[The effect of serum concentration on the growth, proliferation and collagen secretion in mouse L929 fibroblasts]

To observe the effect of serum concentration on the growth, proliferation and secretion of collagen I, collagen III and hydroxyproline in mouse fibroblasts L929, to optimize serum concentration for cell growth, proliferation and collagen secretion.

L929 cells were divided into 6 groups cultured in the present of 0 mL/L, 200 mL/L, 400 mL/L, 600 mL/L, 800 mL/L and 1 000 mL/L serum respectively. Acridine Orange and HE staining were performed on 2 d, 4 d, 6 d and 8d and sulforhodamine B sulfonyl chloride was used to determine cell proliferation at the same time; Meanwhile, the supernatants of each group ware collected and enzyme immunoassay was performed to detect the protein levels of collagen I, III and hydroxyproline.

(1) The cell proliferation was inhibited when serum concentration was very high (100%) or very low (0%). The proliferation rate in the presence of 20% serum was the highest. When serum concentration was higher than 20%( 40%-100%), the cell proliferation decreased. (2) Apoptotic cells were observed in the absence of serum. Vacuolization appeared in the presence of 80% serum, and was enhanced in the case of 100% serum. Cells were morphologically normal when serum concentrations were between 20%-60%. (3)The level of collagen I was low in the case of serum concentrations of 0%, 80% and 100%, with the highest expression in 40% serum. Collagen III in all groups was increased on day 2, followed by a transient decreased and an final increased on day 6-8. The level of hydroxyproline was not changed in all groups.

The serum concentrations between 20%-40% is suitable for L929cells growth, proliferation and secret collagen. The extremes serum concentration of too high or too low leads to inhibition of cell proliferation, apoptosis, vacuolization, and impaired secretion of collagens. This study indicates the requirement of optimum serum concentration for self serum injection therapy.