To study the expression characteristics of microRNA (miRNA) in liver and serum of rat models from donation after cardiac death (DCD).

Thirty SD rats were divided into DCD group and control group with 15 rats in each group by random number table method. After anesthesia by intraperitoneal injection of 4% chloral hydrate, diaphragmatic muscle was cut through abdominal midline incision to induce hypotension and hypoxia in rats, and then cardiac arrest was induced to construct DCD rat model. The anesthesia and operation methods in the control group were the same as those in the DCD group, without cutting the diaphragm. After the model was successfully constructed, blood was collected through inferior vena cava and liver tissue was obtained. miRNA microarray was used to detect the expression of miRNA in liver and serum. Random number table method was used to select some differentially expressed miRNAs in the liver tissue between DCD group and control group, and then were validated by real-time quantitative PCR (qT-PCR). The differentially expressed miRNAs which were verified by qRT-PCR, and some miRNAs with the most significant differentially expressed in liver and serum between the DCD group and the control group were selected, and their potential target genes were predicted and analyzed by miRDB database. Group t test or one-way ANOVA was used for comparison of measurement data of normal distribution between groups. P<0.05 was considered statistically significant.

The serum levels of ALT, AST, lactic dehydrogenase in DCD group were (76±12) U/L, (286±56) U/L, (1 658±126) U/L, all higher than those in control group [(44±11) U/L, (124±48) U/L, (2 539±122) U/L] (t=4.622, 16.916 and 16.315, all P<0.05). The expression of 38 miRNAs in the liver tissues of the DCD group were higher than that of the control group (all Fold Change>2, all P<0.05); 90 miRNAs were significantly down-regulated (all Fold Change <0.5, all P<0.05). The serum levels of 10 miRNAs of the DCD group were higher than that of the control group (all Fold Change>2, all P<0.05); 11 miRNAs were significantly down-regulated (all Fold Change <0.5, all P<0.05). The miR-100-5p, miR-540-3p and miR-10b-5p were up-regulated synchronically in liver and serum (all Fold Change >2, all P<0.05). The simultaneous expression of miR-1843a-5p and miR-342-5p was down-regulated (all Fold Change <0.5, all P<0.05). The results of qRT-PCR showed that the relative expressions of miR-183-3p, miR-10b-5p, miR-487b-5p, miR-100-5p, miR-503-5p, miRr-540-3p and miRr-219a-2-3p in liver tissues in DCD group were all up-regulated and there were statistically significant differences (t=2.808, 6.860, 10.106, 20.594, 3.697, 10.433 and 5.828, all P<0.05). The relative expressions of miR-3559-3p, miR-150-5p, miR-223-3p, miR-340-3p, miR-342-5p, miR-664-2-5, miR-219b and miR-224-3p were all down-regulated and there were statistically significant differences (t=-2.726, -3.318, -5.257, -4.845, -4.300, -5.082, -4.546 and -3.481, all P<0.05). The analysis of predict target genes of miRNAs showed that these miRNAs targeted a series of genes related to important biological processes related to DCD induced liver injury.

Specific expression profiles of miRNAs were found in liver and serum of DCD rats. These disregulated miRNAs could serve as potential non-invasive biomarkers for the assessment of DCD liver injury.