Israel Medical Association Journal

Background: Heart failure with preserved ejection fraction (HFpEF) is a common clinical entity, with a mechanism that appears to involve endothelial dysfunction of the cardiac microcirculation. Endothelial progenitor cells (EPC) are bone marrow derived cells that are able to differentiate into functional endothelial cells and participate in endothelial surface repair.

Objectives: To compare the level and function of EPCs in patients with HFpEF compared with heart failure with reduced ejection fraction (HFrEF) and control subjects.

Methods: We enrolled 21 patients with HFpEF (LVEF ≥ 50%, age 74.5 ± 9.9 years, 43% men, 48% diabetes), 20 patients with HFrEF (LVEF < 40%, age 70 ± 11.5 years, 90% men, 60% diabetes), and 11 control subjects with cardiovascular risk factors (age 53.3 ± 6.1years, 90% men, 64% diabetes). Circulating EPC levels were evaluated by expression of vascular endothelial growth factor receptor-2 (VEGFR-2), CD34, and CD133 by flow-cytometry. EPCs colony forming units (CFUs) were quantified after 7 days in culture.

Results: The proportion of cells that co-expressed VEGFR-2 and CD34 or VEGFR-2 and CD133 was similar among the HFpEF and HFrEF groups, and significantly lower than in the control group. The number of EPC-CFUs was also similar among the two heart failure groups and significantly lower than the control group.

Conclusions: Patients with HFpEF, like HFrEF, have significant reduction in EPC level and function.

Background: Endothelial progenitor cells may have a role in ongoing endothelial repair. Impaired mobilization or depletion of these cells may contribute to progression of vascular disease. Our hypothesis was that endothelial progenitor cells would be suppressed in patients with acute cerebrovascular event based on our previous study that found severe endothelial dysfunction in those patients.

Objectives: To study the ability of patients with acute stroke to build colonies of endothelial progenitor cells.

Methods: We studied the number of colony-forming units of endothelial progenitor cells (CFU-EPCs) from the peripheral blood of 22 male patients with a first-time acute stroke (age 58.09 ± 9.8 years) and 13 healthy men (34 ± 6.7 years), 8 female patients with a first-time acute stroke (54.6 ± 10.3 years) and 6 healthy women (38.3 ± 11.6 years). Endothelium-dependent function was assessed by high-resolution ultrasonography of the brachial artery that measured the change in diameter of the artery by flow-mediated diameter percent change (FMD%). All patients had strokes demonstrated by a brain computed tomography (CT) scan done on admission. Peripheral blood was drawn soon after admission and was processed for endothelial progenitor cells in culture.

Results: Thirty patients without known cardiovascular risk factors and who did not take any medications were admitted with a first-time acute stroke. All demonstrated a strong correlation between CFU-EPCs grown in culture and endothelial dysfunction (r = 0.827, P < 0.01). Endothelial dysfunction with an FMD% of -2.2 ± 9.7% was noted in male patients vs. 17.5 ± 6.8% in healthy males (P = 0.0001), and -7.2 ± 10.1% in female patients vs. 25.1 ± 7.1% in healthy females (P = 0.0001). CFU-EPCs were 5.5 ± 6.3 in men with stroke vs. 23.75 ± 5.3 in healthy males (P = 0.0001), and 7.6 ± 4.9 in women with stroke vs. 22.25 ± 6.7 in healthy females (P = 0.0004).

Conclusions: Patients with acute stroke had an impaired ability to grow CFU-EPCs in culture and exhibited endothelial dysfunction. The novelty of this study was the discovery of the phenomenon of depressed numbers of EPCs and the poor ability to grow colonies of EPCs in the first 24 hours of the cerebrovascular event.

Background: Circulating endothelial progenitor cells have an important role in the process of vascular repair. Impaired recruitment and function of endothelial progenitor cells is related to the pathophysiology of congestive heart failure. Endothelial progenitor cells have been shown to express the mineralocorticoid receptor. 

Objectives: To investigate the effect of mineralocorticoid receptor antagonists on endothelial progenitor cells in patients with heart failure. 

Methods: Twenty-four patients with compensated heart failure, who were not under mineralocorticoid receptor antagonist therapy, were recruited. Either eplerenone (n=8) or spironolactone (n=16) therapy was initiated. Circulating endothelial progenitor cell level, identified as the proportion of mononuclear cells expressing vascular endothelial growth factor receptor 2 (VEGFR-2), CD133, and CD34, was evaluated by flow cytometry at baseline and after 8 weeks. Following 7 days of culture, colonies were counted by microscopy and MTT assay was performed on randomly selected patients (n=12) to estimate viability.

Results: Both median CD34+/VEGFR2+ and median CD133+/VEGFR2+ increased significantly (P = 0.04 and 0.02, respectively). However, the number of colonies and viability of the cells after therapy (as assessed by the MTT assay) was not significantly different compared with the baseline. 

Conclusions: These preliminary results suggest that mineralocorticoid receptor blockade may enhance endothelial progenitor cells recruitment in patients with compensated heart failure.

Background: Non-mobilized peripheral blood contains mostly committed cells with limited numbers of early progenitors. Objectives: To enrich functional progenitor cells from healthy donors and ischemic heart disease patients by short-term culture of mononuclear cells with defined culture conditions.

Methods: Mononuclear cells obtained from healthy donors and ischemic heart disease patients were cultured for 7 days in a cytokine cocktail. We tested the multilineage differentiation capacities and phenotype of cultured cells.

Results: The short-term culture (7 days) of all study groups with a defined cytokine cocktail resulted in two distinct cell populations (adherent and non-adherent) that differed in their differentiation capacities as well as their cell surface markers. Cultured adherent cells showed higher differentiation potential and expressed endothelial and mesenchymal fibroblast-like surface markers as compared to fresh non-cultured mononuclear cells. The non-adherent cell fraction demonstrated high numbers of colony-forming units, indicating a higher differentiation potential of hematopoietic lineage.

Conclusions: This study proved the feasibility of increasing limited numbers of multipotent progenitor cells obtained from the non-mobilized peripheral blood of healthy donors and ischemic patients. Moreover, we found that each of the two enriched subpopulations (adherent and non-adherent) has a different differentiation potential (mesenchymal, endothelial and hematopoietic).

Background: Experimental and clinical protocols are being developed for the cryopreservation of human hematopoietic progenitor cells. However, the effect of these procedures on the potential for HPC[1] to repopulate bone marrow is unknown.

Objectives: To examine the effect of cryopreservation on the ability of fetal human liver HPC, which include CD34+ cells and long-term culture-initiating cells, to repopulate immunodeficient non-obese diabetic/severe combined immunodeficiency mouse bone marrow.

Methods: Groups of sublethally irradiated NOD[2]/SCID[3] mice were injected intravenously with cryopreserved or freshly isolated fetal human liver HPC.

Results: Seven weeks after transplantation, flow cytometric analysis of bone marrow samples showed that mice that received the transplanted cells (either cryopreserved or freshly isolated) demonstrated both lymphoid and myeloid differentiation as well as the retention of a significant fraction of CD34+ cells. Conclusions: Cryopreserved fetal human liver-derived HPC appear to be capable of initiating human cell engraftment in NOD/SCID mouse bone marrow and open the possibility of using cryopreserved fetal human liver HPC for gene manipulation, gene transfusion therapy, and transplantation purposes.

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[1] HPC = hematopoietic progenitor cells

[2] NOD = non-obese diabetic

[3] SCID = severe combined immunodeficiency