ABSTRACT
Objective To explore the potential predictive value of plasma exosomal miR-422a in different time after ischaemic stroke (1, 2, 3, 4 day) .Methods Retrospective study.Forty patients diagnosed with ischaemic stroke ( IS ) and ten age and sex matched people who underwent a standard physical examination were recruited from the First Affiliated Hospital of Guangxi Medical University between May 2016 and December 2016.Plasma exosomes were extracted by use of related kit and the expression level of plasma exosomal miR-422a in both IS patients (1, 2, 3, 4 day) and healthy controls were examined via quantitative real-time polymerase chain reaction ( qRT-PCR ) .The areas under the curve ( AUC ) of the receiver operating characteristic curve were constructed to evaluate the diagnostic accuracy of the miR -422a in IS, and one-way analysis of variance followed by the Games-Howell post hoc test was used for difference analysis.Results The exosomes isolated from human plasma showed round or oval vesicles , the average particle size was 128.2 nm and with maximum peak distribution of 186.9 nm.Moreover , all of the isolated exosomes were positive for a marker , with the CD63-positive rate at 80.6％ and the CD81-positive rate at 91.7％.qRT-PCR confirmed that miR-422a was expressed in human plasma exosomes , and the expression levels of plasma exosomal miR-422a [median relative values, 1.221 (95％CI:0.640-1.802) for healthy group, 4.418 (95％CI:2.642-6.193) for group of 1 dayafter IS, 2.912 (95％CI:2.262-3.562) for 2 day, 2.744 (95％CI:2.000-3.487) for 3 day and 0.449 (95％CI:0.170-0.727) for 4 day] were significantly increased in the time after IS 1, 2, 3 day ( F=13.57, P<0.05, P<0.01, P<0.05, respectively;and the AUC values were 0.920, 0.945, 0.870, respectively ) .The expression of plasma exosomal miR-422a on the 4th day after IS were lower than those in other IS groups ( F=13.57,P<0.005, P<0.001, P<0.001, respectively), and no statistical significance was found between the expression of plasma exosomal miR-422a on the 4th day after IS than that in the control group [0.449 (95％CI:0.170-0.727)].Conclusion Plasma exosomal miR-422a showed high diagnostic value as blood-based biomarker for diagnosing IS in the early phase (1-3 d).