Umbilical cord blood transplantation in adults: results of the prospective Cord Blood Transplantation (COBLT)

Cytomegalovirus Immune reconstitution in cord blood transplant recipients on letermovir prophylaxis

INTRODUCTION

Cytomegalovirus (CMV) can cause significant morbidity and mortality in cord blood transplant (CBT) recipients. Development of CMV-specific cell-mediated immunity (CMV-CMI) has been associated with protection against CMV clinically significant reactivation (CsCMV). In this study, we evaluated CMV-CMI reconstitution during letermovir prophylactic therapy, which prevents CsCMV without complete suppression of CMV reactivation.

METHODS

We measured CMV-CMI in CMV-seropositive CBT recipients pre-transplant after Day+90 of letermovir prophylaxis and at Days +180, and +360- post-transplant using a dual color CMV-specific IFNγ/IL2 FLUOROSpot. CsCMV and nonCsCMV reactivations were abstracted from medical records. CsCMV was defined as CMV viral load ≥5,000 IU/ml using a whole blood assay.

RESULTS

Among 70 CBT recipients, 31 developed CMV-CMI by Day+90 and an additional eight and five participants by Days +180 and +360, respectively. Thirty-eight participants developed CMV reactivation, including nine with CsCMV. Most reactivations (33 of 38) occurred before Day+180. Early CMV-CMI was present in six out of nine participants with CsCMV, indicating a lack of protection against CsCMV. Moreover, the magnitude of CMV-CMI at Day+90 did not differ between participants with CsCMV and nonCsCMV.

CONCLUSION

Approximately 50% of CBT recipients reconstituted CMV-CMI during letermovir prophylactic therapy. However, CMV-CMI did not reach levels protective against CsCMV. Extension of CMV prophylaxis beyond Day+90 may be considered in CMV-seropositive CBT recipients.

Children's Oncology Group's 2023 blueprint for research: Cellular therapy and stem cell transplantation

Since the publication of the last Cellular Therapy and Stem Cell Transplant blueprint in 2013, Children's Oncology Group cellular therapy-based trials advanced the field and created new standards of care across a wide spectrum of pediatric cancer diagnoses. Key findings include that tandem autologous transplant improved survival for patients with neuroblastoma and atypical teratoid/rhabdoid brain tumors, one umbilical cord blood (UCB) donor was safer than two UCB donors, killer immunoglobulin receptor (KIR) mismatched donors did not improve survival for pediatric acute myeloid leukemia when in vivo T-cell depletion is used, and the depth of remission as measured by next-generation sequencing-based minimal residual disease assessment pretransplant was the best predictor of relapse for acute lymphoblastic leukemia. Plans for the next decade include optimizing donor selection for transplants for acute leukemia/myelodysplastic syndrome, using novel engineered cellular therapies to target a wide array of malignancies, and developing better treatments for cellular therapy toxicities such as viral infections and graft-vs-host disease.

The impacts of total body irradiation on umbilical cord blood hematopoietic stem cell transplantation

Background

Umbilical cord blood hematopoietic stem cells are commonly used for hematopoietic system reconstitution in recipients after umbilical cord blood transplantation (UCBT). However, the optimal conditioning regimen for UCBT remains a topic of debate. The exact impact of total body irradiation (TBI) as a part of conditioning regimens remains unknown.

Objectives

The aim of this study was to evaluate the impacts of TBI on UCBT outcomes.

Design

This was a multi-institution retrospective study.

Methods

A retrospective analysis was conducted on the outcomes of 136 patients receiving UCBT. Sixty-nine patients received myeloablative conditioning (MAC), in which 33 underwent TBI and 36 did not, and 67 patients received reduced-intensity conditioning (RIC), in which 43 underwent TBI and 24 did not. Univariate and multivariate analyses were conducted to compare the outcomes and the post-transplant complications between patients who did and did not undergo TBI in the MAC subgroup and RIC subgroup, respectively.

Results

In the RIC subgroup, patients who underwent TBI had superior overall survival (adjusted hazard ratio [aHR] = 0.25, 95% confidence interval [CI]: 0.09-0.66, p = 0.005) and progression-free survival (aHR = 0.26, 95% CI: 0.10-0.66, p = 0.005). However, in the MAC subgroup, there were no statistically significant differences between those receiving and not receiving TBI.

Conclusion

In the setting of RIC in UCBT, TBI utilization can improve overall survival and progression-free survival. However, TBI does not show superiority in the MAC setting.

Umbilical Cord Blood Transplantation: Connecting Its Origin to Its Future

Transplantation of umbilical cord blood (UCB) is an attractive alternative source of hematopoietic stem cells (HSCs). The unique properties of cord blood and its distinct immune tolerance and engraftment kinetics compared to bone marrow (BM) and peripheral blood progenitor cells, permit a wider disparity in human leukocyte antigen levels between a cord blood donor and recipient after an unrelated umbilical cord blood transplant (UCBT). In addition, it is readily available and has a lowered risk of graft-versus-host disease (GvHD), with similar long-term clinical outcomes, compared to BM transplants. However, the relatively low number of cells administered by UCB units, as well as the associated delayed engraftment and immune reconstitution, pose limitations to the wide application of UCBT. Research into several aspects of UCBT has been evaluated, including the ex vivo expansion of cord blood HSCs and the process of fucosylation to enhance engraftment. Additionally, UCB has also been used in the treatment of several neurodegenerative and cardiovascular disorders with varying degrees of success. In this article, we will discuss the biology, clinical indications, and benefits of UCBT in pediatric and adult populations. We will also discuss future directions for the use of cord blood.

Clinical Outcomes of Unrelated Umbilical Cord Blood Graft vs. Haploidentical Donor Transplantation: Critical Issues for an Adequate Comparison

Unrelated umbilical cord blood (UCB) and haploidentical grafts have been used for allogeneic hematopoietic stem and progenitor cell (HSPC) transplantation in patients without a related or non-related human leukocyte antigen (HLA)-matched donor. The less stringent HLA-matching requirement in both sources raises an important possibility for patients in need of urgent transplantation to treat any hematological disease. Selection of the best alternative donor is a difficult task that will depend on donor criteria, center experience, patient disease conditions, and risk, among others. Most comparisons available in scientific publications between both graft sources are obtained from retrospective analysis in wide time windows and a heterogeneous number of patients, types of disease, disease stages, previous treatments, graft source, conditioning regimen, graft vs. host disease (GVHD) approach, and evaluable endpoints. There is also an evident impact of the economic traits since low-income countries must consider less expensive treatments to satisfy the needs of the patients in the most effective possible path. Therefore, haploidentical transplantation could be an appealing option, even though it has not been completely established if any chronic treatment derived from the procedure could become a higher cost. In Colombia, there is a huge experience in UCB transplantation especially in units of pediatric transplantation where benign indications are more common than in adults. Due to the availability of a public UCB bank and HLA high-resolution typing in Colombia, there is a wider inventory of cord blood donors. Unfortunately, we do not have an unrelated bone marrow donor registry, so UCB is an important source along with haploidentical transplantation to consider in decision-making. This minireview focuses on comparing the main issues associated with the use of both HSCP sources and provides tools for physicians who face the difficult decision between these alternative donor sources.

Cytomegalovirus in Haematological Tumours

The exquisite coupling between herpesvirus and human beings is the result of millions of years of relationship, coexistence, adaptation, and divergence. It is probably based on the ability to generate a latency that keeps viral activity at a very low level, thereby apparently minimising harm to its host. However, this evolutionary success disappears in immunosuppressed patients, especially in haematological patients. The relevance of infection and reactivation in haematological patients has been a matter of interest, although one fundamentally focused on reactivation in the post-allogeneic stem cell transplant (SCT) patient cohort. Newer transplant modalities have been progressively introduced in clinical settings, with successively more drugs being used to manipulate graft composition and functionality. In addition, new antiviral drugs are available to treat CMV infection. We review the immunological architecture that is key to a favourable outcome in this subset of patients. Less is known about the effects of herpesvirus in terms of mortality or disease progression in patients with other malignant haematological diseases who are treated with immuno-chemotherapy or new molecules, or in patients who receive autologous SCT. The absence of serious consequences in these groups has probably limited the motivation to deepen our knowledge of this aspect. However, the introduction of new therapeutic agents for haematological malignancies has led to a better understanding of how natural killer (NK) cells, CD4+ and CD8+ T lymphocytes, and B lymphocytes interact, and of the role of CMV infection in the context of recently introduced drugs such as Bruton tyrosine kinase (BTK) inhibitors, phosphoinosytol-3-kinase inhibitors, anti-BCL2 drugs, and even CAR-T cells. We analyse the immunological basis and recommendations regarding these scenarios.

Double unit cord blood transplantation: Who wins-and why do we care?

Double unit cord blood transplantation (DUCBT) has emerged as a successful strategy to improve engraftment and decrease transplant related mortality in adults and large children undergoing cord transplantation. In the vast majority of cases, one unit emerges as the sole source of long term hematopoiesis in the recipient following DUCBT. No factors have been identified that reliably predict which unit will emerge as the dominant unit, and limited studies have examined the mechanism underlying the observation. In a recent publication in Blood, we provide the first compelling data that effector CD8(+) T cells play a critical role in the dominant unit actively rejecting the losing unit. Our findings provide an important first step in understanding the interactions following DUCBT, and provide insights that might be used to optimize graft versus leukemia effect and cord unit selection as well as better understand mechanisms of tolerance.

The influence of temperature treatment before cryopreservation on the viability and potency of cryopreserved and thawed CD34+ and CD45+ cord blood cells

BACKGROUND

Hematopoietic stem cell (HSC) viability and potency is crucial for qualified cord blood (CB) transplants. This study analyzes time and temperature condition before cryopreservation for the viability of CD34⁺/CD45⁺ cells after cryopreservation.

METHODS

Cell viabilities were determined by antibody co-staining with 7-aminoactinomycin D detecting necrotic cells, and subsequent flow cytometric analysis. Additionally, Annexin V staining for determination of apoptotic cells and colony-forming unit (CFU) assays for testing functional potency of HSCs were performed.

RESULTS

For all cell types assessed (CD45⁺/CD34⁺ cells, lymphocytes and granulocytes), the highest viabilities were obtained for CB maintained at 4°C or room temperature (RT; 22 ± 4°C) and cryopreserved directly after collection. Starting material were CB units with an age of 24.7 ± 3.5 h after birth. Post-thaw CD34⁺ cell results were > 90% after temperature treatment of t = 24 h (48 h total age) and > 70% after t = 48 h (72 h total age) at 4°C (48 h, 91.4 ± 5.5%; 72 h, 75.0 ± 12.0%) and RT (48 h, 84.2 ± 9.7%; 72 h, 72.6 ± 0.6%). Viabilities for 30°C samples were < 80% after t = 24 h (48 h total age, 79.8 ± 3.1%) and < 50% after t = 48 h of treatment (72 h total age, 46.8 ± 14.3%). Regarding CFU recovery of pre-freeze (without volume reduction) and thawed CB, a trend toward the highest recoveries was observed at 4°C/RT. The difference between 4°C (77.5 ± 12.0%) and 30°C samples (53.9 ± 4.8%) was shown to be significant in post-thaw samples after t = 24 h treatment (48 h total age; P = 0.0341).

DISCUSSION

Delays between collection and cryopreservation should be minimized because increasing time reduces numbers of viable cells and CFUs before/after cryopreservation. CB units should be maintained at 4°C/RT to retain the highest possible potency of the cells after thawing.

Engineering cord blood to improve engraftment after cord blood transplant

Umbilical cord blood transplant (CBT) has traditionally been associated with slower engraftment of neutrophils, delayed immune reconstitution and consequently higher risk of infections as compared with peripheral blood progenitor cell (PBPC) or bone marrow (BM) transplants. This is primarily due to low numbers of total nucleated cells (TNCs) and the naive nature of CB immune cells. The use of double unit CB transplant (DCBT) increases the total cell dose in the graft, but it still does not produce as rapid engraftment as seen with PBPC or even BM transplants. Herein, we discuss strategies to improve engraftment after CBT. We describe methods of (I) expansion of CB graft ex vivo to increase the total cell dose; and (II) enhancement of BM homing capability of CB progenitor cells; (III) ex vivo expansion of CB derived T cells for improving T cell function against viruses, tumors and protection from graft versus host disease (GVHD). With these novel approaches, engraftment after CBT is now reaching levels comparable to that of other graft types.

From patient centered risk factors to comprehensive prognostic models: a suggested framework for outcome prediction in umbilical cord blood transplantation

Prospectively identifying patients who will gain maximal benefit from umbilical cord blood transplantation (UCBT) with minimal risk is a desirable unmet need. A complex network of parameters related to patient, disease, donor, and procedure all come into play. We review the prognostic role of patient-related risk factors in adults undergoing UCBT. Furthermore, since comprehensive prognostic models are lacking in UCBT, we suggest a framework for integrating patients' features in the development of prediction models for UCBT outcomes. Such models could contribute to patient selection, optimization of the various modifiable features in the process of UCBT, analysis of retrospective data, and design of interventions.

The Impact of High-resolution HLA-A, HLA-B, HLA-C, and HLA-DRB1 on Transplant-related Outcomes in Single-unit Umbilical Cord Blood Transplantation in Pediatric Patients

Current practice for selecting donor units for umbilical cord blood transplant (UCBT) involves matching at HLA-A and HLA-B by low-resolution typing and the HLA-DRB1 allele by high-resolution (HR) typing. We retrospectively studied the impact of HR allele matching at HLA-A, HLA-B, HLA-C, and HLA-DRB1 on transplant-related outcomes in 60 single-unit UCBTs in pediatric patients with malignant and nonmalignant conditions. Five-year overall survival of our cohort was 71% (95% confidence interval, 58-81); 27% experienced primary graft failure. Applying HR typing, donor-recipient mismatch variability increased ranging from 1/8 to 8/8, however, no impact on primary graft failure, graft-versus-host disease or posttransplant infection was observed. UCBTs with ≥6/8 HR matches did have a better overall survival (P=0.04) and decreased transplant-related mortality (P=0.02) compared with <6/8 HR matches. Using standard HLA typing, we showed an increased incidence of acute graft-versus-host disease (grade II to IV) and decreased transplant-related mortality in comparing the matched (6/6) versus ≤5/6 group (P=0.05 and 0.05, respectively). These data support the use of current guidelines for umbilical cord blood selection and encourage utilization of HR typing to select umbilical cord blood units matched at ≥6/8 especially when appropriate ≥5/6 units are available.

Intra-osseous Co-transplantation of CD34-selected Umbilical Cord Blood and Mesenchymal Stromal Cells

Human mesenchymal stromal cells (MSC) have been shown to support the growth and differentiation of hematopoietic stem cells (HSC). We hypothesized that intra-osseous (IO) co-transplantation of MSC and umbilical cord blood (UCB) may be effective in improving early HSC engraftment, as IO transplantation has been demonstrated to enhance UCB engraftment in NOD SCID-gamma (NSG) mice. Following non-lethal irradiation (300rads), 6 groups of NSG mice were studied: 1) intravenous (IV) UCB CD34⁺ cells, 2) IV UCB CD34⁺ cells and MSC, 3) IO UCB CD34⁺ cells, 4) IO UCB CD34⁺ cells and IO MSC, 5) IO UCB CD34⁺ cells and IV MSC, and 6) IV UCB CD34⁺ and IO MSC. Analysis of human-derived CD45⁺, CD3⁺, and CD19⁺ cells 6 weeks following transplant revealed the highest level of engraftment in the IO UCB plus IO MSC cohort. Bone marrow analysis of human CD13 and CD14 markers revealed no significant difference between cohorts. We observed that IO MSC and UCB co-transplantation led to superior engraftment of CD45⁺, CD3⁺ and CD19⁺ lineage cells in the bone marrow at 6 weeks as compared with the IV UCB cohort controls. Our data suggests that IO co-transplantation of MSC and UCB facilitates human HSC engraftment in NSG mice.

Infectious Complications after Umbilical Cord-Blood Transplantation from Unrelated Donors

Umbilical cord-blood (UCB) is a well-recognized alternative source of stem cells for unrelated donor hematopoietic stem cell transplantation (HSCT). As compared with other stem cell sources from adult donors, it has the advantages of immediate availability of cells, absence of risk to the donor and reduced risk of graft-versus-host disease despite donor-recipient HLA disparity. However, the use of UCB is limited by the delayed post-transplant hematologic recovery due, at least in part, to the reduced number of hematopoietic cells in the graft and the delayed or incomplete immune reconstitution. As a result, severe infectious complications continue to be a leading cause of morbidity and mortality following UCB transplantation (UCBT). We will address the complex differences in the immune properties of UCB and review the incidence, characteristics, risk factors, and severity of bacterial, fungal and viral infectious complications in patients undergoing UCBT.

Infusion of CD3/CD28 costimulated umbilical cord blood T cells at the time of single umbilical cord blood transplantation may enhance engraftment

Limited cell numbers in umbilical cord blood (UCB) grafts present a major impediment to favorable outcomes in adult transplantation, largely related to delayed or failed engraftment. The advent of UCB transplantation (UCBT) using two grafts successfully circumvents this obstacle, despite the engraftment of only one unit. Preclinical models suggested that the addition of UCB T cells at the time of transplant can enhance engraftment. We tested whether ex vivo activation by CD3/CD28 costimulation and expansion of T cells from a single UCB graft would be safe and feasible in adults with advanced hematologic malignancies, with an overall objective of optimizing engraftment in single unit UCBT. In this phase 1 study, recipients of single UCB units were eligible if the unit was stored in two adequate fractions. Dose limiting toxicity was defined as grade 3 or grade 4 GVHD within 90 days of UCBT. Four patients underwent UCBT; all were treated at the first dose level (10(5) cells/kg). At the 10(5) cells/kg dose level two subjects experienced grade 3 intestinal GVHD, thus meeting stopping criteria. For three subjects, neutrophil engraftment was early (12, 17, and 20 days), while one subject experienced primary graft failure. We observed early donor T cell trafficking and found that expanded T cells produced supraphysiologic levels of cytokines relevant to engraftment and to lymphoid differentiation and function. Taken together, these preliminary data suggest rapid engraftment in recipients of a single UCBT combined with relatively low doses of activated T cells, though potentially complicated by severe GVHD.

Development and validation of a rapid, aldehyde dehydrogenase bright-based cord blood potency assay

Banked, unrelated umbilical cord blood provides access to hematopoietic stem cell transplantation for patients lacking matched bone marrow donors, yet 10% to 15% of patients experience graft failure or delayed engraftment. This may be due, at least in part, to inadequate potency of the selected cord blood unit (CBU). CBU potency is typically assessed before cryopreservation, neglecting changes in potency occurring during freezing and thawing. Colony-forming units (CFUs) have been previously shown to predict CBU potency, defined as the ability to engraft in patients by day 42 posttransplant. However, the CFU assay is difficult to standardize and requires 2 weeks to perform. Consequently, we developed a rapid multiparameter flow cytometric CBU potency assay that enumerates cells expressing high levels of the enzyme aldehyde dehydrogenase (ALDH bright [ALDH(br)]), along with viable CD45(+) or CD34(+) cell content. These measurements are made on a segment that was attached to a cryopreserved CBU. We validated the assay with prespecified criteria testing accuracy, specificity, repeatability, intermediate precision, and linearity. We then prospectively examined the correlations among ALDH(br), CD34(+), and CFU content of 3908 segments over a 5-year period. ALDH(br) (r = 0.78; 95% confidence interval [CI], 0.76-0.79), but not CD34(+) (r = 0.25; 95% CI, 0.22-0.28), was strongly correlated with CFU content as well as ALDH(br) content of the CBU. These results suggest that the ALDH(br) segment assay (based on unit characteristics measured before release) is a reliable assessment of potency that allows rapid selection and release of CBUs from the cord blood bank to the transplant center for transplantation.

Alternative Donor Transplantation for Acute Myeloid Leukemia

Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative therapy for adult patients with acute myeloid leukemia (AML), but its use for consolidation therapy after first remission with induction chemotherapy used to be limited to younger patients and those with suitable donors. The median age of AML diagnosis is in the late 60s. With the introduction of reduced-intensity conditioning (RIC), many older adults are now eligible to receive allo-HCT, including those who are medically less fit to receive myeloablative conditioning. Furthermore, AML patients commonly have no human leukocyte antigen (HLA)-identical or medically suitable sibling donor available to proceed with allo-HCT. Technical advances in donor matching, suppression of alloreactivity, and supportive care have made it possible to use alternative donors, such as unrelated umbilical cord blood (UCB) and partially HLA-matched related (haploidentical) donors. Outcomes after alternative donor allo-HCT are now approaching the outcomes observed for conventional allo-HCT with matched related and unrelated donors. Thus, with both UCB and haploidentical donors available, lack of donor should rarely be a limiting factor in offering an allo-HCT to adults with AML.

Salvaged single-unit cord blood transplantation for 26 patients with hematologic malignancies not in remission

Treatments for patients with hematologic malignancies not in remission are limited, but a few clinical studies have investigated the effects of salvaged unrelated cord blood transplantation (CBT). We retrospectively studied 19 patients with acute leukemia, 5 with myelodysplastic syndrome (MDS with refractory anemia with excess blasts [RAEB]), and 2 with non-Hodgkin's lymphoma who received 1 CBT unit ≤2 loci human leukocyte antigen (HLA)-mismatched after undergoing myeloablative conditioning regimens between July 2005 and July 2014. All of them were in non-remission before transplantation. The infused total nucleated cell (TNC) dose was 4.07 (range 2.76-6.02)×10⁷/kg and that of CD34⁺ stem cells was 2.08 (range 0.99-8.65)×10⁵/kg. All patients were engrafted with neutrophils that exceeded 0.5×10⁹/L on median day +17 (range 14-37 days) and had platelet counts of >20×10⁹/L on median day +35 (range 17-70 days). Sixteen patients (61.5%) experienced pre-engraftment syndrome (PES), and six (23.1%) patients progressed to acute graft-versus-host disease (GVHD). The cumulative incidence rates of II-IV acute GVHD and chronic GVHD were 50% and 26.9%, respectively. After a median follow-up of 27 months (range 5-74), 14 patients survived and 3 relapsed. The estimated 2-year overall survival (OS), disease-free survival (DFS), and non-relapse mortality (NRM) rates were 50.5%, 40.3%, and 35.2%, respectively. Salvaged CBT might be a promising modality for treating hematologic malignancies, even in patients with a high leukemia burden.

One-unit versus two-unit cord-blood transplantation for hematologic cancers

BACKGROUND

Umbilical-cord blood has been used as the source of hematopoietic stem cells in an estimated 30,000 transplants. The limited number of hematopoietic cells in a single cord-blood unit prevents its use in recipients with larger body mass and results in delayed hematopoietic recovery and higher mortality. Therefore, we hypothesized that the greater numbers of hematopoietic cells in two units of cord blood would be associated with improved outcomes after transplantation.

METHODS

Between December 1, 2006, and February 24, 2012, a total of 224 patients 1 to 21 years of age with hematologic cancer were randomly assigned to undergo double-unit (111 patients) or single-unit (113 patients) cord-blood transplantation after a uniform myeloablative conditioning regimen and immunoprophylaxis for graft-versus-host disease (GVHD). The primary end point was 1-year overall survival.

RESULTS

Treatment groups were matched for age, sex, self-reported race (white vs. nonwhite), performance status, degree of donor-recipient HLA matching, and disease type and status at transplantation. The 1-year overall survival rate was 65% (95% confidence interval [CI], 56 to 74) and 73% (95% CI, 63 to 80) among recipients of double and single cord-blood units, respectively (P=0.17). Similar outcomes in the two groups were also observed with respect to the rates of disease-free survival, neutrophil recovery, transplantation-related death, relapse, infections, immunologic reconstitution, and grade II-IV acute GVHD. However, improved platelet recovery and lower incidences of grade III and IV acute and extensive chronic GVHD were observed among recipients of a single cord-blood unit.

CONCLUSIONS

We found that among children and adolescents with hematologic cancer, survival rates were similar after single-unit and double-unit cord-blood transplantation; however, a single-unit cord-blood transplant was associated with better platelet recovery and a lower risk of GVHD. (Funded by the National Heart, Lung, and Blood Institute and the National Cancer Institute; ClinicalTrials.gov number, NCT00412360.).

Haploidentical vs cord blood transplantation for adults with acute myelogenous leukemia

Hematopoeitic cell transplantation is established as a curative treatment for patients w acute myelogenous leukemia. Haploidentical family donor and umbilical cord blood (UCB) are alternative sources of stem cells for patients lacking a matched sibling or unrelated donor. The early challenges of transplant complications related to poor engraftment and graft-vs-host disease have been overcome with new strategies such as using 2 units and increased cell dose in UCB and T-cell depletion and post transplantation cyclophosphamide in haploidentical transplantation. The outcomes of alternative transplantation for acute leukemia were compared to other traditional graft sources. For patients lacking a matched sibling or unrelated donor, either strategy is a suitable option. The choice should rely mostly on the urgency of the transplantation and the available cell dose as well as the expertise available at the transplant center. This manuscript reviews the options of alternative donor transplantation and highlights recent advances in each of these promising transplantation options.

Similar survival, but better quality of life after myeloablative transplantation using unrelated cord blood vs matched sibling donors in adults with hematologic malignancies

This study included data from 185 consecutively treated patients, 16 years of age or older, who underwent myeloablative transplantation using unrelated umbilical cord blood (UCB) (UCB transplantation (UCBT), n=70) or HLA-identical sibling donor peripheral blood stem cells alone or combined with bone marrow (BMT/PBSCT, n=115) from October 2001 to December 2012. All patients received myeloablative regimens, cyclosporin A plus mycophenolate mofetil as prophylaxis for GVHD, and similar supportive care. Although hematopoietic recovery was significantly delayed after UCBT, the rate of neutrophil engraftment was comparable. The median follow-up was 53 months (range, 15-136 months) for BMT/peripheral blood SCT (PBSCT) recipients and 35 months (range, 10-123 months) for UCBT recipients. There were no significant differences in the cumulative incidence of grades III to IV acute GVHD, relapse rate, or 3-year probabilities of disease-free survival between patients receiving UCBT and those receiving BMT/PBSCT. However, the cumulative incidence of chronic and extensive chronic GVHD was lower in UCBT recipients. The rates of long-term survivors returning to school or work and off immunosuppressive therapy were significantly higher after UCBT, which indicated that long-term survivors who underwent UCBT had a higher quality of life.

Umbilical cord blood transplantation from unrelated donors in patients with Philadelphia chromosome-positive acute lymphoblastic leukemia

There are very few disease-specific studies focusing on outcomes of umbilical cord blood transplantation for Philadelphia chromosome-positive acute lymphoblastic leukemia. We report the outcome of 45 patients with Philadelphia chromosome-positive acute lymphoblastic leukemia who underwent myeloablative single unit cord blood transplantation from unrelated donors within the GETH/GITMO cooperative group. Conditioning regimens were based on combinations of thiotepa, busulfan, cyclophospamide or fludarabine, and antithymocyte globulin. At the time of transplantation, 35 patients (78%) were in first complete remission, four (8%) in second complete remission and six (14%) in third or subsequent response. The cumulative incidence of myeloid engraftment was 96% at a median time of 20 days and significantly better for patients receiving higher doses of CD34(+) cells. The incidence of acute grade II-IV graft-versus-host disease was 31%, while that of overall chronic graft-versus-host disease was 53%. Treatment-related mortality was 17% at day +100 and 31% at 5 years. The 5-year relapse, event-free survival and overall survival rates were 31%, 36% and 44%, respectively. Although the event-free and overall survival rates in patients without BCR/ABL transcripts detectable at time of transplant were better than those in whom BCR/ABL transcripts were detected (46% versus 24% and 60% versus 30%, respectively) these differences were not statistically significant in the univariate analysis (P=0.07). These results demonstrate that umbilical cord blood transplantation from unrelated donors can be a curative treatment for a substantial number of patients with Philadelphia chromosome-positive acute lymphoblastic leukemia.

Myeloablative cord blood transplantation in adults with acute leukemia: comparison of two different transplant platforms

We compared the clinical outcomes of adults with acute leukemia that received single-unit umbilical cord blood transplantation (sUCBT) after conditioning with a busulfan/antithymocyte globulin (BU-ATG)-based regimen at University Hospital La Fe (n = 102) or double-unit UCBT (dUCBT) after conditioning with a total body irradiation (TBI)-based regimen at the University of Minnesota (n = 91). Nonrelapse mortality, relapse and disease-free survival were similar in the 2 groups. Multivariate analyses, showed more rapid neutrophil (hazard ratio [HR], .6; 95% confidence interval [CI], .45 to .80; P = .0006) and platelet recovery (HR, .59; 95% CI, .43 to.83; P = .002) after the BU-ATG-based conditioning and sUCBT. Although there was a lower risk of acute graft-versus-host disease (GVHD) grade II to IV (HR, 2.81; 95% CI, 1.75 to 4.35; P < .001) after BU-ATG and sUCBT, the incidences of grade III to IV acute and chronic GVHD were similar between the 2 groups. Regarding disease-specific outcomes, disease-free survival in both acute myeloid leukemia and acute lymphoblastic leukemia (ALL) patients were not significantly different; however, a significantly lower relapse rate was found in patients with ALL treated with TBI and dUCBT (HR, .3; 95% CI, .12 to .84; P = .02). In the context of these specific treatment platforms, our study demonstrates that sUCB and dUCBT offer similar outcomes.

Cord Blood Transplantation: Can We Make it Better?

Umbilical cord blood is an established source of hematopoietic stem cells for transplantation. It enjoys several advantages over bone marrow or peripheral blood, including increased tolerance for Human Leukocyte Antigen mismatches, decreased incidence of graft-versus-host disease, and easy availability. Unrelated cord blood does have limitations, however, especially in the treatment of adults. In the 24 years since the first umbilical cord blood transplant was performed, significant progress has been made, but delayed hematopoietic engraftment and increased treatment-related mortality remain obstacles to widespread use. Here we summarize the latest results of unrelated cord blood transplants, and review strategies under investigation to improve clinical outcomes.

Cytomegalovirus pneumonia in hematopoietic stem cell recipients

Cytomegalovirus (CMV) is a frequently encountered infection following hematopoietic cell transplantation, and tissue invasive pneumonia is a dreaded complication of the virus in this population. In this review of CMV pneumonia, we address epidemiology, pathogenesis, diagnostics, current therapy, and strategies to prevent the development of CMV. We also review emerging treatment and prevention options for this challenging disease.

Impact of selection of cord blood units from the United States and swiss registries on the cost of banking operations

BACKGROUND

Over the last 2 decades, cord blood (CB) has become an important source of blood stem cells. Clinical experience has shown that CB is a viable source for blood stem cells in the field of unrelated hematopoietic blood stem cell transplantation.

METHODS

Studies of CB units (CBUs) stored and ordered from the US (National Marrow Donor Program (NMDP) and Swiss (Swiss Blood Stem Cells (SBSQ)) CB registries were conducted to assess whether these CBUs met the needs of transplantation patients, as evidenced by units being selected for transplantation. These data were compared to international banking and selection data (Bone Marrow Donors Worldwide (BMDW), World Marrow Donor Association (WMDA)). Further analysis was conducted on whether current CB banking practices were economically viable given the units being selected from the registries for transplant. It should be mentioned that our analysis focused on usage, deliberately omitting any information about clinical outcomes of CB transplantation.

RESULTS

A disproportionate number of units with high total nucleated cell (TNC) counts are selected, compared to the distribution of units by TNC available. Therefore, the decision to use a low threshold for banking purposes cannot be supported by economic analysis and may limit the economic viability of future public CB banking.

CONCLUSIONS

We suggest significantly raising the TNC level used to determine a bankable unit. A level of 125 × 10(7) TNCs, maybe even 150 × 10(7) TNCs, might be a viable banking threshold. This would improve the return on inventory investments while meeting transplantation needs based on current selection criteria.

Umbilical cord blood transplantation: a maturing technology

The use of umbilical cord blood (CB) as a source of hematopoietic progenitor cells for patients with high-risk hematologic disorders receiving allogeneic hematopoietic cell transplantations (HCTs) has increased significantly. Single-institution and registry studies have shown a decreased relapse rate and an increased transplantation-related mortality rate with similar overall survival rates after allogeneic HCT with CB compared with other donor sources. The transplantation of double CB units has overcome the dose limitation inherent in a single CB unit and thus has markedly extended the use of CB to larger children and adults. Similarly, the use of reduced intensity conditioning in the CB transplantation setting has allowed the treatment of older patients who would be unable to tolerate the myeloablative regimens used in the original CB transplantation protocols.

Umbilical cord blood stem cells: clinical trials in non-hematological disorders

BACKGROUND

Umbilical cord blood (UCB) has become the second most common source of stem cells for cell therapy. The recent boom in stem cell research and public fascination with promises of stem cell-based therapies, fueled by the media, have led researchers to explore the potential of UCB stem cells in therapy for non-hematological disorders.

SOURCES OF DATA

ClinicalTrials.gov database searched with key words 'cord blood stem cells' on December 28, 2011.

AREAS OF AGREEMENT

As a rich source of the most primitive hematopoietic stem cells, UCB has a strong regenerative potential in stem cell-based-therapy for hematological disorders.

AREAS OF CONTROVERSY

Potential of UCB stem cells in therapy for non-hematological disorders.

GROWING POINTS

Increasing number of clinical trials with UCB stem cell-based therapy for a variety of diseases.

AREAS TIMELY FOR DEVELOPING RESEARCH

A need for standardization of criteria for selection of UCB units for stem cell-based therapy, outcome measures and long-term follow-up.

Adenovirus-induced interstitial nephritis following umbilical cord blood transplant for chronic lymphocytic leukemia

We present a case of a 27-year-old man who received an unrelated donor umbilical cord blood transplant for chronic lymphocytic leukemia. His postsurgery course was complicated by acute kidney injury, hemorrhagic cystitis, and pancytopenia. Transjugular kidney biopsy showed interstitial nephritis. Viral inclusions were present in tubular epithelial cells, and in situ hybridization studies confirmed the presence of adenovirus. Kidney function improved after a short course of cidofovir. Adenovirus-induced interstitial nephritis should be considered in the differential diagnosis in all cases of interstitial nephritis occurring in immunocompromised patients.

A meta-analysis of unrelated donor umbilical cord blood transplantation versus unrelated donor bone marrow transplantation in acute leukemia patients

Umbilical cord blood has emerged as an alternative stem cell source to bone marrow or peripheral blood stem cells. Umbilical cord blood transplantation (UCBT) is also potentially curative for acute leukemia. However, the effect of unrelated donor bone marrow transplantation (UBMT) and UCBT on the outcome of patients with acute leukemia has not been systematically reviewed. In the present meta-analysis, we systematically searched Cochrane Library, MEDLINE, EMBASE, and CNKI up to May 2011. Two reviewers extracted data independently. Seven studies totaling 3389 patients have been assessed. Pooled results found that the incidence of engraftment failure and transplantation-related mortality were higher in UCBT than in UBMT, and relative risks (RRs) were 4.27 (95% confidence interval [CI], 2.94-6.21) and 1.27 (95% CI, 1.01-1.59), respectively. The rates of acute and chronic graft-versus-host disease (GVHD) in the UCBT group were significantly lower than that in the UBMT group, and RRs were 0.71 (95% CI, 0.65-0.79) and 0.69 (95% CI, 0.52-0.91), respectively. The relapse rate was similar between the UCBT and UBMT group. The leukemia-free survival (LFS) and overall survival (OS) were significantly lower in the UCBT group than in the UBMT group; RRs were 1.14 (95% CI, 1.07-1.22) and hazard ratios (HRs) were 1.31 (95% CI, 1.16-1.48), respectively. Subgroup analysis showed that in patients with acute lymphoblastic leukemia (ALL), the survival was similar between UCBT and UBMT.

Umbilical Cord Blood Transplantation for the Treatment of Hematologic Malignancies

Background

The use of unrelated umbilical cord blood (UCB) has grown as an allogeneic source of hematopoietic cells for transplantation of patients with hematologic malignancies. As the number of UCB transplantation procedures has grown, an increasing number of publications have focused on disease-specific outcomes.

Methods

This review focuses on the outcome data following UCB transplantation in subsets of hematologic malignancies in which experience with this graft source is greater.

Results

Registry and single-institution reports regarding the outcomes of children and adults with acute leukemias after UCB transplantation include many patients, while data on the clinical outcomes of other leukemias are limited due in part to the small number of patients with these diseases. UCB is now routinely used as a source of hematopoietic stem cells (HSCs) in pediatric allogeneic transplantation when a suitable sibling donor is not available. Data also support the use of UCB as an alternative source of HSC for transplantation of patients with hematologic malignancies who lack a more conventional donor. Current data also support UCB for patients who require an allograft in the setting of prospective clinical trials.

Conclusions

Along with safety and feasibility in UCB transplantation, continued study is needed that focuses on issues such as accelerating engraftment, extending access, ensuring quality, and examining outcomes in specific subgroups of patients.

Intensive strategy to prevent CMV disease in seropositive umbilical cord blood transplant recipients

Seropositive umbilical cord blood transplant (UCBT) recipients are at increased risk for CMV complications. To reduce CMV complications, we adopted an intensive strategy that consisted of ganciclovir administered before transplantation (5 mg/kg intravenously daily from day -8 to day -2), high-dose acyclovir (2 g, 3 times daily) after transplantation, and biweekly monitoring with a serum CMV PCR for preemptive therapy. Hazard rates and cumulative incidence of CMV complications along with days treated were compared in high-risk CMV-seropositive UCBT recipients who received the intensive strategy and a historical cohort who received a standard strategy. Of 72 seropositive patients, 29 (40%) received standard prophylaxis and 43 (60%) the new intensive approach. The hazard rate (HR) for CMV reactivation was lower for patients receiving the intensive strategy (HR 0.27, 95% confidence interval 0.15-0.48; P < .001) and led to fewer cases of CMV disease by 1 year (HR 0.11, 95% confidence interval 0.02-0.53; P = .006). In patients who reactivated, the intensive strategy also led to fewer days on CMV-specific antiviral therapy (median 42% [interquartile range 21-63] vs 70% [interquartile range 54-83], P < .001). Use of an intensive CMV prevention strategy in high-risk CMVseropositive UCBT recipients results in a significant decrease in CMV reactivation and disease.

Activated T cells from umbilical cord blood armed with anti-CD3 × anti-CD20 bispecific antibody mediate specific cytotoxicity against CD20+ targets with minimal allogeneic reactivity: a strategy for providing antitumor effects after cord blood transplants

BACKGROUND

In this study, we asked whether anti-CD3-activated T cells (ATCs) from cord blood (CB) could be expanded and targeted to solid tumors or hematologic malignancies for infusions after unrelated CB stem cell transplant and whether cord blood ATCs (CBATCs) could reduce alloresponsiveness.

STUDY DESIGN AND METHODS

CB mononuclear cells (MNCs) were activated with anti-CD3 (20 ng/mL) and expanded for 14 days in interleukin-2 (100 IU/mL). CBATCs were armed with anti-CD3 × anti-CD20 (CD20Bi) or anti-CD3 × anti-Her2 (Her2Bi) bispecific antibodies (CBaATCs) and tested for specific cytotoxicity, cytokine secretion, and alloresponsiveness.

RESULTS

Our results show the mean expansion of CBATCs to be 37-fold after 14 days of culture from either frozen (n=4) or fresh (n=4) CB units. Cytotoxicity was optimal when CBATCs were armed with 50 ng of CD20Bi/10(6) cells. Cytotoxicity peaked between Day 8 and Day 10 for both bispecific antibodies. At an effector-to-target ratio of 25:1, the mean cytotoxicities of CBATCs armed with Her2Bi or CD20Bi were 40% (n=4) and 30% (n=4), respectively. CBaATCs exhibited peak specific interferon-γ enzyme-linked immunosorbent spots on Day 10. CBATCs and CBaATCs suppressed responsiveness to alloantigens by 20% to 50% when compared with normal allogeneic peripheral blood MNC response.

CONCLUSION

We showed that armed CBATCs mediate specific cytotoxicity, secrete low levels of cytokines and chemokines, and demonstrate attenuated response to alloantigens.

An overview of the progress on double umbilical cord blood transplantation

Umbilical cord blood transplantation has been increasingly used over the past years for both malignant and non-malignant hematologic and other diseases as an alternative to mismatched-related or matched-unrelated bone marrow or peripheral blood hematopoietic stem cell transplantation. A disadvantage of cord blood is its low cell content which limits cord blood transplantation to generally low weight recipients, such as children. Various alternatives have been used to overcome this limitation, including co-infusion of two partially HLA-matched cord blood units. According to Eurocord Registry data, this strategy has been applied in approximately 993 adult patients with hematologic diseases since the first double umbilical cord blood transplantation in 1999. In fact, since 2005, the number of adult patients receiving double umbilical cord blood transplantation has surpassed the number of adults transplanted with single cord blood units. The engraftment rate is comparable for both single and double umbilical cord blood transplantation, although the latter is accompanied by a higher incidence of grade II acute graft-versus-host disease and lower leukemia relapse for patients in first complete remission. In the majority of patients undergoing double umbilical cord blood transplantation, transient chimerism, due to the presence of cells from both donor units early post transplant, is replaced by sustained dominance of one unit from which long-term hematopoiesis is derived. Although the biology and the factors that determine unit dominance have not been clarified, the implication of immune-mediated mechanisms has been reported. Preliminary data have demonstrated the safety of double umbilical cord blood transplantation. Ongoing clinical trials and prolonged follow up of the patients will clarify the immunology and determine the efficacy of this approach. We present here a brief overview of the clinical experience on double umbilical cord blood transplantation and its underlying biology.

Umbilical cord blood: biology and transplantation

Umbilical cord blood transplantation is becoming an acceptable alternative source of hematopoietic stem cells for patients with malignant diseases. Cord blood differs from bone marrow and peripheral blood progenitors in its immune tolerance and kinetics of engraftment. In this article, we will review the biology of cord blood stem cells and clinical studies of cord blood transplants in pediatric and adult populations. We will also discuss potential uses of cord blood stem cells in regenerative medicine and novel methods for ex vivo expansion of hematopoietic stem cells. As we learn more about cord blood transplants, there is the potential to overcome the limitations of cord blood transplants so that they can become more widely available.

Cord blood transplants: one, two or more units?

PURPOSE OF REVIEW

This review summarizes the current status of double-unit cord blood transplantation (CBT) to improve engraftment, reduce transplant-related mortality, and improve disease-free survival.

RECENT FINDINGS

Transplantation of cord blood provides a potentially curative therapy for many patients without a suitably human leukocyte antigen-matched related or unrelated donor. Single-unit CBT outcomes have been compromised, however, in adults and larger children by limited cell dose. The introduction of double-unit CBT has improved engraftment and transplant-related mortality in adult patients transplanted for hematologic malignancies, with recent data also suggesting a protection against relapse. These improved outcomes are seen despite only a single unit being responsible for sustained donor hematopoiesis in nearly all patients. The study of double-unit CBT provides unique insights into transplant biology, with emerging data suggesting unit dominance is related to unit viability and unit-versus-unit immune interactions. Multiple unit CBT further serves as a platform to test novel graft manipulations.

SUMMARY

The development of double-unit CBT now allows the majority of patients, regardless of size or racial/ethnic background, access to transplant therapy. Ongoing investigation will serve to further improve outcomes and expand the role of CBT in the future.

Adult dual umbilical cord blood transplantation using myeloablative total body irradiation (1350 cGy) and fludarabine conditioning

High treatment-related mortality (TRM) and high graft failure rate are serious concerns in HLA-mismatched umbilical cord blood (UCB) transplantation with myeloablative conditioning. We conducted a prospective trial of dual UCB transplantation using modified myeloablation consisting of total-body irradiation (TBI; 1350 cGy) and fludarabine (Flu) (160 mg/m(2)). Twenty-seven patients (median age, 33 years; range: 20-58 years) with hematologic malignancies were enrolled. The median combined cryopreserved total nucleated cell (TNC) dose was 4.3 × 10(7)/kg (range: 3.2-7.7 × 10(7)/kg). The cumulative incidences of neutrophil (≥500/μL) and platelet (≥50,000/μL) engraftment were 80% (95% confidence interval [CI], 58%-91%) and 68% (95% CI, 46%-83%), respectively. Among engrafted patients, a single cord blood unit was predominant by 100 days posttransplantation. A higher cryopreserved and infused TNC dose and infused CD3(+) cell dose were significant factors associated with the predominant UCB unit (P = .032, .020, and .042, respectively). TRM and relapse rates at 2 years were 28% (95% CI, 12%-47%) and 20% (95% CI, 7%-37%), respectively. Cumulative incidences of grades II-IV and grades III-IV acute graft-versus-host disease (aGVHD) were 37% (95% CI, 20%-55%) and 11% (95% CI, 3%-26%), respectively, and that of chronic GVHD was 31% (95% CI, 15%-49%). With a median follow-up of 23 months, overall survival and disease-free survival rates at 2 years were 58% (95% CI, 34%-75%) and 52% (95% CI, 29%-70%), respectively. This study supports the use of TBI 1350 cGy/Flu as an alternative to conventional myeloablative conditioning for dual UCB transplantation.

Progenitor cell dose determines the pace and completeness of engraftment in a xenograft model for cord blood transplantation

Two critical concerns in clinical cord blood transplantation are the initial time to engraftment and the subsequent restoration of immune function. These studies measured the impact of progenitor cell dose on both the pace and strength of hematopoietic reconstitution by transplanting nonobese diabetic/severe combined immunodeficiency/interleukin-2 receptor-gamma-null (NSγ) mice with lineage-depleted aldehyde dehydrogenase-bright CD34(+) human cord blood progenitors. The progress of each transplant was monitored over an extended time course by repeatedly analyzing the peripheral blood for human hematopoietic cells. In vivo human hematopoietic development was complete. After long-term transplantation assays (≥ 19 weeks), human T-cell development was documented within multiple tissues in 16 of 32 NSγ mice. Human T-cell differentiation was active within NSγ thymuses, as documented by the presence of CD4(+) CD8(+) T-cell progenitors as well as T-cell receptor excision circles. It is important to note that although myeloid and B-cell engraftment was detected as early as 4 weeks after transplantation, human T-cell development was exclusively late onset. High progenitor cell doses were associated with a robust human hematopoietic chimerism that accelerated both initial time to engraftment and subsequent T-cell development. At lower progenitor cell doses, the chimerism was weak and the human hematopoietic lineage development was frequently incomplete.

Characterization of long-term mixed donor-donor chimerism after double cord blood transplantation

Double cord blood transplantation (DCBT) with two matched or partially matched cord blood units has been implemented successfully to circumvent the limitations of graft cell dose associated with single CBT. After DCBT, sustained haematopoiesis is derived almost exclusively from only one of the donated units. None the less, we previously observed two of six evaluable DCBT patients still having mixed donor-donor chimerism at 28 and 45 months post-transplantation, respectively. In the present study we utilize flow cytometry techniques to perform the first thorough analysis of phenotype and functionality of cord blood units in patients with mixed donor-donor chimerism. Our results suggest that the two stable cord blood units are different phenotypically and functionally: one unit shows more naive T cells, lower T cell cytokine production and higher frequencies of natural killer cells, the other shows higher frequencies of well-differentiated and functional lymphocytes. Additionally, in comparison with control patients having a single prevailing cord blood unit, the patients with donor-donor chimerism exhibit less overall T cell cytokine production and a smaller fraction of memory T cells. Furthermore, our results indicate that human leucocyte antigen-C match of donor units may partly explain the development of a donor-donor mixed chimerism.

Factors affecting mortality following myeloablative cord blood transplantation in adults: a pooled analysis of three international registries

A retrospective analysis was conducted to examine factors affecting early mortality after myeloablative, single-unit cord blood transplantation (CBT) for hematological malignancies in adolescents and adults. Data were collected from the three main CBT registries pooling 514 records of unrelated, single, unmanipulated, first myeloablative allogeneic CBTs conducted in North America or Europe from 1995 to 2005, with an HLA match ≥ 4/6 loci, in patients aged 12-55. Overall 100-day, 180-day and 1-year survival (Kaplan-Meier method) were 56, 46 and 37%, respectively, with no significant heterogeneity across registries. Multivariate analysis showed cell dose < 2.5 × 10⁷/kg (odds ratio (OR) 2.76, P < 0.0001), older age (P = 0.002), advanced disease (P = 0.02), positive CMV sero-status (OR 1.37 P = 0.11), female gender (OR 1.43, P = 0.07) and limited CBT center experience (< 10 records contributed, OR 2.08, P = 0.0003) to be associated with higher 100-day mortality. A multivariate model predictive of 1-year mortality included similar prognostic factors except female gender. Transplant year did not appear as a significant independent predictor. This is the first analysis to pool records from three major CBT registries in the United States and Europe. In spite of some differences in practice patterns, survival was remarkably homogeneous. The resulting model may contribute to better understanding factors affecting CBT outcomes.

Extending cord blood transplant to adults: dealing with problems and results overall

The development of newer strategies to overcome, in particular, the cell dose limitation, has increased the availability of umbilical cord blood (UCB) as a source of hematopoietic stem cells (HSC) for transplantation of adults. Among these strategies is the development of the double UCB, ex vivo, and reduced-intensity transplantation platforms. Several ongoing registry-based and single-institution and multicenter clinical trials are investigating ways to make UCB transplantation safer and to improve the outcomes of adults after UCB transplantation. We review the background data and promising newer strategies that will further expand the utilization of UCB for the treatment of adults.

Clinical expansion of cord blood-derived T cells for use as donor lymphocyte infusion after cord blood transplantation

Allogeneic stem cell transplantation (SCT) from cord blood (CB) as a stem cell source is a promising alternative when no human leukocyte antigen-matched donor is found. Donor lymphocyte infusion (DLI) is a possible treatment modality for threatening graft failure or relapse of an underlying malignancy after transplantation. Ethical and logistical reasons limit the possibility of DLI in the setting of CB SCT. To remedy this restriction, we performed expansion of donor T cells in vitro from CB grafts in a clinical setting for use as future DLI and characterized the expanded cells in comparison to T cells from CB acquired ex vivo and adult peripheral blood. T cells were expanded from grafts used for transplantation, upon CD3/CD28 crosslinking and culture in interleukin-2. Phenotype and function of T cells were assessed by flow cytometry and mixed lymphocyte culture assays. T-cell receptor repertoire distribution was evaluated with polymerase chain reaction-based spectratyping. We were able to amplify T cells to sufficient amounts for DLI in 13 out of 13 initiated expansions. Expanded T cells presented with an activated phenotype and could be induced to produce cytokines by a nonspecific stimulus. When exposed to allogeneic targets, expanded CB T cells proliferated at comparable levels to their ex vivo and adult blood counterparts. In summary, clinical expansion of CB T cells for DLI is feasible and may be a future modality for treatment of graft failure or relapse after SCT.

Cord blood transplantation for haematological malignancies: conditioning regimens, double cord transplant and infectious complications

Growing evidence supports the efficacy of cord blood transplantation (CBT) to treat patients with haematological malignancies, and the number of CBTs is rapidly increasing. Herein, we review considerations regarding conditioning regimens for CBT, the impact of double unit transplantation on CBT outcomes, and data regarding infectious complications following CBT.

Clearance of CMV viremia and survival after double umbilical cord blood transplantation in adults depends on reconstitution of thymopoiesis

Umbilical cord blood grafts are increasingly used as sources of hematopoietic stem cells in adults. Data regarding the outcome of this approach in adults are consistent with delayed and insufficient immune reconstitution resulting in high infection-related morbidity and mortality. Using cytomegalovirus (CMV)-specific immunity as a paradigm, we evaluated the status, mechanism, and clinical implications of immune reconstitution in adults with hematologic malignancies undergoing unrelated double unit cord blood transplantation. Our data indicate that CD8(+) T cells capable of secreting interferon-gamma (IFN-gamma) in a CMV-specific enzyme-linked immunosorbent spot (ELISpot) assay are detectable at 8 weeks after transplantation, before reconstitution of thymopoiesis, but fail to clear CMV viremia. Clearance of CMV viremia occurs later and depends on the recovery of CD4(+)CD45RA(+) T cells, reconstitution of thymopoiesis, and attainment of T-cell receptor rearrangement excision circle (TREC) levels of 2000 or more copies/mug DNA. In addition, overall survival was significantly higher in patients who displayed thymic regeneration and attainment of TREC levels of 2000 or more copies/mug DNA (P = .005). These results indicate that reconstitution of thymopoiesis is critical for long-term clinical outcome in adult recipients of umbilical cord blood transplant. The trial was prospectively registered at http://www.clinicaltrials.gov (NCT00133367).