Platelets of Healthy Origins Promote Functional Improvement of Atherosclerotic Endothelial Progenitor Cells.

Nicoleta Alexandru,Florentina Safciuc,Gabriela Tanko,Emanuel Dragan,Elisabeta Bãdilã,Alina Constantin,Adriana Georgescu,Miruna Nemecz,Alexandru Filippi

doi:10.3389/fphar.2019.00424

Abstract

The purpose was to evaluate the effect of platelets on functional properties of late endothelial progenitor cells (EPCs), in the direct co-culture conditions, and to investigate the involved mediators, in experimental induced atherosclerosis. The late EPCs obtained from two animal groups, hypertensive-hyperlipidemic (HH) and control (C) hamsters, named late EPCs-HH and late EPCs-C, were co-incubated with or without platelets isolated from both groups. Our results have showed that exposure to platelets from control animals: (i) promoted the late EPCs-C capacity to form colonies and capillary-like structures, and also to proliferate and migrate; (ii) improved the functional properties of late EPCs-HH; (iii) strengthened the direct binding EPCs-platelets; (iv) increased SDF-1α,VEGF, PDGF, and reduced CD40L, IL-1β,-6,-8 levels; and (v) enhanced miR-223 and IGF-1R expressions. Platelets from HH group diminished functional abilities for both EPC types and had opposite effects on these pro-angiogenic and pro-inflammatory molecules. Furthermore, testing the direct effect of miR-223 and IGF-1R on late EPCs disclosed that these molecular factors improve late EPC functional properties in atherosclerosis in terms of stimulation of the proliferation and migration abilities. In conclusion, in vitro exposure to platelets of healthy origins had a positive effect on functional properties of atherosclerotic late EPCs. The most likely candidates mediating EPC-platelet interaction can be SDF-1α, VEGF, CD40L, PDGF, IL-1β,-6,-8, miR-223, and IGF-1R. The current study brings evidences that the presence of healthy origin platelets is of utmost importance on functional improvement of EPCs in atherosclerosis.

Highlights

Endothelial progenitor cells (EPCs) represent a heterogeneous cell population derived from circulating CD34 positive or CD34 and kinase insert domain receptor (KDR)/vascular endothelial growth factor (VEGF) receptor-2 (KDR/vascular endothelial growth factor receptor 2 (VEGFR2)) double positive mononuclear cells (MNCs) (Zhang et al, 2013)
Immunofluorescence detection of CD34, KDR, C133, CD144, von Willebrand factor (vWF), Tie-2, CD14, and CD45 by flow cytometry revealed similar percentages to those found at late EPCs alone, meaning that the cells after incubation still maintain their ability to differentiate into mature cells as described by Alexandru et al (2017a)
In an attempt to demonstrate the direct interaction of platelets with late EPCs, we incubated late EPCs-C or late EPCs-hypercholesterolemic hamster (HH) stained with DAPI solution with platelets from C (PLTs-C) or HH (PLTs-HH) groups labeled with PKH26, for 7 days (Figure 1)

Summary

Introduction

Endothelial progenitor cells (EPCs) represent a heterogeneous cell population derived from circulating CD34 positive or CD34 and KDR/VEGF receptor-2 (KDR/VEGFR2) double positive MNCs (Zhang et al, 2013). EPCs are an angiogenic EPC population obtained from short-term cultures of 4–7 days, in vitro. These cells form colony forming units (CFUs) and possess many endothelial characteristics, such as harboring CD31, TIE2, and VEGFR2 markers (Asahara et al, 1997). Late EPCs possess in addition to early EPC specific markers, other endothelial characteristics, such as VE-cadherin and vWF (Shantsila et al, 2007). These cells can further differentiate into mature endothelial cells and are capable of forming new blood vessels through a process of vasculogenesis (Lee and Poh, 2014)

Methods

Results

Conclusion