Elsevier

Microvascular Research

Volume 81, Issue 2, March 2011, Pages 216-221
Microvascular Research

Regular Article
Circulating endothelial and endothelial progenitor cells in patients with severe sepsis

https://doi.org/10.1016/j.mvr.2010.11.011Get rights and content

Abstract

Elevated circulating endothelial cell (CEC) and circulating endothelial progenitor cell (CEPC) counts may indicate vascular damage and disease status, but data on these cell populations in patients with severe sepsis are limited. This study compared CEC and CEPC counts in patients with and without severe sepsis following intensive care unit (ICU) admission. Venous blood samples were collected within 24 h, 48–72 h, and 120–144 h. Baseline demographics, 28-day mortality, ICU and hospital days, and Sequential Organ Failure Assessment (SOFA) scores were recorded. Patients with (n = 18) and without (n = 28) severe sepsis were balanced for mean age (63.7 and 61.3 years, respectively) and gender. There were no differences in 28-day mortality, ICU days, or hospital days. Baseline SOFA scores were higher in the sepsis group. At 48–72 h, patients with severe sepsis had significantly higher median CEC counts (51.5 vs. 28.0 cells/4 ml of blood, P = 0.02). CEC values for all ICU patients were significantly (P < 0.05) higher than in healthy volunteers. CEPC counts in both cohorts ranged from 0 to > 21 colonies/4 ml blood (mean = 1.13 ± 2.25; median = 0) without significant differences at any time point. This study demonstrates the ability to quantify CECs and CEPCs using consensus methodology. Understanding the relationship between CEC/CEPC counts and outcomes may provide insight into the mechanisms of endothelial cell changes in severe sepsis.

Graphical abstract

Comparison of circulating endothelial cell counts between patients in the intensive care unit with severe sepsis compared to patients without sepsis was similar except at 48–72 h post-baseline when the severe sepsis cohort showed significantly higher counts providing insight into the mechanism of microvascular changes in severe sepsis.

  1. Download : Download full-size image

Research Highlights

► Patients in intensive care, with and without severe sepsis, had significant elevations in circulating endothelial cell counts compared to healthy volunteers. ► Consensus methodology using immunomagnetic separation demonstrated the ability to quantify circulating endothelial and circulating endothelial progenitor cells. ► Positive correlation between improvement in organ function as measured by Sequential Organ Failure Assessment (SOFA) scores and baseline circulating endothelial progenitor cells.

Introduction

Severe sepsis, defined as sepsis associated with acute organ dysfunction (Levy et al., 2003), involves a complicated host response including activation of several cell types, inflammatory mediators, and coagulation factors. One of the hallmarks is microvascular damage, in which endothelial activation and dysfunction play a pivotal role (Aird, 2003, Bateman et al., 2003). Endothelial cells undergo changes in function and structure resulting in detachment from the vessel wall and subsequent appearance in the circulation (Aird, 2003, Boos et al., 2006).

The presence of circulating endothelial cells (CECs) in peripheral blood of healthy individuals is rare. Their numbers increase in a variety of conditions such as cardiovascular disease, cancer, infection, and inflammatory states (Dignat-George et al., 2003) including septic shock (Mutunga et al., 2001) where they serve as indicators of vascular damage. In the last decade, CEC counts have emerged as an index of assessing endothelial damage or dysfunction (Blann et al., 2005).

Circulating endothelial progenitor cells (CEPCs), which may arise in the bone marrow and appear in peripheral blood, are thought to be recruited in response to vascular trauma (Dignat-George et al., 2003). Increased numbers of CEPCs have been reported in conditions characterized by vascular injury, where a correlation has been shown between number of CEPCs and extent of endothelial damage (George et al., 1992, Strijbos et al., 2009, Woywodt et al., 2006). These cells have high proliferative potential and may function to replace endothelial cells destroyed by pathological processes like those in severe sepsis.

Despite increasing knowledge about CECs and CEPCs in vascular disease, there are few studies of patients with severe sepsis. One study demonstrated increased CEC counts in patients with severe sepsis compared to healthy volunteers and intensive care unit (ICU) patients without sepsis, providing direct evidence of endothelial damage during sepsis (Mutunga et al., 2001). Two other studies showed increased CEPCs in the blood of patients with sepsis compared to healthy controls (Becchi et al., 2008, Rafat et al., 2007). These studies, however, used different methods for identification and quantification of CECs and CEPCs than the current study, which used a Food and Drug Administration (FDA)-approved automated system to accurately and reliably enumerate CECs and an in vitro culture assay for the assessment of endothelial colony forming cells (ECFCs) that display all the properties of CEPCs (Yoder, 2009).

This study's primary objective was to compare the number of CECs in patients with severe sepsis to those in patients without severe sepsis at three time points to investigate the kinetics of the endothelial response. Secondary objectives included quantifying the number of CEPCs in the same patients and correlating CEC and CEPC counts with Sequential Organ Failure Assessment (SOFA) scores and outcomes (28-day mortality, length of ICU stay, or length of hospital stay). Understanding the relationship between CEC/CEPC levels and outcomes may provide insight into the mechanisms of endothelial cell changes in severe sepsis and lead to targeted therapy.

Section snippets

Methods

This was a nontherapeutic, observational study with patients enrolled between August 2007 and March 2009 at 3 hospitals in the United States. Hospitals included: Methodist Hospital (Indianapolis, IN), a 725-bed academic teaching hospital with 131 adult mixed medical and surgical ICU beds; Massachusetts General Hospital (Boston, MA), a 1000-bed quaternary referral center and teaching hospital affiliated with Harvard Medical School, with an 18-bed medical ICU and 16-bed coronary ICU; and

Patient data

Forty-six patients (18 in severe sepsis cohort and 28 in non-sepsis cohort) admitted to the ICU were enrolled into the study. No significant demographic differences between the cohorts were noted other than difference in the individual cardiology, renal, and neurology SOFA scores (Table 1).

Patients in the severe sepsis cohort met the following inclusion criteria: presence of a suspected or proven infection, and presence of ≥ 2 sepsis-associated organ dysfunctions. Patients in the non-sepsis

Discussion

This is the first study to evaluate CEC counts and CEPC culture assays in ICU patients with severe sepsis compared to ICU patients without sepsis. It is also the first study in these patients to use reliable methods and a consensus definition to identify the cells. Observed was an increase in CECs in the two cohorts when compared to established normal values in healthy volunteers. When compared to each other, CEC counts in both cohorts were similar except at 48–72 h, when they were

Acknowledgments

The authors would like to thank Barb Utterback of Eli Lilly and Company for project management, and Maryann Weller, Caron Modeas, and Joseph Durrant of i3Statprobe for writing and editorial assistance.

References (19)

There are more references available in the full text version of this article.

Cited by (27)

  • Endothelial progenitor cells in the host defense response

    2023, Pharmacology and Therapeutics
    Citation Excerpt :

    Normally, EPCs are very rare in the systemic circulation. In humans, it has been reported that peripheral blood samples contain EPCs at 0.41 ± 0.47 colony-forming units (CFUs)/4 ml blood as analyzed by cell culture (Schlichting et al., 2011) and 2.70 ± 0.73 CD34+KDR+ cells/104 peripheral blood mononuclear cells as determined with flow cytometry (Zhu et al., 2021). In both adult and pediatric patients with septic infection, the level of EPCs in the circulation has been repeatedly reported to increase (Becchi et al., 2008; Kung et al., 2016; Patschan et al., 2011; Rafat et al., 2007a, 2007b; Siavashi et al., 2017; Zahran, Elsayh, Mohamad, Hassan, & Abdou, 2016).

  • Endothelial-to-mesenchymal transition: Cytokine-mediated pathways that determine endothelial fibrosis under inflammatory conditions

    2017, Cytokine and Growth Factor Reviews
    Citation Excerpt :

    Taking into account that developing cell-to-cell adhesion proteins, such as VE-cad and CD31, are lost during EndMT, it is possible that fibrotic endothelial cell detachment contributes to cancer metastasis [11,63,80,82]. Regarding metastasis, special attention has been paid to EndMT in endothelial progenitor cells, which increases in serum during severe systemic inflammation [83–85]. Furthermore, endothelial progenitor cells exposed to conditioned media can migrate and enhance ovarian cancer through a TGF-β-mediated mechanism [86].

  • Circulating endothelial progenitor cells may predict outcomes in adult patients with severe sepsis in the emergency department

    2016, Clinica Chimica Acta
    Citation Excerpt :

    Recently, evidence has shown impaired EPC proliferation in patients with macrovascular damage such as coronary artery and cerebrovascular disease [11–14]. Several research groups have investigated EPCs in sepsis; however, their role has not yet been unequivocally defined [15–22]. Observational studies have shown an increased percentage of circulating EPCs, enumerated by flow cytometry, in heterogeneous patients with sepsis [15,19,20], whereas experimental studies in a multi-organ dysfunction syndrome (MODS) model in pigs and in healthy volunteers administered lipopolysaccharide have shown decreased numbers [17,18].

  • Endocan is useful biomarker of survival and severity in sepsis

    2014, Microvascular Research
    Citation Excerpt :

    In sepsis, the activation of endothelial cells by mediators of infection such as lipopolysaccharide (LPS) in Gram-negative or lipoteichoic acid in Gram-positive infections, or cytokines, for instance interleukin-1-beta (IL-1 β) and tumor necrosis factor-alpha (TNF- α), result in a complex proinflammatory and prothrombotic phenotype (Harlen, 2010). Endothelial cells express many molecules involved in pathophysiological processes in sepsis (Schlichting et al., 2011.), and one of these molecules is endothelial cell specific molecule-1 (endocan) (Bechard et al., 2001).

  • Circulating hematopoietic and endothelial progenitor cells in newborn infants: Effects of gestational age, postnatal age and clinical stress in the first 3weeks of life

    2013, Early Human Development
    Citation Excerpt :

    Experimental studies have shown that intravenous infusion of bone marrow derived or peripheral blood derived endothelial progenitor cells (EPC) attenuates endotoxin induced acute lung injury [5,6] and improves survival [6] in animal models. In human adults, increases in circulating EPC are described with bacterial pneumonia [7], severe sepsis [8], and following acute ischemic stroke [9]. Furthermore, increases in circulating EPC in patients with acute lung injury was associated with improved survival outcome [10].

View all citing articles on Scopus
View full text