Cell cryopreservation provides high quality cells for clinical application and scientific studies. Specifically

20% (v/v) FBS supplemented with 10% (v/v) DMSO are widely used in cryoprotectants. However

high concentrations of DMSO are cytotoxic to cells

and FBS exhibits problems related to diseases such as bovine spongiform encephalopathy and viral infections. Silk protein is a type of natural macromolecule fiber protein with good biocompatibility. The aim of the study involved testing the effectiveness of the silk protein as cryoprotectant and developing a novel FBS-free and low concentration DMSO freezing medium. Meishan pig ear fibroblast cells were cryopreserved by using a freezing medium in the presence of various mass concentrations of silk sericin and various volume fractions of silk fibroin. The preservation efficiency was evaluated by trypan blue dye exclusion test

MTT assay

and the 24 h adherent rate after thawing. The results indicate that the survival rate of cryopreserved cells does not significantly differ when the cells are cryopreserved with a freezing medium containing 1% (w/v) sericin and 20% (v/v) FBS

and this indicates that sericin can substitute for FBS in the freezing medium. A significant difference is absent between 10% (v/v) fibroin protein with 5% (v/v) DMSO and 10% (v/v) DMSO

and thus the fibroin decreases the concentration of DMSO. Finally

5% (v/v) DMSO supplemented with 1% (w/v) sericin and 10% (v/v) fibroin exhibit similar results as a control group.