P117 Visfatin down-regulates growth promoting lncrna H19 during osteogenic differentiation of mesenchymal stromal cells

Career situation of first and presenting author Student for a master or a PhD. Introduction Osteoarthritis (OA) and osteoporosis are destructive bone diseases causing chronic pain and leading to disability. Mesenchymal stromal cells (MSC) are essential to bone health and tissue repair. Adipokines such as visfatin alter the osteogenic potential of MSCs and contribute to the loss of bone homeostasis. Long non-coding RNA H19 is one of the first lncRNAs discovered and relevant for distinct processes, e.g. during embryonic growth and tumor formation. lncRNAs interact directly with DNA, RNA as well as proteins, modulating transcription, protein expression and protein function. H19 upregulation was shown in osteogenic differentiation of MSCs.1 H19 increases the osteogenic potential via TGFβ1 and Wnt/β-catenin pathways.2 3 Objectives To investigate the influence of visfatin on H19 expression during osteogenesis. Methods Human MSCs from healthy donors (hMSC) and primary human MSCs from osteoarthritis patients (phMSC) after knee replacement surgery were treated with differentiation medium to induce osteogenic differentiation (OD). Matrix mineralization (MM) was quantified after 21 days by Alizarin Red. H19 expression by realtime PCR and IL-6 production by ELISA were measured. Results lncRNA H19 was up-regulated during OD. Although the H19 upregulation was not altered by co-stimulation with resistin, leptin or TNFα, visfatin co-stimulation during OD down-regulated H19 expression up to 10-fold as compared to unstimulated MSCs. The effect was significant in phMSCs at two of three measured time points (day 7 p=0.03; day 14 p=0.002, n=3) and in hMSCs at day 14 (p=0.0003, n=4). Visfatin co-stimulation of MSCs in OD increased MM, as well as IL-6 levels. However, TNF did not alter H19 expression or increase MM. Conclusions Visfatin co-stimulation during osteogenesis down-regulated lncRNA H19 expression, indicating a loss of the growthpromoting effects of lncRNA H19 in affected areas of destructive bone disease. This regulatory effect was specific to visfatin and did not occur upon co-stimulation with other adipokines or inflammatory stimuli such as TNF supporting a TNF-independent effect of visfatin. References Wang, L. Differential expression of long noncoding ribonucleic acids during osteogenic differentiation of human bone marrow mesenchymal stem cells. Int. Orthop. 2015;39:1013–1019. Huang, Y. Long Noncoding RNA H19 Promotes Osteoblast Differentiation Via TGF-?1/Smad3/HDAC Signaling Pathway by Deriving miR-675. Stem Cells 2015;33:3481–3492. Liang, W.-C. H19 activates Wnt signaling and promotes osteoblast differentiation by functioning as a competing endogenous RNA. Sci. Rep. 2012;6:20121. Disclosure of Interest None declared.