Variable resistance to freezing and thawing of CD34-positive stem cells and lymphocyte subpopulations in leukapheresis products

Abstract

Background aimsLeukapheresis products for hematopoietic stem cell transplantation can be cryopreserved for various indications. Although it is known that CD34+ cells tolerate cryopreservation well, a significant loss of CD3+ cells has been observed, which has been ascribed to several factors, including transport, storage conditions and granulocyte-colony stimulating factor (G-CSF) administration. MethodsTo assess the tolerance of CD34+ cells and lymphocyte subpopulations for cryopreservation and thawing, the post-thaw recoveries of CD34+ cells, CD3+CD4+ cells, CD3+CD8+ cells, CD19+ cells and CD16+CD56+ cells were determined in 90 cryopreserved apheresis products, among which 65 were from G-CSF–mobilized donors, and 34 from unrelated donors that underwent transport before cryopreservation at our center. A controlled rate freezer and 5% dimethyl sulfoxide were used for cryopreservation. ResultsWe could detect statistically significant differences for CD34+ cell recovery (93.0 ± 20.7%) when compared to CD3+CD4+ cell (83.1 ± 15.4%, P = 0.014), and CD3+CD8+ cell recovery (83.3 ± 13.9%, P = 0.001). Similarly, CD19+ cell recovery (98.6 ± 15.1%) was higher than CD3+CD4+ cell (P = 2.5 × 10−7) and CD3+CD8+ cell recovery (P = 1.2 × 10−8). Post-thaw recovery rates of all cell populations were not impaired in G-CSF–mobilized products compared with non-mobilized products nor in unrelated compared with related donor products. DiscussionOur data suggest a lower tolerance of CD3+ cells for cryopreservation and demonstrate that freezing–thawing resistance thawing is cell-specific and independent from other factors that affect post-thaw recovery of cryopreserved cells. Thus, a clinical consequence may be the monitoring of post-thaw CD3+ cell doses of cryopreserved products, such as donor lymphocyte infusions.