Amniotic fluid stem cell-derived vesicles protect from VEGF-induced endothelial damage

S Sedrakyan,S Da Sacco,V Villani,N Tripuraneni,A Achena,A Petrosyan,B Bussolati,H Soloyan,M Lavarreda-Pearce,L Perin,S Porta,R E De Filippo

doi:10.1038/s41598-017-17061-2

Abstract

Injection of amniotic fluid stem cells (AFSC) delays the course of progression of renal fibrosis in animals with Alport Syndrome, enhancing kidney function and improving survival. The mechanisms responsible for these protective outcomes are still largely unknown. Here, we showed that vascular endothelial growth factor (VEGF) signaling within the glomeruli of Alport mice is strongly elevated early on in the disease, causing glomerular endothelial cell damage. Intraventricular injected AFSC that homed within the glomeruli showed strong modulation of the VEGF activity, particularly in glomerular endothelial cells. To investigate this phenomenon we hypothesized that extracellular vesicles (EVs) produced by the AFSC could be responsible for the observed renoprotection. AFSC derived EVs presented exosomal and stem cell markers on their surface membrane, including VEGFR1 and VEGFR2. EVs were able to modulate VEGF in glomerular endothelial cells by effectively trapping the excess VEGF through VEGFR1-binding preventing cellular damage. In contrast, VEGFR1/sVEGFR1 knockout EVs failed to show similar protection, thus indicating that VEGF trapping is a potentially viable mechanism for AFSC-EV mediated renoprotection. Taken together, our findings establish that EVs secreted by AFSC could target a specific signaling pathway within the glomerulus, thus representing a new potential glomerulus-specific targeted intervention.

Highlights

The complex local autocrine/paracrine signaling between podocytes and glomerular endothelial cells (GEC) is of critical importance for the homeostatic balance of the filtration barrier[1]
We previously demonstrated that stem cells derived from amniotic fluid (AFSC) are renoprotective and significantly delayed disease progression in a mouse model of Alport Syndrome (AS, where a mutation in any of the collIVα3,α4,α5 genes results in the disruption of the glomerular basement membrane (GBM), podocyte effacement and renal failure) via preservation of podocyte number and maintenance of glomerular function[12]
We confirmed that amniotic fluid stem cells (AFSC) release extracellular vesicles (EVs) that express various surface markers, including VEGFR1 and VEGF receptor 2 (VEGFR2), and can modulate vascular endothelial growth factor (VEGF)/VEGFRs signaling in damaged GEC by decreasing the bio-availability of excess VEGF

Summary

Introduction

The complex local autocrine/paracrine signaling between podocytes and glomerular endothelial cells (GEC) is of critical importance for the homeostatic balance of the filtration barrier[1]. The renoprotection by AFSC could possibly be ascribed to their ability to secrete various trophic mediators able to stimulate endogenous glomerular repair mechanisms. Injected AFSC that lodged within glomerular capillaries modulated VEGF/sVEGFR1 levels, preventing further endothelial damage, possibly by activating endogenous repair mechanisms. We confirmed that AFSC release EVs that express various surface markers, including VEGFR1 and VEGFR2, and can modulate VEGF/VEGFRs signaling in damaged GEC by decreasing the bio-availability of excess VEGF. Our data confirm the ability of AFSC to ameliorate renal damage and establish that their secreted EVs could target a specific signaling pathway re-establishing GEC function, representing a potentially new glomerulus-specific targeted intervention

Methods

Results

Conclusion