Enhanced biocompatibility of 3D printed resin parts via wet autoclave postprocessing: implications for stem cell organ-on-a-chip culture†

3D printed parts made from photocured resins are widely used in surgery, dentistry, medical devices, and organ-on-a-chip research due to their ease of fabrication and customization. However, extensive postprocessing is needed to reduce their cytotoxicity. In this study, we demonstrate that a 60-minute “wet” autoclave process significantly reduces leachates compared to many commonly used postprocessing methods. This reduction in leachates was observed across all four tested resins, indicating the general applicability of this method. Materials marketed as biocompatible did not affect stem cell growth and only had a minor effect on differentiation after a 60-minute wet autoclave treatment, unlike non-wet autoclaved parts, which showed marked effects. We assessed cellular function using morphology, viability assays, functional assays, and metabolomics. While no immediate effects were observed from the tested materials after wet autoclavation, transcriptomic analysis revealed that sub-cytotoxic levels of leachates downregulated extracellular matrix genes and upregulated genes related to cell adhesion and lipid and fatty acid metabolism. These changes could have long-term implications. In conclusion, the wet autoclave protocol described here is an easy-to-implement, standardized postprocessing step that reduces the exposure of organisms to resin leachates from 3D-printed parts.