Coating a bioreactor in a cell expansion system
Embodiments described herein generally provide for the expansion of cells in a cell expansion system using an active promotion of a coating agent(s) to a cell growth surface in some embodiments. A coating agent may be applied to a surface, such as the cell growth surface of a hollow fiber in a bioreactor, by controlling the movement of a fluid in which a coating agent is suspended, by changing flow rates, by changing flow directions, by rotation of the bioreactor, and/or combinations thereof.
1. A method of growing cells in a bioreactor, the method comprising:
circulating a first fluid at a first flow rate through a bioreactor of a cell expansion system, wherein the first fluid comprises a reagent;
circulating the first fluid for a first period of time to allow at least a first portion of the reagent to coat the bioreactor;
after the first period of time, circulating the first fluid at a second flow rate slower than the first flow rate through the bioreactor of the cell expansion system for a second period of time to allow a second portion of the reagent to coat the bioreactor;
circulating a second fluid through the bioreactor to remove a third portion of the reagent from the bioreactor;
circulating a third fluid at a third flow rate through a bioreactor of a cell expansion system, wherein the third fluid comprises a plurality of cells;
reducing circulation of the third fluid from the third flow rate;
maintaining the bioreactor in a first orientation for a third predetermined period of time to allow at least a portion of the plurality of cells to settle;
after the third predetermined period of time, rotating the bioreactor to a second orientation that is about 180 degrees from the first orientation;
after the rotating, maintaining the bioreactor in the second orientation for a fourth period of time to allow at least a second portion of the plurality of cells to settle; and
expanding at least the first and the second portion of cells in the bioreactor.
2. The method of claim 1 , further comprising:
after the third predetermined period of time and before the maintaining the bioreactor in the second orientation for a fourth period of time:
circulating the third fluid at a fourth flow rate through the bioreactor, wherein the fourth flow rate is slower than the third flow rate; and
reducing the circulation from the fourth flow rate; and
maintaining the bioreactor in the second orientation for the fourth period of time.
3. The method of claim 2 , further comprising:
after the fourth predetermined period of time:
circulating the third fluid at a fifth flow rate through the bioreactor, wherein the fifth flow rate is slower than the fourth flow rate;
reducing a rate of circulation of the third fluid from the fifth flow rate; and
maintaining the bioreactor in the second orientation for a fifth predetermined period of time to allow at least a third portion of the plurality of cells to settle.
4. The method of claim 3 , further comprising:
after the fifth predetermined period of time:
circulating fluid at a sixth flow rate through the bioreactor, wherein the sixth flow rate is slower than the fifth flow rate; and
reducing circulation of fluid from the sixth flow rate; and
maintaining the bioreactor in the second orientation for a sixth predetermined period of time to allow at least a fourth portion of the plurality of cells to settle.
5. The method of claim 4 , wherein the third period of time, the fourth period of time, the fifth period of time, and the sixth period of time are the same.
6. The method of claim 5 , wherein the third period of time and the fourth period of time are equal in duration.
7. The method of claim 6 , wherein the first period of time is less than about 10 minutes.
8. The method of claim 7 , wherein the bioreactor comprises a hollow fiber membrane.
9. The method of claim 1 , further comprising:
after the second predetermined period of time and before expanding, rotating the bioreactor 180 degrees to the first orientation.