Ready to use gamma irradiated microcarriers for virus production in single use bioreactor systems

Since the 80´s, microcarriers have been used to provide growth support for adherent cells in vaccine biomanufacturing processes at scales up to 6000 L. Today, as yields are increasing, most newly developed vaccines are manufactured at smaller scales, making single-use technologies suitable. Since many anchorage dependent cell lines grown on microcarriers are sensitive to shear stress, some of the remaining challenges are to have homogenous well-suspended microcarriers and efficient oxygenation of the medium. These prerequisites can limit operating conditions and volumes of the bioreactor process. We show that by carefully selecting operating parameters, good cell growth and virus yields can be achieved in a single-use bioreactor system. Furthermore, the time consuming process of preparation and sterilization of the microcarriers prior to culture can be simplified significantly by using Cytodex™ Gamma. In this study we describe different approaches for the cultivation of Vero cells to high cell densities using Cytodex and/or Cytodex Gamma microcarriers in serum-free medium using ReadyToProcess WAVE™ 25 and/or Xcellerex™ XDR-10 single-use bioreactor system. Vero cells were grown in the bioreactors and infected with influenza virus during exponential growth phase. The concentration of infectious virus was determined by 50% tissue culture infective dose measurement (TCID50). Viral titers of 107 or higher were observed in all cultures. No significant differences in cell growth were observed between the different Cytodex microcarriers, and similar cell concentrations were reached in both bioreactor systems. Our results offer valuable information to facilitate design-in of single-use bioreactor systems and ready-to-use Cytodex Gamma microcarriers, enabling flexible future vaccine productions at smaller scales