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P077. Effects of IFN-γ priming on the functional characteristics of human bone marrow and adipose derived mesenchymal stem cells expanded in alternative xeno-free conditions

A. Oikonomopoulos, W.K. van Deen, D.W. Hommes, UCLA Center for Inflammatory Bowel Diseases, Division of Digestive Diseases, Los Angeles, United States

Background

Human Bone Marrow and Adipose derived Mesenchymal Stem Cells (BMMSC and AdMSC) hold great promise for the treatment of immunological disorders such as IBD. Clinical application of MSC requires ex vivo manufacturing utilizing animal serum as growth supplement. Avoiding immunological complications requires evaluation of alternative xeno-free media. Moreover, recent studies have showed that stimulation (priming) of MSC with cytokines (IFN-γ) augments their immunosuppressive properties. In the current study we tested the functional properties of BMMSC and AdMSC expanded in xeno-free media following IFN-γ priming.

Methods

Human donor-derived BMMSC and AdMSC were expanded in the presence of 5%, 10% human platelet lysates (HPL) or xeno-free medium (GIBCO) or in 10% FBS (control). Cell size (area) was monitored by microscopy. MSC were primed with IFN-γ (50 ng/mL) for 72 hours. Immunophenotypic profile of MSC was performed by flow cytometry. MSC proliferation rate was determined by BrdU assays. Immunomodulatory properties of resting (non-primed) and primed MSC were accessed by co-culture assays with human peripheral blood mononuclear cells (PBMC) and gene expression analysis of indoleamine 2, 3-dioxygenase (IDO1).

Results

IFN-γ priming increased significantly BMMSC and AdMSC size in FBS but not in other media. Resting BMMSC and AdMSC showed significantly smaller size in HPL compared to xeno-free and FBS. IFN-γ priming did not affect the expression of CD73 and CD90 in MSC in all media. Resting and primed BMMSC and AdMSC showed decreased expression of CD105 in HPL media and in xeno-free media respectively. Primed BMMSC showed reduced induction of HLA-DR in xeno-free and in 5% and 10% HPL compared to FBS. No effects were detected in the induction of HLA-DR following priming on the AdMSC. Additionally, the proliferation capacity of BMMSC and AdMSC in all media was significantly increased compared to FBS. However, IFN-γ priming decreased the proliferation capacity of BMMSC and AdMSC in all media. Resting BMMSC and AdMSC showed potent immunosuppressive properties that were further potentiated by IFN-γ priming in FBS- and xeno-free medium. In contrast, HPL-expanded MSC lost their immunosuppressive properties in resting and primed conditions. Finally, BMMSC and AdMSC in HPL and in xeno-free medium showed decreased IDO1 expression compared to cells expanded in FBS.

Conclusion

Our data show that xeno-free medium but not HPL can be applied for MSC ex vivo manufacturing towards therapeutic applications. Moreover, IFN-γ priming affects dramatically the growth potential of BMMSC and AdMSC in all media. This is the first thorough insight on the effects of IFN-γ priming on MSC in alternative xeno-free media.