Characterization of mRNA and microRNA in human mast cell-derived exosomes and their transfer to other mast cells and blood CD34 progenitor cells

Abstract

Background: Exosomes are nanosized vesicles of endocytic origin that are released into the extracellular environment by many different cells. It has been shown that exosomes from various cellular origins contain a substantial amount of RNA (mainly mRNA and microRNA). More importantly, exosomes are capable of delivering their RNA content to target cells, which is a novel way of cell-to-cell communication. The aim of this study was to evaluate whether exosomal shuttle RNA could play a role in the communication between human mast cells and between human mast cells and human CD34⁺ progenitor cells. Methods: The mRNA and microRNA content of exosomes from a human mast cell line, HMC-1, was analysed by using microarray technology. Co-culture experiments followed by flow cytometry analysis and confocal microscopy as well as radioactive labeling experiments were performed to examine the uptake of these exosomes and the shuttle of the RNA to other mast cells and CD34⁺ progenitor cells. Results: In this study, we show that human mast cells release RNA-containing exosomes, with the capacity to shuttle RNA between cells. Interestingly, by using microRNA microarray analysis, 116 microRNAs could be identified in the exosomes and 134 microRNAs in the donor mast cells. Furthermore, DNA microarray experiments revealed the presence of approximately 1800 mRNAs in the exosomes, which represent 15% of the donor cell mRNA content. In addition, transfer experiments revealed that exosomes can shuttle RNA between human mast cells and to CD34⁺ hematopoietic progenitor cells. Conclusion: These findings suggest that exosomal shuttle RNA (esRNA) can play a role in the communication between cells, including mast cells and CD34⁺ progenitor cells, implying a role in cells maturation process.

To access the supplementary material to this article: Tables S1-S6, please see Supplementary files under Article Tools online.

• exosomes
• extracellular vesicles
• human mast cells
• RNA
• esRNA

Acknowledgements

We gratefully acknowledge Swegene Microarray Resource Centre at Lund University (Lund, Sweden) for help with the Affymetrix microarray processing and ATLAS Biolabs GmbH (www.atlas-biolabs.com) for analysis of the Affymetrix data and Exiqon Company for microRNA microarray processing. The human mast cell line HMC-1 was kindly provided by G. Nilsson (Uppsala University, Uppsala, Sweden) and J. Butterfield (Mayo Clinic). We thank B. R. Johansson, U. Nannmark and Y. Josefsson at The Electron Microscopy Unit, Institute of Biomedicine, University of Gothenburg (Gothenburg, Sweden) for help with the electron microscopy. The staff at Centre for Cellular Imaging at University of Gothenburg provided excellent support and suggestions for the use of the imaging equipment. We are also grateful to T. Nyström at the Cell and Molecular Biology Laboratory at the University of Gothenburg for providing laboratory resources for some of the experiments.

The current experiments were funded by the Swedish Research Council (K2008-57X-20676-01-3), the Swedish Heart and Lung foundation and the Swedish Asthma-Allergy Foundation. J.L. is funded by Herman Krefting's Foundation against Asthma/Allergy.