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

Abstract

To engraft bladder organoids (BO) on de-epithelialized mouse colon using an epithelial replacement technique. BO cultured using bladder specimens from enhanced green fluorescent protein (EGFP) transgenic mice were engrafted to replace proximal colon epithelium stripped from an approximately 1cm long target site in syngeneic wild-type recipient mice (n = 9) by exposure to ethylenediaminetetraaceticacid 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. Histology on postoperativedays7 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 postoperativeday7 and day 28. 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.