Endothelial progenitor cells: Potential novel therapeutics for ischaemic stroke

T cell interactions with microglia in immune-inflammatory processes of ischemic stroke

The primary mechanism of secondary injury after cerebral ischemia may be the brain inflammation that emerges after an ischemic stroke, which promotes neuronal death and inhibits nerve tissue regeneration. As the first immune cells to be activated after an ischemic stroke, microglia play an important immunomodulatory role in the progression of the condition. After an ischemic stroke, peripheral blood immune cells (mainly T cells) are recruited to the central nervous system by chemokines secreted by immune cells in the brain, where they interact with central nervous system cells (mainly microglia) to trigger a secondary neuroimmune response. This review summarizes the interactions between T cells and microglia in the immune-inflammatory processes of ischemic stroke. We found that, during ischemic stroke, T cells and microglia demonstrate a more pronounced synergistic effect. Th1, Th17, and M1 microglia can co-secrete pro-inflammatory factors, such as interferon-γ, tumor necrosis factor-α, and interleukin-1β, to promote neuroinflammation and exacerbate brain injury. Th2, Treg, and M2 microglia jointly secrete anti-inflammatory factors, such as interleukin-4, interleukin-10, and transforming growth factor-β, to inhibit the progression of neuroinflammation, as well as growth factors such as brain-derived neurotrophic factor to promote nerve regeneration and repair brain injury. Immune interactions between microglia and T cells influence the direction of the subsequent neuroinflammation, which in turn determines the prognosis of ischemic stroke patients. Clinical trials have been conducted on the ways to modulate the interactions between T cells and microglia toward anti-inflammatory communication using the immunosuppressant fingolimod or overdosing with Treg cells to promote neural tissue repair and reduce the damage caused by ischemic stroke. However, such studies have been relatively infrequent, and clinical experience is still insufficient. In summary, in ischemic stroke, T cell subsets and activated microglia act synergistically to regulate inflammatory progression, mainly by secreting inflammatory factors. In the future, a key research direction for ischemic stroke treatment could be rooted in the enhancement of anti-inflammatory factor secretion by promoting the generation of Th2 and Treg cells, along with the activation of M2-type microglia. These approaches may alleviate neuroinflammation and facilitate the repair of neural tissues.

The Impact of Folic Acid Deficiency on Ischemic Stroke: Role of Inflammation and Long Noncoding RNA H19

It has been validated that folic acid deficiency (FD) is associated with an increased risk of stroke and a worse prognosis. However, the specific mechanisms by which FD exerts its detrimental effects on ischemic stroke (IS) have not been fully understood. The results of this case-control study indicated that patients with IS had a decreased serum folate level, along with up-regulated long non-coding RNA H19 (lncRNA H19) and enhanced inflammatory responses. Meanwhile, it was corroborated that the serum folate level was negatively correlated with H19 expression and the systemic immune-inflammation index (SII). Similarly, FD was demonstrated to exacerbate neurological injury in the middle cerebral artery occlusion/reperfusion (MCAO/R) rats by up-regulating the expression of inflammatory cytokines and H19 in both peripheral blood and brain tissue. Notably, the alterations in the expression of these factors in peripheral blood were consistent with those observed in brain tissue. Additionally, in a co-culture of N2a neurons and BV2 microglia, FD promoted the transition of BV2 cells towards a pro-inflammatory state by up-regulating the expression of H19, which aggravated neuronal injury. Moreover, blocking H19 in BV2 cells mitigated inflammation and partially reversed the injury in N2a cells exacerbated by FD after the treatment with oxygen-glucose deprivation and reperfusion (OGD/R). These findings provide a more in-depth insight into the regulatory role of H19-mediated systemic inflammatory responses in the context of FD, suggesting the potential clinical utility of folic acid in managing ischemic brain injury.

Hyperglycaemia perturbs blood-brain barrier integrity through its effects on endothelial cell characteristics and function

Breakdown of blood-brain barrier (BBB) represents a key pathology in hyperglycemia-mediated cerebrovascular damage after an ischemic stroke. As changes in the level and nature of vasoactive agents released by endothelial cells (ECs) may contribute to BBB dysfunction, this study first explored the specific impact of hyperglycemia on EC characteristics and secretome. It then assessed whether secretome obtained from ECs subjected to normoglycaemia or hyperglycemia might regulate pericytic cytokine profile differently. Using a triple cell culture model of human BBB, composed of brain microvascular EC (BMEC), astrocytes and pericytes, this study showed that exposure to hyperglycemia (25 mM D-glucose) for 72 h impaired the BBB integrity and function as evidenced by decreases in transendothelial electrical resistance and increases in paracellular flux of sodium fluorescein. Dissolution of zonula occludens-1, a tight junction protein, and appearance of stress fibers appeared to play a key role in this pathology. Despite elevations in angiogenin, endothelin-1, interleukin-8 and basic fibroblast growth factor levels and a decrease in placental growth factor levels in BMEC subjected to hyperglycemia vs normoglycaemia (5.5 mM D-glucose), tubulogenic capacity of BMECs remained similar in both settings. Similarly, pericytes subjected to secretome obtained from hyperglycemic BMEC released higher quantities of macrophage migration inhibitory factor and serpin and lower quantities of monocyte chemoattractant protein-1, intercellular adhesion molecule, interleukin-6 and interleukin-8. Taken together these findings indicate the complexity of the mechanisms leading to BBB disruption in hyperglycemic settings and emphasize the importance of endothelial cell-pericyte axis in the development of novel therapeutic strategies.

Mechanism of inflammatory response and therapeutic effects of stem cells in ischemic stroke: current evidence and future perspectives

Ischemic stroke is a leading cause of death and disability worldwide, with an increasing trend and tendency for onset at a younger age. China, in particular, bears a high burden of stroke cases. In recent years, the inflammatory response after stroke has become a research hotspot: understanding the role of inflammatory response in tissue damage and repair following ischemic stroke is an important direction for its treatment. This review summarizes several major cells involved in the inflammatory response following ischemic stroke, including microglia, neutrophils, monocytes, lymphocytes, and astrocytes. Additionally, we have also highlighted the recent progress in various treatments for ischemic stroke, particularly in the field of stem cell therapy. Overall, understanding the complex interactions between inflammation and ischemic stroke can provide valuable insights for developing treatment strategies and improving patient outcomes. Stem cell therapy may potentially become an important component of ischemic stroke treatment.

The therapeutic effects of salvianolic acids on ischemic stroke: From molecular mechanisms to clinical applications

Ischemic stroke (IS), primarily caused by cerebrovascular occlusion, poses a significant public health challenge with limited effective therapeutic options. Evidence suggests that salvianolic acids (SAs), mainly from Salvia miltiorrhiza Bunge, have been formulated into injections and are widely used in clinical treatments for cardiovascular and cerebrovascular diseases, including stroke. The pharmacological properties of SAs include reducing neuroinflammation, alleviating oxidative stress injury, inhibiting cellular apoptosis, preserving endothelial function, maintaining blood-brain barrier integrity, and promoting angiogenesis. Salvianolic acids for injection (SAFI) serve as a safe and effective treatment option for cardiovascular and cerebrovascular conditions by influencing various signaling pathways and molecular targets associated with these diseases. In this review, we first discuss the pathogenesis of IS, then summarize the classification of SAs, elaborate detailed molecular mechanisms of their efficacy, and the related clinical applications of SAFI. We also emphasize the recent pharmacological advancements and therapeutic possibilities of this promising drug preparation derived from herbs for cerebrovascular conditions.

The impact of acute and chronic aerobic and resistance exercise on stem cell mobilization: A review of effects in healthy and diseased individuals across different age groups

Stem cells (SCs) play a crucial role in tissue repair, regeneration, and maintaining physiological homeostasis. Exercise mobilizes and enhances the function of SCs. This review examines the effects of acute and chronic aerobic and resistance exercise on the population of SCs in healthy and diseased individuals across different age groups. Both acute intense exercise and moderate regular training increase circulating precursor cells CD34+ and, in particular, the subset of angiogenic progenitor cells (APCs) CD34+/KDR+. Conversely, chronic exercise training has conflicting effects on circulating CD34+ cells and their function, which are likely influenced by exercise dosage, the health status of the participants, and the methodologies employed. While acute activity promotes transient mobilization, regular exercise often leads to an increased number of progenitors and more sustainable functionality. Short interventions lasting 10-21 days mobilize CD34+/KDR + APCs in sedentary elderly individuals, indicating the inherent capacity of the body to rapidly activate tissue-reparative SCs during activity. However, further investigation is needed to determine the optimal exercise regimens for enhancing SC mobilization, elucidating the underlying mechanisms, and establishing functional benefits for health and disease prevention. Current evidence supports the integration of intense exercise with chronic training in exercise protocols aimed at activating the inherent regenerative potential through SC mobilization. The physical activity promotes endogenous repair processes, and research on exercise protocols that effectively mobilize SCs can provide innovative guidelines designed for lifelong tissue regeneration. An artificial neural network (ANN) was developed to estimate the effects of modifying elderly individuals and implementing chronic resistance exercise on stem cell mobilization and its impact on individuals and exercise. The network's predictions were validated using linear regression and found to be acceptable compared to experimental results.

Targeting the neurovascular unit: Therapeutic potential of traditional Chinese medicine for the treatment of stroke

Stroke poses a significant global health challenge due to its elevated disability and mortality rates, particularly affecting developing nations like China. The neurovascular unit (NVU), a new concept encompassing neurons, brain microvascular endothelial cells, pericytes, astrocytes, microglia, and the extracellular matrix, has gained prominence in recent years. Traditional Chinese medicine (TCM), deeply rooted in Chinese history, employs a combination of acupuncture and herbal treatments, demonstrating significant efficacy across all stages of stroke, notably during recovery. The holistic approach of TCM aligns with the NVU's comprehensive view of treating stroke by addressing neurons, surrounding cells, and blood vessels collectively. This review examines the role of NVU in stroke and endeavors to elucidate the mechanisms through which traditional Chinese medicine exerts its anti-stroke effects within the NVU framework. The NVU contributes to neuroinflammation, immune infiltration, blood-brain barrier permeability, oxidative stress, and Ca2+ overload during stroke occurs. Additionally, TCM targeting the NVU facilitates nerve repair post-stroke through various pathways and approaches. Specific herbs, including panax notoginseng, ginseng, and borneol, alleviate brain injury by enhancing brain-derived neurotrophic factor expression and targeting astrocytes and microglia to yield anti-inflammatory and antioxidant effects. Acupuncture, another facet of TCM, promotes brain injury repair by augmenting cerebral blood flow and improving circulation. This exploration aims to assess the viability of stroke treatment by directing TCM interventions toward the NVU, thus paving the way for its broader clinical application.

Tilianin attenuates inflammasome activation in endothelial progenitor cells to mitigate myocardial ischemia-reperfusion injury

Tilianin (TIL), a bioactive component derived from Dracocephalum Moldavica L., has been recognized for its anti-inflammatory properties. However, its effects on the Nlrp3 inflammasome within endothelial progenitor cells (EPCs) during myocardial ischemia-reperfusion injury (MIRI) remain unexplored. This study aimed to elucidate the role of TIL in modulating Nlrp3 inflammasome activation under MIRI conditions. A mouse model of MIRI was established to assess the therapeutic potential of TIL. EPCs treated with TIL at concentrations of 5, 10, and 20 μM were administered into the myocardium before reperfusion. Additionally, the cardioprotective effects of TIL were further examined by pre-treating EPCs with the compound before exposing them to hypoxia/reoxygenation (H/R) using cardiomyocyte supernatants. The impact on Nlrp3 inflammasome was assessed through western blotting, immunofluorescence, and ELISA. Our results showed that TIL concentration-dependently inhibited Nlrp3 inflammasome-related protein levels,and inhibited Asc oligomerization and Asc-Speck complex formation in EPCs, resulting in improved the migratory capacity and vascular structure formation of EPCs. In addition, TIL-treated EPCs significantly attenuated I/R injury and improved cardiac function. These results suggest that TIL ameliorates the inflammatory response in EPCs by suppressing Nlrp3 inflammasome activation, thereby facilitating neovascularization in the myocardium and conferring protection against MIRI. The study provides valuable insights into the potential of TIL as a therapeutic agent for cardiovascular diseases linked to ischemia-reperfusion injury.

Exploration of the mechanism of Taohong Siwu Decoction for the treatment of ischemic stroke based on CCL2/CCR2 axis

Background and aims

Taohong Siwu Decoction (THSWD) is a traditional Chinese herbal prescription that is effective for ischemic stroke, Whether THSWD regulates the CCL2/CCR2 axis and thus reduces the inflammatory response induced by ischemic stroke is not known. The aim of this study was to elucidate the mechanism of action of THSWD in the treatment of ischemic stroke using bioinformatics combined with in vitro and in vivo experiments.

Methods

R language was used to analyze middle cerebral artery occlusion/reperfusion (MCAO/R) rat transcriptome data and to identify differential gene expression following THSWD treatment. Gene set enrichment analysis (GSEA) was used to analyze the gene set enrichment pathway of MCAO/R rats treated with THSWD. PPI networks screened key targets. The Human Brain Microvascular Endothelial Cells (HBMEC) Oxygen Glucose Deprivation/Reoxygenation (OGD/R) model and SD rat models of MCAO/R were established. FITC-dextran, immunofluorescence, flow cytometry, ELISA, immunohistochemistry, Western blotting, and RT-qPCR were performed to identify potential treatment targets.

Results

A total of 515 differentially expressed genes of THSWD in MCAO/R rats were screened and 92 differentially expressed genes of THSWD potentially involved in stroke intervention were identified, including Cd68, Ccl2, and other key genes. In vitro, THSWD reversed the increase in permeability of HBMEC cells and M1/M2 polarization of macrophages induced by CCL2/CCR2 axis agonists. In vivo, THSWD improved nerve function injury and blood-brain barrier injury in MCAO/R rats. Further, THSWD inhibited the infiltration and polarization of macrophages, reduced the expression of IL-6, TNF-α, and MMP-9, and increased the expression of IL-4, while reducing the gene and protein expression of CCL2 and CCR2.

Conclusion

THSWD may play a protective role in ischemic stroke by inhibiting the CCL2/CCR2 axis, reducing the infiltration of macrophages, and promoting the polarization of M2 macrophages, thereby reducing inflammatory damage, and protecting injury to the blood-brain barrier.

Endothelial progenitor cells control remodeling of uterine spiral arteries for the establishment of utero-placental circulation

Placental ischemia, resulting from inadequate remodeling of uterine spiral arteries, is a factor in the development of preeclampsia. However, the effect of endothelial progenitor cells that play a role in the vascular injury-repair program is largely unexplored during remodeling. Here, we observe that preeclampsia-afflicted uterine spiral arteries transition to a synthetic phenotype in vascular smooth muscle cells and characterize the regulatory axis in endothelial progenitor cells during remodeling in human decidua basalis. Excessive sEng, secreted by AMP-activated protein kinase (AMPK)-deficient endothelial progenitor cells through the inhibition of HO-1, damages residual endothelium and leads to the accumulation of extracellular matrix produced by vascular smooth muscle cells during remodeling, which is further confirmed by animal models. Collectively, our findings suggest that the impaired functionality of endothelial progenitor cells contributes to the narrowing of remodeled uterine spiral arteries, leading to reduced utero-placental perfusion. This mechanism holds promise in elucidating the pathogenesis of preeclampsia.

Potential diagnostic biomarkers for immunogenic cell death in elderly female patients with ischemic stroke: identification and analysis

Ischemic stroke (IS) is of increasing concern given the aging population and prevalence of unhealthy lifestyles, with older females exhibiting higher susceptibility. This study aimed to identify practical diagnostic markers, develop a diagnostic model for immunogenic cell death (ICD)-associated IS, and investigate alterations in the immune environment caused by hub genes. Differentially expressed genes associated with ICD in IS were identified based on weighted gene co-expression network analysis and the identification of significant modules. Subsequently, machine learning algorithms were employed to screened hub genes, which were further assessed using Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and Gene Set Enrichment Analysis. A nomogram mode lwas then constructed for IS diagnosis, and its diagnostic value was assessed using a receiver operating characteristic curve. Finally, alterations in immune cell infiltration were assessed within patients with IS, and the pan-cancer expression patterns of hub genes were evaluated. Three hub genes associated with ICD (PDK4, CCL20, and FBL) were identified. The corresponding nomogram model for IS diagnosis could effectively identify older female patients with IS (area under the curve (AUC) = 0.9555). Overall, the three hub genes exhibit good diagnostic value (AUC > 0.8). CCL20 and FBL are significantly associated with the extent of immune cells infiltration. Moreover, a strong link exists between hub gene expression and pan-cancer prognosis. Cumulatively, these results indicate that ICD-related hub genes critically influence IS progression in older females, presenting novel diagnostic and therapeutic targets for personalized treatment.

γH2AX in mouse embryonic stem cells: Distribution during differentiation and following γ-irradiation

Phosphorylated histone H2AX (γH2AX) represents a sensitive molecular marker of DNA double-strand breaks (DSBs) and is implicated in stem cell biology. We established a model of mouse embryonic stem cell (mESC) differentiation and examined the dynamics of γH2AX foci during the process. Our results revealed high numbers of γH2AX foci in undifferentiated mESCs, decreasing as the cells differentiated towards the endothelial cell lineage. Notably, we observed two distinct patterns of γH2AX foci: the typical discrete γH2AX foci, which colocalize with the transcriptionally permissive chromatin mark H3K4me3, and the less well-characterized clustered γH2AX regions, which were only observed in intermediate progenitor cells. Next, we explored responses of mESCs to γ-radiation (137Cs). Following exposure to γ-radiation, mESCs showed a reduction in cell viability and increased γH2AX foci, indicative of radiosensitivity. Despite irradiation, surviving mESCs retained their differentiation potential. To further exemplify our findings, we investigated neural stem progenitor cells (NSPCs). Similar to mESCs, NSPCs displayed clustered γH2AX foci associated with progenitor cells and discrete γH2AX foci indicative of embryonic stem cells or differentiated cells. In conclusion, our findings demonstrate that γH2AX serves as a versatile marker of DSBs and may have a role as a biomarker in stem cell differentiation. The distinct patterns of γH2AX foci in differentiating mESCs and NSPCs provide valuable insights into DNA repair dynamics during differentiation, shedding light on the intricate balance between genomic integrity and cellular plasticity in stem cells. Finally, the clustered γH2AX foci observed in intermediate progenitor cells is an intriguing feature, requiring further exploration.

Ginseng-Sanqi-Chuanxiong (GSC) extracts attenuate d-galactose-induced vascular aging in mice via inhibition of endothelial progenitor cells senescence

Vascular aging is an independent risk factor for age-related diseases and a specific type of organic aging. Endothelial progenitor cells (EPCs), a type of bone marrow stem cell, has been linked to vascular aging. The purpose of this study is to investigate if Ginseng-Sanqi-Chuanxiong (GSC) extract, a traditional Chinese medicine, can delay aortic aging in mice by enhancing the performance and aging of EPCs in vivo and to analyze the potential mechanisms through a d-Galactose (D-gal)-induced vascular aging model in mice. Our study revealed that GSC extracts not only enhanced the aortic structure, endothelial function, oxidative stress levels, and aging in mice, but also enhanced the proliferation, migration, adhesion, and secretion of EPCs in vivo, while reducing the expression of p53, p21, and p16. To conclude, GSC can delay vascular senescence by enhancing the function and aging of EPCs, which could be linked to a decrease in p16 and p53/p21 signaling. Consequently, utilizing GSC extracts to enhance the function and senescence of autologous EPCs may present a novel avenue for enhancing autologous stem cells in alleviating senescence.

The Role of Stem Cells as Therapeutics for Ischaemic Stroke

Stroke remains one of the leading causes of death and disability worldwide. Current reperfusion treatments for ischaemic stroke are limited due to their narrow therapeutic window in rescuing ischaemic penumbra. Stem cell therapy offers a promising alternative. As a regenerative medicine, stem cells offer a wider range of treatment strategies, including long-term intervention for chronic patients, through the reparation and replacement of injured cells via mechanisms of differentiation and proliferation. The purpose of this review is to evaluate the therapeutic role of stem cells for ischaemic stroke. This paper discusses the pathology during acute, subacute, and chronic phases of cerebral ischaemic injury, highlights the mechanisms involved in mesenchymal, endothelial, haematopoietic, and neural stem cell-mediated cerebrovascular regeneration, and evaluates the pre-clinical and clinical data concerning the safety and efficacy of stem cell-based treatments. The treatment of stroke patients with different types of stem cells appears to be safe and efficacious even at relatively higher concentrations irrespective of the route and timing of administration. The priming or pre-conditioning of cells prior to administration appears to help augment their therapeutic impact. However, larger patient cohorts and later-phase trials are required to consolidate these findings.

Recent advances in tissue repair of the blood-brain barrier after stroke

The selective permeability of the blood-brain barrier (BBB) enables the necessary exchange of substances between the brain parenchyma and circulating blood and is important for the normal functioning of the central nervous system. Ischemic stroke inflicts damage upon the BBB, triggering adverse stroke outcomes such as cerebral edema, hemorrhagic transformation, and aggravated neuroinflammation. Therefore, effective repair of the damaged BBB after stroke and neovascularization that allows for the unique selective transfer of substances from the BBB after stroke is necessary and important for the recovery of brain function. This review focuses on four important therapies that have effects of BBB tissue repair after stroke in the last seven years. Most of these new therapies show increased expression of BBB tight-junction proteins, and some show beneficial results in terms of enhanced pericyte coverage at the injured vessels. This review also briefly outlines three effective classes of approaches and their mechanisms for promoting neoangiogenesis following a stroke.

Analysis of endothelial progenitor cell subtypes as clinical biomarkers for elderly patients with ischaemic stroke

Endothelial progenitor cells (EPCs), expressing markers for stemness (CD34), immaturity (CD133) and endothelial maturity (KDR), may determine the extent of post-stroke vascular repair. Given the prevalence of stroke in elderly, this study explored whether variations in plasmatic availability of certain EPC subtypes could predict the severity and outcome of disease in older patients. Blood samples were collected from eighty-one consented patients (≥ 65 years) at admission and days 7, 30 and 90 post-stroke. EPCs were counted with flow cytometry. Stroke severity and outcome were assessed using the National Institutes of Health Stroke Scale, Barthel Index and modified Rankin Scale. The levels of key elements known to affect EPC characteristics were measured by ELISA. Diminished total antioxidant capacity and CD34 + KDR + and CD133 + KDR + counts in early phases of stroke were associated with disease severity and worse functional outcome at day 90 post-stroke. Baseline levels of angiogenic agent PDGF-BB, but not VEGF, positively correlated with CD34 + KDR + numbers at day 90. Baseline LDL-cholesterol levels were inversely correlated with CD34 + KDR+, CD133 + KDR + and CD34 + CD133 + KDR + numbers at day 90. Close correlation between baseline CD34 + KDR + and CD133 + KDR + counts and the outcome of stroke proposes these particular EPC subtypes as potential prognostic markers for ischaemic stroke.

Marine Compound Exerts Antiaging Effect in Human Endothelial Progenitor Cells via Increasing Sirtuin1 Expression

Aging is associated with an increased risk of cardiovascular disease. Previous studies have demonstrated that compound 3 (C3), a derivative of marine compound xyloallenoide A isolated from the mangrove fungus Xylaria sp. (no. 2508), exhibited strong angiogenic activities in zebrafish. In this study, we examined the effects of C3 on the senescence of endothelial progenitor cells isolated from human peripheral blood (hEPCs). The results showed that treatment with angiotensin II (AngII) for 24 h induced hEPC senescence, as demonstrated by increased SA-β-galactosidase staining. Moreover, there is a significant decrease in telomerase activity and cellular viability in AngII-treated hEPCs. These changes in aging hEPCs were greatly recovered by C3 in a dose-dependent manner. Furthermore, C3 significantly restored the AngII-induced decrease of sirtuin type 1 (SIRT1) expression, a well-known antiaging protein. In addition, AngII increased AMP-activated protein kinase (AMPK) phosphorylation and reduced Akt phosphorylation in aging hEPCs, which were also reversed by C3. Importantly, the inhibition of C3 on hEPC senescence and AMPK/Akt dysregulation was significantly attenuated by the SIRT1-specific inhibitor nicotinoyl. These results indicated that C3 protects hEPC against AngII-induced senescence by increasing SIRT1 expression levels and balancing the AMPK/Akt signaling pathway. The inhibition of hEPCs senescence by C3 might protect EPCs against dysfunction induced by pathological factors in the elderly population. C3 may provide a novel drug candidate for the treatment of aging-related disorders.

MCPIP-1 knockdown enhances endothelial colony-forming cell angiogenesis via the TFRC/AKT/mTOR signaling pathway in the ischemic penumbra of MCAO mice

Cerebral ischemia is a serious disease characterized by brain tissue ischemia and hypoxic necrosis caused by the blockage of blood vessels within the central nervous system. Although stem cell therapy is a promising approach for treating ischemic stroke, the inflammatory, oxidative, and hypoxic environment generated by cerebral ischemia greatly reduces the survival and therapeutic effects of transplanted stem cells. Endothelial colony-forming cells (ECFCs) are a class of precursor cells with strong proliferative potential that can migrate and differentiate directly into mature vascular endothelial cells. Consequently, ECFCs can exert significant therapeutic and reparative effects in diseases associated with vascular injury. Monocyte chemoattractant protein-induced protein 1 (MCPIP-1) exerts multiple biological effects; however, no studies have yet reported its role in the angiogenic function of ECFCs. In this study, we performed Proteome Profiler™ Human Angiogenesis Antibody arrays and tandem mass tag protein profiling to investigate the effect of MCPIP-1 on ECFCs. We demonstrated that MCPIP-1 knockdown enhanced the proliferation, migration, and in vivo and in vitro angiogenic capacity of ECFCs by upregulating the transferrin receptor-activated AKT/m-TOR signaling pathway to promote cellular trophic factor secretion. Furthermore, we found that the lateral ventricular transplantation of ECFCs with lentiviral MCPIP-1 knockdown into mice with middle cerebral artery occlusion increased serum vacular endothelial growth factor(VEGF), angiopoietin-1, and HIF-1a levels, enhanced neovascularization and neurogenesis in the ischemic penumbra, reduced the size of cerebral infarcts, and promoted neurological recovery. Together, these findings suggest new avenues for enhancing the therapeutic efficacy of ECFCs.

Endothelial progenitor cells as an emerging cardiovascular risk factor in the field of food and nutrition research: advances and challenges

Dietary modifications can help prevent many cardiovascular disease (CVD) events. Endothelial progenitor cells (EPCs) actively contribute to cardiovascular system maintenance and could function as surrogate markers for evaluating improvement in cardiovascular health resulting from nutritional interventions. This review summarizes the latest research progress on the impact of food and nutrients on EPCs, drawing on evidence from human, animal, and in vitro studies. Additionally, current trends and challenges faced in the field are highlighted. Findings from studies examining cells as EPCs are generally consistent, demonstrating that a healthy diet, such as the Mediterranean diet or a supervised diet for overweight people, specific foods like olive oil, fruit, vegetables, red wine, tea, chia, and nutraceuticals, and certain nutrients such as polyphenols, unsaturated fats, inorganic nitrate, and vitamins, generally promote higher EPC numbers and enhanced EPC function. Conversely, an unhealthy diet, such as one high in sugar substitutes, salt, or fructose, impairs EPC function. Research on outgrowth EPCs has revealed that various pathways are involved in the modulation effects of food and nutrients. The potential of EPCs as a biomarker for assessing the effectiveness of nutritional interventions in preventing CVDs is immense, while further clarification on definition and characterization of EPCs is required.

Vascular Ageing: Mechanisms, Risk Factors, and Treatment Strategies

Ageing constitutes the biggest risk factor for poor health and adversely affects the integrity and function of all the cells, tissues, and organs in the human body. Vascular ageing, characterised by vascular stiffness, endothelial dysfunction, increased oxidative stress, chronic low-grade inflammation, and early-stage atherosclerosis, may trigger or exacerbate the development of age-related vascular diseases, which each year contribute to more than 3.8 million deaths in Europe alone and necessitate a better understanding of the mechanisms involved. To this end, a large number of recent preclinical and clinical studies have focused on the exponential accumulation of senescent cells in the vascular system and paid particular attention to the specific roles of senescence-associated secretory phenotype, proteostasis dysfunction, age-mediated modulation of certain microRNA (miRNAs), and the contribution of other major vascular risk factors, notably diabetes, hypertension, or smoking, to vascular ageing in the elderly. The data generated paved the way for the development of various senotherapeutic interventions, ranging from the application of synthetic or natural senolytics and senomorphics to attempt to modify lifestyle, control diet, and restrict calorie intake. However, specific guidelines, considering the severity and characteristics of vascular ageing, need to be established before widespread use of these agents. This review briefly discusses the molecular and cellular mechanisms of vascular ageing and summarises the efficacy of widely studied senotherapeutics in the context of vascular ageing.

The gastrointestinal-brain-microbiota axis: a promising therapeutic target for ischemic stroke

Ischemic stroke is a highly complex systemic disease characterized by intricate interactions between the brain and gastrointestinal tract. While our current understanding of these interactions primarily stems from experimental models, their relevance to human stroke outcomes is of considerable interest. After stroke, bidirectional communication between the brain and gastrointestinal tract initiates changes in the gastrointestinal microenvironment. These changes involve the activation of gastrointestinal immunity, disruption of the gastrointestinal barrier, and alterations in gastrointestinal microbiota. Importantly, experimental evidence suggests that these alterations facilitate the migration of gastrointestinal immune cells and cytokines across the damaged blood-brain barrier, ultimately infiltrating the ischemic brain. Although the characterization of these phenomena in humans is still limited, recognizing the significance of the brain-gastrointestinal crosstalk after stroke offers potential avenues for therapeutic intervention. By targeting the mutually reinforcing processes between the brain and gastrointestinal tract, it may be possible to improve the prognosis of ischemic stroke. Further investigation is warranted to elucidate the clinical relevance and translational potential of these findings.

Evaluation of Endothelial Progenitor Cell Characteristics as Clinical Biomarkers for Elderly Patients with Ischaemic Stroke

Ageing impairs endothelial function and predisposes the person to ischaemic stroke (IS). Endothelial progenitor cells (EPCs) repair endothelial damage and induce post-ischaemic neovascularisation. Given the prevalence of IS in older population, this study explored whether changes in EPC number and function may reliably predict the type or outcome of stroke in patients ≥ 65 years of age. For this, blood samples were collected once from healthy volunteers (HVs, n = 40) and four times (admission and days 7, 30 and 90 post-stroke) from participants with lacunar (n = 38) or cortical (n = 43) stroke. EPCs were counted with flow cytometry and defined as non-haematopoietic cells (CD45-) expressing markers for stemness (CD34 +), immaturity (CD133 +) and endothelial maturity (KDR +). Clonogenesis, tubulogenesis, migration and proliferation assays were performed as measures of EPC functionality. Biochemical profile of plasma inflammatory and angiogenic agents were studied using specific ELISAs. Primary outcome was disability or dependence on day 90 post-stroke, assessed by the modified Rankin Scale (mRS). Compared to HVs, EPC numbers were higher in stroke patients at all time points studied, reaching significance at baseline and day 30. No differences in EPC counts and functionality were observed between lacunar and cortical stroke groups at any time. Plasma endostatin, PDGF-BB, TNF-α and VEGF levels were higher in stroke patients vs HVs. Patient outcome, evaluated by mRS on day 90 post-stroke, did not correlate with EPC count or functionality. Baseline EPC counts may serve as a diagnostic marker for stroke but fail to distinguish between different stroke subtypes and predict post-stroke outcome.

Outgrowth Endothelial Cell Conditioned Medium Negates TNF-α-Evoked Cerebral Barrier Damage: A Reverse Translational Research to Explore Mechanisms

Improved understanding of the key mechanisms underlying cerebral ischemic injury is essential for the discovery of efficacious novel therapeutics for stroke. Through detailed analysis of plasma samples obtained from a large number of healthy volunteers (n = 90) and ischemic stroke patients (n = 81), the current study found significant elevations in the levels of TNF-α at baseline (within the first 48 h of stroke) and on days 7, 30, 90 after ischaemic stroke. It then assessed the impact of this inflammatory cytokine on an in vitro model of human blood-brain barrier (BBB) and revealed dramatic impairments in both barrier integrity and function, the main cause of early death after an ischemic stroke. Co-treatment of BBB models in similar experiments with outgrowth endothelial cell-derived conditioned media (OEC-CM) negated the deleterious effects of TNF-α on BBB. Effective suppression of anti-angiogenic factor endostatin, stress fiber formation, oxidative stress, and apoptosis along with concomitant improvements in extracellular matrix adhesive and tubulogenic properties of brain microvascular endothelial cells and OECs played an important role in OEC-CM-mediated benefits. Significant increases in pro-angiogenic endothelin-1 and monocyte chemoattractant protein-1 in OEC-CM compared to the secretomes of OEC and HBMEC, detected by proteome profiling assay, accentuate the beneficial effects of OEC-CM. In conclusion, this reverse translational study identifies TNF-α as an important mediator of post-ischemic cerebral barrier damage and proposes OEC-CM as a potential vasculoprotective therapeutic strategy by demonstrating its ability to regulate a wide range of mechanisms associated with BBB function. Clinical trial registration NCT02980354.

Mapping the research trends of astrocytes in stroke: A bibliometric analysis

Background

Stroke, including ischemic stroke and hemorrhagic stroke, possesses complex pathological mechanisms such as neuroinflammation, oxidative stress and blood-brain barrier damage. Astrocyte functions have been reported during injury, neuroprotection and cell crosstalk. It plays a key role in exacerbating stroke injury, promoting neurological repair and enhancing neuroregeneration.

Aim

This holistic bibliometric analysis aimed to provide a general overview of the recent advancement and the hotspots in the field of stroke and astrocyte from 2001 to 2021.

Materials and methods

Publications between 2001 and 2021, related to stroke and astrocyte were retrieved from the Web of Science (WOS) and analyzed in Gephi and VOSviewer.

Results

In total, 3789 documents were extracted from the WOS databases. The publications showed stable growth since 2001. The United States and China were the most prolific countries and University of California San Francisco and Oakland University were the most influential institutes. The top four most productive journals were Brain Research, Journal of Cerebral Blood Flow and Metabolism, Glia and Journal of Neuroinflammation. Keywords frequency and co-occurrence analysis revealed that the topics related to “micro-RNA”, “toll like receptor”, “neuroinflammation”, “autophagy” and “interleukin” were research frontiers. The field of stroke and astrocyte focused on several aspects, such as the role of astrocytes in the treatment of stroke, metabolic changes in astrocytes, the protective role of apoptosis in astrocytes after oxidative stress injury and neurovascular units.

Conclusion

This comprehensive bibliometric study provides an updated perspective on the trend of research associated with stroke and astrocyte. It will benefit scientific community to identify the important issues, future directions and provide a novel understanding of stroke pathophysiology, hotspots and frontiers to facilitate future research direction.

Exosome in Crosstalk between Inflammation and Angiogenesis: A Potential Therapeutic Strategy for Stroke

The endothelial dysfunction, associated with inflammation and vascular permeability, remains the key event in the pathogenesis of cerebral ischemic stroke. Angiogenesis is essential for neuroprotection and neural repair following stroke. The neuroinflammatory reaction plays a vital role in stroke, and inhibition of inflammation contributes to establishing an appropriate external environment for angiogenesis. Exosomes are the heterogeneous population of extracellular vesicles which play critical roles in intercellular communication through transmitting various proteins and nucleic acids to nearby and distant recipient cells by body fluids and circulation. Recent reports have shown that exosomal therapy is a valuable and potential treatment strategy for stroke. In this review, we discussed the exosomes in complex interaction mechanisms of angiogenesis and inflammation following stroke as well as the challenges of exosomal studies such as secretion, uptake, modification, and application.

Protein kinase C-β distinctly regulates blood-brain barrier-forming capacity of Brain Microvascular endothelial cells and outgrowth endothelial cells

Outgrowth endothelial cells (OECs) provide an endogenous repair mechanism and thus maintain endothelial barrier integrity. As inhibition of protein kinase C-β (PKC-β) activity has been shown to attenuate endothelial damage in various pathological conditions including hyperglycaemia and ischaemic injury, the present study comparatively assessed the effect of LY333531, a PKC-β inhibitor, on the cerebral barrier integrity formed by OECs or human brain microvascular endothelial cells (HBMECs). To this end, an in vitro model of human BBB established by co-culture of astrocytes and pericytes with either OECs or HBMECs was exposed to 4 h of oxygen-glucose deprivation with/out LY333531 (0.05 µM). The inhibition of PKC-β protected the integrity and function of the BBB formed by HBMECs, as evidenced by increases in transendothelial electrical resistance and decreases in sodium fluorescein flux. It also attenuated ischaemia-evoked actin cytoskeleton remodelling, oxidative stress, and apoptosis in HBMECs. In contrast, treatments with LY333531 exacerbated the deleterious effect of ischaemia on the integrity and function of BBB formed by OECs while augmenting the levels of oxidative stress, apoptosis, and cytoskeletal reorganisation in OECs. Interestingly, the magnitude of damage in all aforementioned parameters, notably oxidative stress, was lower with low dose of LY333531 (0.01 µM). It is therefore possible that the therapeutic concentration of LY333531 (0.05 µM) may neutralise the activity of NADPH oxidase and thus trigger a negative feedback mechanism which in turn exacerbate the detrimental effects of ischaemic injury. In conclusion, targeting PKC-β signalling pathway in ischaemic settings requires close attention while using OECs as cellular therapeutic.

Delay of endothelial cell senescence protects cerebral barrier against age-related dysfunction: role of senolytics and senomorphics

Accumulation of senescent cells in cerebrovasculature is thought to play an important role in age-related disruption of blood-brain barrier (BBB). Using an in vitro model of human BBB, composed of brain microvascular endothelial cells (BMECs), astrocytes and pericytes, this study explored the so-called correlative link between BMEC senescence and the BBB dysfunction in the absence or presence of functionally distinct senotherapeutics. Replicative senescence was deemed present at passage ≥19 where BMECs displayed shortened telomere length, reduced proliferative and tubulogenic potentials and increased NADPH oxidase activity, superoxide anion production (markers of oxidative stress), S-β-galactosidase activity and γ-H2AX staining. Significant impairments observed in integrity and function of a model of BBB established with senescent BMECs, ascertained successively by decreases in transendothelial electrical resistance and increases in paracellular flux, revealed a close correlation between endothelial cell senescence and BBB dysfunction. Disruptions in the localization or expression of tight junction proteins, zonula occludens-1, occludin, and claudin-5 in senescent BMECs somewhat explained this dysfunction. Indeed, treatment of relatively old BMEC (passage 16) with a cocktail of senolytics (dasatinib and quercetin) or senomorphics targeting transcription factor NF-κB (QNZ), p38MAPK signaling pathway (BIRB-796) or pro-oxidant enzyme NADPH oxidase (VAS2870) until passage 20 rendered these cells more resistant to senescence and totally preserved BBB characteristics by restoring subcellular localization and expression of tight junction proteins. In conclusion, attempts that effectively mitigate accumulation of senescent endothelial cells in cerebrovasculature may prevent age-related BBB dysfunction and may be of prophylactic or therapeutic value to extend lifelong health and wellbeing.

MicroRNA: An Emerging Predictive, Diagnostic, Prognostic and Therapeutic Strategy in Ischaemic Stroke

Stroke continues to be the third-leading cause of death and disability worldwide. The limited availability of diagnostic tools approved therapeutics and biomarkers that help monitor disease progression or predict future events remain as the major challenges in the field of stroke medicine. Hence, attempts to discover safe and efficacious therapeutics and reliable biomarkers are of paramount importance. MicroRNAs (miRNAs) are a class of non-coding RNAs that play important roles in regulating gene expression. Since miRNAs also play important roles in key mechanisms associated with the pathogenesis of stroke, including energy failure, inflammation and cell death, it is possible that miRNAs may serve as reliable blood-based markers for risk prediction, diagnosis and prognosis of ischaemic stroke. Discovery of better neurological outcome and smaller cerebral infarcts in animal models of ischaemic stroke treated with miRNA agomirs or antagomirs indicate that miRNAs may also play a cerebrovascular protective role after an ischaemic stroke. Nonetheless, further evidences on the optimum time for treatment and route of administration are required before effective translation of these findings into clinical practice. Bearing these in mind, this paper reviews the current literature discussing the involvement of miRNAs in major pathologies associated with ischaemic stroke and evaluates their value as reliable biomarkers and therapeutics for ischaemic stroke.

Air Pollution Exposure Induces Vascular Injury and Hampers Endothelial Repair by Altering Progenitor and Stem Cells Functionality

Extensive evidence indicates an association of air pollution exposure with an increased risk of cardiovascular disease (CVD) development. Fine particulate matter (PM) represents one of the main components of urban pollution, but the mechanisms by which it exerts adverse effects on cardiovascular system remain partially unknown and under investigation. The alteration of endothelial functions and inflammation are among the earliest pathophysiological impacts of environmental exposure on the cardiovascular system and represent critical mediators of PM-induced injury. In this context, endothelial stem/progenitor cells (EPCs) play an important role in vascular homeostasis, endothelial reparative capacity, and vasomotor functionality modulation. Several studies indicate the impairment of EPCs' vascular reparative capacity due to PM exposure. Since a central source of EPCs is bone marrow (BM), their number and function could be related to the population and functional status of stem cells (SCs) of this district. In this review, we provide an overview of the potential mechanisms by which PM exposure hinders vascular repair by the alteration of progenitor and stem cells' functionality.

Advances in the Pharmacological Intervention of Endothelial Progenitor Cells in the Treatment of Ischemic Stroke

BACKGROUND

Ischemic stroke, a common central nervous system disease that seriously threatens human life and health, is characterized by rapid progress and a high disability fatality rate. Ischemic tissue can produce a large amount of vascular endothelial growth factor (VEGF) and stromal cell-derived factor 1 (SDF-1) to promote the mobilization of endothelial progenitor cells (EPCs).

SUMMARY

As newly discovered stem cells, EPCs can promote angiogenesis in ischemic tissue, repair the damaged vascular endothelium, and maintain vascular homeostasis. Thus, EPCs have become a new research hotspot in this field. This review focuses on the mechanism of EPCs and the intervention of various novel drugs, including small molecules and biomolecules, which will promote the capture, proliferation, and differentiation of EPCs. Then, we explore the promotion of vascular health and the prospect of its application in the treatment of cerebral ischemic stroke (CIS).

KEY MESSAGE

It is clinically significant to study the potential of new drug therapy to target EPCs. More effective cytokines, signal pathways, and other drugs should be explored in the future and their specific mechanisms determined. Research should reveal more biological functions of EPCs and achieve their efficient amplification to improve therapy against CIS stroke.

Treatment with outgrowth endothelial cells protects cerebral barrier against ischemic injury

BACKGROUND AND AIMS

We have previously reported that outgrowth endothelial cells (OECs) restore cerebral endothelial cell integrity through effective homing to the injury site. This study further investigates whether treatment with OECs can restore blood-brain barrier (BBB) function in settings of ischemia-reperfusion injury both in vitro and in vivo.

METHODS

An in vitro model of human BBB was established by co-culture of astrocytes, pericytes, and human brain microvascular endothelial cells (HBMECs) before exposure to oxygen-glucose deprivation alone or followed by reperfusion (OGD±R) in the absence or presence of exogenous OECs. Using a rodent model of middle cerebral artery occlusion (MCAO), we further assessed the therapeutic potential of OECs in vivo.

RESULTS

Owing to their prominent antioxidant, proliferative, and migratory properties, alongside their inherent capacity to incorporate into brain vasculature, treatments with OECs attenuated the extent of OGD±R injury on BBB integrity and function, as ascertained by increases in transendothelial electrical resistance and decreases in paracellular flux across the barrier. Similarly, intravenous delivery of OECs also led to better barrier protection in MCAO rats as evidenced by significant decreases in ipsilateral brain edema volumes on day 3 after treatment. Mechanistic studies subsequently showed that treatment with OECs substantially reduced oxidative stress and apoptosis in HBMECs subjected to ischemic damages.

CONCLUSION

This experimental study shows that OEC-based cell therapy restores BBB integrity in an effective manner by integrating into resident cerebral microvascular network, suppressing oxidative stress and cellular apoptosis.

Construction of a Joint Prediction Model for the Occurrence of Ischemic Stroke and Acute Myocardial Infarction Based on Bioinformatic Analysis

Ischemic stroke (IS) has imposed significant threat to both middle-aged and elderly people worldwide. Acute myocardial infarction (AMI) is a rare but serious complication following IS, which can further increase patient disability and mortality rates. With the development of intravenous thrombolysis and endovascular treatment, the prognosis of IS has been greatly improved. However, the pathogenesis of IS complicated with AMI is still unclear. To fill this gap, this work uses bioinformatic analysis, where IS and AMI datasets were combined for differential gene analysis, and then, a ROC prediction model for target gene analysis was constructed. It is found that OSM gene has the highest prediction accuracy (AUC = 0.793), followed by IL6ST, IL6, JAK1, IL6R, and JAK2 genes. Joint prediction model showed higher accuracy in predicting the outcome of control and case (AUC = 0.918). The etiology of ischemic stroke and acute myocardial infarction is complicated. Their cooccurring pathological mechanisms and the conversion between the two diseases could not be explained by a single gene. Therefore, the joint prediction model in this work can provide a better prediction accuracy for research purpose.

Clinical relevance of circulating angiogenic cells in patients with ischemic stroke

Background

Endothelial progenitor cells (EPCs) are circulating angiogenic cells with endothelial features associated with risk for stroke. We aimed to delve into their functional characteristics. EPCs were isolated and cultured from Ischemic Stroke (IS) patients and predictors of their variance evaluated.

Methods

This is a single-center observational study evaluating 187 consecutively hospitalized patients with IS. EPCs were isolated from blood samples. The number of circulating angiogenic cells (CACs), colony-forming units (CFU-ECs) and the emergence of late outgrowths endothelial cells (LOECs) were counted. We collected clinical variables and measured the stromal cell-derived factor 1 alpha (SDF1α) serum levels. We also examined the relative telomere length and the expression of osteogenic gene markers in CACs.

Results

CACs counts and CFU-ECs colony numbers were positively correlated (rho = 0.41, p < 0.001, n = 187). We found significant differences according to whether thrombolytic treatment was performed in the distribution of CFU-ECs (odds ratio (OR) = 2.5; 95% confidence interval (CI) 1.01–6.35; p = 0.042) and CACs (OR = 4.45; 95% IC 1.2–15.5; p = 0.012). The main determinants of CACs variation were the number of risks factors, thrombolysis treatment, arterial hypertension, LOECs occurrence, and the vascular endothelial growth factor expression, whereas CFU-ECs variations depended on hemoglobin content and the relative reduction in the National Institutes of Health Stroke Scale (NIHSS) criteria. The main predictors of LOECs appearance were thrombolysis and length of hospital stay.

Conclusions

Our study supports the relevance of patient risk factors and treatments in the analysis of the functional properties of EPCs.

Evaluation of circulating endothelial progenitor cells and the severity of transient ischemic attack

OBJECTIVE

Endothelial progenitor cells (EPCs) are believed to have a positive effect on maintaining endothelial integrity and participate in angiogenesis after cerebral infarction. Numerous studies have demonstrated that EPCs promote ischemic tissue angiogenesis after stroke. However, there are few studies on the relationship between the level of EPCs and the severity of transient ischemic attacks (TIAs). The current study aimed to investigate the evaluation value of EPCs and serum stromal cell-derived factor-1α(SDF-1α) levels on the severity of TIA.

METHODS

A total of 144 patients with TIA who had an onset of symptoms within 24 h were enrolled and divided into a high-risk TIA (HR-TIA) group (79 cases) and a nonhigh-risk TIA (NHR-TIA) group (65 cases). Clinical data of these patients were collected. Flow cytometry (FCM) was used to measure the number of CD34⁺KDR⁺ EPCs, and enzyme-linked immunosorbent assay (ELISA) was used to determine the concentration of serum SDF-1α and vascular endothelial growth factor (VEGF). Fifteen healthy donors were selected as the normal control (NC) group. Circulating EPCs were isolated by density gradient centrifugation from the first 15 patients in the high-risk TIA group, the nonhigh-risk TIA group, and the NC group. A colony assay and MTT assay were used to determine the proliferation ability of each group, and a Boyden chamber was used to determine the migration potential of EPCs.

RESULTS

Compared with the nonhigh-risk group, patients in the high-risk TIA group were older and had a higher incidence of hypertension and diabetes and stroke recurrence. Patients in the high-risk TIA group had higher levels of triglycerides, cholesterol, and low-density lipoprotein. However, there were no significant differences between the two groups in sex, time from onset to blood draw, smoking, body mass index, or homocysteine (P > 0.05). The number of circulating EPCs in the nonhigh-risk TIA group was higher than that in the high-risk TIA group (P < 0.01). SDF-1α and VEGF levels in the nonhigh-risk TIA group were lower than those in the high-risk TIA group (P < 0.01). The results of multivariate regression analysis showed that age, hypertension, diabetes, smoking, and SDF-1α were risk factors for high-risk TIA, and EPCs were protective factors for high-risk TIA. EPCs were separated and cultured for 72 h. Compared with the NC group, EPCs functions were weakened in the high-risk TIA group and nonhigh-risk TIA group (P < 0.05). Compared with the nonhigh-risk TIA group, EPC functions were decreased in the high-risk TIA group (P < 0.01).

CONCLUSION

CD34⁺KDR⁺ EPCs are protective factors for high-risk TIA. The number of circulating CD34⁺KDR⁺ EPCs and the concentration of SDF-1α have important clinical value in predicting the progression of TIA to high-risk TIA.

Outgrowth endothelial progenitor cells restore cerebral barrier function following ischaemic damage: the impact of NOX2 inhibition

Disruption of blood-brain barrier (BBB), formed mainly by human brain microvascular endothelial cells (HBMECs), constitutes the major cause of mortality following ischaemic stroke. This study investigates whether OECs (outgrowth endothelial cells) can restore BBB integrity and function following ischaemic damage, and how inhibition of NOX2, a main source of vascular oxidative stress, affects the characteristics of BBB established with OECs and HBMECs in ischaemic settings. In vitro models of human BBB were constructed by co-culture of pericytes and astrocytes with either OECs or HBMECs before exposure to oxygen-glucose deprivation (OGD) alone or followed by reperfusion (OGD+R) in the absence or presence of NOX2 inhibitor, gp91ds-tat. The function and integrity of BBB were assessed by measurements of paracellular flux of sodium fluorescein (NaF) and transendothelial electrical resistance (TEER), respectively. Treatment with OECs during OGD+R effectively restored BBB integrity and function. Compared to HBMECs, OECs possessed lower NADPH oxidase activity, superoxide anion levels, and had greater total antioxidant capacity during OGD and OGD+R. Inhibition of NADPH oxidase during OGD and OGD+R restored the integrity and function of BBB established by HBMECs. This was evidenced by reductions in NADPH oxidase activity and superoxide anion levels. In contrast, treatment with gp91ds-tat aggravated ischaemic injury-induced BBB damage constructed by OECs. In conclusion, OECs are more resistant to ischaemic conditions and can effectively repair cerebral barrier following ischaemic damage. Suppression of oxidative stress through specific targeting of NOX2 requires close attention while using OECs as therapeutics.

The "Dialogue" Between Central and Peripheral Immunity After Ischemic Stroke: Focus on Spleen

The immune response generated by the body after the incidence of ischemic stroke, runs through the comprehensive process of aftermath. During this process of ischemic stroke, the central neuroinflammation and peripheral immune response seriously affect the prognosis of patients, which has been the focus of research in recent years. As this research scenario progressed, the "dialogue" between central nervous inflammation and peripheral immune response after ischemic stroke has become more closely related. It's worth noting that the spleen, as an important peripheral immune organ, plays a pivotal role in this dialogue. Multiple mechanisms have previously been reported for brain-spleen crosstalk after ischemic stroke. Further, neuroinflammation in the brain can affect the peripheral immune state by activating/inhibiting spleen function. However, the activation of the peripheral immune inflammatory response can work reversibly in the spleen. It further affects intracerebral neuroinflammation through the injured blood-brain barrier. Therefore, paying close attention to the role of spleen as the pivot between central and peripheral immunity in ischemic stroke may help to provide a new target for immune intervention in the treatment of ischemic stroke. In the present review, we reviewed the important role of spleen in central neuroinflammation and peripheral immune response after ischemic stroke. We summarized the relevant studies and reports on spleen as the target of immune intervention which can provide new ideas for the clinical treatment of ischemic stroke.

Differential MicroRNA Expression Pattern in Endothelial Progenitor Cells During Diabetic Retinopathy

Endothelial progenitor cells (EPCs) are involved in the pathogenesis of microvascular dysfunction in diabetic retinopathy (DR). MicroRNAs (miRNAs) serve as crucial regulators in many biological process and human diseases. Herein, to investigate the expression profile and possible role of miRNAs in EPCs, small RNA sequencing was conducted to identify EPC dysfunction-related miRNAs in DR. A total of 72 miRNAs were differentially expressed in EPCs following high glucose stress. Based on Gene Ontology (GO) analysis, the target genes of differentially expressed miRNAs were targeted to “protein binding,” “cell differentiation,” and “cytoskeleton.” Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that cGMP-PKG signaling pathway was tightly associated with miRNA-mediated EPC function. Furthermore, miR-375–3p was verified to be up-regulated in the clinical samples of DR patients. Inhibition of miR-375–3p protected against hyperglycemic stress- or hypoxic stress-induced EPC injury, which increased the viability, proliferation, migration, and tube formation ability of EPCs and retarded the development of apoptosis. Collectively, this study provides a novel insight into the pathogenesis of EPC dysfunction in DR. miR-375–3p is a potential target for the diagnosis or treatment of DR.

Up-regulated miR-204-5p promoted the migration, invasion, and angiogenesis of endothelial progenitor cells to enhance the thrombolysis of rats with deep venous thrombosis by targeting SPRED1

Deep venous thrombosis (DVT) endangers human health. Endothelial progenitor cells (EPCs) were proven to promote thrombolysis and miR-204-5p was discovered to be low-expressed in DVT patients. This study concentrated on exploring whether miR-204-5p had a regulatory effect on EPCs and DVT. Concretely, the expression of miR-204-5p in DVT patients' blood was detected by qRT-PCR. The target of miR-204-5p was predicted by bioinformatics and verified by dual-luciferase reporter assay. After rat EPCs were isolated, identified, and transfected with miR-204-5p agomiR, antagomiR, or SPRED1 plasmids, the viability, migration, invasion, and tube formation of EPCs were detected by MTT, wound healing, Transwell, and tube formation assays, respectively. MiR-204-5p, SPRED1, p-PI3K, PI3K, p-AKT, AKT, VEGFA, and Ang1 expressions in EPCs were measured by qRT-PCR or Western blot. EPCs transfected with miR-204-5p overexpression lentivirus plasmid were injected into the DVT rat model. The histopathology of the thrombus and the homing of EPCs to thrombus in the DVT rats were observed by hematoxylin-eosin staining and confocal microscopy, respectively. We found that miR-204-5p was low-expressed in DVT patients and SPRED1 was a target gene of miR-204-5p. MiR-204-5p agomiR promoted the viability, migration, invasion, and tube formation of EPCs, the levels of VEGFA and Ang1 and the activation of PI3K/AKT pathway in EPCs, while miR-204-5p antagomiR and SPRED1 worked oppositely. SPRED1 reversed the effect of miR-204-5p agomiR on EPCs. Up-regulated miR-204-5p inhibited thrombosis and promoted EPCs homing to thrombus in DVT rats. Collectively, up-regulated miR-204-5p enhanced the angiogenesis of EPCs and thrombolysis in DVT rats by targeting SPRED1.

Low-Dose Piperlongumine Rescues Impaired Function of Endothelial Progenitor Cells and Reduces Cerebral Ischemic Injury in High-Fat Diet-Fed Mice

It is of great clinical significance to develop potential novel strategies to prevent cardio-cerebrovascular complications in patients with hyperlipidemia. Vascular Endothelial integrity and function play a key role in the prevention of cardio-cerebrovascular diseases. Endothelial progenitor cells (EPCs) can home to sites of ischemic injury and promote endothelial regeneration and neovascularization. Hypercholesterolemia impairs the function of EPC. The present study attempted to identify the effect of piperlongumine on EPCs’ angiogenic potential and cerebral ischemic injury in high-fat diet-fed (HFD-fed) mice. Here, we showed that treatment with low-does piperlongumine (0.25 mg/kg/day) for 8 weeks significantly improved EPCs function and reduced the cerebral ischemic injury (both infarct volumes and neurobehavioral outcomes) in HFD-fed mice. In addition, low-dose piperlongumine administration increased intracellular NO level and reduced intracellular O₂^- level in EPCs of HFD-fed mice. Moreover, incubation with piperlongumine (1.0 μM, 24 h) reduced thrombospondin-1/2 (TSP-1/2, a potent angiogenesis inhibitor) expression levels in EPCs from HFD-fed mice, increased the therapeutic effect of EPC from HFD-fed mice on cerebral ischemic injury reduction and angiogenesis promotion in HFD-fed mice, and the donor derived EPCs homed to the recipient ischemic brain. In conclusion, low-dose piperlongumine can enhance EPCs’ angiogenic potential and protect against cerebral ischemic injury in HFD-fed mice. It is implied that treatment with low-dose piperlongumine might be a potential option to prevent ischemic diseases (including stroke) in patients with hyperlipidemia, and priming with piperlongumine might be a feasible way to improve the efficacy of EPC-based therapy for ischemic diseases.

CD146 mediates the anti-apoptotic role of Netrin-1 in endothelial progenitor cells under hypoxic conditions

Modulating the biological status of endothelial progenitor cells (EPCs), such as function and survival, is essential for therapeutic angiogenesis in ischemic vascular disease environments. This study aimed to explore the role and molecular mechanisms underlying Netrin-1 in the viability and angiogenic function of EPCs. EPCs were isolated from the bone barrow of adult C57/BL6 mice. The apoptosis and various functions of EPCs were analyzed in vitro by manipulating the expression of Netrin-1. The TUNEL assay was performed to detect apoptotic EPCs. Cell migration and tube formation assays were performed to detect EPC function. Trypan blue staining was performed to detect cell viability. Western blot analysis was performed to detect the protein expression levels of Netrin-1, CD146 and apoptotic factors. Quantitative PCR analysis was performed to detect the expression levels of Netrin-1 receptors. The results demonstrated that treatment with exogenous Netrin-1 promoted EPC migration and tube formation, whereas transfection with small interfering (si)RNA targeting Netrin-1 exhibited the opposite effects. Exogenous Netrin-1 protected EPCs from hypoxia-induced apoptosis, whereas the interruption of endogenous Netrin-1 enhancement under hypoxia by Netrin-1-siRNA exacerbated the apoptosis of EPCs. Furthermore, CD146, one of the immunoglobulin receptors activated by Netrin-1, was screened for in the present study. Results demonstrated that CD146 did not participate in Netrin-1-promoted EPC function, but mediated the anti-apoptotic effects of Netrin-1 in EPCs. In conclusion, Netrin-1 enhanced the angiogenic function of EPCs and alleviated hypoxia-induced apoptosis, which was mediated by CD146. This biological function of Netrin-1 may provide a potential therapeutic option to promote EPCs for the treatment of ischemic vascular diseases.

Evaluation of fine particulate matter on vascular endothelial function in vivo and in vitro

Ambient fine particulate matter (PM_2.5) and high-fat diet (HFD) are linked to the development of atherosclerosis. However, there is still unknown about the PM_2.5-induced atherosclerosis formation on vascular endothelial injury after co-exposed to PM_2.5 and HFD. Thus, the aim of this study was to evaluate the effects of PM_2.5 on atherogenesis in C57BL/6 mice and endothelial cells, as well as the co-exposure effect of PM_2.5 and HFD. In vivo study, C57BL/6 mice exposed to PM_2.5 and fed with standard chow diet (STD) or HFD for 1 month. PM_2.5 could increase vascular stiffness accessed by Doppler ultrasound, and more serious in co-exposure group. PM_2.5 impaired vascular endothelial layer integrity, exfoliated endothelial cells, and inflammatory cells infiltration through H&E staining. PM_2.5 reduced the expression of platelet/endothelial cell adhesion molecule-1 (PECAM-1) in vessel. Moreover, PM_2.5 could induce systemic inflammation detected by Mouse Inflammation Array. In vitro study, PM_2.5 triggered markedly mitochondrial damage by transmission electron microscope (TEM) and flow cytometer. Inflammatory cytokines were significantly increased in PM_2.5-exposed group. The cell viability and migration of endothelial cells were significantly suppressed. In addition, PM_2.5 remarkably declined the expression of vascular endothelial growth factor receptor 2 (VEGFR2) and increased the expression of somatostatin (SST) and its receptor. In conclusion, co-exposure of PM_2.5 and HFD might induce systemic inflammation and endothelial dysfunction in normal mice. Moreover, PM_2.5 could reduce vascular endothelial repair capacity through inhibiting the proliferation and migration of endothelial cells.

Construction of transplantable artificial vascular tissue based on adipose tissue-derived mesenchymal stromal cells by a cell coating and cryopreservation technique

Prevascularized artificial three-dimensional (3D) tissues are effective biomaterials for regenerative medicine. We have previously established a scaffold-free 3D artificial vascular tissue from normal human dermal fibroblasts (NHDFs) and umbilical vein-derived endothelial cells (HUVECs) by layer-by-layer cell coating technique. In this study, we constructed an artificial vascular tissue constructed by human adipose tissue-derived stromal cells (hASCs) and HUVECs (ASCVT) by a modified technique with cryopreservation. ASCVT showed a higher thickness with more dense vascular networks than the 3D tissue based on NHDFs. Correspondingly, 3D-cultured ASCs showed higher expression of several angiogenesis-related factors, including vascular endothelial growth factor-A and hepatic growth factor, compared to that of NHDFs. Moreover, perivascular cells in ASCVT were detected by pericyte markers, suggesting the differentiation of hASCs into pericyte-like cells. Subcutaneous transplantation of ASCVTs to nude mice resulted in an engraftment with anastomosis of host's vascular structures at 2 weeks after operation. In the engrafted tissue, the vascular network was surrounded by mural-like structure-forming hASCs, in which some parts developed to form vein-like structures at 4 weeks, suggesting the generation of functional vessel networks. These results demonstrated that cryopreserved human cells, including hASCs, could be used directly to construct the artificial transplantable tissue for regenerative medicine.

Combination of Stem Cells and Rehabilitation Therapies for Ischemic Stroke

Stem cell transplantation with rehabilitation therapy presents an effective stroke treatment. Here, we discuss current breakthroughs in stem cell research along with rehabilitation strategies that may have a synergistic outcome when combined together after stroke. Indeed, stem cell transplantation offers a promising new approach and may add to current rehabilitation therapies. By reviewing the pathophysiology of stroke and the mechanisms by which stem cells and rehabilitation attenuate this inflammatory process, we hypothesize that a combined therapy will provide better functional outcomes for patients. Using current preclinical data, we explore the prominent types of stem cells, the existing theories for stem cell repair, rehabilitation treatments inside the brain, rehabilitation modalities outside the brain, and evidence pertaining to the benefits of combined therapy. In this review article, we assess the advantages and disadvantages of using stem cell transplantation with rehabilitation to mitigate the devastating effects of stroke.

Long Term Response to Circulating Angiogenic Cells, Unstimulated or Atherosclerotic Pre-Conditioned, in Critical Limb Ischemic Mice

Critical limb ischemia (CLI), the most severe form of peripheral artery disease, results from the blockade of peripheral vessels, usually correlated to atherosclerosis. Currently, endovascular and surgical revascularization strategies cannot be applied to all patients due to related comorbidities, and even so, most patients require re-intervention or amputation within a year. Circulating angiogenic cells (CACs) constitute a good alternative as CLI cell therapy due to their vascular regenerative potential, although the mechanisms of action of these cells, as well as their response to pathological conditions, remain unclear. Previously, we have shown that CACs enhance angiogenesis/arteriogenesis from the first days of administration in CLI mice. Also, the incubation ex vivo of these cells with factors secreted by atherosclerotic plaques promotes their activation and mobilization. Herein, we have evaluated the long-term effect of CACs administration in CLI mice, whether pre-stimulated or not with atherosclerotic factors. Remarkably, mice receiving CACs and moreover, pre-stimulated CACs, presented the highest blood flow recovery, lower progression of ischemic symptoms, and decrease of immune cells recruitment. In addition, many proteins potentially involved, like CD44 or matrix metalloproteinase 9 (MMP9), up-regulated in response to ischemia and decreased after CACs administration, were identified by a quantitative proteomics approach. Overall, our data suggest that pre-stimulation of CACs with atherosclerotic factors might potentiate the regenerative properties of these cells in vivo.

Endothelial Progenitor Cells in Moyamoya Disease: Current Situation and Controversial Issues

Due to the lack of animal models and difficulty in obtaining specimens, the study of pathogenesis of moyamoya disease (MMD) almost stagnated. In recent years, endothelial progenitor cells (EPCs) have attracted more and more attention in vascular diseases due to their important role in neovascularization. With the aid of paradigms and methods in cardiovascular diseases research, people began to explore the role of EPCs in the processing of MMD. In the past decade, studies have shown that abnormalities in cell amounts and functions of EPCs were closely related to the vascular pathological changes in MMD. However, the lack of consistent criteria, such as isolation, cultivation, and identification standards, is also blocking the way forward. The goal of this review is to provide an overview of the current situation and controversial issues relevant to studies about EPCs in the pathogenesis and etiology of MMD.

The Role of NF-κB Triggered Inflammation in Cerebral Ischemia

Cerebral ischemia is a devastating disease that affects many people worldwide every year. The neurodegenerative damage as a consequence of oxygen and energy deprivation, to date, has no known effective treatment. The ischemic insult is followed by an inflammatory response that involves a complex interaction between inflammatory cells and molecules which play a role in the progression towards cell death. However, there is presently a matter of controversy over whether inflammation could either be involved in brain damage or be a necessary part of brain repair. The inflammatory response is triggered by inflammasomes, key multiprotein complexes that promote secretion of pro-inflammatory cytokines. An early event in post-ischemic brain tissue is the release of certain molecules and reactive oxygen species (ROS) from injured neurons which induce the expression of the nuclear factor-kappaB (NF-κB), a transcription factor involved in the activation of the inflammasome. There are conflicting observations related to the role of NF-κB. While some observe that NF-κB plays a damaging role, others suggest it to be neuroprotective in the context of cerebral ischemia, indicating the need for additional investigation. Here we discuss the dual role of the major inflammatory signaling pathways and provide a review of the latest research aiming to clarify the relationship between NF-κB mediated inflammation and neuronal death in cerebral ischemia.

Current status of cardiac regenerative medicine; An update on point of view to cell therapy application

Cardiovascular diseases (CVDs) are the leading cause of death globally. Because of the economic and social burden of acute myocardial infarction and its chronic consequences in surviving patients, understanding the pathophysiology of myocardial infarction injury is a major priority for cardiovascular research. MI is defined as cardiomyocytes death caused by an ischemic that resulted from the apoptosis, necrosis, necroptosis, and autophagy. The phases of normal repair following MI including inflammatory, proliferation, and maturation. Normal repair is slow and inefficient generally so that other treatments are required. Because of difficulties, outcomes, and backwashes of traditional therapies including coronary artery bypass grafting, balloon angioplasty, heart transplantation, and artificial heart operations, the novel strategy in the treatment of MI, cell therapy, was newly emerged. In cell therapy, a new population of cells has created that substitute with damaged cells. Different types of stem cell and progenitor cells have been shown to improve cardiac function through various mechanisms, including the formation of new myocytes, endothelial cells, and vascular smooth muscle cells. Bone marrow- and/or adipose tissue-derived mesenchymal stem cells, embryonic stem cells, autologous skeletal myoblasts, induced pluripotent stem cells, endothelial progenitor cells, cardiac progenitor cells and cardiac pericytes considered as a source for cell therapy. In this study, we focused on the point of view of the cell sources.

Clinical Translation of Cell Therapies in Stroke (CT2S) Checklist-a pragmatic tool to accelerate development of cell therapy products

BACKGROUND

Cell therapies present an exciting potential but there is a long history of expensive translational failures in stroke research. Researchers engaged in cell therapy research would benefit from a practical framework that can help in planning research and development of investigational cell therapies into viable medical products.

METHODS

We developed a checklist using a mixed methodology approach to evaluate the impact of study design, regulatory policy, ethical, and health economic considerations for efficient implementation of early phase cell therapy studies.

RESULTS

The checklist comprises a series of questions arranged under four domains: the first concerns study design such as characterization of target study population, trial design, endpoints and operational fit of dosage, time, and route of administration to target populations. A second domain addresses the data package required for regulatory approval relevant to the intended use (allogeneic/autologous; homologous/non-homologous; nature of cell processing). The third domain comprises patient involvement to ensure relevant data is collected via targeted study design. The final domain requires the team to determine the critical data elements that could be built into study design to enable health economic data collection to be started at an early phase of the study.

CONCLUSIONS

The CT2S checklist can help to determine areas of expertise gaps and enable research groups to appropriately allocate resources for capacity building. Use of this checklist will allow identification of key areas where trial planning needs to be optimized, as well as helping to identify resources that need to be secured. The CT2S checklist can also serve as a general cell therapy research decision aid to improve research output and accelerate new cell therapy development.

The secretome of endothelial progenitor cells: a potential therapeutic strategy for ischemic stroke

Ischemic stroke continues to be a leading cause of mortality and morbidity in the world. Despite recent advances in the field of stroke medicine, thrombolysis with recombinant tissue plasminogen activator remains as the only pharmacological therapy for stroke patients. However, due to short therapeutic window (4.5 hours of stroke onset) and increased risk of hemorrhage beyond this point, each year globally less than 1% of stroke patients receive this therapy which necessitate the discovery of safe and efficacious therapeutics that can be used beyond the acute phase of stroke. Accumulating evidence indicates that endothelial progenitor cells (EPCs), equipped with an inherent capacity to migrate, proliferate and differentiate, may be one such therapeutics. However, the limited availability of EPCs in peripheral blood and early senescence of few isolated cells in culture conditions adversely affect their application as effective therapeutics. Given that much of the EPC-mediated reparative effects on neurovasculature is realized by a wide range of biologically active substances released by these cells, it is possible that EPC-secretome may serve as an important therapeutic after an ischemic stroke. In light of this assumption, this review paper firstly discusses the main constituents of EPC-secretome that may exert the beneficial effects of EPCs on neurovasculature, and then reviews the currently scant literature that focuses on its therapeutic capacity.