Inflammatory Expression Profiles in Bladder Exstrophy Smooth Muscle: Normalization Over Time

To test the hypothesis that phenotypes in bladder exstrophy result from alterations in detrusor smooth muscle cell (SMC) gene expression.

We generated primary human bladder smooth muscle cell lines from patients with classic bladder exstrophy (CBE) undergoing newborn closure (n = 6), delayed primary closure (n = 5), augmentation cystoplasty (n = 6), and non-CBE controls (n = 3). Gene expression profiles were then created using RNA sequencing and characterized using gene set enrichment analysis (GSEA).

We identified 308 differentially expressed genes in bladder exstrophy SMC when compared to controls, including 223 upregulated and 85 downregulated genes. Bladder exstrophy muscle cell lines from newborn closure and primary delayed closures shared expression changes in 159 genes. GSEA analysis revealed increased expression in the inflammatory response and alteration of genes for genitourinary development in newborn and delayed closure SMC. However, these changes were absent in SMC from older exstrophy patients after closure.

Bladder exstrophy SMC demonstrate gene expression changes in the inflammatory response and genitourinary development. However, gene expression profiles normalized in exstrophy SMC from older patients after closure, suggesting a normalization of exstrophy SMC over time. Our in vitro findings regarding the normalization of exstrophy SMC gene expression following bladder closure suggest that the development of poor detrusor compliance in bladder exstrophy has a complex multifactorial etiology. Taken together, our findings suggest that alterations in SMC gene expression may explain abnormalities in the exstrophy bladder seen prior to and immediately after closure and suggest that surgical closure may allow exstrophy SMC to normalize over time.