Satisfactory recovery and viability of stem cells cryopreserved at high cell concentration

Peripheral Blood Stem Cells (PBSC) are being extensively used in both oncology-haematology and in solid tumor therapy schedules. The latest generation of cell separators allow the collection of greater numbers of nucleated cells (NC) than is usually obtained in bone marrow transplantation (BMT) settings. Thus, larger volumes of components would be stored if the same NC concentration employed in BMT is to be used. In order to reduce large volume DMSO-infusion related side effects and to avoid storage problems, we froze components from 23 PBSC collections at higher NC concentrations, from 40-200 x 10(6)/mL. After 2-12 months of storage, we thawed the samples and determined if the high NC concentration had a detrimental effect on NC viability and on stem cell clonogenicity. No statistically significant differences emerged in regard to CFU-GM, CFU-GEMM and BFU-E percent recovery even at 200 x 10(6)/mL NC concentration.