Engineering Synthetically Programmed Cells for Activation with Orthogonal and Native Ligands for Regenerative Medicine

Abstract

In the field of regenerative medicine, engineered cell therapies are increasingly utilized as a tool for programmed responses to environmental factors, such as growth factors and inflammatory cytokines. These therapeutic cells can be engineered with custom sensing and responding modules for rewiring native cell behaviors. Despite recent advances with synthetic receptors, however, researchers have still struggled to reliably direct therapeutic cell responses. Here, we present innovations in engineering synthetic receptors to respond to monomeric and multimeric orthogonal and native ligands. We first developed a method for activating cells with monomeric orthogonal ligands using an engineered polyethylene glycol (PEG) biomaterial surface. This system allowed for spatial control and directed therapeutic responses, such as inflammation attenuation and neuronal differentiation. We next extended this system to synthetically program cells for activation with multimeric native ligands that are implicated in disease states like Parkinson’s disease, fibrosis, and rheumatoid arthritis. We successfully engineered cells with synthetic receptors for the native ligands TNF-α, TGF-β1, and VEGF and demonstrated significant reporter activation. We then focused on the synthetic receptor for TNF-α in a specific therapeutic application. Parkinson’s disease is caused by the death of midbrain dopaminergic (mDa) neurons, and one recent approach is transplanting these vital cells into patients. However, many mDa neurons die soon after transplantation due to exposure to the pro-inflammatory cytokine TNF-α. To address this, we successfully engineered mDa progenitors with TNF-sensitive synthetic receptors and showed reporter and therapeutic outputs, such as production of the TNF antagonist, soluble TNF receptor 1 (sTNFR1). To our knowledge, this represents the first productive attempt to engineer mDa progenitors with synthetic receptors. Our approach for synthetically programming cells allows for modular receptor domains and transgenes, meaning our system is adaptable for a variety of orthogonal and native ligands and applicable for a range of disease states. In addition, our system allows for precise, user-defined outputs, opening new avenues for reproducible control of engineered therapeutic cell responses.