Regulation Of Endothelial Progenitor Cells Research Articles

Research Progress in Prevention and Treatment of Atherosclerosis by Regulating Endothelial Cells with Traditional Chinese Medicine

Atherosclerosis (AS)is an important pathological basis of cardiovascular and cerebrovascular diseases. Its pathogenesis is complex and involves many factors. Traditional Chinese medicine (TCM) has the advantage of multi-link and multi-target intervention in the prevention and treatment of AS, in which the regulation of endothelial progenitor cells (EPCs) is an important research direction. This article will review the research progress of TCM in preventing and treating AS by regulating EPCs.

MicroRNA-126 Regulates Thrombosis Through Endothelial Progenitor Cells.

Thrombosis is a common problem with potentially severe consequences. Endothelial progenitor cells (EPCs) show great potential as a thrombosis therapy due to their angiogenesis-promoting, thrombus-relieving, and anticoagulant functions. However, cell therapies present more clinical challenges than small molecule solutions. MicroRNAs (miRNAs) are small noncoding single-stranded RNAs with wide-ranging regulatory activities. miRNA-126 is highly enriched in EPCs and endothelial cells. Although increasing research showed that mircoRNA-126 (miR-126) can regulate EPC functions through various pathways and cytokines, summaries of these interactions are rare. Therefore, this brief review of recent findings on the relationship between miRNA-126 and EPC function will attempt to clarify the role of miR-126 in thrombosis through regulation of EPCs, with the goal of exploring alternative therapies for thrombotic diseases.

Effects of dulaglutide on endothelial progenitor cells and arterial elasticity in patients with type 2 diabetes mellitus

BackgroundRandomised controlled trial showed that dulaglutide can reduce the risk of atherosclerotic cardiovascular disease (ASCVD) in patients with type 2 diabetes mellitus (T2DM), but the underlying mechanisms remain unclear. This study aimed to investigate the effect of dulaglutide on the number and function of endothelial progenitor cells (EPCs) in the peripheral blood of patients with T2DM and its role in improving arterial elasticity, so as to determine potential mechanisms of preventive effect of dulaglutide on ASCVD.MethodsSixty patients with T2DM were treated with 1000 mg/day of metformin and randomly divided into two groups for 12 weeks: metformin monotherapy group (MET group, n = 30), and metformin combined with dulaglutide group (MET-DUL group, n = 30). Before and after treatment, the number of CD34+CD133+KDR+ EPCs and the brachial–ankle pulse wave velocity (baPWV) of the participants were measured, and EPC proliferation, adhesion, migration, and tubule formation were assessed in vitro.ResultsThere were no significant differences in the number and function of EPCs and baPWV changes in MET group (P > 0.05). In MET-DUL group, nitric oxide (NO) levels and the number of EPCs increased after treatment (P < 0.05), while the levels of C-reactive protein (CRP), interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α), advanced glycation end products (AGEs), and baPWV decreased (P < 0.05). EPC proliferation, adhesion, migration, and tubule formation abilities were significantly enhanced (P < 0.05). Correlation analysis showed that in MET-DUL group, the changes in CRP, IL-6, TNF-α, and AGEs were negatively correlated with the number of EPCs and their proliferation and migration abilities (P < 0.05). Body weight, NO, CRP, and IL-6 levels were independent factors affecting the number of EPCs (P < 0.05). The changes in number of EPCs, proliferation and migration abilities of EPCs, and NO and IL-6 levels were independent influencing factors of baPWV changes (P < 0.05).ConclusionDulaglutide can increase the number and function of EPCs in peripheral blood and improve arterial elasticity in patients with T2DM; it is accompanied by weight loss, inflammation reduction, and high NO levels. Dulaglutide regulation of EPCs may be a mechanism of cardiovascular protection.

Influence of Hypoxia Inducible Factor-1α of Endothelial Progenitor Cells on Left Ventricular Function in Experimental Myocardial Infarction

Based on the promotion of myocardial activity via endothelial progenitor cells (EPCs) subsequent to acute myocardial infarction (AMI), our research was designed to explore the influence of excessive HIF-1α expression in expanded EPCs (eEPCs) on promotion of the activity of left ventricle subsequent to MI. Isolation of EPCs from cord blood was performed before transduction with the help of retroviral vector with or without HIF-1α expression. Transplantation was performed subsequent to ligation of the left anterior descending coronary artery in mice. Ejection fraction (EF) of left ventricle was promoted via transplantation after 2 weeks. Excessive HIF-1α expression enhanced EF of left ventricle and decreased the extent of MI. It was revealed via functional studies that excessive HIF-1α expression enhanced proliferation of EPCs triggered by low oxygen concentration and suppressed cell death in the region of infarction. Moreover, markers of endothelium CD31, VEGF, and eNOS were upregulated. Transplantation of eEPCs with excessive HIF-1α expression in AMI can promote myocardial activities by increasing differentiation, generation of vessels, proliferation of eEPCs, and suppressing cell death. The above findings propose that regulation of EPCs via HIF-1α enhances the activity as well as mobilization of EPCs, indicating that reinforcement of expression of HIF-1α is beneficial for coronary heart disease.

MiR-150 regulates endothelial progenitor cell differentiation via Akt and promotes thrombus resolution

BackgroundDeep venous thrombosis (DVT) constitutes a major global disease burden. Endothelial progenitor cells (EPCs) have been described in association with recanalization of venous thrombus. Furthermore, emerging evidence suggests microRNAs are involved in this progression. The goal of this study was to investigate the influence of miR-150 on the behavior of EPCs and its potential contribution in venous thrombosis resolution.MethodsWe isolated and cultured EPCs from healthy adults. Next, early EPCs or endothelial colony-forming cells (ECFCs or late EPCs) were transfected with miR-150 agomir and antagomir. Gene expression profiles, proliferation, cytokine secretion, and angiogenic capacity of early EPCs and ECFCs were examined. The effects of miR-150 on c-Myb expression and Akt/FOXO1 signaling were also evaluated. Furthermore, a rat model of venous thrombosis was constructed to determine the in vivo function of EPCs.ResultsOur results showed that miR-150 overexpression in early EPCs significantly promoted differentiation to ECFCs and contributed to proliferation and tube formation. However, suppression of miR-150 in late EPCs inhibited proliferation and tube formation. Moreover, we identified that this progression is regulated by inhibition of c-Myb and activation of the Akt/FOXO1 pathway. Our findings also showed that miR-150 led to the enhanced resolution ability of EPCs in a rat venous thrombosis model.ConclusionsIn this study, we present a novel mechanism of miRNA-mediated regulation of EPCs and Akt activation in thrombus resolution.

Downregulation of miR-103a-3p Contributes to Endothelial Progenitor Cell Dysfunction in Deep Vein Thrombosis Through PTEN Targeting

Bone-marrow-derived endothelial progenitor cells (EPCs) can accelerate the dissolution of thrombi. However, EPC functions are weakened in deep vein thrombosis (DVT), and miR-130a-3p is downregulated in DVT. As little is known about the function of miR-130a-3p in EPCs, we aimed to explore the effects of miR-130a-3p on EPC functions and the mechanisms of miR-130a-3p regulation of EPCs in DVT. The EPCs were transfected with miR-130a-3p mimics or miR-130a-3p inhibitor. Migration and angiogenesis of EPCs were detected by wound healing, Transwell, and tube formation assays. Dual luciferase assay was used to test the relation of miR-130a-3p and phosphatase and tensin homolog (PTEN). Protein and mRNA levels of associated genes were measured by western blotting (WB) and qRT-PCR. miR-103a-3p could promote EPC migration and angiogenesis, and it was also downregulated in EPCs isolated from DVT patients. Moreover, PTEN was a target of miR-130a-3p. Upregulation of PTEN rescued the auxoaction of miR-130a-3p in EPC function. Downregulation of miR-103a-3p contributes to EPC dysfunction in DVT via targeting PTEN. Thus, miR-130a-3p may be a potential target for DVT treatment.

Association between Type I interferon and depletion and dysfunction of endothelial progenitor cells in C57BL/6 mice deficient in both apolipoprotein E and Fas ligand

Patients with systemic lupus erythematosus (SLE) have a tremendously increased risk for cardiovascular disease (CVD), which could not be accounted in entirety by traditional Framingham risk factors. To study whether the accelerated atherosclerosis in SLE patients is mediated by type I interferon (IFN-I) through the regulation of endothelial progenitor cells (EPCs), we created a line of C57BL/6 mice with deficiency in both apolipoprotein E (ApoE−/−) and fas ligand (FasL−/−, gld.). As expected, the resultant gld. ApoE−/− mice exhibited both aggravated lupus-like disease and atherosclerosis under normal diet. Increased expression of IFN-I-stimulated genes (ISGs) was closely associated with depletion and dysfunction of EPCs, as well as with accelerated atherosclerotic lesion in gld. ApoE−/− mice. While only IFN-α instead of other interventions, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IRS423 and IRS661, impaired EPC function in vitro. Mechanistically, activation or inhibition of the TLR7/9 signaling could modulate EPC number and function in vivo. Decreased proliferation rate and increased apoptotic rate of EPCs induced by IFN-α might contribute to the results to a certain extent. Thus, our data suggest that excessive expression of IFN-I through the activation of TLR7/9 signaling may induce accelerated atherosclerosis in lupus through the depletion or dysfunction of EPCs, suggesting that targeting IFN-I might have potential therapeutic effects on both lupus disease and premature atherosclerosis in SLE patients.

MiR-503 suppresses hypoxia-induced proliferation, migration and angiogenesis of endothelial progenitor cells by targeting Apelin

Endothelial progenitor cells (EPCs) are of great importance in the process of endogenous blood vessel repair to maintain endothelial integrity and have been applied in a wide range of models of ischemic diseases. MicroRNAs represent a class of non-protein coding endogenous RNAs with 19–24 nucleotides in length and serve an important role in multiple physiological and pathological processes, including angiogenesis. It has been reported that miR-503 reduces angiogenesis in tumorigenesis. However, to our knowledge, the precise role of miR-503 in the regulation of EPCs remains unclear. In the current study, we found that the expression of miR-503 was decreased in mouse bone marrow derived EPCs under the hypoxic condition. Importantly, upregulation of miR-503 suppressed the proliferation, migration and capillary-like tube formation of EPCs induced by hypoxia. Furthermore, a dual luciferase reporter assay showed that Apelin, an endogenous ligand of the G protein-coupled receptor APJ, was a direct target of miR-503 and overexpression of miR-503 significantly inhibited the protein level of Apelin in EPCs. Moreover, hypoxia treatment enhanced the expression of Apelin in EPCs. Meanwhile ectopic expression of Apelin promoted cellular proliferation, migration and tube formation of EPCs in vitro. In summary, our results indicate that miR-503 regulates proliferation, migration and angiogenesis of EPCs by targeting Apelin.

Exercise training with dietary restriction enhances circulating irisin level associated with increasing endothelial progenitor cell number in obese adults: an intervention study.

ObjectiveCirculating endothelial progenitor cells (EPCs) correlate negatively with obesity. Previous studies have shown that exercise significantly restores circulating EPC levels in obese people; however, the underlying mechanisms have not been elucidated. Recently, irisin has been reported to have a critical role in the regulation of EPCs. This exercise-induced myokine has been demonstrated to play a therapeutic role in obesity. In this study, we hypothesized that the increase in circulating irisin may form a link with increasing EPC levels in obese people after exercise.MethodsSeventeen obese adults completed an 8-week program of combined exercise and dietary intervention. Clinical characteristics, blood biochemistry, and circulating irisin levels of subjects were measured before and after eight weeks of training. EPC levels were evaluated via flow cytometry, and EPC migratory and adhesive functions were also determined.ResultsCirculating irisin levels significantly increased following the 8-week training program (P < 0.05). We furthermore observed an improvement in EPC numbers (P < 0.05), and EPC migratory and adhesive functions (P < 0.001 and P < 0.05, respectively) after the intervention. Additionally, we detected a positive correlation between changes in irisin and changes in EPC number (r = 0.52, P < 0.05).DiscussionFor the first time, a positive correlation between increasing irisin levels and increasing EPC levels has been reported after an 8-week program, consisting of exercise and dietary intervention. This result suggests a novel effect of irisin on the regulation of EPC mobilization, which might contribute to improvement of endothelial function in obese people.

Autophagy inhibits endothelial progenitor cells migration via the regulation of MMP2, MMP9 and uPA under normoxia condition

ObjectiveThe aim of this study was to explore the role of autophagy on the regulation of endothelial progenitor cells (EPCs) migration under normoxic condition. MethodsAfter EPCs were isolated and characterized in vitro, we employed Atg5 knocking down and rapamycin to monitor the autophagy, and performed wound healing and transwell assay to assess the cell migration. On the mechanism, the expression of matrix metalloproteinases (MMPs) and urokinase type plasminogen activator (uPA) was evaluated. ResultsAtg5 knocking down and rapamycin could respectively inhibit and enhance autophagy, which could result in significantly increased and decreased cell migration in wound healing and transwell assay under normoxic condition. Moreover, Atg5 knocking down could significantly increase the expression of MMP2, MMP9 and uPA in EPCs while rapamycin could decrease the expression of uPA and MMP9. In addition, the mTOR-P70 S6K pathway was also involved in EPCs migration regulation. ConclusionsThese results demonstrated that autophagy could regulate the EPCs migration through mTOR-P70 S6K pathway, and MMP2, MMP9 and uPA may also involve in the regulation mechanism.

Treatment of antibody-mediated rejection including immunoadsorption during first year after renal transplantation – Clinical results and regulation of endothelial progenitor cells

ObjectiveAntibody-mediated rejection (AMR) is associated with poor allograft survival. Therefore, effective treatment strategies are required. Extracorporeal strategies are increasingly included in treatment of antibody-mediated rejection to eliminate the detrimental alloantibodies. Yet, other mechanisms contributing to the beneficial effect of apheresis besides the removal of antibodies are under consideration. MethodsWe retrospectively analyzed data of 427 transplant patients from 2006 to 2013 with special focus on occurrence, treatment – always including immunoadsorption – and 12-months outcome of antibody-mediated rejection.Besides, we prospectively monitored how the number and phenotype of endothelial progenitor cells in four patients experiencing antibody-mediated rejection changed during the treatment course of 6–20 sessions of immunoadsorption in comparison to seven patients subjected to immunoadsorption because of preparation for ABO-incompatible transplantation. Results24 patients were diagnosed with acute AMR and treated with immunoadsorption resulting in patient and allograft survival of 100% and 87.5%, respectively. In patients with antibody-mediated rejection, the endothelial progenitor cell number after successful immunoadsorption therapy was always transiently decreased and the adhesive and migratory ability improved. This regulation of circulating endothelial precursor cells was not seen in patients undergoing repetitive immunoadsorptions before ABO-incompatible transplantation. ConclusionCombined therapy with immunoadsorption allows a successful treatment of AMR. Treatment seems to be associated with a transient regulation of circulating endothelial precursor cells.

Regulation of EPCs: The Gateway to Blood Vessel Formation

Endothelial progenitor cells (EPCs) are primitive endothelial precursors which are known to functionally contribute to the pathogenesis of disease. To date a number of distinct subtypes of these cells have been described, with differing maturation status, cellular phenotype, and function. Although there is much debate on which subtype constitutes the true EPC population, all subtypes have endothelial characteristics and contribute to neovascularisation. Vasculogenesis, the process by which EPCs contribute to blood vessel formation, can be dysregulated in disease with overabundant vasculogenesis in the context of solid tumours, leading to tumour growth and metastasis, and conversely insufficient vasculogenesis can be present in an ischemic environment. Importantly, it is widely known that transcription factors tightly regulate cellular phenotype and function by controlling the expression of particular target genes and in turn regulating specific signalling pathways. This suggests that transcriptional regulators may be potential therapeutic targets to control EPC function. Herein, we discuss the observed EPC subtypes described in the literature and review recent studies describing the role of a number of transcriptional families in the regulation of EPC phenotype and function in normal and pathological conditions.

Perioperative Implications of Vascular Endothelial Dysfunction: Current Understanding of this Critical Sensor-Effector Organ

The endothelium, a delicate monolayer of cells lining all blood vessels, is a highly responsive sensor-effector organ, which through the secretion of a multitude of mediators, controls vascular tone, interacts with the inflammatory-coagulation cascades, promotes anti-aggregation, regulates immune cellular trafficking, and is crucial to angiogenesis. In brief, the endothelium is a major determinant of vascular homeostasis. It is easily damaged by intrinsic and extrinsic factors, and given its limited capacity for self-repair, is dependent on circulating bone marrow-derived endothelial progenitor cells for regeneration. There is increasing recognition that targeting the endothelium and maximizing inherent physiological function in the perioperative period may improve postoperative outcomes. This review explores the pathogenesis of endothelial dysfunction, the clinical utility of noninvasive methods to assess preoperative endothelial/microvascular (dys)function to improve risk stratification, and potential strategies for perioperative modulation of endothelial function.

Abstract 517: The CYP4A-20-HETE System Regulation of Endothelial Progenitor Cell Functions that Associated with Angiogenesis

The CYP4A-20-HETE system regulates the neovascularization process via its potent vascular effects mainly on endothelial cells and vascular smooth muscle cells. Endothelial progenitor cells (EPC) also actively participate in physiological and pathological neovascularization. Our group first reported that the CYP4A-20-HETE system is present and functional in EPC derived from human umbilical cord blood (HUCB) and that EPC also respond to exogenous 20-HETE with increased proliferation and migration. We hypothesized that the angiogenic actions of the CYP4A-20-HETE system may involve regulation of EPC functions that associated with angiogenesis. In this study, we identified CYP4A11/22 as the main 20-HETE synthases in EPC derived from HUCB by real time PCR. We also examined the effects of exogenous 20-HETE on EPC adhesion since adhesion of EPC to extracellular matrix is an important aspect of EPC homing to the sites where angiogenesis is occurring. We found that 20-HETE (1 μM) increased EPC adhesion to fibronectin and SDF-1α coating by ∼40% and ∼35%, respectively. These increases in adhesion are completely abolished in the presence of 20-hydroxy-6, 15-eicosadienoic acid (20-HEDE), a 20-HETE antagonist. We further established the mouse ischemic hindlimb model to study the effects of pharmacological inhibition of the CYP4A/F-20-HETE system using the 20-HETE synthase inhibitor Dibromo-dodecenyl-methylsulfimide (DDMS) and 20-HEDE on compensatory angiogenesis in response to ischemia. Systemic treatment of animals with 10 mg/kg/day of either DDMS or 20-HEDE inhibited hindlimb compensatory angiogenesis by more than 50% without significant effects on the blood pressure. Specific targeting of the EPC-derived CYP4A-20-HETE system needs to be performed to further dissecting the role of systemic and EPC-derived 20-HETE on angiogenic processes. These findings implicates the CYP4A-20-HETE system as a novel regulator of EPC functions that are associated with angiogenesis and suggests that it can act as both an autocrine and paracrine regulatory factor.

Interleukin-1 Beta Increases Activity of Human Endothelial Progenitor Cells: Involvement of PI3K-Akt Signaling Pathway

Interleukin-1β (IL-1β) is a multifunctional proinflammatory cytokine upregulated in acute phase of heart ischemic disease. Controversial effects of IL-1β have been demonstrated on endothelial progenitor cells (EPCs) functional activity. The aim of this study was to investigate the in vitro effect of IL-1β on activity of human origin EPCs and the possible mechanism involved. EPCs were isolated from peripheral blood of healthy volunteers without cardiovascular risk factors and characterized. After ex vivo cultivation, EPCs were stimulated with a series of final concentrations (0, 0.1, 1, and 10 ng/ml) of IL-1β for 24 h. In some other experiments, EPCs were pretreated with 10 μM LY294002 (Akt inhibitor) for 30 min and then stimulated with 1 ng/ml IL-1β for 24 h. Cell proliferation, apoptosis, adhesion, and migration were determined, respectively, by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, annexin V/propidium iodide binding assay, adhesion assay, and transwell migration assay. In addition, the vascular endothelial vascular growth factor-A (VEGF-A) production has been examined using quantitative real-time RT-PCR and ELISA assay. Furthermore, the total and phosphorylation level of Akt was determined by Western blot. IL-1β significantly stimulated EPC proliferation, migration, and adhesion and upregulated the angiogenic growth factor VEGF-A at mRNA and protein level, while exerted no influence on cell apoptosis. However, pretreatment with LY294002 significantly diminished IL-1β-induced proliferation, migration, adhesion, and VEGF-A production. One nanogram per milliliter IL-1β for 15 min activated phosphorylation of Akt. These results suggest a potent role for IL-1β in upregulating EPCs functions. The phosphatidyl-inositol-3-kinase-Akt signaling pathway could be involved in the regulation of EPCs functions induced by IL-1β.

Effect of recombinant human SDF-1a on re-endothelialization after sirolimus-eluting stent implantation in rabbit aorta abdominalis

AimsAlthough the use of drug-eluting stents (DES) has been shown to limit neointimal hyperplasia in clinical coronary artery disease treatment, currently available DES may adversely affect re-endothelialization (RE) and thus increase fateful stent thrombosis. As stromal cell derived factor 1a (SDF-1a) plays an essential role in the regulation of endothelial progenitor cells (EPCs) mobilization, homing, and differentiation in response to vascular injury, we assumed that SDF-1a may enhance EPCs adhesion and attenuate delayed RE associated with DES. Main methodsBiologically active recombinant human SDF-1a (rhSDF-1a) was first produced using an Escherichia coli expression system. Twenty-four male rabbits were then underwent sirolimus-eluting stents implantation in aorta abdominalis. After operation, they were randomly divided into two groups and subcutaneously injected daily with 50μg/kg rhSDF-1a or the same volume of saline for 7days. Key findingsWith the application of scanning electron microscopy (SEM) and histological analysis, we found that rhSDF-1a significantly promoted RE on days 7, 14, 28 and inhibited neointimal hyperplasia on day 28 after stent implantation. SignificanceOur results revealed a potential role of rhSDF-1a in facilitating RE and inhibiting neointimal proliferation after DES implantation, leading to a conclusion that this protein may be a potential candidate agent for the treatment of in-stent restenosis and stent thrombosis.

Notch-RBP-J Signaling Regulates the Mobilization and Function of Endothelial Progenitor Cells by Dynamic Modulation of CXCR4 Expression in Mice

Bone marrow (BM)-derived endothelial progenitor cells (EPC) have therapeutic potentials in promoting tissue regeneration, but how these cells are modulated in vivo has been elusive. Here, we report that RBP-J, the critical transcription factor mediating Notch signaling, modulates EPC through CXCR4. In a mouse partial hepatectomy (PHx) model, RBP-J deficient EPC showed attenuated capacities of homing and facilitating liver regeneration. In resting mice, the conditional deletion of RBP-J led to a decrease of BM EPC, with a concomitant increase of EPC in the peripheral blood. This was accompanied by a down-regulation of CXCR4 on EPC in BM, although CXCR4 expression on EPC in the circulation was up-regulated in the absence of RBP-J. PHx in RBP-J deficient mice induced stronger EPC mobilization. In vitro, RBP-J deficient EPC showed lowered capacities of adhering, migrating, and forming vessel-like structures in three-dimensional cultures. Over-expression of CXCR4 could at least rescue the defects in vessel formation by the RBP-J deficient EPC. These data suggested that the RBP-J-mediated Notch signaling regulated EPC mobilization and function, at least partially through dynamic modulation of CXCR4 expression. Our findings not only provide new insights into the regulation of EPC, but also have implications for clinical therapies using EPC in diseases.

Potential use of endothelial progenitor cells for regeneration of the vasculature

Over the past decade, interest has been generated in the study of endothelial progenitor cells (EPCs). EPCs have been studied for their role in endogenous maintenance and for their therapeutic potential in vascular regenerative medicine. Despite their obvious potential in clinical practice, there still remain many controversies regarding how EPCs actually enhance endothelial repair and neovascularization. In addition, because of the limited expansion ability of EPCs, expansion of sufficient EPC populations for therapeutic angiogenesis remains a major task. On the other hand, embryonic stem (ES) cells have an extended self-renewal activity and can be expanded without limit, thus ES-cell-derived endothelial cells could be feasible as a novel cell source for therapeutic angiogenesis. In this review, we discuss recent experimental and clinical findings of EPCs and human ES-cell-derived endothelial cells for the treatment of ischemic cardiovascular diseases.

Evidence for genetic regulation of endothelial progenitor cells and their role as biological markers of atherosclerotic susceptibility

Endothelial progenitor cells (EPCs) are found in the peripheral circulation and are capable of endothelial repair and neovascularization. EPC number and function are reduced in subjects with cardiovascular risk factors or proven coronary artery disease (CAD). We hypothesized that EPC number and/or function may be genetically regulated and may vary in healthy adult offspring depending on parental history of CAD. We studied 102 subjects comprising 24 healthy parent-healthy offspring pairs and 27 CAD parent-healthy offspring pairs. We measured the number of circulating CD34(+)VEGFR-2(+) and AC133(+)VEGFR-2(+) EPCs, the number of EPCs grown in culture, and the migration capacity of cultured EPCs towards vascular endothelial growth factor. There was significant correlation in the number of cultured EPCs between healthy parents and their offspring (R = 0.492, P = 0.015) and CAD parents and their offspring (R = 0.751, P < 0.001). Offspring of subjects with CAD had significantly higher numbers of circulating CD34(+)VEGFR-2(+) and AC133(+)VEGFR-2(+) cells (P = 0.018 and P < 0.001, respectively). There was no difference in migration capacity between groups. Our results suggest that EPC number is, at least in part, genetically regulated. Circulating EPCs may represent biological markers of occult vascular damage in offspring with hereditary risk of CAD.

Hypercholesterolemia suppresses Kir channels in porcine bone marrow progenitor cells in vivo

Objective Inwardly-rectifying K + (Kir) channels are responsible for maintaining membrane potentials in a variety of cell types including endothelial cells where they modulate endothelium-dependent vasorelaxation. The goal of this study is to determine the functional expression of Kir channels in porcine bone marrow-derived side population (BM-SP) cells that demonstrate phenotypes of endothelial progenitor cells (EPCs). We further asses the hypercholesterolemia sensitivity of Kir channels in BM-SP cells, which may play a key role in hypercholesterolemia-mediated regulation of EPCs. Methods To assess the effect of hypercholesterolemia on Kir channels in BM-SP, Kir currents were recorded in SP cells sorted from the bone marrow of healthy or hypercholesterolemic animals. Results We found Kir channels constitute the major conductance in porcine bone marrow-derived side population (BM-SP) cells. These cells are defined by their efficiency of Hoechst dye efflux and have been reported to differentiate into multiple cell lineages including endothelium in vivo. We demonstrate here that porcine BM-SP cells differentiate to an endothelial lineage (CD31 +, vWF +) supporting the hypothesis that these cells are endothelial progenitor cells. Also, BM-SP cells express Kir with biophysical properties recapitulating those in mature endothelial cells, but with a much higher current density. Flow cytometric (FACS) analysis indicated that the number of SP cells was unaffected by hypercholesterolemia. However, hypercholesterolemia significantly inhibited Kir channels in BM-SP cells. Conclusions We successfully demonstrate that BM side population cells represent an origin of endothelial progenitor cells. This study further shows, for the fist time, that the functional expression of Kir channels in bone marrow (BM)-derived SP. Moreover, we demonstrate that hypercholesterolemia condition significantly suppresses the Kir channels in BM-SP cells, suggesting that hypercholesterolemia-mediated regulation of Kir channels may be an important factor not only in dysfunction of mature endothelium but also in dysfunction of BM-SP cells.