After the MCB was safety tested and characterized, a portion of the batch was thawed and used to seed the bioreactor for the Working Cell Bank (WCB) production. Cells were cultured in the bioreactor until they reached D13. They were harvested (Centritech LAB-III, Carr Centritech Separation System, Rancho Cucamonga, CA, USA), aliquoted (Fill-It; TAP Biosystems, Wilmington, DE, USA), and cryopreserved to create a WCB. The WCB was subjected to release testing for safety and characterization assays. Safety testing included sterility (USP <71>), mycoplasma (USP <63), endotoxin (USP <85>), and karyotyping (Cell Line Genetics, Madison WI, USA). Characterization included flow cytometry testing for: Oct-4 >90% (10H11.2, EMD Millipore, Billerica, MA, USA; AF488 conjugated), Sox-2 >90% (Btjce, eBioscience, San Diego CA, USA; AF488 conjugated), MHC-I <10% (A4, eBioscience; APC conjugated), MHC-II <10% (CVS20, Novus Biologicals, Littleton CO, USA; AF488 conjugated), CD105 <10% (SN6, eBioscience; PE-Cy7 conjugated), and tyrosine hydroxylase <10% (EP1532Y, Abcam, Cambridge, UK; FITC conjugated goat anti-rabbit IgG; Abcam; polyclonal). Both MCB and WCB were stored in gas phase LN2 at -196°C.