Background aims: Infusion of stem cell autografts can be associated with adverse effects. Necrotic normal leukocytes, cytokines or intracellular mediators released from leukocytes and platelets or the cryo-protectant dimethyl sulfoxide (DMSO) may contribute to this. Cryopreservation using 5% instead of 10% DMSO improves CD34(+) cell viability and therefore we investigated whether using less DMSO had favorable outcomes on leukocyte viability and levels of various soluble mediators in the graft supernatant.
Methods: Peripheral blood autografts were harvested by 20 apheresis procedures in 16 cancer patients, and autograft samples were cryopreserved with 2%, 4%, 5% and 10% DMSO and stored for 5-6 years. After thawing, the viability of neutrophils and lymphocytes was analyzed by flow cytometry and supernatant levels of soluble mediators were determined by enzyme-linked immunosorbent assay (ELISA) analyzes.
Results: The highest viability of both neutrophils and lymphocytes was detected with 4% and 5% DMSO, whereas decreased viability was observed with 2% and 10% DMSO. Low or undetectable levels of leukocyte-derived interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha and CXCL8, high levels of platelet-derived CCL5 and CXCL4, and high levels of monocyte-derived soluble CD14 were measured independent of the DMSO concentration, except for slightly increased CXCL8 and decreased CXCL4 levels with 2% DMSO. Perforin levels showed a significant inverse correlation with the DMSO concentration.
Conclusions: The use of different DMSO concentrations affects the viability of normal leukocytes in autologous peripheral blood stem cell grafts, but has only minor effects on supernatant levels of leukocyte- and platelet-derived soluble mediators.