Magnetically actuated cell-laden microscale hydrogels for probing strain-induced cell responses in three dimensions

Micromechanical strain is shown to play a key role in the growth and development of tissue and muscle cells in three-dimensional environments. Feng Xu and co-workers have developed an innovative medium for visualizing and influencing cell growth with biocompatible, water-based hydrogels. Using photolithography, the team fabricated a micrometre-thick, multilayer device in which cell-laden hydrogels sat above a separate hydrogel film infused with magnetic iron nanoparticles. Applying a magnetic field caused the lower hydrogel film to deform homogenously, altering the strain of the three-dimensional cell-growth region by up to 60 per cent. This method has the advantage that it does not use damaging mechanical contacts. The transparent hydrogels enable real-time microscopy imaging of fibroblast and myoblast viability and proliferation under realistic strain conditions — valuable data for artificial muscle applications and pathophysiological studies of injury healing.