Investigating the relevance of simulated urination for a urethra-on-a-chip

Abstract

Introduction: Urethral stricture disease (USD) is prevalent among older men and can necessitate urethroplasty and tissue grafting. Regenerative medicine has the potential to create new therapies for USD using advanced organ-on-a-chip (OOC) models. Parameters must be optimized in OOC to create in-vivo-accurate models, and this study investigates the role of flow intermittent in culturing urethral cells with physiological phenotypes. Methods: Porcine urethral epithelial cells (pUECs) and human buccal mucosa cells (hBMCs) were cultured, and one medium was optimized to support them both. The cells underwent flow experiments in which they were subject to constant, intermittent, or no shear stress. Some of these cells were fluorescently stained for zonula occludins-1 (ZO-1), as well as other markers, and imaged, while the others were processed for use in quantitative polymerase chain reaction (qPCR) assays. SEM images made from pig penile tissue were analyzed along with fluorescent cell images for alignment to flow and elongation. Statistical analysis was performed for comparison between different shear stress conditions. Results: Intermittent flow led to significantly more elongated pUECs than those under constant flow or in tissue and significantly less aligned cells than in tissue. hBMCs were not quantified. Conclusions: Intermittent flow alone does not induce physiological morphology in pUECs. Functional metrics are needed before drawing further conclusions. Comparison to hBMCs should be done, and other parameters for recapitulating the native urethra should be considered for future iterations of the in-vitro urethra model.