Kidney tissue grown from induced stem cells

Engineered human cells that can give rise to every cell type have been induced to generate structures that resemble an embryonic kidney. This advance charts a course towards growing transplantable kidneys in culture. See Letter p.564 The development of the human kidney in the embryo depends on two different stem cell types, one to generate collecting ducts and the other to generate functional nephrons. Melissa Little, Minoru Takasato and colleagues showed previously that human pluripotent stem cells (hPSCs) can differentiate into both types of progenitors. They have now identified the signalling conditions required to induce not only these structures but also the surrounding cell types including interstitium and blood vessels. Using this approach, they have grown kidney organoids that recapitulate the functional regionalization of the embryonic kidney. The tissue complexity and degree of functionalization achieved in these organoids are not on a par with a working kidney, but replicate the normal human embryonic kidney. Importantly, they provide evidence of their potential in screening drugs for toxicity, modelling genetic kidney disease or perhaps to provide specific kidney cell types for cellular therapy.