FIG. 1.

Schematics of three-dimensional (3D) bioreactor configurations designed to provide cells with (A) perfusion and (B) diffusion conditions under a constant medium feed rate. Cells in configuration (A) were subjected to a constant overall medium recirculation rate of 15 mL/min whereas those in configuration (B) were not exposed to such conditions due to the lack of a recirculation pump. Both reactors received fresh medium at a rate of 2 mL/h (green lines). The constant medium recirculation in (A) exposes cells to counter-directional cross-flow perfusion in the cell compartment whereas cells in (B) are only exposed to a slow, diffusive flow from the medium feed pump. (C) Detail of the bioreactor cell compartment illustrating medium and oxygenation fiber arrangement as well as the principle of medium perfusion in the cell compartment.