Background/Purpose Inhibition of TGFβ signaling in human Embryonic Stem Cells (hESC) generates mesenchymal stromal cells (hESC-MSC) with osteogenic, adipogenic and chondrogenic potential. These cells have immunosuppressive and anti-inflammatory properties in vitro and have shown a protective effect in experimental models of acute inflammation. The aim of the present study was to test their therapeutic potential in an experimental setting of chronic inflammation, the collagen-induced arthritis model (CIA).

Methods Arthritis was induced in 8-10 weeks old male DBA/1 mice by intradermal immunization with 200 mcg of chicken type II collagen (CII) in Complete Freund´s Adjuvant (CFA). Mice were treated starting on the day of arthritis onset with three doses of 10⁶ cells / mouse hESC-MSC every other day and arthritis severity was evaluated daily during ten days. Effect of in vivo treatment was assessed by flow cytometry to detect Treg (FoxP3⁺), Th1 (IFNg⁺) and Th17 (IL17⁺) CD4 T cells in lymph nodes. To analyze T cell responses in vitro, lymph node cells were stimulated with CII, proliferation was measured by incorporation of the colorimetric reagent WST-1 and IFNg and IL17 levels were quantified by ELISA. Serum levels of anti-CII antibodies were determined by ELISA. Detection of ehESC-MSC in mouse tissues was performed by quantitative PCR (qPCR) of HLA-C and quantification of murine and human indoleamine 2,3 dioxygenase (IDO) was performed by quantitative PCR. Statistical differences were analyzed by ANOVA and Mann-Whitney U-test using GraphPad Prism software. P values < 0.05 were considered significant.

Results Treatment of CIA mice with hESC-MSC reduced diseased severity compared to control-treated mice. Differences appeared the first day after treatment and were significant and sustained in the group receiving 3 doses. Therefore, administration of 3 doses was the schedule used for subsequent experiments. Anti-CII antibodies levels were not affected by treatment. Analysis of CD4 T cell populations in treated mice showed an enrichment in FoxP3⁺ Treg cells (8.56 ± 0.89 % vs 5.89 ± 0.81% in control mice, *P= 0.026) in inguinal lymph nodes. IFNg producing cells were also increased (0.88 ± 0.09 % vs 0.54 ± 0.02 %, **P= 0.008) but not IL17 producing cells (0.93 ± 0.09 % vs 0.84 ± 0.05 %, P= 0.54). In vitro stimulation with CII caused higher production of IFNg and IL17 in lymph node cultures from hESC-MSC treated mice although not statistically significant (IFNg: 539.0 ± 219.3 pg/ml vs 147.8 ± 93.55 pg/ml, P= 0.09, IL17: 238.3 ± 134.1 pg/ml vs 72.39 ± 72.39 pg/ml, P= 0.24) and proliferation was not affected. hESC-MSC treated mice that showed MSC colonization in lymph nodes, as detected by HLA- expression, had significantly higher expression of murine indoleamine 2,3 dioxygenase than their treated non-colonized and not treated counterparts (6.88 ± 0,94 Units vs 1.049 ± 0,36 in non-colonized and 1.82 ± 0,24 in non-treated mices, **P= 0.009 and * *P= 0.004, respectively).

Conclusion Treatment with hESC-MSC ameliorates CIA by inducing IFNg and indoleamine 2,3 dioxygenase.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/treatment-of-collagen-induced-artritis-with-human-embrionic-stem-cell-derived-multipotent-mesenchymal-stromal-cells-hesc-msc/