Light-regulated pro-angiogenic engineered living materials

Abstract

I.Despite their promise, the application of growth factors in regenerative medicine is limited by their poor stability in the body, high costs of production/storage and need for localized and tightly controlled delivery to minimize adverse side effects. In this study, a unique strategy to overcome these limitations is explored based on engineered living materials (ELMs). These are an emerging class of composite materials, which contain live microorganisms that can be engineered to produce and secrete proteins in response to external stimuli. Herein, the development of an ELM that light-responsively releases a pro-angiogenic protein is described. This is achieved by optogenetically engineering bacteria to synthesize and secrete a fusion protein containing a vascular endothelial growth factor peptidomimetic linked to a collagen-binding domain. The bacteria are securely encapsulated in bilayer hydrogel constructs that support bacterial functionality but prevent their escape from the ELM. The possibility to switch protein release ON and OFF with light and to tune the amount released with different light intensities is demonstrated. Finally, it is shown that the released protein is active through its ability to bind to collagen and promote angiogenic network formation in human vascular endothelial cell cultures, indicating the regenerative potential of these ELMs.