Engineering erythrocytes into synthetic cells using cell-free gene expression

Erythrocytes, commonly known as red blood cells (RBCs), constitute the most abundant cell type in vertebrate mammals. Due to their unique biological and physical attributes, RBCs have been the focus of extensive research in biomedical engineering. Methods have been developed to transform RBCs into adaptable carriers for molecular payloads, thereby extending their functional capabilities beyond what they naturally transport and accomplish. Concurrently with RBCs applied science, cell-free gene expression (CFE) has advanced into a tractable technology that can be integrated with a broad range of materials. In this work, we harness the advantages of CFE to engineer RBCs into hybrid synthetic cells. We encapsulate CFE reactions within RBC ghosts to execute elementary gene circuits, including biosensors, and to synthesize phages from their genomes. Furthermore, we engineer and functionalize the outer membrane of mature RBCs to attach diverse payloads, such as a SARS-CoV-2 antigen recognized by a specific antibody. CFE interfaces remarkably well with RBCs, enabling their rapid, low-cost transformation into red blood synthetic cells (RBSCs) with potential biomedical and biotechnological applications.