Study of Alternating Tangential Flow filtration for perfusion and harvest in Chinese Hamster Ovary cells cultivation

• Perfusion is a mode of operation where a continuous replacement of the conditioned medium by fresh medium is operated. It has the advantage of allowing high cell densities. This mode of operations is also required for some instable proteins since the cell-free supernatant containing the product of interest is immediately stored at low temperature where the proteolysis is not active. The ATF filtration device, Alternating Tangential Flow, has been designed to perfuse mammalian cell cultivation process and is used (or studied) nowadays for applications like perfusion, medium renewal, harvest, etc. The cell broth circulation back and forward in the filter prevents the filter clogging and the design ensures a low shear not damageable for the cells. A perfusion process operated by ATF filtration and using CHO cells producing a monoclonal antibody was developed in a 2 L bioreactor. The medium did not contain animal derived components. Cell densities above 40 x 106 cells/mL were obtained with a perfusion rate of 2 reactor volume/day. The highest cell density observed was 48 x 106 cells/mL. These high cell densities were challenging for the aeration. Pure oxygen aeration by large bubbles from an open tube resulted in satisfying oxygenation until 25 to 30 x 106 cells/mL but became limiting at higher cell densities due to the low kLa of these bubbles and the small liquid height. At higher cell densities, a porous sparger with pure oxygen was used either alone or in combination with the open tube aeration. Automatic delivery of antifoam C and pluronic counteracted the effect of small bubble foam deleterious for the cells. From an operation point-of-view, the perfusion operated by the ATF device was satisfying, without filter fouling, easy to operate and to adjust in comparison with other separation devices by filtration or acceleration.   Finally harvesting by ATF filtration was evaluated in comparison with ‘one-way’ tangential flow filtration, TFF, on an IgG producing CHO fed-batch process produced in 2 L bioreactor. In both operation modes, ATF and TFF, filter fouling occurred after several minutes and the total process time was comparable but an important difference was that the viability drop obtained when using ATF was 15 % while it was 45 % using the TFF.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinsk bioteknologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Medical Biotechnology (hsv//eng)

Nyckelord

ATF

perfusion

CHO cells

hollow fiber filter

SRA - Molecular Bioscience

SRA - Molekylär biovetenskap

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)