Methods and systems for cell bed formation during bioprocessing
Methods and systems are disclosed for manipulating inert materials and biomaterials, including cell cultures, to efficiently form effective cell beds while preventing excess flow through of cells to permeate waste during bioprocessing. Gentle centrifugation concentrates a large volume of cells produced from bioreactors into the desired concentrated volume and cell density. When cells pass through the centrifuge, the majority fraction of cells are retained in the centrifuge disposable chamber pods as a cell bed. A recirculation loop redirects the remaining minority fraction of cells back to the cell bag instead of proceeding to waste. This prevents initial cell loss during cell bed formation in the chamber pods, increases overall cell yields at harvest, and conserves materials, for example. Growing and harvesting natural killer cells, in particular, increased yields by over 30% when the recirculation loop was employed.
1 . A method for enhancing fluidized biomaterial bed formation, the method comprising:
providing a bioprocessing system, the system having a chamber having an inlet and an outlet, a bi-directional pump, a waste bag, a waste line, a recirculation bag/bioreactor, and a harvest vessel fluidly connected together; wherein (i) the waste line connects the waste bag and the chamber via the chamber outlet, and (ii) the bi-directional pump connects the recirculation bag/bioreactor and the harvest vessel to the chamber via the chamber inlet;
attaching a recirculation loop from the waste line to the recirculation bag/bioreactor, the recirculation loop having a sterile tube attached to a valve;
providing a media and a biomaterial to the system;
activating the system such that during at least an initial process, the media and biomaterial in the chamber return to the recirculation bag/bioreactor when the valve is in a first position, thereby recirculating the media and biomaterial from the chamber back to the recirculation bag/bioreactor via the recirculation loop instead of the waste bag;
removing a minority fraction of the media and the biomaterial from the chamber to the waste line when the valve is in a second position, thereby directing the minority fraction of the media and the biomaterial from the chamber into the waste bag instead of the recirculation bag/bioreactor;
collecting a majority fraction of the biomaterial from the recirculation bag/bioreactor into the chamber via the bi-directional pump; and
collecting the majority fraction of the biomaterial from the chamber into the harvest vessel via the bi-directional pump; and
wherein the recirculation of media and biomaterial from the chamber back to the recirculation bag/bioreactor via the recirculation loop increases collection yield of the majority fraction of the biomaterial in the chamber by 25% to 32% as compared to a method without recirculation, and
wherein about 86% of the majority fraction of biomaterial is collected into the harvest vessel.
2 . The method of claim 1 , further comprising:
disposing a sterile septum port along the recirculation loop, the port configured to allow a permeate to be sampled and monitored for biomaterial flow through titers.
3 . The method of claim 2 , wherein the minority fraction of media and biomaterial is removed to the waste line when the titers indicate a biomaterial density in the recirculation loop of less than about 1×10 5 cells/mL.
4 . The method of claim 1 , wherein the biomaterial is cells, cellular organelles, nanoparticles, micro-particles, cellular products, antibodies or antigens.
5 . The method of claim 4 , wherein the cells are NK cells, aNK cells, NK cells engineered to express an Fc receptor, NK cells engineered to express a chimeric antigen receptor, NK cells engineered to express an Fc receptor and a chimeric antigen receptor or variants thereof.
6 . The method of claim 1 , wherein the bioprocessing system is a continuous centrifugation system.