Distinct degenerative phenotype of articular cartilage from knees with meniscus tear compared to knees with osteoarthritis

This study suggests that APM and TKA cartilage express distinct sets of OA transcripts. The gene profile in cartilage from TKA knees represents an end-stage OA whereas in APM knees it is clearly earlier in the degenerative process.

To compare the transcriptome of articular cartilage from knees with meniscus tears to knees with end-stage osteoarthritis (OA). Design: Articular cartilage was collected from the non-weight bearing medial intercondylar notch of knees undergoing arthroscopic partial meniscectomy (APM; N = 10, 49.7 ± 10.8 years, 50% females) for isolated medial meniscus tears and knees undergoing total knee arthroplasty (TKA; N = 10, 66.0 ± 7.6 years, 70% females) due to end-stage OA. Ribonucleic acid (RNA) preparation was subjected to SurePrint G3 human 8 × 60K RNA microarrays to probe differentially expressed transcripts followed by computational exploration of underlying biological processes. Real-time polymerase chain reaction amplification was performed on selected transcripts to validate microarray data.

We observed that 81 transcripts were significantly differentially expressed (45 elevated, 36 repressed) between APM and TKA samples (≥ 2 fold) at a false discovery rate of ≤ 0.05. Among these, CFD, CSN1S1, TSPAN11, CSF1R and CD14 were elevated in the TKA group, while CHI3L2, HILPDA, COL3A1, COL27A1 and FGF2 were highly expressed in APM group. A few long intergenic non-coding RNAs (lincRNAs), small nuclear RNAs (snoRNAs) and antisense RNAs were also differentially expressed between the two groups. Transcripts up-regulated in TKA cartilage were enriched for protein localization and activation, chemical stimulus, immune response, and toll-like receptor signaling pathway. Transcripts up-regulated in APM cartilage were enriched for mesenchymal cell apoptosis, epithelial morphogenesis, canonical glycolysis, extracellular matrix organization, cartilage development, and glucose catabolic process. Conclusions: This study suggests that APM and TKA cartilage express distinct sets of OA transcripts. The gene profile in cartilage from TKA knees represents an end-stage OA whereas in APM knees it is clearly earlier in the degenerative process.