Avoiding room temperature storage and delayed cryopreservation provide better postthaw potency in hematopoietic progenitor cell grafts.

BACKGROUND: Conditions for maintaining hematopoietic progenitor cells (HPCs) before cryopreservation remain controversial. An understanding of the impact of time and temperature during nonfrozen storage can contribute to the maintenance of the quality of products, improving transplantation outcomes. The objective of this study was to determine the influence on cell potency of thawed products from three sources of HPCs after prolonged storage at different temperatures before cryopreservation. STUDY DESIGN AND METHODS: Viable cell counts by flow cytometry and colony-forming unit (CFU) recoveries were assessed on cord blood (CB), mobilized peripheral blood stem cell (PBSC), and bone marrow (BM) samples over 72 hours using two different storage conditions, refrigerated (4-8°C) or room temperature (19-22°C). To determine the effects of delayed freezing on progenitor recoveries, paired samples were evaluated before and after cryopreservation. RESULTS: All samples maintained at refrigerated temperatures resulted in higher recoveries than those at room temperature in all variables assessed. Specifically, when assessing for CFU yields after thawing, the impact of time on BM resulted in a significant loss as soon as 24 hours (n = 10, 36.4 ± 28.0%, p = 0.003). This decrease was also observed for PBSCs and CB but at 48 hours of fresh storage (PBSCs n = 11, 32.7 ± 26.2%, p = 0.006; CB n = 10, 39.6 ± 26.4%, p = 0.001). CONCLUSION: Our data suggest that HPC products are better maintained at refrigerated temperatures before cryopreservation. Delaying cryopreservation should be minimized to avoid significant losses in cell potency.

Cord blood banking: 'providing cord blood banking for a nation'.

Transplantation of cord blood (CB) is increasingly used as therapy for patients whose own marrow is affected by genetic mutations that prevent the development of normal cells of the blood or immune tissues, or for patients whose marrow has been destroyed in the course of treatment for leukaemia and other malignancies. CB is a rich source of haematopoietic stem cells, can be easily harvested and stored in frozen aliquots in a CB bank. The first public CB bank was established in 1993 allowing unrelated CB transplantation to become an option for patients lacking a suitable adult donor. Today, the results of CB transplantation are comparable to those of bone marrow transplants with several important advantages: the graft is available 'off the shelf', thereby reducing the waiting time, and the requirements of human lecucoyte antigen (HLA) matching are less restrictive than those of adult sources. The reduced requirement for HLA matching allows transplants between incompletely matched donors and recipients, thus reducing the size of the inventory required at the national level. This also mitigates the disadvantage encountered by persons of rare HLA genotypes or those who do not belong to populations of North Western European descent. Finally, national CB programmes can easily make available for research individual surplus units not meeting minimal criteria for clinical use.

The impact of donor factors on primary non-engraftment in recipients of reduced intensity conditioned transplants from unrelated donors.

BACKGROUND AND OBJECTIVES: Primary graft failure is a serious complication following hematopoietic cell transplants, particularly when using unrelated donors. We analyzed factors affecting primary graft failure in recipients of hematopoietic cell transplants from unrelated donors, which were performed using reduced intensity conditioning. DESIGN AND METHODS: This was a retrospective analysis of 144 patients whose transplants took place between March 1998 and October 2004. The data were analyzed in January 2005. RESULTS: The median age of the patients was 51 years. The diagnoses were varied. Conditioning regimens were fludarabine, melphalan, campath (n=80), fludarabine, busulphan, campath (n=38), fludarabine, BEAM, campath (n=9) and other (n=17). The donor was 10/10 allele matched in 95/144 (66%) cases; 94 donated bone marrow and 50 peripheral blood stem cells. The 3-year probability of overall survival was 43%. The median follow-up was 724 days (range: 91-1651 days). Of evaluable patients, 7/140 (5%) failed to achieve myeloid engraftment. Primary graft failure was significantly associated with the use of a mismatched donor (6/47,13% versus 1/93, 1%, p=0.006), as well as: bone marrow as the source of stem cells (p=0.046), chronic myeloid leukemia compared to other diagnoses (p=0.022), and a female rather than a male donor (p=0.019). In multivariate analysis chronic myeloid leukemia, HLA mismatched and/or female donors remained significantly associated with primary graft failure. Single HLA mismatches were tolerated, however in multiply mismatched grafts, overall survival was worse (p=0.005); transplanted-related mortality (p=0.005) and chronic graft-versus-host disease (p=0.025) were increased. INTERPRETATION AND CONCLUSIONS: These data have implications for the choice of donor and stem cell source in transplants performed using reduced intensity conditioning regimens, suggesting that the use of bone marrow, female donors and HLA-mismatched grafts increase the risk of primary graft failure, and should be avoided in certain situations.