Effects of Transplantation of CTLA4Ig-Overexpressing Adipose Tissue-Derived Mesenchymal Stem Cells in Mice with Sustained Severe Rheumatoid Arthritis

Abstract

CTLA4Ig has therapeutic potential for rheumatoid arthritis patients unresponsive to methotrexate (MTX) or TNF-α blockers. However, recombinant CTLA4Ig proteins are short acting and expensive. Adipose tissue-derived mesenchymal stem cells (ASCs) present an ideal stem cell source for practical regenerative medicine due to their abundant availability and their beneficial properties including immunomodulation, homing activity, paracrine effects, and differentiation ability. Therefore, we aimed to determine whether CTLA4Ig and human ASCs show synergistic effects on immunomodulation and clinical improvement of sustained severe rheumatoid arthritis in a mouse model. hASCs overexpressing CTLA4Ig (CTLA4Ig–hASC) were serially transplanted into mice with collagen-induced arthritis. Arthritic mice were subjected to four treatments based on their arthritis score on day 62 postimmunization: control (C group), hASC (H group), CTLA4Ig–hASC (CT group), and MTX (MTX group). A group of healthy mice was used as a normal control (N). Mice in the N and C groups were infused with 150 μl saline, and 2 × 106 hASCs or CTLA4Ig–hASCs in 150 μl of saline were intravenously administered to those in the H and CT groups, respectively, on days 63, 70, 77, and 84 after CII immunization. About 1 mg/kg of methotrexate was intraperitoneally administered to the MTX group three times a week for 4 weeks. Serial hASC and CTLA4Ig–hASC transplantation modulated various cytokines and chemokines related to the development of rheumatoid arthritis. Both treatments protected against destruction of cartilage, with CTLA4Ig–hASCs being most effective. Serum levels of CII autoantibodies and C-telopeptide of type II collagen were significantly low in the group transplanted with CTLA4Ig–hASCs. In vitro, ASC and CTLA4Ig–hASC treatment significantly decreased T-bet and GATA-3 expression in splenocytes from arthritic mice, and CTLA4Ig–hASC treatment significantly increased the ratio of Treg/Th17 (CD4+CD25+FoxP3+/CD4+CD25+RORγt) cells. Serial hASC and CTLA4Ig–hASC transplantation offers promising treatment for rheumatoid arthritis, and CTLA4Ig–hASCs showed stronger therapeutic effects than nontransduced hASCs.