What does 'the body as a bioreactor' mean? In this discussion how scientists use the body's machinery to produce therapeutic proteins. Scott Ripley, General Manager of Nucleic Acids at Cytiva, explains that traditional bioprocessing uses external bioreactors, while the new approach leverages the body's natural processes. This method offers benefits like longer protein half-life and the ability to express multiple proteins simultaneously. Justin Eyquem, assistant professor at University of California San Francisco, discusses the potential of in vivo CAR T cell therapy, which could simplify manufacturing and reduce costs. Both approaches face challenges in quality assurance and regulatory approval but hold promise for personalized and more effective treatments.