To investigate the effect of preservation time on the quality of miRNA markers for colorectal cancer in non-hemolytic and hemolytic states.

Colorectal cancer plasma samples stored for different time under -80℃ from 2014 to 2021 in the Biobank of Clinical Resources of the Third Affiliated Hospital, Sun Yat-sen University were randomly selected, the degree of plasma hemolysis was assessed by spectrophotometer and divided into hemolytic group and non-hemolytic group. After miRNA extraction, the abundance of miR-92a-3p and miR-378a-5p for colorectal cancer was analyzed by quantitative real-time PCR and compared.

Under the low temperature storage environment of -80℃, there was no significant change in the abundance of miR-92a-3p and miR-378a-5p in the plasma of the non-hemolytic group preserved for 8 years and the hemolytic group preserved for 3 years. After 1 and 3 years of storage, the abundance of miR-92a-3p in plasma of hemolytic group was significantly higher than that of non-hemolytic group (both P<0.01), while there were no significant differences in the abundance of miR-378a-5p between the two groups (P=0.931, 0.339).

The initial hemolytic state of plasma may affect the abundance of circulating miRNA, but the preservation time under the low temperature does not affect the abundance of miRNA in plasma samples, thus can better maintain the stability for subsequent studies.