(596h) The Effect of Heparin/ Poly(L-Lysine) Layer-By-Layer Coating in Immunomodulatory Functions of Mesenchymal Stromal Cells Stimulated By IFN-?

Human mesenchymal stromal cells (hMSCs) are multipotent cells that have been proposed for the treatment of immune-mediated diseases. The immunosuppressive properties of hMSCs can be enhanced using interferon‐gamma (IFN‐γ); however, pretreatment with IFN‐γ decreases hMSCs proliferation. The aim of this study is to use crosslinked multilayers of heparin and poly(L-lysine) (HEP/PLL) as a bioactive surface coating in order to reduce the effects of IFN‐γ on hMSCs proliferation while enhancing their immunosuppressive properties. Multilayers were formed, via layer-by-layer assembly, with HEP as the final layer and supplemented with IFN-γ in the culture medium. hMSCs adhesion, proliferation, and differentiation, were assessed. Results showed that HEP/PLL multilayer coatings were poorly adhesive for hMSCs. However, performing a chemical crosslinking using 1-ethyl-3-(3- dimethylaminopropyl) carbodiimide (EDC) significantly enhanced hMSCs adhesion and proliferation. The level of indoleamine 2,3-dioxygenase (IDO) secretion was evaluated with the activation of hMSCs by soluble IFN‐γ. Also, the possibility of inducing hMSCs to differentiate into osteoblasts and adipocytes was evaluated by exposing them to differentiation media specific to each lineage after IFN‐γ treatment. hMSCs differentiation was verified by staining using Alizarin Red (osteoblasts), and Oil-red O (adipocytes). Quartz crystal microbalance (QCM) experiments were conducted to evaluate the in-situ adhesion of IFN‐γ to HEP/PLL films. This study suggests that crosslinked HEP/PLL films can modulate hMSCs response to soluble factors, which may improve hMSCs-based therapies aimed at treating several immune diseases.