Plasma-derived exosomal miR-34a-5p: a potential diagnostic biomarker for total colonic aganglionosis.

Background: Hirschsprung's disease (HSCR) is marked by the absence of enteric neurons in the distal colon, with total colonic aganglionosis (TCA) representing a rare and severe variant of the condition. The objective of the study is to examine critical microRNAs and their corresponding genes in plasma-derived exosomes from patients with HSCR, focusing on their potential as biomarkers for TCA. Methods: A total of nine individuals with HSCR, including three cases of TCA, were enrolled in the study between September 2019 and July 2022. Additionally, 10 healthy children were recruited as controls. Plasma-derived exosomes were isolated using ultracentrifugation, followed by total RNA extraction. The microRNAs within these exosomes were analyzed using small RNA next-generation sequencing, and differentially expressed microRNAs were identified through differential expression analysis. Functional insights into these differentially expressed microRNAs were examined utilizing Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and interaction network analysis. Results: From microRNA sequencing, 62 microRNAs exhibited differential expression in plasma-derived exosomes, with 31 upregulated and 31 downregulated. The upregulated microRNAs were associated with 652 target gene pairs, while the downregulated microRNAs corresponded to 234 target gene pairs. Notably, four differentially expressed microRNAs (miR-106b-5p, miR-205-5p, miR-375-3p, and miR-34a-5p) displayed distinct expression patterns between other types of HSCR and TCA. Among these, miR-34a-5p exhibited significantly higher expression in the TCA group, as confirmed by quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis. Conclusions: The findings of this study underscore the significant potential of the microRNA miR-34a-5p and its associated gene as promising candidates for use as plasma biomarkers in the diagnosis of TCA.