What if the road to an artificial kidney starts with a cell that simply refuses to burn out in the lab? Researchers at the University of Southern California say they have taken an important step by creating long-lasting nephron progenitor cells, the early kidney cells that build nephrons, and using them to form kidney organoids.
This does not mean transplant-ready lab kidneys are suddenly around the corner. But it does mean scientists now have a sturdier, more scalable way to grow the cells behind the kidney’s filtration system, study genetic disorders, and test potential drugs with more precision than before.
Why this matters for kidney disease
Each kidney contains about a million nephrons that filter blood, remove wastes, and help balance water and minerals. That microscopic work is easy to ignore until it fails, yet chronic kidney disease affects more than 1 in 7 U.S. adults, and 94,015 people were on the U.S. kidney waiting list as of December 1, 2025.
That is why this USC result matters beyond the lab bench. Nephron progenitor cells are the starter material for building nephrons, and when researchers can grow them reliably, they can turn them into organoids (mini 3D kidney structures) for studying development, disease, and possible treatments.
How the team kept these cells growing
To pull this off, the researchers adjusted signaling around two proteins called p38 and YAP, which act a bit like internal switches that influence whether cells keep a flexible, progenitor-like state. The result was long-term clonal expansion of mouse and human nephron progenitor cells, including induced versions made from human pluripotent stem cells.
The new culture setup also simplified the workflow. USC says the improved cocktail supports growth in a basic 2D format rather than a more cumbersome 3D system, and the induced cells can be created from a simple blood or skin biopsy, which opens the door to patient-specific disease models.
“By enhancing our capability to grow NPCs from human stem cells, we create a new avenue for understanding and combating congenital kidney diseases and cancer,” said lead author Zhongwei Li. That sounds technical, but in practical terms it means researchers can keep a better supply of kidney-building cells on hand instead of starting from scratch every time.
What made the organoids stand out
Kidney organoids are useful, but for the most part they have had a messy problem. Many published protocols generate unwanted “off-target” cells, including neurons and muscle-like cells, but the USC team reported organoids with minimal off-target cell types and, in one single-cell-style analysis, just 0.67% off-target cells.
The organoids also showed stronger maturation of podocytes, the specialized cells that help filter blood inside the nephron. And then came the surprise. The culture medium could even push mature podocytes back toward an NPC-like state, revealing a form of kidney cell plasticity that researchers did not fully appreciate before.
Why this could speed up drug discovery
Because the cells grew longer and were easier to edit, the team could use them for genome-wide CRISPR screening. That helped uncover genes tied to kidney development and disease, including some already suspected and some new candidates, which is exactly the kind of platform researchers need when they are trying to understand how a disorder begins.
The same platform also modeled autosomal dominant polycystic kidney disease (ADPKD), the most common inherited kidney disease, and let the scientists screen 148 compounds for their effects on cyst formation. Fourteen compounds showed significant inhibition in at least one screen, 12 held up in a second round, and PTC-209 stood out as a dose-dependent inhibitor that had not previously been linked to suppressing ADPKD cysts.
Why this is promising but not the final answer
Here is the part worth keeping in mind. These are still organoids and lab-grown cell systems, not full artificial kidneys ready for transplant, and the authors note there is still a lot of work to do to generate the full range of nephron cell types, especially structures such as the loops of Henle and distal convoluted tubules.
Still, this advance feels important because it addresses a basic problem in regenerative kidney research: getting enough reliable kidney-building cells to study and edit. For people facing long transplant waits and the uncertainty that comes with kidney failure, that kind of progress is not abstract at all.
The study was published in Cell Stem Cell.
