P-190 Poster of distinction

Microvesicles (MVs) derived from endothelial progenitor cells (EPCs) enhance neoangiogenesis of transplanted human pancreatic islets through microRNA (miRNA) transfer

D. Medica¹, V. Cantaluppi², F. Figliolini¹, S. Beltramo¹, M. De Lena¹, R, Romagnoli³, M. Salizzoni³, G.P. Segoloni², L. Biancone², G. Camussi^1
1 Research Center for Experimental Medicine (CeRMS), University of Turin , Turin, Italy; ² Nephrology, Dialysis and Renal Transplantation Unit, University of Turin , Turin, Italy; ³ Liver Transplantation Center, Turin, Italy

Objective:The efficacy of islet transplantation is limited by poor graft vascularization. Endothelial Progenitor Cells (EPCs) are pro-angiogenic progenitors able to release microvesicles (MVs), active particles involved in cell-to-cell communication through RNA transfer. The aims of this study were to evaluate: 1) the effects of EPC MVs in experimental islet transplantation; 2) the effects of MVs on isolated islet endothelial cells (IECs); 3) the role of MV-shuttled miRNAs.

Methods: MVs were obtained by ultracentrifugation of supernatants of EPC isolated from peripheral blood. The effect of MVs was evaluated in an experimental model of islet xenograft in SCID mice and in vitro in purified human islets ( insulin secretion, apoptosis) and in IECs ( proliferation, resistance to apoptosis and angiogenesis on Matrigel). By RT-PCR array, we analyzed MV-shuttled mRNAs/miRNAs and the modulation of angiogenic genes induced by MVs in IECs.

Results: MVs were internalized in endothelial and beta cells, favoring insulin secretion, survival and revascularization of transplanted islets. MVs induced IEC proliferation, migration, resistance to apoptosis and organization in vessel-like structures. These effects were almost completely abrogated when MVs were pre-treated with 1U/ml Rnase or using MVs released from EPCs engineered to knock-down Dicer, the intracellular enzyme essential for miRNA production. MVs were enriched of miRNAs and carried the pro-angiogenic miR-126 and miR-296 that play a key role in MV-induced angiogenesis. MV-stimulated IECs showed the up-regulation of mRNAs coding for factors involved in endothelial proliferation, differentiation and angiogenesis and the activation of the PI3K-Akt and eNOS signaling pathways.

Conclusions: EPC-derived MVs favor insulin secretion and activate an angiogenic program in transplanted islets through the transfer of mRNAs/miRNAs. MVs may sustain revascularization and beta-cell function after islet transplantation.

P-190 Poster of distinction

Microvesicles (MVs) derived from endothelial progenitor cells (EPCs) enhance neoangiogenesis of transplanted human pancreatic islets through microRNA (miRNA) transfer

D. Medica¹, V. Cantaluppi², F. Figliolini¹, S. Beltramo¹, M. De Lena¹, R, Romagnoli³, M. Salizzoni³, G.P. Segoloni², L. Biancone², G. Camussi^1
1 Research Center for Experimental Medicine (CeRMS), University of Turin , Turin, Italy; ² Nephrology, Dialysis and Renal Transplantation Unit, University of Turin , Turin, Italy; ³ Liver Transplantation Center, Turin, Italy

Objective:The efficacy of islet transplantation is limited by poor graft vascularization. Endothelial Progenitor Cells (EPCs) are pro-angiogenic progenitors able to release microvesicles (MVs), active particles involved in cell-to-cell communication through RNA transfer. The aims of this study were to evaluate: 1) the effects of EPC MVs in experimental islet transplantation; 2) the effects of MVs on isolated islet endothelial cells (IECs); 3) the role of MV-shuttled miRNAs.

Methods: MVs were obtained by ultracentrifugation of supernatants of EPC isolated from peripheral blood. The effect of MVs was evaluated in an experimental model of islet xenograft in SCID mice and in vitro in purified human islets ( insulin secretion, apoptosis) and in IECs ( proliferation, resistance to apoptosis and angiogenesis on Matrigel). By RT-PCR array, we analyzed MV-shuttled mRNAs/miRNAs and the modulation of angiogenic genes induced by MVs in IECs.

Results: MVs were internalized in endothelial and beta cells, favoring insulin secretion, survival and revascularization of transplanted islets. MVs induced IEC proliferation, migration, resistance to apoptosis and organization in vessel-like structures. These effects were almost completely abrogated when MVs were pre-treated with 1U/ml Rnase or using MVs released from EPCs engineered to knock-down Dicer, the intracellular enzyme essential for miRNA production. MVs were enriched of miRNAs and carried the pro-angiogenic miR-126 and miR-296 that play a key role in MV-induced angiogenesis. MV-stimulated IECs showed the up-regulation of mRNAs coding for factors involved in endothelial proliferation, differentiation and angiogenesis and the activation of the PI3K-Akt and eNOS signaling pathways.

Conclusions: EPC-derived MVs favor insulin secretion and activate an angiogenic program in transplanted islets through the transfer of mRNAs/miRNAs. MVs may sustain revascularization and beta-cell function after islet transplantation.