Endothelial progenitor cells mobilization after maximal exercise according to heart failure severity

BACKGROUND

Vascular endothelial dysfunction is an underlying pathophysiological feature of chronic heart failure (CHF). Patients with CHF are characterized by impaired vasodilation and inflammation of the vascular endothelium. They also have low levels of endothelial progenitor cells (EPCs). EPCs are bone marrow derived cells involved in endothelium regeneration, homeostasis, and neovascularization. Exercise has been shown to improve vasodilation and stimulate the mobilization of EPCs in healthy people and patients with cardiovascular comorbidities. However, the effects of exercise on EPCs in different stages of CHF remain under investigation.

AIM

To evaluate the effect of a symptom-limited maximal cardiopulmonary exercise testing (CPET) on EPCs in CHF patients of different severity.

METHODS

Forty-nine consecutive patients (41 males) with stable CHF [mean age (years): 56 ± 10, ejection fraction (EF, %): 32 ± 8, peak oxygen uptake (VO₂, mL/kg/min): 18.1 ± 4.4] underwent a CPET on a cycle ergometer. Venous blood was sampled before and after CPET. Five circulating endothelial populations were quantified by flow cytometry: Three subgroups of EPCs [CD34⁺/CD45^-/CD133⁺, CD34⁺/CD45^-/CD133⁺/VEGFR₂ and CD34⁺/CD133⁺/vascular endothelial growth factor receptor 2 (VEGFR₂)] and two subgroups of circulating endothelial cells (CD34⁺/CD45^-/CD133^- and CD34⁺/CD45^-/CD133^-/VEGFR₂). Patients were divided in two groups of severity according to the median value of peak VO₂ (18.0 mL/kg/min), predicted peak VO₂ (65.5%), ventilation/carbon dioxide output slope (32.5) and EF (reduced and mid-ranged EF). EPCs values are expressed as median (25th-75th percentiles) in cells/10⁶ enucleated cells.

RESULTS

Patients with lower peak VO₂ increased the mobilization of CD34⁺/CD45^-/CD133⁺ [pre CPET: 60 (25-76) vs post CPET: 90 (70-103) cells/10⁶ enucleated cells, P < 0.001], CD34⁺/CD45^-/CD133⁺/VEGFR₂ [pre CPET: 1 (1-4) vs post CPET: 5 (3-8) cells/10⁶ enucleated cells, P < 0.001], CD34⁺/CD45^-/CD133^- [pre CPET: 186 (141-361) vs post CPET: 488 (247-658) cells/10⁶ enucleated cells, P < 0.001] and CD34⁺/CD45^-/CD133^-/VEGFR₂ [pre CPET: 2 (1-2) vs post CPET: 3 (2-5) cells/10⁶ enucleated cells, P < 0.001], while patients with higher VO₂ increased the mobilization of CD34⁺/CD45^-/CD133⁺ [pre CPET: 42 (19-73) vs post CPET: 90 (39-118) cells/10⁶ enucleated cells, P < 0.001], CD34⁺/CD45^-/CD133⁺/VEGFR₂ [pre CPET: 2 (1-3) vs post CPET: 6 (3-9) cells/10⁶ enucleated cells, P < 0.001], CD34⁺/CD133⁺/VEGFR₂ [pre CPET: 10 (7-18) vs post CPET: 14 (10-19) cells/10⁶ enucleated cells, P < 0.01], CD34⁺/CD45^-/CD133^- [pre CPET: 218 (158-247) vs post CPET: 311 (254-569) cells/10⁶ enucleated cells, P < 0.001] and CD34⁺/CD45^-/CD133^-/VEGFR₂ [pre CPET: 1 (1-2) vs post CPET: 4 (2-6) cells/10⁶ enucleated cells, P < 0.001]. A similar increase in the mobilization of at least four out of five cellular populations was observed after maximal exercise within each severity group regarding predicted peak, ventilation/carbon dioxide output slope and EF as well (P < 0.05). However, there were no statistically significant differences in the mobilization of endothelial cellular populations between severity groups in each comparison (P > 0.05).

CONCLUSION

Our study has shown an increased EPCs and circulating endothelial cells mobilization after maximal exercise in CHF patients, but this increase was not associated with syndrome severity. Further investigation, however, is needed.

A cardiac rehabilitation program increases the acute respond of endothelial progenitor cells after maximum exercise in patients with chronic heart failure

Background

Chronic heart failure (CHF) remains a leading cause of morbidity and mortality and it is characterized by vascular endothelial dysfunction. During the last decades, endothelial progenitor cells (EPCs) are being used as an index of the endothelium restoration potential, therefore reflecting the vascular endothelial function. Exercise training has been shown to stimulate the mobilization of EPCs at rest in CHF patients. However, the effect of exercise training on the acute respond of EPCs after maximum exercise in CHF patients remains unknown.

Purpose

The purpose of the study was to assess the effect of a cardiac rehabilitation (CR) program on the acute respond of EPCs after maximum exercise in patients with CHF.

Methods

Forty-four consecutive patients (35 males) with stable CHF [mean±SD, Age (years): 56±10, BMI (kg/m2): 28.7±5.2, EF (%): 33±8, Peak VO2 (ml/kg/min): 18.4±4.4, Peak work rate (watts): 101±39] enrolled a 36-session CR program based on high-intensity interval exercise training. All patients underwent an initial symptom limited maximal cardiopulmonary exercise testing (CPET) on an ergometer before the CR program and a final maximal CPET after the CR program. Venous blood was drawn before and after each CPET. Five circulating endothelial populations were identified and quantified by flow cytometry; CD34+/CD45-/CD133+, CD34+/CD45-/CD133+/VEGFR2, CD34+/CD133+/VEGFR2, CD34+/CD45-/CD133- and CD34+/CD45-/CD133-/VEGFR2. EPCs values are expressed as cells/million enucleated cells in medians (25th-75th percentiles).

Results

The acute mobilization of EPCs after the final CPET was higher than after the initial CPET in 4 out of 5 circulating endothelial populations. Most specifically, difference of the acute mobilization of CD34+/CD45-/CD133+ cells [initial CPET: 25 (15–46) vs final CPET: 49 (26–71), p=0.002], CD34+/CD45-/CD133+/VEGFR2 cells [initial CPET: 3 (2–5) vs final CPET: 8 (5–12), p&lt;0.001], CD34+/CD45-/CD133- cells [initial CPET: 129 (52–338) vs final CPET: 250 (129–518), p=0.03] and CD34+/CD45-/CD133-/VEGFR2 cells [initial CPET: 2 (1–4) vs final CPET: 6 (3–9), p&lt;0.001] increased after the final CPET. The acute mobilization of CD34+/CD133+/VEGFR2 cells [initial CPET: 3 (−1–7) vs final CPET: 5 (0–15), p=0.441] did not differ between the 2 CPETS.

Conclusion

A 36-session cardiac rehabilitation program increases the acute respond of endothelial progenitor cells after maximum cardiopulmonary exercise training in patients with chronic heart failure, therefore indicating the beneficial effect of exercise training on the vascular endothelial function.

Funding Acknowledgement

Type of funding source: Public grant(s) – EU funding. Main funding source(s): Co-financed by Greece and the European Union (European Social Fund- ESF) through the Operational Programme “Human Resources Development, Education and Lifelong Learning” in the context of the project

P753Exercise has similar beneficial effect in the mobilization of endothelial progenitor cells in patients with chronic heart failure of different severity

Introduction

Vascular endothelial dysfunction is an underlying pathophysiological feature of chronic heart failure (CHF). Exercise has been shown to stimulate the mobilization of endothelial progenitor cells (EPC) in healthy populations. EPC contribute to the regeneration of the inflammatory endothelium and promote neovascularization.

Purpose

The purpose of the present study was to investigate the mobilization of EPC between CHF patients with different severity after a 36-session exercise training program.

Methods

Thirty eight consecutive patients (32 ♂, 6 ♀) with stable CHF [mean±SD, age (years): 56±10, EF (%): 32±9, peak VO2 (ml/kg/min): 18.1±4.1] enrolled a 36-session exercise training program. All patients underwent a symptom limited maximal cardiopulmonary exercise testing (CPET) on a cycle ergometer before and after the training program. Venous blood was sampled before and after each CPET. Five endothelial circulating populations were quantified by flow cytometry (Table 1). Patients were divided in severity groups according to the median values of peak VO2, predicted peak VO2, VE/VCO2 slope and EF. EPC values are expressed as “cells/million enucleated cells” in medians (25th, 75th percentiles).

Results

In all patients, rehabilitation showed a statistical significant effect as well as a significant acute effect in all endothelial circulating populations (p<0.001). Although there was statistical significant mobilization of endothelial circulating populations within each severity group (groups separated by peak VO2), no differences were observed between groups (p>0.05, Table 1). Similar results were also shown for the rest of CPET parameters and EF.

Cellular populations in severity groups Endothelial cellular populations Peak VO2 <18 ml/kg/min Peak VO2 ≥18 ml/kg/min Before rehabilitation After rehabilitation Before rehabilitation After rehabilitation Before CPET After CPET Before CPET After CPET Before CPET After CPET Before CPET After CPET CD34+/CD45–/CD133+ 54 (24–74) 90 (40–104)* 96 (54–120) 154 (100–169)* 37 (16–66) 60 (33–93)* 79 (46–106) 122 (96–159)* CD34+/CD45–/CD133+/VEGFR2 1 (1–3) 3 (2–8)* 8 (4–9) 14 (10–19)* 2 (1–3) 4 (3–8)* 5 (4–7) 13 (9–16)* CD34+/CD133+/VEGFR2 13 (8–18) 13 (9–25) 22 (16–31) 27 (14–38) 10 (7–19) 14 (9–20)** 16 (13–37) 22 (15–62)** CD34+/CD45–/CD133– 186 (131–368) 494 (202–640)* 431 (301–564) 738 (590–921)* 214 (150–270) 306 (233–575)* 434 (277–835) 740 (524–1588)* CD34+/CD45–/CD133–/VEGFR2 2 (1–2) 3 (2–5)* 4 (3–5) 10 (9–14)* 1 (1–1) 3 (2–5)* 4 (2–8) 9 (7–12)* Differences within groups *p<0.001, **p<0.05.

Conclusion

A 36-session training program stimulates the long term mobilization of EPC in CHF patients. This mobilization seems to be similar in all patients irrespective of their severity. The clinical relevance of these findings and the potential mechanisms need further investigation.

Acknowledgement/Funding

Greece and the European Union (European Social Fund-ESF) through the Operational Programme “Human Resources Development, Education, Lifelong Learning”