Patient-derived organoid co-culture systems as next-generation models for bladder cancer stem cell research.

Three-dimensional patient-derived organoids (PDOs) have emerged as a powerful model for investigating the molecular and cellular mechanisms underlying bladder cancer, particularly in the context of cancer stem cells (CSCs) and drug screening. However, a significant limitation of conventional PDOs is the absence of tumor microenvironment (TME), which includes critical stromal, immune and microbial components that influence tumor behavior and treatment response. In this review, we provide a comprehensive overview of the recent advancements in PDO co-culture systems designed to integrate TME elements. Additionally, we emphasize the role of biomedical engineering technologies, such as 3D bioprinting and organoids-on-a-chip, in enhancing the physiological relevance of these models. Furthermore, we explore how bladder PDO co-culture systems are applied in research on bladder CSC characterization, evolution and treatment responses. Finally, we discuss future directions for improving PDO systems to achieve more accurate preclinical modeling and drug discovery.