DRAIN DOWN AND RE-FEED OF MICROCARRIER BIOREACTOR

The invention provides a method of increasing product yield per culture in a population of product-secreting cells bound to a scaffold, for example, a microcarrier, at least partially immersed in a culture medium in a bioreactor. The method comprising: semi-harvesting product by removing a volume of the culture medium with a first-secreted product concentration while leaving the scaffold with the bound cells in the bioreactor; re-feeding the cells by adding a fresh culture medium to increase the culture medium in the bioreactor to approximately the original volume; agitating the culture medium to allow the cells to grow and release a second-secreted product concentration; harvesting product by removing the culture medium with the second-secreted product concentration while leaving the scaffold with the bound cells behind. Also disclosed is a method of increasing virus yield per culture in a population of virus-infected cells bound to a microcarrier suspended in a culture medium.