Rapid transport and infusion of hematopoietic cells is associated with improved outcome after myeloablative therapy and unrelated donor transplant

Assessing deviations for HPCs obtained during COVID-19 (ADHOC): Evaluating impact of the COVID-19 pandemic on cellular therapy products and processes, the BEST collaborative study

BACKGROUND

The success of allogeneic hematopoietic stem cell transplantation is dependent on a world-wide network of collection centers providing donations that predominantly have been infused as fresh cells. The logistics chain that supports the just-in-time delivery model for stem cell and immunotherapy products was severely stressed by the COVID pandemic, and in early 2020 a number of national and international bodies recommended that cells should be cryopreserved at the collection or transplant center to avoid interruptions in their acquisition or delivery to patients who had started conditioning.

STUDY DESIGN

To assess the potential consequences of such pandemic-related deviations to normal practice, we surveyed nine international laboratories to determine if the characteristics or transplant outcomes of allogeneic stem cell donations differed in the immediate periods before and after the switch to routine cryopreservation.

RESULTS

Nine centers on two continents provided data for 72 HSC donations just before, and 71 just after, switching to cryopreservation for allogeneic HSC products. No statistically significant differences between the period before and after cryopreservation were noted for time from product collection to receipt, product temperature at receipt, or CD34⁺ cell viability at receipt. There was an indication of slower absolute neutrophil count recovery after cryopreservation was required (mean time of 15 vs. 17.6 days).

DISCUSSION

While there were no apparent changes to most parameters studied, there was an indication of slower neutrophil engraftment that will need to be examined in larger, longer term studies.

The impact of transportation time on apoptosis in allogeneic stem cell grafts and the clinical outcome in malignant patients with unrelated donors

BACKGROUND

The quality of cells in peripheral blood stem cell (PBSC) grafts is important for allogeneic stem cell transplantation outcome. The viability of PBSC grafts may decrease during transportation time between donor and transplant center. We hypothesize that the graft viability based on apoptosis and necrosis in the graft may better reflect graft quality and clinical outcome.

METHODS

PBSC graft viability from unrelated donors was analyzed in 91 patients. Viable cells were defined as 7-aminoactinomycin D- and Annexin V-negative. The clinical outcome, including survival, transplant-related mortality and graft-versus-host disease (GvHD), was correlated to graft viability.

RESULTS

Grafts transported for 1 day had a median viability of 86.4% (range 63.8 to 98.9%), and grafts transported for 2 days had median viability of 83.2% (range 52.8% to 96.2%) (P = .003). Grafts were divided into two groups based on the median graft viability of 85.1%. Patients who received low viability grafts had lower 1-year survival of 63.7% compared with 88.9% for those who received high viability grafts (P = .007). In the multivariate analysis, transplant-related mortality (TRM) was higher in the low viability group (P = .03), whereas overall survival was not significantly associated with graft viability. The incidence of acute GvHD grade II to IV, chronic GvHD and relapse risk remained comparable between the groups.

CONCLUSION

Low graft viability was an independent predictor of 1-year survival and TRM after adjusting for multiple confounders. Better graft quality markers are important for the detection of clinically important variations in the stem cell graft.

The Effect of Donor Graft Cryopreservation on Allogeneic Hematopoietic Cell Transplantation Outcomes: A Center for International Blood and Marrow Transplant Research Analysis. Implications during the COVID-19 Pandemic

The COVID-19 pandemic has resulted in the increased use of cryopreserved grafts for allogeneic hematopoietic cell transplantation (HCT). However, information about the effect of cryopreservation on outcomes for patients receiving allogeneic donor grafts is limited. We evaluated outcomes of HCT recipients who received either fresh or cryopreserved allogeneic bone marrow (BM) or peripheral blood stem cell (PBSC) grafts reported to the Center for International Blood and Marrow Transplant Research. A total of 7397 patients were included in the analysis. Recipients of cryopreserved graft were divided into 3 cohorts based on graft source: HLA-matched related PBSC donors (n = 1051), matched unrelated PBSC donors (n = 678), and matched related or unrelated BM donors (n = 154). These patients were propensity score matched with 5514 patients who received fresh allografts. The primary endpoint was engraftment. Multivariate analyses showed no significant increased risk of delayed engraftment, relapse, nonrelapse mortality (NRM), or survival with cryopreservation of BM grafts. In contrast, cryopreservation of related donor PBSC grafts was associated with decreased platelet recovery (hazard ratio [HR], 0.73; 95% confidence interval [CI], 0.68 to 0.78; P < .001) and an increased risk of grade II-IV (HR, 1.27; 95% CI, 1.09 to 1.48; P = .002) and grade III-IV (HR, 1.48; 95% CI, 1.19 to 1.84; P < .001) acute graft-versus-host disease. Cryopreservation of unrelated PBSC grafts was associated with delayed engraftment of neutrophils (HR, 0.77; 95% CI, 0.71 to 0.84; P < .001) and platelets (HR, 0.61; 95% CI, 0.56 to 0.66; P < .001) as well as an increased risk of NRM (HR, 1.4; 95% CI, 1.18 to 1.66; P < .001) and relapse (HR, 1.32; 95% CI, 1.11 to 1.58; P = .002) and decreased progression-free survival (HR, 1.36; 95% CI, 1.20 to 1.55; P < .001) and overall survival (OS) (HR, 1.38; 95% CI, 1.22 to 1.58; P < .001). Reasons for cryopreservation were not routinely collected; however, in a subset of unrelated donor HCT recipients, the reason was typically a change in patient condition. Products cryopreserved for patient reasons were significantly associated with inferior OS in multivariate analysis (HR, 0.65; 95% CI, 0.44 to 0.96; P = .029). We conclude that cryopreservation is associated with slower engraftment of PBSC grafts, which may be associated with inferior transplantation outcomes in some patient populations. However, the small numbers in the cryopreserved BM cohort and the lack of information on the reason for cryopreservation in all patients suggests that these data should be interpreted with caution, particularly in the context of the risks associated with unexpected loss of a graft during the pandemic. Future analyses addressing outcomes when cryopreservation is universally applied are urgently required.

Meeting the Demand for Unrelated Donors in the Midst of the COVID-19 Pandemic: Rapid Adaptations by the National Marrow Donor Program and Its Network Partners Ensured a Safe Supply of Donor Products

The impact of the coronavirus disease 2019 (COVID-19) pandemic on hematopoietic cell transplant (HCT) donor registries and transplant center (TC) practices is underreported. This article reports on the National Marrow Donor Program (NMDP) Be The Match Registry and its coordinating the provision of unrelated donor (URD) products to domestic and international TCs during the initial 3 months of the COVID-19 pandemic (March through May 2020). Specifically, NMDP data are presented for disease indications for transplant, URD search volumes and availability, graft requests and processing, courier utilization and performance, and conversion rates from formal donor search and workup to graft collection and shipment. Data following the onset of COVID-19 are compared to the immediate 3 months prior to the COVID-19 pandemic (December 2019 through February 2020) and the same quarter 1 year prior to COVID-19 (March through May 2019). During the initial onset of COVID-19 and compared to 1 year prior, TCs requested and the NMDP performed less donor searches. More multiple URD and direct to workup requests were processed by the NMDP, which likely reflected reductions in donor availability. Yet TCs continued to perform allogeneic transplants for acute disease indications like acute leukemia and myelodysplasia, using more cryopreserved grafts than before COVID-19. In comparison to prepandemic patient cycle conversion rates and durations, the NMDP was able to convert patient cycles at nearly the same or higher rates and in similar or shorter periods of time. Last, despite significant challenges caused by the pandemic, including interruptions in domestic courier services and travel restrictions, graft products were delivered to and received by TCs in similar periods of time than before COVID-19. Taken together, these data show that NMDP service line operations continued to function effectively during the early phases of the COVID-19 pandemic, ensuring requests for and delivery of URD products to domestic and international allogeneic HCT recipients.

Development of an Unrelated Donor Selection Score Predictive of Survival after HCT: Donor Age Matters Most

Donor factors, in addition to HLA matching status, have been associated with recipient survival in unrelated donor (URD) hematopoietic cell transplantation (HCT); however, there is no hierarchical algorithm that weights the characteristics of individual donors against each other in a quantitative manner to facilitate donor selection. The goal of this study was to develop and validate a donor selection score that prioritizes donor characteristics associated with better survival in 8/8 HLA-matched URDs. Two separate patient/donor cohorts, the first receiving HCT between 1999 and 2011 (n = 5952, c1), and the second between 2012 and 2014 (n = 4510, c2) were included in the analysis. Both cohorts were randomly spilt, 2:1, into training and testing sets. Despite studying over 10,000 URD transplants, we were unable to validate a donor selection score. The only donor characteristic associated with better survival was younger age, with 2-year survival being 3% better when a donor 10 years younger is selected. These results support previous studies suggesting prioritization of a younger 8/8 HLA-matched donor. This large dataset also shows that none of the other donor clinical factors tested were reproducibly associated with survival, and hence flexibility in selecting URDs based on other characteristics is justified. These data support a simplified URD selection process and have significant implications for URD registries.

Cryopreservation of adult unrelated donor products in hematopoietic cell transplantation: the OneMatch experience and systematic review of the literature

BACKGROUND

The frequency of cryopreserving blood stem or progenitor products from unrelated donors is not known and the underlying reasons are poorly documented. Greater insight is needed to develop policies on cryopreservation that balance donor safety with patient needs.

STUDY DESIGN AND METHODS

Cryopreservation requests between January 1, 2014, and May 31, 2016, at the OneMatch Stem Cell and Marrow Network at Canadian Blood Services were reviewed and a systematic review of the literature was performed.

RESULTS

Thirty products of 719 (4.2%) unrelated donor collections facilitated by OneMatch were cryopreserved. Patient-related reasons were most common and included the need to delay transplant for continued antimicrobial treatment (six patients), patient too deconditioned to proceed with scheduled transplant (five patients), and/or need for more treatment for relapsed disease (three patients). Donor-related issues leading to cryopreservation requests were less common (five cases), mainly due to lack of donor availability after attempting to reschedule. Cryopreservation of a product that was never infused occurred infrequently (two cases, 7%). In our systematic review of the literature, 993 cases were identified in 32 published reports. Both patient-related and donor-related reasons were cited but not specifically reported, precluding quantitative insight regarding the relative frequency of causes. The impact of cryopreservation on hematopoietic engraftment appears negligible when compared to controls in a subset of studies; however, reporting of outcomes was inconsistent.

CONCLUSION

Future studies with standard outcome measures are needed to clarify the impact of cryopreservation on engraftment and other transplant outcomes. International guidelines that consider the ethical framework surrounding requests for donor product cryopreservation are needed.

Alternative Donor Transplantation with High-Dose Post-Transplantation Cyclophosphamide for Refractory Severe Aplastic Anemia

Severe aplastic anemia (SAA) is a life-threatening hematopoietic stem cell disorder that is treated with bone marrow transplantation (BMT) or immunosuppressive therapy (IST). The management of patients with refractory SAA after IST is a major challenge. Alternative donor BMT is the best chance for cure in refractory SAA, but morbidity and mortality from graft failure and complications of graft-versus-host disease (GVHD) have limited enthusiasm for this approach. Here, we employed post-transplantation high-dose cyclophosphamide in an effort to safely expand the donor pool in 16 consecutive patients with refractory SAA who did not have a matched sibling donor. Between July 2011 and August 2016, 16 patients underwent allogeneic (allo) BMT for refractory SAA from 13 haploidentical donors and 3 unrelated donors. The nonmyeloablative conditioning regimen consisted of antithymocyte globulin, fludarabine, low-dose cyclophosphamide, and total body irradiation. Post-transplantation cyclophosphamide 50 mg/kg/day i.v. on days +3 and +4 was administered for GVHD prophylaxis. Additionally, patients received mycophenolate mofetil on days +5 through 35 and tacrolimus from day +5 through 1 year. The median age of the patients at the time of transplantation was 30 (range, 11 to 69) years. The median time to neutrophil recovery over 1000 × 103/mm3 for 3 consecutive days was 19 (range, 16 to 27) days, to red cell engraftment was 25 (range, 2 to 58) days, and to last platelet transfusion to keep platelets counts over 50 × 103/mm3 was 27.5 (range, 22 to 108) days. Graft failure, primary or secondary, was not seen in any of the patients. All 16 patients are alive, transfusion independent, and without evidence of clonality. The median follow-up is 21 (range, 3 to 64) months. Two patients had grade 1 or 2 skin-only acute GVHD. These same 2 also had mild chronic GVHD of the skin/mouth requiring systemic steroids. One of these GVHD patients was able to come off all IST by 15 months and the other by 17 months. All other patients stopped IST at 1 year. Nonmyeloablative alloBMT using post-transplantation cyclophosphamide allowed for safe expansion of the donor pool to include HLA-haploidentical donors. This approach appears promising in refractory SAA patients. Importantly, engraftment was 100%, pre-existing clonal disease was eradicated, and the risk of GVHD was low.

Graft Transit Time Has No Effect on Outcome of Unrelated Donor Hematopoietic Cell Transplants Performed in Australia and New Zealand: A Study from the Australasian Bone Marrow Transplant Recipient Registry

A previous study found that platelet recovery and mortality were worse in recipients of myeloablative bone marrow transplants where graft transit times were longer than 20 hours. This retrospective study of unrelated myeloablative allogeneic transplantation performed within Australia and New Zealand analyzed transplant outcomes according to graft transit times. Of 233 assessable cases, 76 grafts (33%) were sourced from bone marrow (BM) and 157 (67%) from peripheral blood. Grafts sourced from Australia and New Zealand (47% of total) were associated with a median transit time of 6 hours versus 32 hours for overseas sourced grafts (53% of total). Graft transit temperature was refrigerated in 85%, ambient in 6%, and unknown in 9% of cases, respectively. Graft transit times had no significant effect on neutrophil or platelet engraftment, treatment-related mortality, overall survival, and incidence of acute or chronic graft-versus-host disease. Separate analysis of BM grafts, although of reduced power, also showed no significant difference in either neutrophil or platelet engraftment or survival between short and longer transport times. This study gives reassurance that both peripheral blood stem cell and especially BM grafts subjected to long transit times and transported at refrigerated temperatures may not be associated with adverse recipient outcomes.

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

BACKGROUND AIMS

Leukapheresis 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.

METHODS

To 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.

RESULTS

We 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.

DISCUSSION

Our 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.

The effect of donor characteristics on survival after unrelated donor transplantation for hematologic malignancy

There are >24 million registered adult donors, and the numbers of unrelated donor transplantations are increasing. The optimal strategy for prioritizing among comparably HLA-matched potential donors has not been established. Therefore, the objective of the current analyses was to study the association between donor characteristics (age, sex, parity, cytomegalovirus serostatus, HLA match, and blood group ABO match) and survival after transplantation for hematologic malignancy. The association of donor characteristics with transplantation outcomes was examined using either logistic or Cox regression models, adjusting for patient disease and transplantation characteristics associated with outcomes in 2 independent datasets: 1988 to 2006 (N = 6349; training cohort) and 2007 to 2011 (N = 4690; validation cohort). All donor-recipient pairs had allele-level HLA typing at HLA-A, -B, -C, and -DRB1, which is the current standard for selecting donors. Adjusting for patient disease and transplantation characteristics, survival was better after transplantation of grafts from young donors (aged 18-32 years) who were HLA matched to recipients (P < .001). These findings were validated for transplantations that occurred between 2007 and 2011. For every 10-year increment in donor age, there is a 5.5% increase in the hazard ratio for overall mortality. Increasing HLA disparity was also associated with worsening survival. Donor age and donor-recipient HLA match are important when selecting adult unrelated donors. Other donor characteristics such as sex, parity, and cytomegalovirus serostatus were not associated with survival. The effect of ABO matching on survival is modest and must be studied further before definitive recommendations can be offered.

Human bone marrow processing using a new continuous-flow cell separation device

BACKGROUND

Processing of bone marrow (BM) is often required to remove incompatible red blood cells (RBCs) or to reduce the volume before transplantation or cryopreservation. We have evaluated the Spectra Optia apheresis system to determine its effectiveness in volume reduction and RBC depletion of human BM before transplantation.

STUDY DESIGN AND METHODS

BM from 30 donations (28 allogeneic and two autologous) were processed using the Spectra Optia over a 12-month period. The mean BM collection volume was 1094 ± 337 mL and RBC volume was 374 ± 148 mL. Processing using the Spectra Optia was as described by the manufacturer.

RESULTS

Volume reduction achieved was 93.0 ± 1.2%; RBC depletion was 98.8 ± 0.4%; and mononuclear, CD34+, and CD3+ cell recoveries were 79.12 ± 14.03, 88.36 ± 13.76, and 79.84 ± 16.27%, respectively. In total 26 of 28 processed allografts were transplanted; 24 achieved neutrophil engraftment in 20.7 ± 5.9 days and 18 achieved platelet engraftment in 19.6 ± 8.9 days. Time in transit significantly affected the Spectra Optia's ability to recover mononuclear, CD34+, and CD3+ cells, and the overall age of the BM at the time of processing significantly affected the recovery of mononuclear and CD3+ cells, but not CD34+ cells. Time in storage at 2 to 6°C had no adverse effect on processing.

CONCLUSION

This study demonstrates that the Spectra Optia can effectively volume reduce and RBC deplete human BM before transplantation. Time in transit should be as short as possible but may be extended up to 24 hours if the donation is refrigerated during transit.

Quality of the hematopoietic stem cell graft affects the clinical outcome of allogeneic stem cell transplantation

BACKGROUND

In approximately two-thirds of patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT) no suitable related donor can be identified but an unrelated HLA-matched donor can be found through international donor registries. HSCT grafts from unrelated donors are commonly collected at distant sites. Therefore, graft storage and transportation becomes crucial in the HSCT process. We aimed to study the impact of graft quality on clinical outcome and identify factors affecting graft quality.

STUDY DESIGN AND METHODS

We investigated the influence of graft quality on the clinical outcome in 144 HSCT patients. Graft quality was assessed by determining the viability (7-aminoactinomycin D [7AAD]) on a frozen-thawed sample from the peripheral blood stem cell (PBSC) graft.

RESULTS

Patients receiving PBSCs with inferior quality (i.e., viability < 64% in the frozen-thawed sample) more frequently developed acute graft-versus-host disease (aGVHD) Grades I to IV than patients receiving grafts with better quality (p = 0.025). The transplant-related mortality (TRM) was higher in the group receiving grafts with lower viability (p = 0.03). The viability of the frozen-thawed samples was highly variable (median, 64%; range, 24%-96%). No correlation could be observed when comparing the viability in newly arrived PBSC grafts to frozen-thawed vials. Grafts with white blood cell (WBC) count of more than 300 × 10(9) /L had lower viability than those with lower WBC counts (p < 0.001).

CONCLUSION

Graft quality affects clinical outcome. Patients receiving grafts with inferior quality had more aGVHD and higher TRM. There is a need for better analyses for assessing graft quality in routine HSCT care; analysis using 7AAD on fresh PBSC grafts is not sufficient.

Multi-institutional study of post-transplantation cyclophosphamide as single-agent graft-versus-host disease prophylaxis after allogeneic bone marrow transplantation using myeloablative busulfan and fludarabine conditioning

PURPOSE

The clinical safety and efficacy of intravenous busulfan and fludarabine (IV Bu/Flu) myeloablative conditioning as well as graft-versus-host disease (GVHD) prophylaxis with high-dose, post-transplantation cyclophosphamide (PTCy) have been demonstrated independently in several single-institutional studies. We hypothesized that combining these two promising approaches in a multi-institutional study of human leukocyte antigen (HLA) -matched bone marrow transplantation would provide low rates of severe acute and chronic GVHD, low toxicity, and effective disease control.

PATIENTS AND METHODS

Ninety-two adult patients (median age, 49 years; range, 21 to 65 years) with high-risk hematologic malignancies were enrolled at three centers (clinical trial No. NCT00809276). Forty-five patients received related allografts, and 47 received unrelated allografts. GVHD prophylaxis was solely with PTCy at 50 mg/kg/day on post-transplantation days +3 and +4.

RESULTS

The cumulative incidences of grades 2 to 4 acute, grades 3 to 4 acute, and chronic GVHD were 51%, 15%, and 14%, respectively. Nonrelapse mortality (NRM) at 100 days and 1 year were 9% and 16%, respectively. With a median follow-up period of 2.2 years, the 2-year disease-free survival (DFS) and overall survival (OS) rates were 62% and 67%, respectively. Donor relatedness did not affect NRM, DFS, or OS. Patients in complete remission (CR) without evidence of minimal residual disease (MRD) had markedly better DFS (80%) and OS (80%) than patients in CR with MRD or with active disease at the time of transplantation (DFS, P = .0005; OS, P = .019).

CONCLUSION

This multi-institutional study demonstrates that PTCy can be safely and effectively combined with IV Bu/Flu myeloablative conditioning and confirms PTCy's efficacy as single-agent, short-course GVHD prophylaxis for both acute and chronic GVHD after bone marrow transplantation from HLA-matched donors.

Effects of storage temperature on hematopoietic stability and microbial safety of BM aspirates

Bone marrow (BM) remains a common source for hematopoietic SCT. Due to the transcutaneous approach, contamination with skin bacteria is common. The delay between harvest and transfusion can be considerable, potentially allowing for bacterial proliferation. The optimal transportation temperature, specifically with respect to bacterial growth and consequences thereof for hematopoietic quality, remain undefined. For 72 h, 66 individual BM samples, non-spiked/spiked with different bacteria, stored at 20-24 °C room temperature (RT) or 3-5 °C (cold), were serially analyzed for hematopoietic quality and microbial burden. Under most conditions, hematopoietic quality of BM was equal or better at RT: Typical BM contaminants (P. acnes and S. epidermidis) and E. coli were killed or bacterial proliferation was arrested at RT; hematopoietic quality was not impacted by the contamination. However, several pathogenic bacteria not typically found in BM (S. aureus and K. pneumoniae) proliferated dramatically at RT and impaired hematopoietic quality. Bacterial proliferation was arrested in the cold. The overwhelming majority of BM samples, that is, those that are sterile or contaminated only with skin commensals, will benefit from transportation at RT. Those bacteria that proliferate and perturb hematopoietic quality are not typically found in BM. Our data support recommendations for RT transportation and storage of BM.

Analysis of the recovery of cryopreserved and thawed CD34+ and CD3+ cells collected for hematopoietic transplantation

BACKGROUND

Cryopreservation is often used to store cellular therapies, but little is known about how well CD3+ or CD34+ cells tolerate this process.

STUDY DESIGN AND METHODS

Viable CD34+ cell recoveries were analyzed from related and unrelated donor granulocyte-colony-stimulating factor (G-CSF)-mobilized peripheral blood stem cell (PBSC) products and viable CD3+ cell recoveries from G-CSF-mobilized and nonmobilized apheresis products from related and unrelated donors. All products were cryopreserved with 5% dimethyl sulfoxide and 6% pentastarch using a controlled-rate freezer and were stored in liquid nitrogen. Related donor products were cryopreserved immediately after collection and unrelated donor products greater than 12 hours postcollection.

RESULTS

The postthaw recovery of CD34+ cells from related donor PBSCs was high (n = 86; 97.5 ± 23.1%) and there was no difference in postthaw CD34+ cell recovery from unrelated donor PBSCs (n = 14; 98.8 ± 37.2%; p = 0.863). In related donor lymphocyte products the postthaw CD3+ cell recovery (n = 48; 90.7 ± 21.4%) was greater than that of unrelated donor products (n = 14; 66.6 ± 35.8%; p = 0.00251). All unrelated donor lymphocyte products were from G-CSF-mobilized products, while most related donor lymphocyte products were from nonmobilized products. A comparison of the CD3+ cell recovery from related donor G-CSF-mobilized products (n = 19; 85.0 ± 29.2%) with that of unrelated donor products found no significant difference (p = 0.137).

CONCLUSIONS

The postthaw recovery of CD34+ cells was high in both related and unrelated donor products, but the recovery of CD3+ cells in unrelated donor G-CSF-mobilized products was lower. G-CSF-mobilized unrelated donor products may contain fewer CD3+ cells than non-G-CSF-exposed products upon thaw and, when indicated, cell doses should be monitored.