Many studies have drawn attention to the emerging role of MSC (mesenchymal stem cells) as a promising population supporting new clinical concepts in cellular therapy. However, the sources from which these cells can be isolated are still under discussion. Whereas BM (bone marrow) is presented as the main source of MSC, despite the invasive procedure related to this source, the possibility of isolating sufficient numbers of these cells from UCB (umbilical cord blood) remains controversial. Here, we present the results of experiments aimed at isolating MSC from UCB, BM and UCM (umbilical cord matrix) using different methods of isolation and various culture media that summarize the main procedures and criteria reported in the literature. Whereas isolation of MSC were successful from BM (10:10) and (UCM) (8:8), only one cord blood sample (1:15) gave rise to MSC using various culture media [DMEM (Dulbecco's modified Eagle's medium) +5% platelet lysate, DMEM+10% FBS (fetal bovine serum), DMEM+10% human UCB serum, MSCGM] and different isolation methods [plastic adherence of total MNC (mononuclear cells), CD3+/CD19+/CD14+/CD38+-depleted MNC and CD133+- or LNGFR+-enriched MNC]. MSC from UCM and BM were able to differentiate into adipocytes, osteocytes and hepatocytes. The expansion potential was highest for MSC from UCM. The two cell populations had CD90+/CD73+/CD105+ phenotype with the additional expression of SSEA4 and LNGFR for BM MSC. These results clearly exclude UCB from the list of MSC sources for clinical use and propose instead UCM as a rich, non-invasive and abundant source of MSC.

Background: The 21-kDa Vaccinia virus VH1-related (VHR) dual-specific protein phosphatase (encoded by the DUSP3 gene) plays a critical role in cell cycle progression and is itself regulated during the cell cycle. We have previously demonstrated using RNA interference that cells lacking VHR arrest in the G1 and G2 phases of the cell cycle and show signs of beginning of cell senescence.

It was shown recently that synovial fibroblast transformation into adipocytes reduced the expression of interleukin-6 (IL-6) and IL-8. However, the synovial fibroblast adipogenesis was inhibited in inflammatory conditions induced by the tumor necrosis factor-a (TNF-a). Furthermore, adipogenesis is often accompanied by leptin production, a proinflammatory adipokine in rheumatic diseases. In this study, we tested the phytohormone genistein for adipogenic and anti-inflammatory properties on human synovial fibroblasts. Results showed that genistein was able to transform synovial fibroblasts into adipocytes that expressed perilipin-A and produced adiponectin, but not leptin. Furthermore, genistein enhanced glucocorticoid-mediated synovial fibroblast adipogenesis and, in parallel, downregulated glucocorticoid-induced leptin and leptin receptor. Endogenous and TNF-a-induced expressions of IL-6, IL-8, p38, p65 and C/EBP-b were also downregulated by genistein, showing its anti-inflammatory properties. Peroxisome proliferatoractivated receptor-g (PPAR-g) agonist, rosiglitazone, had a synergic effect on genistein-induced adipogenesis, whereas the non-active tyrosine kinase inhibitor, daidzein, had a significantly inferior adipogenic activity than genistein. The Janus kinase-2 tyrosine kinase inhibitor, AG 490, mimicked the anti-leptin effect of genistein. These results showed that genistein-induced adipogenesis involves PPAR-g induction and tyrosine kinase inhibition. In conclusion, genistein, alone or coupled with glucocorticoids, have both adipogenic and anti-inflammatory effects on synovial fibroblasts.

Leptin plays a central role in maintaining energy balance, with multiple other systemic effects. Despite leptin importance in peripheral regulation of mesenchymal stem cells (MSC) differentiation, little is known about its expression mechanism. Leptin is often described as adipokine, while it is expressed by other cell types. We have recently shown an in vitro leptin expression, enhanced by glucocorticoids in synovial fibroblasts (SVF). Here, we investigated leptin expression in MSC from bone marrow (BM-MSC) and umbilical cord matrix (UMSC). Results showed that BM-MSC, but not UMSC, expressed leptin that was strongly enhanced by glucocorticoids. Transforming growth factor b1 (TGF-b1) markedly inhibited the endogenous-and glucocorticoid-induced leptin expression in BM-MSC. Since TGF-b1 was shown to signal via ALK-5-Smad2/3 and/or ALK-1-Smad1/5 pathways, we analyzed the expression of proteins from both pathways. In BM-MSC, TGF-b1 increased phosphorylated Smad2 (p-Smad2) expression, while ALK-5 inhibitor (SB431542) induced leptin expression and significantly restored TGF-b1-induced leptin inhibition. In addition, both prednisolone and SB431542 increased p-Smad1/5 expression. These results suggested the ALK-5-Smad2 pathway as an inhibitor of leptin expression, while ALK-1-Smad1/5 as an activator. Indeed, Smad1 expression silencing induced leptin expression inhibition. Furthermore, prednisolone enhanced the expression of TGF-bRII while decreasing p-Smad2 in BM-MSC and SVF but not in UMSC. In vitro differentiation revealed differential osteogenic potential in SVF, BM-MSC, and UMSC that was correlated to their leptin expression potential. Our results suggest that ALK-1/ALK-5 balance regulates leptin expression in MSC. It also underlines UMSC as leptin nonproducer MSC for cell therapy protocols where leptin expression is not suitable.

MAIDS (murine AIDS) is caused by infection with the murine leukaemia retrovirus RadLV-Rs and is characterized by a severe immunodeficiency and T-cell anergy combined with a lymphoproliferative disease affecting both B- and T-cells. Hyperactivation of the cAMP-protein kinase A pathway is involved in the T-cell dysfunction of MAIDS and HIV by inhibiting T-cell activation through the T-cell receptor. In the present study, we show that MAIDS involves a strong and selective up-regulation of cyclo-oxygenase type 2 in the CD11b+ subpopulation of T- and B-cells of the lymph nodes, leading to increased levels of PGE2 (prostaglandin E2). PGE2 activates the cAMP pathway through G-protein-coupled receptors. Treatment with cyclo-oxygenase type 2 inhibitors reduces the level of PGE2 and thereby reverses the T-cell anergy, restores the T-cell immune function and ameliorates the lymphoproliferative disease.

No abstract

CpdA, unlike prednisolone, did not induce leptin or Ob-R in human OA synovial fibroblasts, thereby demonstrating an improved risk:benefit ratio.

Only dedifferentiated OA chondrocytes produced leptin. Prednisolone markedly enhanced leptin production, which involved Smad1 and β-catenin activation.