Relative biodistribution and accumulation of carbonaceous nanoparticles inside the murine and human kidney

• Carbonaceous nanoparticles were detected in all investigated functional renal components, including the glomeruli, proximal tubules, distal tubules, and blood vessels. • The relative distribution of carbonaceous nanoparticles among renal structures was comparable between mouse and kidney tissue, highlighting the translational relevance. • The proximal tubules had the highest relative accumulation of carbonaceous nanoparticles among all investigated renal structures in both mouse and human kidney tissue. . Epidemiological and toxicological studies underscore the adverse health effects of combustion-derived particles, such as carbonaceous nanoparticles (CNPs), which translocate to various organs, including the kidneys. Given the kidneys play a crucial role in filtering toxins, CNP accumulation may pose a risk to renal function. We investigated CNP biodistribution in murine and human kidney tissue to assess potential impacts on kidney health. . In the controlled murine model, wild-type C57BL/6J mice were exposed to CNPs through whole-body exposure. Human kidney tissue was analyzed without prior knowledge of exposure history. CNPs in kidney tissue were detected using femtosecond-pulsed illumination and quantified via a peak-finding algorithm. Renal components – the glomerulus, proximal and distal tubules, and blood vessels – were visualized through immunofluorescence. Colocalization of CNPs with renal structures was quantified using the Just Another Colocalization Plugin. Structural differences were evaluated using Kruskal-Wallis tests. . CNPs were detected in all investigated renal structures of both mouse and human kidneys, providing direct evidence of their translocation. The relative distribution was comparable between species, with no statistically significant differences in colocalization (q > 0.05). The percentages of CNPs in mice vs. humans colocalized with glomeruli (1.46% vs. 1.91%), proximal tubules (13.43% vs. 16.10%), distal tubules (2.72% vs. 3.25%), and blood vessels and capillaries (4.16% vs. 5.21%). . Proximal tubules exhibited the highest relative CNP accumulation in both species. This aligns with research linking environmental pollutants, such as black carbon, to decreased tubular kidney function, suggesting proximal tubule involvement in particle processing.