Q&A

Highlights from an interview with Dr. Jonathan Himmelfarb, an expert in kidney health based at Mount Sinai in New York City.

Originally covered in a feature on reducing chronic kidney disease.

NIHNiH: How do conditions like diabetes, obesity, or heart disease contribute to kidney problems?

Himmelfarb: Because the kidneys are constantly filtering blood, they're exposed to everything in circulation — including harmful substances.

In diabetes, elevated blood sugar levels and altered fat concentrations, along with other metabolic shifts, place added stress on the kidneys. These constant demands over years — typically 10 to 15 — can cause lasting damage, sometimes leading to kidney failure.

Obesity can affect the kidneys similarly, even without high blood sugar. It brings about its own changes in metabolism that can harm kidney function as well.

High blood pressure is another key risk factor. Since the kidneys are rich in blood vessels, increased pressure can strain and eventually damage those vessels, affecting kidney health.

NIHNiH: Why is it important to create more customized treatment strategies for chronic kidney disease?

Himmelfarb: Chronic kidney disease is really more of a condition characterized by impaired kidney function than a single illness. What's considered chronic kidney disease involves one or more of the kidneys’ key roles being compromised, whether it's filtering waste or retaining vital proteins in the blood.

There are many potential causes for this loss of function. Even among individuals with similar risk factors, like diabetes or obesity, kidney damage can present differently.

Different types of cells within the kidney may respond differently to injury depending on the cause, the cells involved, and a person's genetics.

We're now entering a promising phase with new treatments for chronic kidney disease. For example, two people with both diabetes and kidney disease might react differently to the same medication — one may improve, while the other’s condition may continue to worsen.

Currently, we lack the ability to predict these outcomes in advance. The goal of the Kidney Precision Medicine Project is to help healthcare professionals choose the most suitable medication or treatment combination right from the start instead of relying on trial and error.

NIHNiH: Your research includes developing "kidney-on-a-chip" technology using human cells. How could that be more beneficial than using animals for testing treatments?

Himmelfarb: Although animal research has led to breakthroughs, the results often don't carry over effectively to humans. Many treatments that succeed in animals fail in human clinical trials because they’re either unsafe or ineffective.

By using models made from human cells from the beginning, we can potentially speed up drug development and make treatments more effective not only for kidney disease but for other conditions as well.

These organ-on-a-chip systems also allow us to consider genetic differences between individuals. Such differences may impact how a person responds to medicine or even their likelihood of developing disease in the first place.