Comparison of the anti-inflammatory effects of induced pluripotent stem cell-derived and bone marrow-derived mesenchymal stromal cells in a murine model of corneal injury.

Mesenchymal stromal cells (MSCs) offer tremendous potential for therapeutic applications for inflammatory diseases. However, tissue-derived MSCs, such as bone marrow-derived MSCs (BM-MSCs), have considerable donor variations and limited expandability. It was recently demonstrated that MSCs derived from induced pluripotent stem cells (iPSC-MSCs) have less pro-tumor potential and greater expandability of homogenous cell population. In this study, we investigated the anti-inflammatory effects and mechanism of iPSC-MSCs in a murine model of chemical and mechanical injury to the cornea and compared the effects with those of BM-MSCs. To create an injury, ethanol was applied to the corneal surface in mice, and the corneal epithelium was removed with a blade. Immediately after injury, mice received an intravenous injection of (i) iPSC-MSCs, (ii) BM-MSCs or (iii) vehicle. Clinical, histological and molecular assays were performed in the cornea to evaluate inflammation. We found that corneal opacity was significantly reduced by iPSC-MSCs or BM-MSCs. Histological examination revealed that the swelling and inflammatory infiltration in the cornea were markedly decreased in mice treated with iPSC-MSCs or BM-MSCs. Corneal levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 were lower in iPSC-MSC- and BM-MSC-treated mice, compared with vehicle-treated controls. In contrast, iPSC-MSCs with a knockdown of the TNF-α stimulating gene (TSG)-6 did not suppress the levels of inflammatory cytokines and failed to reduce corneal opacity. Together these data demonstrate that iPSC-MSCs exert therapeutic effects in the cornea by reducing inflammation in part through the expression of TSG-6, and the effects are similar to those seen with BM-MSCs.