Fig. 2.

Surface engineering of human fibroblasts and mouse primary IECs via mild reduction. (A) Illustration of cell surface modification by mild reduction using TCEP; maleimide-conjugated green fluorescent dye (Mal-Alexa Fluor 488) was used to visualize thiol. (B) (Top) Confocal microscopic images of (i) small intestinal epithelial cells, (ii) colonic epithelial cells, and (iii) human fibroblasts. (Bottom) The presence of free thiol on cell surface was visualized with Mal-Alexa Fluor 488. Scale bar = 10 μm. (C) Ellman’s assay demonstrating the relative amount of free thiol produced by TCEP with varying concentrations (0 to 1 mM). (D) Viability of reduced cell compared to nontreated cell in different concentrations of TCEP. **P < 0.01 and ***P < 0.001 vs. the nontreated group (0 mM); n = 4 in panels C and D.