John Cijan He, MD, PhD, is a Professor of Medicine and Pharmacological Sciences and Chief of the Division of Nephrology at the Icahn School of Medicine at Mount Sinai.

John Cijan He, MD, PhD

Podocyte Injury Emerges as Central Driver of Progression in FSGS, Diabetic Kidney Disease

Podocyte injury plays a central role as the shared mechanism driving proteinuria and progressive kidney dysfunction across both primary and secondary glomerular diseases, including focal segmental glomerulosclerosis (FSGS) and diabetic kidney disease.

Diabetic kidney disease affects approximately 30% to 40% of patients with diabetes, remaining a leading cause of kidney failure worldwide. FSGS accounts for an estimated 20% to 25% of adult nephrotic syndrome cases in the United States.

FSGS and diabetic kidney disease are among the most common glomerular conditions in which podocyte injury plays a central role. In both diseases, progressive podocyte loss is closely associated with worsening proteinuria and declining kidney function, underscoring the importance of these specialized cells in maintaining long-term renal stability.

In these conditions, the overall damage caused by podocyte injury has driven increasing attention toward understanding podocyte biology as both a marker of disease severity and a potential therapeutic target.

“Podocytes form the last barrier of the glomerular filtration system, and they are critical for maintaining that barrier,” John Cijan He, MD, PhD, Professor of Medicine and Pharmacological Sciences and Chief of the Division of Nephrology at the Icahn School of Medicine at Mount Sinai, shared in an interview with HCPLive. “If you lose podocytes, patients can develop proteinuria.”

Podocytes are highly specialized epithelial cells that wrap around glomerular capillaries and form interdigitating foot processes connected by slit diaphragms. They serve as the final selective barrier preventing the passage of proteins into the urine and are essential for maintaining normal glomerular function.

Furthermore, these cells are terminally differentiated, non-proliferating cells, meaning once they are injured or lost, they cannot be regenerated or replaced. This limitation plays a key role in the podocyte depletion hypothesis, which proposes that progressive loss of podocytes directly drives glomerulosclerosis, chronic proteinuria, and ultimately kidney failure.

“Unfortunately, we don’t currently have therapies that can restore podocytes. Another important point is that podocytes can detach or die, but they are what we call quiescent cells—they cannot regenerate or proliferate,” said He. “So, once podocytes are lost, that’s essentially it. The kidney has very limited ability to repair this injury.”

Since the loss of podocytes is irreversible, even modest injury can accumulate and accelerate disease progression over time. As a result, researchers are not only focused on treating the upstream causes of kidney disease, but are also trying to identify strategies to preserve podocyte integrity and slow their loss.

Additionally, He explains the ongoing effort to improve the measurement of podocyte injury. Currently, investigators are exploring new reproducible biomarkers, including urinary markers such as nephrin and other podocyte-associated proteins, to more early identify glomerular injury. Additional approaches include detection of podocyte fragments or intact podocytes shed into the urine, which may reflect ongoing structural damage within the glomerulus.

“Podometrics” is an emerging concept in this space, a method aimed at quantifying podocyte number and density as a way to more directly assess disease progression. Prior research has suggested that podocyte-based measurements may provide a less invasive window into glomerular health and could have utility in conditions beyond FSGS and diabetic kidney disease, including IgA nephropathy.

While proteinuria remains the dominant clinical marker, the field is gradually moving toward earlier and more precise methods of detecting glomerular injury, with the goal of improving risk stratification and enabling earlier intervention.

Pavenstädt H, Kriz W, Kretzler M. Cell biology of the glomerular podocyte. 

https://doi.org/10.1152/physrev.00020.2002

Wiggins RC. The spectrum of podocytopathies: a unifying view of glomerular diseases. 

Puelles VG, Bertram JF. Understanding podocyte depletion in progressive kidney disease. 

https://doi.org/10.1038/s41581-018-0001-7

D’Agati VD, Fogo AB, Bruijn JA, Jennette JC. Pathologic classification of focal segmental glomerulosclerosis. 

https://doi.org/10.1053/j.ajkd.2003.10.024

Alicic RZ, Rooney MT, Tuttle KR. Diabetic kidney disease: challenges, progress, and possibilities. 

Wang G, et al. Urinary nephrin as a biomarker of podocyte injury in kidney disease. 

https://doi.org/10.1016/j.cca.2014.08.020

John Cijan He, MD, PhD

Articles