Serial propagation of mammalian cells on microcarriers

For the large‐scale operation of microcarrier culture to be successful, a technically feasible method for sequential inoculation is essential. Using human foreskin fibroblasts, FS‐4, we have achieved this by detaching cells viably from microcarriers employing a selection pH trypsinization technique. Cells thus detached are able to reattach to microcarriers and grow normally after subsequent reinoculation into new cultures. However, after reinoculation cells attach to new microcarriers at a higher rate than to used microcarriers on which cells have previously grown. The effect of this differential cell attachment was analyzed and overcome by employing a low inoculum concentration. FS‐4 cells could thus be serially propagated on microcarriers and subsequently used for β‐interferon production. This technique has also been applied to the cultivation of a monkey kidney cell line, Vero. We have also shown that Vero cells directly inoculated from a seed microcarrier culture could be used for virus production.