Bone Marrow-derived Endothelial Progenitor Cells Research Articles

Translational Research of the Acute Effects of Negative Emotions on Vascular Endothelial Health: Findings From a Randomized Controlled Study.

Provoked anger is associated with an increased risk of cardiovascular disease events. The underlying mechanism linking provoked anger as well as other core negative emotions including anxiety and sadness to cardiovascular disease remain unknown. The study objective was to examine the acute effects of provoked anger, and secondarily, anxiety and sadness on endothelial cell health. Apparently healthy adult participants (n=280) were randomized to an 8-minute anger recall task, a depressed mood recall task, an anxiety recall task, or an emotionally neutral condition. Pre-/post-assessments of endothelial health including endothelium-dependent vasodilation (reactive hyperemia index), circulating endothelial cell-derived microparticles (CD62E+, CD31+/CD42-, and CD31+/Annexin V+) and circulating bone marrow-derived endothelial progenitor cells (CD34+/CD133+/kinase insert domain receptor+ endothelial progenitor cells and CD34+/kinase insert domain receptor+ endothelial progenitor cells) were measured. There was a group×time interaction for the anger versus neutral condition on the change in reactive hyperemia index score from baseline to 40 minutes (P=0.007) with a mean±SD change in reactive hyperemia index score of 0.20±0.67 and 0.50±0.60 in the anger and neutral conditions, respectively. For the change in reactive hyperemia index score, the anxiety versus neutral condition group by time interaction approached but did not reach statistical significance (P=0.054), and the sadness versus neutral condition group by time interaction was not statistically significant (P=0.160). There were no consistent statistically significant group×time interactions for the anger, anxiety, and sadness versus neutral condition on endothelial cell-derived microparticles and endothelial progenitor cells from baseline to 40 minutes. In this randomized controlled experimental study, a brief provocation of anger adversely affected endothelial cell health by impairing endothelium-dependent vasodilation.

Autologous bone marrow-derived mesenchymal stem cells and endothelial progenitor cells transplantation showed potential benefits for type 2 diabetes mellitus Filipino patients: a case series

Autologous bone marrow-derived mesenchymal stem cells and endothelial progenitor cells transplantation showed potential benefits for type 2 diabetes mellitus Filipino patients: a case series

ITRI Biofilm Prevented Thoracic Adhesion in Pigs That Received Myocardial Ischemic Induction Treated by Myocardial Implantation of EPCs and ECSW Treatment.

This study tested the hypothesis that ITRI Biofilm prevents adhesion of the chest cavity. Combined extracorporeal shock wave (ECSW) + bone marrow-derived autologous endothelial progenitor cell (EPC) therapy was superior to monotherapy for improving heart function (left ventricular ejection fraction [LVEF]) in minipigs with ischemic cardiomyopathy (IC) induced by an ameroid constrictor applied to the mid-left anterior descending artery. The minipigs (n = 30) were equally designed into group 1 (sham-operated control), group 2 (IC), group 3 (IC + EPCs/by directly implanted into the left ventricular [LV] myocardium; 3 [+]/3[-] ITRI Biofilm), group 4 (IC + ECSW; 3 [+]/[3] - ITRI Biofilm), and group 5 (IC + EPCs-ECSW; 3 [+]/[3] - ITRI Biofilm). EPC/ECSW therapy was administered by day 90, and the animals were euthanized, followed by heart harvesting by day 180. In vitro studies demonstrated that cell viability/angiogenesis/cell migratory abilities/mitochondrial concentrations were upregulated in EPCs treated with ECSW compared with those in EPCs only (all Ps < 0.001). The LVEF was highest in group 1/lowest in group 2/significantly higher in group 5 than in groups 3/4 (all Ps < 0.0001) by day 180, but there was no difference in groups 3/4. The adhesion score was remarkably lower in patients who received ITRI Biofilm treatment than in those who did not (all Ps <0.01). The protein expressions of oxidative stress (NOX-1/NOX-2/oxidized protein)/apoptotic (mitochondrial-Bax/caspase3/PARP)/fibrotic (TGF-β/Smad3)/DNA/mitochondria-damaged (γ-H2AX/cytosolic-cytochrome-C/p-DRP1), and heart failure/pressure-overload (BNP [brain natriuretic peptide]/β-MHC [beta myosin heavy chain]) biomarkers displayed a contradictory manner of LVEF among the groups (all Ps < 0.0001). The protein expression of endothelial biomarkers (CD31/vWF)/small-vessel density revealed a similar LVEF within the groups (all Ps < 0.0001). ITRI Biofilm treatment prevented chest cavity adhesion and was superior in restoring IC-related LV dysfunction when combined with EPC/ECSW therapy compared with EPC/ECSW therapy alone.

Enhancement of de novo lipogenesis by the IDH1 and IDH2-dependent reverse TCA cycle maintains the growth and angiogenic capacity of bone marrow-derived endothelial progenitor cells under hypoxia

BackgroundBone marrow-derived endothelial progenitor cells (EPCs) play a dynamic role in maintaining the structure and function of blood vessels. But how these cells maintain their growth and angiogenic capacity under bone marrow hypoxic niche is still unclear. This study aims to explore the mechanisms from a perspective of cellular metabolism. MethodsXFe96 Extracellular Flux Analyzer was used to analyze the metabolic status of EPCs. Gas Chromatography-Mass Spectrometry (GC-MS) was used to trace the carbon movement of 13C-labeled glucose and glutamine under 1 % O2 (hypoxia) and ∼20 % O2 (normoxia). Moreover, RNA interference, targeting isocitrate dehydrogenase-1 (IDH1) and IDH2, was used to inhibit the reverse tricarboxylic acid (TCA) cycle and analyze metabolic changes via isotope tracing as well as changes in cell growth and angiogenic potential under hypoxia. The therapeutic potential of EPCs under hypoxia was investigated in the ischemic hindlimb model. ResultsCompared with normoxic cells, hypoxic cells showed increased glycolysis and decreased mitochondrial respiration. Isotope metabolic tracing revealed that under hypoxia, the forward TCA cycle was decreased and the reverse TCA cycle was enhanced, mediating the conversion of α-ketoglutarate (α-KG) into isocitrate/citrate, and de novo lipid synthesis was promoted. Downregulation of IDH1 or IDH2 under hypoxia suppressed the reverse TCA cycle, attenuated de novo lipid synthesis (DNL), elevated α-KG levels, and decreased the expression of hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor A (VEGFA), eventually inhibiting the growth and angiogenic capacity of EPCs. Importantly, the transplantation of hypoxia-cultured EPCs in a mouse model of limb ischemia promoted new blood vessel regeneration and blood supply recovery in the ischemic area better than the transplantation of normoxia-cultured EPCs. ConclusionsUnder hypoxia, the IDH1- and IDH2-mediated reverse TCA cycle promotes glutamine-derived de novo lipogenesis and stabilizes the expression of α-KG and HIF-1α, thereby enhancing the growth and angiogenic capacity of EPCs.

Matrix stiffness regulates neovascular homeostasis through autophagy in nude mice.

One of the major obstacles to the effective application of vascularized fruit is an insufficient understanding of the relationship between the microenvironment and neovascular homeostasis. The role of extracellular matrixstiffness in regulating the structural and functional stability of neovascularization has not yet been elucidated. This study explored the effects of matrix stiffness on neovascular homeostasis in nude mice. Dextran hydrogels with three different stiffnesses were separately combined with mouse bone marrow-derived endothelial progenitor cells (EPCs) and subcutaneously implanted into the backs of nude mice. After 14 days, neovascular homeostasis indicators in the different groups were measured. Cell autophagy levels were evaluated, and inhibitor assays were performed to explore the underlying mechanism. New blood vessels were generated in the three stiffnesses of the EPC-loaded dextran hydrogels 14 days after implantation. The newly formed vessels tended to have better structural stability in softer hydrogels. Endothelial function markers, such as endothelial nitric oxide synthaseand E-selectin, were downregulated as the matrix stiffness increased. Furthermore, we found that cell autophagy levels decreased in stiffer matrices, and autophagy inhibition attenuated neovascular homeostasis. A soft matrix is conducive to maintaining neovascular homeostasis through autophagy in nude mice.

Promotion of NAD+ recycling by the hypoxia-induced shift in the lactate dehydrogenase isozyme profile reduces the senescence of human bone marrow-derived endothelial progenitor cells

Expansion of bone marrow-derived endothelial progenitor cells (EPCs) in vitro to obtain required cell numbers for therapeutic applications faces the challenge of growing cell senescence under the traditional normoxic culture condition. We previously found that 1% O2 hypoxic culture condition is favorable for reducing senescence of EPCs, but the mechanisms underlying the favorability are still unclear. Here, we found that, compared with normoxia, hypoxia induced a shift in lactate dehydrogenase (LDH) isozyme profile, which manifested as decreased LDH2 and LDH1 and increased LDH5, LDH4 and total LDHs. Moreover, under hypoxia, EPCs presented higher LDH activity, which could promote the conversion of pyruvate to lactate, as well as a higher level of NAD+, Bcl2 interacting protein 3 (BNIP3) expression and mitophagy. Additionally, under hypoxia, knock-down of the LDHA subunit increased the LDH2 and LDH1 levels and knock-down of the LDHB subunit increased the LDH5 level, while the simultaneous knock-down of LDHA and LDHB reduced total LDHs and NAD+ level. Inhibition of NAD+ recycling reduced BNIP3 expression and mitophagy and promoted cell senescence. Taken together, these data demonstrated that 1% O2 hypoxia induces a shift in the LDH isozyme profile, promotes NAD+ recycling, increases BNIP3 expression and mitophagy, and reduces EPC senescence. Our findings contribute to a better understanding of the connection between hypoxic culture conditions and the senescence of bone marrow-derived EPCs and provide a novel strategy to improve in vitro expansion of EPCs.

Hypoxia-induced reprogramming of glucose-dependent metabolic pathways maintains the stemness of human bone marrow-derived endothelial progenitor cells

The benefits of hypoxia for maintaining the stemness of cultured human bone marrow-derived endothelial progenitor cells (BM EPCs) have previously been demonstrated but the mechanisms responsible remain unclear. Growing evidences suggest that cellular metabolism plays an important role in regulating stem cell fate and self-renewal. Here we aimed to detect the changes of glucose metabolism and to explore its role on maintaining the stemness of BM EPCs under hypoxia. We identified the metabolic status of BM EPCs by using extracellular flux analysis, LC–MS/MS, and 13C tracing HPLC-QE-MS, and found that hypoxia induced glucose metabolic reprogramming, which manifested as increased glycolysis and pentose phosphate pathway (PPP), decreased tricarboxylic acid (TCA) and mitochondrial respiration. We further pharmacologically altered the metabolic status of cells by employing various of inhibitors of key enzymes of glycolysis, PPP, TCA cycle and mitochondria electron transport chain (ETC). We found that inhibiting glycolysis or PPP impaired cell proliferation either under normoxia or hypoxia. On the contrary, inhibiting pyruvate oxidation, TCA or ETC promoted cell proliferation under normoxia mimicking hypoxic conditions. Moreover, promoting pyruvate oxidation reverses the maintenance effect of hypoxia on cell stemness. Taken together, our data suggest that hypoxia induced glucose metabolic reprogramming maintains the stemness of BM EPCs, and artificial manipulation of cell metabolism can be an effective way for regulating the stemness of BM EPCs, thereby improving the efficiency of cell expansion in vitro.

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

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

Melatonin Inhibits VEGF-Induced Endothelial Progenitor Cell Angiogenesis in Neovascular Age-Related Macular Degeneration.

Neovascular age-related macular degeneration (AMD) is described as abnormal angiogenesis in the retina and the leaking of fluid and blood that generates a huge, dark, blind spot in the center of the visual field, causing severe vision loss in over 90% of patients. Bone marrow-derived endothelial progenitor cells (EPCs) contribute to pathologic angiogenesis. Gene expression profiles downloaded from the eyeIntegration v1.0 database for healthy retinas and retinas from patients with neovascular AMD identified significantly higher levels of EPC-specific markers (CD34, CD133) and blood vessel markers (CD31, VEGF) in the neovascular AMD retinas compared with healthy retinas. Melatonin is a hormone that is mainly secreted by the pineal gland, and is also produced in the retina. Whether melatonin affects vascular endothelial growth factor (VEGF)-induced EPC angiogenesis in neovascular AMD is unknown. Our study revealed that melatonin inhibits VEGF-induced stimulation of EPC migration and tube formation. By directly binding with the VEGFR2 extracellular domain, melatonin significantly and dose-dependently inhibited VEGF-induced PDGF-BB expression and angiogenesis in EPCs via c-Src and FAK, NF-κB and AP-1 signaling. The corneal alkali burn model demonstrated that melatonin markedly inhibited EPC angiogenesis and neovascular AMD. Melatonin appears promising for reducing EPC angiogenesis in neovascular AMD.

S-38-3: LONG NONCODING RNA P21 ALLEVIATES ENDOTHELIAL PROGENITOR CELLS DAMAGE AND PROMOTES ENDOTHELIAL REPAIR IN HYPERTENSION THROUGH ENHANCING AUTOPHAGY

Objective: Vascular damage of hypertension has been the focus of hypertension treatment, and endothelial progenitor cells (EPCs) play an important role in the repair of vascular endothelial damage. Functional damage and decreased number of EPCs are observed in the peripheral circulation of hypertensive patients, but its mechanism is not yet elucidated. Methods: Peripheral circulating endothelial progenitor cells of hypertensive patients were labeled and detected by flow cytometry. At the same time, the endothelial progenitor cells of hypertensive patients were cultured in vitro to detect their cell function and aging. The rat bone marrow-derived endothelial progenitor cells were isolated and cultured in vitro. After the intervention of AngII, the cell function, autophagy, and cell senescence were detected. PCR and WB were used to measure the expression and phosphorylation of SESN2, AMPK and TSC2. Results: Our results showed that the number of EPCs in hypertensive patients is significantly lower than that of normal population, and the cell function decreases with a higher proportion of EPCs at later stages. A decrease in autophagy is responsible for the senescence and damage of EPCs induced by AngII. Moreover, lncRNA-p21 plays a critical regulator role in the senescence and dysfunction of EPCs. Furthermore, lncRNA-p21 activates SESN2/AMPK/TSC2 pathway by promoting the transcriptional activity of p53 and lncRNA-p21 overexpression enhanced autophagy via AMPK/TSC2/mTOR pathway to protect against AngII-induced EPC damage. EPCs with lncRNA-p21 knockdown showed poor adhesion ability and vascular repair function. These results suggest that lncRNA-p21 enhances autophagy to alleviate endothelial progenitor cells damage and promote endothelial repair in hypertension through SESN2/AMPK/TSC2 pathway. Conclusion: The data provide evidence that a reversal of decreased autophagy serves as the protective mechanism of EPC injury in hypertensive patients, and lncRNA-p21 is a new therapeutic target for vascular endothelial repair in hypertension.

Infusion of Cultured Endothelial Progenitor Cells Boosts Hematopoietic Recovery and Increases the Expression of LepR+ Cells after Irradiation

The hemopoietic system's function of producing blood cells and immune cells during thorough life relies on the Maintainance and differentiation of hematopoietic stem cells (HSCs). HSCs activities were tightly and finely tuned by a specialized microenvironment called "niche" in the bone marrow. However, during the routine treatment of hematopoietic diseases, such as chemotherapy and radiotherapy, the niche was inevitably impaired which is one of the essential causes of hematopoietic suppression. Our previous research results showed that infusion of cultured endothelial progenitor cells (EPCs) could boost hematopoietic recovery after HSCT. And the latent mechanisms could be that EPCs can differentiate into endothelial cells (ECs) in vivo. However, the roles of EPCs play in the bone marrow niche and the specific mechanism remain unknown. Here we designed further to investigate the effect and mechanism of EPCs in boosting bone marrow microenvironment recovery after total body irradiation (TBI). This may offer a new cue for therapy of hematopoietic suppression after the treatment of malignant hematological diseases. Bone marrow-derived Primary EPCs isolation and culture were described as before. Briefly, Bone marrow cells from Balb/c or C57BL/6J mice aged 6-8 weeks were cultured with EGM-2 medium which was changed in 36 h, the adherent cells formed colonies identified as elongated sprouting cells radiating from a central core of round cells and identified as VEGFR2+; CD133+; CD144+; SCA1+ by FACS on days 4-6. To assess the effects of the EPCs in boosting hematopoiesis, Balb/c mice underwent TBI with a lethal dose and were injected withEPCs or the same volume of PBS via tail vein in 4-6 hours. The survival of the EPC group was elevated ( survival: 8/9 vs 0/13; p＜0.001). C57BL/6J mice underwent TBI with a sublethal dose and were injected with the cultured EPCs isolated from C57BL/6-Tg(CAG-EGFP) mice or the same volume of PBS via tail vein in 4-6 hours. Results showed that EPCs boost the recovery of hematopoietic cells in the bone marrow and peripheral blood cells; Immunofluence (IF) staining showed that Infused EPCs with GFP fluorescence were home to bone marrow and differentiated into ECs which were marked with endomucin (EMCN); Moreover, assessments of the alteration of bone marrow niche using H&E staining revealed that infusion of EPCs reduced the accumulation of fat and using multi-analyte flow assay showed that mice infused with EPCs express a higher level of M-CSF and TGF-β in plasma while the level of SCF and IL-6 both in plasma and bone marrow supernatant were lower compared to TBI. Furthermore, to assess the change of sinusoidal niche, we used IF staining and found that the sinusoids were dilated and perisinusoidal stromal cells identified as LepR+ were massively lost on the 7th day after TBI while the dilated sinusoidal lumens were narrowed (11.05±1.789 vs 20.86±4.573，p=0.0258) and LepR+ cells were upregulated on the 21st day after the infusion of EPCs which indicated that the sinusoidal niche has a better recovery compared to TBI. In Conclusion, EPCs could differentiate into endothelial cells in vivo boosting the recovery of the hematopoietic system. And the potential mechanism is that EPCs repair the bone marrow sinusoidal niche damaged by irradiation.

Low-dose nifedipine rescues impaired endothelial progenitor cell-mediated angiogenesis in diabetic mice.

It is of great clinical significance to develop potential novel strategies to prevent diabetic cardiovascular complications. Endothelial progenitor cell (EPC) dysfunction is a key contributor to diabetic vascular complications. In the present study we evaluated whether low-dose nifedipine could rescue impaired EPC-mediated angiogenesis and prevent cardiovascular complications in diabetic mice. Diabetes was induced in mice by five consecutive injections of streptozotocin (STZ, 60 mg·kg-1·d-1, i.p.). Diabetic mice were treated with low-dose nifedipine (1.5 mg·kg-1·d-1, i.g.) for six weeks. Then, circulating EPCs in the peripheral blood were quantified, and bone marrow-derived EPCs (BM-EPCs) were prepared. We showed that administration of low-dose nifedipine significantly increased circulating EPCs, improved BM-EPCs function, promoted angiogenesis, and reduced the cerebral ischemic injury in diabetic mice. Furthermore, we found that low-dose nifedipine significantly increased endothelial nitric oxide synthase (eNOS) expression and intracellular NO levels, and decreased the levels of intracellular O2.- and thrombospondin-1/2 (TSP-1/2, a potent angiogenesis inhibitor) in BM-EPCs of diabetic mice. In cultured BM-EPCs, co-treatment with nifedipine (0.1, 1 μM) dose-dependently protected against high-glucose-induced impairment of migration, and suppressed high-glucose-induced TSP-1 secretion and superoxide overproduction. In mice with middle cerebral artery occlusion, intravenous injection of diabetic BM-EPCs treated with nifedipine displayed a greater ability to promote local angiogenesis and reduce cerebral ischemic injury compared to injection of diabetic BM-EPCs treated with vehicle, and the donor-derived BM-EPCs homed to the recipient ischemic brain. In conclusion, low-dose nifedipine can enhance EPCs' angiogenic potential and protect against cerebral ischemic injury in diabetic mice. It is implied that chronic treatment with low-dose nifedipine may be a safe and economic manner to prevent ischemic diseases (including stroke) in diabetes.

Apolipoprotein A1 Enhances Endothelial Cell Survival in an In Vitro Model of ALS.

Altered lipoprotein metabolism is considered a pathogenic component of amyotrophic lateral sclerosis (ALS). Apolipoprotein A1 (ApoA1), a major high-density lipoprotein (HDL) protein, is associated with prevention of vascular damage. However, ApoA1’s effects on damaged endothelium in ALS are unknown. This study aimed to determine therapeutic potential of ApoA1 for endothelial cell (EC) repair under a pathologic condition reminiscent of ALS. We performed in vitro studies using mouse brain ECs (mBECs) exposed to plasma from symptomatic G93A SOD1 mice. Dosage effects of ApoA1, including inhibition of the phosphoinoside 3-kinase (PI3K)/Akt signaling pathway and integration of ApoA1 into mBECs were examined. Also, human bone marrow-derived endothelial progenitor cells (hBM-EPCs) and mBECs were co-cultured without cell contact to establish therapeutic mechanism of hBM-EPC transplantation. Results showed that ApoA1 significantly reduced mBEC death via the PI3K/Akt downstream signaling pathway. Also, ApoA1 was incorporated into mBECs as confirmed by blocked ApoA1 cellular integration. Co-culture system provided evidence that ApoA1 was secreted by hBM-EPCs and incorporated into injured mBECs. Thus, our study findings provide important evidence for ApoA1 as a potential novel therapeutic for endothelium protection in ALS. This in vitro study lays the groundwork for further in vivo research to fully determine therapeutic effects of ApoA1 in ALS.

Hydrogen Repairs LPS-Induced Endothelial Progenitor Cells Injury via PI3K/AKT/eNOS Pathway.

Endotoxins and other harmful substances may cause an increase in permeability in endothelial cells (ECs) monolayers, as well as ECs shrinkage and death to induce lung damage. Lipopolysaccharide (LPS) can impair endothelial progenitor cells (EPCs) functions, including proliferation, migration, and tube formation. EPCs can migrate to the damaged area, differentiate into ECs, and participate in vascular repair, which improves pulmonary capillary endothelial dysfunction and maintains the integrity of the endothelial barrier. Hydrogen (H2) contributes to the repairment of lung injury and the damage of ECs. We therefore speculate that H2 protects the EPCs against LPS-induced damage, and it’s mechanism will be explored. The bone marrow-derived EPCs from ICR Mice were treated with LPS to establish a damaged model. Then EPCs were incubated with H2, and treated with PI3K inhibitor LY294002 and endothelial nitric oxide synthase (eNOS) inhibitor L-NAME. MTT assay, transwell assay and tube formation assay were used to detect the proliferation, migration and angiogenesis of EPCs. The expression levels of target proteins were detected by Western blot. Results found that H2 repaired EPCs proliferation, migration and tube formation functions damaged by LPS. LY294002 and L-NAME significantly inhibited the repaired effect of H2 on LPS-induced dysfunctions of EPCs. H2 also restored levels of phosphor-AKT (p-AKT), eNOS and phosphor-eNOS (p-eNOS) suppressed by LPS. LY294002 significantly inhibited the increase of p-AKT and eNOS and p-eNOS expression exposed by H2. L-NAME significantly inhibited the increase of eNOS and p-eNOS expression induced by H2. H2 repairs the dysfunctions of EPCs induced by LPS, which is mediated by PI3K/AKT/eNOS signaling pathway.

CXCL12 regulates bone marrow–derived endothelial progenitor cells to promote aortic aneurysm recovery

Bone marrow-derived endothelial progenitor cells (EPCs) have been proven to participate in the recovery of aortic aneurysm. CXCL12 promotes EPC recruitment and revascularization. Therefore, this study was dedicated to fathoming out whether EPCs regulated by CXCL12 can participate in the recovery of aneurysm. The morphology and maker protein activity of EPCs derived from bone marrow were separately detected by microscopic examination and immunofluorescence. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blot were performed to detect the transfection efficiency of CXCL12. Lumen formation, viability, and migration were determined by lumen formation, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and wound-healing assays, respectively. The aneurysm tissues in rat model of artery aneurysm were used for histopathological observation by haematoxylin-eosin (HE) staining, α-SMA was detected by immunohistochemistry, and the expressions of VEGF, IGF1, FGF, PDGF and matrix metalloproteinase-2/9 (MMP-2/9) were measured by RT-qPCR and western blot assays. As a result, some EPCs showed fusiform on day 6, while others showed a cord-like structure. On day 17, cells presented a paving stone-like pattern. The expressions of CD34, CD133 and VEGFR2 were positive. CXCL12 overexpression promoted lumen formation, viability and migration of EPCs, and further facilitated growth of smooth muscle-like cells in the aneurysm cavity and VEGF expression, while inhibiting MMP-2/9 expression in the aneurysm tissues in vivo. The present study suggested that CXCL12 overexpression strengthened the lumen formation, viability, and migration of EPCs, and CXCL12-primed EPCs had better effects on aneurysm recovery than unmodified EPCs did.

A Novel Approach to Enhance the Regenerative Potential of Circulating Endothelial Progenitor Cells in Patients with End-Stage Kidney Disease.

Circulating bone marrow-derived endothelial progenitor cells (EPCs) facilitate vascular repair in several organs including the kidney but are progressively diminished in end-stage kidney disease (ESKD) patients, which correlates with cardiovascular outcomes and related mortality. We thus determined if enhancing the tissue-reparative effects of human bone marrow-derived mesenchymal stromal cells (BM-MSCs) with the vasculogenic effects of recombinant human relaxin (RLX) could promote EPC proliferation and function. CD34+ EPCs were isolated from the blood of healthy and ESKD patients, cultured until late EPCs had formed, then stimulated with BM-MSC-derived condition media (CM; 25%), RLX (1 or 10 ng/mL), or both treatments combined. Whilst RLX alone stimulated EPC proliferation, capillary tube formation and wound healing in vitro, these measures were more rapidly and markedly enhanced by the combined effects of BM-MSC-derived CM and RLX in EPCs derived from both healthy and ESKD patients. These findings have important clinical implications, having identified a novel combination therapy that can restore and enhance EPC number and function in ESKD patients.

Salvianolic Acid B Suppresses ER Stress-Induced NLRP3 Inflammasome and Pyroptosis via the AMPK/FoxO4 and Syndecan-4/Rac1 Signaling Pathways in Human Endothelial Progenitor Cells.

Mounting evidence demonstrates uncontrolled endoplasmic reticulum (ER) stress responses can activate the inflammasome, which generally results in endothelial dysfunction, a major pathogenetic factor of chronic inflammatory diseases such as atherosclerosis. Salvianolic acid B (SalB), produced by Radix Salviae, exerts antioxidative and anti-inflammatory activities in multiple cell types. However, SalB's effects on ER stress-related inflammasome and endothelial dysfunction remain unknown. Here, we showed SalB substantially abrogated ER stress-induced cell death and reduction in capillary tube formation, with declined intracellular reactive oxygen species (ROS) amounts and restored mitochondrial membrane potential (MMP), as well as increased expression of HO-1 and SOD2 in bone marrow-derived endothelial progenitor cells (BM-EPCs). ER stress suppression by CHOP or caspase-4 siRNA transfection attenuated the protective effect of SalB. Additionally, SalB alleviated ER stress-mediated pyroptotic cell death via the suppression of TXNIP/NLRP3 inflammasome, as evidenced by reduced cleavage of caspase-1 and interleukin- (IL-) 1β and IL-18 secretion levels. Furthermore, this study provided a mechanistic basis that AMPK/FoxO4/KLF2 and Syndecan-4/Rac1/ATF2 signaling pathway modulation by SalB substantially prevented BM-EPCs damage associated with ER stress by decreasing intracellular ROS amounts and inducing NLRP3-dependent pyroptosis. In summary, our findings identify that ER stress triggered mitochondrial ROS release and NLRP3 generation in BM-EPCs, while SalB inhibits NLRP3 inflammasome-mediated pyroptotic cell death by regulating the AMPK/FoxO4/KLF2 and Syndecan-4/Rac1/ATF2 pathways. The current findings reveal SalB as a potential new candidate for the treatment of atherosclerotic heart disease.

AGEs/RAGE Promote Osteogenic Differentiation in Rat Bone Marrow-Derived Endothelial Progenitor Cells via MAPK Signaling.

Systemic vascular impairment is the most common complication of diabetes. Advanced glycation end products (AGEs) can exacerbate diabetes-related vascular damage by affecting the intima and media through a variety of mechanisms. In the study, we demonstrated that AGEs and their membrane receptor RAGE could induce the differentiation of EPCs into osteoblasts under certain circumstances, thereby promoting accelerated atherosclerosis. Differentiation into osteoblasts was confirmed by positive staining for DiI-acetylated fluorescently labeled low-density lipoprotein and FITC-conjugated Ulex europaeus agglutinin. During differentiation, expression of receptor for AGE (RAGE) was significantly upregulated. This upregulation was attenuated by transfection with RAGE-targeting small interfering (si)RNA. siRNA-mediated knockdown of RAGE expression significantly inhibited the upregulation of AGE-induced calcification-related proteins, such as runt-related transcription factor 2 (RUNX2) and osteoprotegerin (OPG). Additional experiments showed that AGE induction of EPCs significantly induced ERK, p38MAPK, and JNK activation. The AGE-induced upregulation of osteoblast proteins (RUNX2 and OPG) was suppressed by treatment with a p38MAPK inhibitor (SB203580) or JNK inhibitor (SP600125), but not by treatment with an ERK inhibitor (PD98059), which indicated that AGE-induced osteoblast differentiation from EPCs may be mediated by p38MAPK and JNK signaling, but not by ERK signaling. These data suggested that AGEs may bind to RAGE on the EPC membrane to trigger differentiation into osteoblasts. The underlying mechanism appears to involve the p38MAPK and JNK1/2 pathways, but not the ERK1/2 pathway.

Compound Tongluo Decoction promotes generation and homing of endothelial progenitor cells after cerebral infarction in rats by activating Shh signaling

&#x0D; &#x0D; &#x0D; &#x0D; Purpose: To investigate the protective effects of Compound Tongluo decoction (CTD)on neurological function in rats, and the mechanism involved in its angiogenesis-promoting effect.&#x0D; Methods: Rats were arbitrarily assigned to sham group, permanent middle cerebral artery infarction (pMCAO) group, and PMCAO+CTD group (pMCAO plus 7-day oral treatment with CTD). Neurological deficit scores and volume of stroke-damaged areas were measured after 7 days of treatment. The levels of bone marrow-derived endothelial progenitor cells (BMEPCs) in serum and brain tissues were determined by flow cytometry and immunofluorescence. The expression levels of sonic hedgehog (Shh), vascular endothelial growth factor (VEGF), and angiopoietin-1(Ang-1) at infarct sites and in BMEPCs were quantitated using western blot assay.&#x0D; Results: The results showed that CTD markedly ameliorated neurological deficit, reduced volume of affected areas, and promoted the production and homing of BMEPCs. Moreover, CTD upregulated Shh, VEGF and Ang-1expressions at ischemic sites and EPCs, but promoted the proliferation and metastasis of EPCs. The CTD-induced changes were significantly suppressed by Shh inhibitor cyclopamine (CP).&#x0D; Conclusion: These results demonstrate that CTD promotes angiogenesis after cerebral infarction, probably by stimulating Shh signaling and triggering production and homing of EPCs, thereby providing neuroprotection against cerebral infarction. Thus, CTD is a potential neuroprotective agent against cerebral infarction in humans.&#x0D; &#x0D; &#x0D; &#x0D;

CXCR4 protects bone marrow-derived endothelial progenitor cells against hypoxia through the PI3K/Akt signaling pathway.

The present study aimed to investigate the regulatory mechanism of chemokine (C-X-C motif) receptor 4 (CXCR4) on endothelial progenitor cells (EPCs) through the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathway under hypoxic conditions. Mononuclear cells were isolated from the bone marrow (BM) of young Sprague-Dawley (SD) rats. Bone marrow-derived endothelial progenitor cells (BM-EPCs) were characterized by using Dil-labeled acetylated low-density lipoprotein (Dil-ac-LDL) and fluorescein isothiocyanate-labeled UEA (FITC-UEA-1). Phenotype identification of BM-EPCs was based on red cytoplasm and green cytomembrane. Flow cytometry was employed to examine the markers CD14, CD34, and KDR. Expression level of the EPC-specific surface marker CD14 was found to be negative, while the expression level of CD34 and KDR was positive. In addition, CXCR4 was stably overexpressed in BM-EPCs after transfection with adenovirus-CXCR4. Cell proliferation, migration and apoptosis abilities were measured through the application of CCK-8, followed by Transwell and flow cytometry assays. The expression level of CXCR4, PI3K and Akt was determined by reverse transcription-quantitative PCR and western blotting assays. Functional experiments demonstrated that hypoxia inhibited BM-EPC proliferation and migration, while accelerating BM-EPC apoptosis. Additionally, CXCR4 was found to promote proliferation and migration, and suppress apoptosis in BM-EPCs with or without hypoxia treatment. Evidence also demonstrated that CXCR4 markedly upregulated the expression levels of PI3K and Akt. Furthermore, PI3K inhibitor (LY294002) and CXCR4 inhibitor (AMD3100) effectively inhibited the proliferation, migration and resistance to apoptosis of CXCR4-mediated BM-EPCs under hypoxic conditions.