Successful engraftment of bladder organoids in de-epithelialized mouse colon.

ABSTRACT

PURPOSE: To engraft bladder organoids (BO) on de-epithelialized mouse colon using an epithelial replacement technique. METHODS: BO cultured using bladder specimens from enhanced green fluorescent protein (EGFP) transgenic mice were engrafted to replace proximal colon epithelium stripped from an approximately 1 cm long target site in syngeneic wild-type recipient mice (n = 9) by exposure to ethylenediaminetetraacetic acid by infusion and flushing with phosphate buffered saline. Target sites were harvested on postoperative days 2, 7, and 28 for hematoxylin-eosin staining and immunofluorescence. RESULTS: Histology on postoperative days 7 and 28 showed BO derived EGFP + cells forming multiple layers on the luminal surface of the colon. Immunohistochemistry showed that EGFP + areas were positive for CK5 and CK14, markers for basal and immature subtype urothelium, respectively, but negative for CA2, a marker for colonic epithelium. Ki67 was detected predominantly in the basal parts of EGFP + areas on postoperative day 7 and day 28. CONCLUSIONS: This is the first report of successful engraftment of BO in de-epithelialized colon with urothelial tissue reconstituted by actively proliferating cells. This technique could be developed for augmentation cystoplasty to prevent bladder calculi formation and malignant transformation.