Relation between the frequency of CD34⁺ bone marrow derived circulating progenitor cells and the number of diseased coronary arteries in patients with myocardial ischemia and diabetes

Behind the monocyte's mystique: uncovering their developmental trajectories and fates

Monocytes are circulating myeloid cells that are derived from dedicated progenitors in the bone marrow. Originally thought of as mere precursors for the replacement of tissue macrophages, it is increasingly clear that monocytes execute distinct effector functions and may give rise to monocyte-derived cells with unique properties from tissue-resident macrophages. Recently, the advent of novel experimental approaches such as single-cell analysis and fate-mapping tools has uncovered an astonishing display of monocyte plasticity and heterogeneity, which we believe has emerged as a key theme in the field of monocyte biology in the last decade. Monocyte heterogeneity is now recognized to develop as early as the progenitor stage through specific imprinting mechanisms, giving rise to specialized effector cells in the tissue. At the same time, monocytes must overcome their susceptibility towards cellular death to persist as monocyte-derived cells in the tissues. Environmental signals that preserve their heterogenic phenotypes and govern their eventual fates remain incompletely understood. In this review, we will summarize recent advances on the developmental trajectory of monocytes and discuss emerging concepts that contributes to the burgeoning field of monocyte plasticity and heterogeneity.

The Long Telling Story of "Endothelial Progenitor Cells": Where Are We at Now?

Endothelial progenitor cells (EPCs): The name embodies years of research and clinical expectations, but where are we now? Do these cells really represent the El Dorado of regenerative medicine? Here, past and recent literature about this eclectic, still unknown and therefore fascinating cell population will be discussed. This review will take the reader through a temporal journey that, from the first discovery, will pass through years of research devoted to attempts at their definition and understanding their biology in health and disease, ending with the most recent evidence about their pathobiological role in cardiovascular disease and their recent applications in regenerative medicine.

Rapid and selective mobilization of specific stem cell types after consumption of a polyphenol-rich extract from sea buckthorn berries (Hippophae) in healthy human subjects

Purpose

The aim of this study was to evaluate the effects of a proanthocyanidin-rich extract of sea buckthorn berry (SBB-PE) on the numbers of various types of adult stem cells in the blood circulation of healthy human subjects.

Study design and methods

A randomized, double-blind, placebo-controlled, cross-over trial was conducted in 12 healthy subjects. Blood samples were taken immediately before and at 1 and 2 hours after consuming either placebo or 500 mg SBB-PE. Whole blood was used for immunophenotyping and flow cytometry to quantify the numbers of CD45dim CD34+ CD309+ and CD45dim CD34+ CD309− stem cells, CD45− CD31+ CD309+ endothelial stem cells, and CD45− CD90+ mesenchymal stem cells.

Results

Consumption of SBB-PE was associated with a rapid and highly selective mobilization of CD45dim CD34+ CD309− progenitor stem cells, CD45− CD31+ CD309+ endothelial stem cells, and CD45− CD90+ lymphocytoid mesenchymal stem cells. In contrast, only minor effects were seen for CD45dim CD34+ CD309+ pluripotential stem cells.

Conclusion

Consumption of SBB-PE resulted in selective mobilization of stem cell types involved in regenerative and reparative functions. These data may contribute to the understanding of the traditional uses of SBB for preventive health, regenerative health, and postponing the aging process.

Collection and immunoselection of CD34+ cells: the impact of age, sex, and diabetes in patients with chronic heart failure

BACKGROUND

Mobilized peripheral blood is the most common source of CD34+ cells intended for transplantations. The collection and enrichment of CD34+ cells could be affected by various factors and there are some controversies regarding the effects of patient-related factors. The aim of this study was to assess the impact of age, sex, and diabetes on the CD34+ cell grafts in patients with chronic heart failure.

STUDY DESIGN AND METHODS

Cell grafts from 100 adult patients scheduled for autologous CD34+ cell transplantation were investigated. The CD34+ cells were collected using leukapheresis after granulocyte-colony-stimulating factor mobilization and further enriched using the immunomagnetic CD34+ selection. The number of CD34+ cells and their viability were determined by flow cytometry.

RESULTS

Older patients had significantly lower CD34+ cell counts than younger patients. The differences between men and women were not found. There was a trend toward an inverse relationship between diabetes and the CD34+ cell count, however, without any significance. No differences in the CD34+ cell viability (97.6% before and 97.9% after selection) were found. The mean CD34+ cell recovery was 59.7% and was not statistically different between age groups, sex, and diabetic patients.

CONCLUSION

Before the CD34+ cells are collected the patient's age should be considered. The study did not demonstrate a significant impact of sex and diabetes on the CD34+ cell count. While age and sex did not affect the immunoselection process, diabetes slightly reduced cell recovery. Cell viabilities before and after the cell enrichment were comparable between the tested samples.

The contralateral extremity has also benefit from the locally administered bone marrow-derived mononuclear cells and cord blood serum in diabetic ischemic wound healing

OBJECTIVE

Impaired wound healing could be a disaster especially in diabetes and amputation is the major risk. The aim of this study was to evaluate the benefit of BMMCs and CBS on wound healing.

METHODS

Diabetic rats were underwent bilateral limb ischemia and wounding of skin defects on both extremities. The groups were formed as BMMCs (group A), BMMCs and CBS (group B), only CBS (group C), and phosphate buffer solution (group D) that were injected into wounds on right legs.

RESULTS

The complete recovery of right legs was established as a mean of 21.4 ± 1.1 days, 12.9 ± 1.5 days, 30.0 ± 0.0 days and 38.1 ± 1.5 days according to Groups A, B, C, and D (p < 0.05). The recovery of left legs were calculated as a mean of 27.0 ± 0.0 days, 24.0 ± 0.0 days, 35.6 ± 1.1 days and 37.3 ± 1.6 days according to Groups A, B, C and D (p < 0.05). At the end of the recovery, the HE staining showed that vascularity was increased in groups A and B.

CONCLUSION

Transplantation of BMMCs and CBS to the ischemic wounds of the diabetic rats accelerate the repair. The recovery was also superior in the same group although the treatment was not applied to the left extremity directly.

Reduced levels of circulating endothelial progenitor cells in acute myocardial infarction patients with diabetes or pre-diabetes: accompanying the glycemic continuum

Background

Diabetic patients have a significantly worse prognosis after an acute myocardial infarction (AMI) than their counterparts. Previous studies have shown that the number of circulating endothelial progenitor cells (EPCs) significantly increase early after an AMI in normoglycemic patients. However, it is well known that type 2 diabetes mellitus (DM) is associated with impaired function and reduced circulating EPCs levels. Nonetheless, few studies have analyzed EPCs response of diabetics to an AMI and the EPC response of pre-diabetic patients has not been reported yet. Therefore, we hypothesized that in the acute phase of an AMI, diabetic and pre-diabetics have lower circulating EPCs levels than patients with normal glucose metabolism. We also evaluated the possible capacity of chronic antidiabetic treatment in the recovery of EPCs response to an AMI in diabetics.

Methods

One-hundred AMI patients were prospectively enrolled in the study. Using the high-performance flow cytometer FACSCanto II, circulating EPCs (CD45dimCD34+KDR+ and CD45dimCD133+KDR+ cells) were quantified, within the first 24 hours of admission. In addition, as an indirect functional parameter, we also analyzed the fraction of EPCs coexpressing the homing marker CXCR4.

Results

We found that in the acute phase of an AMI, diabetic patients presented significantly lower levels of circulating CD45dimCD34+KDR+ and CD45dimCD133+KDR+ EPCs by comparison with nondiabetics, with a parallel decrease in the subpopulations CXCR4+ (p < 0.001). Indeed, this study suggests that the impaired response of EPCs to an AMI is an early event in the natural history of DM, being present even in pre-diabetes. Our results, also demonstrated that numbers of all EPCs populations were inversely correlated with HbA1c (r = -0.432, p < 0.001 for CD45dimCD34+KDR+ cells). Finally, this study suggests that previous chronic insulin therapy (but not oral antidiabetic drugs) attenuate the deficient response of diabetic EPCs to an AMI.

Conclusion

This study indicates that there is a progressive decrease in EPCs levels, from pre-diabetes to DM, in AMI patients. Moreover, glycemic control seems to be determinant for circulating EPCs levels presented in the acute phase of an AMI and chronic insulin therapy may probably attenuate the deficit in EPCs pool seen in diabetics.

Umbilical cord blood-derived aldehyde dehydrogenase-expressing progenitor cells promote recovery from acute ischemic injury

Umbilical cord blood (UCB) represents a readily available source of hematopoietic and endothelial precursors at early ontogeny. Understanding the proangiogenic functions of these somatic progenitor subtypes after transplantation is integral to the development of improved cell-based therapies to treat ischemic diseases. We used fluorescence-activated cell sorting to purify a rare (<0.5%) population of UCB cells with high aldehyde dehydrogenase (ALDH(hi) ) activity, a conserved stem/progenitor cell function. ALDH(hi) cells were depleted of mature monocytes and T- and B-lymphocytes and were enriched for early myeloid (CD33) and stem cell-associated (CD34, CD133, and CD117) phenotypes. Although these cells were primarily hematopoietic in origin, UCB ALDH(hi) cells demonstrated a proangiogenic transcription profile and were highly enriched for both multipotent myeloid and endothelial colony-forming cells in vitro. Coculture of ALDH(hi) cells in hanging transwells promoted the survival of human umbilical vein endothelial cells (HUVEC) under growth factor-free and serum-free conditions. On growth factor depleted matrigel, ALDH(hi) cells significantly increased tube-like cord formation by HUVEC. After induction of acute unilateral hind limb ischemia by femoral artery ligation, transplantation of ALDH(hi) cells significantly enhanced the recovery of perfusion in ischemic limbs. Despite transient engraftment in the ischemic hind limb, early recruitment of ALDH(hi) cells into ischemic muscle tissue correlated with increased murine von Willebrand factor blood vessel and CD31+ capillary densities. Thus, UCB ALDH(hi) cells represent a readily available population of proangiogenic progenitors that promote vascular regeneration. This work provides preclinical justification for the development of therapeutic strategies to treat ischemic diseases using UCB-derived ALDH(hi) mixed progenitor cells.

Correlation between the functional impairment of bone marrow-derived circulating progenitor cells and the extend of coronary artery disease

Background

Bone marrow-derived circulating progenitor cells (BM-CPCs) in patients with coronary heart disease are impaired with respect to number and functional activity. However, the relation between the functional activity of BM-CPCs and the number of diseased coronary arteries is yet not known. We analyzed the influence of the number of diseased coronary arteries on the functional activity of BM-CPCs in peripheral blood (PB) in patients with ischemic heart disease (IHD).

Methods

The functional activity of BM-CPCs was measured by migration assay and colony forming unit in 120 patients with coronary 1 vessel (IHD1, n = 40), coronary 2 vessel (IHD2, n = 40), coronary 3 vessel disease (IHD3, n = 40) and in a control group of healthy subjects (n = 40). There was no significant difference of the total number of cardiovascular risk factors between IHD groups, beside diabetes mellitus (DM), which was significantly higher in IHD3 group compared to IHD2 and IHD1.

Results

The colony-forming capacity (CFU-E: p < 0.001, CFU-GM: p < 0.001) and migratory response to stromal cell-derived factor 1 (SDF-1: p < 0.001) as well as vascular endothelial growth factor (VEGF: p < 0001) of BM-CPCs were reduced in the group of patients with IHD compared to control group. The functional activity of BM-CPCs was significantly impaired in patients with IHD3 as compared to IHD1 (VEGF: p < 0.01, SDF-1: p < 0.001; CFU-E: p < 0.001, CFU-GM: p < 0.001) and to IHD2 (VEGF: p = 0.003, SDF-1: p = 0.003; CFU-E: p = 0.001, CFU-GM: p = 0.001). No significant differences were observed in functional activity of BM-CPCs between patients with IHD2 and IHD1 (VEGF: p = 0.8, SDF-1: p = 0.9; CFU-E: p = 0.1, CFU-GM: p = 0.1). Interestingly, the levels of haemoglobin AIc (HbAIc) correlated inversely with the functional activity of BM-CPCs (VEGF: p < 0.001, r = −0.8 SDF-1: p < 0.001, r = −0.8; CFU-E: p = 0.001, r = −0.7, CFU-GM: p = 0.001, r = −0.6) in IHD patients with DM.

Conclusions

The functional activity of BM-CPCs in PB is impaired in patients with IHD. This impairment increases with the number of diseased coronary arteries. Moreover, the regenerative capacity of BM-CPCs in ischemic tissue further declines in IHD patients with DM. Furthermore, monitoring the level of BM-CPCs in PB may provide new insights in patients with IHD.

Advanced glycation end products impair the migration, adhesion and secretion potentials of late endothelial progenitor cells

Background

Endothelial progenitor cells (EPCs), especially late EPCs, play a critical role in endothelial maintenance and repair, and postnatal vasculogenesis. Advanced glycation end products (AGEs) have been shown to impair EPC functions, such as proliferation, migration and adhesion. However, their role in the regulation of the production of vasoactive substances in late EPCs is less well defined.

Methods

Passages of 3~5 EPCs, namely late EPCs, were cultured with different concentrations (0~500 μg/ml) of AGEs, and the apoptosis, adhesion and migration were subsequently determined. The release of vasoactive substances, such as stromal cell-derived factor-1 (SDF-1), nitric oxide (NO), prostaglandin I₂ (PGI₂), plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator (tPA), and in addition the activity of superoxide dismutase (SOD), were evaluated by ELISA. At the same time, the gene and protein expressions of CXCR4 were assayed by real-time RT-PCR and western-blot.

Results

AGEs promoted late EPC apoptosis. Moreover, AGEs impaired late EPC migration and adhesion in a concentration-dependent manner. Accordingly, the production of SDF-1 was decreased by AGEs. Although the CXCR4 expressions of late EPCs were up-regulated for AGE concentrations of 50, 100 or 200 μg/ml, a marked decrease was observed for the higher concentration of 500 μg/ml. Furthermore, co-culturing with AGEs decreased the levels of NO, t-PA, PGI_2, and the activity of SOD but up-regulated the production of PAI-1.

Conclusion

Our data provide evidence that AGEs play an important role in impairing late EPC functions, which could contribute to the development of vascular diseases in diabetes.

Vascular stem cells in diabetic complications: evidence for a role in the pathogenesis and the therapeutic promise

Long standing diabetes leads to structural and functional alterations in both the micro- and the macro-vasculature. Vascular endothelial cells (ECs) are the primary target of the hyperglycemia-induced adverse effects. Vascular stem cells that give rise to endothelial progenitor cells (EPCs) and mesenchymal progenitor cells (MPCs) represent an attractive target for cell therapy for diabetic patients. A number of studies have reported EPC dysfunction as a novel participant in the culmination of the diabetic complications. The controversy behind the identity of EPCs and the similarity between these progenitor cells to hematopoietic cells has led to conflicting results. MPCs, on the other hand, have not been examined for a potential role in the pathogenesis of the complications. These multipotent cells, however, do show a therapeutic role. In this article, we summarize the vascular changes that occur in diabetic complications highlighting some of the common features, the key findings that illustrate an important role of vascular stem cells (VSCs) in the pathogenesis of chronic diabetic complications, and provide mechanisms by which these cells can be used for therapy.

The possible role of ribosomal protein S6 kinase 4 in the senescence of endothelial progenitor cells in diabetes mellitus

Background

The decrease and dysfunction of endothelial progenitor cells (EPCs) has been assumed as an important cause/consequence of diabetes mellitus (DM) and its complications, in which the senescence of EPCs induced by hyperglycemia may play an immensurable role. However, the mechanisms of EPCs senescence has not been fully investigated. Recently, ribosomal protein S6 kinase 4 (RSK4), a member of serine/threomine (Ser/Thr) kinase family and p53-related gene, is reported to regulate the replicative and stress-induced senescence of different cells.

Presentation of the hypothesis

These above lead to consideration of an evidence-based hypothesis that RSK4 may serve as a mediator of EPCs senescence in DM.

Testing the hypothesis

EPCs of healthy subjects and DM patients are isolated from peripheral blood and incubated with high glucose (HG). Then, the EPCs senescence would be detected by senescence associated β-galactosides (SA-β-gal) staining. Meanwhile, the RSK4 expression is assessed by RT-PCR and western blot. Moreover, overexpressing or RNA interfering of RSK4 in EPCs to investigate the relationship between RSK4 expression and the senescence of EPCs are necessary to substantiate this hypothesis. Also, studies on possible upstream and downstream factors of RSK4 would be explored to reveal the RSK4-mediated senescence pathway in EPCs.

Implications of the hypothesis

If proved, this hypothesis will provide another mediator of EPCs senescence, and may establish a novel pathogenesis for DM and further benefit to the management of DM.