Blood collection, microvesicle isolation and RNA extraction. Peripheral
blood (7ml) was collected in tubes containing EDTA, and the tubes
were centrifuged at 400 g for 15min to separate the plasma fraction
from the blood cells. Aliquots of cell-free plasma were stored
at – 80 °C. Thawed samples were centrifuged three times at increasing
speeds (1000 g, 2000 g, 3000 g) for 15min at 4 °C to remove cell
debris and aggregates. Supernatants were ultracentrifuged at
110 000 g for 2 h at 4 °C. Enriched miRNAs were isolated with
the miRNeasy purification kit (Qiagen Hilden, Germany) following
the manufacturer’s instructions.