyperglycemia on behavioral recovery and brain repair of delivered human adipose tissue-derived mesenchymal stem cells (hAD-MSCs) in a rat model of permanent middle cerebral artery occlusion (pMCAO).

Methods

Hyperglycemia was induced in rats by the administration of nicotinamide and streptozotocin. The rats were then subjected to stroke by a pMCAO model. At 48 h post-stroke, 1 × 10⁶ hAD-MSCs or saline were intravenously administered. We evaluated behavioral outcome, infarct size by MRI, and brain plasticity markers by immunohistochemistry (glial fibrillary acidic protein [GFAP], Iba-1, synaptophysin, doublecortin, CD-31, collagen-IV, and α-smooth muscle actin [α-SMA]).

Results

The hyperglycemic group exhibited more severe neurological deficits; lesion size and diffusion coefficient were larger compared with the non-hyperglycemic rats. GFAP, Iba-1, and α-SMA were increased in the hyperglycemic group. The hyperglycemic rats administered hAD-MSCs at 48 h after pMCAO had improved neurological impairment. Although T2-MRI did not show differences in lesion size between groups, the rADC values were lower in the treated group. Finally, the levels of GFAP, Iba-1, and arterial wall thickness were lower in the treated hyperglycemic group than in the nontreated hyperglycemic group at 6 weeks post-stroke.

Conclusions

Our data suggest that rats with hyperglycemic ischemic stroke exhibit increased lesion size and impaired brain repair processes, which lead to impairments in behavioral recovery after pMCAO. More importantly, hAD-MSC administration induced better anatomical tissue preservation, associated with a good behavioral outcome.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1322-x) contains supplementary material, which is available to authorized users.

Placenta-Derived Cells for Acute Brain Injury

Acute brain injury resulting from ischemic/hemorrhagic or traumatic damage is one of the leading causes of mortality and disability worldwide and is a significant burden to society. Neuroprotective options to counteract brain damage are very limited in stroke and traumatic brain injury (TBI). Given the multifaceted nature of acute brain injury and damage progression, several therapeutic targets may need to be addressed simultaneously to interfere with the evolution of the injury and improve the patient’s outcome. Stem cells are ideal candidates since they act on various mechanisms of protection and repair, improving structural and functional outcomes after experimental stroke or TBI. Stem cells isolated from placenta offer advantages due to their early embryonic origin, ease of procurement, and ethical acceptance. We analyzed the evidence for the beneficial effects of placenta-derived stem cells in acute brain injury, with the focus on experimental studies of TBI and stroke, the engineering strategies pursued to foster cell potential, and characterization of the bioactive molecules secreted by placental cells, known as their secretome, as an alternative cell-free strategy. Results from the clinical application of placenta-derived stem cells for acute brain injury and ongoing clinical trials are summarily discussed.

Cytokine and microRNA levels during different periods of paradoxical sleep deprivation and sleep recovery in rats

Background

Sleep has a fundamental role in the regulation of homeostasis. The aim of this study was to assess the effect of different periods of paradoxical sleep deprivation (PSD) and recovery on serum levels of cytokines and miRNAs related to inflammatory responses.

Methods

Male Wistar rats were submitted to a PSD of 24, 96, or 192 h, or of 192 h followed by 20 days of recovery (192 h PSD+R). The concentrations of corticosterone, cytokines (IL-6, TNF, IL-10, Adiponectin) and miRNAs (miR-146a, miR-155, miR-223, miR-16, miR-126, miR-21) in serum were evaluated.

Results

At PSD 24 h a significant increase of IL-6 and decrease of IL-10 were observed. At PSD 96h adiponectin increased. At 192 h of PSD IL-6 increased significantly again, accompanied by a threefold increase of IL-10 and an increase of serum corticosterone. After 20 days of recovery (192 h PSD+R) corticosterone, IL-6 and TNF levels increased significantly, while IL-10 decreased also significantly. Regarding the miRNAs at 24 h of PSD serum miR-146a, miR-155, miR-223, and miR-16 levels all increased. At 96 h of PSD miR-223 decreased. At 192 h of PSD decreases in miR-16 and miR-126 were observed. After recovery serum miR-21 increased and miR-16 decreased.

Conclusion

PSD induces a dynamic response likely reflecting the induced cellular stress and manifested as variating hormonal and inflammatory responses. Sleep deprivation disturbed corticosterone, cytokine and miRNA levels in serum related to the duration of sleep deprivation, as short-term PSD produced effects similar to those of an acute inflammatory response and long-term PSD induced long-lasting disturbances of biological mediators.

Prophylactic Zinc and Therapeutic Selenium Administration Increases the Antioxidant Enzyme Activity in the Rat Temporoparietal Cortex and Improves Memory after a Transient Hypoxia-Ischemia

In the cerebral hypoxia-ischemia rat model, the prophylactic administration of zinc can cause either cytotoxicity or preconditioning effect, whereas the therapeutic administration of selenium decreases the ischemic damage. Herein, we aimed to explore whether supplementation of low doses of prophylactic zinc and therapeutic selenium could protect from a transient hypoxic-ischemic event. We administrated zinc (0.2 mg/kg of body weight; ip) daily for 14 days before a 10 min common carotid artery occlusion (CCAO). After CCAO, we administrated sodium selenite (6 μg/kg of body weight; ip) daily for 7 days. In the temporoparietal cerebral cortex, we determined nitrites by the Griess method and lipid peroxidation by the Gerard-Monnier assay. qPCR was used to measure mRNA of nitric oxide synthases, antioxidant enzymes, chemokines, and their receptors. We measured the enzymatic activity of SOD and GPx and protein levels of chemokines and their receptors by ELISA. We evaluated long-term memory using the Morris-Water maze test. Our results showed that prophylactic administration of zinc caused a preconditioning effect, decreasing nitrosative/oxidative stress and increasing GPx and SOD expression and activity, as well as eNOS expression. The therapeutic administration of selenium maintained this preconditioning effect up to the late phase of hypoxia-ischemia. Ccl2, Ccr2, Cxcl12, and Cxcr4 were upregulated, and long-term memory was improved. Pyknotic cells were decreased suggesting prevention of neuronal cell death. Our results show that the prophylactic zinc and therapeutic selenium administration induces effective neuroprotection in the early and late phases after CCAO.

Increased BBB Permeability Enhances Activation of Microglia and Exacerbates Loss of Dendritic Spines After Transient Global Cerebral Ischemia

Ischemic stroke can induce rapid disruption of blood-brain barrier (BBB). It has been suggested that increased BBB permeability can affect the pathological progression of ischemic tissue. However, the impact of increased BBB permeability on microglial activation and synaptic structures following reperfusion after ischemia remains unclear. In this study, we investigated microglial activation, dendritic damage and plasticity of dendritic spines after increasing BBB permeability following transient global cerebral ischemia in the somatosensory cortices in mice. Bilateral common carotid artery ligation (BCAL) was used to induce transient global cerebral ischemia. Mannitol was used to increase the BBB permeability. Intravital two-photon imaging was performed to image the dendritic structures and BBB extravasation. Microglial morphology was quantitated using a skeletonization analysis method. To evaluate inflammation of cerebral cortex, the mRNA expression levels of integrin alpha M (CD11b), CD68, chemokine (C-X-C motif) ligand 10 (IP10) and tumor necrosis factor alpha (TNF-α) were measured by fluorescent quantitative PCR. Intravital two-photon imaging revealed that mannitol caused a drastic increase in BBB extravasation during reperfusion after transient global ischemia. Increased BBB permeability induced by mannitol had no significant effect on inflammation and dendritic spines in healthy mice but triggered a marked de-ramification of microglia; importantly, in ischemic animals, mannitol accelerated de-ramification of microglia and aggravated inflammation at 3 h but not at 3 days following reperfusion after ischemia. Although mannitol did not cause significant change in the percentage of blebbed dendrites and did not affect the reversible recovery of the dendritic structures, excessive extravasation was accompanied with significant decrease in spine formation and increase in spine elimination during reperfusion in ischemic mice. These findings suggest that increased BBB permeability induced by mannitol can lead to acute activation of microglia and cause excessive loss of dendritic spines after transient global cerebral ischemia.

The therapeutic potential of the mesenchymal stem cell secretome in ischaemic stroke

Mesenchymal stem cells (MSCs) hold great potential as a regenerative therapy for stroke, leading to increased repair and functional recovery in animal models of cerebral ischaemia. While it was initially hypothesised that cell replacement was an important mechanism of action of MSCs, focus has shifted to their paracrine actions or the so called "bystander" effect. MSCs secrete a wide array of growth factors, chemokines, cytokines and extracellular vesicles, commonly referred to as the MSC secretome. There is evidence suggesting the MSC secretome can promote repair through a number of mechanisms including preventing cell apoptosis, modulating the inflammatory response and promoting endogenous repair mechanisms such as angiogenesis and neurogenesis. In this review, we will discuss the in vitro approaches currently being employed to drive the MSC secretome towards a more anti-inflammatory and regenerative phenotype. We will then examine the role of the secretome in promoting repair and improving recovery in preclinical models of cerebral ischaemia.

The Roles of MicroRNAs in Stroke: Possible Therapeutic Targets

Stroke is one of the most devastating diseases worldwide. In recent years, a great number of studies have focused on the effects of microRNAs (miRNAs) on stroke and the results demonstrated that the expressions of miRNAs are associated with the prognosis of stroke. In the present study, we review relevant articles regarding miRNAs and stroke and will explain the complex link between both. The miRNAs participate extensively in the pathophysiology following the stroke, including apoptosis, neuroinflammation, oxidative stress, blood–brain barrier (BBB) disruption and brain edema. The information about the stroke–miRNA system may be helpful for therapeutic and diagnostic methods in stroke treatment.

APX3330 Promotes Neurorestorative Effects after Stroke in Type One Diabetic Rats

APX3330 is a selective inhibitor of APE1/Ref-1 redox activity. In this study, we investigate the therapeutic effects and underlying mechanisms of APX3330 treatment in type one diabetes mellitus (T1DM) stroke rats. Adult male Wistar rats were induced with T1DM and subjected to transient middle cerebral artery occlusion (MCAo) and treated with either PBS or APX3330 (10mg/kg, oral gavage) starting at 24h after MCAo, and daily for 14 days. Rats were sacrificed at 14 days after MCAo and, blood brain barrier (BBB) permeability, ischemic lesion volume, immunohistochemistry, cell death assay, Western blot, real time PCR, and angiogenic ELISA array were performed. Compared to PBS treatment, APX3330 treatment of stroke in T1DM rats significantly improves neurological functional outcome, decreases lesion volume, and improves BBB integrity as well as decreases total vessel density and VEGF expression, while significantly increases arterial density in the ischemic border zone (IBZ). APX3330 significantly increases myelin density, oligodendrocyte number, oligodendrocyte progenitor cell number, synaptic protein expression, and induces M2 macrophage polarization in the IBZ of T1DM stroke rats. Compared to PBS treatment, APX3330 treatment significantly decreases plasminogen activator inhibitor type-1 (PAI-1), monocyte chemotactic protein-1 and matrix metalloproteinase 9 (MMP9) and receptor for advanced glycation endproducts expression in the ischemic brain of T1DM stroke rats. APX3330 treatment significantly decreases cell death and MMP9 and PAI-1 gene expression in cultured primary cortical neurons subjected to high glucose and oxygen glucose deprivation, compared to untreated control cells. APX3330 treatment increases M2 macrophage polarization and decreases inflammatory factor expression in the ischemic brain as well as promotes neuroprotective and neurorestorative effects after stroke in T1DM rats.

Cell-Based and Exosome Therapy in Diabetic Stroke

Stroke is a global health concern and it is imperative that therapeutic strategies with wide treatment time frames be developed to improve neurological outcome in patients. Patients with diabetes mellitus who suffer a stroke have worse neurological outcomes and long‐term functional recovery than nondiabetic stroke patients. Diabetes induced vascular damage and enhanced inflammatory milieu likely contributes to worse post stroke outcomes. Diabetic stroke patients have an aggravated pathological cascade, and treatments that benefit nondiabetic stroke patients do not necessarily translate to diabetic stroke patients. Therefore, there is a critical need to develop therapeutics for stroke specifically in the diabetic population. Stem cell based therapy for stroke is an emerging treatment option with wide therapeutic time window. Cell‐based therapies for stroke promote endogenous central nervous system repair and neurorestorative mechanisms such as angiogenesis, neurogenesis, vascular remodeling, white matter remodeling, and also modulate inflammatory and immune responses at the local and systemic level. Emerging evidence suggests that exosomes and their cargo microRNA mediate cell therapy derived neurorestorative effects. Exosomes are small vesicles containing protein and RNA characteristic of its parent cell. Exosomes are transported by biological fluids and facilitate communication between neighboring and remote cells. MicroRNAs, a class of naturally occurring, small noncoding RNA sequences, contained within exosomes can regulate recipient cell's signaling pathways and alter protein expression either acting alone or in concert with other microRNAs. In this perspective article, we summarize current knowledge and highlight the promising future of cell based and exosome therapy for stroke and specifically for diabetic stroke. stemcellstranslationalmedicine2018;7:451–455

miR-330-5p/Tim-3 axis regulates macrophage M2 polarization and insulin resistance in diabetes mice

Obesity is associated with a state of low-grade inflammatory response in adipose tissue, and contributes to the development of type 2 diabetes. Immune cells such as macrophages can infiltrate adipose tissue and are responsible for the majority of inflammatory cytokine production. Therefore, adipose tissue promotes macrophage infiltration, resulting in local inflammation and insulin resistance. Tim-3 negatively regulates IFN-γ secretion and influences the ability to induce T cell tolerance in diabetes. MicroRNA contributes to the development of immunological tolerance and involves in macrophage polarization. However, the potential of Tim-3 to regulate macrophage polarization and the related microRNA has not been reported. In this experiment, 8-week-old C57BL/6 mice were fed a high-fat diet for 8 weeks. The adipose tissue macrophages were isolated, miR-330-5p and Tim-3 levels, and M1/M2 polarization were analyzed. In addition, insulin tolerance tests was detected. The results demonstrated that miR-330-5p levels increased but Tim-3 levels decreased, leading to M1 polarization and insulin tolerance in diabetes mice. In addition, inhibition of miR-330-5p enhanced Tim-3 levels, leading to M2 polarization and insulin tolerance attenuation in diabetes mice. Furthermore, we detected the inverse relationship between miR-330-5p and Tim-3. We found that Tim-3 mRNA contained conserved miR-330-5p binding sites in its 3'UTR, and miR-330-5p could directly regulate Tim-3 expression through these 3'UTR sites. Our study demonstrated that miR-330-5p served as a regulator of the M2 polarization and miR-330-5p/Tim-3 axis potentially down-regulated insulin resistance in diabetes, probably through enhancing the M2 polarization of macrophage.

Cell-based and pharmacological neurorestorative therapies for ischemic stroke

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

MicroRNA-126 Regulates Inflammatory Cytokine Secretion in Human Gingival Fibroblasts Under High Glucose via Targeting Tumor Necrosis Factor Receptor Associated Factor 6

BACKGROUND

MicroRNAs (miRs) play a crucial role in inflammatory diseases, including periodontitis. Meanwhile, miRs act as biomarkers for predicting diabetes mellitus (DM). However, the regulatory mechanism of miR-126 on development of periodontitis in patients with DM still remains unclear.

METHODS

Human gingival fibroblasts were cultured with low (5.5 mmol/L), medium (15 mmol/L), and high (25 mmol/L) glucose, respectively. Expressions of miR-126, tumor necrosis factor (TNF) receptor associated factor (TRAF) 6, and related cytokines were analyzed by real-time polymerase chain reaction (PCR). After transfection with miR-126 mimic, PCR and western blot were performed to detect level of TRAF6, and luciferase reporter assay confirmed if TRAF6 is the direct target of miR-126. Production of cytokines was measured using enzyme-linked immunosorbent assay.

RESULTS

Increased glucose significantly suppressed miR-126 expression in human gingival fibroblasts (P <0.05). Also, high glucose increased TRAF6, interleukin (IL)-6, TNF-α, and chemical chemokine ligand (CCL) 2 levels, whereas it decreased IL-10 level. MiR-126 mimic significantly decreased TRAF6 mRNA and protein levels under high glucose (P <0.05). Also, miR-126 directly targeted TRAF6 through binding to its 3' untranslated region in human gingival fibroblasts. Overexpression of miR-126 significantly abrogated high glucose-induced secretion of proinflammatory cytokines such as IL-6, TNF-α, and CCL2 and promoted production of IL-10.

CONCLUSION

These data suggest that miR-126 inhibits inflammation of human gingival fibroblasts under high glucose through targeting TRAF6, which may be a potential therapeutic target for periodontitis concomitant with DM.

MiR-126 and miR-126* regulate shear-resistant firm leukocyte adhesion to human brain endothelium

Leukocyte adhesion to brain endothelial cells, the blood-brain barrier main component, is a critical step in the pathogenesis of neuroinflammatory diseases such as multiple sclerosis (MS). Leukocyte adhesion is mediated mainly by selectins, cell adhesion molecules and chemokines induced by pro-inflammatory cytokines such as TNFα and IFNγ, but the regulation of this process is not fully clear. This study investigated the regulation of firm leukocyte adhesion to human brain endothelium by two different brain endothelial microRNAs (miRs), miR-126 and miR-126*, that are downregulated by TNFα and IFNγ in a human brain endothelial cell line, hCMEC/D3. Using a leukocyte adhesion in vitro assay under shear forces mimicking blood flow, we observed that reduction of endothelial miR-126 and miR-126* enhanced firm monocyte and T cell adhesion to hCMEC/D3 cells, whereas their increased expression partially prevented THP1, Jurkat and primary MS patient-derived PBMC firm adhesion. Furthermore, we observed that miR-126* and miR-126 downregulation increased E-selectin and VCAM1, respectively, while miR-126 overexpression reduced VCAM1 and CCL2 expression by hCMEC/D3 cells, suggesting that these miRs regulate leukocyte adhesion by modulating the expression of adhesion-associated endothelial mRNA targets. Hence, human brain endothelial miR-126 and miR-126* could be used as a therapeutic tool to reduce leukocyte adhesion and thus reduce neuroinflammation.

MiR-126 Affects Brain-Heart Interaction after Cerebral Ischemic Stroke

Cardiovascular diseases are approximately three times higher in patients with neurological deficits than in patients without neurological deficits. MicroRNA-126 (MiR-126) facilitates vascular remodeling and decreases fibrosis and is emerging as an important factor in the pathogenesis of cardiovascular diseases and cerebral stroke. In this study, we tested the hypothesis that decreased miR-126 after ischemic stroke may play an important role in regulating cardiac function. Wild-type (WT), specific conditional-knockout endothelial cell miR-126 (miR-126^EC-/-), and miR-126 knockout control (miR-126^fl/fl) mice were subjected to distal middle cerebral artery occlusion (dMCAo) (n = 10/group). Cardiac hemodynamics and function were measured using transthoracic Doppler echocardiography. Mice were sacrificed at 28 days after dMCAo. WT mice subjected to stroke exhibited significantly decreased cardiac ejection fraction and increased myocyte hypertrophy, fibrosis as well as increased heart inflammation, infiltrating macrophages, and oxidative stress compared to non-stroke animals. Stroke significantly decreased serum and heart miR-126 expression and increased miR-126 target genes, vascular cell adhesion protein-1, and monocyte chemotactic protein-1 gene, and protein expression in the heart compared to non-stroke mice. MiR-126^EC-/- mice exhibited significantly decreased cardiac function and increased cardiomyocyte hypertrophy, fibrosis, and inflammatory factor expression after stroke compared to miR-126^fl/fl stroke mice. Exosomes derived from endothelial cells of miR-126^EC-/- (miR-126^EC-/-EC-Exo) mice exhibited significantly decreased miR-126 expression than exosomes derived from miR-126^fl/fl (miR-126^fl/fl-EC-Exo) mice. Treatment of cardiomyocytes subjected to oxygen glucose deprivation with miR-126^fl/fl-EC-Exo exhibited significantly decreased hypertrophy than with miR-126^EC-/-EC-Exo treatment. Ischemic stroke directly induces cardiac dysfunction. Decreasing miR-126 expression may contribute to cardiac dysfunction after stroke in mice.

Immunomodulators and microRNAs as neurorestorative therapy for ischemic stroke

Most of all strokes are ischemic due to occlusion of a vessel, and comprise two main types, thrombotic and embolic. Inflammation and immune response play an important role in the outcome of ischemic stroke. Pharmaceutical and cell-based therapies with immunomodulatory properties could be of benefit in treating ischemic stroke. Possible changes in microRNAs brought about by immunomodulatory treatments may be important. The pharmaceutical studies described in this review have identified several differentially regulated miRNAs associated with disregulation of mRNA targets or the upregulation of several neuroprotective genes, thereby highlighting the potential neuroprotective roles of specific miRNAs such as miR-762, -1892, -200a, -145. MiR-124, -711, -145 are the strongly associated miRNAs predicted to mediate anti-inflammatory pathways and microglia/macrophage M2-like activation phenotype. The cell-based therapy studies reviewed have mainly utilized mesenchymal stem cells or human umbilical cord blood cells and shown to improve functional and neurological outcomes in stroke animals. MiR-145 and miR-133b were implicated in nerve cell remodeling and functional recovery after stroke. Human umbilical cord blood cells decreased proinflammatory factors and promoted M2 macrophage polarization in stroke diabetic animals.

White matter damage and glymphatic dysfunction in a model of vascular dementia in rats with no prior vascular pathologies

We investigated cognitive function, axonal/white matter (WM) changes and glymphatic function of vascular dementia using a multiple microinfarction (MMI) model in retired breeder (RB) rats. The MMI model induces significant (p < 0.05) cognitive decline that worsens with age starting at 2 weeks, which persists until at least 6 weeks after MMI. RB rats subjected to MMI exhibit significant axonal/WM damage identified by decreased myelin thickness, oligodendrocyte progenitor cell numbers, axon density, synaptic protein expression in the cortex and striatum, cortical neuronal branching, and dendritic spine density in the cortex and hippocampus compared with age-matched controls. MMI evokes significant dilation of perivascular spaces as well as water channel dysfunction indicated by decreased Aquaporin-4 expression around blood vessels. MMI-induced glymphatic dysfunction with delayed cerebrospinal fluid penetration into the brain parenchyma via paravascular pathways as well as delayed waste clearance from the brain. The MMI model in RB rats decreases Aquaporin-4 and induces glymphatic dysfunction which may play an important role in MMI-induced axonal/WM damage and cognitive deficits.