Neuromuscular electrical stimulation acutely mobilizes endothelial progenitor cells in critically ill patients with sepsis

Background: Endothelial progenitor cells (EPCs) have been suggested to constitute a restoration index of the disturbed endothelium in ICU patients. Neuromuscular electric stimulation (NMES) is increasingly employed in ICU to prevent comorbidities such as ICU-acquired weakness, which is related to endothelial dysfunction. The role of NMES to mobilize EPCs has not been investigated yet. The purpose of this study was to explore the NMES-induced effects on mobilization of EPCs in septic ICU patients. Methods: Thirty-two septic mechanically ventilated patients (mean +/- SD, age 58 +/- 14 years) were randomized to one of the two 30-min NMES protocols of different characteristics: a high-frequency (75 Hz, 6 s on-21 s off) or a medium-frequency (45 Hz, 5 s on-12 s off) protocol both applied at maximally tolerated intensity. Blood was sampled before and immediately after the NMES sessions. Different EPCs subpopulations were quantified by cytometry markers CD34(+)/CD133(+)/CD45(-), CD34(+)/CD133(+)/CD45(-)/VEGFR(2)(+) and CD34(+)/CD45(-)/VEGFR(2)(+). Results: Overall, CD34(+)/CD133(+)/CD45(-) EPCs increased from 13.5 +/- 10.2 to 20.8 +/- 16.9 and CD34(+)/CD133(+)/CD45(-)/VEGFR(2)(+) EPCs from 3.8 +/- 5.2 to 6.4 +/- 8.5 cells/10(6) enucleated cells (mean +/- SD, p < 0.05). CD34(+)/CD45(-)/VEGFR(2)(+) EPCs also increased from 16.5 +/- 14.5 to 23.8 +/- 19.2 cells/10(6) enucleated cells (mean +/- SD, p < 0.05). EPCs mobilization was not affected by NMES protocol and sepsis severity (p > 0.05), while it was related to corticosteroids administration (p < 0.05). Conclusions: NMES acutely mobilized endothelial progenitor cells, measures of the endothelial restoration potential, in septic ICU patients.