Process for culturing adherent cells

1. A process for producing adherent cells comprising:

a) introducing a suspension of adherent cells into a culture vessel containing microcarriers in a culture medium, wherein the culture vessel is in direct physical contact with the culture medium;

b) amplifying the cells by performing a plurality of cell passages in the same culture vessel, wherein each cell passage subsequent to the first cell passage is carried out:

i) by retaining in the culture vessel all or part of the cells produced during the previous cell passage after having subjected the cells to enzyme treatment in the culture vessel to detach the cells from microcarriers without removing the all or part of the cells produced during the previous cell passage from the culture vessel, and

ii) by introducing culture medium and an increasing amount of microcarriers into the culture vessel; and

c) harvesting the cells produced during the last cell passage, optionally after having subjected the cells to enzyme treatment to detach cells from microcarriers.

2. A process for producing a biological agent from adherent cells, comprising:

a) introducing a suspension of adherent cells into a culture vessel containing microcarriers in a culture medium;

b) amplifying the cells by performing a plurality of cell passages in the same culture vessel wherein each cell passage subsequent to the first cell passage is carried out:

i) by using all or part of the cells produced during the previous cell passage after having subjected the cells to enzyme treatment to detach the cells from microcarriers; and

ii) by introducing culture medium and an increasing amount of microcarriers;

c) treating the cells produced during the last cell passage such that it produces the biological agent, wherein said treating is carried out in the same culture vessel as the one used to amplify the cells; and

d) harvesting the biological agent.

3. The process as claimed in claim 2 , wherein the biological agent is an infectious agent and wherein the treatment of the cells in part c) is carried out by infecting the cells with said infectious agent in an infection medium.

4. The process as claimed in claim 3 , wherein the infectious agent is rabies virus and wherein the infection medium is a viral infection medium free of any product of animal origin.

5. The process as claimed in claim 1 , wherein the number of cell passages carried out in the same culture vessel is 2, 3 or 4.

6. The process as claimed in claim 1 , wherein the microcarrier concentration in the culture medium during the first cell passage is <1 g/l.

7. The process as claimed in claim 1 , wherein the enzyme treatment employs a solution containing a proteolytic enzyme.

8. The process as claimed in claim 1 , wherein each cell passage subsequent to the first cell passage is carried out by increasing the volume of the culture medium.

9. The process as claimed in claim 1 , wherein the first cell passage is carried out in a volume of culture medium that is between ⅕ and half the working volume of the culture vessel.

10. The process as claimed in claim 1 , wherein the culture medium is free of serum of animal origin.

11. The process as claimed in claim 1 , wherein the culture medium is free of product of animal origin.

12. The process as claimed in claim 1 , wherein the protein concentration in the culture medium is ≦15 mg/l.

13. The process as claimed in claim 1 , wherein the culture medium contains a cell protection agent.

14. The process as claimed in claim 13 , wherein the cell protection agent is a polyvinylpyrrolidone or a poloxamer.

15. The process as claimed in claim 1 , wherein the culture vessel is a bioreactor that has a working volume of between 3 and 3000 liters.

16. The process as claimed in claim 15 , wherein the culture vessel is a bioreactor that has a working volume of between 20 and 500 liters.

17. The process as claimed in claim 15 , wherein the culture vessel is a disposable bioreactor.

18. The process as claimed in claim 1 , wherein the adherent cells are Vero cells.

19. The process as claimed in claim 1 , wherein the cells harvested in part c) contains at least 60 times more cells than the number of cells that were initially introduced in part a), and wherein the cells are Vero cells.

20. A process for producing adherent cells comprising:

a) thawing a stock of adherent cells, and then

b) subjecting the thawed adherent cells to the process as claimed in claim 1 .

21. The process for producing cells adherent to microcarriers as claimed in claim 1 , further comprising:

a) transferring the harvested cells after having subjected the cells to enzyme treatment to detach cells from microcarriers, into a second culture vessel the working volume of which is larger than the working volume of the first culture vessel and that contains a culture medium containing microcarriers in a larger amount than the amount of microcarriers that was present during the last cell passage carried out in the first culture vessel from which the cells were harvested, and

b) performing parts b) and c) as claimed in claim 1 to the cells transferred into the second culture vessel.

22. The process for producing adherent cells according to claim 1 , wherein the amount of cells produced is increased by a factor ≧60, and wherein the cells are Vero cells.

23. The process as claimed in claim 7 , wherein the proteolytic enzyme is trypsin.