抄録
Although many bio-active proteins and vectors for gene therapy are produced by mammalian cell culture, its efficiency should be improved. Culture media are very expensive because serum or its derivatives are essential for them, and so there is concern about the risk such as BSE. Therefore inexpensive, safe and potent mitogenic supplement for mammalian cell culture is eagerly desired. In this study, sericin, a protein derived from silkworm, was considered as such a factor. In the presence of sericin, the proliferation of all mammalian cell lines tested were accelerated. In comparison with bovine serum albumin, a widely used supplement in serum-free medium, sericin had better effect on the proliferation of human hepatoma HepG2. Although most of proteins are easily inactivated by autoclave sterilization, mitogenic activity of sericin was not damaged after autoclave. As well as sericin derived from silkworm, recombinant sericin peptide synthesized by E.coli stimulated the proliferation of mammalian cells. In cell therapy or bio-artificial organs, stable storage and supply of the cells are crucial. Therefore the effect of sericin on cryopreservation was tested. Sericin was added to the freezing medium and HepG2 cells, which several groups have used in bio-artificial liver, were frozen at -80°C for three days. Cells were thawed out, cultured for one day and the viable cell number was determined. Supplementation of sericin improved the viable cell number by 27%. These results indicate that sericin is a novel and suitable mitogenic supplement for mammalian cell culture as well as supplement for cyropreservation.
