3D fractal topography attenuates inflammation and confers resilience to glomerular podocytes

This study engineered glomerulus-scale 3D fractal hemispheres (≈200 µm diameter, ≈100 µm height) fabricated via Nanoscribe two-photon polymerization in a flexible IP-PDMS resin to model how physiologically inspired surface fractality regulates human podocyte maturation and inflammatory resilience. Across smooth to increasingly complex fractal indices, intermediate fractality promoted podocyte cytoskeletal branching/orientation, increased slit diaphragm marker nephrin, and elevated ECM-associated markers (e.g., collagen IV), consistent with enhanced maturation. Transcriptomic profiling showed that podocytes on intermediate fractal substrates upregulated nephrogenesis-related programs while suppressing inflammatory and kidney disease–associated pathways (including TNF, IL-17, p53, FoxO, and PI3K-Akt signaling), with supportive cytokine profiling in conditioned media. Under inflammatory challenge with TNF-α and IL-6, podocytes cultured on fractal hemispheres—especially intermediate fractality—exhibited reduced cytokine-induced morphological injury and better maintenance of nephrin localization relative to smooth controls. In Transwell co-culture with THP-1 reporter macrophages, podocytes conditioned on fractal substrates attenuated macrophage inflammatory signaling, reducing NF-κB and IRF activation compared with smooth-surface podocyte conditioning. Overall, the work establishes fractal topography as a tunable biophysical cue that improves podocyte phenotypic stability and dampens inflammatory crosstalk, providing a more physiologically relevant in vitro platform for studying inflammatory kidney disease mechanisms.