β1 Integrins Mediate Attachment of Mesenchymal Stem Cells to Cartilage Lesions

Mesenchymal stem cells (MSC) may have great potential for cell-based therapies of osteoarthritis. However, after injection in the joint, only few cells adhere to defective articular cartilage and contribute to cartilage regeneration. Little is known about the molecular mechanisms of MSC attachment to defective articular cartilage. Here, we developed an ex vivo attachment system, using rat osteochondral explants with artificially created full-thickness cartilage defects in combination with genetically labeled MSC isolated from bone marrow of human placental alkaline phosphatase transgenic rats. Binding of MSC to full-thickness cartilage lesions was improved by serum, but not hyaluronic acid, and was dependent on the presence of divalent cations. Additional in vitro tests showed that rat MSC attach, in a divalent cation-dependent manner, to collagen I, collagen II, and fibronectin, but not to collagen XXII or cartilage oligomeric matrix protein (COMP). RGD peptides partially blocked the adhesion of MSC to fibronectin in vitro and to cartilage lesions ex vivo. Furthermore, the attachment of MSC to collagen I and II in vitro and to cartilage lesions ex vivo was almost completely abolished in the presence of a β1 integrin blocking antibody. In conclusion, our data suggest that attachment of MSC to ex vivo full-thickness cartilage lesions is almost entirely β1 integrin-mediated, whereby both RGD- and collagen-binding integrins are involved. These findings suggest a key role of integrins during MSC attachment to defective cartilage and may pave the way for improved MSC-based therapies in the future

POEMS Syndrome: Real World Experience in Diagnosis and Systemic Therapy - 108 Patients Multicenter Analysis

POEMS syndrome, a rare plasma cell disorder, is challenging both in the diagnostic and therapeutic management. We present real word retrospective analysis of 108 cases analyzing clinical features and therapeutic modes. We compare our results with the available literature. This is the first description with such wide use of proteasome inhibitors in first line treatment. POEMS (Polyneuropathy, organomegaly, endocrinopathy, M-protein, skin changes) syndrome is a rare and challenging plasma cell disorder, both in the diagnostic and therapeutic management of the disease. Currently, the literature on POEMS is sparse with most evidence being case reports and small case studies. We present a retrospective real world experience of 108 patients with POEMS. We analyzed the clinical features and therapeutic interventions. Regarding clinical features, our findings demonstrated that skin lesions, thrombocythemia and polycythemia were present less frequently than reported previously. Regarding clinical interventions, this is one of the largest analyses of front line treatment in POEMS and the first one to include frequent utilization of proteasome inhibitors (37%). Bortezomib monotherapy was the most effective therapy achieving complete remission/very good partial remissions (CR/VGPR) in 69% of patients. Thirty percent of patients proceeded to planned autologous stem cell transplant (ASCT) as part of the front-line treatment resulting in statistically superior progression-free (PFS) and overall survival (OS) compared to non-ASCT treated patients (P= .003). In multivariate analysis, anemia, thrombocytopenia, and as age over 60 were associated with a negative impact on patient outcomes