Abstract: A bioreactor system for culturing cells, cellular aggregates, tissues and organoids and methods of using same includes a cylindrical reactor vessel having an unobstructed longitudinal axis that is rotated about that horizontal axis to suspend cells and/or tissue in a culture medium. Filters are used within the vessel to retain the cells and/or tissues within the culture chamber and may be also used to subdivide the culture chamber. A pump maintains a flow of oxygen rich culture medium through the vessel to sustain cell respiration. A gas exchange device maintains desired gas concentrations in the medium and the entire system is operated within an enlarged incubator to maintain appropriate temperatures. Access ports on the vessel are used to introduce various materials into the culture chamber and to remove bubbles that may form in the medium. Sensors and a microprocessor unit monitor operational conditions and direct adjustments to maintain desired conditions.