Engineering Structured Muscle Organoids with FRESH 3D Bioprinting

Organoids have emerged as a powerful way to leverage cell-mediated self-assembly to form relatively complex, organ-like structures for in vitro studies. However, the size and complexity of organoids is often heterogeneous and variable due to a lack of spatial cues that help drive self-organization, ultimately limiting the potential to reproduce the functional repertoire of model tissues. Organoids often assume a spherical shape as the lowest energy state, primarily driven by cell compaction forces. Small variation in internal spatial patterning and cell organization leads to a large amount of heterogeneity between aggregates. To achieve more consistent and complex organoid structure and function, it is necessary to guide formation by tuning the magnitude and direction of compaction forces. Here I have hypothesized that an internal 3D extracellular matrix (ECM) scaffold could provide resistance to cellular compaction, as well as cell-ECM binding sites to control geometry. Tissue construct geometry has been shown to be critical for cellular organization within organoids. Using freeform reversible embedding of suspended hydrogels (FRESH), I designed internal structural scaffolds to guide cellular alignment and introduce vasculature-like features in cell aggregates termed “engineered organoids.” The resulting engineered organoids can serve as a better tissue model for a variety of applications for drug discovery, personalized medicine, or as a tissue building block in regenerative medicine.