Single versus double unrelated umbilical cord blood units for allogeneic transplantation in adults with advanced haematological malignancies: a retrospective comparison of outcomes

Decellularized Wharton jelly matrix: a biomimetic scaffold for ex vivo hematopoietic stem cell culture

Hematopoietic stem progenitor cells (HSPCs) reside in the bone marrow (BM) hematopoietic "niche," a special 3-dimensional (3D) microenvironment that regulates HSPC self-renewal and multipotency. In this study, we evaluated a novel 3D in vitro culture system that uses components of the BM hematopoietic niche to expand umbilical cord blood (UCB) CD34⁺ cells. We developed this model using decellularized Wharton jelly matrix (DWJM) as an extracellular matrix (ECM) scaffold and human BM mesenchymal stromal cells (MSCs) as supporting niche cells. To assess the efficacy of this model in expanding CD34⁺ cells, we analyzed UCB CD34⁺ cells, following culture in DWJM, for proliferation, viability, self-renewal, multilineage differentiation, and transmigration capability. We found that DWJM significantly expanded UCB HSPC subset. It promoted UCB CD34⁺ cell quiescence, while maintaining their viability, differentiation potential with megakaryocytic differentiation bias, and clonogenic capacity. DWJM induced an increase in the frequency of c-kit⁺ cells, a population with enhanced self-renewal ability, and in CXCR4 expression in CD34⁺ cells, which enhanced their transmigration capability. The presence of BM MSCs in DWJM, however, impaired UCB CD34⁺ cell transmigration and suppressed CXCR4 expression. Transcriptome analysis indicated that DWJM upregulates a set of genes that are specifically involved in megakaryocytic differentiation, cell mobility, and BM homing. Collectively, our results indicate that the DWJM-based 3D culture system is a novel in vitro model that supports the proliferation of UCB CD34⁺ cells with enhanced transmigration potential, while maintaining their differentiation potential. Our findings shed light on the interplay between DWJM and BM MSCs in supporting the ex vivo culture of human UCB CD34⁺ cells for use in clinical transplantation.

Single- Versus Double-Unit Umbilical Cord Blood Transplantation for Hematologic Diseases: A Systematic Review

Controversial results exist regarding the clinical benefits of single- vs double-unit umbilical cord blood transplantation (UCBT) in patients with hematologic diseases. A systematic review was conducted to evaluate this issue. The PubMed, Embase, and Cochrane Library databases were searched up to May 2018. A total of 25 studies including 6571 recipients were identified. Although double-unit UCB contained higher doses of total nucleated cells and CD34⁺ cells, it offered no advantages over single-unit UCB in terms of hematologic recovery, including the rate and speed of neutrophil and platelet engraftment. Double-unit UCBT was associated with higher incidences of grades II-IV acute and extensive chronic graft-vs-host disease, accompanied by a lower relapse incidence, which may be attributed to a graft-vs-graft effect induced by double-unit UCB. However, transplant-related mortality, disease-free survival, and overall survival were comparable between single- and double-unit UCBT. Although double-unit UCBT confers no clinical advantages over single-unit UCBT, certain patients, such as those at high risk of relapse, might benefit from double-unit UCBT, a possibility that needs to be clarified in future randomized trials.

Erythropoietin modulation is associated with improved homing and engraftment after umbilical cord blood transplantation

Umbilical cord blood (UCB) engraftment is in part limited by graft cell dose, generally one log less than that of bone marrow (BM)/peripheral blood (PB) cell grafts. Strategies toward increasing hematopoietic stem/progenitor cell (HSPC) homing to BM have been assessed to improve UCB engraftment. Despite recent progress, a complete understanding of how HSPC homing and engraftment are regulated is still elusive. We provide evidence that blocking erythropoietin (EPO)-EPO receptor (R) signaling promotes homing to BM and early engraftment of UCB CD34⁺ cells. A significant population of UCB CD34⁺ HSPC expresses cell surface EPOR. Exposure of UCB CD34⁺ HSPC to EPO inhibits their migration and enhances erythroid differentiation. This migratory inhibitory effect was reversed by depleting EPOR expression on HSPC. Moreover, systemic reduction in EPO levels by hyperbaric oxygen (HBO) used in a preclinical mouse model and in a pilot clinical trial promoted homing of transplanted UCB CD34⁺ HSPC to BM. Such a systemic reduction of EPO in the host enhanced myeloid differentiation and improved BM homing of UCB CD34⁺ cells, an effect that was overcome with exogenous EPO administration. Of clinical relevance, HBO therapy before human UCB transplantation was well-tolerated and resulted in transient reduction in EPO with encouraging engraftment rates and kinetics. Our studies indicate that systemic reduction of EPO levels in the host or blocking EPO-EPOR signaling may be an effective strategy to improve BM homing and engraftment after allogeneic UCB transplantation. This clinical trial was registered at www.ClinicalTrials.gov (#NCT02099266).

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.

Outcomes of Cord Blood Transplantation Using Reduced-Intensity Conditioning for Chronic Lymphocytic Leukemia: A Study on Behalf of Eurocord and Cord Blood Committee of Cellular Therapy and Immunobiology Working Party, Chronic Malignancies Working Party of the European Society for Blood and Marrow Transplantation, and the Societé Française de Greffe de Moelle et Therapie Cellulaire

Outcomes after umbilical cord blood transplantation (UCBT) for chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) are unknown. We analyzed outcomes of 68 patients with poor-risk CLL/SLL who underwent reduced-intensity (RIC) UCBT from 2004 to 2012. The median age was 57 years and median follow-up 36 months; 17 patients had del 17p/p53mutation, 19 patients had fludarabine-refractory disease, 11 relapsed after autologous stem cell transplantation, 8 had diagnosis of prolymphocytic leukemia, 4 had Richter syndrome, and 8 underwent transplantation with progressive or refractory disease. The most common RIC used was cyclophosphamide, fludarabine, and total body irradiation (TBI) in 82%; 15 patients received antithymocyte globulin. Most of the cord blood grafts were HLA mismatched and 76% received a double UCBT. Median total nucleated cells collected was 4.7 × 10(7)/kg. The cumulative incidences (CI) of neutrophil and platelet engraftment were 84% and 72% at 60 and 180 days respectively; day 100 graft-versus-host disease (GVHD) (grade II to IV) was 43% and 3-year chronic GVHD was 32%. The CI of relapse, nonrelapse mortality, overall survival, and progression-free survival (PFS) at 3 years were 16%, 39%, 54%, and 45%, respectively. Fludarabine-sensitive disease at transplantation and use of low-dose TBI regimens were associated with acceptable PFS. In conclusion, use of RIC-UCBT seems to be feasible in patients with poor-risk CLL/SLL and improved outcomes were observed in patients with fludarabine-sensitive disease who received low-dose TBI regimens.

Haploidentical bone marrow transplants for haematological malignancies using non-myeloablative conditioning therapy and post-transplant immunosuppression with cyclophosphamide: results from a single Australian centre

AIMS

To demonstrate safety and efficacy of haploidentical bone marrow transplantation with non-myeloablative conditioning and high-dose post-transplant cyclophosphamide in adult patients with leukaemia or lymphoma.

BACKGROUND

Human leukocyte antigen haploidentical bone marrow transplantation is a treatment option in patients with haematological malignancies who have no available human leukocyte antigen-matched donor but is limited by conditioning regimen toxicity, graft failure, relapse and graft-versus-host disease (GvHD).

METHODS

Twelve patients, median age of 51 years, underwent transplantation with T cell replete bone marrow from a haplotype-matched relative. The conditioning regimen consisted of cyclophosphamide, fludarabine and low-dose total body irradiation. Post-transplant immunosuppression consisted of a single dose of cyclophosphamide 50 mg/kg on day 3, followed by oral tacrolimus and mycophenolate mofetil. Outcomes reported are overall survival, engraftment and chimerism, toxicity, and clinical outcome.

RESULTS

All patients had neutrophil recovery (median 14.5 days), and 11 of 12 had platelet engraftment (median 17 days). Two patients had autologous reconstitution. Seven of nine assessable patients had complete donor chimerism. Four patients had grades II-III GvHD, and none had grade IV GvHD. Four patients developed limited stage chronic GvHD. Five patients with acute myeloid leukaemia relapsed. Two patients died of nonrelapse causes, both from other malignancies, and five patients remain alive and relapse free. Median overall survival was 324 days (range 88-1163).

CONCLUSION

This regimen is feasible and well tolerated in older patients with high-risk leukaemia or lymphoma, with minimal short-term toxicity and low rates of GvHD. The proportion of disease-free survivors indicates a graft-versus-malignancy effect is present in survivors.

Double umbilical cord blood transplantation for hematological malignancies: a long-term analysis from the SFGM-TC registry

Allogeneic hematopoietic stem cell (HSC) transplantation is a curative treatment for many hematologic malignancies for which umbilical cord blood (UCB) represents an alternative source of HSCs. To overcome the low cellularity of one UCB unit, double UCB transplantation (dUCBT) has been developed in adults. We have analyzed the outcome of 136 patients who underwent dUCBT reported to the SFGM-TC registry between 2005 and 2007. Forty-six patients received myeloablative regimens, and 90 patients received reduced-intensity conditioning regimens. There were 84 cases of leukemia, 17 cases of non-Hodgkin lymphoma, 11 cases of myeloma, and 24 other hematologic malignancies. At transplantation, 40 (29%) patients were in complete remission. At day 60 after transplantation, the cumulative incidence of neutrophil recovery was 91%. We observed one UCB unit domination in 88% of cases. The cumulative incidence of day 100 acute graft-versus-host disease, chronic graft-versus-host disease, transplant-related mortality, and relapse at 2 years were 36%, 23%, 27%, and 28% respectively. After a median follow-up of 49.5 months, the 3-year probabilities of overall and progression-free survival were 41% and 35%, respectively, with a significant overall survival advantage when male cord engrafted male recipients. We obtained a long-term plateau among patients in complete remission, which makes dUCBT a promising treatment strategy for these patients.

Cord-blood engraftment with ex vivo mesenchymal-cell coculture

BACKGROUND

Poor engraftment due to low cell doses restricts the usefulness of umbilical-cord-blood transplantation. We hypothesized that engraftment would be improved by transplanting cord blood that was expanded ex vivo with mesenchymal stromal cells.

METHODS

We studied engraftment results in 31 adults with hematologic cancers who received transplants of 2 cord-blood units, 1 of which contained cord blood that was expanded ex vivo in cocultures with allogeneic mesenchymal stromal cells. The results in these patients were compared with those in 80 historical controls who received 2 units of unmanipulated cord blood.

RESULTS

Coculture with mesenchymal stromal cells led to an expansion of total nucleated cells by a median factor of 12.2 and of CD34+ cells by a median factor of 30.1. With transplantation of 1 unit each of expanded and unmanipulated cord blood, patients received a median of 8.34×10(7) total nucleated cells per kilogram of body weight and 1.81×10(6) CD34+ cells per kilogram--doses higher than in our previous transplantations of 2 units of unmanipulated cord blood. In patients in whom engraftment occurred, the median time to neutrophil engraftment was 15 days in the recipients of expanded cord blood, as compared with 24 days in controls who received unmanipulated cord blood only (P<0.001); the median time to platelet engraftment was 42 days and 49 days, respectively (P=0.03). On day 26, the cumulative incidence of neutrophil engraftment was 88% with expansion versus 53% without expansion (P<0.001); on day 60, the cumulative incidence of platelet engraftment was 71% and 31%, respectively (P<0.001).

CONCLUSIONS

Transplantation of cord-blood cells expanded with mesenchymal stromal cells appeared to be safe and effective. Expanded cord blood in combination with unmanipulated cord blood significantly improved engraftment, as compared with unmanipulated cord blood only. (Funded by the National Cancer Institute and others; ClinicalTrials.gov number, NCT00498316.).

Cord blood transplantation in Western Australia

BACKGROUND/AIMS

Thirty-one umbilical cord blood transplants performed in Western Australia were retrospectively examined in order to document local experience and relevant prognostic factors. Three cord units were from human leucocyte antigen-matched siblings and the remainder were unrelated single (n= 22) or double (n= 6) cord blood transplants.

METHODS

Twenty patients were transplanted for malignant conditions and 11 for non-malignant conditions. Cord units contained a median of 5.6 × 107 total nucleated cells/kg and 1.4 × 105 CD34+ cells/kg. Cumulative incidence of neutrophil engraftment was 76% at day 60.

RESULTS

Of those who did not engraft, two patients remain alive following subsequent allogeneic bone marrow transplant. There were no deaths caused by graft-versus-host disease. Overall survival at median follow up of 28 months was 62%. Two year overall survival was influenced by type of disease (non-malignant = 91 ± 9% vs malignant = 41 ± 13%, P= 0.005), total nucleated cell dose (>3.5 × 107/kg = 87 ± 9% vs <3.5 × 107/kg = 34 ± 15%, P= 0.01) and CD34 dose (>1.7 × 105/kg = 92% vs <1.7 × 105/kg = 46%, P= 0.04). Age and human leucocyte antigen match did not influence survival. Four relapses occurred, all of which were fatal.

CONCLUSION

Cord blood transplantation for malignant and non-malignant disease is practised in Western Australia and outcomes are satisfactory. Trends and techniques in cord blood transplantation in this state are comparable with those observed nationally and overseas. Although numbers are small, cell dose appears to be predictive of overall survival

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.

Adults requiring cord blood transplants but have insufficient cell doses from a single cord blood unit can receive two units with successful engraftment kinetics similar to those of children receiving a single unit

We retrospectively evaluated neutrophil engraftment kinetics in 29 single versus nine double unit cord blood transplants (CBTs). All single CBTs were performed in pediatric patients (non-malignant/malignant diseases, 19/10), while all double CBTs were performed in adults (n = 8) and an adolescent (n = 1) with hematological malignancies. Median follow-up time was 2.3 years (range, 0.1-13.5 years). Engraftment was achieved in 69% and 89% of the single and double cord blood (CB) groups, respectively. Similarly, median day of engraftment was not different for the single versus the double CBTs, at 19 and 23 days, respectively, and the neutrophil engraftment kinetics was similar in the two groups. Our data indicate that adults without sufficient nucleated cell doses in a single CB unit may receive two units with similar engraftment kinetics to those of children receiving only a single unit.

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.

Overcoming the barriers to umbilical cord blood transplantation

Umbilical cord blood (UCB) transplantation (UCBT) has seen a marked increase in utilization in recent years, especially in the pediatric population; however, graft failure, delayed engraftment and profound delay in immune reconstitution leads to significant morbidity and mortality in adults. The lack of cells available for post-transplant therapies, such as donor lymphocyte infusions, has also been considered a disadvantage. To overcome the cell-dose barrier, the combination of two UCB units is becoming commonplace in adolescent and adult populations, and is currently being studied in pediatrics as well. In some studies, the use of two UCB units appears to have a positive impact on outcomes; however, engraftment is still suboptimal. A possible additional way to improve outcome and extend applicability of UCBT is via ex vivo expansion. Studies to develop optimal expansion conditions are still in the exploratory phase; however, recent studies suggest expanded UCB is safe and can improve outcomes. The ability to transplant across HLA disparities, rapid procurement time and decreased graft-versus-host disease (GvHD) seen with UCBT makes it a promising stem cell source and, while barriers exist, consistent progress is being made to overcome them.

Notch-mediated expansion of human cord blood progenitor cells capable of rapid myeloid reconstitution

Delayed myeloid engraftment after cord blood transplantation (CBT) is thought to result from inadequate numbers of progenitor cells in the graft and is associated with increased early transplant-related morbidity and mortality. New culture strategies that increase the number of cord blood progenitors capable of rapid myeloid engraftment after CBT would allow more widespread use of this stem cell source for transplantation. Here we report the development of a clinically relevant Notch-mediated ex vivo expansion system for human CD34(+) cord blood progenitors that results in a marked increase in the absolute number of stem/progenitor cells, including those capable of enhanced repopulation in the marrow of immunodeficient nonobese diabetic-severe combined immunodeficient (NOD-SCID) mice. Furthermore, when cord blood progenitors expanded ex vivo in the presence of Notch ligand were infused in a clinical setting after a myeloablative preparative regimen for stem cell transplantation, the time to neutrophil recovery was substantially shortened. To our knowledge, this is the first instance of rapid engraftment derived from ex vivo expanded stem/progenitor cells in humans.