Umbilical cord blood transplantation: basic biology and clinical challenges to immune reconstitution

CD22-targeted glyco-engineered natural killer cells offer a further treatment option for B-cell acute lymphoblastic leukemia

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Umbilical cord blood derived cell expansion: a potential neuroprotective therapy

Umbilical cord blood (UCB) is a rich source of beneficial stem and progenitor cells with known angiogenic, neuroregenerative and immune-modulatory properties. Preclinical studies have highlighted the benefit of UCB for a broad range of conditions including haematological conditions, metabolic disorders and neurological conditions, however clinical translation of UCB therapies is lacking. One barrier for clinical translation is inadequate cell numbers in some samples meaning that often a therapeutic dose cannot be achieved. This is particularly important when treating adults or when administering repeat doses of cells. To overcome this, UCB cell expansion is being explored to increase cell numbers. The current focus of UCB cell expansion is CD34+ haematopoietic stem cells (HSCs) for which the main application is treatment of haematological conditions. Currently there are 36 registered clinical trials that are examining the efficacy of expanded UCB cells with 31 of these being for haematological malignancies. Early data from these trials suggest that expanded UCB cells are a safe and feasible treatment option and show greater engraftment potential than unexpanded UCB. Outside of the haematology research space, expanded UCB has been trialled as a therapy in only two preclinical studies, one for spinal cord injury and one for hind limb ischemia. Proteomic analysis of expanded UCB cells in these studies showed that the cells were neuroprotective, anti-inflammatory and angiogenic. These findings are also supported by in vitro studies where expanded UCB CD34+ cells showed increased gene expression of neurotrophic and angiogenic factors compared to unexpanded CD34+ cells. Preclinical evidence demonstrates that unexpanded CD34+ cells are a promising therapy for neurological conditions where they have been shown to improve multiple indices of injury in rodent models of stroke, Parkinson's disease and neonatal hypoxic ischemic brain injury. This review will highlight the current application of expanded UCB derived HSCs in transplant medicine, and also explore the potential use of expanded HSCs as a therapy for neurological conditions. It is proposed that expanded UCB derived CD34+ cells are an appropriate cellular therapy for a range of neurological conditions in children and adults.

Haploidentical Cord Blood Transplantation with 8 mg/kg Antithymocyte Globulin as Graft-versus-Host Disease Prophylaxis Compared to Haploidentical Transplantation with 10 mg/kg Antithymocyte Globulin in the Treatment of Acute Leukemia

Clinical outcomes of the transplantation strategy combined with a haploidentical stem cell graft and an unrelated umbilical cord blood unit (haplo-cord HSCT) with low-dose antithymocyte globulin (ATG) as graft-versus-host disease (GVHD) prophylaxis for the treatment of acute leukemia remains unclear. This study aimed to explore the clinical outcomes of haplo-cord HSCT in acute leukemia patients with the GVHD prevention strategy of 8 mg/kg ATG compared with haploidentical transplantation with 10 mg/kg ATG. A total of 130 patients with acute leukemia who underwent allogeneic HSCT between January 2016 and December 2020 were included in this study, including 70 patients who received haploidentical stem cell grafts and unrelated umbilical cord blood units (haplo-cord HSCT) with 8 mg/kg ATG (haplo-cord-ATG8 group) and haploidentical HSCT with 10 mg/kg ATG (haplo-ATG10 group) in 60 patients. Clinical data were collected and analyzed retrospectively. Patients in the haplo-cord-ATG8 group were significantly older compared with the haplo-ATG10 group (P = .000). Haplo-cord HSCT with reduced ATG to 8 mg/kg results in more rapid neutrophil recovery (P = .036). No between-group differences were observed in platelet recovery or the incidences of Epstein-Barr virus viremia, bloodstream infection, or hemorrhagic cystitis. The rate of grade II-IV acute GVHD by day 100 post-transplantation was higher in the haplo-ATG10 group (27.16% versus 11.48%; P = .033), as was the rate of chronic GVHD at 1 year (14.60% versus 3.36%; P = .048). The rate of cytomegalovirus reaction was higher in the haplo-ATG10 group (48.31% versus 26.30%; P = .022). With a median follow-up of 27.4 months for the haplo-cord-ATG8 group and 27.5 months for the haplo-ATG10 group, overall survival (OS) at 2 years was 79.4% versus 62.8% (P = .005), event-free survival (EFS) was 76.3% versus 55.9% (P = .001), the cumulative incidence of relapse was 10.11% versus 25.97% (P = .164), and nonrelapse mortality (NRM) was 14.33% versus 24.43% (P = .0040). Multivariate analysis identified Center for International Blood and Marrow Transplant Research Disease Risk Index was the sole significant predictor of relapse, NRM, OS, and EFS. Haplo-cord HSCT supported by cord blood with 8 mg/kg ATG as GVHD prophylaxis results in better outcomes compared with haplo-HSCT with 10 mg/kg ATG.

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.

Fresh Umbilical Cord Blood-A Source of Multipotent Stem Cells, Collection, Banking, Cryopreservation, and Ethical Concerns

Umbilical cord blood (UCB) is a rich source of hematopoietic cells that can be used to replace bone marrow components. Many blood disorders and systemic illnesses are increasingly being treated with stem cells as regenerative medical therapy. Presently, collected blood has been stored in either public or private banks for allogenic or autologous transplantation. Using a specific keyword, we used the English language to search for relevant articles in SCOPUS and PubMed databases over time frame. According to our review, Asian countries are increasingly using UCB preservation for future use as regenerative medicine, and existing studies indicate that this trend will continue. This recent literature review explains the methodology of UCB collection, banking, and cryopreservation for future clinical use. Between 2010 and 2022, 10,054 UCB stem cell samples were effectively cryopreserved. Furthermore, we have discussed using Mesenchymal Stem Cells (MSCs) as transplant medicine, and its clinical applications. It is essential for healthcare personnel, particularly those working in labor rooms, to comprehend the protocols for collecting, transporting, and storing UCB. This review aims to provide a glimpse of the details about the UCB collection and banking processes, its benefits, and the use of UCB-derived stem cells in clinical practice, as well as the ethical concerns associated with UCB, all of which are important for healthcare professionals, particularly those working in maternity wards; namely, the obstetrician, neonatologist, and anyone involved in perinatal care. This article also highlights the practical and ethical concerns associated with private UCB banks, and the existence of public banks. UCB may continue to grow to assist healthcare teams worldwide in treating various metabolic, hematological, and immunodeficiency disorders.

Controversies and expectations for the prevention of GVHD: A biological and clinical perspective

Severe acute and chronic graft versus host disease (GVHD) remains a major cause of morbidity and mortality after allogeneic hematopoietic cell transplantation. Historically, cord blood and matched sibling transplantation has been associated with the lowest rates of GVHD. Newer methods have modified the lymphocyte components to minimize alloimmunity, including: anti-thymocyte globulin, post-transplant cyclophosphamide, alpha/beta T cell depletion, and abatacept. These agents have shown promise in reducing severe GVHD, however, can be associated with increased risks of relapse, graft failure, infections, and delayed immune reconstitution. Nonetheless, these GVHD prophylaxis strategies have permitted expansion of donor sources, especially critical for those of non-Caucasian decent who previously lacked transplant options. This review will focus on the biologic mechanisms driving GVHD, the method by which each agent impacts these activated pathways, and the clinical consequences of these modern prophylaxis approaches. In addition, emerging novel targeted strategies will be described. These GVHD prophylaxis approaches have revolutionized our ability to increase access to transplant and have provided important insights into the biology of GVHD and immune reconstitution.

Unrelated umbilical cord blood can improve the prognosis of haploidentical hematopoietic stem cell transplantation

Background

Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) is widely used as a curative treatment strategy for most types of hematological diseases. However, strategies for enhancing the graft versus leukemia (GVL) effect without aggravating the graft versus host disease (GVHD) effect are still being pursued.

Methods

A retrospective cohort study was performed to compare the outcomes between combined unrelated umbilical cord blood (UCB-haplo HSCT) and haplo HSCT.

Results

The results showed that neither acute GVHD (aGVHD) nor chronic GVHD (cGVHD) was increased in the UCB-haplo HSCT group, and the engraftment and infection rates were similar between the two groups. However, overall survival and progression-free survival were significantly improved, while transplantation-related mortality and relapse were significantly decreased in the UCB-haplo HSCT group by both univariate and multivariate analyses.

Conclusion

Our results indicated that the addition of a UCB unit could improve the prognosis of haplo-HSCT and enhance the GVL effect without increasing the incidence of GVHD.

Trial registration

The cohort study was retrospectively registered at https://www.chictr.org.cn as ChiCTR2100046681.

Human umbilical cord blood mononuclear cells transplantation for perinatal brain injury

Perinatal brain injury is a leading cause of death and disability in children. Hypoxic-ischemic encephalopathy in full term infants, and white matter injury in premature infants are most known brain injury in perinatal period. Human umbilical cord blood mononuclear cells contain hematopoietic stem cells, mesenchymal stem cells, endothelial progenitor cells, lymphocytes, monocytes, and so on. Human umbilical cord blood mononuclear cells have many biological functions, such as nerve and vascular regeneration, anti-apoptosis, anti-inflammation, and immune regulation. Human umbilical cord blood mononuclear cells transplantation has achieved significant efficacy and safety in animal and clinical trials for the treatment of perinatal brain injury. We will review human umbilical cord blood mononuclear cells transplantation for perinatal brain injury in this review.

Clinical Characteristics of Posttransplant Lymphoproliferative Disorder After Cord Blood Transplantation Without Antithymocyte Globulin

BACKGROUND

CBT with ATG use is a well-known PTLD risk factor. However, little is known regarding the clinical features of PTLD after ATG-free CBT.

PATIENTS AND METHODS

We analyzed the incidence, risk factors and prognosis of PTLD in 183 adults undergoing ATG-free CBT.

RESULTS

Fifteen patients (diffuse large B-cell lymphoma, n = 9, mucosa-associated lymphoid tissue lymphoma, n = 2 nondestructive PTLD, n = 1, T-cell lymphoma, n = 3) developed PTLD. The 2-year CuI of PTLD was 8.0% (95% CI: 4.6-12.7). Pathologically, all 12 B-cell PTLD patients had Epstein-Barr virus (EBV), compared with 1 of 3 T-cell PTLD patients. All patients, excluding one with nondestructive PTLD, showed extranodal involvement. In the univariate analysis, the 2-year CuI of PTLD was significantly higher in patients who received mycophenolate mofetil to prevent graft-versus-host disease than in nonrecipients (11.2%/2.9%, P = .0457). However, multivariate analysis revealed no independent PTLD risk factors. All 11 PTLD patients who received specific therapy achieved complete remission. The 1-year overall survival of PTLD patients was 70.9%.

CONCLUSION

Although we found a higher CuI of PTLD than previously reported, the prognosis was generally good. In CBT recipients, many factors, including MMF use, may be associated with the clinical features of PTLD.

Comparison of clinical outcomes between unrelated single umbilical cord blood and "ex-vivo" T-cell depleted haploidentical transplantation in children with hematological malignancies

BACKGROUND

Over the last two decades, umbilical cord blood (UCB) and haploidentical transplantation (HaploHSCT) have emerged as alternative sources of hematopoietic stem cell for allogeneic transplantation. There are few retrospective studies and no prospective studies comparing both types of alternative transplantation in pediatric patients.

RESULTS

We analyzed the data of 134 children with hematological malignancies who received a hematopoietic stem cell transplantation from a single umbilical cord blood (UCB) (n = 42) or an "ex-vivo" T-cell depleted transplant from a haploidentical-related donor (HaploHSCT) (n = 92) between 1996 and 2014. Hematological recovery was faster after HaploHSCT than the UCB transplant group (median times to neutrophil and platelet recovery: 13 vs. 16 days, 10 vs. 57 days, respectively) (P < 0.001). The HaploHSCT group had a significantly early immune reconstitution based on NK and CD8 + T cells compared with the UCB group. However, after the first year post-transplantation, HaploHSCT had a lower number of CD4 + T and B lymphocytes compared with the UCB transplant recipients. The cumulative incidence of TRM was 29±8% in the HaploHSCT group versus 40±5% in the UCB group. Relapse incidence was 21±7% in the HaploHSCT group and 19±8% in the UCB group. Probability of DFS was 58±8% in the HaploHSCT group versus 40±9% in the UCB group (P = 0.051).

CONCLUSIONS

TCD haploidentical transplant is associated with advantages in terms of engraftment and early immune reconstitution kinetics. TCD haploidentical transplant was associated with lower incidence of infectious and non-infectious complications, especially in the early phases of the transplant compared with UCB transplant recipients. However, there are no advantages in transplant outcomes compared with UCB transplant.

Umbilical cord blood transplantation: Still growing and improving

Umbilical cord blood transplantation (UCBT) has been performed in the clinic for over 30 years. The biological and immunological characteristics of umbilical cord blood (UCB) have been re-recognized in recent years. UCB, previously considered medical waste, is rich in hematopoietic stem cells (HSCs), which are naïve and more energetic and more easily expanded than other stem cells. UCB has been identified as a reliable source of HSCs for allogeneic hematopoietic stem cell transplantation (allo-HSCT). UCBT has several advantages over other methods, including no harm to mothers and donors, an off-the-shelf product for urgent use, less stringent HLA match, lower incidence and severity of chronic graft-vs-host disease (GVHD), and probably a stronger graft-vs-leukemia effect, especially for minimal residual disease-positive patients before transplant. Recent studies have shown that the outcome of UCBT has been improved and is comparable to other types of allo-HSCT. Currently, UCBT is widely used in malignant, nonmalignant, hematological, congenital and metabolic diseases. The number of UCB banks and transplantation procedures increased exponentially before 2013. However, the number of UCBTs increased steadily in Asia and China but decreased in the United States and Europe year-on-year from 2013 to 2019. In this review, we focus on the development of UCBT over the past 30 years, the challenges it faces and the strategies for future improvement, including increasing UCB numbers, cord blood unit selection, conditioning regimens and GVHD prophylaxis for UCBT, and management of complications of UCBT.

iNKT cells coordinate immune pathways to enable engraftment in nonconditioned hosts

Invariant natural killer T (iNKT) cells are a conserved population of innate T lymphocytes that interact with key antigen-presenting cells to modulate adaptive T-cell responses in ways that can either promote protective immunity, or limit pathological immune activation. Understanding the immunological networks engaged by iNKT cells to mediate these opposing functions is a key pre-requisite to effectively using iNKT cells for therapeutic applications. Using a human umbilical cord blood xenotransplantation model, we show here that co-transplanted allogeneic CD4+ iNKT cells interact with monocytes and T cells in the graft to coordinate pro-hematopoietic and immunoregulatory pathways. The nexus of iNKT cells, monocytes, and cord blood T cells led to the release of cytokines (IL-3, GM-CSF) that enhance hematopoietic stem and progenitor cell activity, and concurrently induced PGE2-mediated suppression of T-cell inflammatory responses that limit hematopoietic stem and progenitor cell engraftment. This resulted in successful long-term hematopoietic engraftment without pretransplant conditioning, including multi-lineage human chimerism and colonization of the spleen by antibody-producing human B cells. These results highlight the potential for using iNKT cellular immunotherapy to improve rates of hematopoietic engraftment independently of pretransplant conditioning.

Reduction of Graft-versus-Host-Disease in NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) Mice by Cotransplantation of Syngeneic Human Umbilical Cord-Derived Mesenchymal Stromal Cells

Graft-versus-host disease (GVHD) is one of the major complications following hematopoietic stem cell transplantation, which remains the sole curative therapy for many malignant diseases of the hematopoietic system. The immunomodulatory potential of mesenchymal stromal cells (MSCs) to treat GVHD is currently being tested in various preclinical and clinical trials. Because the results of the preclinical and clinical trials on the use of MSCs to treat GVHD have not been consistent, we analyzed the potential beneficial effects of syngeneic versus allogenic treatment, culture expansion of MSCs, and various MSC cell doses and time points of MSC transplantation in a murine GVHD model. We established the murine GVHD model based on the transplantation of umbilical cord blood-derived hematopoietic stem cells (UC-HSCs) and used this model to assess the therapeutic potential of umbilical cord blood-derived MSCs (UC-MSCs). The use of HSC and MSC populations derived from the same donor allowed us to exclude third-party cells and test the UC-HSCs and UC-MSCs in a matched setting. Moreover, we were able to compare various doses, transplantation time points, and the influence of culture expansion of MSCs on the impact of treatment. This resulted in 16 different treatment groups. The most efficient setting for treatment of UC-HSC-induced GVHD reactions was based on the simultaneous administration of 1 × 10⁶ culture-expanded, syngeneically matched UC-MSCs. This therapy effectively reduced the number of CD8⁺ T cells in the blood, protected the mice from weight loss, and prolonged their survival until the end of observation period. Taken together, our data show beneficial effects of (1) syngeneic over allogeneic UC-HSCs and UC-MSCs, (2) culture-expanded cells over freshly isolated primary cells, (3) simultaneous over sequential administration, and (4) high doses of UC-MSCs. The animal model of GVHD established here is now available for more detailed studies, including a comparative analysis of the efficacy of MSCs derived from alternative sources, such as adipose tissue and bone marrow.

Outcomes of Adolescents and Young Adults Compared with Children with Acute Leukemia after Single-Unit Unrelated Cord Blood Transplantation Using Myeloablative Conditioning without Antithymocyte Globulin

BACKGROUND

Although the use of cord blood transplantation (CBT) is becoming more frequent in acute leukemia, considering the relationship between the low stem cell dose and graft failure, whether use of CBT for adolescents and young adults (AYAs) is appropriate remains uncertain.

METHODS

A retrospective registry-based analysis of clinical outcomes and immune reconstitution was conducted for 105 AYAs and 187 children with acute leukemia who underwent single-unit CBT using myeloablative conditioning (MAC) without antithymocyte globulin (ATG).

RESULTS

Outcomes were similar between AYAs and children, except for nonrelapse mortality (NRM) and recovery rates of neutrophils and platelets. The 30-day cumulative incidence of neutrophil engraftment was similar between AYAs and children, but children had faster rates of neutrophil and platelet recovery than AYAs. The median time to neutrophil engraftment was earlier in children than in AYAs (AYAs, 19 days, 95% confidence interval [CI] 17.3-21.7; children, 16 days, 95% CI 13.1-19.5, p = 0.00003). The incidence of platelet recovery on day 120 was higher in children than in AYAs (AYAs, 80%, 95% CI 71-81%; children, 88%, 95% CI 82-92%, p = 0.037). CD34+ cell dose was the only independent factor influencing both neutrophil and platelet recovery. The cumulative incidence of NRM at 2 years was higher among AYAs than among children (AYAs, 27.5%, 95% CI 20-37%; children, 15%, 95% CI 10-21%, p = 0.008). Conditioning regimen was an independent factor influencing NRM. With respect to immune reconstitution, natural killer cell counts quickly recovered to normal levels 1-month post-CBT in both children and AYAs. CD8+ T-cell counts were higher in children than in AYAs at 1 and 3 months post-CBT. CD4+ T-cell counts were similar in both children and AYAs after CBT.

CONCLUSION

AYAs with acute leukemia have outcomes of single-unit CBT using MAC without ATG that are as good as those of children. Thus, single-unit CBT using modified MAC without ATG is an acceptable choice for both AYAs and children who do not have a suitable donor.

Umbilical cord blood transplantation can overcome the poor prognosis of KMT2A-MLLT3 acute myeloid leukemia and can lead to good GVHD-free/relapse-free survival

This is a retrospective study comparing the effectiveness of umbilical cord blood transplantation (UCBT) and chemotherapy for patients in the first complete remission period for acute myeloid leukemia with KMT2A-MLLT3 rearrangements. A total of 22 patients were included, all of whom achieved first complete remission (CR1) through 1–2 rounds of induction chemotherapy, excluding patients with an early relapse. Twelve patients were treated with UCBT, and 10 patients were treated with chemotherapy after 2 to 4 courses of consolidation therapy. The 3-year overall survival (OS) of the UCBT group was 71.3% (95% CI, 34.4–89.8%), and that of the chemotherapy group was 10% (95% CI, 5.89–37.3%). The OS of the UCBT group was significantly higher than that of the chemotherapy group (P = 0.003). The disease-free survival (DFS) of the UCBT group was 60.8% (95% CI, 25.0–83.6%), which was significantly higher than the 10% (95% CI, 5.72–35.8%) of the chemotherapy group (P = 0.003). The relapse rate of the UCBT group was 23.6% (95% CI, 0–46.8%), and that of the chemotherapy group was 85.4% (95% CI, 35.8–98.4%), which was significantly higher than that of the UCBT group (P < 0.001). The non-relapse mortality (NRM) rate in the UCBT group was 19.8% (95% CI, 0–41.3%), and that in the chemotherapy group was 0.0%. The NRM rate in the UCBT group was higher than that in the chemotherapy group, but there was no significant difference between the two groups (P = 0.272). Two patients in the UCBT group relapsed, two died of acute and chronic GVHD, and one patient developed chronic GVHD 140 days after UCBT and is still alive, so the GVHD-free/relapse-free survival (GRFS) was 50% (95% CI, 17.2–76.1%). AML patients with KMT2A-MLLT3 rearrangements who receive chemotherapy as their consolidation therapy after CR1 have a very poor prognosis. UCBT can overcome the poor prognosis and significantly improve survival, and the GRFS for these patients is very good. We suggest that UCBT is a better choice than chemotherapy for KMT2A-MLLT3 patients.

Impact of T Cell Repertoire Diversity on Mortality Following Cord Blood Transplantation

Introduction

Cord blood transplantation (CBT) recipients are at increased risk of mortality due to delayed immune recovery (IR). Prior studies in CBT patients have shown that recovery of absolute lymphocyte count is predictive of survival after transplant. However, there are no data on the association of T-cell receptor (TCR) and clinical outcomes after CBT. Here we retrospectively performed TCR beta chain sequencing on peripheral blood (PB) samples of 34 CBT patients.

Methods

All patients received a total body irradiation based conditioning regimen and cyclosporine and MMF were used for graft versus host disease (GvHD) prophylaxis. PB was collected pretransplant on days 28, 56, 80, 180, and 1-year posttransplant for retrospective analysis of IR utilizing high-throughput sequencing of TCRβ rearrangements from genomic DNA extracted from PB mononuclear cells. To test the association between TCR repertoire diversity and patient outcomes, we conducted a permutation test on median TCR repertoire diversity for patients who died within the first year posttransplant versus those who survived.

Results

Median age was 27 (range 1–58 years) and most of the patients (n = 27) had acute leukemias. There were 15 deaths occurring between 34 to 335 days after transplant. Seven deaths were due to relapse. Rapid turnover of T cell clones was observed at each time point, with TCR repertoires stabilizing by 1-year posttransplant. TCR diversity values at day 100 for patients who died between 100 and 365 days posttransplant were significantly lower than those of the surviving patients (p = 0.01).

Conclusions

Using a fast high-throughput TCR sequencing assay we have demonstrated that high TCR diversity is associated with better patient outcomes following CBT. Importantly, this assay is easily performed on posttransplant PB samples, even as early as day 28 posttransplant, making it an excellent candidate for early identification of patients at high risk of death.

Optimizing Preparative Regimen for Umbilical Cord Blood Transplantation in Adult Acute Leukemia Patients: Acute Lymphoblastic Leukemia Requires Myeloablative Conditioning but Not Acute Myeloid Leukemia

Cord blood transplantation (CBT) is a valuable alternative to bone marrow transplantation in adults without readily available donors. We conducted this study to investigate the feasibility of CBT for adult patients with acute leukemia with regards to impact of different conditioning and graft-versus-host disease (GVHD) prophylaxis regimens on clinical outcomes. From 16 centers in Korea, 41 acute myeloid leukemia (AML) and 29 ALL (acute lymphoblastic leukemia) patients undergoing CBT were enrolled. For AML patients, the neutrophil engraftment was observed in 87.5% of reduced intensity conditioning (RIC) and 72.0% of myeloablative conditioning (MAC) (p = 0.242). The median RFS was 5 months and OS 7 months. Conditioning regimen did not affect relapse free survival (RFS) or overall survival (OS). GVHD prophylaxis using calcineurin inhibitors (CNI) plus methotrexate was associated with better RFS compared to CNI plus ATG (p = 0.032). For ALL patients, neutrophil engraftment was observed in 55.6% of RIC and 90.0% of MAC (p = 0.034). The median RFS was 5 months and OS 19 months. MAC regimens, especially total body irradiation (TBI)-based regimen, were associated with both longer RFS and OS compared to other conditioning regimens. In conclusion, individualized conditioning regimens will add value in terms of enhancing safety and efficacy of CBT.

Letermovir Prophylaxis Decreases Burden of Cytomegalovirus (CMV) in Patients at High Risk for CMV Disease Following Hematopoietic Cell Transplant

Despite effective therapies, cytomegalovirus (CMV) continues to have a significant impact on morbidity and mortality in hematopoietic cell transplant recipients. At particular risk are recipients of alternative grafts such as umbilical cord blood (UCB), haploidentical transplants (haplo), or patients conditioned with T-cell depleting regimens such as anti-thymocyte globulin (ATG). With the approval of letermovir, its impact on high-risk patients is of particular interest. To evaluate the impact of letermovir prophylaxis at our center, we performed a retrospective analysis of 114 high-risk patients who received letermovir as prophylaxis (LET PPX) between January 2018 through December 2019, including 30 UCB and 22 haplo recipients, compared with 637 historical controls with comparable risk between January 2013 and December 2019. By post-transplant day 100 (D+100), letermovir prophylaxis significantly decreased the incidence of both CMV DNAemia compared with controls (45.37% versus 74.1%; P < .001) and clinically significant CMV infection (12.04% versus 48.82%; P < .001). The impact of LET PPX was even more profound on the incidence of clinically significant CMV infection (CSI), defined as the administration of antiviral therapy as preemptive therapy for CMV DNAemia or treatment for CMV disease. CSI was significantly lower in haplo recipients on LET PPX compared with controls (13.64% versus 73.33%; P= .02) and UCB recipients on LET PPX compared with controls (3.45% versus 37.5%; P < .001). No patients on LET primary PPX developed CMV disease in any treatment group by D+100 compared with controls (0% versus 5.34%, respectively; P = .006). Patients on LET PPX had fewer hospitalizations involving initiation of anti-CMV therapy compared with controls (0.93% versus 15.23%, respectively). Our analysis of the largest cohort of patients at high risk for CMV reactivation published to date demonstrates that letermovir prophylaxis significantly reduces the number of patients who receive CMV-active antiviral therapy for either DNAemia or disease due to CMV.

Safety and feasibility of virus-specific T cells derived from umbilical cord blood in cord blood transplant recipients

Adoptive transfer of virus-specific T cells (VSTs) has been shown to be safe and effective in stem cell transplant recipients. However, the lack of virus-experienced T cells in donor cord blood (CB) has prevented the development of ex vivo expanded donor-derived VSTs for recipients of this stem cell source. Here we evaluated the feasibility and safety of ex vivo expansion of CB T cells from the 20% fraction of the CB unit in pediatric patients receiving a single CB transplant (CBT). In 2 clinical trials conducted at 2 separate sites, we manufactured CB-derived multivirus-specific T cells (CB-VSTs) targeting Epstein-Barr virus (EBV), adenovirus, and cytomegalovirus (CMV) for 18 (86%) of 21 patients demonstrating feasibility. Manufacturing for 2 CB-VSTs failed to meet lot release because of insufficient cell recovery, and there was 1 sterility breach during separation of the frozen 20% fraction. Delayed engraftment was not observed in patients who received the remaining 80% fraction for the primary CBT. There was no grade 3 to 4 acute graft-versus-host disease (GVHD) associated with the infusion of CB-VSTs. None of the 7 patients who received CB-VSTs as prophylaxis developed end-organ disease from CMV, EBV, or adenovirus. In 7 patients receiving CB-VSTs for viral reactivation or infection, only 1 patient developed end-organ viral disease, which was in an immune privileged site (CMV retinitis) and occurred after steroid therapy for GVHD. Finally, we demonstrated the long-term persistence of adoptively transferred CB-VSTs using T-cell receptor-Vβ clonotype tracking, suggesting that CB-VSTs are a feasible addition to antiviral pharmacotherapy.

Rapid reconstitution of regulatory T-cell subsets is associated with reduced rates of acute graft-versus-host disease and absence of viremia after cord blood transplantation in children with reduced-intensity conditioning using alemtuzumab

Forkhead box P3 (FOXP3)+ regulatory T cell (Treg) reconstitution after unrelated donor umbilical cord blood transplantation in chemotherapy-naïve children is incompletely characterized. We studied 21 children with nonmalignant diseases receiving an identical alemtuzumab-containing regimen. We hypothesized that Treg recovery may be perturbed in patients not only by acute graft-versus-host disease (aGVHD) but also by viremia. Tregs and their memory and naïve subsets were serially monitored for proliferation and apoptosis along with conventional T cells (Tcon). A "reconstitution index" (RI) was calculated relative to pretransplantation values for each parameter. At 3 months post-UCBT, the RI of Tregs was faster compared with other immune components tested and was most rapid in patients free of aGVHD and viremia. There were significantly fewer Tregs in patients experiencing grade I-II aGVHD and/or viremia, leading to an imbalance between Tregs-Tcon ratios. Central and effector memory Tregs were most affected at this time point when they dominated in the circulation. Impaired Treg proliferation without increased apoptosis accounted for the reduced Treg-Tcon ratio. In patients affected with grade II aGVHD and viremia, the overall reduction in circulating Treg pool were associated with a more oligoclonal T-cell receptor β repertoire. Taken together, aGVHD and viremia can lead to defective Treg expansion homeostasis.

Letermovir prophylaxis through day 100 post transplant is safe and effective compared with alternative CMV prophylaxis strategies following adult cord blood and haploidentical cord blood transplantation

We compared CMV outcomes of three prophylactic approaches used for CBT and haploidentical cord transplants from December 2009 through 2018: letermovir (n = 32) through day 100 post transplant, "valacyclovir day 100" (valacyclovir 2 g orally three times daily through day 100) (n = 60), and "valacyclovir hospital discharge" (valacyclovir 2 g orally three times daily through hospital discharge then acyclovir 800 mg twice daily) (n = 41). Through day 100, none in the letermovir group, six (10%) in the "valacyclovir day 100," and nine (22%) in the "valacyclovir hospital discharge" group required CMV directed treatment (p = 0.005 and 0.06 comparing letermovir to "valacyclovir hospital discharge" and "valacyclovir day 100"). Fewer patients in the letermovir group (n = 7, 22%) had any CMV reactivation versus the "valacyclovir day 100" group (n = 20, 33%) versus the "valacyclovir hospital discharge" group (n = 23, 57%) (p = 0.003 and 0.21 comparing letermovir to "valacyclovir hospital discharge" and "valacyclovir day 100"). Among patients not reactivating CMV before 100 days, reactivation rates between day 100 and 180 were higher in the letermovir and "valacyclovir day 100" groups than the "valacyclovir hospital discharge" group. Letermovir is safe and effective compared with alternative prophylaxis approaches following CBT through day 100. Reactivation and monitoring after day 100 remain potential concerns.

Successful Salvage Haploidentical Alpha-Beta T Cell-Depleted Stem Cell Transplantation After Busulfan-Based Myeloablation in a Patient With IPEX Syndrome: A Case Report

BACKGROUND

X-linked immunodysregulation syndrome with polyendocrinopathy and enteropathy (IPEX) is caused by FOXP3 gene mutations that block the generation of regulatory T lymphocytes. We report an 18-month-old boy with classic IPEX who underwent 2 hematopoietic stem cell transplantations (HSCTs).

METHODS

The first HSCT from an unrelated 8/10 HLA-matched umbilical cord blood donor (UCB) was performed after a conditioning regimen consisting of treosulfan, fludarabine, thiotepa, and thymoglobulin. Due to complete rejection of the UCB transplant, a second transplantation from a 6/10 HLA-matched mother was performed after alpha-beta T-cell depletion. The second conditioning regimen consisted of busulfan, fludarabine, a single dose of cyclophosphamide 1 g/m², and Grafalon (Neovii Pharmaceuticals, Rapperswil, Switzerland). The T-cell depletion product contained 15.06 x 10⁶ CD34+ cells per kilogram body weight (BW) and 4.19 x 10⁵ alpha-beta T lymphocytes per kilogram BW. Due to acute graft rejection, the boy was treated with thymoglobulin, and full donor chimerism in both T lymphocytes and mononuclear cells was achieved. The immunosuppressive therapy was stopped 1 year after transplantation. To date, the patient remains free from graft-vs-host disease (GVHD) and immunosuppression.

CONCLUSIONS

HSCT after busulfan-based reduced-toxicity conditioning in patients with IPEX syndrome is feasible and well tolerated and can result in full donor engraftment. Monitoring of chimerism and aggressive therapy in cases of graft rejection are warranted due to the high reactivity of residual autologous T lymphocytes. T-cell depletion reduces the risk of GVHD and the need for steroid therapy, which is especially challenging in patients with diabetes.

A Glycomic Approach Towards Identification of Signature Molecules in CD34+ Haematopoietic Stem Cells from Umbilical Cord Blood

Umbilical cord blood (UCB) is a powerful storehouse for normal CD34⁺ haematopoietic stem cells (HSCs), often used for allogeneic bone marrow (BM) transplantation in malignant and non-malignant diseases. The glycomic especially the sialoglycomic aspect of these HSCs has been unravelled in this study. Cell surface expression of the glycans with the related enzymatic activities has been compared with the BM of childhood acute lymphoblastic leukaemia, a common BM-associated malignancy. An enhanced cell surface expression of α2,3-linked sialic acid, P- and E-selectins, and intercellular adhesion molecule along with reduced expression of L-selectin distinguishes CD34⁺ HSCs of UCB from leukaemic samples. More importantly, high expression of O-acetylated sialoglycoproteins, a hallmark of lymphoblasts, is drastically reduced in the CD34⁺ HSCs of UCB and is substantiated by the low activity of sialylate-O-acetyltransferase and high sialidase activity. In contrast, a significant variation is evident in the expression of sialic acid, α2,6-linked sialic acids, and the sialyltransferase activity. Taken together, these studies indicate a few signature molecules, forming a unique glycomic template, which may be a potential indicator, reassuring the normal profile of these stem cells, to be used for future transplantation.

Reactivation of BK virus after double umbilical cord blood transplantation in adults correlates with impaired reconstitution of CD4+ and CD8+ T effector memory cells and increase of T regulatory cells

BK virus (BKV), a human polyomavirus that remains latent in renal epithelial cells, can be reactivated after hematopoietic stem cell transplantation (HSCT) leading to hemorrhagic cystitis. The incidence of BK viremia is higher after Umbilical cord blood transplantation (UCBT) than HSCT from adult donors. Data regarding the role of immune recovery after UCBT in BKV reactivation is lacking. We examined the correlation between the development of BK viremia and immune reconstitution in 27 adult recipients of UCBT. The incidence of BK viremia was 52% and developed most frequently within the first 8 weeks after the transplantation, but persisted in seven patients at 6 months, and three patients at 1-year post UCBT. Detection of BK viremia 1 year after transplant was negatively associated with the number of CD8⁺ cells (p = 0.03) and CD8⁺CD45RO⁺ cells (p = 0.05) at 6 months, and the number of CD4⁺ (p = 0.03) and CD4⁺CD45RO⁺ cells (p = 0.03) at 12 months after UCBT. Conversely, BK viremia at 6 and 12 months was positively correlated with the number of T regulatory (Treg) cells at 1 month (p = 0.005 and p = 0.016, respectively). Because UCB Treg have highly potent immunosuppressive function, our findings indicate that sustained BK viremia in UCBT recipients might be associated with the increase of Treg cells early after transplantation, which mediate impaired and delayed reconstitution of CD4⁺ and CD8⁺ T effector cells.

Impact of immunoglobulin G2 subclass level on late-onset bacterial infection after allogeneic hematopoietic stem cell transplantation

BACKGROUND

Immunoglobulin (Ig) G2 subclass deficiency is known to be associated with recurrent bacterial respiratory infections caused by capsulated bacteria and is found mostly in pediatric patients. However, its impact after allogeneic hematopoietic stem cell transplantation (HSCT) has not been fully assessed.

METHODS

We retrospectively evaluated the relationship between IgG2 subclass levels and bacterial pneumonia in 74 adult patients who survived longer than 2 years after allogeneic HSCT.

RESULTS

During the evaluation period, nine patients developed bacterial pneumonia. The median IgG2 level was significantly lower in patients with an infectious episode than in those without (143 mg/dL vs 287 mg/dL; P < 0.01). In multivariate analysis, a history of rituximab therapy and cord blood as a stem cell source were significantly associated with decreased levels of both IgG2 and IgG2/IgG ratios (P < 0.05).

CONCLUSIONS

Suboptimal serum IgG2 levels could increase susceptibility to late-onset bacterial pneumonia after allogeneic HSCT. IgG2 levels should be considered carefully, especially in patients receiving cord blood transplantation and/or rituximab treatment.

Comparison of Graft Acquisition and Early Direct Charges of Haploidentical Related Donor Transplantation versus Umbilical Cord Blood Transplantation

Alternative donor allogeneic hematopoietic cell transplants (HCTs), such as double umbilical cord blood transplants (dUCBT) and haploidentical related donor transplants (haplo-HCT), have been shown to be safe and effective in adult patients who do not have an HLA-identical sibling or unrelated donor available. Most transplant centers have committed to 1 of the 2 alternative donor sources, even with a lack of published randomized data directly comparing outcomes and comparative data on the cost-effectiveness of dUCBT versus haplo-HCT. We conducted a retrospective study to evaluate and compare the early costs and charges of haplo-HCT and dUCBT in the first 100 days at 2 US transplant centers. Forty-nine recipients of haplo-HCT (at 1 center) and 37 with dUCBT (at another center) were included in the analysis. We compared graft acquisition, inpatient/outpatient, and total charges in the first 100 days. The results of the analysis showed a significantly lower cost of graft acquisition and lower total charges (for 100-day HCT survivors) in favor of haplo-HCT. Importantly, to control for the obvious shortcomings of comparing costs at 2 different transplant centers, adjustments were made based on the current (2018) local wage index and inflation rate. In the absence of further guidance from a prospective study, the cost analysis in this study suggests that haplo-HCT may result in early cost savings over dUCBT and may be preferred by transplant centers and for patients with more limited resources.

Clinical outcomes of unrelated cord blood transplantation in children with malignant and non-malignant diseases: Multicenter experience in China

This multicenter retrospective study included 184 children with malignant and non-malignant diseases who underwent UCBT between January 1998 and August 2012. The malignant disease group included 101 children with ALL, AML, CML, JMML, and MDS, and the non-malignant disease group included 83 children with PID, β-thalassemia, IMD BMF, and HLH. The median duration to neutrophil and platelet engraftment was 16 and 35 days in the malignant disease group vs 15 and 38 days in the non-malignant disease group. The cumulative incidence of grade II-IV aGVHD and cGVHD was 25.6% and 13.5% in the malignant disease group vs 19.7% and 11.1% in the non-malignant disease group, respectively. The median duration and cumulative incidence of neutrophil and platelet engraftment, and the cumulative incidence of grade II-IV aGVHD and cGVHD were similar between the two groups. Of the 184 pediatric patients, 114 patients survived during a median follow-up period of 14 months (range 4-138). The 5-year OS and DFS were not statistically different between the two groups (56.3% and 46.1% in malignant disease group vs 68.5% and 52.8% in non-malignant disease group). The above results indicate that UCB is a viable source for HSCT for children with malignant or non-malignant diseases, especially in urgent cases.

Hyperbaric oxygen treatment effects on in vitro cultured umbilical cord blood CD34+ cells

BACKGROUND AIMS

Umbilical cord blood (UCB) provides an alternative source for hematopoietic stem/progenitor cells (HSPCs) in the treatment of hematological malignancies. However, clinical usage is limited due to the low quantity of HSPCs in each unit of cord blood and defects in bone marrow homing. Hyperbaric oxygen (HBO) is among the more recently explored methods used to improve UCB homing and engraftment. HBO works by lowering the host erythropoietin before UCB infusion to facilitate UCB HSPC homing, because such UCB cells are not directly exposed to HBO. In this study, we examined how direct treatment of UCB-CD34⁺ cells with HBO influences their differentiation, proliferation and in vitro transmigration.

METHODS

Using a locally designed HBO chamber, freshly enriched UCB-CD34⁺ cells were exposed to 100% oxygen at 2.5 atmospheres absolute pressure for 2 h before evaluation of proliferative capacity, migration toward a stromal cell-derived factor 1 gradient and lineage differentiation.

RESULTS

Our results showed that HBO treatment diminishes proliferation and in vitro transmigration of UCB-CD34⁺ cells. Treatment was also shown to limit the ultimate differentiation of these cells toward an erythrocyte lineage. As a potential mechanism for these findings, we also investigated HBO effects on the relative concentration of cytoplasmic and nucleic reactive oxygen species (ROS) and on erythropoietin receptor (Epo-R) and CXCR4 expression. HBO-treated cells showed a relative increase in nucleic ROS but no detectable differences in the level of Epo-R nor CXCR4 expression were established compared with non-treated cells.

DISCUSSION

In summary, HBO amplifies the formation of ROS in DNA of UCB-CD34⁺ cells, potentially explaining their reduced proliferation, migration and erythrocytic differentiation.

The role of policies and networks in development of cord blood usage in China

Research regarding the use of cord blood (CB) has focused on antigen match and the number of stem cells, with policies and networks related to its use being under researched. This article is based on fieldwork in China from 2013 to 2015 and examines ways that the studied CB bank enhances CB usage in China. This article identifies that in addition to finding a match, CB use is linked to the policies and networks, release fee and public awareness that enable CB usage development.

Adoptive T Cell Immunotherapy for Patients with Primary Immunodeficiency Disorders

Primary immunodeficiency disorders (PID) are a group of inborn errors of immunity with a broad range of clinical severity but often associated with recurrent and serious infections. While hematopoietic stem cell transplantation (HSCT) can be curative for some forms of PID, chronic and/or refractory viral infections remain a cause of morbidity and mortality both before and after HSCT. Although antiviral pharmacologic agents exist for many viral pathogens, these are associated with significant costs and toxicities and may not be effective for increasingly drug-resistant pathogens. Thus, the emergence of adoptive immunotherapy with virus-specific T lymphocytes (VSTs) is an attractive option for addressing the underlying impaired T cell immunity in many PID patients. VSTs have been utilized for PID patients following HSCT in many prior phase I trials, and may potentially be beneficial before HSCT in patients with chronic viral infections. We review the various methods of generating VSTs, clinical experience using VSTs for PID patients, and current limitations as well as potential ways to broaden the clinical applicability of adoptive immunotherapy for PID patients.

HLA-DPB1 mismatch induces a graft-versus-leukemia effect without severe acute GVHD after single-unit umbilical cord blood transplantation

Although it is known that human leukocyte antigen (HLA)-DPB1 disparity has a strong impact on outcomes in unrelated hematopoietic transplantation with induction of acute graft-versus-host disease (GVHD) and a graft-versus-leukemia (GVL) effect, its role in unrelated umbilical cord blood transplantation (UR-CBT) has yet to be fully clarified. Our current study is being conducted to elucidate the impact of HLA-DPB1 mismatch, along with the effect of other HLA loci mismatches at the allele level. HLA six loci alleles were retrospectively typed in 1157 Japanese donors and patients with leukemia or myelodysplastic syndrome who underwent transplantation with a single unit of cord blood. HLA-DPB1 mismatch was associated with a significant reduction in leukemia relapse (hazard ratio 0.61, P<0.001), whereas the other HLA loci allele-level mismatches did not. No significant effect of HLA-DPB1 mismatch was observed in the risk of acute GVHD, engraftment or mortality. This HLA-DPB1 GVL effect without induction of severe acute GVHD or deterioration of survival rate has not been reported in unrelated bone marrow or peripheral blood stem cell transplantations, suggesting apparent advantages of UR-CBT. Accordingly, selection of an HLA-DPB1 mismatch cord blood might be the preferable choice for single-unit UR-CBT.

Pericardial Effusion Following Hematopoietic Cell Transplantation in Children and Young Adults Is Associated with Increased Risk of Mortality

Hematopoietic cell transplantation (HCT) is curative for many pediatric malignant and nonmalignant disorders but is associated with significant morbidity and mortality, including the development of pericardial effusion (PEF). We report the results of a retrospective chart review performed to assess the incidence, risk factors, and prognostic significance of PEF in pediatric HCT recipient at Lucile Packard Children's Hospital of Stanford University. A total of 119 patients undergoing HCT between January 2010 and December 2013 were selected through the hospital's Pediatric Stem Cell Transplant Program database. A retrospective chart review, including review of documentation, correspondence, imaging reports, laboratory values, and death records, was performed to collect data. The overall incidence of PEF in our population was 21%. Risk factors for the development of PEF included unrelated donor transplants and cord blood as the stem cell source (P = .005), whereas HLA mismatch approached significance (P = .05). The risk for development of PEF was found to not be significantly associated with acute or chronic graft-versus-host disease (GVHD), age at transplantation, sex, conditioning regimen, or viral reactivation status. Of interest, 6 of the 119 patients were found to have transplant-associated thrombotic microangiopathy (TA-TMA). Four of those 6 patients developed PEF, suggesting TA-TMA as a risk factor for PEF. Eight of the 25 patients who developed PEF (32%) required pericardiocentesis. Five out of the 8 patients requiring pericardiocentesis died owing to causes unrelated to the procedure or to PEF itself. Pericardial fluid testing in 4 of these patients (50%) was positive for human herpesvirus 6, Epstein-Barr virus, cytomegalovirus, and/or adenovirus. Finally, of significant interest, patients with PEF had a statistically significant higher likelihood of mortality compared with those without PEF (44% versus 17%; P = .007).

Quantification of Active and Latent Form of Human Cytomegalovirus Infection in Umbilical Cord Blood Donors by Real-Time PCR

BACKGROUND

Umbilical cord blood (UCB) is believed to be a highly valuable source of hematopoietic stem cells for transplantation. Objective: To investigate the prevalence of active and latent human cytomegalovirus (CMV) infection in UCB donors in Iranian population.

METHODS

A total of 825 UCB samples was collected under standard procedures and analyzed for the presence of CMV DNAs in buffy coat (latent infection) and plasma (active infection). DNA was extracted from buffy coat and plasma samples separately and tested with quantitative real-time PCR. All positive samples were checked by ELISA for IgG and IgM anti-CMV antibody.

RESULTS

Latent CMV infection was detected in 17 (2%) buffy coat samples with a low level of viral load, which indicated the presence of latent viral infection in donors. None of the plasma samples were found positive for CMV DNA reflecting no active infection. In the 17 positive samples, CMV viral load was 91-104 (mean: 100) copies/mL. All samples positive for viral DNA were also found positive for CMV IgG antibody by ELISA. No CMV IgM antibody was detected in positive samples.

CONCLUSION

CMV is still the most important virus that infects hematopoietic stem cells and could be dangerous, especially for immunocompromized transplant recipients. We therefore suggest using real-time PCR for the detection and quantification of the viral DNA in buffy coat and plasma of UCB donors. PCR of plasma for detection of CMV and antibody assay for CMV infection add no more sensitivity for the detection of latent CMV infection in UCB donors.

Early and Long-Term Impaired T Lymphocyte Immune Reconstitution after Cord Blood Transplantation with Antithymocyte Globulin

Immune reconstitution is crucial to the success of allogeneic hematopoietic stem cell transplantation. Umbilical cord blood transplantation (UCBT) has been associated with delayed immune reconstitution. We characterized the kinetics and investigated the risk variables affecting recovery of the main lymphocyte subsets in 225 consecutive pediatric and adult patients (males, n = 126; median age, 15; range, .3 to 60; interquartile range, 4 to 35) who underwent myeloablative single UCBT between 2005 and 2015 for malignant and nonmalignant disorders. Low CD4⁺ and CD8⁺ T cell counts were observed up to 12 months after UCBT. In contrast, B and natural killer cells recovered rapidly early after transplantation. In a multivariate regression model, factors favoring CD4⁺ T cell recovery ≥ 200 cells/µL were lower dose antithymocyte globulin (ATG) (hazard ratio [HR], 3.93; 95% confidence interval [CI], 2.3 to 5.83; P = .001), negative recipient cytomegalovirus (CMV) serostatus (HR, 3.76; 95% CI, 1.9 to 5.74; P = .001), and younger age (HR, 2.61; 95% CI, 1.01 to 3.47; P = .03). Factors favoring CD8⁺ T cell recovery ≥ 200 cells/µL were lower dose ATG (HR, 3.03; 95% CI, 1.4 to 5.1; P = .03) and negative recipient CMV serostatus (HR, 1.9; 95% CI, 1.63 to 2.15; P = .01). Our results demonstrate the significant negative impact of ATG on lymphocyte recovery. A reduction of the dose or omission of ATG could improve immune reconstitution and perhaps reduce opportunistic infections after UCBT.

Clinical-scale expansion of CD34+ cord blood cells amplifies committed progenitors and rapid scid repopulation cells

Umbilical cord blood (UCB) transplantation is associated with long periods of aplastic anaemia. This undesirable situation is due to the low cell dose available per unit of UCB and the immaturity of its progenitors. To overcome this, we present a cell culture strategy aimed at the expansion of the CD34⁺ population and the generation of granulocyte lineage-committed progenitors. Two culture products were produced after either 6 or 14days of in vitro expansion, and their characteristics compared to non-expanded UCB CD34⁺ controls in terms of phenotype, colony-forming activity and multilineage repopulation potential in NOD-scid IL2Rγ^null mice. Both expanded cell products maintained rapid SCID repopulation activity similar to the non-expanded control, but 14-day cultured cells showed impaired long term SCID repopulation activity. The process was successfully scaled up to clinically relevant doses of 89×10⁶ CD34⁺ cells committed to the granulocytic lineage and 3.9×10⁹ neutrophil precursors in different maturation stages. Cell yields and biological properties presented by the cell product obtained after 14days in culture were superior and therefore this is proposed as the preferred production setup in a new type of dual transplant strategy to reduce aplastic periods, producing a transient repopulation before the definitive engraftment of the non-cultured UCB unit. Importantly, human telomerase reverse transcriptase activity was undetectable, c-myc expression levels were low and no genetic abnormalities were found, as determined by G-banding karyotype, further confirming the safety of the expanded product.

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.

Higher Early Monocyte and Total Lymphocyte Counts Are Associated with Better Overall Survival after Standard Total Body Irradiation, Cyclophosphamide, and Fludarabine Reduced-Intensity Conditioning Double Umbilical Cord Blood Allogeneic Stem Cell Transplantation in Adults

This single-center retrospective study aimed to report the impact of early hematopoietic and immune recoveries after a standard total body irradiation, cyclophosphamide, and fludarabine (TCF) reduced-intensity conditioning (RIC) regimen for double umbilical cord blood (dUCB) allogeneic stem cell transplantation (allo-SCT) in adults. We analyzed 47 consecutive patients older than 17 years who engrafted after a dUCB TCF allo-SCT performed between January 2006 and April 2013 in our department. Median times for neutrophil and platelet recoveries were 17 (range, 6 to 59) and 37 days (range, 0 to 164), respectively. The 3-year overall (OS) and disease-free survivals, relapse incidence, and nonrelapse mortality were 65.7%, 57.2%, 27.1%, and 19%, respectively. In multivariate analysis, higher day +30 monocyte (≥615/mm(3); hazard ratio [HR], .04; 95% confidence interval [CI], .004 to .36; P < .01) and day +42 lymphocyte (≥395/mm(3); HR, .16; 95% CI, .03 to .78; P = .02) counts were independently associated with better OS. These results suggest that early higher hematopoietic and immune recovery is predictive of survival after dUCB TCF RIC allo-SCT in adults. Factors other than granulocyte colony-stimulating factor, which was used in all cases, favoring expansion of monocytes or lymphocytes, should be tested in the future as part of the UCB transplantation procedure.

Immune reconstitution after cord blood transplantation: peculiarities, clinical implications and management strategies

Umbilical cord blood (UCB) is now widely used as an alternative hematopoietic stem cell source for patients lacking closely matched related or unrelated adult donors. UCB transplantation has traditionally been associated with delayed engraftment, poor immune reconstitution and consequent increased risk of infection. More recent clinical studies, however, suggest that conditioning regimens and in particular the omission of in vivo T-cell depletion may play a crucial role in post-transplant T-cell expansion, facilitating a uniquely rapid immune recovery after UCB transplantation. The peculiar characteristics of UCB cells, the importance of thymic function and the role of conditioning regimens and graft-versus-host disease influencing immune reconstitution are described. The last part of the review reports available data on UCB, as well as third-party peripheral blood derived anti-viral cell therapy, which provides a novel approach to rescue UCB recipients with viral complications in the post-transplant period.

Supportive care in alternative donor transplantation

Alternative donor hematopoietic cell transplantation (HCT) using umbilical cord blood, haploidentical or mismatched unrelated donors is a viable option for patients without human leukocyte antigen (HLA)-identical sibling or matched unrelated donors. The same principles of supportive care as conventional graft sources apply to alternative donor HCT recipients. However, there are some unique supportive care issues related to post-transplant complications, engraftment, graft-versus-host disease, immune reconstitution, and infections that are unique to each of the three alternative graft sources, both in the early and late post-transplant periods. This review discusses the supportive care issues relevant to this population and their management.

Same sibling marrow following cord allogeneic transplantation as therapy for second relapse acute promyelocytic leukemia in a pediatric patient

Optimal therapy for relapsed APL in pediatric patients is controversial. Allogeneic HSCT is an alternative, with event-free survival of 70-75%. We report a pediatric patient with APL who relapsed 28 months after CBT from her sibling and then was treated with BMT from the same donor. Bone marrow was selected for higher cell dose, donor availability, and partial donor chimerism. Persistent molecular remission was achieved, currently at 65 months after BMT. This case suggests the potential role of GVL activity in APL and illustrates the use of different cell sources from the same donor in allogeneic transplantation for pediatric patients.

Cord blood transplant for acute myeloid leukaemia

Umbilical cord blood is a haematopoietic progenitor cell source for patients with acute myeloid leukaemia (AML), other haematological malignancies and metabolic diseases who can be cured by allogeneic haematopoietic cell transplantation, but who do not have a human leucocyte antigen compatible related or unrelated donor. Although the first cord blood transplants were done in children, there are currently more cord blood transplants performed in adults. In this review, we explore the history of umbilical cord blood transplantation, paediatric and adult outcome results, and novel trends to improve engraftment and reduce infection. Umbilical cord blood transplantation cures approximately 30-40% of adults and 60-70% of children with AML. Controversial issues, including the use of double versus single cord blood units for transplantation, optimal cord blood unit selection, infection prophylaxis, conditioning regimens and graft versus host disease prophylaxis, will be reviewed. Finally, comparison to other graft sources, cost, access to care, and the ideal graft source are discussed.

Severe infections after single umbilical cord blood transplantation in adults with or without the co-infusion of CD34+ cells from a third-party donor: results of a multicenter study from the Grupo Español de Trasplante Hematopoyético (GETH)

BACKGROUND

Umbilical cord blood transplantation (CBT) is an established alternative source of stem cells in the setting of unrelated transplantation. When compared with other sources, single-unit CBT (sCBT) is associated with a delayed hematologic recovery, which may lead to a higher infection-related mortality (IRM). Co-infusion with the sCBT of CD34+ peripheral blood stem cells from a third-party donor (TPD) (sCBT + TPDCD34+) has been shown to markedly accelerate leukocyte recovery, potentially reducing the IRM. However, to our knowledge, no comparative studies have focused on severe infections and IRM with these 2 sCBT strategies.

METHODS

A total of 148 consecutive sCBT (2000-2010, median follow-up 4.5 years) were included in a multicenter retrospective study to analyze the incidence and risk factors of IRM and severe viral and invasive fungal infections (IFIs). Neutrophil engraftment occurred in 90% of sCBT (n = 77) and 94% sCBT + TPDCD34+ (n = 71) recipients at a median of 23 and 12 days post transplantation, respectively (P < 0.01).

RESULTS

The 4-year IRM was 24% and 20%, respectively (P = 0.7), with no differences at day +30 (5% and 4%, respectively) and day +100 (10% and 8%, respectively). In multivariate analysis early status of the underlying malignancy, cytomegalovirus (CMV)-seronegative recipient and high CD34+ cell content in the cord blood unit before cryostorage (≥1.4 × 10(5) /kg) were protective of IRM. Among the causes of IRM, bacterial infections and IFIs were more common in sCBT (15% vs. 4%), while CMV disease and parasitic infections were more common in the sCBT + TPDCD34+ cohort (5% vs. 16%).

CONCLUSION

These data show that sCBT supported with TPDCD34(+) cells results in much shorter periods of post-transplant leukopenia, but the short- and long-term rates of IRM were comparable to those of sCBT, presumably because immune recovery is equally delayed in both graft types.

Modulatory effects of mesenchymal stem cells on leucocytes and leukemic cells: A double-edged sword?

Mesenchymal stem cells (MSCs) have drawn much attention amongst stem cell researchers in the past few decades. The ability of the MSC to differentiate into cells of mesodermal and non-mesodermal origins has made them an attractive approach for cell-based therapy and regenerative medicine. The MSCs have immunosuppressive activities that may have considerable therapeutic values in autoimmune diseases. However, despite the many beneficial effects reported, there is a growing body of evidence, which suggests that MSCs could be a culprit of enhanced tumour growth, metastasis and drug resistance in leukaemia, via some modulatory effects. Many controversies regarding the interactions between MSCs and leukaemia still exist. Furthermore, the role of MSCs in leukemogenesis and its progression remain largely unknown. Hence it is important to understand how the MSCs modulate leukaemia before these cells could be safely used in the treatment of leukaemia patients.

Expansion of regulatory T cells from umbilical cord blood and adult peripheral blood CD4(+)CD25 (+) T cells

CD4(+)CD25(+) regulatory T cells (Treg), if properly expanded from umbilical cord blood (UCB), may provide a promising immunotherapeutic tool. Our previous data demonstrated that UCB CD4(+)CD25(+) T cells with 4-day stimulation have comparable phenotypes and suppressive function to that of adult peripheral blood (APB) CD4(+)CD25(+) T cells. We further examined whether 2-week culture would achieve higher expansion levels of Tregs. UCB CD4(+)CD25(+) T cells and their APB counterparts were stimulated with anti-CD3/anti-CD28 in the presence of IL-2 or IL-15 for 2 weeks. The cell proliferation and forkhead box P3 (FoxP3) expression were examined. The function of the expanded cells was then investigated by suppressive assay. IL-21 was applied to study whether it counteracts the function of UCB and APB CD4(+)CD25(+) T cells. The results indicate that UCB CD4(+)CD25(+) T cells expanded much better than their APB counterparts. IL-2 was superior to expand UCB and APB Tregs for 2 weeks than IL-15. FoxP3 expression which peaked on Day 10-14 was comparable. Most importantly, expanded UCB Tregs showed greater suppressive function in allogeneic mixed lymphocyte reaction. The addition of IL-21, however, counteracted the suppressive function of expanded UCB and APB Tregs. The results support using UCB as a source of Treg cells.

MicroRNAs and Metabolites in Serum Change after Chemotherapy: Impact on Hematopoietic Stem and Progenitor Cells

Hematopoietic regeneration after high dose chemotherapy necessitates activation of the stem cell pool. There is evidence that serum taken after chemotherapy comprises factors stimulating proliferation and self-renewal of CD34⁺ hematopoietic stem and progenitor cells (HSPCs) – however, the nature of these feedback signals is yet unclear. Here, we addressed the question if specific microRNAs (miRNAs) or metabolites are affected after high dose chemotherapy. Serum taken from the same patients before and after chemotherapy was supplemented for in vitro cultivation of HSPCs. Serum taken after chemotherapy significantly enhanced HSPC proliferation, better maintained a CD34⁺ immunophenotype, and stimulated colony forming units. Microarray analysis revealed that 23 miRNAs changed in serum after chemotherapy – particularly, miRNA-320c and miRNA-1275 were down-regulated whereas miRNA-3663-3p was up-regulated. miRNA-320c was exemplarily inhibited by an antagomiR, which seemed to increase proliferation. Metabolomic profiling demonstrated that 44 metabolites were less abundant, whereas three (including 2-hydroxybutyrate and taurocholenate sulphate) increased in serum upon chemotherapy. Nine of these metabolites were subsequently tested for effects on HSPCs in vitro, but none of them exerted a clear concentration dependent effect on proliferation, immunophenotype and colony forming unit formation. Taken together, serum profiles of miRNAs and metabolites changed after chemotherapy. Rather than individually, these factors may act in concert to recruit HSPCs into action for hematopoietic regeneration.