Using stereologic techniques for podocyte counting in the mouse: shifting the paradigm.

Area of Science:

• Nephrology
• Stereology
• Cell Biology

Background:

• Podocytes are crucial for the glomerular filtration barrier, and their decreased number is linked to proteinuric kidney diseases.
• Existing methods for counting podocytes show significant inconsistencies, hindering accurate research.
• Previous work established the fractionator/disector method as a reliable approximation for exhaustive podocyte counts.

Purpose of the Study:

• To compare the accuracy and efficiency of a design-based approach (fractionator/disector) versus a model-based approach (Weibel-Gomez) for counting podocytes.
• To assess podocyte number and glomerular volume in db/m and db/db mice using both methods.

Main Methods:

• The design-based approach utilized 1-μm-thick toluidine blue-stained sections with the fractionator/disector method.
• The model-based approach involved counting WT-1-immunolabeled podocyte nuclei in 3- to 4-μm-thick sections using the Weibel-Gomez method.
• Glomerular volume was determined for each counting method.

Main Results:

• The fractionator/disector method counted 89 ± 10 podocytes, while the Weibel-Gomez method counted 137 ± 38, overestimating by 54% (p < 0.05).
• Glomerular volume was underestimated by 17% (p < 0.0002) using the model-based approach.
• The model-based approach was also found to be more time-consuming.

Conclusions:

• The fractionator/disector method provides an unbiased and efficient determination of podocyte counts.
• This design-based stereological method is recommended for accurate podocyte enumeration in kidney research.
• Accurate podocyte counting is essential for understanding kidney disease progression.