The Impact of Osteoarthritis on the Biology of the Meniscus:

Objectives: To identify novel gene transcripts and biological processes in meniscus from patients with and without osteoarthritis (OA). Methods: We used microarrays to identify gene transcripts differentially expressed in meniscus tissues obtained from OA and non-OA patients (N=12 each). Real-time PCR was performed on selected gene transcripts. Biological processes and gene networking was examined computationally. Transcriptome signatures from OA and non-OA meniscus were mapped with 37 previously published gene transcripts differentially expressed between healthy and OA cartilage to evaluate how meniscus gene expression relates to cartilage with this disease. Results: We identified 168 gene transcripts that were significantly differentially expressed between OA (75 elevated, 93 repressed) and non-OA samples (≥1.5-fold). Among these, CSN1S1, COL10A1, WIF1, SPARCL1 and DEFA3 were the most prominent gene transcript elevated in OA meniscus and POSTN, VEGFA, CEMIP, COL6A3 and SOX11 were repressed in OA meniscus. Gene transcripts elevated in OA meniscus represented response to external stimuli, cell migration and localization while those repressed in OA meniscus represented histone deacetylase activity and skeletal development. Numerous long lncRNAs were differentially expressed between the two samples. When segregated by OA-associated gene transcripts, we observed three distinct clustering patterns of OA and non-OA meniscus. Conclusions: These data provide novel evidence for a role of epigenetically regulated histone deacetylation in meniscus tears as well as expression of lncRNAs. Patient clustering based on OA-associated gene transcripts confirmed that the meniscus in OA knees exhibited OA phenotype while injured meniscus demonstrated some signs towards OA. We used Agilent microarrays to identify gene transcripts differentially expressed in meniscus tissues obtained from 12 patients with osteoarthritis and from 12 patients without osteoarthritis (arthroscopic partial meniscectomy.