Cell culture system

A bag comprising:

• one or more polymer films, having edges bonded together to form edges around an undivided interior compartment of the bag;
• a first port formed in an exterior surface of the bag;
• a first liquid-permeable tube extending into and in fluid communication with the interior compartment of the bag, the first liquid-permeable tube being operatively coupled to the first port;
• a second port formed in an exterior surface of the bag;
• a second liquid-permeable tube extending into and in fluid communication with the interior compartment of the bag, the second liquid-permeable tube being operatively coupled to the second port;
• and
• optionally, a third port formed in an exterior surface of the bag, the third port being in fluid communication with the interior compartment of the bag;
• wherein the first liquid-permeable tube comprises
• a first inner support structure defining a central lumen of the first liquid-permeable tube, wherein the first inner support structure comprises a spiral-wound filament, wherein a spacing of the spiral-wound filament is at least 100 μm;
• and
• a first outer filter layer surrounding the first inner support structure, wherein the first outer filter layer has an average pore size of less than 50 μm.