17beta-estradiol induces the proliferation of the in vitro cultured human urothelium.
The genitourinary tract is considered to be a target for the actions of sex steroid hormones. Decreased ovarian function and lack of estrogen after menopause are associated with lower genitourinary tract symptoms as well as bladder dysfunctions such as incontinence. Estrogen may also affect urothelial cells. The estrogen receptors (ERs) are found in the mucosa of the urinary tract. The purpose of this study was to culture human urothelial cells (HUCs) originating from urothelial tissue biopsies and to use them as a reproducible test platform to evaluate the effect of 17beta-estradiol (E2). Urothelial tissue biopsies were obtained from 95 patients undergoing gynaecological open surgery for urinary incontinence, paediatric vesicoureteral reflux or transurethral resection of the prostate (TURP) for benign prostatic hyperplasia. HUCs originating from biopsies were cultured in vitro in the absence or in the presence of 0.1 nmol, 0.01 micromol and 1 micromol of E2. ER expression of the cultured HUCs was examined by Western analysis and immunofluorescence microscopy, which was also used for HUC characterization. The effect of E2 in the proliferation of the HUCs was determined by tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT)-assay. HUCs were cultured successfully in four to six passages but there was variation between samples. The cultured cells showed expression of beta(4)-integrin, E-cadherin and cytokeratins 7, 8, 9 and 19, indicating the epithelial origin of the cells. Both types of ERs, ERalpha and ERbeta, were found in the in vitro cultured HUCs. E2 treatment of HUCs did not affect remarkably the expression of ERalpha but cell proliferation was induced. However, no concentration-dependent effect was seen. This study indicates that HUCs originating from small tissue biopsies can be cultured in several passages in vitro and could have potential in repairing or restoring urinary tract tissue by tissue engineering therapy. HUCs serve as a good in vitro test platform, as shown by analysing E2-treated HUCs. E2 induced the proliferation of cultured HUCs even though concentration dependency was not observed. The findings of this study may have relevance in determining the mechanisms of estrogen therapy in postmenopausal urinary tract symptoms and in the future development of tissue engineering technology.