Integrative analysis of miRNA in cartilage-derived extracellular vesicles and single-cell RNA-seq profiles in knee osteoarthritis.

Extracellular vesicular miRNAs (EV-miRNAs) play essential roles as intercellular communication molecules in knee Osteoarthritis (OA). We isolated cartilage-derived extracellular vesicles (EVs), to perform miRNA sequencing, which revealed EV-miRNA profiles and identified differentially expressed miRNAs (DE-miRNAs) between cartilage injury and cartilage non-injury groups. The target genes of known and novel DE-miRNAs were predicted with multiMiR package in 14 miRNA-target interaction databases. Meanwhile, single-cell RNA sequencing (scRNA-seq) was performed to identify chondrocyte clusters and their gene signatures in knee OA. Then we performed comparative analysis between target genes of the cartilage-derived EV-DE-miRNAs target genes and cluster-specific maker genes of characteristic chondrocyte clusters. Finally, the functional analysis of the cartilage-derived EVs DE-miRNA target genes and cluster-specific marker genes of each cell population were performed. The EV-miRNA profile analysis identified 13 DE-miRNAs and 7638 target genes. ScRNA-seq labelled seven clusters by cell type according to the expression of multiple characteristic markers. The results identified 735, 184, 303 and 879 common genes between EV-DE-miRNA target genes and cluster-specific marker genes in regulatory chondrocytes (RegCs), fibrocartilage chondrocytes (FC), prehypertrophic chondrocytes (PreHTCs) and mitochondrial chondrocytes (MTC), respectively. We firstly integrated the association between the cartilage-derived EV-DE-miRNA target genes and distinguished cluster-specific marker genes of each chondrocyte clusters. KEGG pathway analysis further identified that the DE-miRNAs target genes were significantly enriched in MAPK signaling pathway, Focal adhesion and FoxO signaling pathway. Our results provided some new insights into cartilage injury and knee OA pathogenesis which could improve the new diagnosis and treatment methods for OA.