Extracellular Vesicle-Derived microRNAs of Human Wharton's Jelly Mesenchymal Stromal Cells May Activate Endogenous VEGF-A to Promote Angiogenesis.

Cinzia Maria Chinnici,Pier Giulio Conaldi,Ettore Cittadini,Nicola Cuscino,Anna Paola Carreca,David Nascari,Giandomenico Amico,Francesca Timoneri,Mariangela Di Bella,Gioacchin Iannolo,Claudia Carcione

doi:10.3390/ijms22042045

Abstract

Despite low levels of vascular endothelial growth factor (VEGF)-A, the secretome of human Wharton’s jelly (WJ) mesenchymal stromal cells (MSCs) effectively promoted proangiogenic responses in vitro, which were impaired upon the depletion of small (~140 nm) extracellular vesicles (EVs). The isolated EVs shared the low VEGF-A profile of the secretome and expressed five microRNAs, which were upregulated compared to fetal dermal MSC-derived EVs. These upregulated microRNAs exclusively targeted the VEGF-A gene within 54 Gene Ontology (GO) biological processes, 18 of which are associated with angiogenesis. Moreover, 15 microRNAs of WJ-MSC-derived EVs were highly expressed (Ct value ≤ 26) and exclusively targeted the thrombospondin 1 (THBS1) gene within 75 GO biological processes, 30 of which are associated with the regulation of tissue repair. The relationship between predicted microRNA target genes and WJ-MSC-derived EVs was shown by treating human umbilical-vein endothelial cells (HUVECs) with appropriate doses of EVs. The exposure of HUVECs to EVs for 72 h significantly enhanced the release of VEGF-A and THBS1 protein expression compared to untreated control cells. Finally, WJ-MSC-derived EVs stimulated in vitro tube formation along with the migration and proliferation of HUVECs. Our findings can contribute to a better understanding of the molecular mechanisms underlying the proangiogenic responses induced by human umbilical cord-derived MSCs, suggesting a key regulatory role for microRNAs delivered by EVs.

Highlights

After reaching 80% confluence, mesenchymal stromal cells (MSCs) were transferred to 75 cm2 plastic tissue flasks and subcultured every 4 days before undergoing growth arrest after 8–10 passages
The umbilical cord holds the promise of an accessible source of MSCs with the potential to reverse those clinical conditions where angiogenesis is impaired
“small” extracellular vesicles (EVs) are described as important contributors of Wharton’s jelly (WJ)-MSC-mediated proangiogenic responses

Summary

Introduction

The activation of tissue repair requires the participation of multiple biological processes such as cell recruitment, proliferation, tissue remodeling, immune reactions, apoptosis and angiogenesis [1,2]. Angiogenesis is a highly regulated dynamic process involving multiple cell types and signaling pathways. The angiogenic response has been attributed in part to several angiogenic regulators, such as growth factors and chemokines, which can be released by mesenchymal stromal cells (MSCs) and are thought to be responsible for the clinical outcomes of MSC-based therapy [4,5,6]. A mechanism of secretion of these molecules involves their export into extracellular vesicles (EVs), important mediators of intercellular communication through the release on their cargo molecules [7,8].

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Results

Conclusion