MicroRNA profiling of filtering and non-filtering regions of human trabecular meshwork: changes with ageing and in glaucoma.

BACKGROUND: Adult stem cells for trabecular meshwork (TMSCs) present in the non-filtering region (NF) decreased with ageing and were significantly reduced in primary open angle glaucoma (POAG). This study aimed to profile the trabecular meshwork (TM) region specific miRNAs and to analyse their expression patterns in aged and glaucomatous donor tissues. METHODS: Using the nanoString nCounter platform, miRNA profiling of the filtering (F) and NF regions of human donor TM was carried out. Differentially expressed miRNAs were validated in age-stratified donor tissues (0-30, 30-60, > 60 years) and FFPE sections from POAG donors by quantitative real-time PCR (qRT-PCR). miRTarBase was used to identify the targets of validated miRNAs, and Shiny GO 0.82 was used to perform functional enrichment analysis. RESULTS: Thirty-one miRNAs showed significant up-regulation, and three exhibited down-regulation in the NF region compared to the F region (fold change ≥ ± 1.2). The increased expression of miR-24-3p, miR-107, miR-34a-5p, miR-184, and decreased expression of miR-376a-3p, miR-145-5p and miR-22-3p in the NF region was validated by qRT-PCR, highlighting their probable role in stem cell regulation. Bioinformatic analysis also suggested their involvement in stem cell-related pathways, including Wnt, HIF, PI3K-AKT, and MAPK signalling. An age-related decline in miR-107, miR-184, and miR-34a-5p expression was observed in the NF region. Interestingly, miR-145-5p, miR-22-3p and miR-376a-3p showed up-regulation in TM of glaucomatous tissues. CONCLUSION: This study identified differentially expressed miRNAs in the NF region of the human TM. The up-regulated miRNAs exhibited an age-associated decline and were also reduced in the young glaucomatous donor. Further miRNA transfection studies are essential to elucidate their specific roles in TMSC regulation.