Cell dedifferentiation and epithelial to mesenchymal transitions during intestinal regeneration in H. glaberrima

We have now obtained a monoclonal antibody that labels the mesothelium; the outer layer of the gut wall composed of peritoneocytes and myocytes. Using this antibody we studied the role of this tissue layer in the early stages of intestinal regeneration. We have now shown that the mesothelial cells of the mesentery, specifically the muscle component, undergo dedifferentiation from very early on in the regeneration process. Cell proliferation, on the other hand, increases much later, and mainly takes place in the mesothelium or coelomic epithelium of the regenerating intestinal rudiment. Moreover, we have found that the formation of the intestinal rudiment involves a novel regenerative mechanism where epithelial cells ingress into the connective tissue and acquire mesenchymal phenotypes.Our results strongly suggest that the dedifferentiating mesothelium provides the initial source of cells for the formation of the intestinal rudiment. At later stages, cell proliferation supplies additional cells necessary for the increase in size of the regenerate. Our data also shows that the mechanism of epithelial to mesenchymal transition provides many of the connective tissue cells found in the regenerating intestine. These results present some new and important information as to the cellular basis of organ regeneration and in particular to the process of regeneration of visceral organs.In recent years, investigators have shown a renewed interest in regenerative phenomena. In view that many "classical" model system organisms show limited regenerative capacities, research on non-traditional model systems has flourished. Many of these organisms, such as planarians and Hydra, had been studied previously, some for almost three centuries. However, modern cellular and molecular tools have permitted a novel look into these regeneration models and a re-examination of the cellular and molecular mechanisms involved in the regenerative events [1].Crucial to the understanding of organ or lim