Blood sampling and plasma preparation for miRNA quantification
haemolysis
BLOOD
To minimize pre-analytical variables that might influence the miRNA expression profile, collection of blood and the preparation of plasma was conducted with a minimal risk of blood cell contamination and haemolysis. Before and after each intervention, fingertip capillary blood samples (≥ 200 μL) were collected in microvettes (system for capillary blood collection) containing Ethylenediaminetetraacetic acid (EDTA). Blood samples were centrifuged for 10 min at 3000 rpm and 4 °C. After the first centrifugation step, the upper plasma phase was transferred to a new tube without disturbing the intermediate buffy coat layer. The plasma samples were centrifuged a second time for 10 min at 15,000 rpm and 4 °C. The cleared supernatant was carefully transferred to a new tube and frozen at − 80 °C.