Figure 2. MSC-CM^IEC-6(IR) restores intestinal functionality and structure of irradiated rats.

(A) Changes of intestinal electrolyte transport were measured by short-circuit current analysis (I_sc) in response to electrical filed stimulation (EFS). (left panel) I_sc response was stimulated by increasing frequencies of EFS ranging from 1 ~ 25 Hz. (right panel) I_sc response was studied 1, 3, 7 days after irradiation. Data are expressed as the change in I_sc and are the mean ± SD for n = 6 animals. **, P < 0.05 versus IR + DMEM-F12, ##, P < 0.05 versus IR + MSC-CM^IEC-6(NOR). (B) D-Xylose absorption tests were performed at 1, 3, 7 days after irradiation. Values represent means ± SD of n = 3 animals, **, P < 0.05 versus IR + DMEM-F12, ##, P < 0.05 versus IR + MSC-CM^IEC-6(NOR). (C) Intestinal permeability, measured as plasma level of D-lactate, was measured at 1, 3, 7 days after irradiation. Values represent means ± SD of n = 3 animals, **, P < 0.05 versus IR + DMEM-F12, ##, P < 0.05 versus IR + MSC-CM^IEC-6(NOR). (D) Histological analysis by H&E staining. Scale bars 100 μm. (E) Morphometric evaluation of epithelium thickness. Each value represents the average of 20 independent measurements per animal (six animals per group). **, P < 0.05 versus IR + DMEM-F12, ##, P < 0.05 versus IR + MSC-CM^IEC-6(NOR). (F) The morphological changes of intestinal tight junction after radiation. The structures between the adjoining cells were observed under transmission electron microscopy. Arrows, tight junctions; bars, 500 nm. IR + DMEM-F12, irradiated rats receiving DMEM-F12; IR + FB-CM^IEC-6(IR), irradiated rats receiving FB-CM^IEC-6(IR); IR + MSC-CM^IEC-6(NOR), irradiated rats receiving MSC-CM^IEC-6(NOR); IR + MSC-CM^IEC-6(IR), irradiated rats receiving MSC-CM^IEC-6(IR).