No difference in graft-versus-host disease, relapse, and survival comparing peripheral stem cells to bone marrow using unrelated donors

Unravelling human hematopoietic progenitor cell diversity through association with intrinsic regulatory factors

Hematopoietic stem and progenitor cell (HSPC) transplantation is an essential therapy for hematological conditions, but finer definitions of human HSPC subsets with associated function could enable better tuning of grafts and more routine, lower-risk application. To deeply phenotype HSPCs, following a screen of 328 antigens, we quantified 41 surface proteins and functional regulators on millions of CD34+ and CD34- cells, spanning four primary human hematopoietic tissues: bone marrow, mobilized peripheral blood, cord blood, and fetal liver. We propose more granular definitions of HSPC subsets and provide new, detailed differentiation trajectories of erythroid and myeloid lineages. These aspects of our revised human hematopoietic model were validated with corresponding epigenetic analysis and in vitro clonal differentiation assays. Overall, we demonstrate the utility of using molecular regulators as surrogates for cellular identity and functional potential, providing a framework for description, prospective isolation, and cross-tissue comparison of HSPCs in humans.

Kinetics of immune cell reconstitution predict survival in allogeneic bone marrow and G-CSF-mobilized stem cell transplantation

The clinical utility of monitoring immune reconstitution after allotransplant was evaluated using data from Blood and Marrow Transplant Clinical Trials Network BMT CTN 0201 (NCT00075816), a multicenter randomized study of unrelated donor bone marrow (BM) vs granulocyte colony-stimulating factor (G-CSF)-mobilized blood stem cell (G-PB) grafts. Among 410 patients with posttransplant flow cytometry measurements of immune cell subsets, recipients of G-PB grafts had faster T-cell reconstitution than BM recipients, including more naive CD4⁺ T cells and T-cell receptor excision circle-positive CD4⁺ and CD8⁺ T cells at 3 months, consistent with better thymic function. Faster reconstitution of CD4⁺ T cells and naive CD4⁺ T cells at 1 month and CD8⁺ T cells at 3 months predicted more chronic graft-versus-host disease (GVHD) but better survival in G-PB recipients, but consistent associations of T-cell amounts with GVHD or survival were not seen in BM recipients. In contrast, a higher number of classical dendritic cells (cDCs) in blood samples at 3 months predicted better survival in BM recipients. Functional T-cell immunity measured in vitro by cytokine secretion in response to stimulation with cytomegalovirus peptides was similar when comparing blood samples from BM and G-PB recipients, but the degree to which acute GVHD suppressed immune reconstitution varied according to graft source. BM, but not G-PB, recipients with a history of grades 2-4 acute GVHD had lower numbers of B cells, plasmacytoid dendritic cells, and cDCs at 3 months. Thus, early measurements of T-cell reconstitution are predictive cellular biomarkers for long-term survival and response to GVHD therapy in G-PB recipients, whereas more robust DC reconstitution predicted better survival in BM recipients.

Impact of conditioning regimen on peripheral blood hematopoietic cell transplant

AIM

To investigate infused hematopoietic cell doses and their interaction with conditioning regimen intensity +/- total body irradiation (TBI) on outcomes after peripheral blood hematopoietic cell transplant (PBHCT).

METHODS

Our retrospective cohort included 247 patients receiving a first, T-replete, human leukocyte antigen-matched allogeneic PBHCT and treated between 2001 and 2012. Correlations were calculated using the Pearson product-moment correlation coefficient. Overall survival and progression free survival curves were generated using the Kaplan-Meier method and compared using the log-rank test.

RESULTS

Neutrophil engraftment was significantly faster after reduced intensity TBI based conditioning [reduced intensity conditioning (RIC) + TBI] and > 4 × 10⁶ CD34+ cells/kg infused. A higher total nucleated cell dose led to a higher incidence of grade II-IV acute graft-versus-host disease in the myeloablative + TBI regimen group (P = 0.03), but no significant difference in grade III-IV graft-versus-host disease. A higher total nucleated cell dose was also associated with increased incidence of moderate/severe chronic graft-versus-host disease, regardless of conditioning regimen. Overall and progression-free survival were significantly better in patients with a RIC + TBI regimen and total nucleated cell dose > 8 × 10⁸/kg (3 years, overall survival: 70% vs 38%, P = 0.02, 3 years, progression free survival: 64% vs 38%, P = 0.02).

CONCLUSION

TBI and conditioning intensity may alter the relationship between infused cell doses and outcomes after PBHCT. Immune cell subsets may predict improved survival after unmanipulated PBHCT.

Allogeneic Hematopoietic Cell Transplantation for Adult Chronic Myelomonocytic Leukemia

Allogeneic hematopoietic cell transplantation (HCT) is potentially curative for patients with chronic myelomonocytic leukemia (CMML); however, few data exist regarding prognostic factors and transplantation outcomes. We performed this retrospective study to identify prognostic factors for post-transplantation outcomes. The CMML-specific prognostic scoring system (CPSS) has been validated in subjects receiving nontransplantation therapy and was included in our study. From 2001 to 2012, 209 adult subjects who received HCT for CMML were reported to the Center for International Blood and Marrow Transplant Research. The median age at transplantation was 57 years (range, 23 to 74). Median follow-up was 51 months (range, 3 to 122). On multivariate analyses, CPSS scores, Karnofsky performance status (KPS), and graft source were significant predictors of survival (P = .004, P = .01, P = .01, respectively). Higher CPSS scores were not associated with disease-free survival, relapse, or transplantation-related mortality. In a restricted analysis of subjects with relapse after HCT, those with intermediate-2/high risk had a nearly 2-fold increased risk of death after relapse compared to those with low/intermediate-1 CPSS scores. Respective 1-year, 3-year, and 5-year survival rates for low/intermediate-1 risk subjects were 61% (95% confidence interval [CI], 52% to 72%), 48% (95% CI, 37% to 59%), and 44% (95% CI, 33% to 55%), and for intermediate-2/high risk subjects were 38% (95% CI, 28% to 49%), 32% (95% CI, 21% to 42%), and 19% (95% CI, 8% to 29%). We conclude that higher CPSS score at time of transplantation, lower KPS, and a bone marrow graft are associated with inferior survival after HCT. Further investigation of CMML disease-related biology may provide insights into other risk factors predictive of post-transplantation outcomes.

Optimal graft source for allogeneic hematopoietic stem cell transplant: bone marrow or peripheral blood?

Peripheral blood (PB), compared with bone marrow graft, has higher stem cell content, leads to faster engraftment and is more convenient for collection. Consequently, the use of PB graft has significantly increased in recent years. Although the use of PB graft is acceptable or even preferred to bone marrow graft in matched related donor allogeneic transplant due to a possibility of improved survival, PB graft increases the risk of chronic graft-versus-host disease and associated long-term toxicities in the setting of matched unrelated donor allogeneic transplant. In haploidentical transplant, mitigation of graft-versus-host disease with the use of post-transplant cyclophosphamide is a hypothesis-generating possibility; however, available studies have significant limitations to draw any definite conclusion.

Effect of Total Nucleated and CD34(+) Cell Dose on Outcome after Allogeneic Hematopoietic Stem Cell Transplantation

During more recent years only few studies have analyzed the effect of total nucleated cell (TNC) and CD34(+) cell dose in allogeneic hematopoietic stem cell transplantation (HSCT). A single-center analysis included 544 patients, 227 with a sibling donor and 317 with an unrelated donor. Most patients (n = 292) were treated with myeloablative conditioning, whereas the remaining patients (n = 252) received reduced-intensity conditioning. Bone marrow (BM) (n = 121) and peripheral blood stem cell (PBSC) grafts (n = 423) were analyzed separately. Median TNC and CD34(+) cell dose was 3.2 × 10(8)/kg versus 11.6 × 10(8)/kg in BM and 3.9 × 10(6)/kg versus 8.1 × 10(6)/kg in PBSC. In the BM group we found a higher TNC and CD34(+) cell dose was associated with a faster neutrophil engraftment (P < .001 and P = .02). In the PBSC group we found patients given a very high (≥11 × 10(6)/kg) CD34(+) cell dose had decreased rates of survival (P = .001) and increased relapse (P = .02). A high CD34(+) cell dose correlated with faster platelet engraftment (P < .01). In HSCT using PBSCs, the CD34(+) cell doses should be kept below 11 × 10(6)/kg but over 2.5 × 10(6)/kg.

Risk Factors, Pattern and Clinical Outcome of Acute Graft Versus Host Disease in Acute Leukemia Patients Undergoing Allogeneic Stem Cell Transplant

We sought to determine risk factors, pattern and outcome of acute graft versus host disease (aGVHD) in seventy-seven acute leukemia patients who underwent allogeneic stem cell transplant at our centre from January 2008 to March 2013. GVHD prophylaxis with cyclosporine-methotrexate or cyclosporine-mycophenolate mofetil was used. Patients were divided in 2 groups, grade II-IV aGVHD (group A) and grade 0-I aGVHD (group B). Incidence of any grade and grade II-IV aGVHD was 44 and 18 %, respectively. The most common site of aGVHD was gastro-intestinal tract (65 %) followed by skin (35 %). Higher total nucleated cell (TNC) dose infused was associated with increased incidence of grade II-IV aGVHD. Incidence of relapse and incidence of slippage of chimerism was 21 and 36 % in group A while 37 and 27 % in group B respectively. Transplant related mortality (TRM) was 21 % in group A and 13 % in group B. Probability of OS and RFS at 4 years was 63 and 34 % in group A compared with 40 and 38 % in group B, respectively. We conclude that higher TNC dose infused is a risk factor for grade II-IV aGVHD with gut being the commonest site. Grade II-IV aGVHD did not have a significant impact on incidence of relapse, TRM and OS.

PBSC vs BM grafts with myeloablative conditioning for unrelated donor transplantation in adults with high-risk ALL

Few studies are available that compare PBSC and BM from unrelated donors, especially in adult high-risk ALL. To determine which graft source is superior in adult high-risk ALL, we analyzed the long-term outcomes of 106 consecutive transplants from 8/8-matched or 7/8-matched unrelated donors (38 PBSC vs 68 BM). All patients received a uniform strategy of pre-transplant therapy, myeloablative conditioning and GVHD prophylaxis. At 5 years, PBSC transplants showed higher incidence of chronic GVHD than did BM transplants (74.3% vs 46.7%, P=0.001). PBSC transplants showed outcomes comparable to those of BM transplants for relapse (23.7% vs 28.1%), non-relapse mortality (18.4% vs 25.0%), disease-free survival (57.9% vs 46.9%) and OS (57.9% vs 50.0%). In a separate comparison of outcomes between the two graft sources according to the presence of a Ph chromosome, no significant advantage of PBSC over BM was found in both subgroups of patients. Our data suggest that the outcomes of unrelated donor transplantation are similar between PBSC and BM in adult high-risk ALL. Whether PBSC should be the preferred graft source for a specific subgroup of adult ALL needs to be further investigated.

Similar outcomes of peripheral blood stem cells vs. bone marrow for human leukocyte antigen-matched unrelated donor transplantation in adult patients with acute myeloid leukemia using risk-adapted graft-versus-host disease prophylaxis

BACKGROUND

In unrelated donor allogeneic stem cell transplantation (URD-SCT), most studies reported that peripheral blood stem cells (PBSC) resulted in higher incidence of acute and/or chronic graft-versus-host disease (GVHD) without survival benefits compared with bone marrow (BM). To overcome these shortcomings of PBSC, we have used a risk-adapted GVHD prophylaxis for patients that received HLA-matched URD-SCT, which was adding low-dose rabbit antithymocyte globulin (Thymoglobulin(®) , 1.25 mg/kg for 2 d) to conditioning in the transplants with PBSC and not BM.

METHODS

To determine whether this strategy is effective, we analyzed 115 adult patients with acute myeloid leukemia who received HLA-matched URD-SCT with PBSC (n = 70) or BM (n = 45) using our risk-adapted GVHD prophylaxis strategy.

RESULTS

The PBSC group showed faster neutrophil (11 d vs. 13 d; P < 0.01) and platelet (12 d vs. 18 d; P < 0.01) engraftment compared with the BM group. No difference was observed in the incidence of acute GVHD grade II-IV at 100 d (54.3% vs. 64.4%; P = 0.38) and chronic GVHD at 4 yr (65.1% vs. 60.0%; P = 0.83). Other outcomes including the incidence of relapse (30.8% vs. 31.2%; P = 0.53), non-relapse mortality (13.5% vs. 6.9%; P = 0.24), disease-free survival (55.7% vs. 61.9%; P = 0.68), and overall survival (62.2% vs. 63.2%; P = 0.96) at 4 yr were not significantly different.

CONCLUSION

Our risk-adapted GVHD prophylaxis strategy resulted in similar transplant outcomes including comparable incidence of GVHD between the PBSC and BM groups in HLA-matched URD-SCT.

Bone marrow or peripheral blood stem cell transplantation from unrelated donors in adult patients with acute myeloid leukaemia, an Acute Leukaemia Working Party analysis in 2262 patients

BACKGROUND

No survival benefit of using blood stem cells instead of bone marrow (BM) has been shown in matched unrelated donor (MUD) transplantation.

DESIGN AND METHODS

In a retrospective registry analysis, we compared the use of blood stem cells (n = 1502) and BM (n = 760) from unrelated donors in patients aged 18-60 years with acute myeloid leukaemia (AML) undergoing myeloablative conditioning between 1997 and 2008. The blood stem cell recipients were older (P < 0.01), had more advanced disease (P < 0.0001) and received less total body irradiation (P < 0.0001) and more antithymocyte globulin (P = 0.01).

RESULTS

Recovery of neutrophils and platelets was faster with blood stem cells (P < 0.0001). The incidence of acute graft-versus-host disease (GVHD) was similar, but there was more chronic GVHD in the blood stem cell group [hazard ratio (HR) = 1.29, P = 0.02]. There were no significant differences in nonrelapse mortality (NRM), relapse incidence and leukaemia-free survival (LFS) between the two groups amongst patients with AML in remission. In patients with advanced leukaemia, NRM was lower (HR = 0.61, P = 0.02) and LFS was prolonged (HR = 0.67, P = 0.002) when blood stem cells were used. At 3 years, LFS for all patients, regardless of remission status, was 41% for both treatment groups. The outcome was not affected after multivariable analysis adjusted for confounders.

CONCLUSION

Blood stem cells compared with BM in MUD transplantation for patients with AML in remission resulted in the same rates of LFS. In patients with advanced leukaemia, the blood stem cell group had reduced NRM and improved LFS.

A characterization of the oral microbiome in allogeneic stem cell transplant patients

BACKGROUND

The mouth is a complex biological structure inhabited by diverse bacterial communities. The purpose of this study is to describe the effects of allogeneic stem cell transplantation on the oral microbiota and to examine differences among those patients who acquired respiratory complications after transplantation.

METHODOLOGY/PRINCIPAL FINDINGS

All patients were consented at the National Institutes of Health, Clinical Center. Bacterial DNA was analyzed from patients' oral specimens using the Human Oral Microbe Identification Microarray. The specimens were collected from four oral sites in 45 allogeneic transplantation patients. Specimens were collected at baseline prior to transplantation, after transplantation at the nadir of the neutrophil count and after myeloid engraftment. If respiratory signs and symptoms developed, additional specimens were obtained. Patients were followed for 100 days post transplantation. Eleven patients' specimens were subjected to further statistical analysis. Many common bacterial genera, such as Streptococcus, Veillonella, Gemella, Granulicatella and Camplyobacter were identified as being present before and after transplantation. Five of 11 patients developed respiratory complications following transplantation and there was preliminary evidence that the oral microbiome changed in their oral specimens. Cluster analysis and principal component analysis revealed this change in the oral microbiota.

CONCLUSIONS/SIGNIFICANCE

After allogeneic transplantation, the oral bacterial community's response to a new immune system was not apparent and many of the most common core oral taxa remained unaffected. However, the oral microbiome was affected in patients who developed respiratory signs and symptoms after transplantation. The association related to the change in the oral microbiota and respiratory complications after transplantation will be validated by future studies using high throughput molecular methods.

A phase II study of sirolimus, tacrolimus and rabbit anti-thymocyte globulin as GVHD prophylaxis after unrelated-donor PBSC transplant

We report on a prospective phase II trial of 32 patients who underwent unrelated donor hematopoietic cell transplantation, with a tacrolimus, sirolimus and rabbit anti-thymoctye globulin GVHD prophylactic regimen. The primary study endpoint was incidence of grades II-IV acute GVHD, with 80% power to detect a 30% decrease compared to institutional historical controls. Median age at transplant was 60 (19-71). Twenty-three patients (72%) received reduced-intensity conditioning, while the remainder received full-intensity regimens. Median follow up for surviving patients was 35 months (range: 21 - 49). The cumulative incidence of acute GVHD was 37.3% and the 2-year cumulative incidence of cGVHD was 63%. We observed TMA in seven patients (21.8%), one of whom also developed sinusoidal obstructive syndrome (SOS). Four patients of 32 (12.5%) failed to engraft, and three of these four died. As a result, enrollment to this trial was closed before the targeted accrual of 60 patients. Two-year overall survival was 65.5% and event-free survival was 61.3%. Two-year cumulative incidence of relapse was 12.5% and non-relapse mortality (NRM) was 15.6%. NRM and aGVHD rates were lower than historical rates; however, the unexpectedly high incidence of graft failure requires caution in the design of future studies with this regimen.

Risk factors for acute GVHD and survival after hematopoietic cell transplantation

Risk factors for acute GVHD (AGVHD), overall survival, and transplant-related mortality were evaluated in adults receiving allogeneic hematopoietic cell transplants (1999-2005) from HLA-identical sibling donors (SDs; n = 3191) or unrelated donors (URDs; n = 2370) and reported to the Center for International Blood and Marrow Transplant Research, Minneapolis, MN. To understand the impact of transplant regimen on AGVHD risk, 6 treatment categories were evaluated: (1) myeloablative conditioning (MA) with total body irradiation (TBI) + PBSCs, (2) MA + TBI + BM, (3) MA + nonTBI + PBSCs, (4) MA + nonTBI + BM, (5) reduced intensity conditioning (RIC) + PBSCs, and (6) RIC + BM. The cumulative incidences of grades B-D AGVHD were 39% (95% confidence interval [CI], 37%-41%) in the SD cohort and 59% (95% CI, 57%-61%) in the URD cohort. Patients receiving SD transplants with MA + nonTBI + BM and RIC + PBSCs had significantly lower risks of grades B-D AGVHD than patients in other treatment categories. Those receiving URD transplants with MA + TBI + BM, MA + nonTBI + BM, RIC + BM, or RIC + PBSCs had lower risks of grades B-D AGVHD than those in other treatment categories. The 5-year probabilities of survival were 46% (95% CI, 44%-49%) with SD transplants and 33% (95% CI, 31%-35%) with URD transplants. Conditioning intensity, TBI and graft source have a combined effect on risk of AGVHD that must be considered in deciding on a treatment strategy for individual patients.

Unrelated donor peripheral blood stem cell transplants incorporating pre-transplant in-vivo alemtuzumab are not associated with any increased risk of significant acute or chronic graft-versus-host disease

There is little information published comparing peripheral blood stem cells (PBSC) with bone marrow (BM) as the stem cell source in the long-term outcome in recipients of T-cell depleted (TCD) unrelated donor (UD) transplants. We present retrospective outcome data on 306 recipients of myeloablative, human leucocyte antigen-matched UD allografts using pre-transplant in-vivo Alemtuzumab. Transplants were performed between 2000 and 2007 for chronic myeloid leukaemia in first chronic phase and acute leukaemia in first or second complete remission; 184 patients received BM and 122 PBSC. The median age was 28·9 years (<1-58) and the median follow-up was 48 months. Overall survival at 8 years was 53%. The incidence of acute graft-versus-host disease (GvHD) was significantly higher in PBSC (65%) than BM recipients (49%; P=0·012). This represented only grade 1 GvHD with no difference in grade II-IV aGvHD (BM 23% PBSC 24%). The incidence of chronic GvHD, either overall (BM 47%, PBSC 49%) or extensive (BM 15%, PBSC 13%) was not increased with PBSC. The incidence of relapse, non-relapse mortality and survival were not significantly different. Whilst accepting the limitations of retrospective analyses, we suggest the increased risk of GvHD in recipients of PBSC in T-replete transplants is offset by in-vivo Alemtuzumab, and that either stem cell source can be used with good outcomes in this setting.

Children with acute leukemia: a comparison of outcomes from allogeneic blood stem cell and bone marrow transplantation

BACKGROUND

The relative merits of peripheral blood stem-cell transplantation (PBSCT) versus bone marrow transplantation (BMT) for children with standard and high-risk hematologic malignancies remain unclear. In a retrospective study, we compared allogeneic PBSCT (n = 30) with BMT (n = 110) in children with acute leukemia between January 2001 and September 2006.

PROCEDURE

Median age for PBSCT was 9 years versus 8 years for BMT. Descriptive statistics were used to summarize the demographic and medical variables. The unadjusted probabilities of disease-free survival were estimated using the Kaplan-Meier method. The association of graft-source and time to each of the study endpoints was estimated by Cox's regression model and the occurrence of graft-versus-host disease (GvHD) was included as a time-dependent covariate.

RESULTS

Time to neutrophil engraftment and platelet independence was faster after PBSCT than BMT (neutrophils 15.0 days vs. 17.0 days, P < 0.001; platelets, 21.0 days vs. 27.0 days, P = 0.034). The cumulative incidence of grades II-IV acute GvHD at 100 days was 10.4% (SE 5.6%) after PBSCT and 15.1% (SE 3.5%) after BMT (P = NS). The cumulative incidence of chronic GvHD was 13.8% (SE 6.3%) after PBSCT and 11.3% (SE 3.1%) after BMT (P = NS). One-year disease-free survival was 37.9% (SE 9.0%) for PBSCT recipients versus 65.1% (SE 4.6%) after BMT (P = 0.005) but this difference was not sustained in multivariate analysis. Thus, only disease risk and pre-transplant CMV seropositivity were significant predictors of disease-free survival.

CONCLUSIONS

We conclude that PBSCT for children produces faster engraftment without increased risk of acute or chronic GvHD.

Higher CD34(+) and CD3(+) cell doses in the graft promote long-term survival, and have no impact on the incidence of severe acute or chronic graft-versus-host disease after in vivo T cell-depleted unrelated donor hematopoietic stem cell transplantation in children

The aim of our study was to compare the results of unrelated donor (UD) peripheral blood stem cell transplantation versus UD bone marrow transplantation and to analyze the impact of infused CD34(+) and CD3(+) cell doses on survival and incidence of severe graft-versus-host disease (GVHD) in 187 children who underwent UD hematopoietic cell transplantation with the use of in vivo T cell depletion (antithymocyte globulin or CAMPATH-1H). HLA typing was performed at the "high-resolution" level. Patients receiving > or =10 x 10(6) CD34(+) cells/kg and > or =4 x 10(8) CD3(+) cells/kg had better overall and disease-free survival. Multivariate analysis has shown that both infused CD34(+) cell dose <10 x 10(6)/kg and CD3(+) cell dose <4 x 10(8)/kg were independent risk factors for mortality (relative risk [RR] 1.8 and 1.71, P = .009 and .016, respectively). Regarding disease-free survival, multivariate analysis has revealed another independent risk factor for poor outcome apart from the 2 earlier-mentioned cell doses, which was the use of donors mismatched at 2 HLA antigens or 3 HLA allele/antigens (RR 2.5, P = .004). In age groups 0-10 years and 10-20 years, CD34(+) cell doses higher than the age-adjusted median dose clearly favored survival. Higher infused doses of CD34(+) and CD3(+) cells did not result in an increased rate of severe GVHD. The use of mismatched donors was the only independent risk factor for the incidence of severe acute GVHD (RR 2.2, P = .046). The report demonstrates for the first time in a pediatric cohort, that higher doses of transplanted CD34(+) and CD3(+) cells lead to an improved survival without an increased risk of severe GVHD. The study findings may be limited to the population of patients receiving in vivo T cell depletion, which is now broadly used in unrelated donor setting in Europe.

Lymphocyte recovery is a major determinant of outcome after matched unrelated myeloablative transplantation for myelogenous malignancies

A higher absolute lymphocyte count 1 month (LC30) after allogeneic hematopoietic stem cell transplantation (HSCT) is associated with better outcome in patients transplanted from a matched sibling. We studied 102 SCT patients with unrelated donor and matched unrelated donors and the relationship between LC30 and outcome in patients with myelogenous leukemia. Conditioning was myeloablative using cyclophosphamide (Cy) with busulfan (Bu; n=61) or total body irradiation (TBI; n=41). LC30 was low (<0.2x10(9)/L) in 18 patients, intermediate (0.2-1.0x10(9)L) in 67, and high (>1.0x10(9)/L) in 17 patients. In multivariate analysis, independent factors associated with high relapse-free survival (RFS) were high LC30, high CD34 cell-dose, and absence of acute graft-versus-host disease (aGVHD) grades II-IV. When analyzed as a continuous variable in multivariate analysis, a higher LC30 was associated with a lower transplant-related mortality (TRM; relative hazard [RH]=0.87, P < .05), higher relapse-free survival (RH=3.42, P=.036), and improved survival (RH=4.53, P=.016, excluding GVHD). In patients with high, intermediate, and low LC30, overall survival (OS) was 91% versus 60%, versus 36% (P=.02 and .001, respectively). This significant relationship was maintained in patients who did not develop GVHD by day 30. Significant risk factors to develop low LC30 was chronic myelogenous leukemia (CML; hazard ratio [HR] 0.73, P=.001), prophylaxis with granulocyte colony-stimulating factor (G-CSF; HR 0.81, P=.02) and aGVHD (HR 0.84, P=.05). These results indicate that LC30 is an independent prognostic factor for transplant outcome in matched unrelated SCT for myelogenous malignancies.

Donor, recipient, and transplant characteristics as risk factors after unrelated donor PBSC transplantation: beneficial effects of higher CD34+ cell dose

We report outcomes of 932 recipients of unrelated donor peripheral blood stem cell hematopoietic cell transplantation (URD-PBSC HCT) for acute myeloid leukemia, acute lymphoblastic leukemia, chronic myelogenous leukemia, and myelodysplastic syndrome enrolled on a prospective National Marrow Donor Program trial from 1999 through 2003. Preparative regimens included myeloablative (MA; N = 611), reduced-intensity (RI; N = 160), and nonmyeloablative (NMA; N = 161). For MA recipients, CD34(+) counts greater than 3.8 x 10(6)/kg improved neutrophil and platelet engraftment, whereas improved overall survival (OS) and reduced transplant-related mortality (TRM) were seen for all preparative regimens when CD34(+) cell doses exceeded 4.5 x 10(6)/kg. Higher infused doses of CD34(+) cell dose did not result in increased rates of either acute or chronic graft-versus-host disease (GVHD). Three-year OS and disease-free survival (DFS) of recipients of MA, RI, and NMA approaches were similar (33%, 35%, and 32% OS; 33%, 30%, and 29% DFS, respectively). In summary, recipients of URD-PBSC HCT receiving preparative regimens differing in intensity experienced similar survival. Higher CD34(+) cell doses resulted in more rapid engraftment, less TRM, and better 3-year OS (39% versus 25%, MA, P = .004; 38% versus 21% RI/NMA, P = .004) but did not increase the risk of GVHD. This trial was registered at www.clinicaltrials.gov as #NCT00785525.

The changing scene of allogeneic stem cell transplantation for chronic myeloid leukemia--a report from the German Registry covering the period from 1998 to 2004

Due to the recent changes in the indication to allogeneic stem cell transplantation (SCT) in chronic myeloid leukemia (CML), we retrospectively analyzed 1,716 patients with different CML stages who received an allograft from related (n = 767) or unrelated donors (n = 938) within the German Registry of Stem Cell Transplantation (DRST) from 1998 to 2004. Myeloablative conditioning was performed in 724/871 cases (83%), dose-reduced conditioning in 147/871 (17%). Annual transplantations were decreasing from 357 to 98 (28%) in the period of study, but the proportion of advanced cases was increasing from 32% (112/346) to 53% (50/94) of all SCTs. Stage of disease, intervals from diagnosis, and patients' age were independent prognostic parameters, while peripheral stem cells and unrelated transplantation seemed equal to bone marrow/related transplantation. This study demonstrates that allo-SCT still has an important role in advanced CML, which emphasizes the need for optimized transplantation strategies for these high-risk patients.

Impact of graft cell dose on transplant outcomes following unrelated donor allogeneic peripheral blood stem cell transplantation: higher CD34+ cell doses are associated with decreased relapse rates

Peripheral blood stem cells (PBSC) have been increasingly used in the matched unrelated donor (MUD) transplant setting, but the impact of CD34(+) cell dose on outcomes in this setting have not been well characterized. We analyzed 181 consecutive patients who underwent MUD-PBSC transplantation at the City of Hope between August 2000 to December 2004. Patients were conditioned with either full-intensity regimen or reduced-intensity regimen. There was a significant inverse relationship between higher CD34(+) cell dose and faster neutrophil engraftment (r = -0.16, P = .035). By univariate analysis, a CD34(+) cell dose > or =4.2 x 10(6)/kg (above the lowest quartile) was associated with significantly lower relapse risk (hazard ratio [HR] = 0.67, P = .0126), with a trend for corresponding improvement for disease-free survival (HR = 0.84, P = .12) but not overall survival (HR = 0.91, P = .46). The impact of the CD34(+) cell dose remained significant in multivariate analysis. The higher CD34(+) cell dose was significantly associated with faster recovery of absolute lymphocyte counts on day +30 posttransplant. Subset analysis demonstrated that the higher CD34(+) cell dose was associated with (1) greater reduction in relapse in myeloid malignancies than that in lymphoid malignancies, (2) greater reduction in reduced-intensity conditioning than in full-intensity conditioning, (3) greater reduction in relapse when there is a inhibitory killer-cell immunoglobulin-like receptor ligand (iKIRL)-mismatch in the gravft-versus-host (GVH) direction, and (4) greater reduction in relapse when there is a lack of iKIRL, suggesting that the protective effect of CD34(+) cell dose against relapse may be immune-mediated, possibly through NK cell recovery.

Peripheral blood progenitor cell or bone marrow transplantation: controversy remains

PURPOSE OF REVIEW

The paper compares bone marrow and peripheral blood progenitor cell transplantations in the allogeneic setting.

RECENT FINDINGS

Peripheral blood progenitor cell use has emerged as an international standard of care for hematopoietic transplantation. These cells have a different cellular composition including higher numbers of CD34 cells and markedly higher numbers of T lymphocytes. Current data support the general safety of this approach for normal transplant donors. Results consistently indicate more rapid hematopoietic recovery compared with bone marrow transplantation. This may result in improved early survival in adults with high-risk leukemias, but longer follow-up has demonstrated an increased rate of chronic graft-versus-host disease morbidity and mortality which may obviate the long-term benefit.

SUMMARY

It is unclear whether peripheral blood progenitor cell or bone marrow transplantation will produce improved disease-free or overall survival. Additional studies with long-term follow-up are necessary to resolve these controversies.

Cyclosporin, methotrexate and prednisolone for graft-versus-host disease prophylaxis in allogeneic peripheral blood progenitor cell transplants

The utility of GVHD prophylaxis with cyclosporin, MTX and prednisolone (CSA/MTX/Pred) in allogeneic PBPC transplants is not well described although there are published data using this combination after bone marrow transplants. The effectiveness of this regimen on the prevention of GVHD was assessed in 107 consecutive sibling and less-than-ideal donor transplant recipients over a 5-year period and compared to that observed in 65 patients receiving standard CSA and short-course MTX without prednisolone. Oral prednisolone was commenced on day +14 at 0.5 mg/kg per day, increased to 1 mg/kg per day on day +21 to day +34 then gradually tapered and ceased by day +100. The cumulative incidence of acute GVHD (grades II-IV) to day 100 in those receiving prednisolone prophylaxis was lower (52 versus 76%, P<0.01). The onset of symptomatic GVHD requiring systemic treatment was delayed from a median of 41 days post transplant to 92 days. When assessment of the cumulative incidence of symptomatic GVHD continued to day +180 incidence became similar (74 versus 78%), there was no difference between the two groups in rates of relapse, transplant-related mortality, infections or chronic GVHD. We conclude that the addition of prednisolone to CSA/MTX delays the onset of early acute GVHD in PBPC recipients but has no impact on the overall incidence of GVHD.

Risk factors for acute graft-versus-host disease grades II-IV after reduced intensity conditioning allogeneic stem cell transplantation with unrelated donors: a single centre study

We analysed factors associated with moderate to severe acute GVHD in 111 patients treated with fludarabin-based reduced intensity conditioning (RIC) and allogeneic haematopoietic stem cell transplantation (HSCT). Most patients had a haematological malignancy. Donors were 97 HLA-A, -B and -DRbeta1 identical unrelated and 14 HLA-A, -B or -DRbeta1 allele mismatched unrelated donors. In the univariate analysis, we found ten factors associated with acute GVHD. These were diagnosis (P=0.06), GVHD prophylaxis with combinations other than CsA+MTX (P=0.006), graft nucleated (P<0.001) and CD34 (P<0.001) cell-dose, bidirectional ABO mismatch (P=0.001), conditioning (P=0.002), hospital vs home-care (P=0.06), ATG dose (P<0.001), donor herpes virus serology (P=0.07) and an immunized female donor to male recipient (P=0.05). In the multivariate analysis, three factors remained significant: a high CD34 cell dose (P<0.001), low dose (4 mg/kg) ATG (P<0.001), and an immunized female donor to male recipient (P<0.01). Patients receiving a CD34 cell dose > or =17.0 x 10(6) per kg had a higher incidence of GVHD, 53.7%, compared to 22.3% in patients receiving a lower dose (P=0.002). In patients without any of these risk factors (n=70), the incidence of acute GVHD was 14.1%, while it was 38.0 and 85.0% in patients with one (n=29) or two (n=10) risk factors (P<0.001). We concluded that risk factors for acute GVHD using RIC are similar as using myeloablative conditioning.

Peripheral blood grafts from unrelated donors are associated with increased acute and chronic graft-versus-host disease without improved survival

Few studies have tested the benefits of using peripheral blood stem cell (PBSC) grafts versus bone marrow (BM) grafts for unrelated donor transplantation. Yet there has been a substantial change in clinical practice, with increasing numbers of adults receiving unrelated donor PBSC grafts. We compared outcomes after 331 PBSC and 586 BM transplants in adults with leukemia and myelodysplastic syndrome (MDS) who were followed for a median of 3 years after transplantation. PBSC recipients were less likely to have chronic myelogenous leukemia (CML) and more likely to have MDS, to have poor performance scores, and to be transplanted more recently. Outcomes were analyzed using Cox regression models. Rates of grades 2-4 acute graft-versus-host disease (GVHD) (58% versus 45%, P < .001) and chronic GVHD (cGVHD) (56% versus 42%, P < .001) were significantly higher with PBSC than with BM transplants. Rates of grade II-IV aGVHD were similar with PBSC and BM transplants. The 3-year probabilities of treatment-related mortality (TRM), leukemia recurrence, leukemia-free, and overall survival (OS) were similar in the 2 groups with 3-year leukemia-free survival rates of 30% and 32% after transplantation of PBSC and BM, respectively. Unlike results after HLA-matched sibling donor PBSC transplants, we did not identify a survival advantage with PBSC grafts in patients receiving unrelated donor transplants for advanced leukemia. The higher rate of cGVHD after PBSC transplants and, consequently, more frequent late adverse events warrant extended follow up of PBSC recipients.

Similar Outcome After Unrelated Allogeneic Peripheral Blood Stem Cell Transplantation Compared With Bone Marrow in Children and Adolescents

This study compares children and adolescents with hematological malignancies undergoing allogeneic stem cell transplantation (ASCT) with unrelated donors receiving either bone marrow (BM, n=39) or peripheral blood stem cells (PBSCs, n=35). Age and other characteristics were comparable in the two groups. All patients were given conventional conditioning and antithymocyte globulin (ATG). Graft-versus-host disease prophylaxis consisted of cyclosporine plus methotrexate or prednisolone. After PBSC, engraftment of neutrophils and platelets were more rapid. The incidences of acute and chronic graft-versus-host disease were similar in the two groups. In the two groups, other outcome variables, such as transplant-related mortality, overall survival, and relapse-free survival, were the same. Patients given BM tended to have more relapses (P=0.1) and patients given PBSC tended to have more incidences of infectious death. Four cases of EBV-lymphomas were found among patients receiving PBSC, whereas no case was seen in patients given BM (P=0.1). We found no differences in transplant-related mortality and survival in children and adolescents receiving BM or PBSC from unrelated donors. More rapid engraftment and a trend for less relapses in patients given PBSC grafts was noted.

Reduced-intensity conditioning for unrelated donor progenitor cell transplantation: long-term follow-up of the first 285 reported to the national marrow donor program

To determine the long-term outcome of patients undergoing unrelated donor transplantation (URD) after a reduced intensity conditioning (RIC) regimen, we performed a retrospective analysis of the transplant outcomes of the first 5 years of RIC experience as reported to the National Marrow Donor Program (NMDP). Patients were included if they were older than 18 years and had undergone a URD transplant procured through the NMDP from January 1, 1996 until May 31, 2001, with an RIC regimen for a hematologic malignancy. The number of URDs performed using an RIC increased from 59 during 1996 to 1999, to 149 in the year 2000. RIC recipients were older (53 vs. 33 years) and had a higher likelihood of having advanced disease (81% vs. 51%) when compared to patients undergoing a myeloablative conditioning regimen during the same time period. The 5-year survival rate is 23% (95% confidence interval [CI]; 18, 28), whereas the 5 year incidence of progression/relapse is 43.4% (95% CI; 37,49). Prognostic factors for better overall survival on multivariate analysis were earlier disease stage, longer time to transplant from diagnosis, better HLA match, >or=90% performance score, and use of peripheral blood stem cells. This analysis demonstrates that long-term survival and disease control can be obtained with URD progenitor cell transplantation after RIC conditioning. However, only prospective trials will define the optimal role of this therapy in patients with hematologic malignancies. Therefore, URD transplantation with RIC should continue to be explored in the context of clinical trials.

Cytomegalovirus infections following umbilical cord blood transplantation using reduced intensity conditioning regimens for adult patients

Cytomegalovirus (CMV) infection is a major complication after allogeneic hematopoietic stem cell transplantation (Allo-HSCT); however, we have little information on the clinical features of CMV reactivation after cord blood transplantation using reduced-intensity regimens (RI-CBT) for adults. We reviewed medical records of 140 patients who underwent RI-CBT at Toranomon Hospital between January 2002 and March 2005. All the patients were monitored for CMV-antigenemia weekly, and, if turned positive, received preemptive foscarnet or ganciclovir. Seventy-seven patients developed positive antigenemia at a median onset of day 35 (range, 4-92) after transplant. Median of the maximal number of CMV pp65-positive cells per 50,000 cells was 22 (range, 1-1806). CMV disease developed in 22 patients on a median of day 35 (range, 15-106); 21 had enterocolitis and 1 had adrenalitis. CMV antigenemia had not been detected in 2 patients, when CMV disease was diagnosed. CMV disease was successfully treated using ganciclovir or foscarnet in 14 patients. The other 8 patients died without improvement of CMV disease. In multivariate analysis, grade II-IV acute graft-versus-host disease was a risk factor of CMV disease (relative risk 3.48, 95% confidential interval 1.47-8.23). CMV reactivation and disease develop early after RI-CBT. CMV enterocolitis may be a common complication after RI-CBT.

Severe infections after unrelated donor allogeneic hematopoietic stem cell transplantation in adults: comparison of cord blood transplantation with peripheral blood and bone marrow transplantation

We evaluated the occurrence of severe infections in 192 consecutive adult recipients of volunteer unrelated donor allogeneic hematopoietic stem cell transplants, with a detailed analysis of severe infections after receipt of cord blood transplants (CBTs; n = 48) or bone marrow transplants (BMTs)/peripheral blood stem cell transplants (PBSCTs; n = 144). At a 3-year median follow-up, CBT recipients had a higher risk of developing any severe infection (85% versus 69% in BMT/PBSCT recipients, P < .01). CBT recipients had a higher incidence of severe bacterial infections before day +100, but at 3 years the risks of these and other infections were similar in the CBT and BMT/PBSCT groups. In addition, the 100-day and 3-year incidences of infection-related mortality (IRM) did not differ between groups (P = .2 and .5, respectively). In multivariate analysis, the most significant risk factor for IRM in all 192 patients was monocytopenia (.2 x 10(9)/L). In CBT recipients, only neutropenia (.2 x 10(9)/L) on day +30 and low nucleated cell dose infusion (< 2 x 10(7)/kg) showed a trend for increased IRM (P = .05 in both cases). Stem cell source had no effect on day +100 or 3-year nonrelapse mortality (NRM), cytomegalovirus infection, cytomegalovirus disease (7% versus 6%), or overall survival (36% versus 39%, respectively). The number of mismatches in HLA (A, B, and DRB1) had no effect on any outcome in CBT recipients. In contrast, in the BMT/PBSCT group, the presence of any mismatch by low or high-resolution HLA typing (A, B, C, and DRB1) increased NRM and decreased overall survival (P < .01). IRM was the primary or secondary cause of death in 61% and 59% of CBT and BMT/PBSCT recipients who died, respectively. Our results confirm the relevance of severe infectious complications as source of severe morbidity and NRM after volunteer unrelated donor hematopoietic stem cell transplantation in adults, but suggest that CBT recipients have a similar risk of dying from an infection if an accurate selection of a cord blood unit is done.

Allogeneic Stem-Cell Transplantation Using a Reduced-Intensity Conditioning Regimen Has the Capacity to Produce Durable Remissions and Long-Term Disease-Free Survival in Patients With High-Risk Acute Myeloid Leukemia and Myelodysplasia

Purpose

The toxicity of allogeneic stem-cell transplantation can be substantially reduced using a reduced-intensity conditioning (RIC) regimen. This has increased the proportion of patients with myeloid malignancies eligible for allogeneic transplantation. However, the capacity of RIC allografts to produce durable remissions in patients with acute myeloid leukemia (AML) and myelodysplasia (MDS) has not yet been defined, and consequently, the role of RIC allografts in the management of these diseases remains conjectural.

Patients and Methods

Seventy-six patients with high-risk AML or MDS received an allograft using a fludarabine/melphalan RIC regimen incorporating alemtuzumab. The median age of the cohort was 52 years (range, 18 to 71 years).

Results

The 100-day transplantation-related mortality rate was 9%, and no patient developed greater than grade 2 graft-versus-host disease. With a median follow-up of 36 months (range, 13 to 70 months), 27 patients were alive and in remission, with 3-year actuarial overall survival (OS) and disease-free survival (DFS) rates of 41% and 37%, respectively. The 3-year OS and DFS rates of patients with AML in complete remission at the time of transplantation were 48% and 42%, respectively. Disease relapse was the most common cause of treatment failure and occurred at a median time of 6 months after transplantation. All but one patient destined to relapse did so within 24 months of transplantation.

Conclusion

The extended follow-up in this series identifies a high risk of early disease relapse but provides evidence that RIC allografts can produce sustained DFS in a significant number of patients with AML who would be ineligible for allogeneic transplantation with myeloablative conditioning.

Unrelated donor or partially matched related donor peripheral stem cell transplant with CD34+ selection and CD3+ addback for pediatric patients with leukemias

Unmodified peripheral stem cell transplants are associated with an increased risk of extensive chronic GVHD. T depletion may reduce this risk, but the risk of graft failure or relapse may increase. To decrease the risks of both extensive chronic GVHD and graft failure, we added back a defined dose of CD3+ cells to CD34+ selected PSCs. Twenty-four patients were evaluable for outcome analysis. Donors were unrelated (23) or related (1). Conditioning was thiotepa, cyclophosphamide, and total body irradiation. Cyclosporine was used post transplant. Following CD34+ selection, a total of 5 x 10(5)/kg CD3+ cells were infused. Donors were matched for 12 patients. The median CD34+ dose infused was 7.1 x 10(6)/kg. Engraftment occurred in all patients at a median of 14 days (10-19). Twelve patients are alive in remission 15-34 months (median, 25) post PSCT. GVHD occurred in 17 patients, but was >grade II in only 2. Chronic GVHD occurred in 61.5% of evaluable patients, but was limited to skin and perioral cavity. Two patients relapsed, and 10 patients died of non-relapse causes. This study demonstrates that PSCT with CD34+ selection and a defined dose of CD3+ results in prompt engraftment and may limit development of extensive chronic GVHD.

High doses of transplanted CD34+ cells are associated with rapid T-cell engraftment and lessened risk of graft rejection, but not more graft-versus-host disease after nonmyeloablative conditioning and unrelated hematopoietic cell transplantation

This report examines the impact of graft composition on outcomes in 130 patients with hematological malignancies given unrelated donor granulocyte-colony-stimulating-factor-mobilized peripheral blood mononuclear cells (G-PBMC) (n = 116) or marrow (n = 14) transplantation after nonmyeloablative conditioning with 90 mg/m(2) fludarabine and 2 Gy TBI. The median number of CD34(+) cells transplanted was 6.5 x 10(6)/kg. Higher numbers of grafted CD14(+) (P = 0.0008), CD3(+) (P = 0.0007), CD4(+) (P = 0.001), CD8(+) (P = 0.004), CD3(-)CD56(+) (P = 0.003), and CD34(+) (P = 0.0001) cells were associated with higher levels of day 28 donor T-cell chimerism. Higher numbers of CD14(+) (P = 0.01) and CD34(+) (P = 0.0003) cells were associated with rapid achievement of complete donor T-cell chimerism, while high numbers of CD8(+) (P = 0.005) and CD34(+) (P = 0.01) cells were associated with low probabilities of graft rejection. When analyses were restricted to G-PBMC recipients, higher numbers of grafted CD34(+) cells were associated with higher levels of day 28 donor T-cell chimerism (P = 0.01), rapid achievement of complete donor T-cell chimerism (P = 0.02), and a trend for lower risk for graft rejection (P = 0.14). There were no associations between any cell subsets and acute or chronic GVHD nor relapse/progression. These data suggest more rapid engraftment of donor T cells and reduced rejection rates could be achieved by increasing the doses of CD34(+) cells in unrelated grafts administered after nonmyeloablative conditioning.

CD34, CD4, and CD8 cell doses do not influence engraftment, graft-versus-host disease, or survival following myeloablative human leukocyte antigen-identical peripheral blood allografting for hematologic malignancies

OBJECTIVES

Optimal granulocyte colony-stimulating factor-mobilized peripheral blood progenitor cell (G-PBMC) graft compositions for myeloablative allogeneic hematopoietic cell transplantation (AHCT) have not been identified. G-PBMC cell contents were analyzed for influence on outcomes.

PATIENTS AND METHODS

Human leukocyte antigen(HLA)-identical related donor AHCT was used to treat 101 patients with hematologic malignancies at a single institution between 1995 and 2002. CD34+, CD3+, CD4+, and CD8+ cell doses were enumerated by flow cytometry and evaluated by univariate analysis.

RESULTS

Categorized by the median of cell doses infused, no G-PBMC cell dose significantly correlated with neutrophil and platelet engraftment. Incidence of grade II to IV acute graft-versus-host disease (GVHD) was 24.6% (95% confidence interval [CI]: 15.9-33.3) and was not significantly influenced by evaluated G-PBMC cell doses. With a median follow-up time of 18 months for surviving patients, estimates for extensive chronic GVHD was 43.8% (95% CI: 31.4-56.2), for freedom from progression was 69.5% (95% CI: 58.1-80.9), and for overall survival was 46.9% (95% CI: 35.5-58.3). CD34+, CD3+, CD4+, and CD8+ cell doses were not significantly predictive of extensive chronic GVHD, freedom from progression or overall survival. Additionally, comparing patients receiving the upper versus lower 33rd percentiles of CD34+ cell dose, associations with extensive chronic GVHD remained insignificant (p=0.21; relative risk (RR)=1.7; 95% CI: 0.7-3.9).

CONCLUSIONS

G-PBMC graft content does not influence outcomes after myeloablative AHCT. In particular, no significant association between extensive chronic GVHD was identified with any G-PBMC cell dose, including CD34.

Antithymocyte globulin for the prevention of graft-versus-host disease after unrelated hematopoietic stem cell transplantation for acute myeloid leukemia: results from the multicenter German cooperative study group

A total of 155 patients with acute myeloid leukemia (AML) received hematopoietic stem cell transplants from unrelated donors after standard conditioning. Clinical outcome after the use of two different antithymocyte globulins for the prevention of graft-versus-host disease (GvHD) was analyzed in a retrospective study as follows: rabbit ATG (Thymoglobulin Sangstat/Genzyme, n=49, median age 42 years, 53% in CR, further ATG-S); rabbit ATG (ATG-Fresenius, n=38, median age 42 years, 58% in CR, further ATG-F) or no ATG (n=68, median age 36 years, 55% in CR). The groups were comparable regarding disease status at transplant, age, CMV status and cytogenetics. Grade III-IV acute GvHD was found in 15% in the ATG and 27% in the no ATG group (P=0.44). The most important independent risk factors for chronic GvHD (cGvHD) were the use of ATG, disease status at transplant and conditioning. cGvHD developed significantly more frequently in no ATG group. With the median follow-up of 34 months, the 5-year survival is 42% for those transplanted in CR. To conclude, these data demonstrate that the transplants performed in CR, with ATG, are associated with a good outcome, low incidence of cGvHD and no increase of relapse.

Preclinical ex vivo expansion of G-CSF-mobilized peripheral blood stem cells: effects of serum-free media, cytokine combinations and chemotherapy

OBJECTIVES

Ex vivo expansion of granulocyte-colony stimulating factor (G-CSF)-mobilized peripheral blood stem cells (PBSC) is a promising approach for overcoming the developmental delay of bone marrow (BM) reconstitution after transplantation. This project investigated the effects of culture duration, serum-free media, cytokine combinations, and chemotherapy on the outcomes of expansion.

METHODS

Enriched CD34+ cells were cultured for 8 or 10 d in serum-free media (QBSF-60 or X-Vivo 10) and four combinations of cytokines consisting of recombinant human pegylated-megakaryocyte growth and development factor, stem cell factor, flt-3 ligand, G-CSF, interleukin (IL)-6, platelet-derived growth factor (PDGF), and IL-1beta.

RESULTS

Eight days of culture in QBSF-60 significantly supported efficient expansions of CD34+ cells, CD34+ CD38- cells, colony-forming units (CFU) of myeloid, erythroid, megakaryocytic, and mixed lineages to 3.76-, 14.4-, 28.3-, 24.0-, 38.1-, and 15.7-fold, respectively. Whilst PDGF or IL-6 enhanced the expansion of early, myeloid, and erythroid progenitors, IL-1beta specifically promoted the megakaryocytic lineage. Engraftment of human CD45+ cells were detectable in all non-obese diabetic/severe-combined immunodeficient mice transplanted with expanded PBSC from donor samples, being 5.80 +/- 3.34% of mouse BM cells. The expansion and engraftment capacity of CD34+ cells from subjects postchemotherapy were significantly compromised across the panel of progenitor cells.

CONCLUSION

Our results provided an optimized protocol for PBSC expansion, applicable to ameliorating neutropenia and thrombocytopenia in post-BM transplant patients by the prompt provision of progenitor cells. For postchemotherapy patients, expansion products might provide committed progenitors for improving short-term engraftment, but not self-renewable stem cells.