The effect of age of refrigerated conditioned medium on cell survivability in vitro

Samples of a conditioned medium (CM), obtained from human ginvigal fibroblasts culture, were kept at 4 degrees C each for 2 weeks, 1, 2, 3 and 6 months. Their effectiveness in maintaining cell survival for their contact with L929 cells in 96 well tissue culture plates for 6 and 10 h at 4 degrees C was compared with Hank's Balanced Salt Solution (HBSS). Surviving cells were stained with neutral red dye and the dye intensity was measured spectrophotometrically at 540 nm. The target cells responded to all the above mentioned CM and the HBSS in the same manner at 6-h contact time. However, by 10-h contact time, the percentage of the target cells' survival was higher in the 2-week, 1- and 2-month CM than in HBSS, 3- and 6-month CM.