A simple and reliable procedure for cord blood banking, processing, and freezing: St Louis and Ohio Cord Blood Bank experiences

Umbilical cord blood quality and quantity: Collection up to transplantation

Umbilical cord blood (UCB) is an attractive source of hematopoietic stem cells for transplantation in some blood disorders. One of the major factors that influence on transplantation fate is cord blood (CB) cell count, in addition to human leukocyte antigen similarity and CD34+ cell number. Here, we review the factors that could effect on quality and quantity of CBUs. Relevant English-language literatures were searched and retrieved from PubMed using the terms: CB, quality, collection, and transplantation. The numbers of total nucleated cells (TNCs) and CD34+ cells are good indicators of CB quality because they have been associated with engraftment; thereby, whatever the TNCs in a CB unit (CBU) are higher, more likely they led to successful engraftment. Many factors influence the quantity and quality of UCB units that collect after delivery. Some parameters are not in our hands, such as maternal and infant factors, and hence, we cannot change these. However, some other factors are in our authority, such as mode of collection, type and amount of anticoagulant, and time and temperature during collection to postthaw CBUs and freeze-and-thaw procedures. By optimizing the CB collection, we can improve the quantity and quality of UCB for storage and increase the likelihood of its use for transplantation.

High quality cord blood banking is feasible with delayed clamping practices. The eight-year experience and current status of the national Swedish Cord Blood Bank

The National Swedish Cord Blood Bank (NS-CBB) is altruistic and publicly funded. Herein we describe the status of the bank and the impact of delayed versus early clamping on cell number and volume. Cord Blood Units (CBUs) were collected at two University Hospitals in Sweden. Collected volume and nucleated cell content (TNC) were investigated in 146 consecutive Cord Blood (CB) collections sampled during the first quarter of 2012 and in 162 consecutive CB collections done in the first quarter of 2013, before and after clamping practices were changed from immediate to late (60 s) clamping. NS-CBB now holds close to 5000 units whereof 30 % are from non-Caucasian or mixed origins. Delayed clamping had no major effect on collection efficiency. The volume collected was slightly reduced (mean difference, 8.1 ml; 95 % CI, 1.3-15.0 ml; p = 0.02), while cell recovery was not (p = 0.1). The proportion of CBUs that met initial total TNC banking criteria was 60 % using a TNC threshold of 12.5 × 10(8), and 47 % using a threshold of 15 × 10(8) for the early clamping group and 52 and 37 % in the late clamping group. Following implementation of delayed clamping practices at NS-CBB; close to 40 % of the collections in the late clamping group still met the high TNC banking threshold and were eligible for banking, implicating that that cord blood banking is feasible with delayed clamping practices.

Cord blood collection and processing with hydroxyethyl starch or non-hydroxyethyl starch

BACKGROUND

Collection and processing characteristics influencing quality of cord blood (CB) units play an essential role to cord blood banks (CBBs). At many CBBs, volume reduction is performed using hydroxyethyl starch (HES) and the Sepax (Biosafe) automated cell processing system. Due to the withdrawal of HES from the European market, a validation of the nonHES protocol was performed.

METHODS

This partially retrospective study identified CB characteristics such as gestational age and CB volume/cell count correlated with higher quality. For the nonHES validation, CB was analyzed for total nucleated cell (TNC), mononuclear cell (MNC) recovery, hematocrit (HCT) and colony-forming units (CFUs). Viabilities of CD34(+) and CD45(+) cells were determined by 7-aminoactinomycin D (7-AAD) and AnnexinV (AnnV) staining and compared for 21 mL and 42 mL buffy coat (BC) samples applying the HES/nonHES protocol.

RESULTS

Factors affecting the potency of CB transplants were the gestational age and the volume reduction to a defined BC volume. High initial cell counts and CB volumes correlated negatively with post-processing TNC recovery for lower BC volumes. Post-processing HES and nonHES results were comparable, but nonHES revealed a significantly lower post-thaw recovery of viable CD34(+) cells measured by 7-AAD/AnnV (21 mL: 45.4 ± 16.4%; 42 mL: 67.3 ± 14.5%) as compared with HES (21 mL: 72.7 ± 14.4%, P = 0.0164; 42 mL: 83.4 ± 14.7%, P = 0.0203).

DISCUSSION

Due to the lower post-thaw CD34(+) cell viability (AnnV(-)/7-AAD(-)) for nonHES samples, the use of HES is recommended, ideally combined with a high BC volume. The post-processing HCT has no statistically significant impact on the post-thaw CD34(+) cell viability (AnnV(-)/7-AAD(-)).

Postthaw characterization of umbilical cord blood: markers of storage lesion

BACKGROUND

The continued growth in the uses of umbilical cord blood (UCB) will require the development of meaningful postthaw quality assays. This study examines both conventional and new measures for assessing UCB quality after long-term storage.

STUDY DESIGN AND METHODS

The first arm of the study involved thawing UCB in storage for short (approx. 1 year) and long periods of time (>11 years). Conventional postthaw measures (colony-forming units [CFU], total nucleated cell counts, CD34+45+) were quantified in addition to apoptosis. The second arm of the study involved taking units stored in liquid nitrogen and imposing a storage lesion by storing the units in -80°C for various periods of time. After storage lesion, the units were thawed and assessed.

RESULTS

In the first arm of the study, there was little difference in the postthaw measures between UCB stored for short and long periods of time. There was a slight increase in the percentage of CD34+45+ cells with time in storage and a reduction in the number of cells expressing apoptosis markers. When moved from liquid nitrogen to -80°C storage, the nucleated cell count varied little but there was a distinct decrease in frequency of CFUs and increase in percentage of cells expressing both early and late markers of apoptosis.

CONCLUSION

Nucleated cell counts do not reflect damage to hematopoietic progenitors during long-term storage. Expression of caspases and other markers of apoptosis provide an early biomarker of damage during storage, which is consistent with other measures such as CFU and percentage of CD34+45+ cells.

Current thawing and infusion practice of cryopreserved cord blood: the impact on graft quality, recipient safety, and transplantation outcomes

Methods of handling, thawing, and infusion of cord blood (CB) products vary substantially among thaw/transplant centers (TCs). This review 1) compares currently available CB product types and thaw methods recommended by CB banks (CBBs), 2) discusses causes of inconsistency in thaw method application at TCs, 3) advises elements to consider in thaw method approval or selection at the TC, 4) provides a procedural template for the traditional thaw methods, and 5) suggests acceptable time from product thaw to infusion and other considerations for safe infusion. It also compares postinfusion adverse reaction and engraftment data as functions of thaw methods. Remarks and suggestions made throughout this review are: 1) not intended to supersede manufacturer's instructions but meant to support the standardization of preparative procedures recommended by CBBs and 2) intended to help TCs to investigate relevant quality issues and handle challenges, especially when the TC is unable to follow recommendations due to foreseeable technical, quality, and/or clinical factors.

Impact of storage temperature and processing delays on cord blood quality: discrepancy between functional in vitro and in vivo assays

BACKGROUND

Optimal conditions of cord blood (CB) storage, processing, cryopreservation, and thawing are critical for banking and transplantation. Nevertheless, standardized procedures are still awaited.

STUDY DESIGN AND METHODS

We evaluated the impact of preprocessing storage and temperature on recovery, viability, and functional differentiation capacities of hematopoietic progenitor cells. We compared units stored at room temperature (RT) or at 4 °C for 72 hours before cryopreservation to units processed shortly after collection (<12 hr).

RESULTS

Postthaw results showed similar in vitro characteristics between immediate processing and 4 °C storage for cell recovery and viability, both significantly higher than RT storage. Surprisingly, we demonstrated that storage of CB units at RT before processing and cryopreservation profoundly altered in vivo hematopoietic reconstitution in mice, although in vitro hematopoietic colony-forming unit potential was unaltered.

CONCLUSION

Our findings challenge current CB storage practices and suggest standard in vitro quality assessments may not always be indicative of CB engraftment potential.

Analysis of 120 pediatric patients with nonmalignant disorders transplanted using unrelated plasma-depleted or -reduced cord blood

BACKGROUND

Unrelated cord blood (CB) is an important stem cell source for unrelated hematopoietic cell transplantation (HCT) of patients with nonmalignant disorders. Processing methods to prepare red blood cell-reduced CB units incur significant nucleated cell loss. In contrast, plasma depletion or reduction (PDR) processing of CB units entails the removal of only a portion of the plasma with minimal nucleated cell loss. However, there are relatively limited data regarding outcomes of CB transplants using units processed by PDR.

STUDY DESIGN AND METHODS

A Center for International Blood and Marrow Transplant Research (CIBMTR)-audited analysis was performed on 120 pediatric patients with nonmalignant disorders transplanted between November 2001 and January 2008 at 29 US and 17 international centers using PDR CB units from two CB banks.

RESULTS

Transplant characteristics were as follows: median age, 3.5 years (range, 0.1-14 years); median patient weight, 15 kg (range, 4-61 kg); 58% male; HLA matches (intermediate-resolution HLA-A and HLA-B and high-resolution HLA-DRB1) of the units used in these patients six of six in 26, five of six in 48, four of six in 47, and three of six or two of six in 6; median prefreeze total nucleated cell dose, 10.5×10(7)/kg; median prefreeze CD34+ dose, 3.7×10(5)/kg; and nonmyeloablative regimen in 24%. The median times to myeloid and platelet engraftment were 21 and 49 days, respectively. The cumulative incidence of reported Grade II to IV acute graft-versus-host disease (aGVHD) was 38±5%, and 19±4% had Grade III to IV aGVHD. The Kaplan-Meier estimates of 3-year transplant-related mortality, overall survival, and disease-free survival were 20±4, 79±4, and 70±6%, respectively.

CONCLUSION

These data demonstrate the effectiveness of PDR CB units for HCT.

Cell recovery comparison between plasma depletion/reduction- and red cell reduction-processing of umbilical cord blood

BACKGROUND AIMS

Limited cell dose has hampered the use of cord blood transplantation (CBT) in adults. One method of minimizing nucleated cell loss in cord blood (CB) processing is to deplete or reduce plasma but not red blood cells - plasma depletion/reduction (PDR).

METHODS

The nucleated cell loss of PDR was studied, and determined to be less than 0.1% in the discarded supernatant plasma fraction in validation experiments. After testing and archival sampling, the median nucleated cell recovery for PDR processing was 90%, and median CD34(+) cell recovery 88%. In a CB bank inventory of 12 339 products with both pre- and post-processing total nucleated cells (TNC), PDR processing resulted in median post-processing TNC recoveries of 90.0% after testing and archival samples removal. Using the same 10 CB units divided into two halves, we compared directly the recovery of PDR against hydroxyethyl starch red cell reduction (RCR) for TNC, CD34(+) cells and colony-forming units (CFU-GM, CFU-E, CFU-GEMM and total CFU) after parallel processing. We also compared the loss of very small embryonic-like stem cells (VSEL).

RESULTS

We demonstrated significantly higher recoveries using PDR for TNC (124%), CD34(+) cells (121%), CFU-GM (225%), CFU-GEMM (201%), total CFU (186%) and VSEL (187%). The proportion of high TNC products was compared between 10 912 PDR and 38 819 RCR CB products and found to be 200% higher for products that had TNC ≥150 × 10(7) (P = 0.0001) for the PDR inventory.

CONCLUSIONS

Our data indicate that PDR processing of CB provides a significantly more efficient usage of this valuable and scarce resource.

Mislabeled units of umbilical cord blood detected by a quality assurance program at the transplantation center

We instituted procedures to check the identity of cord blood unit provided for transplantation by carrying out ABO and human leukocyte antigen (HLA) typing of the thawed units before transplantation. ABO typing is done using standard techniques. Rapid HLA class I serology is with monoclonal antibody trays (One Lambda Inc) using standard incubations. One mislabeled umbilical cord blood (UCB) unit was detected on the day of intended transplantation by repeat ABO typing of the thawed unit at our transplantation center. Because ABO typing will not detect all labeling errors, the rapid serologic class I HLA typing procedure was done on thawed units just before transplantation for all units without an attached segment. This procedure identified a second mislabeled unit. In a 6-year period, 2 of 871 (0.2%) cord blood units sent to us for transplantation were mislabeled and potentially would have been transplanted incorrectly. This error rate of 1 per 249 (0.4%) patients could have potentially devastating consequences.

Consistency of the initial cell acquisition procedure is critical to the standardization of CD34+ cell enumeration by flow cytometry: results of a pairwise analysis of umbilical cord blood units and cryopreserved aliquots

BACKGROUND

The CD34+ cell content is a predictive factor for engraftment and survival after umbilical cord blood (UCB) transplantation. The high variability in the CD34 assay results in different recommended cell doses for infusion across transplant centers and also limits the clinical utility of the CD34+ cell counts provided by cord blood banks (CBBs). This bi-institutional study was intended to understand the sources of this variability.

STUDY DESIGN AND METHODS

The level of CD34 agreement between the University of Minnesota (UM) and the Madrid CBB (MCBB) was evaluated on 50 UCB units before and after cryopreservation. Two cryopreserved vials per unit were thawed and processed at both laboratories. Dual-platform ISHAGE-based flow cytometry was used for CD34 enumeration.

RESULTS

Postthaw nucleated cell recoveries were similar. However, whereas CD34+ cell enumeration before freezing was 0.35 +/- 0.22 percent, the results after thawing were 0.98 +/- 0.65 and 0.57 +/- 0.39 percent at UM and MCBB, respectively. Bland-Altman plots analysis ruled out the interchangeability of MCBB and UM CD34 values. Differences in the initial cell acquisition settings accounted for most of the CD34 discrepancy, which was no longer present after normalization of the forward scatter threshold for cell acquisition.

CONCLUSIONS

The standardization of CD34+ cell enumeration by flow cytometry is strongly reliant on a consistent initial cell acquisition procedure. The interlaboratory variation can be minimized by using frozen cell aliquots as reference samples. Both requisites should be considered for CD34 testing and UCB unit selection by regulatory institutions involved with cord blood banking and transplantation.

Ethnically mismatched cord blood transplants in African Americans: the Saint Louis Cord Blood Bank experience

BACKGROUND

For ethnic minority patients where a suitably matched BM or peripheral blood donor is frequently unavailable, cord blood offers an opportunity for hematopoietic stem cell transplantation. Focused recruitment of ethnic minorities for cord blood donation has been proposed as the preferred strategy to improve access for minority recipients to cord blood for transplantation. The aim of this study was to evaluate cord blood characteristics for Caucasian and African American donors and the success of ethnically mismatched UC blood transplantation in African American recipients.

METHODS

Retrospective data analysis was performed comparing the characteristics of 556 cord blood units from African American and Caucasian donors. The outcomes of 18 African American ethnically mismatched transplant recipients were compared with a paired sample of 18 ethnically matched Caucasian recipients.

RESULTS

The fraction of collected units meeting acceptability criteria from African Americans was significantly lower compared with Caucasians (P = <0.0001). Additionally, African Americans had a significantly lower post-processing total nucleated cell count (TNC) compared with Caucasians (P=0.007) but there were no other significant differences in conventionally measured product characteristics. In the transplant analysis, there was no difference in overall survival at 1 year (P=0.85) or time to neutrophil engraftment (P=0.92) between the two patient populations.

DISCUSSION

At comparable levels of TNC dose and HLA matching, the use of ethnically mismatched UC blood units as a source for allogeneic unrelated transplant can result in successful transplant outcomes for African American patients.

Transgene expression after stable transfer of a mammalian artificial chromosome into human hematopoietic cells

OBJECTIVE

The transfer of mammalian artificial chromosomes (MACs) to hematopoietic stem and progenitor cells (HSPCs) presents a promising new strategy for ex vivo gene therapy that alleviates numerous concerns surrounding viral transduction along with a unique platform for the systematic study of stem cell biology and fate. Here we report the transfer of a satellite DNA-based artificial chromosome (an ACE), made in mouse cells, into human cord blood hematopoietic cells.

MATERIALS AND METHODS

A GFP-Zeo-ACE encoding the genes for humanized Renilla green fluorescence protein (hrGFP) and zeomycin resistance (zeo) was transferred into CD34 positively selected cord blood cells using cationic reagents.

RESULTS

Post ACE transfer, CFU-GM-derived colonies were generated in methylcellulose in the presence or absence of bleomycin. Bleomycin-resistant cells expressed GFP and contained intact autonomous ACEs, as demonstrated by fluorescent in situ hybridization. Moreover, when the cells from these plates were replated in methylcellulose, we observed secondary bleomycin-resistant CFU-GM-derived colonies, demonstrating stable chromosome retention and transgene function in a CFU-GM progenitor.

CONCLUSION

To our knowledge this is the first report demonstrating the transfer of a mammalian artificial chromosome and the stable expression of an encoded transgene in human hematopoietic cells.

Cell loss and recovery in umbilical cord blood processing: a comparison of postthaw and postwash samples

BACKGROUND

Engraftment after umbilical cord blood (UCB) transplantation is highly dependent on nucleated cell (NC) and CD34+ cell content. Current standard postthaw (PT) processing includes a wash step to remove dimethyl sulfoxide (DMSO), lysed red cells, and stroma. The contribution of the wash step to cell loss and ultimately the dose of cells available for transplant have yet to be systematically reported. This study examines the effect of the wash step as well as that of PT storage on various quality control variables of UCB units.

STUDY DESIGN AND METHODS

Ten units were thawed and washed based on the New York Blood Center method. Samples were removed from each unit at six time points: prefreeze (PF), immediately PT, immediately postwash (PW), and 1, 2, and 5 hours PW. On each sample, total nucleated cell (TNC) count, CD34+ cell enumeration, colony-forming unit (CFU)-granulocyte-macrophage, and viability assays (fluorescence microscopy [acridine orange/propidium iodide, or AO/PI] and flow cytometry [7-aminoactinomycin]) were obtained.

RESULTS

TNC counts decreased PT and at subsequent time points; the PT TNC recovery was 89 percent compared to 82 percent PW (p < 0.01). TNC recovery decreased to 90 percent of PW (82% of PT) values (p < 0.01) and 83 percent of PW (76% of PT) values (p < 0.001), at 2 and 5 hours PW, respectively. CD34+ cell loss PT was not significant. Viability by AO/PI decreased PT and plateaued over time. In contrast, viability by flow cytometry remained higher and increased slightly over time. CFUs were significantly lower PT, recovering PW.

CONCLUSIONS

Our data indicate that the thawing and washing results in a substantial loss of cells, with TNC loss approaching 20 percent when compared with PF counts; the wash step was responsible for nearly half of the cell loss. The reduced PT viability was expected. Elapse of time PW resulted in further loss of NCs but no detectable significant changes in CD34+ cell content and viability and/or CFU.

A closed system for the clinical banking of umbilical cord blood

Umbilical cord blood (UCB) is a source of hematopoietic progenitor cells and is used as an alternative to the bone marrow or peripheral blood for treatment of several onco-hematological diseases. Because of the limited number of CD34+ hematopoietic stem cells present in UCB units and of the elevated costs of cryopreservation, it is of paramount importance to select the UCB units that are clinically useful before storage and optimize banking efficiency by designing reliable procedures to process and freeze the selected units. Among the different parameters characterizing UCB, nucleated cell (NC) and CD34+ cell content provides useful criteria to select UCB units since clinical data documented that the infused cell load (both NC and CD34+ cells) plays an important role in the successful outcome of transplants. By evaluating volume, CD34+ cell content, NC total amount, and NC density of 117 UCB units, we found a significant association between CD34+ cell content and NC density and total amount, indicating these parameters as useful to decide UCB clinical utility. Furthermore, we set up a fast procedure to process UCB units for storage. A system for NC separation and volume reduction of UCB samples in a dedicated, germ-free, closed circuit was developed, where plasma and red blood cells (RBC) depletion was obtained by sedimentation in the presence of a 3.5% Polygeline solution. By this separation system, both RBC depletion and high NC and CD34+ cell recoveries were achieved in 60 min, and the yield was comparable to the one obtained by other separation methods. Since Polygeline has been clinically used as a plasma expander and no toxic effects on patients were reported, the protocol can be applied in the large-scale banking of UCB.

[Cord blood banking: public versus private banks--facts to ponder and consider]

Since 1988, allogeneic cord blood transplantations have been used in the hematology and oncology area. Cord blood banks, either public or from non-profit corporations, opened in several countries. They organized themselves into a world-wide network permitting broad and quick graft availability all over the world. Cryopreservation modalities and biological safety were strongly defined according to laboratory good practices. More recently, in the United States, Canada and some European and Asian countries, commercial companies created for-profit cord blood banks. They offer families the possibility of privately storing the cord blood of their children. Then, if a child gets sick and needs a hematopoietic stem cell transplantation, it is possible to use the cord blood for an autograft. These companies present this service, relatively expensive for the families, as a true biological insurance. Also, they capitalize on families' hopes that scientific progress will increase cord blood autografts and other stem cell medical applications. In this work, we review available scientific data, ethical considerations and laws that can contribute to an informed reflection.

In utero or ex utero cord blood collection: which is better?

BACKGROUND

The relative nucleated cell count of umbilical cord blood (CB) correlates with improved engraftment and survival. This study compares two collection methods to assess CB content, including cell numbers.

STUDY DESIGN AND METHODS

The Massachusetts CB bank used trained obstetricians and midwives to collect CB in utero before the delivery of the placenta. The banks in California, Ohio, Oregon, and Minnesota used trained American Red Cross (ARC) personnel who collected CB ex utero after the delivery of the placenta. All banks processed CB by RBC sedimentation and volume reduction.

RESULTS

The volume and total nucleated cell count of collected CB before processing, as well as after processing CFU-GM and CD34+ cells, showed no advantage of either method. In utero collections resulted in more rejections of collected units (due to labeling problems, bacterial contamination, clotting, and delay between collection and processing) than ex utero collections. There were fewer medical exclusions after in utero collection.

CONCLUSION

CB can be collected successfully using either the in utero or ex utero methods; both methods produce comparable nucleated cell, MNC, CD34+, and CFU-GM numbers. Bacterial contamination, low volume, clotting, and delay until processing are generally higher with in utero collection.