Leukopaks from mobilized peripheral blood are collected from healthy human donors under IRB approved informed consent by leukapheresis using the Spectra Optia® Apheresis System CMNC collection protocol. Donors are injected with G-CSF, which stimulates the bone marrow to produce a large number of hematopoietic and progenitor stem cells and mobilizes them into the peripheral blood stream. This mononuclear cell-rich leukapheresis product is extracted using continuous flow centrifugal technology directly into the collection bag.