Fixed bed cell culture reactor vessel for substrate alignment and sampling

A fixed bed bioreactor for culturing cells on a cell culture substrate, the fixed bed bioreactor comprising:

• a cell culture vessel comprising a vessel body defining at least one interior reservoir configured to hold a multi-layered cell culture substrate, an inlet fluidly connected to the reservoir, and an outlet fluidly connected to the reservoir, the vessel body comprising a first end, a second end, and a longitudinal axis extending in a direction from the first end to the second;
• a cell culture substrate disposed in the interior reservoir in a stacked arrangement;
• and
• a guide rod disposed in the interior reservoir and extending parallel to the longitudinal axis of the vessel body,
• wherein the guide rod is configured to hold in place the cell culture substrate in the interior reservoir.
• wherein the cell culture substrate is a multi-layer cell culture substrate, and
• wherein the guide rod is configured to maintain a rotational alignment of individual layers of the multi-layered cell culture substrate with respect to other individual layers of the multi-layered cell culture substrate.