Microcontact printing of tissue precursors via geometrically patterned shape-changing hydrogel stamps preserves cell viability and organization

In vitro fabrication of tissues is sought for developing platforms to screen candidate drugs and study tissue morphogenesis, and ultimately to regenerate damaged organs. In this study, a modified microcontact printing technique with patterned shape-shifting poly(N-isopropylacrylamide) hydrogels was used to print organized 3T3 fibroblast tissue precursors to target surfaces coated with either fibronectin, collagen type I or poly-l-lysine. The patterned hydrogels directed cell-organization on the stamp, and a subsequent shape-shift of the hydrogel triggered instantaneous release of the tissue precursor from the stamp. It was observed that post printing, the tissue precursors underwent rapid repolarization with the emergence of focal adhesion complexes on a time-scale much faster compared to cells seeded by standard sedimentation. Moreover, a minimum stamp pressure was necessary for transfer, however, at stamp pressures above approximately 1 psi, cell viability was strongly compromised. To demonstrate the ability to print other cell types using this transfer printing technique, skeletal myoblast tissue precursors were also printed. These results suggest that tissue modules can be organized and transferred with intact pre-patterned morphologies from shape-changing hydrogel structures using a microcontact printing technique. This approach may enable the bottom-up construction of high cell density, scaffold-free tissues with programmed configuration down to the individual cell level.