Cell Expansion Vessel Systems and Methods

A method includes introducing a suspension including cells suspended in a cell culture medium through a feed port or a drain port into a cavity of a cell culture vessel, the suspension being in an amount sufficient to cover a gas permeable, liquid impermeable membrane positioned at a bottom of the cell culture vessel, the feed port being disposed through a surface of the cell culture vessel and configured to permit additional cell culture medium into the cavity, and the drain port being disposed through the surface of the cell culture vessel and configured to permit removal of the cells, cell culture medium, and used cell culture medium from the cavity, allowing the cells to settle on the gas permeable, liquid impermeable membrane by gravity, removing the used cell culture medium through the drain port and introducing the additional cell culture medium through the feed port such that a constant volume is maintained in the cell culture vessel until the cells expand to a desired cell density, wherein the removing and introducing are performed subsequent to allowing the cells to settle on the gas permeable, liquid impermeable membrane, resuspending the cells in the cell culture medium in the cell culture vessel, wherein the resuspending is performed after the desired cell density is attained, and removing the resuspended cells and the cell culture medium through the drain port.