Selection and isolation of cells for optimal growth in hollow fiber bioreactors

Growth of a murine hybridoma in a hollow fiber microbioreactor was poor. Th is corresponded to slow initial growth in the Maximizer, a pilot scale holl ow fiber bioreactor system. Medium screening experiments with the microbior eactor demonstrated that the slow growth was due to dialysis of low molecul ar weight serum components (under about 10 kDa) from the cell side of the f ibers to the basal medium on the noncell side of the fibers. Better growth can be achieved by adding serum to both sides of the fibers, but this is an expensive option. As an alternative, the microbioreactor was used to selec t for a population of cells that did not require serum on both sides of the fiber for optimal growth. From this population, a stable subclone was isol ated using limiting dilution followed by growth assessment in microbioreact ors. The subclone was cultured in the Maximizer under conditions identical to the parental cell line. The subclone reached confluency in about 9 days compared with about 16 days for the parental cell line. At confluency, the subclone produced antibody at twice the rate of the parental cell line. The se results demonstrate that the microbioreactor is a useful tool for quickl y isolating subclones that are better suited for growth in a hollow fiber b ioreactor.