The therapeutic effect of NeuroD on radiation-induced intestinal injury in mice

Objective: To evaluate the therapeutic effect of NeuroD protein on radiation-induced intestinal injuries. Methods: The expression and purification of NeuroD-enhanced green fluorescent protein (EGFP) fusion protein was performed in prokaryotic expression system. The efficiency of the fusion protein transduction into cells was monitored under fluorescence microscope. C57BL/6J mice were randomly divided into four groups with 10 mice in each group: normal control group, PBS group, EGFP group, and NeuroD-EGFP group. Besides the normal control group, the other three groups of mice received 9 Gy γ-ray total body irradiation. Intestinal tissues were collected, frozen sections were prepared to monitor the distribution of NeuroD in mice intestinal tract under fluorescence microscope, and pathological sections were prepared for H&E staining to evaluate the therapeutic effect of NeuroD protein. Results: The NeuroD-EGFP fusion protein was purified by Ni-NTA column and verified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Visible green fluorescence gathered within the cells after NeuroD-EGFP fusion protein was added in the culture medium, suggesting that NeuroD-EGFP could penetrate the cell membrane into the cells. Five hours after intraperitoneal injection of NeuroD-EGFP, visible green fluorescence gathered within the intestinal epithelial cells in villi. At 3.5 d after irradiation, NeuroD-EGFP treated mice showed significantly higher villus (F = 49.49, P < 0.01) and crypt depth (F = 16.72, P < 0.01) and more crypts per circumference (F = 10.32, P < 0.01) compared with PBS and EGFP groups. Conclusion: NeuroD protein can accelerate the post-irradiation recovery of injured villi and crypt of intestinal tract and could be used to treat radiation-induced intestinal injuries. (authors)