Large-scale gene expression in bone marrow mesenchymal stem cells: a putative role for COL10A1 in osteoarthritis.

OBJECTIVES: To elucidate disease-specific molecular changes occurring in osteoarthritis (OA) by analysing the differential gene expression profiles of bone marrow mesenchymal stem cells (BM-MSCs) from patients with OA compared with those without OA. METHODS: Expression profiles of BM-MSCs from eight paired patients with OA and patients with hip fracture without signs of OA were compared by DNA microarray expression analysis and significant differences were evaluated by computational Gene Set Enrichment Analysis. To validate the involvement of COL10A1 as part of the most downregulated gene set in OA, three tagging single nucleotide polymorphisms were genotyped in 191 patients with OA and 283 controls. COL10A1 expression was also assessed by quantitative RT-PCR in additional subjects. RESULTS: Expression levels in 9% (1967) of the overall transcripts were significantly different (p<0.05) between MSCs from patients with OA and controls (532 genes reached twofold differences: 240 were upregulated and 292 were downregulated). Cell development and differentiation were the functional categories accounting for most genes with altered expression. Interestingly, several genes related to the Wnt/-catenin pathway and collagen genes were downregulated in MSCs from patients with OA. The collagen gene set was clearly downregulated in OA. Furthermore, the expression of COL10A1 was significantly reduced in patients with OA. A genetic association between the COL10A1 rs11965969 polymorphism and OA was also found. CONCLUSION: COL10A1 downregulation seems to have a role in the establishment of a defective and/or unstable subchondral cartilage matrix in OA disease. It is proposed that OA may be linked to the intrinsic defective regenerative potential of BM-MSCs resulting from its reduced expression of fate commitment-related genes.

The ubiquitin-proteasome pathway and viral infections in articular cartilage of patients with osteoarthritis.

Many viruses can evolve different strategies to exploit the ubiquitin-proteasome pathway (UPP) for their own benefit. Some data have recently established connections between UPP and osteoarthritis (OA). The aim of this study was to determine the possible involvement of viral infections linked with the UPP in the physiopathology of OA. Samples of human cartilage were obtained from 12 patients with clinical and radiological features of OA and from 12 normal controls. DNA was extracted from cultured chondrocytes from these patients, and quantitative real-time PCR was performed to analyse the DNA/RNA prevalence and viral loads of HSV, EBV, HCMV, enterovirus, and HTLV-1. The prevalence of total viral DNA/RNA among patients with OA was 16.7% (mean viral load of 7.86 copies/mug DNA), EBV being responsible for the two positive samples, while the prevalence in controls was 0%. We did not detect any positive samples for HSV, CMV, enterovirus, and HTLV-1 among patients with OA and controls. This first approach to the study of the prevalence of viruses linked to the UPP in articular cartilage of end-stage OA patients provides evidences supporting the risk of EBV transmission or reactivation in a subset of patients with disorders requiring tissue regeneration.

Efficacy of supraspinatus tendon repair using mesenchymal stem cells along with a collagen I scaffold.

OBJECTIVES: Our main objective was to biologically improve rotator cuff healing in an elderly rat model using mesenchymal stem cells (MSCs) in combination with a collagen membrane and compared against other current techniques. METHODS: A chronic rotator cuff tear injury model was developed by unilaterally detaching the supraspinatus (SP) tendons of Sprague-Dawley rats. At 1 month postinjury, the tears were repaired using one of the following techniques: (a) classical surgery using sutures (n = 12), (b) type I collagen membranes (n = 15), and (c) type I collagen membranes + 1 × 106 allogeneic MSCs (n = 14). Lesion restoration was evaluated at 1, 2, and 3 months postinjury based on biomechanical criteria. Continuous variables were described using mean and standard deviation (SD). To analyse the effect of the different surgical treatments in the repaired tendons' biomechanical capabilities (maximum load, stiffness, and deformity), a two-way ANOVA model was used, introducing an interaction between such factor and time (1, 2, and 3 months postinjury). RESULTS: With regard to maximum load, we observed an almost significant interaction between treatment and time (F = 2.62, df = 4, p = 0.053). When we analysed how this biomechanical capability changed with time for each treatment, we observed that repair with OrthADAPT and MSCs was associated with a significant increase in maximum load (p = 0.04) between months 1 and 3. On the other hand, when we compared the different treatments among themselves at different time points, we observed that the repair with OrthADAPT and MSCs has associated with a significant higher maximum load, when compared with the use of suture, but only at 3 months (p = 0.014). With regard to stiffness and deformity, no significant interaction was observed (F = 1.68, df = 4, p = 0.18; F = 0.40, df = 4, p = 0.81; respectively). CONCLUSIONS: The implantation of MSCs along with a collagen I scaffold into surgically created tendon defects is safe and effective. MSCs improved the tendon's maximum load over time, indicating that MSCs could help facilitate the dynamic process of tendon repair.