U of T researchers show that fractal geometry can help kidney cells grow in a more mature form

Researchers at the Institute of Biomedical Engineering at the University of Toronto have developed a new way to grow specialized kidney cells in the lab so that they look and behave more like they do in the body.  

By placing the cells on surfaces patterned with fractal shapes that mimic natural structures in the kidney, the team encouraged the cells to develop a more mature and branched form. This advance may improve laboratory models of kidney disease and support safer and more accurate drug testing. 

These findings were published in a recent issue of Nature Communications. The study was led by first author and PhD student Mary Chuan Liu, with Professor Milica Radisic as corresponding author. 

The kidney filters waste from the blood while keeping important proteins, a task that depends on podocytes, highly branched cells in the glomerulus. When podocytes lose this branching structure, kidney function declines.  

Growing mature podocytes in the lab has been difficult, because cells on flat culture surfaces usually stay immature. Fractal patterns, which repeat at different scales like snowflakes or tree branches, are common in biology, but their role in cell maturation is not well understood in the kidney.  

The researchers asked whether recreating fractal geometry in lab-grown environments could help podocytes develop their natural form, addressing a major gap in current kidney cell culture systems. 

The researchers first showed that the kidney’s filtering units and podocyte cells naturally have fractal, branching patterns, and that this complexity is reduced in disease. By using tissue images as reference, they designed similar fractal shapes on lab-made surfaces, then grew podocyte cells on either flat surfaces or these fractal-patterned ones. 

In the long term, this work suggests that geometry itself can be used as a design tool to guide how cells grow and mature. More realistic lab-grown podocytes could improve disease modeling, help scientists study drug toxicity, and contribute to the development of better treatment strategies.