Abstract

Mesenchymal Stromal-Stem Cells Promote Intestinal Epithelium Regeneration after Chemotherapy-Induced Damage

Magdalena Lorenowicz, Head of the Advanced In Vitro Model Systems Department, Biomedical Primate Research Center

Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative treatment for leukemia and a range of non-malignant congenital disorders. An essential component of HSCT is the conditioning regimen, consisting of chemotherapy and/or total body irradiation, administrated prior to hematopoietic cell infusion. The success of the therapy is hampered by the development of acute graft-versus-host-disease (aGvHD), in which immune cells from the donor attack healthy recipient tissue, including the liver, skin, and gut. Especially intestinal aGvHD is a life threatening complication. Data from our institution and others demonstrate rescue of ~50% of patients suffering from aGvHD with mesenchymal stromal cells (MSCs) in Phase II clinical trials. However, the underlying mechanism of MSCs contributing to steroid-resistant aGvHD treatment is still unknown. Current models in animal studies and homogeneous cell lines are highly relevant to the field, but these approaches are limited because of the high complexity of human tissues and organs. Immortalized and human primary cell lines have enabled detailed investigation of specific cell types, but do not recapitulate the cellular heterogeneity characteristics for physiological tissues. For this purpose, a suitable in vitro model is needed, which partially recapitulates the in vivo situation of GvHD patients and allows to study the mode of action of MSCs during organ/tissue regeneration in these patients. Here we developed a novel co-culture model of chemotherapy-induced small intestine damaged organoids, self-organizing 3D mini-guts derived from human stem cells, and MSCs and studied the regenerative aspects of MSC treatment on damaged intestinal epithelium by transcriptomic and proteomic analysis. Our study shows that busulfan, the chemotherapeutic commonly used as conditioning regimen before HSCT, damaged the small intestine epithelium by affecting pathways regulating epithelial mesenchymal transition, proliferation, and apoptosis. The MSCs reversed these effects by regulating genes and proteins involved in these pathways, which we also confirmed by functional evaluation of proliferation and apoptosis. Collectively, we demonstrate that our novel in vitro co-culture model is a new valuable tool to mimic the in vivo interplay between damaged intestinal epithelium and MSCs, providing a micro-physiological environment relevant to that of GvHD, and allows to study the molecular mechanism behind the therapeutic effects of MSCs in these patients.