Generic optimization procedure for high-resolution printing by stereolithography of 3D scaffolds compatible for cell culture applied to a small intestinal architecture.

Abstract

Stereolithography is now widely used in tissue engineering since it allows fine-tuning of geometry and mechanical properties to mimic the topography of tissues. However, most published studies do not detail the optimization protocols that have been used to obtain these structures. Here, we developed a generic process to print photosensitive biomaterial formulations by stereolithography to obtain a specific topography. Using the small intestine architecture as a model combining filled villi and hollow crypts, we identify key parameters that govern both printing resolution and cellular behavior. Moreover, we highlight the impact of absence of oxygen inhibition and light penetration depth in cavities, causing partially crosslinked material within crypts. This issue was resolved by adding tartrazine, a biocompatible photoabsorber that restricts crosslinking depth. Our stereolithography (SLA) process allows the fabrication of intestinal models with a high precision level and the reproduction of crypt and villi structures with physiologic dimensions and high structural integrity. We show that Caco-2 cells adhere, colonize, polarize and differentiate on the printed scaffolds over 20 days of culture. The developed models could subsequently be adapted to support intestinal organoid growth and be integrated in microfluidic chips to implement mechanical and biochemical cues, representing a more physiological model with accurate dimensions to study intestinal diseases.Overall, this study provides a transferable framework for optimizing stereolithographic printing of hydrogel-based topographies allowing precise control of substrate properties for tissue engineering.