Cryopreserved Cord Blood Units Research Articles

Long-Term Stability of Cord Blood Units After 29 Years of Cryopreservation: Follow-Up Data From the José Carreras Cord Blood Bank.

The José Carreras Cord Blood Bank (CBB) located in Düsseldorf as of today stores 21 215 active cryopreserved cord blood units (CBUs) applicable as a source for hematopoietic stem cell (HSC) transplantation. Since the success of transplantation outcomes is mainly dependent on the cord blood quality, typical parameters are evaluated by a Stability Monitoring Program specified by the FACT Standards. The longest expiration time determined to date is 29 years for unseparated units, 25 years for manual and 18 years for automated volume-reduced units licensed by the Paul-Ehrlich Institute. According to the CBB stability program TNC count, TNC recovery, TNC viability, CD34+7AAD- viability, CD45+7AAD- viability and CFC count were determined for all 3 processing methods applied over time. As a measure of stability, unseparated units (processed 1993-1998) revealed a mean TNC viability of 88.91 ± 5.01% after 29 years of cryopreservation versus manual volume-reduced CBUs (processed 1998-2005) with a mean of 84.22 ± 10.02% after 25 years of cryopreservation versus automated volume-reduced CBUs (processed since 2005) with a mean of 88.64.91 ± 3.91% after 18 years of cryopreservation. In addition, these relevant parameters were retrospectively analyzed for released transplants in correlation to the storage time. Moreover, the follow-up data of recipients from CBUs cryopreserved directly (unseparated) versus CBUs cryopreserved after manual versus automated volume-reduction are presented here demonstrating an earlier engraftment in both volume-reduced groups as compared to unseparated CBUs. By this retrospective analysis, key questions are discussed regarding cord blood parameters in relation to processing methods, engraftment, and patient age (children and adults).

Insights into highly engraftable hematopoietic cells from 27-year cryopreserved umbilical cord blood

Umbilical cord blood transplantation is a life-saving treatment for malignant and non-malignant hematologic disorders. It remains unclear how long cryopreserved units remain functional, and the length of cryopreservation is often used as a criterion to exclude older units. We demonstrate that long-term cryopreserved cord blood retains similar numbers of hematopoietic stem and progenitor cells compared with fresh and recently cryopreserved cord blood units. Long-term cryopreserved units contain highly functional cells, yielding robust engraftment in mouse transplantation models. We also leverage differences between units to examine gene programs associated with better engraftment. Transcriptomic analyses reveal that gene programs associated with lineage determination and oxidative stress are enriched in high engrafting cord blood, revealing potential molecular markers to be used as potency markers for cord blood unit selection regardless of length of cryopreservation. In summary, cord blood units cryopreserved for extended periods retain engrafting potential and can potentially be used for patient treatment.

Abstract 13 Long-Term Stability of Dus Cord Blood Units After >29 Years of Cryopreservation: Follow-Up Data from the José Carreras Cord Blood Bank

Abstract Introduction The José Carreras Cord Blood Bank (CBB) located in Düsseldorf stores 21215 active cryopreserved cord blood units (CBUs) and has released 1476 CBUs for allogeneic transplantation. The success of transplantations, but also the generation of cells for regenerative medicine for e.g. iPSC reprogramming, significantly depends on the quality of the cryopreserved CBUs after thaw. Objectives Therefore, typical parameters like cell count, recovery and viability are analysed from thawed CBUs yearly by a stability monitoring program according to the FACT standards. The longest cryopreservation period in liquid nitrogen tested to date is 338 months (>29 years) for unseparated units and 300 months (25 years) for volume-reduced units that are licensed by the Paul-Ehrlich Institute. Methods A retrospective analysis of unseparated CBUs processed from 1993-1997, CBUs processed from 1998-2005 by manual volume-reduction and CBUs processed since 2005 by automated volume-reduction applying the Sepax100 system was performed. In consideration of the distinct processing methods, storage time and existing follow-up data of released transplants, this approach should demonstrate the high CBU quality and proof the long-term engrafting capability of CBUs cryopreserved in liquid nitrogen. Results According to the CBB stability program means of TNC count (16.32±2.61 x 108), TNC recovery after thaw (106.8±13.91%, above 100% due to earlier applied cell-count method), TNC viability (88.91±5.01%), CD34+7AAD- viability (90.73±3.69%), CD45+7AAD- viability (69.09±5.38%) and CFC count (7.10±2.45 x 106) were determined after >29 years of cryopreservation for unseparated CBUs. In volume-reduced CBUs the mean TNC count (9.37±2.14 x 108), TNC recovery (97.78±3.70%), TNC viability (84.22±10.02%), CD34+7AAD- viability (88.11±5.16%), CD45+7AAD- viability (73.67±8.31%) and CFC count (1.37±0.59 x 106) were determined after 25 years of cryopreservation. Discussion In addition, these relevant parameters were retrospectively analyzed for released transplants in correlation to the storage time. The follow-up data of recipients from CBUs demonstrate an earlier engraftment of volume-reduced CBUs as compared to unseparated CBUs in accordance to an increased TNC count over time. With regard to applied processing methods, engraftment time and patient age (children and adults) this retrospective analysis confirms the high quality of old CBUs stored in the liquid phase at -196°C.

Recovery of Highly Functional Human Hematopoietic Stem and Progenitor Cells from 27-Year Old Cryopreserved Umbilical Cord Blood

Umbilical cord blood (CB) is a promising source of hematopoietic stem cells (HSCs) and progenitor cells (HPCs) for hematopoietic cell transplantation (HCT). CB is cryopreserved following collection, allowing for the amassment of nearly 800,000 CB units in public banks and an estimated 4 million in private banks. Cryopreservation of CB is essential for successful CB transplantation, and it is critical to understand how long CB can be stored with efficient recovery of engraftable HSCs. Prior work demonstrated efficient recovery of engraftable HSCs from 10-, 15-, and 21-year old cryopreserved CB. Here, we demonstrate efficient recovery of highly engraftable HSCs from 27-year old cryopreserved CB units. 3 CB units cryopreserved for >27 years were thawed with clinical protocols, and total nucleated cells were recovered with 76-87% viability. 3-6 fresh CB units were used as a comparison for cryopreserved units. Immunophenotyping assays to determine numbers of HSCs/HPCs showed that cryopreserved CB units had on average 4.25x103 CD34+ cells per 1x106 nucleated low density CB cells (LDCB), similar to fresh CB with 4.55x103CD34+ per 1x106 LDCB. Within the CD34+ population, cryopreserved CB when compared to fresh CB had on average equal or greater numbers of stringently immunophenotypically defined HSCs (9.1x103 vs 6.2x103), multipotent progenitors (MPPs) (2.1x105 vs 8.6x104), and multilymphoid progenitors (MLPs) (1.9x104 vs 1.0x104) per 1x106 CD34+ cells. Conversely, there were fewer numbers of common myeloid progenitors (CMPs) (2.9x104 vs 1.1x105), megakaryocyte-erythroid progenitors (MEPs) (4.5x104 vs 1.0x105), and granulocyte macrophage progenitors (GMPs) (4.8x104 vs 1.4x105). Colony forming unit (CFU) assays demonstrated that cryopreserved CB units exhibited lower functional HPC numbers per 1x106 CD34+ enriched cells including CFU-GM (1.9x104 vs 8.3x104), BFU-E (1.2x104 vs 3.4x104), and CFU-GEMM (1.1x104 vs 5.8x104). In ex vivo analysis of HSC/HPC proliferative capacity, cryopreserved CB units showed similar or greater capacity for expansion in growth stimulating media compared to fresh CB, including HSCs (7.7-fold vs 6.2-fold increase), MPPs (3.5-fold vs 4-fold increase), MLPs (44-fold vs 1.7-fold increase), CFU-GM (29-fold vs 13.3-fold increase), and CFU-GEMM (28.6-fold vs 4-fold increase). For in vivo functional HSC analysis, 10,000 CD34+ enriched cells were transplanted to sublethally irradiated NSG mice. Cryopreserved CB units exhibited early and late human engraftment in peripheral blood (PB) at months 1, 2, 4, and 5. Bone marrow (BM) human chimerism at month 5 ranged from low (0.5%) to robust levels of engraftment (52.7%). Limiting dilution analysis revealed that 2 cryopreserved CB units had similar SCID repopulating cell (SRC) frequency, ranging from 314 to 1392 SRCs per 1x106 CD34+ cells while the third had a much lower 65 to 393 SRCs per 1x106 CD34+ cells. The third CB unit also exhibited lower average human chimerism in the BM (0.55%) than the other 2 units (15% and 16.2%). However, the SRC frequencies in all 3 CB units are similar to those in fresh CB units published by our group and others (range 51 to 929 SRCs per 1x106 CD34+ cells). Secondary transplants showed that all 3 CB units have secondary repopulation capacity demonstrated by human chimerism in PB. These data suggest functional HSCs with short- and long-term engrafting and sustained self-renewal capacity can be cryopreserved for at least 27 years. We show that different cryopreserved CB units contain variable functional HSC frequency. Similar results in ex vivo characterization suggest cryopreservation is not the cause of these functional differences, but rather there were functional differences in the CB units prior to cryopreservation. This underscores the need to have reliable measures of CB functionality prior to cryopreservation for more efficient selection of donor units and to test potential effects of cryopreservation on individual units. Transcriptomic studies are ongoing to determine molecular programs that may contribute to differences in SRC frequency. These data will provide insight into mechanistic explanations for differences in HSC function in different CB units. Authors’ note: This project was conceived by the authors prior to the death of Hal E. Broxmeyer. Dr. Broxmeyer initiated the study as a continuation of his life's work demonstrating the utility of CB for HCT. This work is dedicated to Hal.

Results of a Multicenter Evaluation of a Rapid Flow Cytometry Potency Assay for Cryopreserved Cord Blood Units: A BEST Collaborative Study

Results of a Multicenter Evaluation of a Rapid Flow Cytometry Potency Assay for Cryopreserved Cord Blood Units: A BEST Collaborative Study

High Integrity and Fidelity of Long-Term Cryopreserved Umbilical Cord Blood for Transplantation.

Umbilical cord blood (UCB) is used as a source of donor cells for hematopoietic stem cell (HSC) transplantation. The success of transplantation is dependent on the quality of cord blood (CB) units for maximizing the chance of engraftment. Improved outcomes following transplantation are associated with certain factors of cryopreserved CB units: total volume and total nucleated cell (TNC) count, mononuclear cell (MNC) count, and CD34+ cell count. The role of the storage period of CB units in determining the viability and counts of cells is less clear and is related to the quality of cryopreserved CB units. Herein, we demonstrate the recovery of viable TNCs and CD34+ cells, as well as the MNC viability in 20-year-old cryopreserved CB units in a CB bank (MEDIPOST Co., Ltd., Seongnam-si, Gyeonggi-do, Korea). In addition, cell populations in CB units were evaluated for future clinical applications. The stable recovery rate of the viability of cryopreserved CB that had been stored for up to 20 years suggested the possibility of uses of the long-term cryopreservation of CB units. Similar relationships were observed in the recovery of TNCs and CD34+ cells in units of cryopreserved and fresh CB. The high-viability recovery of long-term cryopreserved CB suggests that successful hematopoietic stem cell (HSC) transplantation and other clinical applications, which are suitable for treating incurable diseases, may be performed regardless of long-term storage.

Enumerating regulatory T cells in cryopreserved umbilical cord blood samples using FOXP3 methylation specific quantitative PCR.

Allogeneic haematopoietic cell transplantation (HCT) is a curative therapy for severe haematological disorders. However, it carries significant risk of morbidity and mortality. To improve patient outcomes, better graft selection strategies are needed, incorporating HLA matching with clinically important graft characteristics. Studies have shown that the cellular content of HCT grafts, specifically higher ratios of T regulatory (Tregs)/T cells, are important factors influencing outcomes when using adult peripheral blood mobilised grafts. So far, no equivalent study exists in umbilical cord blood (CB) transplantation due to the limitations of cryopreserved CB samples. To establish the most robust and efficient way to measure the Treg content of previously cryopreserved CB units, we compared the enumeration of Treg and CD3+ cells using flow cytometry and an epigenetic, DNA-based methodology. The two methods were assessed for their agreement, consistency and susceptibility to error when enumerating Treg and CD3+ cell numbers in both fresh and cryopreserved CB samples. Epigenetic enumeration gave consistent and comparable results in both fresh and frozen CB samples. By contrast, assessment of Tregs and CD3+ cells by flow cytometry was only possible in fresh samples due to significant cell death following cryopreservation and thawing. Epigenetic assessment offers significant advantages over flow cytometry for analysing cryopreserved CB; similar cell numbers were observed both in fresh and frozen samples. Furthermore, multiple epigenetic assessments can be performed from DNA extracted from small cryopreserved CB segments; often the only CB sample available for clinical studies.

Efficient and Clinical-Grade Compatible Expansion of Endothelial Progenitors from Cryopreserved Cord Blood Units

Efficient and Clinical-Grade Compatible Expansion of Endothelial Progenitors from Cryopreserved Cord Blood Units

Total nucleated cell counts are driving clinician's choice rather than cryopreservation period: Lesson for cord blood banks

According to the increase in both the number of cryopreserved cord blood (CB) units and the cryopreservation period for each CB unit in the largest public CB bank in Korea, we are pursuing greater efficiency in CB bank management. Thus, we analyzed whether the cryopreservation period has a negative impact on the selection of CB units for CB transplantation (CBT). Until December 2019, 468 CB units were used for transplantation. The cryopreservation period, total nucleated cell (TNC), and CD34+ cell counts were analyzed among the CB units according to the CBT-year and the donation year. The results showed that the cryopreservation period was increased in recent CBT-year groups. The transplanted CB units showed similar TNC counts irrespective of the donation year, and the mean TNC count was 13.9 × 108/unit. CB units cryopreserved for a relatively long period were transplanted consistently. The mean TNC count of CB units cryopreserved for over 10 years was 16.4 × 108/unit. The mean CD34+ cell counts were not significantly different among the CB units transplanted after CBT-2013 and among the CB units donated after CBT-2011. Through an analysis of the CB units selected by clinicians for CBT, this study revealed that clinicians placed more weight on the TNC counts than on the cryopreservation period of cryopreserved CB units. Therefore, the minimum TNC count of CB units suitable for cryopreservation should be increased up to 13.0 × 108/unit to balance the satisfaction of clinicians’ needs with the efficiency of the CB bank.

Transient warming affects potency of cryopreserved cord blood units

Background aims. Cryopreserved cord blood units (CBUs) can be exposed to transient warming events (TWEs) during routine banking operations, which may affect their potency. NetCord-FACT guidelines recommend removal of these CBUs from inventory. The objective of this work was to evaluate warming kinetics of frozen CBUs in different settings to determine the optimal working environment and define the impact of different TWE scenarios on CB post-thaw quality and potency. MethodsThe warming kinetics of frozen CBUs was influenced by both working surfaces and ambient working temperature, with cold plates providing better protection than vinyl or metal surfaces. Measurement of time for required operational activities revealed that CBUs are probably exposed to core temperatures greater than –150°C even when cold plates are used to reduce warming rates. ResultsOn the basis of the warming kinetics and observed operational activities, three TWE causing scenarios (control, typical, worst case) were investigated using a pool-and-split design and cell viability, recovery and potency (colony-forming unit [CFU]) assays were performed. TWEs were found to have little impact on the recovery of total nucleated cells or on the viability of CD34+ cells. In contrast, the viability and recovery of CD45+ cells in the smaller CBU compartments were reduced by TWEs. Moreover, the worst-case TWE reduced CFU recovery from CBUs, whereas the typical-scenario TWE had little effect. Conclusions. Our results demonstrate that the distal segment underestimates the viability and potency of CBUs and that TWEs can affect the post-thaw viability and potency of CBUs. Although TWEs are almost inevitable during cord-blood banking operations, their effects must be diminished by reducing exposure time, using cold plates and strict operational protocols, to prevent worst-case TWEs.

Usefulness of the Hematopoietic Stem Cell Donor Pool as a Source of HLA-Homozygous Induced Pluripotent Stem Cells for Haplobanking: Combined Analysis of the Cord Blood Inventory and Bone Marrow Donor Registry.

Induced pluripotent stem cells (iPSCs) have opened up unprecedented opportunities for novel therapeutic options for precision medicine. Hematopoietic stem cell (HSC) donor pools with previously determined HLA types may be ideal sources for iPSC production. Based on the HLA distribution of cryopreserved cord blood units (CBUs) and registered bone marrow (BM) donors, we estimated how much of the Korean population could be covered by HLA-homozygous iPSCs. We analyzed a total of 143,866 Korean HSC donors (27,904 CBUs and 115,962 BM donors). Each donor sample was typed for the HLA-A, -B, and -DRB1 alleles at low to intermediate resolution by DNA-based molecular techniques: PCR sequence-specific oligonucleotide (PCR-SSOP), PCR with sequence-specific primers (PCR-SSP) and PCR with sequence-based typing (PCR-SBT). We also identified individuals possessing homozygous HLA haplotypes by direct counting. The matching probabilities for zero-mismatch transplantation were calculated for 143,866 Koreans and 50 million potential Korean patients. Among the HSC donor pool, 17 HLA-A alleles, 41 HLA-B alleles, and 13 HLA-DRB1 alleles, as well as 128 homozygous HLA-A-B-DRB1 haplotypes, were identified at serologic equivalents, and those haplotypes cumulatively matched 93.20% of the 143,866 Korean donors as zero HLA-mismatch iPSC sources. Among the combinations of 2,056 haplotypes with frequencies ≥ 0.001% in a population of 50 million, those 128 homozygous haplotypes can provide 93.65% coverage for potential Korean recipients. Haplobanking of a reasonable number of HLA-A, -B, and -DRB1 homozygous iPSC lines derived from CBUs and cells of registered BM donors may be an efficient option for allogenic iPSC therapy.

Cord blood–derived cytokine-induced killer cells combined with blinatumomab as a therapeutic strategy for CD19+ tumors

BackgroundCytokine-induced killer cells (CIKs) are an advanced therapeutic medicinal product (ATMP) that has shown therapeutic activity in clinical trials but needs optimization. We developed a novel strategy using CIKs from banked cryopreserved cord blood units (CBUs) combined with bispecific antibody (BsAb) blinatumomab to treat CD19+ malignancies. MethodsCB-CIKs were expanded in vitro and fully characterized in comparison with peripheral blood (PB)–derived CIKs. ResultsCB-CIKs, like PB-CIKs, were mostly CD3+ T cells with mean 45% CD3+CD56+ and expressing mostly TCR(T cell receptor)αβ with a TH1 phenotype. CB-CIK cultures had, however, a larger proportion of CD4+ cells, mostly CD56−, as well as a greater proportion of naïve CCR7+CD45RA+ and a lower percentage of effector memory cells, compared with PB-CIKs. CB-CIKs were very similar to PB-CIKs in their expression of a large panel of co-stimulatory and inhibitory/exhaustion markers, except for higher CD28 expression among CD8+ cells. Like PB-CIKs, CB-CIKs were highly cytotoxic in vitro against natural killer (NK) cell targets and efficiently lysed CD19+ tumor cells in the presence of blinatumomab, with 30–60% lysis of target cells at very low effector:target ratios. Finally, both CB-CIKs and PB-CIKs, combined with blinatumomab, showed significant therapeutic activity in an aggressive PDX Ph+ CD19+ acute lymphoblastic leukemia model in NOD-SCID mice, without sign of toxicity or graft-versus-host disease. The improved expansion protocol was finally validated in good manufacturing practice conditions, showing reproducible expansion of CIKs from cryopreserved cord blood units with a median of 28.8 × 106 CIK/kg. DiscussionWe conclude that CB-CIKs, combined with bispecific T-cell–engaging antibodies, offer a novel, effective treatment strategy for leukemia.

A new strategy for umbilical cord blood collection developed at the first Colombian public cord blood bank increases total nucleated cell content.

The total nucleated cell dosage of umbilical cord blood (UCB) is an important factor in determining successful allogeneic hematopoietic stem cell transplantation after a minimum human leukocyte antigen donor-recipient match. The northern South American population is in need of a new-generation cord blood bank that cryopreserves only units with high total nucleated cell content, thereby increasing the likelihood of use. Colombia set up a public cord blood bank in 2014; and, as a result of its research for improving high total nucleated cell content, a new strategy for UCB collection was developed. Data from 2933 collected and 759 cryopreserved cord blood units between 2014 and 2015 were analyzed. The correlation of donor and collection variables with cellularity was evaluated. Moreover, blood volume, cell content, CD34+ count, clonogenic capacity, and microbial contamination were assessed comparing the new method, which combines in utero and ex utero techniques, with the conventional strategies. Multivariate analysis confirmed a correlation between neonatal birth weight and cell content. The new collection method increased total nucleated cell content in approximately 26% and did not alter pre-cryopreservation and post-thaw cell recovery, viability, or clonogenic ability. Furthermore, it showed a remarkably low microbial contamination rate (1.2%). The strategy for UCB collection developed at the first Colombian public cord blood bank increases total nucleated cell content and does not affect unit quality. The existence of this bank is a remarkable breakthrough for Latin-American patients in need of this kind of transplantation.

Comparison of two methodologies for the enrichment of mononuclear cells from thawed cord blood products: The automated Sepax system versus the manual Ficoll method

Background aimsUmbilical cord blood (CB) is being used as a source of hematopoietic stem cells (HSCs) and immune cells to treat many disorders. Because these cells are present in low numbers in CB, investigators have developed strategies to expand HSCs and other immune cells such as natural killer (NK) cells. The initial step in this process is to enrich mononuclear cells (MNCs) while depleting unwanted cells. The manual method of MNC enrichment is routinely used by many centers; however, it is an open system, time-consuming and operator dependent. For clinical manufacturing, it is important to have a closed system to avoid microbial contamination. MethodsIn this study, we optimized an automated, closed system (Sepax) for enriching MNCs from cryopreserved CB units. ResultsUsing Sepax, we observed higher recovery of total nucleated cells (TNC), CD34+ cells, NK cells and monocytes when compared to manual enrichment, despite similar TNC and CD34+ viability with the two methods. Even though the depletion of red blood cells, granulocytes and platelets was superior using the manual method, significantly higher CFU-GM were obtained in MNCs enriched using Sepax compared to the manual method. This is likely related to the fact that the automated Sepax significantly shortened the processing time (Sepax: 74 – 175 minutes versus manual method: 180 – 290 minutes). The use of DNAse and MgCl2 during the Sepax thaw and wash procedure prevents clumping of cells and loss of viability, resulting in improved post-thaw cell recovery. DiscussionWe optimized enrichment of MNCs from cryopreserved CB products in a closed system using the Sepax which is a walk away and automated processing system.

Long-Term Quality Control Program Plan for Cord Blood Banks in Korea: A Pilot Study for Cryopreservation Stability.

BackgroundMaintaining the quality of cryopreserved cord blood is crucial. In this pilot study, we describe the results of the internal quality control program for a cord blood bank thus far.MethodsDonated cord blood units unsuitable for transplantation were selected for internal quality control once a month. One unit of cord blood, aliquoted into 21 capillaries, was cryopreserved and thawed annually to analyze the total nucleated cell count, CD34+ cell count, cell viability test, and colony-forming units assay.ResultsNo significant differences in the variables (total nucleated cell count, cell viability, CD34+ cell count) were observed between samples cryopreserved for one and two years. Upon comparing the variables before cryopreservation and post thawing with the capillaries of one year of storage, cell viability and CD34+ cell counts decreased significantly. The use of cord blood samples in capillaries, which can be easily stored for a long period, was similar to the methods used for testing segments attached to the cord blood unit.ConclusionsThe results of this study may be useful for determining the period during which the quality of cryopreserved cord blood units used for transplantation is maintained.

Small-Molecule Ice Recrystallization Inhibitors Improve the Post-Thaw Function of Hematopoietic Stem and Progenitor Cells.

The success of hematopoietic stem cell transplantation depends in part on the number and the quality of cells transplanted. Cryoinjuries during freezing and thawing reduce the ability of hematopoietic stem and progenitor cells (HSPCs) to proliferate and differentiate after thawing. Up to 20% of the patients undergoing umbilical cord blood (UCB) transplant experience delayed or failed engraftment, likely because of the inadequate hematopoietic potency of the unit. Therefore, the optimization of cryopreservation protocols, with an emphasis on the preservation of HSPCs, is an important issue. Current protocols typically utilize a 10% dimethyl sulfoxide cryoprotectant solution. This solution ensures 70–80% post-thaw cell viability by diluting intracellular solutes and maintaining the cell volume during cryopreservation. However, this solution fails to fully protect HSPCs, resulting in the loss of potency. Therefore, a new class of cryoprotectants (N-aryl-d-aldonamides) was designed and assessed for the ability to inhibit ice recrystallization and to protect HSPCs against cryoinjury. Several highly active ice recrystallization inhibitors were discovered. When used as additives to the conventional cryoprotectant solution, these nontoxic small molecules improved the preservation of functionally divergent hematopoietic progenitors in the colony-forming unit and long-term culture-initiating cell assays. By contrast, structurally similar compounds that did not inhibit ice recrystallization failed to improve the post-thaw recovery of myeloid progenitors. Together, these results demonstrate that the supplementation of cryopreservation solution with compounds capable of controlling ice recrystallization increases the post-thaw function and potency of HSPCs in UCB. This increase may translate into reduced risk of engraftment failure and allow for greater use of cryopreserved cord blood units.

Establishing the UCB graft potentiality

In this issue of Blood, Shoulars et al demonstrate the validity and reliability of a novel potency assay based on multiparameter flow cytometric enumeration of cells expressing aldehyde dehydrogenase (ALDH), CD45, and CD34 in tubing segments attached to cryopreserved cord blood units (CBUs) and its relevance to clinical practice.1

Autologous Cord Blood Infusion for the Treatment of Brain Injury in Children with Cerebral Palsy

Background: Cerebral palsy (CP) results from in utero or perinatal injury to the developing brain, often through stroke, hypoxic insult, or hemorrhage. Current treatments are supportive, focusing on managing sequelae with physical therapies, medications, and surgery. However, there are no therapies to address the underlying brain injury. Umbilical cord blood (CB) has been shown to prevent neurologic damage in children with leukodystrophiesand to improve motor function in animal models of brain injury and CP. Previously, we demonstrated safety of intravenous autologous CB infusion in young children with brain injuries. The Cerebral Palsy-Autologous Cord Blood (CP-AC) study was designed to assess the efficacy of a single intravenous infusion of autologous CB in young children with spastic CP.Methods: The CP-AC study is a prospective, randomized, double blind, placebo controlled crossover study of a single intravenous infusion of autologous CB in children ages 1-6 years with spastic CP. The Gross Motor Classification System (GMFCS) was utilized to classify the level of motor function at study entry and follow-up. Children were eligible if they were (1) GMFCS level 2-4 or (2) GMFCS level 1 with hemiplegia if they used their affected hand as an assist only. Children with known genetic conditions, intractable seizures, or severe microcephaly were ineligible. Autologous CB units had to have a documented pre-cyropreservation total cell dose of ≥1x107/kg, negative sterility culture, negative maternal infectious disease screening, and confirmed identity through HLA typing of the subject and a segment attached to the CB unit. Subjects were evaluated at baseline, one year, and two years with functional evaluations (Gross Motor Function Measure-66 (GMGM-66), Peabody Developmental Motor Scales-2, Assisting Hand Assessment, Bayley Scales of Infant Development) and brain MRI. They were randomized to the order in which they received CB and placebo infusions (given one year apart). The primary endpoint was change in GMFM-66 score at one year after the initial infusion (CB or placebo). Cryopreserved CB units were shipped to and stored at Duke until the day of treatment when they were thawed and washed in dextran 40 +5% human serum albumin (DA). Infusions, dosed at 1-5x107/kg based on the pre-cryopreservation total nucleated cell count (TNCC) and diluted in 1.25mL/kg of DA, were administered intravenously over 5-10 minutes in the outpatient setting after premedication with oral acetaminophen, IV Benadryl, and IV Solumedrol. Subjects received IV fluids and were monitored for 2-4 hours post-infusion.Results: Sixty-three children were enrolled with a median age of 2 years (range 1- 6) at baseline. Median TNCC of CB infusion was 2x107/kg (range 0.4-5) with a median CD34 dose of 0.5x105/kg (range 0.05-4). Despite negative pre-cryopreservation cultures, one CB unit grew β-hemolytic strepfrom a sample of the thawed CB unit. There were no clinical infections in this or any other study patient. One subject had transient infusion reactions consisting of hives +/- low-grade fever after each infusion; an additional dose of Benadryl was administered after the first reaction. Preliminary analysis of the 63 patients at one year showed no statistically significant overall difference in GMFM-66 change scores between placebo and treated groups (6.9 vs. 7.5, p =0.72). However, treated subjects who received pre-cryopreservation cell doses of >2.5x107/kg demonstrated statistically significant improvement in GMFM-66 change scores compared to subjects who received lower cell doses (p <0.01). A similar result was observed comparing subjects who received above (or below) the median infused cell dose of 1.98x107/kg (p =0.05) (Figure 1). The infused cell dose was not related to type of CP (p =0.32) or severity (p=0.46).Conclusions: When adequately dosed, cord blood may improve motor function in young children with spastic CP. We observed improvement at pre-cryopreservation cell doses (>2.5x107/kg) that correspond with the minimum cell dose used for hematopoietic reconstitution in patients undergoing allogeneic CB transplantation. In order to extend this therapy to children who do not have adequate autologous CB units available, safety and efficacy of allogeneic CB products should be investigated. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Plasma CC-chemokine ligand 28 level is correlated with hematopoietic stem cells in human cord blood.

CC-chemokine ligand 28 (CCL28) was previously identified as a novel growth factor in vitro for hematopoietic stem cells (HSCs) from cord blood (CB). However, there is no report on the relationship between CCL28 and HSCs in a human body. To reveal the effect of CCL28 on hematopoietic cells in human CB at birth, we measured CCL28 in frozen CB plasma, which was preserved as a reference sample for cryopreserved CB units for HSC transplantation. We also evaluated the correlation of CCL28 level with CB components. A total of 81 cryopreserved nonconforming CB units for transplantation were selected. The level of CCL28 was 2540 ± 377 pg/mL. The CCL28 levels correlated with the number of CD34+ cells (r = 0.222, p = 0.047) and white blood cells (r = 0.254, p = 0.022) in the CB units. The CCL28 levels also correlated with hemoglobin levels (r = 0.221, p = 0.048) in fresh CB. This finding of positive correlation between CCL28 level and CD34+ cell numbers in vivo, together with the previous report that CCL28 influences the proliferation of hematopoietic cells in CB in vitro, may give a clue for better understanding the variability in HSC content in CB that is cryopreserved for HSC transplantation.

Is there an expiration date for a cord blood unit in storage?

With improving expertise and supportive care, cord blood (CB) transplants are now associated with outcomes comparable to unrelated and sibling donor transplants.1 There is a need to increase the size and diversity of international CB inventories and to retain cryopreserved CB units for as long as safely possible. There are in vitro data supporting >90% recovery of hematopoietic progenitor cells from frozen CB cells stored for up to 12 years,2 and data showing that progenitor cell recoveries from short-term freeze samples ranging from 2 to 8 weeks are comparable to those cryopreserved for 10–15 years.3,4 Broxmeyer et al.5 reported adequate recovery (80–100%) of granulocyte–macrophage and multi-potential hematopoietic progenitors from functional CB units cryopreserved for up to 23.5 years as well as recovery of viable progenitor cells from CBs frozen for 15 years, which were able to generate CD45+ human cell engraftment when infused into sublethally irradiated NOD-SCID mice and were comparable to that reported with fresh CB.6 Despite this in vitro evidence, transplant physicians still remain concerned about the possible loss of integrity of frozen CB units associated with longer durations of storage.7 In one report, the incidence of bag breaks over a 6.5-year period was 3.5%, where 75% of the breaches occurred in units that had been cryopreserved for >2 years.7 Therefore, it is important to determine whether prolonged time of cryopreservation and storage may adversely affect clinical transplant outcomes, and with the new US Food and Drug Administration licensing regulations for CB units this question has become even more relevant: ‘is there an expiration date for CB unit in storage?’.