Background/Purpose: Previously we have shown that miR-663 was increased in bone marrow derived mesenchymal stem cells (BMSCs) from SLE patients and involved in the functional deficiency of BMSCs through inhibiting transforming growth factor b1 (TGF-b1) production. This study was undertaken to explore whether the modulation of miR-663 in BMSCs could affect their therapeutic effects on MRL/lpr mice.

Methods: Negative-control-miR-663 (miR-663-C), mimics-miR-663 (miR-663-M) and inhibitor-miR-663 (miR-663-I) eukaryotic expression vector were artificially transfected into BMSCs and intravenous injected (1°Á10⁶) into 20 weeks old female MRL/lpr mice. 8 weeks later, mice were sacrificed, with kidneys, lymph node harvested and spleen weighed. Their serum and urinary samples were collected for the measurement of autoantibodies (including IgG, ds-DNA and ANA) and cytokines (TGF-b1, IL-4, IFN-¦Ã, IL-17A and so on) by ELISA, and proteinuria by coomassie blue staining assay. Immune complex deposition including IgG and complement 3 (C3) in kidney sections was performed by immunofluorescence staining. The percentages of Th1, Th2, Th17, regulatory T cells (Treg) and follicular T helper (Tfh) cells in splenic mononuclear cells were detected by flow cytometry.

Results: Compared to the miR-663-C and miR-663-M group, miR-663-I transfected BMSCs displayed enhanced therapeutic effects on MRL/lpr mice, as shown by significantly declined spleens and lymph nodes size as well as reduced serum IgG and anti-dsDNA levels. Compared to miR-663-C and miR-663-I group, mice treated with miR-663-M transfected BMSCs presented enlarged glomerulus with hyper cellularity and meningeal expansion, and greater amounts of immune complex deposition including IgG and C3 in the meningeal and peripheral capillary loops. Meanwhile, Treg cell percentages were increased in miR-663-I group compared with those in miR-663-M and miR-663-C group (13.3±1.12% vs. 6.90±0.82% and 8.25±1.07%, overall p <0.05), while Tfh cell percentages were decreased (8.58±1.09% vs. 22.9±4.24% and 12.40±1.61%, overall p < 0.05).

Conclusion: Inhibition of miR-663 in MSCs enhanced the therapeutic effects of MSC transplantation on MRL/lpr mice.