Topical corticosteroids damage Lgr5⁺HFSCs and induce loss of hair follicles and fat-layer atrophy in the skin. (A-J) Lethally irradiated B6 or B6-Lgr5^EGFP-cre/ER mice were transplanted as in Figure 1, followed by daily administration of control Vaseline (Ctrl), betamethasone valerate ointment 0.12% (BMV), or clobetasol propionate ointment 0.05% (CP) on their shaved back skin from day +1 after SCT. (A) Numbers of infiltrating donor T cells on day +14 after SCT from 2 independent experiments (n = 8 per group). Representative macroscopic images (B), H&E staining of the skin sections (C), numbers of hair follicles (D), and thickness of fat layer (E) in treated skin on day +50 after SCT. Data from 2 independent experiments were combined (n = 6-7 per group). The area surrounded by a dashed line shows treated skin with each ointment. Original magnification ×10. Scale bar, 100 μm. (F) EGFP⁺ cells in 50 follicles of treated skin on day +14 after SCT from 2 independent experiments (n = 6-7 per group). (G-J) Lethally irradiated B6 or B6-Lgr5^EGFP-cre/ER mice were transplanted with 5 × 10⁶ bone marrow cells and 5 × 10⁶ splenocytes from syngeneic B6 mice and administrated daily with each ointment onto back skin for 3 weeks after SCT. Numbers of hair follicles (G) (n = 10 per group), thickness of fat layer (H) (n = 10 per group), and numbers of EGFP⁺ cells in 50 follicles (I) (n = 7 per group) from 2 independent experiments were combined. (J) Representative immunofluorescent images of EGFP (green), CK15 (red), and DAPI (blue) of the treated skin and nontreated skin of the syngeneic animal. Original magnification ×40. Scale bar, 50 μm. One-way ANOVA followed by the Tukey posttest was used to compare the data (***P < .005; **P < .01). Data represent the mean ± SEM.