Kidney organoids are masses of kidney cells grown in a lab for medical and research purposes to mimic kidney functions. With further development, doctors could use kidney organoids and engineered tissues in transplant settings to replace the need for human donors. A major roadblock in this technology is achieving enough differentiated nephrons (functional cells) to allow the organoid to act as a functioning kidney. Normally in kidney development, multiple rounds of nephron differentiation result in hundreds of nephrons. However, organoids currently undergo only one round of differentiation, limiting their current usefulness for research and medicine. 

The inventors noted that, in normal kidney development, the growth and branching of the developing ureter tubes apply pressure to the organ's cells in cyclic rounds, and this pressure is required to differentiate them into nephrons. Therefore, the inventors developed a method to mimic these rounds of cellular tension to increase the number of differentiated nephrons in the organoid. 

The inventors identified the crucial role of cellular tension in nephron development in vivo. By adding inhibitors that block the cell's ability to sense tension, the inventors mimic these cyclical tension changes to generate kidney organoids with increased numbers of differentiating nephrons. Using these inhibitors, the inventors see a 2-10 times increase in differentiating nephron cells in kidney organoids. 

• ROCK inhibition yields kidney organoids that have 2-10 times higher levels of LHX1 (a nephron marker) and two times higher levels of Six2 (a marker of cells transitioning into nephrons) than organoids grown without manipulation of cellular tension.
• Non-muscle myosin inhibition yields kidney organoids with two times higher levels of LHX1 than organoids grown without manipulation of cellular tension.
• Both ROCK and non-muscle myosin inhibitors are commonly used and accessible reagents allowing easy adoption into culturing protocols.