Comparing the ability of freshly generated and cryopreserved dendritic cell vaccines to inhibit growth of breast cancer in a mouse model

Repetitive vaccinations with dendritic cell (DC)-based vaccines over long periods of time can break pre-existing tolerance to tumors and achieve clinically relevant immune response. This requires a large number of DCs to be generated under good manufacturing protocol, which is time- and cost intensive. Thus, producing a large numbers of DCs at one time point and cryopreserving these cells in ready-for-use aliquots for clinical application may overcome this constraint. This could also reduce batch-to-batch variations. In this study, we generated DCs from bone marrow obtained from BALB/c mice. Some of the generated DCs were cryopreserved before conducting various tests. There were no significant differences in the morphology and phenotype between cryopreserved and freshly generated DCs. Both types of DCs pulsed with tumor lysate (TL) from 4T1 murine mammary cancer cells (DC+TL) possessed a similar capacity to stimulate the proliferation of T-cells. In addition, cryopreserved and fresh DC pulsed with TL showed similar tumor growth inhibition patterns. Both DCs induced initial retardation of tumor growth (p<0.05) and prolonged the survival (p<0.05) of tumor-bearing mice treated with DC+TL as compared with nontreated control mice. Cryopreserved DCs shared similar therapeutic efficacy to fresh DCs, and this finding lends supports the routine use of cryopreserved DCs in future clinical trials.