(758b) Biomaterials That Enable and Drive Scaffold-Free Tissue Formation

Scaffold-free cultures of cells can mimic immature condensates that initiate many developmental and healing processes. Providing specific soluble signals, such as growth factors, exogenously in tissue culture media to regulate cell behavior and promote new tissue formation may be limited by transport issues, lack of spatial control over signal presentation, and required repeated dosing. The first part of this talk will be a report on systems that incorporate biomaterial microparticles containing bioactive signals within scaffold-free cell cultures, permitting localized spatiotemporal control over the presentation of these regulatory cues to the cells to engineer a variety of tissues. Three-dimensional bioprinting has been pursued as a method of building functional scaffold-free tissue constructs with sophisticated geometries without an intervening scaffold that can interfere with critical cell-cell interactions. However, to date it has not been possible to print individual cells directly, as preculturing was required to first form cell aggregates or strands prior to printing. The latter part of this talk will cover the first bioprinting platform using single cells alone, without a macromer solution, as bioink that can maintain printed geometries. A shear-thinning and self-healing biomaterial support bath was engineered to permit high-resolution printing into precise geometries, maintenance of cell viability, cellular condensation formation and long-term culture of constructs for development of engineered tissues. Collectively, these platforms may advance cellular condensation-based regenerative medicine strategies, enhance drug-screening capabilities and provide new tools for addressing questions in developmental biology.