Stem Cell Microvesicles Transfer Cystinosin to Human Cystinotic Cells and Reduce Cystine Accumulation In Vitro

Diana M Iglesias,Jing Zhao,Leelee Chu,Martine Besouw,Lambertus Van Den Heuvel,Francesco Emma,Jaan Toelen,Elena Levtchenko,Yoon Kow Young,Francesco Bellomo,Paul Goodyer,Reyhan El-Kares,Anna Taranta,Nicoletta Eliopoulos

doi:10.1371/journal.pone.0042840

Abstract

Cystinosis is a rare disease caused by homozygous mutations of the CTNS gene, encoding a cystine efflux channel in the lysosomal membrane. In Ctns knockout mice, the pathologic intralysosomal accumulation of cystine that drives progressive organ damage can be reversed by infusion of wildtype bone marrow-derived stem cells, but the mechanism involved is unclear since the exogeneous stem cells are rarely integrated into renal tubules. Here we show that human mesenchymal stem cells, from amniotic fluid or bone marrow, reduce pathologic cystine accumulation in co-cultured CTNS mutant fibroblasts or proximal tubular cells from cystinosis patients. This paracrine effect is associated with release into the culture medium of stem cell microvesicles (100–400 nm diameter) containing wildtype cystinosin protein and CTNS mRNA. Isolated stem cell microvesicles reduce target cell cystine accumulation in a dose-dependent, Annexin V-sensitive manner. Microvesicles from stem cells expressing CTNSRed transfer tagged CTNS protein to the lysosome/endosome compartment of cystinotic fibroblasts. Our observations suggest that exogenous stem cells may reprogram the biology of mutant tissues by direct microvesicle transfer of membrane-associated wildtype molecules.

Highlights

Cystinosis is a rare disorder caused by homozygous mutations of the CTNS gene on the short arm of chromosome 17q, encoding a ubiquitous cystine-selective transport channel in the lysosomal membrane [1]
Long regarded as inactive cellular debris, microvesicles shed from the surface of viable cells are increasingly recognized as important vehicles for the transfer of complex biologic information between neighboring cells
We show that mesenchymal stem cells shed microvesicles containing wildtype cystinosin protein and mRNA

Summary

Introduction

Cystinosis is a rare disorder caused by homozygous mutations of the CTNS gene on the short arm of chromosome 17q, encoding a ubiquitous cystine-selective transport channel in the lysosomal membrane [1]. Loss of this transporter prevents cystine efflux from the lysosome, causing massive accumulation of intralysosomal cystine in tissues throughout the body [2,3] and eventual apoptotic cell death [4].

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Results

Conclusion