Abstract
Purpose: :
Microvesicles are membrane-derived vesicles released into the extracellular space by activated or apoptotic eukaryotic cells. Microvesicles have been shown to transfer proteins and RNA from one cell to another and are thought to mediate intercellular communication. We investigated the ability of microvesicles derived from embryonic stem cells (ESMVs) to transfer miRNAs to other cells.
Methods: :
ESMVs were collected from embryonic stem cells (ESCs) by differential ultra-centrifugation and incubated with growth-arrested mouse embryonic fibroblasts (MEFs) for 1, 12, 36, and 54 hours to study miRNA transfer from ESMVs to MEFs. MEFs without exposure to ESMVs were used to determine the baseline expression level of MEF miRNAs. To collect cells while removing unattached ESMVs, MEFs were washed with PBS twice prior to and twice after enzymatic dissociation from plates. MEF total RNA was isolated and qRT-PCR was used to quantify ESC-specific miRNAs (miR-290, miR-291-3p, miR-292-3p, miR-294, and miR-295), the ubiquitously expressed miR-16, and a small nuclear RNA, RNU6B. Transfer of miRNAs was estimated as the difference between the miRNA content of MEFs and that of the MEFs incubated with ESMVs.
Results: :
The abundance of all five ESC-specific miRNAs tested increased in MEFs as early as 1 hour after incubation, suggesting transfer. Transfer seemed to peak at approximately 36 hours and at 54 hours the levels of the transferred miRNAs had not returned to baseline. However, this was not observed with miR-16 and RNU6B, the levels of which remained near baseline at all time points tested.
Conclusions: :
ESMVs are capable of transferring a subset of ESC-specific miRNAs to MEFs. Levels of miR-16 and RNU6B, both already present in MEFs, did not increase after incubation with ESMVs. Our results suggest that the transfer of miRNAs by ESMVs may represent a novel role for miRNAs in the translational regulation of neighboring cells. Furthermore, ESMVs engineered to transfer specific miRNAs that target mutated photoreceptor mRNAs may be used to treat retinal degenerations.
Keywords: gene transfer/gene therapy • cell-cell communication • gene/expression