An investigation into the effects of short-chain fatty acids on primary and transformed urothelial cells in relation to their potential as an intravesical agent in the neobladder

Dyer, Jonathan Paul (2007) An investigation into the effects of short-chain fatty acids on primary and transformed urothelial cells in relation to their potential as an intravesical agent in the neobladder. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

Colocystoplasty has an important role in bladder reconstructive surgery. However it can be affected by chronic inflammation and excessive mucous production which may lead to urinary tract infection, stone formation and occasionally malignant transformation. We postulate that changes in the colonic segment within the augmentation are affected by a condition known as diversion colitis, which is found in bowel segments diverted away from the faecal stream. The aetiology of this condition is a luminal deficiency of short chain fatty acids (SCFAs) which are produced by bacterial fermentation of dietary fibre and include butyrate, propionate and acetate. Studies have shown that they are the colonocytes’ preferred energy substrate and have an important role in chronic mucosal health and prevention of malignant transformation.

The purpose of this study was to investigate the effect of SCFAs on the bladder which is an important consideration when contemplating intraversical therapy in colocystoplasty. Using monolayer cell cultures of both primary urothelial cells and urothelial cancer cell lines the effects of SCFAs were investigated. The MTT (3-[4,5-dimethyl thiazol-2-yl]-2,5-diphenyltetrazolium bromide; thiazolyl blue) cytotoxicity assay was employed to study cell growth. Fluorescence microscopy with acridine orange and flow cytometry were used to study apoptosis and the cell cycle. It was found that all three SCFAs inhibit cell growth, induce apoptosis and induce cell cycle arrest. Butyrate had the most potent effect in vitro followed by propionate and then acetate. To assess the significance of these results in vivo, intravesical instillation of SCFAs was performed in a rodent model which demonstrated no significant adverse effects both histologically and on urothelial cell turnover.

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