Endothelial progenitor cells in acute ischemic stroke

Association of circulating CD34+ cells level and prognosis after ischemic stroke

BACKGROUND

CD34 is a transmembrane phosphoglycoprotein and a marker of hematopoietic and nonhematopoietic stem/progenitor cells. In experimental studies, CD34+ cells are rich sources of endothelial progenitor cells and can promote neovascularization and endothelial repair. The potential role of CD34+ cells in stroke patients remains unclear.

AIMS

We aimed to assess the prognostic effect of circulating CD34+ cell levels on the risk of vascular events and functional prognosis in stroke patients.

PATIENTS AND METHODS

In this prospective observational study, patients with ischemic stroke were consecutively enrolled within 1 week of onset and followed up for 1 year. Patients were divided into three groups according to tertiles of the level of circulating CD34+ cells (Tertile 1, <0.51/µL; Tertile 2, 0.51-0.96/µL; and Tertile 3, >0.96/µL). The primary outcome was a composite of major adverse cardiovascular events (MACEs), including nonfatal stroke, nonfatal acute coronary syndrome, major peripheral artery disease, and vascular death. The secondary outcomes included the modified Rankin scale (mRS) scores.

RESULTS

A total of 524 patients (mean age, 71.3 years; male, 60.1%) were included. High CD34+ cell levels were associated with younger age (p < 0.001) and low National Institutes of Health Stroke Scale scores at admission (p = 0.010). No significant differences were found in the risk of MACEs among the three groups (annual rates: 15.0%, 13.4%, and 12.6% in Tertiles 1, 2, and 3, respectively; log-rank p = 0.70). However, there were significant differences in the mRS scores at 3 months (median (interquartile range); 2 (1-4), 1 (1-3), and 1 (0-2) in Tertiles 1, 2, and 3, respectively; p = 0.010) and 1 year (3 (1-4), 2 (1-4), and 1 (0-3); p < 0.001) among these groups. After multivariable adjustments, a higher CD34+ cell level was independently associated with good functional outcomes (mRS score of 0-2) at 3 months (adjusted odds ratio (OR), 1.43; 95% confidence interval (CI), 1.01-2.05) and 1 year (adjusted OR, 1.53; 95% CI, 1.09-2.16).

CONCLUSION

Although no correlations were found between circulating CD34+ cell levels and vascular event risk, elevated CD34+ cell levels were associated with favorable functional recovery in stroke patients.

DATA ACCESS STATEMENT

Data supporting the findings of this study are available from the corresponding author on reasonable request.

CLINICAL TRIAL REGISTRATION

The TWMU Stroke Registry is registered at https://upload.umin.ac.jp as UMIN000031913.

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.

Impairment of muscular endothelial cell regeneration in dermatomyositis

Background and aim

Inflammatory myopathies are heterogeneous in terms of etiology, (immuno)pathology, and clinical findings. Endothelial cell injury, as it occurs in DM, is a common feature of numerous inflammatory and non-inflammatory vascular diseases. Vascular regeneration is mediated by both local and blood-derived mechanisms, such as the mobilization and activation of so-called proangiogenic cells (PACs) or early endothelial progenitor cells (eEPCs). The current study aimed to evaluate parameters of eEPC integrity in dermatomyositis (DM), compared to necrotizing myopathy (NM) and to non-myopathic controls.

Methods

Blood samples from DM and NM patients were compared to non-myositis controls and analyzed for the following parameters: circulating CD133⁺/VEGFR-2⁺ cells, number of colony-forming unit endothelial cells (CFU-ECs), concentrations of angiopoietin 1, vascular endothelial growth factor (VEGF), and CXCL-16. Muscle biopsies from DM and NM subjects underwent immunofluorescence analysis for CXCR6, nestin, and CD31 (PECAM-1). Finally, myotubes, derived from healthy donors, were stimulated with serum samples from DM and NM patients, subsequently followed by RT-PCR for the following candidates: IL-1β, IL-6, nestin, and CD31.

Results

Seventeen (17) DM patients, 7 NM patients, and 40 non-myositis controls were included. CD133⁺/VEGFR-2⁺ cells did not differ between the groups. Both DM and NM patients showed lower CFU-ECs than controls. In DM, intramuscular CD31 abundances were significantly reduced, which indicated vascular rarefaction. Muscular CXCR6 was elevated in both diseases. Circulating CXCL-16 was higher in DM and NM in contrast, compared to controls. Serum from patients with DM but not NM induced a profound upregulation of mRNS expression of CD31 and IL-6 in cultured myotubes.

Conclusion

Our study demonstrates the loss of intramuscular microvessels in DM, accompanied by endothelial activation in DM and NM. Vascular regeneration was impaired in DM and NM. The findings suggest a role for inflammation-associated vascular damage in the pathogenesis of DM.

Unraveling the potential of endothelial progenitor cells as a treatment following ischemic stroke

Ischemic stroke is becoming one of the most common causes of death and disability in developed countries. Since current therapeutic options are quite limited, focused on acute reperfusion therapies that are hampered by a very narrow therapeutic time window, it is essential to discover novel treatments that not only stop the progression of the ischemic cascade during the acute phase, but also improve the recovery of stroke patients during the sub-acute or chronic phase. In this regard, several studies have shown that endothelial progenitor cells (EPCs) can repair damaged vessels as well as generate new ones following cerebrovascular damage. EPCs are circulating cells with characteristics of both endothelial cells and adult stem cells presenting the ability to differentiate into mature endothelial cells and self-renew, respectively. Moreover, EPCs have the advantage of being already present in healthy conditions as circulating cells that participate in the maintenance of the endothelium in a direct and paracrine way. In this scenario, EPCs appear as a promising target to tackle stroke by self-promoting re-endothelization, angiogenesis and vasculogenesis. Based on clinical data showing a better neurological and functional outcome in ischemic stroke patients with higher levels of circulating EPCs, novel and promising therapeutic approaches would be pharmacological treatment promoting EPCs-generation as well as EPCs-based therapies. Here, we will review the latest advances in preclinical as well as clinical research on EPCs application following stroke, not only as a single treatment but also in combination with new therapeutic approaches.

Endothelial Progenitor Cells Count after Acute Ischemic Stroke Predicts Functional Outcome in Patients with Carotid Atherosclerosis

OBJECTIVES

Circulating Endothelial Progenitor Cells (EPCs) predict cardiovascular outcomes in patients with coronary disease. However, the predictive value of EPCs after ischemic stroke is not well established. We aimed to study the prognostic role of EPCs in patients with acute ischemic stroke and carotid atherosclerosis, focusing on post-stroke functional outcome and stroke recurrences.

MATERIALS AND METHODS

We studied consecutive adult patients with an acute (<7 days) anterior circulation ischemic stroke and carotid atherosclerosis. Cardioembolic strokes were excluded. We measured circulating EPCs by flow cytometry (CD34+/CD133+/KDR+) at inclusion (7±1 days after stroke) and at one year of follow-up. At three months and at one year we registered the modified Rankin Scale score, stroke recurrences and coronary syndromes during the follow-up.

RESULTS

We studied 80 patients with a mean age of 74.3±10.4 years. We divided the population in tertiles according to the EPCs count. At three months we observed a favorable outcome in 25/36 (69.4%) patients in the lowest, 19/22 (86.4%) in the medium and 21/22 (95.5%) in the highest tercile (p=0.037). In the multivariable analysis a higher EPCs count was associated with favorable functional outcome after adjusting for age and baseline NIHSS score (OR=3.61, 95%CI 1.34-9.76; p=0.011). This association persisted at one year of follow-up. We did not find association between counts of EPCs and stroke recurrence.

CONCLUSIONS

In patients with acute ischemic stroke and carotid atherosclerosis, a higher count of EPCs was associated with favorable functional outcome in the mid and long-term follow-up. Counts of EPCs did not predict stroke recurrences.

Role of Stromal Cell-Derived Factor-1 in Endothelial Progenitor Cell-Mediated Vascular Repair and Regeneration

Endothelial progenitor cells (EPCs) are immature endothelial cells that participate in vascular repair and postnatal neovascularization and provide a novel and promising therapy for the treatment of vascular disease. Studies in different animal models have shown that EPC mobilization through pharmacological agents and autologous EPC transplantation contribute to restoring blood supply and tissue regeneration after ischemic injury. However, these effects of the progenitor cells in clinical studies exhibit mixed results. The therapeutic efficacy of EPCs is closely associated with the number of the progenitor cells recruited into ischemic regions and their functional abilities and survival in injury tissues. In this review, we discussed the regulating role of stromal cell-derived factor-1 (also known CXCL12, SDF-1) in EPC mobilization, recruitment, homing, vascular repair and neovascularization, and analyzed the underlying machemisms of these functions. Application of SDF-1 to improve the regenerative function of EPCs following vascular injury was also discussed. SDF-1 plays a crucial role in mobilizing EPC from bone marrow into peripheral circulation, recruiting the progenitor cells to target tissue and protecting against cell death under pathological conditions; thus improve EPC regenerative capacity. SDF-1 are crucial for regulating EPC regenerative function, and provide a potential target for improve therapeutic efficacy of the progenitor cells in treatment of vascular disease.

Neovascularization and tissue regeneration by endothelial progenitor cells in ischemic stroke

Endothelial progenitor cells (EPCs) are immature endothelial cells (ECs) capable of proliferating and differentiating into mature ECs. These progenitor cells migrate from bone marrow (BM) after vascular injury to ischemic areas, where they participate in the repair of injured endothelium and new blood vessel formation. EPCs also secrete a series of protective cytokines and growth factors that support cell survival and tissue regeneration. Thus, EPCs provide novel and promising potential therapies to treat vascular disease, including ischemic stroke. However, EPCs are tightly regulated during the process of vascular repair and regeneration by numerous endogenous cytokines that are associated closely with the therapeutic efficacy of the progenitor cells. The regenerative capacity of EPCs also is affected by a range of exogenous factors and drugs as well as vascular risk factors. Understanding the functional properties of EPCs and the factors related to their regenerative capacity will facilitate better use of these progenitor cells in treating vascular disease. Here, we review the current knowledge of EPCs in cerebral neovascularization and tissue regeneration after cerebral ischemia and the factors associated with their regenerative function to better understand the underlying mechanisms and provide more effective strategies for the use of EPCs in treating ischemic stroke.

Influence of metabolic syndrome on post-stroke outcome, angiogenesis and vascular function in old rats determined by dynamic contrast enhanced MRI

Stroke affects primarily aged and co-morbid people, aspects not properly considered to date. Since angiogenesis/vasculogenesis are key processes for stroke recovery, we purposed to determine how different co-morbidities affect the outcome and angiogenesis/vasculogenesis, using a rodent model of metabolic syndrome, and by dynamic enhanced-contrast imaging (DCE-MRI) to assess its non-invasive potential to determine these processes. Twenty/twenty-two month-old corpulent (JCR:LA-Cp/Cp), a model of metabolic syndrome and lean rats were used. After inducing the experimental ischemia by transient MCAO, angiogenesis was analyzed by histology, vasculogenesis by determination of endothelial progenitor cells in peripheral blood by flow cytometry and evaluating their pro-angiogenic properties in culture and the vascular function by DCE-MRI at 3, 7 and 28 days after tMCAO. Our results show an increased infarct volume, BBB damage and an impaired outcome in corpulent rats compared with their lean counterparts. Corpulent rats also displayed worse post-stroke angiogenesis/vasculogenesis, outcome that translated in an impaired vascular function determined by DCE-MRI. These data confirm that outcome and angiogenesis/vasculogenesis induced by stroke in old rats are negatively affected by the co-morbidities present in the corpulent genotype and also that DCE-MRI might be a technique useful for the non-invasive evaluation of vascular function and angiogenesis processes.

Exosomes Derived from CXCR4-Overexpressing BMSC Promoted Activation of Microvascular Endothelial Cells in Cerebral Ischemia/Reperfusion Injury

Background

Ischemic stroke is a severe acute cerebrovascular disease which can be improved with neuroprotective therapies at an early stage. However, due to the lack of effective neuroprotective drugs, most stroke patients have varying degrees of long-term disability. In the present study, we investigated the role of exosomes derived from CXCR4-overexpressing BMSCs in restoring vascular function and neural repair after ischemic cerebral infarction.

Methods

BMSCs were transfected with lentivirus encoded by CXCR4 (BMSC^CXCR4). Exosomes derived from BMSC^CXCR4 (Exo^CXCR4) were isolated and characterized by transmission electron microscopy and dynamic light scattering. Western blot and qPCR were used to analyze the expression of CXCR4 in BMSCs and exosomes. The acute middle cerebral artery occlusion (MCAO) model was prepared, Exo^CXCR4 were injected into the rats, and behavioral changes were analyzed. The role of Exo^CXCR4 in promoting the proliferation and tube formation for angiogenesis and protecting brain endothelial cells was determined in vitro.

Results

Compared with the control groups, the Exo^CXCR4 group showed a significantly lower mNSS score at 7 d, 14 d, and 21 d after ischemia/reperfusion (P < 0.05). The bEnd.3 cells in the Exo^CXCR4 group have stronger proliferation ability than other groups (P < 0.05), while the CXCR4 inhibitor can reduce this effect. Exosomes control (Exo^Con) can significantly promote the migration of bEnd.3 cells (P < 0.05), while there was no significant difference between the Exo^CXCR4 and Exo^Con groups (P > 0.05). Exo^CXCR4 can further promote the proliferation and tube formation for the angiogenesis of the endothelium compared with Exo^Con group (P < 0.05). In addition, cobalt chloride (COCl2) can increase the expression of β-catenin and Wnt-3, while Exo^Con can reduce the expression of these proteins (P < 0.05). Exo^CXCR4 can further attenuate the activation of Wnt-3a/β-catenin pathway (P < 0.05).

Conclusions

In ischemia/reperfusion injury, Exo^CXCR4 promoted the proliferation and tube formation of microvascular endothelial cells and play an antiapoptotic role via the Wnt-3a/β-catenin pathway.

Characterization and Functional Assessment of Endothelial Progenitor Cells in Ischemic Stroke Patients

Endothelial dysfunction has been implicated in atherosclerosis, ischemic heart disease, and stroke. Endothelial progenitor cells (EPCs), found in the bone marrow and peripheral blood as rare cell population, demonstrated a high proliferation and differentiation capacity. Understanding how such diseases influence the quantity and functionality of EPCs is essential for the development of novel therapies. This study aims to investigate the factors that affect the quantity and functionality of circulating EPCs in stroke patients and healthy controls. Blood samples were collected once from healthy donors (n = 30) and up to 3 times (within 7 days (baseline), 3 and 12 months post-stroke) from stroke patients (n = 207). EPC subpopulations were isolated with flow cytometry for characterization. The Matrigel tubular formation assay was performed as a measure of functionality. An increased amount of circulating EPCs was observed in stroke patients over 45 years when compared to age-matched healthy individuals. EPCs showed a rising trend in stroke patients over the 12-month post-stroke period, reaching statistical significance at 12 months post-stroke. Isolated CD34⁺KDR⁺ cells from stroke patients showed impairment in tubular formation capability when compared to cells from healthy donors. The quantity and vasculogenic function of circulating EPCs in peripheral blood have been effectively evaluated in stroke patients and healthy control donors in this study. Age and stroke are found to be 2 influencing factors on the angiogenic capacity. It is suggested that the increase in EPC number is triggered by the recovery response following ischemic stroke.

Endothelial Progenitor Cells as a Marker of Vascular Damage But not a Predictor in Acute Microangiopathy-Associated Stroke

Background: The aim of the study was to assess the number of endothelial progenitor cells (EPCs) in patients with acute stroke due to cerebral microangiopathy and evaluate whether there is a relationship between their number and clinical status, radiological findings, risk factors, selected biochemical parameters, and prognosis, both in ischemic and hemorrhagic stroke. Methods: In total, 66 patients with lacunar ischemic stroke, 38 patients with typical location hemorrhagic stroke, and 22 subjects from the control group without acute cerebrovascular incidents were included in the prospective observational study. The number of EPCs was determined in serum on the first and eighth day after stroke onset using flow cytometry and identified with the immune-phenotype classification determinant (CD)45−, CD34+, CD133+. Results: We demonstrated a significantly higher number of EPCs on the first day of stroke compared to the control group (med. 17.75 cells/µL (0–488 cells/µL) vs. 5.24 cells/µL (0–95 cells/µL); p = 0.0006). We did not find a relationship between the number of EPCs in the acute phase of stroke and the biochemical parameters, vascular risk factors, or clinical condition. In females, the higher number of EPCs on the first day of stroke is related to a favorable functional outcome on the eighth day after the stroke onset compared to males (p = 0.0355). We found that a higher volume of the hemorrhagic focus on the first day was correlated with a lower number of EPCs on the first day (correlation coefficient (R) = −0.3378, p = 0.0471), and a higher number of EPCs on the first day of the hemorrhagic stroke was correlated with a lower degree of regression of the hemorrhagic focus (R = −0.3896, p = 0.0367). Conclusion: The study showed that endothelial progenitor cells are an early marker in acute microangiopathy-associated stroke regardless of etiology and may affect the radiological findings in hemorrhagic stroke. Nevertheless, their prognostic value remains doubtful in stroke patients.

Endothelial Dysfunction May Link Interatrial Septal Abnormalities and MTHFR-Inherited Defects to Cryptogenic Stroke Predisposition

We explored the significance of the L-Arginine/asymmetric dimethylarginine (L-Arg/ADMA) ratio as a biomarker of endothelial dysfunction in stroke patients. To this aim, we evaluated the correlation, in terms of severity, between the degree of endothelial dysfunction (by L-Arg/ADMA ratio), the methylene tetrahydrofolate reductase (MTHFR) genotype, and the interatrial septum (IAS) phenotype in subject with a history of stroke. Methods and Results: L-Arg, ADMA, and MTHFR genotypes were evaluated; the IAS phenotype was assessed by transesophageal echocardiography. Patients were grouped according to the severity of IAS defects and the residual enzymatic activity of MTHFR-mutated variants, and values of L-Arg/ADMA ratio were measured in each subgroup. Of 57 patients, 10 had a septum integrum (SI), 38 a patent foramen ovale (PFO), and 9 an ostium secundum (OS). The L-Arg/ADMA ratio differed across septum phenotypes (p ≤ 0.01), and was higher in SI than in PFO or OS patients (p ≤ 0.05, p ≤ 0.01, respectively). In the PFO subgroup a negative correlation was found between the L-Arg/ADMA ratio and PFO tunnel length/height ratio (p ≤ 0.05; r = − 0.37; R2 = 0.14). Interestingly, the L-Arg/ADMA ratio varied across MTHFR genotypes (p ≤ 0.0001) and was lower in subgroups carrying the most impaired enzyme with respect to patients carrying the conservative MTHFR (p ≤ 0.0001, p ≤ 0.05, respectively). Consistently, OS patients carried the most dysfunctional MTHFR genotypes, whereas SI patients the least ones. Conclusions: A low L-Arg/ADMA ratio correlates with impaired activity of MTHFR and with the jeopardized IAS phenotype along a severity spectrum encompassing OS, PFO with long/tight tunnel, PFO with short/large tunnel, and SI. This infers that genetic MTHFR defects may underlie endothelial dysfunction-related IAS abnormalities, and predispose to a cryptogenic stroke. Our findings emphasize the role of the L-Arg/ADMA ratio as a reliable marker of stroke susceptibility in carriers of IAS abnormalities, and suggest its potential use both as a diagnostic tool and as a decision aid for therapy.

Harnessing the anti-inflammatory properties of stem cells for transplant therapy in hemorrhagic stroke

Hemorrhagic stroke is a global health crisis plagued by neuroinflammation in the acute and chronic phases. Neuroinflammation approximates secondary cell death, which in turn robustly contributes to stroke pathology. Both the physiological and behavioral symptoms of stroke correlate with various inflammatory responses in animal and human studies. That slowing the secondary cell death mediated by this inflammation may attenuate stroke pathology presents a novel treatment strategy. To this end, experimental therapies employing stem cell transplants support their potential for neuroprotection and neuroregeneration after hemorrhagic stroke. In this review, we evaluate experiments using different types of stem cell transplants as treatments for stroke-induced neuroinflammation. We also update this emerging area by examining recent preclinical and clinical trials that have deployed these therapies. While further investigations are warranted to solidify their therapeutic profile, the reviewed studies largely posit stem cells as safe and potent biologics for stroke, specifically owing to their mode of action for sequestering neuroinflammation and promoting neuroregenerative processes.

Endothelial progenitor cells, potential biomarkers for diagnosis and prognosis of ischemic stroke: protocol for an observational case-control study

Ischemic stroke is a devastating, life altering event which can severely reduce patient quality of life. Despite years of research there have been minimal therapeutic advances. Endothelial progenitor cells (EPCs), stem cells involved in both vasculogenesis and angiogenesis, may be a potential therapeutic target. After a stroke, EPCs migrate to the site of ischemic injury to repair cerebrovascular damage, and their numbers and functional capacity may determine patients’ outcome. This study aims to determine whether the number of circulating EPCs and their functional aspects may be used as biomarkers to identify the type (cortical or lacunar) and/or severity of ischemic stroke. The study will also investigate if there are any differences in these characteristics between healthy volunteers over and under 65 years of age. 100 stroke patients (50 lacunar and 50 cortical strokes) will be recruited in this prospective, observational case-controlled study. Blood samples will be taken from stroke patients at baseline (within 48 hours of stroke) and days 7, 30 and 90. EPCs will be counted with flow cytometry. The plasma levels of pro- and anti-angiogenic factors and inflammatory cytokines will also be determined. Outgrowth endothelial cells will be cultured to be used in tube formation, migration and proliferation functional assays. Primary outcome is disability or dependence on day 90 after stroke, assessed by the modified Rankin Scale. Secondary outcomes are changes in circulating EPC numbers and/or functional capacity between patient and healthy volunteers, between patient subgroups and between elderly and young healthy volunteers. Recruitment started in February 2017, 167 participants have been recruited. Recruitment will end in November 2019. West Midlands - Coventry & Warwickshire Research Ethics Committee approved this study (REC number: 16/WM/0304) on September 8, 2016. Protocol version: 2.0. The Bayraktutan Dunhill Medical Trust EPC Study was registered in ClinicalTrials.gov (NCT02980354) on November 15, 2016. This study will determine whether the number of EPCs can be used as a prognostic or diagnostic marker for ischemic strokes and is a step towards discovering if transplantation of EPCs may aid patient recovery.

Importance of Angiogenin and Endothelial Progenitor Cells After Rehabilitation Both in Ischemic Stroke Patients and in a Mouse Model of Cerebral Ischemia

Background: Rehabilitation therapy is the only available treatment for stroke survivors presenting neurological deficits; however, the underlying molecules and mechanisms associated with functional/motor improvement during rehabilitation are poorly understood. Objective: Our aim is to study the modulation of angiogenin and endothelial progenitor cells (EPCs) as repair-associated factors in a cohort of stroke patients and mouse models of rehabilitation after cerebral ischemia. Methods: The clinical study included 18 ischemic strokes admitted to an intensive rehabilitation therapy (IRT) unit, 18 non-ischemic controls and brain samples from three deceased patients. Angiogenin and EPCs were measured in blood obtained before and up to 6 months after IRT together with an extensive evaluation of the motor/functional status. In parallel, C57BL/6 mice underwent middle cerebral artery occlusion, and the pasta matrix reaching-task or treadmill exercises were used as rehabilitation models. Angiogenin RNA expression was measured after 2 or 12 days of treatment together with cell counts from EPCs cultures. Results: Brain angiogenin was identified in both human and mouse tissue, whereas serum levels increased after 1 month of IRT in association with motor/functional improvement. EPC populations were increased after stroke and remained elevated during follow-up after IRT. The mouse model of rehabilitation by the task-specific pasta matrix exercise increased the number of EPCs at 2 days and increased angiogenin expression after 12 days of rehabilitation. Conclusions: Angiogenin and EPCs are modulated by rehabilitation after cerebral ischemia, suggesting that both angiogenin and EPCs could serve as biomarkers of improvement during rehabilitation or future therapeutic targets.

Cell-Based Therapies in Acute Kidney Injury (AKI)

Acute kidney injury frequently occurs in hospitalized patients all over the world. The prognosis remains poor since specific therapies for promoting kidney regeneration/repair are still missing. In recent years cell-based strategies have improved AKI outcomes under experimental circumstances. Four groups of cells, each of them displaying certain biological and functional characteristics have been evaluated in AKI, induced Pluripotent Stem Cells (iPSCs), Spermatagonial Stem Cells (SSCs), Proangiogenic Cells (PACs) and Endothelial Colony Forming Cells (ECFCs), and Mesenchymal Stem Cells (MSCs). All of these have been documented to stabilize either parameters of kidney excretory dysfunction and/or certain morphological parameters. The mechanisms responsible for AKI protection include direct (cell incorporation) and indirect processes, the latter being mediated by humoral factors and particularly by the production of so-called extracellular vesicles. Cell-derived vesicular organelles have been shown to carry pro-regenerative micro-RNA molecules which stabilize the vascular and tubular function. The first trials in humans have been initiated, the majority of such trials employs MSCs. However, any transfer of cell-based strategies in the clinical practice is potentially associated with significant difficulties. These include cell availability, tolerance and competence. The article intends to summarize essential informations about all of the four populations mentioned above and to discuss implications for the management of human AKI.

Effects of Angiotensin-Converting Enzyme Inhibition on Circulating Endothelial Progenitor Cells in Patients with Acute Ischemic Stroke

Background

Therapeutic neovascularization might represent an important strategy to salvage tissue after ischemia. Circulating bone marrow-derived endothelial progenitor cells (EPCs) were previously shown to augment the neovascularization of ischemic tissue. Angiotensin-converting enzyme inhibitors (ACEIs) might modulate EPC mobilization. We evaluated populations of circulating stem cells and early EPCs in acute ischemic stroke (AIS) patients and the effect of ACEI on circulating EPCs in these patients with respect to aspects of stroke pathogenesis.

Methods

We studied 43 AIS patients (group I), comprising 33 treated with ACEI (group Ia) and 10 untreated (group Ib). Risk factor controls (group II) included 22 subjects. EPCs were measured by flow cytometry.

Results

In AIS patients, the number of circulating stem cells and early EPCs upon admission was similar to that in control group individuals. There were no significant differences in the numbers of stem cells and early EPCs over subsequent days after AIS. There were also no significant differences in stem cell and early EPC numbers over the first 3 days between group Ia and group Ib. However, on day 7, these numbers were significantly higher in group Ib than in group Ia (p < 0.05). In AIS patients chronically treated with ACEI, there was a negative correlation between CD133⁺ cell number and neurological deficit on the first, third, and seventh days (p < 0.005).

Conclusions

An increased number of circulating stem cells and early EPCs were not observed in stroke patients chronically treated with ACEI. In patients chronically treated with ACEI, a significant correlation was observed between decreased neurological deficit and higher levels of CD133⁺ cells; this could be due to the positive influence of these cells on the regeneration of the endothelium and improved circulation in the ischemic penumbra.

Adult Stem Cells in Vascular Remodeling

Understanding the contribution of vascular cells to blood vessel remodeling is critical for the development of new therapeutic approaches to cure cardiovascular diseases (CVDs) and regenerate blood vessels. Recent findings suggest that neointimal formation and atherosclerotic lesions involve not only inflammatory cells, endothelial cells, and smooth muscle cells, but also several types of stem cells or progenitors in arterial walls and the circulation. Some of these stem cells also participate in the remodeling of vascular grafts, microvessel regeneration, and formation of fibrotic tissue around biomaterial implants. Here we review the recent findings on how adult stem cells participate in CVD development and regeneration as well as the current state of clinical trials in the field, which may lead to new approaches for cardiovascular therapies and tissue engineering.

Adjudin-preconditioned neural stem cells enhance neuroprotection after ischemia reperfusion in mice

BACKGROUND

Transplantation of neural stem cells (NSCs) has been proposed as a promising therapeutic strategy for the treatment of ischemia/reperfusion (I/R)-induced brain injury. However, existing evidence has also challenged this therapy on its limitations, such as the difficulty for stem cells to survive after transplantation due to the unfavorable microenvironment in the ischemic brain. Herein, we have investigated whether preconditioning of NSCs with adjudin, a small molecule compound, could enhance their survivability and further improve the therapeutic effect for NSC-based stroke therapy.

METHOD

We aimed to examine the effect of adjudin pretreatment on NSCs by measuring a panel of parameters after their transplantation into the infarct area of ipsilateral striatum 24 hours after I/R in mice.

RESULTS

We found that pretreatment of NSCs with adjudin could enhance the viability of NSCs after their transplantation into the stroke-induced infarct area. Compared with the untreated NSC group, the adjudin-preconditioned group showed decreased infarct volume and neurobehavioral deficiency through ameliorating blood-brain barrier disruption and promoting the expression and secretion of brain-derived neurotrophic factor. We also employed H2O2-induced cell death model in vitro and found that adjudin preconditioning could promote NSC survival through inhibition of oxidative stress and activation of Akt signaling pathway.

CONCLUSION

This study showed that adjudin could be used to precondition NSCs to enhance their survivability and improve recovery in the stroke model, unveiling the value of adjudin for stem cell-based stroke therapy.

Regulatory effects of miR-146a/b on the function of endothelial progenitor cells in acute ischemic stroke in mice

The study aims to explore how microRNA-146a/b (miR-146a/b) regulates the function of endothelial progenitor cells (EPCs) in acute ischemic stroke in mice. Eighty male SPF C57BL/6J mice were evenly divided into the model-6 h, model-12 h, model-24 h (mice suffered from middle cerebral artery occlusion [MCAO] for 6 h, 12 h and model-24 h) and normal groups. EPCs were transfected and assigned into the control, MCAO, MCAO-miR-146a, MCAO-miR-146b and MCAO-miR-146a/b groups. The qRT-PCR was used to detect miR-146a/b expression in EPCs. Expressions of tumor necrosis factor receptor-associated factor 6 (TRAF6) and interleukin-1 receptor-associated kinase 1 (IRAK1) were detected using western blotting. Cell proliferation and migration of EPCs were testified using CCK-8 assay and scratch test, respectively. Angiogenesis ability of EPCs was observed under microscope. MiR-146a and miR-146b expressions were lower in the model groups than the normal group. There were up-regulated TRAF6 and IRAK1 expressions in the model-6 h, model-12 h and model-24 h groups compared with the normal group. And there were down-regulated TRAF6 and IRAK1 expressions in the MCAO-miR-146a, MCAO-miR-146b and MCAO-miR-146a/b groups than in the MCAO group. Compared with the control group, the proliferation, migration and angiogenesis ability of EPCs were significantly lower in the MCAO group, but higher in the MCAO-miR-146a, MCAO-miR-146b and MCAO-miR-146a/b groups. Besides, the miR-146a/b group showed more enhancement than the MCAO-miR-146a and MCAO-miR-146b groups. MiR-146a/b could down-regulate the TRAF6 and IRAK1 expressions and promote proliferation, migration and angiogenesis ability of EPCs, which was important for recovery of patients with hyperacute ischemic stroke.

Vascular precursor cells in tissue injury repair

Vascular precursor cells include stem cells and progenitor cells giving rise to all mature cell types in the wall of blood vessels. When tissue injury occurs, local hypoxia and inflammation result in the generation of vasculogenic mediators which orchestrate migration of vascular precursor cells from their niche environment to the site of tissue injury. The intricate crosstalk among signaling pathways coordinates vascular precursor cell proliferation and differentiation during neovascularization. Establishment of normal blood perfusion plays an essential role in the effective repair of the injured tissue. In recent years, studies on molecular mechanisms underlying the regulation of vascular precursor cell function have achieved substantial progress, which promotes exploration of vascular precursor cell-based approaches to treat chronic wounds and ischemic diseases in vital organ systems. Verification of safety and establishment of specific guidelines for the clinical application of vascular precursor cell-based therapy remain major challenges in the field.

Changes in serum vascular endothelial growth factor and endostatin concentrations associated with circulating endothelial progenitor cells after acute ischemic stroke

Angiogenesis is an important pathophysiological response to cerebral ischemia, and can be modulated by vascular endothelial growth factor (VEGF) and endostatin. Circulating endothelial progenitor cells (EPCs) also play an important role as an endogenous repair mechanism for ischemic injury. We sought to investigate early changes in the expression of VEGF and endostatin in serum and the circulating EPCs in patients with acute ischemic stroke (AIS) and analyzed the relations between them. The peripheral blood and serum samples were obtained from 30 patients at 1, 3, 5 and 7 d after AIS. Flow cytometry was used to quantify EPCs, and VEGF and endostatin were measured by enzyme linked immunosorbent assay. Correlation analysis was performed to assess the relations between them. Receiver operating characteristic (ROC) curve was used to appraise the value of EPCs levels in predicting the 90-day prognosis after AIS. Compared with control subjects, circulating EPCs numbers increased from a very lower initial level (P < 0.001) until 7 d after AIS. Serum VEGF and endostatin levels increased and peaked at 3 d and 5 d post-stroke (both P < 0.001), respectively. A significant correlation (P = 0.001) was found between peak serum VEGF concentration and peak endostatin concentration. VEGF/endostatin ratio at day 1 and day 3 after AIS significantly correlated with circulating EPCs numbers at day 5 (P < 0.001) and day 7 post-stroke (P < 0.001). ROC curve analysis suggested that circulating EPCs number at day 7 had a significantly predictive power for good prognosis. VEGF and endostatin may mediate EPCs proliferation in the early phase of ischemic stroke, and the circulating EPCs levels can be a predictor of clinical outcome in AIS.

Correlation of Plasma Vascular Endothelial Growth Factor and Endostatin Levels with Symptomatic Intra- and Extracranial Atherosclerotic Stenosis in a Chinese Han Population

BACKGROUND

Symptomatic intracranial atherosclerotic stenosis (ICAS) and extracranial atherosclerotic stenosis (ECAS) are different in many aspects. Here, we explored the association between the location or severity of atherosclerotic stenosis and pro- or antiangiogenic factors, specifically vascular endothelial growth factor (VEGF) and endostatin (ES).

METHODS

We evaluated 198 consecutive patients with acute ischemia stroke: 132 with large-artery atherosclerosis (LAA) and 66 with small-artery occlusion (small-vessel occlusion). The LAA group was subclassified into 102 patients with ICAS and 30 with ECAS. Independent associations of VEGF, ES levels, and VEGF/ES ratio with the location of cerebral stenosis and the severity or short-term prognosis (14th day modified Rankin Scale) of ICAS were evaluated.

RESULTS

Plasma concentrations of VEGF and ES were lower (P < .05) in ICAS (38.07, 32.76-46.28 pg/mL and 58.95, 55.04-59.77 ng/mL) than those in ECAS (45.00, 34.30-83.34 pg/mL and 140.74, 85.63-231.21 ng/mL). Logistic regression analysis showed that VEGF concentrations and dyslipidemia were independently associated with ICAS, with odds ratios of .987 [95% CI = (.976, .998)] and .265 [95% CI = (.103, .792)], respectively. Moreover, plasmatic VEGF levels increased gradually along with the severity of ICAS (P = .003), and lower levels of ES (P = .040) or a higher VEGF/ES ratio (P = .048) were related to unfavorable short-term prognosis of ICAS.

CONCLUSION

Lower VEGF levels are associated with the presence of symptomatic ICAS, but not with ECAS. Furthermore, the severity of ICAS is positively correlated with the levels of VEGF, and lower ES levels or a predominance of VEGF over ES are predictors of poor short-term prognosis of ICAS.

Early Endothelial Progenitor Cells (eEPCs) in systemic sclerosis (SSc) - dynamics of cellular regeneration and mesenchymal transdifferentiation

BACKGROUND

Patients with systemic sclerosis (SSc) are endagered by tissue fibrosis and by microvasculopathy, with the latter caused by endothelial cell expansion/proliferation. SSc-associated fibrosis potentially results from mesenchymal transdifferentiation of endothelial cells. Early Endothelial Progenitor Cells (eEPCs) act proangiogenic under diverse conditions. Aim of the study was to analyze eEPC regeneration and mesenchymal transdifferentiation in patients with limited and diffuse SSs (lSSc and dSSc).

METHODS

Patients with both, lSSc and dSSc were included into the study. The following parameters were evaluated: eEPC numbers and regeneration, concentrations of vasomodulatory mediators, mesenchymal properties of blood-derived eEPC. Serum samples of healthy subjects and SS patients were used for stimulation of cultured human eEPC, subsequently followed by analysis of mesenchymal cell characteristics and mobility.

RESULTS

Twenty-nine patients were included into the study. Regenerative activity of blood-derived eEPCs did not differ between Controls and patients. Circulating eEPC were significantly lower in all patients with SSc, and in limited and diffuse SSc (lSSc/dSSc). Serum concentrations of promesenchymal TGF-b was elevated in all patients with SSc. Cultured mononuclear cells from SS patients displayed higher abundances of CD31 and of CD31 and aSMA combined. Finally, serum from SSc patients inhibited migration of cultured eEPCs and the cells showed lower sensitivity towards the endothelin antagonist Bosentan.

CONCLUSIONS

The eEPC system, which represents an essential element of the endogenous vascular repair machinery is affected in SSc. The increased appearance of mesenchymal properties in eEPC may indicate that alterations of the cells potentially contribute to the accumulation of connective tissue and to vascular malfunction.

Increased Endothelial Progenitor Cell Levels are Associated with Good Outcome in Intracerebral Hemorrhage

Circulating endothelial progenitor cells (EPCs) play a role in the regeneration of damaged brain tissue. However, the relationship between circulating EPC levels and functional recovery in intracerebral hemorrhage (ICH) has not yet been tested. Therefore, our aim was to study the influence of circulating EPCs on the outcome of ICH. Forty-six patients with primary ICH (males, 71.7%; age, 72.7 ± 10.8 years) were prospectively included in the study within 12 hours of symptom onset. The main outcome variable was good functional outcome at 12 months (modified Rankin scale ≤2), considering residual volume at 6 months as a secondary variable. Circulating EPC (CD34⁺/CD133⁺/KDR⁺) levels were measured by flow cytometry from blood samples obtained at admission, 72 hours and day 7. Our results indicate that patients with good outcome show higher EPC numbers at 72 hours and day 7 (all p < 0.001). However, only EPC levels at day 7 were independently associated with good functional outcome at 12 months (OR, 1.15; CI95%, 1.01–1.35) after adjustment by age, baseline stroke severity and ICH volume. Moreover, EPC levels at day 7 were negatively correlated to residual volume (r = −0.525; p = 0.005). In conclusion, these findings suggest that EPCs may play a role in the functional recovery of ICH patients.

Targeting brain microvascular endothelial cells: a therapeutic approach to neuroprotection against stroke

Brain microvascular endothelial cells form the interface between nervous tissue and circulating blood, and regulate central nervous system homeostasis. Brain microvascular endothelial cells differ from peripheral endothelial cells with regards expression of specific ion transporters and receptors, and contain fewer fenestrations and pinocytotic vesicles. Brain microvascular endothelial cells also synthesize several factors that influence blood vessel function. This review describes the morphological characteristics and functions of brain microvascular endothelial cells, and summarizes current knowledge regarding changes in brain microvascular endothelial cells during stroke progression and therapies. Future studies should focus on identifying mechanisms underlying such changes and developing possible neuroprotective therapeutic interventions.

Cellular connections, microenvironment and brain angiogenesis in diabetes: Lost communication signals in the post-stroke period

Diabetes not only increases the risk but also worsens the motor and cognitive recovery after stroke, which is the leading cause of disability worldwide. Repair after stroke requires coordinated communication among various cell types in the central nervous system as well as circulating cells. Vascular restoration is critical for the enhancement of neurogenesis and neuroplasticity. Given that vascular disease is a major component of all complications associated with diabetes including stroke, this review will focus on cellular communications that are important for vascular restoration in the context of diabetes. This article is part of a Special Issue entitled SI: Cell Interactions In Stroke.

Circulating endothelial progenitor cells and the risk of vascular events after ischemic stroke

Background and Purpose

We evaluated the hypothesis that the number of circulating EPC could be associated with the risk of stroke recurrence (SR) or vascular events (VE) after an ischemic stroke.

Methods

We studied prospectively consecutive patients with cerebral infarction within the first 48 hours after the onset. We recorded demographic factors, vascular risk factors, previous Rankin scale (RS) score, and etiology. We analyzed EPC counts by flow cytometry in blood collected at day 7 and defined EPC as CD34+/CD133+/KDR+ cells. Mean follow-up was 29.3 ± 16 months. We evaluated SR as well as VE. Patients were classified as to the presence or absence of EPC in the circulation (either EPC+ or EPC-). Bivariate analyses, Kaplan-Meier survival curves and Cox regression models were used.

Results

We included 121 patients (mean age 70.1±12.6 years; 65% were men). The percentage of EPC+ patients was 47.1%. SR occurred in 12 (9.9%) and VE in 18 (14.9%) patients. SR was associated significantly with a worse prior RS score, previous stroke and etiology, but not with EPC count. VE were associated significantly with EPC-, worse prior RS score, previous stroke, high age, peripheral artery disease and etiology. Cox regression model showed that EPC- (HR 7.07, p=0.003), age (HR 1.08, p=0.004) and a worse prior RS score (HR 5.8, p=0.004) were associated significantly with an increased risk of VE.

Conclusions

The absence of circulating EPC is not associated with the risk of stroke recurrence, but is associated with an increased risk of future vascular events.

Poor outcome of experimental ischemic stroke in type 2 diabetic rats: impaired circulating endothelial progenitor cells mobilization

BACKGROUND

It is well accepted that type 2 diabetic mellitus (T2DM) results in the poor outcome of ischemic stroke. However, the mechanisms by which T2DM causes aggravated cerebral ischemic/reperfusion (I/R) injury are not clear. Recently, endothelial progenitor cells (EPCs) are considered to be related with the outcome of ischemic stroke. More importantly, T2DM can affect the function of circulating EPCs. This study tried to investigate whether T2DM worsens the cerebral I/R injury via affecting circulating EPCs.

METHODS

We used high-fat diet-fed and low-dose streptozotocin-treated male rats receiving middle cerebral artery occlusion surgery as animal model of focal cerebral I/R injury with T2DM (diabetic operated). And the rats were divided into 4 groups: normal sham, diabetic sham, normal operated, and diabetic operated. We measured the circulating EPCs counts and the levels of vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) in peripheral plasma of 4 groups.

RESULTS

We found that diabetic rats subjected to I/R exhibited significantly severe deterioration in neurologic deficits compared with nondiabetic counterparts, which manifested higher infarct volume and cell apoptosis as well as lower neurologic defective score. There was no significant difference on the plasma glucose of groups before cerebral I/R injury compared with that of the groups posterior to cerebral I/R injury despite cerebral I/R injury had the tendency to increase the plasma glucose no matter in the presence or the absence of T2DM. In addition, there were the marked downregulation of circulating EPCs counts and the levels of VEGF and eNOS in diabetic rats before the cerebral I/R injury. Despite I/R injury without T2DM, there was a significant increase in the circulating EPCs counts, the circulating EPCs counts in I/R injury with T2DM group were significantly decreased compared with those in the other 3 groups. We also observed that the level of eNOS was significantly improved by I/R injury without considering the presence of T2DM.

CONCLUSIONS

Thus, our present study suggested that it might be the impaired EPCs mobilization into the blood that contributed to the worse outcome of cerebral I/R injury with T2DM.