Signature of microRNA expression during osteogenic differentiation of bone marrow MSCs reveals a putative role of miR-335-5p in osteoarthritis.

BACKGROUND: The aim of this study was to evaluate, the existence of a signature of differentially expressed microRNAs (miRNAs) during osteogenic differentiation of bone marrow MSCs from OA and healthy donors and to describe their possible implication in joint regeneration through modulation of molecular mechanisms involved in homeostatic control in OA pathophysiology. METHODS: Following phenotypic assessment of BM-MSCs obtained from OA diagnosed patients (n = 10) and non-OA (n = 10), total small RNA was isolated after osteogenic induction for 1, 10 and 21 days, miRNA profiles were generated using a commercial expression array of 754 well-characterized miRNAs. MiRNAs, with consistent differential expression were selected for further validation by quantitative reverse-transcription polymerase chain reaction (qRT-PCR) analysis. RESULTS: A total of 246 miRNAs were differentially expressed (fold change ≥ ± 2, P ≤0.05) between OA and non-OA BM-MSC samples; these miRNAs showed variable interactions depending on the cell and differentiation status. Two miRNAs, hsa-miR-210 and hsa-miR-335-5p out of 21 used for validation showed a significant downregulated expression during induced osteogenesis. In particular hsa-miR-335-5p, a critical regulator in bone homeostasis, was further studied. hsa-miR-335-5p downregulation in OA-MSCs, as well as their host coding gene, MEST, were also assessed. CONCLUSIONS: To our knowledge, this study represents the most comprehensive assessment to date of miRNA expression profiling in BM-MSCs from OA patients and their role during osteogenic differentiation. We describe the existence of a correlation between miR-335-5p expression and OA indicating the putative role of this miRNA in OA features. These findings, may contribute to our understanding of the molecular mechanisms involved in MSCs mediated homeostatic control in OA pathophysiology that could be applicable in future therapeutic approaches.

Selected reaction monitoring assays in mesenchymal stem cells from osteoarthritis patients.

Osteoarthritis (OA) is considered the most prevalent form of arthritis. The aim of this study was to verify potential protein OA biomarkers by applying Selected Reaction Monitoring (SRM) assays to protein extracts obtained from Bone Marrow-Mesenchymal Stem Cells (BM-MSCs) isolated from OA patients. BM aspirates were obtained from the femoral channel of OA patients at the time of surgery and from the femoral channel of hip fracture subjects without OA during hip joint replacement surgery for the treatment of subcapital fracture. SRM results verified the differential expression of several protein biomarkers in BM-MSCs from OA patients.

Alternative splicing and proteolytic rupture contribute to the generation of soluble IL-6 receptors (sIL-6R) in rheumatoid arthritis.

OBJECTIVE: To describe the relationship between the two mechanisms involved in sIL6R generation in rheumatoid arthritis (RA). METHOD: RA patients were selected from a group of subjects genotyped for the rs8192284 SNP, located at the proteolytic cleavage site of IL-6R. sIL6R and protease levels (ADAM17) were measured and the contribution of alternative splicing in the generation of sIL-6R was evaluated through qRT-PCR. RESULT: Increased sIL-6R plasma levels and expression of spliced isoform generating sIL-6R are genotype dependent. ADAM17 concentrations were independent of the genotype studied. CONCLUSION: Alternative splicing and proteolytic cleavage participate in sIL-6R generation in RA. The rs8192284 polymorphism determines the sIL-6R plasma level through differential proteolytic rupture controlled by ADAM17.

Combined influence of genetic and environmental factors in age of rheumatoid arthritis onset.

To study the combined effect of both genetic and environmental factors in the age of rheumatoid arthritis onset. Patients (n = 507). Shared epitope characterization was performed using Lifecodes HLA-SSO. Genotyping of protein tyrosine phosphatase non-receptor 22 (PTPN22) rs2476601 and signal transducers and activators of transcription 4 (STAT4) rs7574865 polymorphism was performed using fast real-time PCR System. Shared epitope, antibodies directed against cyclic citrulinated peptide (anti-CCP) antibodies and a higher level of education were associated with a younger age at disease onset (P = 0.033, P = 0.004 and P < 0.0001, respectively). Neither carriers of the minor allele of PTPN22 rs2476601 nor STAT4 rs7574 polymorphisms showed a significant association with a younger age at disease onset (P = 0.355, P = 0.065, respectively). We found an additive effect of the three genetic markers in the age at onset: subjects with three markers were associated with a disease onset 9.56, 8.61, and 6.41 years before than those with none, one, or two genetic markers (P = 0.004, P = 0.006 and P = 0.043, respectively). We also described the additive effect of shared epitope, anti-CCP antibodies, educational level, PTPN22, and STAT4 polymorphisms in age at onset. Patients with two, three, four, or five variables were associated with a significant younger age of disease onset (4.72 [0.05-9.38] years (P = 0.048), 9.56 [4.72-14.40] years (P < 0.0001), 12.74 [6.84-18.64] years (P < 0.0001), and 20.87 [10.40-37.17] years (P < 0.0001)). Risk factors for the development of rheumatoid arthritis are also associated, with an additive effect, with a younger age at disease onset.

Plasma soluble IL-6 receptor concentration in rheumatoid arthritis: associations with the rs8192284 IL6R polymorphism and with disease activity.

Soluble interleukin-6 receptor α subunit (sIL-6R) is primarily generated by shedding of the membrane-bound form. This process is influenced by the single nucleotide polymorphism rs8192284 (A > C) resulting in an aspartic acid to alanine substitution (D358A) at the proteolytic cleavage site. The aim of this study was to determine whether plasma levels of sIL6R are influenced by the rs8192284 polymorphism in patients with rheumatoid arthritis and to assess the association between plasma sIL-6R levels and disease activity as reflected by anti-CCP status. Thirty-nine patients were randomly selected from a cohort of patients with RA of Spanish descent. Plasma sIL-6R concentrations were measured using sandwich ELISA. Genotyping of the rs8192284 (A > C) polymorphism was done using a Fast Real-Time PCR System. DAS 28 scores were used to assess disease activity. Plasma sIL-6R levels were positively associated with the number of C alleles (AA: 35.27 (3.50) ng/ml, AC: 45.50 (4.58) ng/ml, CC: 52.55 (3.18) ng/ml, P = 0.0001). DAS28 and plasma sIL-6R levels were positively associated in the anti-CCP-positive subgroup (r (2) = 0.45, P = 0.0336) and negatively associated in the anti-CCP-negative subgroup (r (2) = -0.45, P = 0.0825). No association between anti-CCP status and sIL-6R level was found. Our findings show that the rs8192284 polymorphism is operative in patients with RA. The presence of anti-CCP antibodies determines the relationship between sIL-6R concentration and disease activity.

Adverse effects of xenogenic scaffolding in the context of a randomized double-blind placebo-controlled study for repairing full-thickness rotator cuff tears.

PURPOSE: The purpose of the study was to compare the safety and efficacy of autologous mesenchymal stem cells (MSCs) embedded in a xenogenic scaffold for repairing the supraspinatus tendon. METHODS: This was a randomized, double-blind and placebo-controlled trial evaluating patients with full-thickness rotator cuff tears (Eudra-CT, 2007-007630-19). Effectiveness was evaluated using the Constant score and a visual analogue pain scale (VAS). Constant score has four domains including pain (15 possible points), activities of daily living (20 possible points), mobility (40 possible points), and strength (25 possible points). Scores range from 0 points (most disability) to 100 points (least disability). The structural integrity of the repaired tendon was assessed by magnetic resonance imaging (MRI) according to Patte and Thomazeau classification criteria. The primary study end point was an improvement in the Constant score by 20 points at one year compared to initial assessment. RESULTS: The trial was stopped due to adverse effects observed in both groups. Only thirteen patients were included and analyzed. The Constant questionnaire showed a significant improvement in the MSC treatment group compared with the preoperative data (p = 0.0073). Secondary outcome measures were similar in both groups. CONCLUSIONS: Our study showed preliminary inconclusive clinical outcomes in the patients treated with MSCs. Adverse events revealed the need for further approaches using scaffolds of a different nature or perhaps no scaffolds, in the context of small joints. TRIAL REGISTRATION: Eudra-CT, 2007-007630-19 . Registered on 30 January 2008. LEVEL OF EVIDENCE: A Level 1 of evidence treatment study.

Characteristics of GLP-1 and exendins action upon glucose transport and metabolism in type 2 diabetic rat skeletal muscle.

Exendin-4, a peptide 53% structurally homologous with glucagon-like peptide 1 (GLP-1), is insulinotropic and has an antidiabetic effect even more prolonged than that of GLP-1. Exendin-9 is an antagonist of GLP-1 receptor and action in several cell systems, but shows GLP-1- and exendin-4-agonistic characteristics in human muscle cells and tissue. The action of GLP-1 upon glucose transport and metabolism in muscle is mediated by specific receptors. In this study we investigated the effect of both exendin-4 and -9, relative to that of GLP-1, upon glucose transport and metabolism in the skeletal muscle from a streptozotocin-induced type 2 diabetic rat model, compared to normal. In normal rats, exendin-4, like GLP-1 and insulin, enhanced glucose uptake. This effect, which is mediated to a certain extent by some kinases (PI3K/ PKB, p70s6k and MAPKs), may be caused by the peptide acting, at least in part, through the muscle GLP-1 receptors. Exendin-9 also stimulated the same kinases, except for PKB, but failed to modify basal glucose uptake. Type 2 diabetic rats showed lower than normal basal muscle glucose transport and oxidation value, and higher glycogen synthase alpha activity and pyruvate release; however, no modification of glucose uptake by GLP-1 or exendin-4 was detected, at variance with insulin, and basal activity of PI3K/PKB was lower than normal, while that of p70s6k and MAPKs was higher. GLP-1 failed to affect the activity of any of the kinases, while exendin-4 increased the activity of PI3K, p70s6k and MAPKs, but not PKB, suggesting that this enzyme plays a major role in exendin-4 effect upon glucose transport in muscle.

GLP-1 signalling and effects on glucose metabolism in myocytes from type 2 diabetic patients.

Changes in the activity of glycogen synthase a and related kinases (phosphatidylinositol-3-kinase, protein kinase B, p44/42 MAP kinases and p70s6 kinase) evoked by GLP-1 in human myocytes from normal subjects were recently implied in the effect of this hormone upon D-glucose transport and glycogen synthesis in the same cells. The major aims of the present study were i) to investigate the possible extension of this knowledge to myocytes obtained from type 2 diabetic patients, ii) to compare in these patients the response to GLP-1, insulin or the structurally related GLP-1 peptides, exendin (1-39)amide and exendin(9-39)amide, and iii) to explore possible differences in the responsiveness to these agents between normal and diabetic subjects. Apart from the much higher basal PI3K activity and impaired response to insulin of p44/42 MAP kinases in the diabetic patients, the changes in enzyme activity caused by either hormone or peptide, although not identical, were essentially comparable. Nevertheless, significant differences in glucose transport and metabolism parameters were observed in the diabetic patients vs. normal subjects: in the diabetic patients, basal 2-deoxy-glucose uptake and glycogen synthase a activity were lower, accompanied by a similar increasing effect of GLP-1 or insulin; yet, the basal value for glycogen synthesis was higher, coinciding with a lesser relative increment in response to GLP-1 or insulin.

Altered Expression of Wnt Signaling Pathway Components in Osteogenesis of Mesenchymal Stem Cells in Osteoarthritis Patients.

INTRODUCTION: Osteoarthritis (OA) is characterized by altered homeostasis of joint cartilage and bone, whose functional properties rely on chondrocytes and osteoblasts, belonging to mesenchymal stem cells (MSCs). WNT signaling acts as a hub integrating and crosstalking with other signaling pathways leading to the regulation of MSC functions. The aim of this study was to evaluate the existence of a differential signaling between Healthy and OA-MSCs during osteogenesis. METHODS: MSCs of seven OA patients and six healthy controls were isolated, characterised and expanded. During in vitro osteogenesis, cells were recovered at days 1, 10 and 21. RNA and protein content was obtained. Expression of WNT pathway genes was evaluated using RT-qPCR. Functional studies were also performed to study the MSC osteogenic commitment and functional and post-traslational status of ß-catenin and several receptor tyrosine kinases. RESULTS: Several genes were downregulated in OA-MSCs during osteogenesis in vitro. These included soluble Wnts, inhibitors, receptors, co-receptors, several kinases and transcription factors. Basal levels of ß-catenin were higher in OA-MSCs, but calcium deposition and expression of osteogenic genes was similar between Healthy and OA-MSCs. Interestingly an increased phosphorylation of p44/42 MAPK (ERK1/2) signaling node was present in OA-MSCs. CONCLUSION: Our results point to the existence in OA-MSCs of alterations in expression of Wnt pathway components during in vitro osteogenesis that are partially compensated by post-translational mechanisms modulating the function of other pathways. We also point the relevance of other signaling pathways in OA pathophysiology suggesting their role in the maintenance of joint homeostasis through modulation of MSC osteogenic potential.

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.

Influence of IL6R rs8192284 polymorphism status in disease activity in rheumatoid arthritis.

OBJECTIVE: To analyze the influence of IL6R rs8192284 polymorphism on the disease activity of rheumatoid arthritis (RA). METHODS: Patients with RA (n = 281) were followed for a median of 4.2 years. A total of 1143 disease activity measurements using the 28-joint count Disease Activity Score (DAS28) were performed. A mixed-effect model was used to analyze the measurements. RESULTS: A statistically significant interaction was observed between IL6R rs8192284 polymorphism and the presence of anticyclic citrullinated peptide (anti-CCP) antibodies (p = 0.008). An inverse relationship between the polymorphism and DAS28 was observed depending on anti-CCP status. CONCLUSION: The anti-CCP status in patients with RA determines the association between the IL6R rs8192284 polymorphism and disease activity.