Passage Bio and Simcenter M-Star explore gene therapy’s potential using recombinant adeno-associated virus (rAAV) and highlights gaps in manufacturing processes. Utilizing computational fluid dynamics, the study validates operating conditions for a predictive iCELLis® 500 scale-down model, addressing challenges in achieving consistent agitation rates and oxygen transfer across scales. Experimental validation confirms the efficacy of the novel scale-down model, offering insights crucial for optimizing rAAV manufacturing using fixed bed bioreactors.