Evaluation of radiation-induced intestinal injury via a new human intestinal organ-on-a-chip model

To establish a human intestinal organ-on-a-chip model using a multi-array chip array to simulate the microphysiological structure of the human intestine and to investigate the impact of ionizing radiation on radiation-induced damage to human intestinal cells.

Caco-2 and human umbilical vein endothelial cells (HUVECs) were co-cultured in an organ chip. The cells were subjected to fluid shear stress via a precision shaker. After 7 days of dynamic culture,the morphological structure of intestinal epithelial cells and venous endothelial cells within the intestinal organ chip was examined using phase contrast microscopy,immunofluorescence staining,and confocal microscopy for three-dimensional (3D) imaging. γ-H2AX and TUNEL immunofluorescence staining were employed to assess DNA damage and apoptosis in intestinal epithelial cells two days post-irradiation. Villin immunofluorescence staining was used to evaluate villus height three days post-irradiation. EdU incorporation assay and Ki67 immunofluorescence staining were conducted to observe the effects of ionizing radiation on the proliferation of intestinal epithelial cells.

After 7 days of dynamic culture,phase contrast microscopy and immunofluorescence staining combined with confocal 3D imaging revealed that the upper intestinal epithelial cells in the middle compartment of the chip formed a 3D intestinal villus structure,while the vascular endothelial cells in the lower compartment developed a vascular network structure. The chip was subsequently irradiated by 10 Gy X-ray. Immunofluorescence staining results indicated that the mean fluorescence intensity of γ-H2AX and TUNEL in the irradiated group was significantly higher than in the non-irradiated group 2 days after irradiation (P<0.01),and that the proportion of EDU⁺ and Ki67⁺ cells in the irradiated group was significantly lower than in the non-irradiated group three days after irradiation (P<0.05).

Caco-2 cells and HUVECs co-culture on an organ chip can generate the biomimetic structure of human intestinal villus. Ionizing radiation has been found to shorten intestinal villus,increase DNA damage and apoptosis in intestinal epithelial cells,and inhibit the proliferation of these cells.