Is bladder outlet obstruction rat model to induce overactive bladder (OAB) has similarity to human OAB? : Research on the events in smooth muscle, collagen, interstitial cell and telocyte expression

Abstract

Abstract Background Cellular and cytoskeletal events of overactive bladder (OAB) have not been sufficiently explored in human bladder due to different limitations. Bladder outlet obstruction (BOO) had been induced with different methods to induce overactive bladder (OAB). Similarity of the animal models of BOO to the human OAB is postulated, but has not been confirmed. The interstitial cells of cajal (ICCs) and telocyted (TCs) is an important player in smooth muscles conductivity, they had not been well investigated in previous works. Objectives investigating the morphological pattern of cellular, cytoskeleton and telocyte expression in BOO rat model and compare it to the findings in real-world human OAB. Methods Female Sprague-Dawley rats were randomly divided into BOO group (n = 20), and control group (n = 10). Sex weeks and 8 week were chosen to evaluate the effect of time of BOO on the bladder changes. After 6 weeks (n= 10) and 8 weeks (n=10) of induction of BOO, and the control-sham group (n= 10) the bladder was examined with histopathologically, immunohistochemistry (IHC), and transmission electron microscopy (EM). The dataset of human OAB were extracted from an open access published data comprised 5 cases of OAB that undergone similar investigations. Results Animal model: Histological examination of the bladder wall after 6 & 8 weeks of BOO shows thinner urothelium, and condensation of collagen between muscle bundles. IHC with c-Kit shows excess expressed of ICCs between smooth muscle bundles. EM shows frequent expression TCs that were situated between collagen fibers. The dataset of human OAB there was similarity to the finding in the animal model. Human OAB: showed similar findings. Conclusion The animal model study demonstrated increased collagen/ smooth muscle ratio, high intensity of ICCs and presence of TCs. In the human study, identical investigations showed similarities in the changes of smooth muscle cells and cytoskeleton. These findings confirm that a minimillally invasive procedure to induce BOO to result in an OAB has a morphological similarity to the human OAB. The expression of TCs in both animal model and human OAB warrant further study to define its role in OAB.