Cell culture method using bone marrow-like structure, and porous polyimide film for healing bone injury site

1. A method of inducing differentiation from bone marrow cells derived from a mammal to hematocytes, comprising:

(1) applying a first cell group consisting of the bone marrow cells to a porous polyimide film and culturing it;

(2) applying a second cell group consisting of the bone marrow cells to the porous polyimide film after the culturing in step (1), and culturing it; and

(3) adding a differentiation-inducing accelerating substance to the porous polyimide film after the culturing in step (2), and culturing, to accelerate differentiation from the bone marrow cells to the hematocytes,

wherein the porous polyimide film has a three-layer structure consisting of an A-surface layer having a plurality of pores, a B-surface layer having a plurality of pores, and a macro-void layer sandwiched between the two surface layers,

a mean pore size in the A-surface layer is smaller than a mean pore size in the B-surface layer, and

the macro-void layer has a partition bonded to the A-surface layer and the B-surface layer, and a plurality of macro-voids surrounded by the partition, the A-surface layer, and the B-surface layer.

2. The method according to claim 1 , further including recovering the hematocytes.

3. The method according to claim 1 , wherein the hematocytes are erythroid progenitor cells or erythrocytes.

4. 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.

5. The method according to claim 4 , 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.

6. The method according to claim 1 , using two or more porous polyimide films layered either above and below or left and right in the cell culture medium.

7. The method according to claim 1 , wherein the porous polyimide film is:

i) folded,

ii) wound into a roll,

iii) connected as sheets or fragments by a filamentous structure, or

iv) bound into a rope,

and used by suspension or anchoring in the cell culture medium in the cell culturing vessel.

8. The method according to claim 1 , wherein the differentiation-inducing accelerating substance is selected from the group consisting of colony-stimulating factor, granulocyte colony stimulating factor, stem-cell factor, stem cell growth factor-α, erythropoietin, thrombopoietin and interleukin.

9. The method according to claim 1 , wherein the differentiation-inducing accelerating substance is erythropoietin.