An effective method for recovering CD34 positive progenitor cells from peripheral blood stem cell apheresis products...

The use of small volume collection chamber (SVCC) during peripheral blood stem cell (PBSC) apheresis, combined with simplified cryopreservation without rate-controlled freezing, have successfully been applied to clinical PBSC transplantation following myeloablative chemotherapies. However, the method to effectively select CD34+ progenitor cells from frozen apheresis products obtained with these simplified methods has not been reported. For this goal, after washing the thawed apheresis products with medium containing Dnase I, two different approaches to purify CD34+ progenitor cells from washed WBCs were compared. In method I, CD34+ cells were purified on the same day using immunomagnetic method. In method II, the cells after wash were cultured for overnight in RPMI-1640/10% FCS containing SCF and IL-3, followed by enrichment of CD34+ cells as in method I on the next day. In both methods, CD34+ cells were recovered with high viability. However, subsequent liquid culture revealed that the cells obtained from method II have clearly higher growth potential compared with the cells from method I. In addition, these CD34+ cells from method II well-tolerated to further refreeze and thaw. Thus, allowing to "rest" overnight after thaw may be critical for processing of the simply cryopreserved apheresis products as in method II.