Serum-free culture medium and preparation method and application therefor

1. A serum-free medium for expansion culture of human umbilical cord mesenchymal stem cells (hUC-MSCs) in vitro, wherein the serum-free medium consists of 90-95 parts by volume of a-MEM or DMEM-F12 , 0.05-0.2 parts by volume of β-mercaptoethanol, 0.5-2 parts by volume of aqueous solution of non-essential amino acids, recombinant human basic fibroblast growth factor (b-FGF) at a final concentration of 5-15 ng/ml and 4-6 parts by volume of a concentrate of culture supernatant of human umbilical cord mesenchymal stem cells (hUC-MSCs),

wherein the aqueous solution of non-essential amino acids comprises glycine, alanine, L-asparagine, L-aspartic acid, glutamic acid, proline and serine, each at a concentration of 8-12 mM,

wherein the concentrate of culture supernatant is produced by a method consisting of the following steps:

(1) inoculating human umbilical cord mesenchymal stem cells in a serum-free medium at a density of 0.5-4×10 4 cells/cm 2 and culturing the cells for 48-72 hours to allow the cells to reach 70%-90% confluence, and then collecting fresh culture supernatant of the umbilical cord mesenchymal stem cells;

(2) centrifuging the culture supernatant at 3000-5000 g for 15-40 min at 4° C., to remove cells and cellular debris suspended therein;

(3) centrifuging the supernatant obtained from step (2) at 10000 g for 30-60 min at 4° C., to remove cytoplasm and other impurities therein;

(4) filtering the supernatant obtained from step (3) through a 0.22 μm microfiltration membrane, to sterilize the supernatant;

(5) transferring a filtrate obtained from step (4) to a 3 KD ultrafiltration concentrator tube, and centrifuging at 3000-4500 g for 60-90 min at 4° C., to concentrate the filtrate to 1/20 to 1/50 of its original volume; and

(6) adjusting the concentrate obtained from step (5) with PBS to get a final volume of 1/20 of the volume of the culture supernatant collected in step (1),

wherein the serum-free medium in step (1) consists of 0.05-0.2 parts by volume of β-mercaptoethanol, 0.5-2 parts by volume of aqueous solution of non-essential amino acids, 90-95 parts by volume of a-MEM or DMEM-F12, and recombinant human basic fibroblast growth factor at a final concentration of 5-15 ng/ml, and the aqueous solution of non-essential amino acids comprises glycine, alanine, L-asparagine, L-aspartic acid, glutamic acid, proline and serine each at a concentration of 8-12 mM.

2. The serum-free medium according to claim 1 , wherein the serum-free medium consists of 0.1 part by volume of β-mercaptoethanol, 1 part by volume of aqueous solution of non-essential amino acids, 5 parts by volume of the concentrate of culture supernatant, 94 parts by volume of a-MEM or DMEM-F12 and the recombinant human basic fibroblast growth factor at a final concentration of 10 ng/ml.

3. The serum-free medium according to claim 1 , wherein in step (1), the human umbilical cord mesenchymal stem cells (hUC-MSCs) are human umbilical cord mesenchymal stem cells isolated from a fresh umbilical cord tissue of a healthy newborn by natural or cesarean section delivery.

4. A method for preparing the serum-free medium according to claim 1 , wherein the method includes collecting a culture supernatant of human umbilical cord mesenchymal stem cells by performing the steps (1)-(6) of claim 1 , to obtain a concentrate of the culture supernatant;

preparing a premixture using β-mercaptoethanol, non-essential amino acids and a-MEM or DMEM-F12; and

mixing the concentrate of the culture supernatant, the premixture and recombinant human basic fibroblast growth factor.

5. The serum-free medium according to claim 1 , wherein the serum-free medium in step (1) consists of 0.1 part by volume of β-mercaptoethanol, 1 part by volume of aqueous solution of non-essential amino acids, 94 parts by volume of a-MEM or DMEM-F12 and the recombinant human basic fibroblast growth factor at a final concentration of 10 ng/ml.