Hierarchically Curved Gelatin for 3D Biomimetic Cell Culture

The stiffness, microcurvature, and meso-curvature of cellular microenvironments can significantly alter cell and tissue function. However, it is challenging to produce in vitro tissue models that feature tunability in shape, stiffness, and curvature simultaneously in a high-throughput and costeffective manner. One of the significant challenges is the fragility of micropatterns in soft and biocompatible hydrogels. Here, we describe an approach that combines reflow photolithography, soft lithography, and strain engineering to create soft anatomically mimetic gelatin cell culture models. The models can be mechanically tuned to have stiffnesses as low as 400 Pa to as high as 50 kPa featuring hierarchical curvature at two length scales: the cellular length scale of 12 to 120 mu m, and the mesoscale of 1-4 mm. We characterize the microstructured gels using optical microscopy and rheometry, highlighting tunability in the hierarchical curvature, modulus, and shape. Also, collagenbased gelatin offers high-level biocompatibility and bypasses the need for additional surface modification to enhance cell adhesion. We anticipate that this approach could advance anatomically accurate in vitro 3D cell culture models of relevance to biofabrication, cell biology, and drug screening.