Characteristics and utility of exosomes obtained from peripheral blood derived endothelial progenitor cells of PAH patients

Introduction: Pulmonary arterial hypertension (PAH) is a rare and fatal disease and reduced BMPR2 expression is causally linked to the disease. Endothelial progenitor cells (EPCs) contribute to angiogenesis and how these cells exert their effect is unknown, however exosomes (Exo) are thought to contribute. Methods: EPCs were isolated and cultured from both PAH and control patient’s peripheral blood (15mL). Following EPC expansion and characterisation, cells were washed and serum starved for 48h or cultures were transduced with either AdBMPR2myc, AdTrackLuc for 24h or untransduced. The supernatant was removed for differential centrifugation isolation of Exo’s. Following Exo characterisation surface marker expression was examined or treated Exos were used to treat PAH derived EPCs. Results: The expression of endothelial markers such as CD31, VEGFR2, CD146, Endoglin and VE-Cadherin were found to be significantly increased on the surface of control patient Exo’s when compared to EPCs. Interestingly, there is a significant reduction in expression of VEGFR2 on PAH derived Exos compared to control EPCs and Exos. Preliminary results show a significant 17-fold increase in BMPR2 expression of EPCs treated with Exos from EPCs with BMPR2 up-regulation compared to EPCs treated with untransduced Exos, and a significant 35-fold increase compared to the irrelevant virus treated Exos. Conclusions: EPC derived exosome possess endothelial surface markers, which may be altered in the presence of PAH. The impact of BMPR2 treatment on Exo properties and their ability to affect other cells is currently under investigation.