(145g) Programmable Cellular Remodeling of Anisotropic Hydrogels

Highly regulated cellular anisotropy is widely observed in vivo. Yet, capturing tissue anisotropy in vitro is an open challenge, as collective behaviors of cells are typically studied in isotropic settings. While considerable literature exists on engineering cell alignment, limited efforts have been directed toward emulating and predicting morphogenic pathways influenced by anisotropic cell proliferation, force generation, and modifications in the surrounding matrices, in a tightly coupled process. Our lab integrates knowledge and tools from soft matter to engineer functional biological assemblies for tackling this question. In 2D monolayers, we show that flat substrates with orientational order can induce global alignment on a millimeter scale. Remarkably, single cells are not sensitive to the substrate’s anisotropy. Rather, the emergence of global nematic order is a collective phenomenon that requires both steric effects and molecular-scale anisotropy of the substrate. In 3D cell-laden matrices, we demonstrate the fabrication of initially flat, thin, free-standing collagen sheets that can undergo controllable 2D and 3D shape transformations. First, we fabricate hydrogels with fibrin-like morphologies. Next, we embed human dermal fibroblasts in collagen and grow them on pre-ordered hydrogels. Cells align following the anisotropic cues and remodel the collagen. These cell-laden collagen sheets spontaneously contract through the traction force of the encapsulated cells. By programming the orientation of the cells, we can control the macroscopic shape transformation of the matrix. These oriented cell sheets are modular, requiring minimal instrumentation and no special release mechanism, aiding their wide adaptation. Our work establishes the groundwork for generating matrices that can undergo orientationally directed shape transformations, paving the way for the ultimate realization of in vitro morphogenesis.