. Our established protocol allowed these cells, at a cell seeding of 2 × 1E5 cells/microfiber carriers (MC) (3.5 × 1E6 cells/mL; 1.7 × 1E4 cells/cm2), to grow inside a 4 m2/200 mL fixed-bed attaining a concentration of 5.3 × 1E6 cells/MC (9.5 × 1E7 cells/mL; 4.7 × 1E5 cells/cm2) for S2 cells or 4.6 × 1E6 cells/MC (8 × 1E7 cells/mL; 4.1 × 1E5 cells/cm2) for Sf9 cells.