Study of transcriptional content in exosomes derived from untreated and growth factor-treated cultured cardiomyocytes (HL-1). Mus musculus

Introduction: Exosomes are nano-sized extracellular vesicles, released from various cells, which can stimulate or repress responses in target cells. We have recently shown that cultured cardiomyocytes release exosomes and that they, in turn, are involved in facilitating events in target cells by alteration of gene expression. We investigated whether external stimuli of the cardiomyocyte might influence the released exosome characteristics. Material and Methods: Exosomes were isolated from media collected from cultured cardiomyocyte (HL-1) cells with or without growth factor treatment (TGF-beta2 and PDGF-BB), with a series of differential centrifugations. The exosomes were characterized with dynamic light scattering (DLS) and Western blot and analysed with Illumina whole genome microarray gene expression. Results: An average size of 50-80 nm in diameter with no difference between treatment groups was found. Analysis of the mRNA content revealed 623 transcripts in the control group, 691 in the TGF-beta2-treated group and 362 in the PDGF-BB-treated group. 235 transcripts were common for all three groups. Conclusion: We conclude that there is a difference in mRNA content between exosomes derived from cultured cardiomyocytes stimulated with growth factors. We also conclude that all exosomes contain a basic package consisting of ribosomal transcripts and mRNAs coding for proteins with functions within the energy supply system. Overall design: To study if the transcriptional content in exosomes derived from untreated and growth factor-treated cultured cardiomyocytes (HL-1) differ, and if so, can this difference be explained, 4 control (untreated) exosome samples, 4 TFG-beta2-treated cardiomyocyte-derived exosome samples and 4 PDGF-BB-treated cardiomyocyte-derived exosomes were studied.