Fig. 3.

Fixed-bed reactor system for the differentiation of encapsulated stem cells. The bio-reactor consists of a sterile plastic syringe filled with cell capsules as bed. The cell capsules are transferred into the reactor from an inoculum vessel. The following cultivation runs automatically with a perfusion of the reactor with preconditioned medium. Oxygen measurements are performed on-line with optical sensors (IPO2) at the in- and the outlet of the reactor. Medium exchange is done if necessary whereby the exchanged medium is collected in the waste vessel. After completion of the differentiation, the cell capsules are cryopreserved. Therefore, they are automatically washed with PBS, followed by addition of a cryoprotective medium.