The role of estrogen in the accelerating regeneration of the intestinal mucosa and the presence of estrogen receptors on the surface of mesenchymal stem cells (stimulator of proliferation and differentiation of MSC) led us to investigate the role of the supernatant of mesenchymal stem cells containing 17-beta estradiol in the histopathological changes of the colon of rats suffering from ulcerative colitis (UC). Following the induction of ulcerative colitis in all groups (colitis (C), mesenchymal (MSC) and MSC + estradiol (MSC + EST)) except the control, in 2 groups MSC and MSC + EST respectively: 200 µl supernatant of 2x106 mesenchymal stem cells and 200 µl supernatant of 2x106 mesenchymal stem cells treated with 17-bED were injected 3 times during 10 days (IP). After the experimental period, Tissue specimens were collected and following the tissue passage and section, the slides were stained by H&E for histopathological evaluations. The results obtained from the colon tissue of the C group showed the presence of many inflammatory cells in the mucous layer (the space between the crypts), many eosinophilic cells in the sub-epithelial, collagenous colitis in the mucosa, severe vascular congestion in the sub-mucosa and as well as the loss of normal structure of the epithelial cells. In the mucosal layer of MSC groups and especially MSC + EST, inflammatory cells were seen scattered along with a decrease in eosinophil cells and collagenous colitis. Mild to moderate vascular congestion and loss of epithelial cells and crypts were reported in some areas. The present study showed the improvement of histopathological symptoms caused by the induction of UC following the use of mesenchymal stem cell supernatant, especially in MSC + EST group.
