Long-term cell-cultivation using polyimide porous membrane and cell-cryopreservation method using polyimide porous membrane

1. A cell cryopreservation method, including:

(1) a step of supporting cells on a porous polyimide film,

(2) a step of placing the cell-supporting porous polyimide film under conditions in which the cells freeze, to freeze the cells supported on the porous polyimide film, and

(3) a step of storing the cell-supporting porous polyimide film under conditions in which the frozen state is maintained,

wherein the porous polyimide film with a multilayer structure, having at least two surface layers (an A-surface and a B-surface), and a macro-void layer sandwiched between the two surface layers,

a mean pore size of the holes in the A-surface is smaller than a mean pore size of the holes in the B-surface, and the macro-void layer has a partition bonded to the surface layers (the A-surface and the B-surface), and a plurality of macro-voids surrounded by the partition and the surface layers (the A-surface and the B-surface).

2. The method according to claim 1 , wherein in step (1), the cells are seeded on the porous polyimide film to support the cells on the porous polyimide film.

3. The method according to claim 1 , wherein in step (1), the cells are seeded and cultured on the porous polyimide film to support the cells on the porous polyimide film.

4. The method according to claim 1 , which further includes, following step (3),

(4) a step of placing the cell-supporting porous polyimide film under conditions in which the cells thaw, to thaw the cells supported on the porous polyimide film.

5. The method according to claim 4 , which further includes, following step (4),

(5) a step of applying the cell-thawed porous polyimide film to a cell culture medium and culturing the cells.

6. The method according to claim 5 , wherein in step (5), the cells are cultured until the cultured cells proliferate even outside of the porous polyimide film.

7. The method according to claim 5 , wherein in step (5), the one or more separate non-cell-supporting porous polyimide films are applied onto the cell culture medium together with the cell-thawed porous polyimide film, and culturing is carried out to support the cells on the one or more separate porous polyimide films.

8. The method according to claim 5 , which further includes, following step (5),

(6) a step of placing all or a portion of the cell-supporting porous polyimide film under conditions in which the cells freeze, to freeze the cells supported on the porous polyimide film, and

(7) a step of storing the cell-supporting porous polyimide film under conditions in which the frozen state is maintained.

9. The method according to claim 8 , wherein steps (1) to (7) are repeated several times.

10. The method according to claim 1 , wherein the cells are selected from the group consisting of animal cells, insect cells, plant cells, yeast cells and bacteria.

11. The method according to claim 10 , wherein the animal cells are cells derived from an animal belonging to the subphylum Vertebrata.

12. The method according to claim 10 , wherein the cells are adherent cells.

13. The method according to claim 10 , wherein the cells are suspension cells.

14. The method according to claim 1 , wherein the porous polyimide film is a porous polyimide film including a polyimide obtained from a tetracarboxylic dianhydride and a diamine.

15. The method according to claim 14 , wherein the porous polyimide film is a colored porous polyimide film obtained by forming a polyamic acid solution composition including a polyamic acid solution obtained from a tetracarboxylic dianhydride and a diamine, and a coloring precursor, and then heat treating it at 250° C. or higher.

16. A kit for use in the method according to claim 1 , including a porous polyimide film and a cell cryopreservation liquid,

wherein the porous polyimide film with a multilayer structure, having at least two surface layers (an A-surface and a B-surface), and a macro-void layer sandwiched between the two surface layers,

a mean pore size of the holes in the A-surface is smaller than a mean pore size of the holes in the B-surface, and the macro-void layer has a partition bonded to the surface layers (the A-surface and the B-surface), and a plurality of macro-voids surrounded by the partition and the surface layers (the A-surface and the B-surface).