Bioelectrical Mechanisms for Programming Growth and Form: Taming Physiological Networks for Soft Body Robotics

The design challenge for soft body robotics is the creation of modular, complex, self-repairing, functional constructs. This long-range vision requires moving beyond the synthetic biology of soups of individual cells to the production of multicellular organs of any desired morphology. To achieve predictive control of bioengineered growth and form, we must learn from developing embryos and regenerative model species to understand and exploit the principles that guide large-scale pattern formation and enable self-repair and dynamic reconfiguration of living tissues. Endogenous bioelectrical signaling among cells in vivo is a powerful communication and control system that orchestrates individual cell behavior toward organism-wide anatomical states. All cells, not just excitable nerve and muscle, use voltage gradients to regulate growth and differentiation and to coordinate the activity that drives the formation of entire organs or appendages. Here, we identify exciting opportunities for soft body robotics to exploit the recent developments in this fascinating new field. Work in tractable model systems such as the frog showed that information stored in real-time bioelectrical networks can be manipulated to reprogram cells at the level of organ specification. Remarkably, specific modulation of physiological state can override genetic information and stably alter body pattern or prevent cancerous disorganization. The integration of bioelectric circuits with the metabolic and transcriptional modules used in synthetic biology is also now feasible. We present a toolkit of genetically encoded components that facilitates the inclusion of bioelectrical controls in bioengineering applications for programming the self-assembly of complex structures. Bioelectric manipulation of morphogenetic modules existing within multicellular systems helps avoid the cost of micromanaging the construction of biobots of arbitrary configuration. However, interesting challenges arise because of as-yet poorly understood spontaneous self-organization and emergent order in physiological networks. Together with new optogenetic technology for reading and writing bioelectric information into living constructs, bioelectricity offers the opportunity to guide the self-assembly of computational tissues, with far-reaching applications in soft body robotics, as well as regenerative medicine, cancer biology, cybernetics, and synthetic biology.