Project Summary Hydrogels are widely used in tissue engineering and regenerative medicine due to their ability to mimic the physical properties of various tissues, host encapsulated cells, and serve as models for diseased and traumatized tissue. Despite these advantages, they face many limitations that hinder their utility and impede their adoption. A primary limitation is their inability to support cell motility and proliferation, the elaboration of extracellular matrix (ECM) components, and the development of de novo tissue. These limitations are primarily attributed to a lack of hierarchical structure bridging the macromolecular and tissue length scales. Conventional, homogeneous polymeric hydrogels, for instance, lack long range architectural features, such as micron-scale porosity. Recently, granular hydrogel scaffolds, a new class of materials composed of densely-packed hydrogel microparticles, has been introduced and rapidly adopted. These scaffolds offer many advantages over conventional hydrogels for tissue engineering. Leveraging advances in high- throughput microfluidic emulsion templating, hydrogel particles can be produced in sufficiently large quantities to enable the assembly of macroscale materials. These granular scaffolds offer significantly increased porosity, facilitating the infiltration of cells and the rapid diffusional exchange of nutrients and waste products. Moreover, particles can be designed independently of macroscale requirements, effectively decoupling material stiffness from porosity. Beyond these design advantages, granular scaffolds can be injected, 3D printed, or molded into arbitrary shapes. This proposal seeks to extend the known advantages of granular gels by incorporating newly developed microfabrication capabilities. The Oakey lab has recently demonstrated the ability to fabricate heterogeneous particles with network architecture sculpted on the nanoscale. This capability offers several unique advantages including tunable rheological properties, controlled degradation, and quantitatively tailored biofunctional interfaces. We will use these capabilities to produce granular scaffolds as a medium to study fundamental and poorly understood questions of cell motility and proliferation within granular scaffolds. This knowledge will then be applied to develop translational applications for granular scaffolds in cartilage regeneration and peripheral nerve allografts. Our interdisciplinary team of researchers have a track record of productive research collaboration and mentoring and each investigator provides a specific and complementary expertise that will inform the rapid acceleration of granular scaffold development. The overlapping aims and activities between all projects will ensure that the findings from each project inform the others. The Specific Aims of this collaborative team project, described as a co-project and led by one investigator, are: co-Project 1: To microfabricate hydrogel particles, cell carrie...