Figure 4
Comparison of diluted and perfused cultures when the effects of diffusion are considered. (a) Effect of flow rate Q on the average concentration of transforming growth factor beta (TGF-β) at the bottom of a perfused 24-well-plate well of initial media height h 0 = 5 mm (corresponding to 1 ml culture). (b) Comparison of fed-batch and perfusion strategies with Q = 1 ml/day. The diffusivity is D = 6.5 × 10−11 m2/second, the cell population is assumed constant at X = 105, and the secretion rate is r ϕ  = 1.94 × 10−6 pg/cell/day. Solid black line is the limiting static case for both strategies with no dilution/perfusion (Q = 0 ml/day). The perfused cultures are governed by Equations (5), (12) and (13) in Additional file 1, and the fed-batch cultures by Equations (10) and (11) in Additional file 1.