Characterization of mouse 3T3-swiss albino cells available in Japan: necessity of quality control when used as feeders.

Mouse 3T3-Swiss albino cells are widely used as feeder cells to culture the human epidermis for the treatment of burns. To minimize the risk of xenoinfection, quality control of the feeder cells is required in the Japanese guidelines on regenerative medicine using feeder cells. We characterized three lots of 3T3-Swiss albino cells that are publicly or commercially available in Japan. One lot, which propagated more rapidly than the other two without showing typical contact inhibition, was found to release endogenous murine leukemia virus upon iododeoxyuridine-treatment. Southern blotting of restriction fragments showed that the rapidly growing lot consisted of genetically altered cells that had probably emerged during the passages. The data support the guidelines that recommend the quality control of each lot of 3T3-Swiss albino cells if they are to be used clinically.