Circulating endothelial progenitor cells are not affected by acute systemic inflammation

Area of Science:

• Cardiovascular Biology
• Immunology
• Hematology

Background:

• Vascular injury triggers systemic inflammation and mobilizes endothelial progenitor cells (EPCs) and endothelial cell colony-forming units (EC-CFUs).
• The precise role of systemic inflammation in EPC and EC-CFU mobilization, whether specific to vascular injury or a general response, remains unclear.

Purpose of the Study:

• To investigate the effect of acute systemic inflammation on EPC and EC-CFU mobilization independently of vascular injury.
• To utilize Salmonella typhus vaccination as a model for inducing acute systemic inflammation in healthy volunteers.

Main Methods:

• A double-blind randomized crossover study involving 12 healthy volunteers receiving S. typhus vaccination or placebo.
• Quantification of phenotypic EPC populations (e.g., CD34(+)VEGF receptor (VEGF)R-2(+)CD133(+), CD14(+)VEGFR-2(+)Tie2(+), CD45(-)CD34(+), CD34(+)CXCR-4(+)) via flow cytometry.
• Measurement of EC-CFUs and serum cytokine concentrations (high sensitivity C-reactive protein, IL-6, stromal-derived factor-1) over 7 days.

Main Results:

• Vaccination significantly increased circulating leukocytes, IL-6, VEGF-A, and high sensitivity C-reactive protein levels.
• A notable increase in CD14(+) cells (56.7%) at 6 hours and CD34(+) cells (22.4%) at 7 days was observed post-vaccination.
• Crucially, EC-CFUs and serum stromal-derived factor-1 concentrations remained unaffected, indicating no selective mobilization of vascular progenitors.

Conclusions:

• Acute systemic inflammation induces a nonspecific mobilization of hematopoietic progenitor cells.
• This inflammation does not selectively mobilize putative vascular progenitor cells (EC-CFUs).
• Systemic inflammation is unlikely to be the primary stimulus for EPC mobilization following acute vascular injury.