[Establishment and Evaluation of Intestinal Injury Model of Mouse Acute Graft Versus Host Disease Based on An Organoid Technology].

Objective: To establish an intestinal organoid model that mimic acute graft versus host disease (aGVHD) caused intestinal injuries by using aGVHD murine model serum and organoid culture system, and explore the changes of aGVHD intestine in vitro by advantage of organoid technology.

Methods: 20-22 g female C57BL/6 mice and 20-22 g female BALB/c mice were used as donors and recipients for bone marrow transplantation, respectively. Within 4-6 h after receiving a lethal dose (8.0 Gy) of γ ray total body irradiation, a total of 0.25 ml of murine derived bone marrow cells (1×10/mice, =20) and spleen nucleated cells (5×10/mice, =20) was infused to establish a mouse model of aGVHD (=20). The aGVHD mice were anesthetized at the 7th day after transplantation, and the veinal blood was harvested by removing the eyeballs, and the serum was collected by centrifugation. The small intestinal crypts of healthy C57BL/6 mice were harvested and cultivated in 3D culture system that maintaining the growth and proliferation of intestinal stem cells in vitro. In our experiment, 5%, 10%, 20% proportions of aGVHD serum were respectively added into the organoid culture system for 3 days. The formation of small intestinal organoids were observed under an inverted microscope and the morphological characteristics of intestinal organoids in each groups were analyzed. For further evaluation, the aGVHD intestinal organoids were harvested and their pathological changes were observed. Combined with HE staining, intestinal organ morphology evaluation was performed. Combined with Alcian Blue staining, the secretion function of aGVHD intestinal organoids was observed. The distribution and changes of Lgr5 and Clu intestinal stem cells in intestinal organoids were analyzed under the conditions of 5%, 10% and 20% serum concentrations by immunohistochemical stainings.

Results: The results of HE staining showed that the integrity of intestinal organoids in the 5% concentration serum group was better than that in the 10% and 20% groups. The 5% concentration serum group showed the highest number of organoids, the highest germination rate and the lowest pathological score among experimental groups, while the 20% group exhibited severe morphological destruction and almost no germination was observed, and the pathological score was the highest among all groups(=3.668, 4.334,5.309,<0.05). The results of Alican blue staining showed that the secretion function of intestinal organoids in serum culture of aGVHD in the 20% group was weaker than that of the 5% group and 10% of the organoids, and there was almost no goblet cells, and mucus was stainned in the 20% aGVHD serum group. The immunohistochemical results showed that the number of Lgr5 cells of intestinal organoids in the 5% group was more than that of the intestinal organoids in the 10% aGVHD serum group and 20% aGVHD serum group. Almost no Clu cells were observed in the 5% group. The Lgr5 cells in the 20% group were seriously injuried and can not be observed. The proportion of Clu cells in the 20% group significantly increased.

Conclusion: The concentration of aGVHD serum in the culture system can affect the number and secretion function of intestinal organoids as well as the number of intestinal stem cells in organoids. The higher the serum concentration, the greater the risk of organoid injury, which reveal the characteristics of the formation and functional change of aGVHD intestinal organoids, and provide a novel tool for the study of intestinal injury in aGVHD.