Organoid bladders reveal secrets of UTIs

Urinary tract infections (UTIs) are among the most common bacterial infections. They usually require treatment with antibiotics, and almost a quarter of treated cases lead to recurrent infection.

The vast majority of UTIs are caused by a subspecies of the bacterium Escherichia coli, which infect cells that line the bladder wall and form what are known as "intracellular bacterial communities."

"Infection dynamics are difficult to capture from static imaging of tissue explants at serial time points," says Kunal Sharma, the lead author on the two studies. "Thus far, in vitro models have not recapitulated bladder architecture with sufficient fidelity to study the time course of these events."

To address this, the group of Professor John McKinney at EPFL's School of Life Sciences developed two complementary bladder models to study UTIs in a more controlled way. The first model consists of bladder organoids that recreate the 3D stratified architecture of the bladder epithelium. Organoids are tiny lab-grown tissues and organs that are anatomically correct and physiologically functional.

The second model is a bladder-on-a-chip that incorporates physiological stimuli, e.g. the mechanical effect of bladder filling and voiding, as well as an interface with the vasculature to study immune cell migration to sites of infection..