In Vitro Bladder Cancer Models

Over the past five decades, in vitro models of bladder cancer (BLCA) have been instrumental in understanding tumor biology. These models offer many advantages over animal testing, including bypassing ethical concerns associated with in vivo experiments, cost-effectiveness, and suitability for high-throughput studies like testing small compounds and genetic screens. We review the main in vitro BLCA models, including 2D plastic cultures and more recent three-dimensional (3D) systems such as organoids, tumoroids, and assembloids. Conventional BLCA cell lines are still the primary option for many studies, mainly due to their simple requirements and rapid growth. However, they display shortcomings, favoring the use and optimization of culture techniques designed to tackle these limitations. 3D systems excel regarding efficiency of sustained growth upon primary culture, recapitulating tumor-of-origin features, and usefulness. However, challenges persist, including price, the absence of standardized procedures for establishment and maintenance, and the fact that they generally lack the stroma. Hence, advanced organotypic systems are an important solution to overcome some of these limitations, along with the emergence of nanotechnology and microfluidics advancements that are poised to shape this field in the upcoming decade. Additionally, we discuss the relevance of culturing normal urothelial cells alongside BLCA cells for a better comprehension of cancer-associated biology.