Bioactive factors secreted from mesenchymal stromal cells protect the intestines from experimental colitis in a three-dimensional culture

Background aims Although mesenchymal stromal cells (MSCs) have shown therapeutic potential in intestinal tissue repair, controversy concerning their short survival and poor biodistribution in recipient tissues still remains. Therefore, we investigated the paracrine role of MSC in three-dimensional culture of colon with experimental colitis. Methods Colitis was induced in mice by oral administration of dextran sulfate sodium (DSS) for 7 days. Inflammatory responses were assessed on the basis of clinical signs, morphological, and histopathological parameters. On days 2 and 5, colonic explants were removed, and a three-dimensional culture was performed. The structural integrity of the intestinal mucosa was tested by treating the cultures with MSC or conditioned medium (CM) for 24 h, and then the colons were analyzed for histology/immunohistochemistry and interleukin (IL)-6 production. Results Histological analysis demonstrated that both MSC and CM treatment reduced colon damage in organ culture. An increase in cell proliferation (Ki-67 staining) was observed after CM treatment. Additionally, MSC treatment was able to reduce CD3+ cells. The therapeutic effect of MSC and CM was mediated by the downregulation of IL-6. Discussion The intestinal in vitro model has shown to be potentially useful for studying cellular interactions in a three-dimensional cell arrangement. Moreover, our results provide strong evidence that both MSC and CM treatments can alleviate colonic damage in organ culture. Importantly, these results suggest that MSC-secreted factors are able to protect the colon from inflammation caused by DSS-induced colitis independent of cell transplantation.