Transportation and cryopreservation may impair haematopoietic stem cell function and engraftment of allogeneic PBSCs, but not BM

Abstract

Recent data suggest that the practice of using frozen allogeneic grafts is becoming increasingly common among transplant centres. Therefore, we retrospectively analysed 31 frozen allogeneic PBSC and 8 BM grafts by flow cytometry with regard to their CD34 þ content, membrane integrity (7-AAD) and stem cell-specific enzyme activity (aldehyde dehydrogenase, ALDH) in relation to individual transplantation results. Membrane integrity of CD34 þ cells was significantly impaired in cryopreserved PBSC but not in BM compared to unfrozen allografts. In 9 out of 31 frozen PBSC (but none of the BM) grafts numbers of SSC lo ALDH br cells per kg body weight (BW) were significantly reduced while in the same grafts the numbers of CD34 þ cells per kg BW were close to normal. Overall, 9 out of 33 patients (27%) who received unrelated PBSC allografts cryopreserved after transportation did not achieve engraftment. For comparison, primary graft failure was observed in our centre in only 7 out of 493 recipients (1.4%) of fresh allogeneic PBSC grafts. Moreover, we did not see any graft failure in patients receiving frozen/thawed BM or autologous PBSC transplants. We, therefore, conclude that PBSC grafts become much more sensitive to cryopreservation after transport and/or storage. Importantly, the engraftment potential of frozen HSC grafts may reliably be predicted by measuring ALDH activity.

Cryopreservation of allogeneic PBSC from related and unrelated donors is associated with delayed platelet engraftment but has no impact on survival

“…5 PBSC may be more sensitive than BM to the effects of cryopreservation. 8 Kim et al 7 noted that megakaryocyte colony-forming units suffered significantly greater loss of viability after cryopreservation of PBSC than those of the granulocytic and erythroid lineages, which may explain our observation. Despite this, in clinical data using those cryopreserved PBSC, Kim et al 7 observed no differences in time to platelet engraftment, although patients receiving cryopreserved PBSC with CFU-Meg in the lowest quartile did demonstrate slower platelet engraftment to 4100 Â 10 9 /L.…”

“…One study of cryopreserved PBSC in MUD allo-SCT reported a strikingly high incidence of primary engraftment failure. 8 Reassuringly in our study the rate of primary engraftment failure did not significantly differ between cryopreserved and fresh PBSC, and of the six patients who received cryopreserved PBSC and subsequently required a stem cell 'top-up' only one was a MUD transplant.…”

“…In particular, allo-SCT carries the risk of immunological rejection of the graft. As cryopreservation might compromise stem cell dose, viability or donor lymphocyte function, 8 the evidence that cryopreservation does not significantly impair engraftment is required before its use can be recommended.…”

“…Univariate analyses were performed using the log-rank test for Multivariate analyses of OS and RFS were performed using Cox proportional hazards models, and multivariate analyses of events with a competing risk were performed according to the method of Fine and Gray. 8 Factors differing in distribution between the outcome groups with a P-value of less than 0.1 by univariate analysis, in addition to fresh vs cryopreserved PBSC, were included in an initial multivariate model. Models were refined using a backward approach until only significant associations remained.…”

“…Lioznov et al 8 in a study of 46 patients, 35 receiving MUD allografts, found that stem cell viability and CD34 þ cell membrane integrity were significantly impaired in PBSC, but not in BM, after cryopreservation. Worryingly, 9 of 33 cryopreserved PBSC grafts, all from MUD, failed to engraft.…”