Local actuation of organoids by magnetic nanoparticles

Tissues take shape during development through a series of morphogenetic movements guided by local cell-scale forces. While current in vitro approaches subjecting tissues to homogenous stresses, it is currently no possible to recapitulate highly local spatially varying forces. Here we develop a method for local actuation of organoids using embedded magnetic nanoparticles. Sequential aggregation of magnetically labelled human pluripotent stem cells followed by actuation by a magnetic field produces localized magnetic clusters within the organoid. These clusters impose local mechanical forces on the surrounding tissue in response to applied global magnetic fields. We show that precise, spatially defined actuation provides short-term mechanical tissue perturbations as well as long-term cytoskeleton remodeling. We demonstrate that local magnetically-driven actuation guides asymmetric growth and proliferation, leading to enhanced patterning in human neural organoids. We show that this approach is applicable to other model systems by observing polarized patterning in paraxial mesoderm organoids upon local magnetic actuation. This versatile approach allows for local, controllable mechanical actuation in multicellular constructs, and is widely applicable to interrogate the role of local mechanotransduction in developmental and disease model systems.