Kidney Week

Abstract: TH-PO940

Age-Related Changes in Nephrons and Podocytes: A Morphometric Study of Japanese Autopsy Kidneys

Session Information

• Geriatric Nephrology: Innovations and Insights
  October 24, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Geriatric Nephrology

• 1300 Geriatric Nephrology

Authors

• Kubo, Eisuke, Tokyo Jikeikai Ika Daigaku, Minato-ku, Tokyo, Japan

Eisuke Kubo, MD

• Haruhara, Kotaro, Tokyo Jikeikai Ika Daigaku, Minato-ku, Tokyo, Japan

Kotaro Haruhara, MD, PhD

• Sasaki, Takaya, Tokyo Jikeikai Ika Daigaku, Minato-ku, Tokyo, Japan

Takaya Sasaki, MD

• Okabayashi, Yusuke, Tokyo Jikeikai Ika Daigaku, Minato-ku, Tokyo, Japan

Yusuke Okabayashi, MD, PhD

• Kanzaki, Go, Tokyo Jikeikai Ika Daigaku, Minato-ku, Tokyo, Japan

Go Kanzaki, MD, PhD

• Bertram, John F., Monash University, Melbourne, Victoria, Australia

John F. Bertram, PhD, FASN

• Shimizu, Akira, Nihon Ika Daigaku, Bunkyo-ku, Tokyo, Japan

Akira Shimizu, MD, PhD

• Tsuboi, Nobuo, Tokyo Jikeikai Ika Daigaku, Minato-ku, Tokyo, Japan

Nobuo Tsuboi, MD, PhD, FASN

• Yokoo, Takashi, Tokyo Jikeikai Ika Daigaku, Minato-ku, Tokyo, Japan

Takashi Yokoo, MD, PhD

Background

Glomerular filtration rate (GFR) declines with age. However, how the number and size of nephrons and podocytes changes with age or age-related GFR decline is not fully elucidated.

Methods

Fifty autopsy kidneys without apparent kidney disease were studied. Subject age ranged from 28 to 85 years. The total number of non-sclerotic glomeruli (NSG) per kidney was estimated using design-based stereology. Podocyte number per glomerulus and glomerular and podocyte volumes were estimated using model-based stereology. Correlations between these parameters, age and estimated GFR without adjustment for body surface area (eGFR) were assessed using linear regression analysis.

Results

The median number of NSG was 421,547 per kidney and median podocyte number per glomerulus was 492. The loss of NSG averaged 9,040 per year (Fig A), and the total number of podocytes per kidney declined at a rate of 5.57 million per year (Fig B). Given that an average of 9,040 NSG were lost each year, the glomerulosclerosis-associated podocyte loss was estimated as a median of 4.4 million (IQR, 3.5×106–5.0×106) per kidney per year. The number of podocytes lost in each NSG per year was 2.7 (median, IQR 1.2–6.8). Both the number of NSG and total podocyte number per kidney were positively correlated with eGFR. Interestingly, despite the fact that both glomerular and podocyte numbers decreased with aging or eGFR decline, neither glomerular volume nor podocyte volume changed with age (Fig C and D) or eGFR.

Conclusion

This study is the first to quantitatively estimate nephron and podocyte morphometric indices associated with age and age-related GFR decline in the same population. These results suggest that a reduced number of nephrons and podocytes, and a lack of size compensation for these decreases, are characteristic morphological features of aging kidneys.