Large scale fermenter inoculation with frozen cells

An improved method of inoculating large scale fermenters with mammalian cells is provided. Instead of taking one or more ampules of frozen cells through a series of scale up steps in tissue culture flasks and/or roller bottles, the cells are inoculated into a small fermenter in advance of their anticipated usage in fermenter inoculation. The cells are concentrated and dispensed into approximately 500 ml aliquots (or larger) and mixed with a cryopreservative solution. The aliquots are frozen in liquid nitrogen in specially designed freezer bags. The cells can thus be held indefinitely. When a fermenter run is to be initiated, a cell bag can simply be thawed and inoculated into the fermenter. Because the cells have been previously adapted to the fermenter medium, cell growth and production begin almost immediately after inoculation.