title: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Krefting Research Centre, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden ; Department of Biomaterials, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden ; BIOMATCELL VINN Excellence Center of Biomaterials and Cell Therapy, Gothenburg, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Ekström
authors.forename: Hadi
authors.initials: H
authors.lastname: Valadi
authors.forename: Margareta
authors.initials: M
authors.lastname: Sjöstrand
authors.forename: Carina
authors.initials: C
authors.lastname: Malmhäll
authors.forename: Apostolos
authors.initials: A
authors.lastname: Bossios
authors.forename: Maria
authors.initials: M
authors.lastname: Eldh
authors.forename: Jan
authors.initials: J
authors.lastname: Lötvall
keywords: RNA; esRNA; exosomes; extracellular vesicles; human mast cells