The development of robust, scalable, cost-effective processes that yield high titers of high-quality viral vectors is crucial to the successful commercialization of safe and efficacious gene therapies that require large and/or multiple doses to treat more prevalent diseases. The successful commercialization of viral vector-based therapies relies on GMP-compliant and scalable, industrialized production platforms to rapidly advance high-quality products to market while also ensuring patient safety. The most utilized approach to AAV (adeno-associated virus) and lentivirus (LV) production is through the transient transfection of mammalian cell lines, such as HEK293 or derivatives, followed by viral vector harvest, downstream purification processes and analytics for final product testing. Since viral vector production is a significant cost driver in AAV and LV-based gene therapies, it is prudent to optimize each step of the upstream manufacturing process already at the process development phase to ensure compliance of critical raw materials (eg. plasmid DNA, transfection reagents), maximize yield and product quality while minimizing costs.