(692d) Silk Protein-Based Hydrogels for 3D Printing of Tissue Constructs

Substrate topography, along with mechanical properties and presence of cell-relevant ligands and cues, has been established as a crucial design parameter that affects cellular behavior in in vitro tissue models. Understanding cellular behavior in engineered human tissue is expected to lead to greater physiological relevance of these models, which may ultimately facilitate application of the model for in vitro drug screening or disease modeling. In the small and large intestine, villi and crypts, respectively, are the major morphological features that contribute to tissue function. Recent examples of in vitro tissue models have sought to incorporate crypt topographies more representative of large intestine morphology into culture substrates through different means, including the use of decellularized extracellular matrix, formation of hydrogels around sacrificial components, or casting scaffolds against patterned substrates. While previous work with these models have shown that topography affects cellular response, there are two main limitations with these models: 1) the constructs degrade quickly in many cases, and 2) the topography cannot be easily varied. This research focuses on preparing intestine-like structures by 3D printing silk protein hydrogels. Silk proteins can be enzymatically crosslinked into biocompatible hydrogels with long-term stability and tunable mechanical properties. This work develops a new synthetic approach that enables 3D printing of the enzymatically-crosslinked hydrogels. Rheological experiments were used to determine flow behavior and gelation kinetics, and constructs were then 3D printed using robotic dispensing. Intestinal cell lines were cultured on and within the gels to quantify cell attachment, proliferation, and morphology on the printed constructs.