This study focused on analyzing the differential expression profiles of microRNAs in the plasma of a rat model with post-traumatic osteoarthritis (PTOA) and aimed to elucidate the role of microRNAs in the pathogenesis and progression of PTOA through bioinformatics analysis.

Blood samples were collected from nine two-month-old female Sprague-Dawley rats, and microRNAs (miRNAs) were sequenced. The rats were divided into three groups: a normal control group (Group K: no intervention), a mild PTOA group induced by surgery (Group H: modified Hulth model at three weeks post-surgery), and a severe PTOA group induced by surgery (Group J: modified Hulth model at five weeks post-surgery). Differential miRNA expression was identified and validated using quantitative real-time polymerase chain reaction (qPCR). Bioinformatics analysis was performed to predict target genes and analyze associated pathways. A human knee osteoarthritis-like chondrocyte model was established by stimulating chondrocytes with recombinant human interleukin-1β (IL-1β). Reverse transcription PCR (RT-PCR) was used to verify whether the differentially expressed miRNAs were also differentially expressed in human knee chondrocytes and human knee osteoarthritis-like chondrocytes.

Differential expression was observed between Group H and Group K for miR-6315, miR-143-5p, miR-150-5p, and miR-301b-3p. Among these, miR-6315, miR-150-5p, and miR-301b-3p were upregulated, while miR-143-5p was down regulated. Between Group J and Group K, miR-6315 was significantly upregulated. However, between Group H and Group J, miR-511-3p and miR-301a-3p were upregulated and showed differential expression. Furthermore, in the comparison between Group K and Group H (early stage), miR-6315, miR-143-5p, miR-150-5p, and miR-301b-3p exhibited differential expression, suggesting their potential as biomarkers for joint injury in rat PTOA. In Group J, miR-6315 was also upregulated, consistent with the above findings. Thus, miR-511-3p and miR-301a-3p may serve as biomarkers to distinguish between mild and severe PTOA. Notably, miR-143-5p, miR-150-5p, and miR-301b-3p were differentially expressed in human knee osteoarthritis chondrocytes compared to normal human knee chondrocytes, with miR-150-5p and miR-301b-3p showing significant upregulation.

miR-6315, miR-143-5p, miR-150-5p, and miR-301b-3p may serve as biomarkers for joint injury in rat PTOA. Further investigation in human tissues is warranted to evaluate their potential applicability as biomarkers for PTOA in humans.