Differentially expressed gene networks in cultured smooth muscle cells from normal and neuropathic bladder

Neuropathic bladder dysfunction results from abnormal development of the spine, spinal cord injuries, or diseases such as diabetics. Patients with neuropathic bladders often require surgical intervention such as bladder reconstruction to improve incontinence and prevent renal damage. Tissue engineering with ex-vivo cultured bladder cells has been suggested as one means for improving bladder function. However, we previously demonstrated that cultured bladder smooth muscle cells (SMCs) derived from neuropathic bladder exhibit and maintain altered pathologic phenotypes in culture. To identify genes that are responsible for the abnormal neuropathic phenotypes specifically elevated cell proliferation, the expression levels of 1,185 genes were compared between cultured SMCs derived from normal and neuropathic bladders using a cDNA array consisting of well-annotated genes. The expression data were analyzed using several methods to identify differentially expressed genes. The resulting sets of differentially expressed genes were examined by pathway analysis to identify the networks that remain abnormal in the culture-stable phenotype of neuropathic SMCs. A total of 18 genes that are differentially expressed between cultured normal and neuropathic bladder SMCs were identified. Of these 17 were up-regulated greater than 2-fold in neuropathic bladder SMCs, six of them along with one gene that was not up-regulated greater than 2-fold in cultured neuropathic bladder SMCs were confirmed and identified by more stringent analysis methods including significance analysis of microarrays, class comparison, and class prediction analyses. The major dysregulated pathways include fibroblast growth factor signaling, PTEN signaling, and integrin signaling. Our results further suggest that altered neuropathic bladder SMC phenotypes is stable in the culture environments and that SMCs derived from diseased bladders may not be appropriate for tissue engineering purpose without modification of pathologically altered genes expression.