Lithium mitigates early paneth cell loss in the ileum by enhancing lgr5⁺intestinal stem cell recovery. B6 Lgr5-GFP transgenic recipients were lethally irradiated (1000 cGy) and transplanted with BALB/c BM (10 × 10⁶) and purified splenic T cells (5 × 10⁶) with control or lithium diet treatment as described above. Ileum analysis at day +7 (A-B) and day +10 after HSCT (C-D) are shown. (A,C) Proportions of Lgr5-GFP^hi EpCAM⁺ ISC and lysozyme⁺ EpCAM⁺ Paneth cells in the ileum crypt, and the average of cytoplasmic lysozyme size in Paneth cells are shown. (C) Proportions of CD4⁺CD8^neg cells and CD8⁺CD4^neg cells in the ileum crypt are shown. (B,D) Representative multispectral images. Scale bar, 100 μm. Data at day 7 or day 10 (n = 5 per group). Data are presented as mean ± SEM. ∗P < .05; ∗∗∗∗P < .0001.