Cord blood banking: volume reduction of cord blood units using a semi-automated closed system

Next generation sequencing of 11 HLA loci characterises a diverse UK cord blood bank

The introduction of next generation sequencing (NGS) for stem cell donor registry typing has contributed to faster identification of compatible stem cell donors. However, the successful search for a matched unrelated donor for some patient groups is still affected by their ethnicity. In this study, DNA samples from 714 National Health Service (NHS) Cord Blood Bank donors were typed for HLA-A, -B, -C, -DRB1, -DRB345, -DQA1, -DQB1, -DPA1 and -DPB1 by NGS. Analysis of the ethnic diversity showed a high level of diversity, with the cohort comprising of 62.3% European and 37.7% of either multi-ethnic or non-European donors, of which 12.3% were multi-ethnic. The HLA diversity was further confirmed using PyPop analysis, 405 distinct alleles were observed in the overall NHS-CBB cohort, of which 37 alleles are non-CWD, including A*31:14N, B*35:68:02, C*14:23 and DQA1*05:10. Furthermore, HLA-DQA1 and HLA-DPA1 analysis showed 12% and 10%, respectively, of the alleles currently submitted to IMGT, confirming further diversity of the NHS-CBB cohort. The application of 11 HLA loci resolution by NGS revealed a high level of diversity in the NHS-CBB cohort. The incorporation of this data coupled with ethnicity data could lead to improved donor selection, contributing to better clinical outcomes for patients.

Dual-wavelength oblique back-illumination microscopy for the non-invasive imaging and quantification of blood in collection and storage bags

There is currently no low-cost method to quantitatively assess the contents of a blood bag without breaching the bag and potentially damaging the sample. Towards this end, we adapt oblique back-illumination microscopy (OBM) to rapidly, inexpensively, and non-invasively screen blood bags for red blood cell (RBC) morphology and white blood cell (WBC) count. OBM has been recently introduced as a tomographic technique that produces high-resolution wide-field images based on phase-gradient and transmission. Here we modify this technique to include illumination at dual wavelengths to facilitate spectral analysis for cell classification. Further, we apply a modified 2D Hilbert transform to recover the phase information from the phase-gradient images for facile cell segmentation. Blood cells are classified as WBCs and RBCs, and counted based on shape, absorption spectrum, and phase profile using an automated algorithm. This work has important implications for the non-invasive assessment of (1) cell viability in storage bags for transfusion applications and (2) suitability of a cord blood collection bag for stem cell therapy applications.

Effects of Cryopreservation Duration on the Outcome of Single-Unit Cord Blood Transplantation

Cryopreservation is widely used in umbilical cord blood (UCB) banking, yet its impact on progenitor cell function remains largely unaddressed. It is unknown whether long-term cryopreservation affects UCB transplantation outcomes. Herein, we evaluated the impact of UCB age on clinical outcomes and investigated the effect of cryopreservation duration of UCB on hematopoietic potency in 91 patients receiving single cord blood transplantations. UCB cryopreservation duration was 0.7 to 13.4 y. The most common indication of transplant was thalassemia (48%). There was no significant association between cryopreservation duration and neutrophil engraftment probability (P = 0.475). Cryopreservation duration did not affect the post-thaw viability and subsequent neutrophil engraftment rate. Therefore, UCB units can undergo cryopreservation for at least 8 y with no impact on clinical outcomes.

Cryopreservation in Closed Bag Systems as an Alternative to Clean Rooms for Preparations of Peripheral Blood Stem Cells

Autologous and allogeneic stem cell transplantation (SCT) represents a therapeutic option widely used for hematopoietic malignancies. One important milestone in the development of this treatment strategy was the development of effective cryopreservation technologies resulting in a high quality with respect to cell viability as well as lack of contamination of the graft.Stem cell preparations have been initially performed within standard laboratories as it is routinely still the case in many countries. With the emergence of cleanrooms, manufacturing of stem cell preparations within these facilities has become a new standard mandatory in Europe. However, due to high costs and laborious procedures, novel developments recently emerged using closed bag systems as reliable alternatives to conventional cleanrooms. Several hurdles needed to be overcome including the addition of the cryoprotectant dimethylsulfoxide (DMSO) as a relevant manipulation. As a result of the development, closed bag systems proved to be comparable in terms of product quality and patient outcome to cleanroom products. They also comply with the strict regulations of good manufacturing practice.With closed systems being available, costs and efforts of a cleanroom facility may be substantially reduced in the future. The process can be easily extended for other cell preparations requiring minor modifications as donor lymphocyte preparations. Moreover, novel developments may provide solutions for the production of advanced-therapy medicinal products in closed systems.

Optimal method for collection of umbilical cord blood: an Egyptian trial for a public cord blood bank

BACKGROUND

Umbilical cord blood (UCB) contains stem cells and can be used as an alternative to bone marrow transplantation. Engraftment is dependent on the total nucleated cell (TNC) and CD34+ cell counts of the cord blood units. This study was designed to evaluate the effect of the method of collection of the UCB on the yield of the cord blood units.

STUDY DESIGN AND METHODS

Informed consent was obtained from 100 eligible mothers for donation of cord blood. Both in utero and ex utero methods were used for collection. The cord blood volume was measured. The TNC and the CD34+ cell counts were enumerated.

RESULTS

We have found that in utero collection gave significantly larger volumes of cord blood and higher TNC counts than ex utero collection. There was no significant difference between both methods regarding the CD34+ cell counts. This study revealed a significant correlation between the volume of the collected cord blood and both TNC and CD34+ cell counts.

CONCLUSION

It is better to collect cord blood in utero before placental delivery to optimize the quality of the cord blood unit.

Optimization of microbial screening for cord blood

BACKGROUND

Collection and processing of cord blood (CB) is associated with significant risk of contamination; hence standards mandate microbial screening of the final product. The sensitivity of current methods to evaluate the microbial content of CB is unknown, given the small volume tested and reduced sensitivity of pediatric bottles. Hence, this study was undertaken to evaluate an optimal microbial screening method.

STUDY DESIGN AND METHODS

CB was collected using a closed system then spiked with organisms at 1 or 10 colony-forming units (CFUs)/mL. Samples were screened using culture bottles (BacT/ALERT, bioMérieux; and BACTEC, Becton Dickinson). Several methods were evaluated with different combinations of inoculated bottles (adult vs. pediatric), sample types (plasma discard, red blood cell [RBC] discard, or final product), and sample volumes.

RESULTS

Of 94 cord blood units (CBUs) spiked with organisms before screening, 81% tested positive for contamination overall. Screening of CB in pediatric bottles resulted in equivalent detection rates on the BacT/ALERT and BACTEC systems (33% at 1 CFU/mL and 73% at 10 CFUs/mL, respectively). However, the pediatric bottle screen only detected 15% of obligate anaerobes. A combined fraction method showed superior detection (71%) compared to the plasma fraction (27%) and resulted in optimal anaerobic detection.

CONCLUSIONS

This study demonstrates that the optimal microbial screening method for CB includes testing a combination of discard fractions (plasma and RBCs) in addition to final product using an automated culture system. Inoculating a small sample of final product in a pediatric bottle is suboptimal for microbial detection and may lead to distribution of contaminated CB for transplantation.

Qualitative and quantitative cell recovery in umbilical cord blood processed by two automated devices in routine cord blood banking: a comparative study

BACKGROUND

Volume reduction is a widely used procedure in umbilical cord blood banking. It concentrates progenitor cells by reducing plasma and red blood cells, thereby optimising the use of storage space. Sepax and AXP are automated systems specifically developed for umbilical cord blood processing. These systems basically consist of a bag processing set into which cord blood is transferred and a device that automatically separates the different components during centrifugation.

METHODS

The aim of this study was to analyse and compare cell recovery of umbilical cord blood units processed with Sepax and AXP at Valencia Cord Blood Bank. Cell counts were performed before and after volume reduction with AXP and Sepax.

RESULTS

When analysing all the data (n =1,000 for AXP and n= 670 for Sepax), the percentages of total nucleated cell recovery and red blood cell depletion were 76.76 ± 7.51% and 88.28 ± 5.62%, respectively, for AXP and 78.81 ± 7.25% and 88.32 ± 7.94%, respectively, for Sepax (P <0.005 for both variables). CD34(+) cell recovery and viability in umbilical cord blood units were similar with both devices. Mononuclear cell recovery was significantly higher when the Sepax system was used.

DISCUSSION

Both the Sepax and AXP automated systems achieve acceptable total nucleated cell recovery and good CD34(+) cell recovery after volume reduction of umbilical cord blood units and maintain cell viability. It should be noted that total nucleated cell recovery is significantly better with the Sepax system. Both systems deplete red blood cells efficiently, especially AXP which works without hydroxyethyl starch.

Factors affecting microbial contamination rate of cord blood collected for transplantation

BACKGROUND

Collection and processing of cord blood (CB) is associated with significant risk of microbial contamination and hence relevant standards mandate microbial screening of the final product. This study aimed to determine the contamination rate and associated risk factors during 14 years of banking at the Sydney Cord Blood Bank.

STUDY DESIGN AND METHODS

CB was collected and processed using a closed system and tested for contamination using blood culture bottles (BacT/ALERT, bioMérieux) incubated for a minimum of 5 days. Four microbial screening methods were used with different combinations of inoculated bottles (adult or pediatric) and associated sample volumes (10 or 1 mL).

RESULTS

Of 13,344 CB units screened, 537 (4.0%) tested positive for contamination, with Bacteroides spp. (20.9%), Staphylococcus spp. (18.6%), and Propionibacterium spp. (13.7%) being the most common isolates. The contamination rate reduced from 10% in 1997 to 1.1% in 2009. Multivariate analysis demonstrated the following variables were independently associated with higher contamination rates: vaginal delivery, collection by obstetric staff, and use of an anaerobic bottle in addition to an aerobic bottle (which facilitated a larger sample inoculation volume than pediatric bottles).

CONCLUSIONS

This study demonstrates that contamination rates of CB collected for transplantation can be substantially reduced by collection after cesarean delivery and utilizing trained CB collection staff. These data also indicate that the common practice of testing using a pediatric (aerobic) bottle with its attendant small volume of the final CB product may be suboptimal for sensitive detection of contaminating anaerobic microbes.

A simple filtration system for red blood cell depletion and volume reduction in routine processing of human umbilical cord blood

BACKGROUND AND OBJECTIVES

Currently, stem cells and other progenitor cells are obtained from human umbilical cord blood (HUCB) using a variety of methods that are designed primarily for red blood cell depletion and volume reduction prior to freezing and storage. Some of these methods are very cumbersome and involve several steps that may result in significant cell loss. Therefore, processes that minimize the loss of haematopoietic stem and progenitor cells (HSPC) remains very critical. In the present study, we describe a simple filtration process for achieving both volume reduction and red blood cell depletion in a 'closed sterile system' with significant recovery of viable HSPC.

MATERIALS AND METHODS

About 80-100 ml of HUCB were collected into citrate-phosphate-dextrose-adenine 1 anticoagulant. Each HUCB was divided into 25-70-ml aliquots and then either diluted with isotonic saline or filtered without any prior dilution with an experimental Red Cell Volume Reduction System (RCVRS). The HSPCs were recovered by retrograde rinsing of the filter with an isotonic stem cell recovery solution. The viability, colony forming properties, leucocytes and CD34+ cells recoveries were determined.

RESULTS

The mean volume of the HUCB before processing was reduced from 43.9 +/- 7.9 ml to 11.8 +/- 0.7 ml (n = 55) with red blood cell depletion of 85.2 +/- 3.7%. Diluting the HUCB with isotonic saline prior to processing with RCVRS increased the red blood cell depletion to 91.9 +/- 3.0% (n = 7) without any significant loss in viability or cell recovery. The mean viability of the RCVRS-processed HUCB was not significantly different from the control unprocessed blood (96.60 +/- 1.90 vs. 96.63 +/- 2.12%; P > 0.05). The mean recoveries of the CD34+ and the haematopoietic clonogenic progenitor cells with the filter were 83.9 +/- 26.8 (n = 40) and 99.9 +/- 27.9% (n = 35), respectively.

CONCLUSION

The present results show that the RCVRS provides a simple and easy-to-use process for obtaining red blood cell depletion and volume reduction of HUCB with good cell viability and recoveries.

A new automatic device for routine cord blood banking: critical analysis of different volume reduction methodologies

BACKGROUND AIMS

Volume reduction is the usual process in cord blood banking that has some advantages regarding reducing the storage space and dimethyl sulfoxide (DMSO) quantity in the final product. The volume reduction methodology must guarantee high cell recovery and red blood cell (RBC) depletion by reducing all the umbilical cord blood (UCB) units to a standard volume.

METHODS

We analyzed and compared critically three different volume reduction methods [hydroxyethylstarch (HES), top and bottom with Optipress II and Compomat G4, and AXP] used at the Valencia Cord Blood Bank over 10 years.

RESULTS

The highest significant RBC depletion was achieved with the AXP system (P<0.001), while the top and bottom system with Compomat G4 and an adjusted buffy coat (BC) volume to 41 mL enabled the best total nucleated cell (TNC) recovery (P<0.001). TNC recovery and RBC depletion were similar for AXP and HES with an adjusted volume to 21 mL. In the multivariate analysis, when analyzing all cases, the BC volume set significantly influenced TNC, CD34+ and lymphocyte recoveries and RBC depletion (P<0.001). RBC depletion was significantly influenced by the initial volume and initial RBC content of UCB units (P<0.001).

CONCLUSIONS

AXP is a highly efficient method for RBC depletion, providing the same TNC recovery as HES method with a final volume of 41 mL. AXP has the advantages of being an automatic and functionally closed system that shortens and better standardizes the proceedings. Top and bottom is a closed system that allows better TNC recoveries when the BC volume set is 41 mL.

Ten-year quality control of a semiautomated procedure of cord blood unit volume reduction

BACKGROUND

Volume reduction of cord blood units decreases the cost of cryogenic storage. This study reports the analysis of a 10-year quality control program of a semiautomated cord blood volume reduction procedure.

STUDY DESIGN AND METHODS

Cord blood was collected in a plastic bag containing 29 mL citrate-phosphate-dextrose, centrifuged at 2124 x g for 12 minutes, and processed with a semiautomated device. The procedure was aimed at removing most red blood cells and plasma and concentrating hematopoietic progenitors in the buffy coat (BC), thus reducing the unit volume and saving cryogenic space. Finally, the BC was cryopreserved with an equal volume of 20 percent dimethyl sulfoxide. Total nucleated cells (TNCs) were counted before and after processing in the 4311 units banked from 1998 through 2007, whereas CD34+ cells and colony-forming units-granulocyte-macrophage (CFU-GM) were counted in 420 random units from 2001 through 2007.

RESULTS

Mean postvolume reduction annual recoveries of TNCs, CD34+ cells, and CFU-GM ranged from 82.8 +/- 12.3 (standard deviation) to 91.4 +/- 6.4 percent, from 87.8 +/- 14.1 to 95.2 +/- 23.8 percent, and from 101.5 +/- 51.4 to 117.8 +/- 59.5 percent, respectively. Very strong correlations were found (r > 0.87) between postprocessing versus preprocessing TNCs, CD34+ cells, and CFU-GM; a moderate correlation between initial TNC count and unit's volume (r = 0.51); and no correlation between TNC percentage of recovery in the BC and initial unit's volume. The latter data indicate that most TNCs concentrate in the BC.

CONCLUSIONS

The semiautomated procedure of cord blood unit volume reduction used in this study provides high and stable cellular recoveries during several years of routine cord blood banking.

Influence of volume reduction and cryopreservation methodologies on quality of thawed umbilical cord blood units for transplantation

INTRODUCTION

Although there is considerable variability in methodology among umbilical cord blood banks, their common goal is to achieve optimal product quality for transplantation. Cryopreservation is a critical issue for a long-term maintenance of cord blood viability and colony-forming capacities.

MATERIALS AND METHODS

We designed a prospective study to compare controlled (CRF) vs. non-controlled freezing (URF) of volume-reduced cord blood units. In addition, the influence of hydroxy ethyl starch (HES) on cryopreservation was also assayed. To assess the efficiency of protocols used, cell recoveries were measured and the presence of hematopoietic colony-forming units was quantified.

RESULTS

In the study phase, we observed similar CB haematopoietc recoveries for CRF and URF strategies, except for TNC recovery that was better for HES volume reduced CB units in the URF group. When we analysed the data of routine processed CB units in samples from satellite cryovials, we found better BFU-E, CFU-GM, CFU-GEMM and CFU recoveries for those units processed with HES than without HES, in an URF manner.

CONCLUSIONS

URF of CB units is a cryopreservation procedure that allows similar hematopoietic progenitor recoveries than CRF with programmed devices. However, our study suggests that those banks that cryopreserve CB units in a URF manner should use HES for volume reduction. On the other hand, for CRF cryopreservation methodology volume reduction with and without HES are equally useful.

Directed sibling cord blood banking for transplantation: the 10-year experience in the national blood service in England

Umbilical cord blood (UCB) is an important source of hematopoietic stem cells for transplantation. Although UCB is often collected from unrelated donors, directed umbilical cord blood (DCB) from sibling donors also provides an important source of UCB for transplantation. This report summarizes the experience in collection, testing, storage, and transplantation of DCB units by the National Blood Service for England and North Wales over 10 years. Eligibility for collection was based on an existing sibling suffering from a disease that may be treated by stem cell transplantation or a family history that could result in the birth of a sibling with a disease that could be treated by stem cell transplantation. Collections were made on the provision that the sibling's clinician was willing to financially support the collection and to take responsibility for medical review of the mother and potential recipient. Given the high investment in UCB banking and the introduction of new regulations and mandatory licensing under the European Union Tissues and Cells Directive and those proposed in the U.S., this report details the procedures that we have used for DCB donations, the outcome data where donations have been used for transplantation, and it provides some timely recommendations for best practices. Disclosure of potential conflicts of interest is found at the end of this article.

CD34+ progenitors are reproducibly recovered in thawed umbilical grafts, and positively influence haematopoietic reconstitution after transplantation

Cord blood (CB) units are increasingly used for allogeneic transplantation. Cell dose, a major factor for CB selection, is evaluated before freezing by each CB bank, using various techniques. This may introduce variability and affect the prediction of cell recovery after thawing, or haematopoietic reconstitution. Forty-two children were transplanted at the same institution with unrelated CB units. All units were thawed and evaluated at the same cell therapy facility, using standard procedures. We investigated: (i) factors that affect cell loss after thawing, and (ii) the importance of CD34(+) cell doses. Prefreeze and post-thaw CD34(+) cell doses were statistically correlated, thus suggesting that variability in numeration techniques used by different CB banks does not compromise the biological and clinical value of these figures. CD34(+) cell recovery appeared to be correlated with the absolute number of CD34(+) cells per frozen bag. Infused CD34(+) is the cell dose that better correlates with platelet reconstitution delay; in addition, when using a quartile comparison, haematopoietic recovery appeared to be related with prefreeze and post-thaw CD34(+) cell doses. We conclude that enumeration of CD34(+) cells in CB units is of biological significance, and may help select CB units and identify patients at risk of delayed recovery.

Cord blood volume reduction using an automated system (Sepax) vs. a semi-automated system (Optipress II) and a manual method (hydroxyethyl starch sedimentation) for routine cord blood banking: a comparative study

Background With the development of cord blood banking, solutions have to be found to solve the storage space problem, by reducing the volume of cord blood units (CBU). Methods We compared total nucleated cell (TNC) and CD34(+) cell counts before and after processing with three different CBU volume reduction methods used consecutively in our bank: a manual method based on hydroxyethyl starch sedimentation (HES) (n=447), a top-and-bottom (TB) semi-automated method (n=181) using Optipress II, and the Sepax automated method (n=213). Statistical analysis was done using t-tests, linear regression and Spearman correlation coefficients. Adjusted variables included TNC, CD34(+) cell counts, CD34(+) cell percentage and CB volume before processing. Results TNC recovery was higher with Sepax (80.3+/-7.7%) than with HES (76.8+/-9.1%) and TB (60.7+/-13.5%) (P<0.0001, both). It was higher with HES than with TB (P<0.0001). CD34(+) cell recovery was higher with Sepax (86+/-11.6%) than with HES (81.5+/-12.5%) and TB (82.0+/-17.7%) (P<0.008 and <0.0001, respectively) and results with HES and TB were not significantly different (P=0.7). Interestingly, with Sepax, TNC and CD34(+) cell recoveries were not correlated with pre-processing values (P=0.8 and 0.4, respectively). Discussion In conclusion, the Sepax volume reduction method allows higher TNC and CD34(+) cell recoveries.

Automated separation of cord blood units in top and bottom bags using the Compomat G4

Cord blood (CB) has become a real alternative source of haematopoietic stem cells for bone marrow reconstitution in a variety of malignant disorders. As a response to this increasing activity, CB banks have been developed to guarantee the quality of processed CB units. Volume reduction of CB units maximizes storage space and also has other advantages. The aim of this study was to develop a program for the volume reduction of CB in the Compomat G4 device. We also compared two different top and bottom systems for CB fractionation (Compomat G4 and Optipress II). We empirically designed three different programs for volume reduction of CB with Compomat G4: two for final BC volume of 41 ml (CB1 and CB2) and the other one for buffy coat (BC) volume of 25 ml (CB3). Significantly worse recoveries were achieved for CB processed with program CB3. A RBC depletion of >or=50%, >or=60% and >or=70% were achieved for 67%, 39% and 9% of all units respectively. When comparing Compomat G4 and Optipress II, total nucleated cell recovery was similar for both methods, while lymphocytes recovery was significantly better for Optipress II.

Multiple-laboratory comparison of in vitro assays utilized to characterize hematopoietic cells in cord blood

BACKGROUND

Understanding the variability in results obtained by multiple laboratories is important because cord blood units are distributed worldwide for transplantation.

STUDY DESIGN AND METHODS

Four exercises were conducted by multiple laboratories to assess assay variability on nucleated cell (NC), mononuclear cell (MNC) by hematology analyzers [HAs], and CD34+ cell (flow cytometry) measurements. Exercise 1 was an intralaboratory exercise in which the reproducibility of cell measurements was determined. Exercises 2 and 3 involved the shipment of identical processed cord blood samples. In Exercise 2, laboratory-specific methods were utilized. In Exercise 3, two commercial CD34+ cell methods (Stem-Kit and TruCOUNT) were used. In Exercise 4, CD34+ cell levels were determined on repetitive regating of identical list-mode files.

RESULTS

Intralaboratory reproducibility was highest for NC measurements and lowest for CD34+ cell measurements. In Exercise 2, all laboratories except one utilized HA with an impedance technology and determined comparable results for NC and MNC levels, whereas the other laboratory utilized a HA with an optical counting method. Substantial variation was observed on measuring CD34+ cells with ranges of 32 to 141, 32 to 66, and 25 to 116 CD34+ cells per microL for the three identical samples. In Exercise 3, on the use of one specific commercial assay, the ranges of CD34+ levels were 214 to 411 and 62 to 178 cells per microL for the two identical samples. Nearly all participating laboratories determined comparable CD34+ levels on the use of identical list-mode files.

CONCLUSION

These studies indicate that substantial variability in CD34+ cell levels were determined with flow cytometry. The variability in NC and MNC levels was minimal with HA methodology.

Multi-laboratory evaluation of procedures for reducing the volume of cord blood: influence on cell recoveries

BACKGROUND

Various procedures can be used to isolate stem and progenitor cells from cord blood. This study evaluated the hydroxyethyl starch sedimentation (HES) with two centrifugation steps, and the top and bottom (T&B) isolation of buffy coat following a single centrifugation, and two filter systems for processing cord blood, one developed by Asahi Kasei Medical (filter A) and the second by Terumo (filter B).

METHODS

Each of seven laboratories was randomly assigned the evaluation of either the HES or T&B method and one of the filter methods (n=8 cord blood units, per laboratory, for each method). The leukocyte-containing fraction with the stem/progenitor cells was recovered from the filters by reverse flushing. Utilizing the routine traditional processing and testing procedures of each laboratory, in vitro parameters were determined, with samples obtained after collection, after processing and after freezing/thawing. The results were expressed as the percentage recovery of viable cells in processed vs. collected samples (performance 1; PF1) and in thawed vs. processed samples (performance 2; PF2). The composite results obtained by the seven laboratories were summarized.

RESULTS

The median PF1 percentage recovery of total nucleated cells (TNC) was comparable with both traditional methods (HES 79%, T&B 86%) and statistically reduced with both filtration procedures (filter A 58%, filter B 61%). Mononuclear cell (MNC) PF1 recovery was highest statistically with the T&B method (91%) and reduced on using filter A (77%) and filter B (70%) and the HES method (72%). CD34+ cell recovery was judged to be essentially comparable with the four methods, although the range of unit recoveries differed. The percentage recovery of TNC and MNC in PF1 was influenced by the volume of the collected cord blood, especially with use of the filtration procedures. This correlated with TNC content. A greater percentage of red cells and platelets was removed during processing with both filter methods. The time to process cord blood preparations with filter A was significantly shorter than the other methods. Processing with the HES method took the longest time. The recoveries for TNC, MNC and CD34+ cells in PF2 did not appear to be influenced by the specific processing procedure.

DISCUSSION

These data indicate that filters that capture stem and progenitor cells may be an appropriate methodology for processing cord blood collected for banking.

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.

Red blood cell depletion with a semiautomated system or hydroxyethyl starch sedimentation for routine cord blood banking: a comparative study

BACKGROUND

The major problem with long-term cord blood (CB) banking is the required storage space. In this sense, many studies have been performed to establish techniques for volume reduction of CB units.

STUDY DESIGN AND METHODS

We compared two different methods for CB volume reduction in both development and routine phases: hydroxyethyl starch (HES) sedimentation and top-and-bottom fractionation with the Optipress II (Baxter Healthcare). Monitoring the total nucleated cell (TNC) count, lymphocytes, CD34+ cells, and colony-forming unit (CFU) content in both preprocess and postprocess CB units assessed the volume reduction process.

RESULTS

The CB units processed in both groups had comparable volume and cells counts before and after volume reduction, except for number of red blood cells (RBCs), which was significantly greater for the Optipress II group. Recoveries of CD34+ and RBC depletion were significantly better for the HES group. For routine processing, TNC and lymphocyte recoveries were significantly better for CB units processed by the Optipress II system. There was, however, significantly less depletion of RBCs for this group. The time required for CB processing with the Optipress II was significantly shorter than the time needed for volume reduction by addition of HES (25+/-5 min vs. 55+/-10 min).

CONCLUSION

The volume reduction method with the Optipress II is a closed time-saving system that allows good cell recoveries. In contrast, the main advantage of the HES method is the higher RBC depletion that influences CFU content. Reducing RBC content must be the object of further improvements for volume reduction using the Optipress II method.

Utility of bag segment and cryovial samples for quality control and confirmatory HLA typing in umbilical cord blood banking

Many cord blood (CB) banks have been established worldwide as a response to the increasing number of CB transplantations. In this study, we describe a quality control program in which the utility of an integral bag segment and cryovial containing aliquots of cryopreserved product as haematopoietic content control and HLA typing confirmation for CB units has been evaluated. For this purpose, every month one stored CB unit and its satellite cryovials were thawed and washed. Nucleated cell counts, viability and clonogenic assays were performed from the bag and cryovial before washing. After washing, total nucleated cell, CD34+ counts, viability, and clonogenic assays were performed from the bag. In order to assure the ability of bag segments to confirm hematopoietic potential of CB units, clonogenic assays and viability were performed from attached segments of 10 CB units and the results were compared with those from bags and cryovials. When comparing all variables between thawed bag and cryovial samples, they showed similar results. Mean colony-forming unit (CFU) content of segment samples was 118.8 +/- 93.72 x 10(4) that resulted similar to bags and cryovials haematopoietic content. In conclusion, the quality control system described in this paper demonstrates that CB units are processed preserving the quantity and quality of the progenitor cells. The contiguous segment haematopoietic content is representative of the final product.

Comparison of total nucleated cell measurements of UC blood samples using two hematology analyzers

BACKGROUND

The total nucleated cell (TNC) content of umbilical cord blood (UCB) units currently serves as the most important measure for determining suitability for transplantation. Hence it is important that TNC measurements are performed in an accurate manner. TNC content is evaluated routinely by hematology analyzers (HA) as WBC counts. The objective of the study was to compare TNC content utilizing two different HA, one utilizing an impedance channel and optical channel, and the other using only an optical channel.

METHODS

The HA utilized in this study used two different modes of operation for lysis, regular mode (RM) and extended lysis mode (ELM). Cell-Dyn 3200 (CD3.2) utilizes optical technology for WBC measurements, involving WBC optical count (WOC) and nuclear optical count (NOC), whereas the Cell-Dyn 3700 (CD3.7) utilizes both the impedance (WIC) and optical technology (WOC) for WBC measurements. TNC content was determined with 17 identical samples using CD3.2 in one laboratory and CD3.7 in the other laboratory. Cord blood samples processed to concentrate nucleated cells by either of the laboratories were sent by overnight courier and assays were performed on the same day by both laboratories.

RESULTS

For CD3.7, the WOC values were consistently lower than the WIC using the regular mode, but showed no significant differences (P>0.05). The WIC and WOC values were comparable on using the ELM and RM. For CD3.2, WOC values using RM and NOC values using ELM showed no significant differences (P>0.05), even though the WOC measurement was lower than the NOC values for most samples. The best comparison of TNC measurement between the two HA could be achieved by comparing CD3.7-WIC with CD3.2-NOC values. The results were equivalent (P>0.05) and 12 of 17 samples had equal to or less than 10% difference (mean 9.5%).

DISCUSSION

TNC measurements of UCB samples were essentially identical using the WIC channel of the Cell-Dyn 3700 and the NOC channel of the Cell-Dyn 3200.

The London Cord Blood Bank: analysis of banking and transplantation outcome

Cord blood units (n = 5500) stored at the London Cord Blood Bank, including 59 units transplanted into a high risk and heterogeneous group of patients, were analysed. Transplant outcome data was available for 44 patients with a median clinical follow-up of 14 months (range 3-44 months). Over 40% of the collected units were of ethnic minority origin with a median volume of 79 ml (range 40-240 ml) and a median total nucleated cell (TNC) count of 11.9 x 10(9)/l (range 10.0-24.8 x 10(9)/l). The average patient's weight was 28 kg (range 5-80 kg) and the median age was 8 years (range 0.7-40 years). The median number of nucleated cells infused was 4 x 10(7)/kg (range 1.10-16 x 10(7)/kg). Neutrophil engraftment of 0.5 x 10(9)/l was observed in 33 (74+/-%) patients with an average time of 28 days (range 11-60). The Kaplan-Meier estimate of acute graft-versus-host disease (grade II >) at day 100 was 37 +/- 7% and in 27 (62%) patients, it was grade I or absent. The overall survival and disease-free survival at 2 years was 49 +/- 8% and 41 +/- 8%, respectively. Two years after transplantation the survival rate was 69% and 54% for patients receiving a 6/6 or 5/6 HLA matched units, respectively. Infection was the main cause of transplanted related mortality in these patients.

Engraftment capacity of umbilical cord blood cells processed by either whole blood preparation or filtration

Umbilical cord blood (UCB) preparation needs to be optimized in order to develop more simplified procedures for volume reduction, as well as to reduce the amount of contaminating cells within the final stem cell transplant. We evaluated a novel filter device (StemQuick((TM))E) and compared it with our routine buffy coat (BC) preparation procedure for the enrichment of hematopoietic progenitor cells (HPCs). Two groups of single or pooled UCB units were filtered (each n = 6), or equally divided in two halves and processed by filtration and BC preparation in parallel (n = 10). The engraftment capacity of UCB samples processed by whole blood (WB) preparation was compared with paired samples processed by filtration in the nonobese diabetic/severe combined immunodeficient (NOD/SCID) mouse animal model. Filtration of UCB units in the two groups with a mean volume of 87.8 and 120.7 ml, respectively, and nucleated cell (NC) content of 9.7 and 23.8 x 10(8) resulted in a sufficient mean cell recovery for mononucleated cells ([MNCs] 74.2%-77.5%), CD34(+) cells (76.3%-79.0%), and colony-forming cells (64.1%-86.3%). Moreover, we detected a relevant depletion of the transplants for RBCs (89.2%-90.0%) and platelets ([PLTs] 77.5%-86.1%). In contrast, the mean depletion rate using BC processing proved to be significantly different for PLTs (10%, p = 0.03) and RBCs (39.6%, p < 0.01). The NC composition showed a highly significant increase in MNCs and a decrease in granulocytes after filtration (p < 0.01), compared with a less significant MNC increase in the BC group (p < 0.05). For mice transplanted with WB-derived progenitors, we observed a mean of 15.3% +/- 15.5% of human CD45(+) cells within the BM compared with 19.9% +/- 16.8% for mice transplanted with filter samples (p = 0.03). The mean percentage of human CD34(+) cells was 4.2% +/- 3.1% for WB samples and 4.5% +/- 3.2% for filter samples (p = 0.68). As the data of NOD/SCID mice transplantation demonstrated a significant engraftment capacity of HPCs processed by filtration, no negative effect on the engraftment potential of filtered UCB cells versus non-volume-reduced cells from WB transplants was found. The StemQuick((TM))E filter devices proved to be a useful tool for Good Manufacturing Practices conform enrichment of HPCs and MNCs out of UCB. Filtration enables a quick and standardized preparation of a volume-reduced UCB transplant, including a partial depletion of granulocytes, RBCs, and PLTs without the need for centrifugation. Therefore, it seems very probable that filter-processed UCB transplants will also result in sufficient hematopoietic reconstitution in humans.

Short-term liquid storage of umbilical cord blood

BACKGROUND

Processing and banking of umbilical cord blood requires the development of methods for short-term liquid storage. This study examines the conditions (temperature, time, and storage solution) for optimal storage of cord blood.

STUDY DESIGN AND METHODS

Cord blood obtained from normal donors was collected and divided into aliquots. Some of the aliquots were supplemented with a storage solution and undiluted cord blood was used as a control. MNC counts, percentage of cells that are CD34+45+, frequency of CFU-GM, and solution pH were monitored for up to 72 hours in storage at 4 degrees C and room temperature.

RESULTS

MNC counts, CD34+45+ cell recovery, and frequency of CFU-GM were all improved in samples diluted with a storage medium when compared to undiluted controls. MNC counts were higher when cells were stored at 4 degrees C. MNC counts and the frequency of CFU-GM were reduced at 72 hours when compared with 24 hours.

CONCLUSIONS

These results indicate that the recovery of cells from cord blood can be improved if samples are stored using a storage solution for 24 hours without significant cell losses. Some of the solutions determined to be effective in maintaining viability are approved for human applications, although not specifically cord blood preservation.

Associations among nucleated cell, CD34+ cell and colony-forming cell contents in cord blood units obtained through a standardized banking process

BACKGROUND AND OBJECTIVES

Nucleated cell content is one of the main components used when evaluating cord blood (CB) units for clinical use. However, other indicators of the haematopoietic potential of a CB unit, such as CD34+ cell and colony-forming cell (CFU-TOT) content, have also been investigated. The aim of this study was to determine whether the CD34+ cell content could be used in selecting CB collections for banking.

MATERIALS AND METHODS

The collection data, as well as cellular contents of 588 CB collections obtained using a standardized CB banking process, were analysed.

RESULTS

Altogether, 526 CB units from the 588 collections accepted for processing were included in international search registries. The volume collected was, as expected, 69 ml (range 28-116 ml). The correlation between total CD34+ cell and CFU-TOT (n = 88) content in the CB collection was higher (r = 0.87) than the correlation between the total nucleated cell and CFU-TOT content (r = 0.69, both P < 0.0001). The correlations of pre- and postvolume reduction values of the total nucleated cell and CD34+ cell numbers were highly significant (r = 0.96, P < 0.0001, both). The total CFU-TOT content of the CB collection correlated significantly with the total CD34+ cell content of the CB unit before cryopreservation (but after volume reduction) (r = 0.89, P < 0.0001).

CONCLUSIONS

CD34+ cell content predicts the haematopoietic potential of a CB unit better than nucleated cell content. Accordingly, the CD34+ cell content of CB could be used to select CB for banking purposes and for transplantation.

Cryopreservation of umbilical cord blood: 2. Tolerance of CD34(+) cells to multimolar dimethyl sulphoxide and the effect of cooling rate on recovery after freezing and thawing

Cryopreservation protocols for umbilical cord blood have been based on methods established for bone marrow (BM) and peripheral blood stem cells (PBSC). The a priori assumption that these methods are optimal for progenitor cells from UCB has not been investigated systematically. Optimal cryopreservation protocols utilising penetrating cryoprotectants require that a number of major factors are controlled: osmotic damage during the addition and removal of the cryoprotectant; chemical toxicity of the cryoprotectant to the target cell and the interrelationship between cryoprotectant concentration and cooling rate. We have established addition and elution protocols that prevent osmotic damage and have used these to investigate the effect of multimolar concentrations of Me(2)SO on membrane integrity and functional recovery. We have investigated the effect of freezing and thawing over a range of cooling rates and cryoprotectant concentrations. CD34(+) cells tolerate up to 60 min exposure to 25% w/w (3.2M) Me(2)SO at +2 degrees C with no significant loss in clonogenic capacity. Exposure at +20 degrees C for a similar period of time induced significant damage. CD34(+) cells showed an optimal cooling range between 1 degrees C and 2.5 degrees C/min. At or above 1 degrees C/min, increasing the Me(2)SO concentration above 10% w/w provided little extra protection. At the lowest cooling rate tested (0.1 degrees C/min), increasing the Me(2)SO concentration had a statistically significant beneficial effect on functional recovery of progenitor cells. Our findings support the conclusion that optimal recovery of CD34(+) cells requires serial addition of Me(2)SO, slow cooling at rates between 1 degrees C and 2.5 degrees C/min and serial elution of the cryoprotectant after thawing. A concentration of 10% w/w Me(2)SO is optimal. At this concentration, equilibration temperature is unlikely to be of practical importance with regard to chemical toxicity.

Nonobese diabetic-severe combined immunodeficient mice transplantation of volume-reduced and thawed umbilical cord blood transplants following closed-system immunomagnetic cell selection

BACKGROUND

Protocols for the expansion of human umbilical cord blood (UCB) progenitors begin with the selection of CD34+ cells from stored frozen and thawed units. Use of an immunomagnetic selection procedure within a closed blood bag system for volume-reduced UCB transplants was evaluated, and the influence of CD34 cell selection on in vivo engraftment potential was studied.

STUDY DESIGN AND METHODS

Eleven thawed buffy coat-processed UCB units were processed within a standard blood bag with a washing solution. In six independent experiments, the same dosage of 2 x 104 CD34+ cells from paired selected and nonselected samples was transplanted into NOD-SCID mice. In two experiments, cells from the negative fraction were also transplanted.

RESULTS

The purity of CD34+ cells after selection was correlated with the removal of supernatant after the first washing step and therefore with adequate removal of damaged or dead cells (r=0.86, p < 0.01). Mice transplanted with unselected UCB cells had more human cells within their marrow than animals transplanted with selected cells (8.6 +/- 5.9% selected group vs. 19.8 +/- 14.2% unselected group; p=0.04), whereas no engraftment could be observed transplanting cells from the two negative fractions. A higher percentage of human CD45+ cells in the unselected group were found to be positive for CD38, CD14, CD33, and CD19, indicating a higher potential for these unselected progenitors to differentiate into myeloid cells and B cells.

CONCLUSIONS

Processing of volume-reduced and thawed UCB transplants within a closed-bag system before immunomagnetic CD34+ cell selection allows for the preparation of CD34+ cells of significant purity at technically useful cell recoveries. However, these experiments indicate a potential impairment of engraftment capacity for the CD34+ cell-enriched fraction.

Expansion of megakaryocyte progenitors from cryopreserved leukocyte concentrates of human placental and umbilical cord blood in short-term liquid culture

Long-term severe thrombocytopenia following human placental and umbilical cord blood (CB) transplantation is a significant clinical problem. We studied the ex vivo expansion of megakaryocytic progenitor cells (CFU-Meg) from cryopreserved/thawed leukocyte concentrates (LC) of CB prepared by the Tokyo Cord Blood Bank protocol. The LC cells were cultured in serum-free culture medium supplemented with a combination of early-acting cytokines including thrombopoietin (TPO), flt3-ligand (FL), and stem cell factor (SCF). Combination of TPO plus FL, TPO plus SCF, and all of these cytokines together resulted in 8.9-, 7.7-, and 8.4-fold increases in CFU-Meg, respectively, by Day 5 of culture. Our results showed that this simple expansion strategy has the potential for expanding CFU-Meg from cryopreserved/thawed LC cells from CB.

Repopulating activities of human cord blood cells separated by a stem cell collection filter in NOD/SCID mice: a comparative study of filter method and HES method

BACKGROUND

Volume reduction and removal of RBCs are essential for cost-efficient cord blood (CB) banking. It has previously been shown that a newly developed device, a stem cell-collection filter (SCCF), can reduce the CB volume and remove RBCs efficiently, giving high recovery rates for CD34+ cells, colony-forming cells, and long-term culture-initiating cells with short operation time. The aim of this study was to compare the quality of CB cells separated by SCCF and HES by analyzing repopulation in NOD/SCID mice.

STUDY DESIGN AND METHODS

A total of 1 x 10(6) or 5 x 10(6) nucleated cells derived from SCCF- or HES-separated, cryopreserved, thawed, and washed CB were transplanted into NOD/SCID mice. Eight weeks after transplantation, bone marrow cells of the recipient mice were examined by flow cytometry and hematopoietic progenitor assay for the engraftment of human cells.

RESULTS

Mice given human CB cells, separated by SCCF, showed degrees of engraftment similar to those in mice given HES-separated CB cells. There was no significant difference in the lymphohematopoietic reconstitution pattern in the two groups of mice.

CONCLUSION

SCCF processing does not appear to reduce the number of repopulating cells in NOD/SCID mice or alter the number of HPCs. It is now shown that these cells can be captured by SCCF and removed, and that they will engraft.

Status of umbilical cord blood transplantation in the year 2001

Umbilical cord blood (UCB) transplantation is limited to small recipients because of the low haemopoietic cell dose. Children from ethnic minority groups may benefit most from cord blood transplantation. Cohort controlled retrospective data indicate that there is significantly less acute and chronic graft versus host disease associated with the transplantation of human major histocompatibility complex (HLA) identical sibling cord blood compared with HLA identical sibling marrow. Controlled data are not yet available to confirm this observation in unrelated donor cord blood transplantation. The difference in leukaemic relapse seen after cord blood compared with bone marrow transplantation is also unknown. Tentative recommendations for the use of umbilical cord blood for transplantation are as follows. Collection is indicated from healthy newborn siblings when urgent transplantation is required for an older child in a family. The haematologist responsible for the older child, with the approval of the family and the obstetric team, should contact the medical director of the nearest cord blood bank to discuss arrangements for the UCB to be collected and HLA typed. Antenatal blood sampling to HLA type the fetus is not recommended. Umbilical cord blood should be considered when allogeneic transplantation is the treatment of choice for a child who does not have an HLA identical sibling, or a well matched unrelated adult volunteer donor. The potential advantages and disadvantages of using an HLA haplotype matched peripheral blood stem cell family donor rather than an unrelated cord blood donation should be discussed. There are no comparative data available as yet. At present, UCB transplantation should only be considered if a suitably matched donation contains at least 2 x 10(7)/kg nucleated cells. Effectively, this means that most adults and larger children are not suitable recipients.

An international survey of unrelated umbilical cord blood banking

OBJECTIVES

To investigate operational and technical practices within the field of cord blood banking.

MATERIALS AND METHODS

Cord blood banks world-wide were invited to participate in a survey of collection, processing and testing. The survey covered a 12-month period up to August 1998.

RESULTS

Replies were received from 18 cord blood banks. Analysis of the survey responses demonstrated wide variations in many aspects of cord blood banking.

CONCLUSION

There is a need for standardization to ensure adoption of best practice.

Dextran sedimentation in a semi-closed system for the clinical banking of umbilical cord blood

BACKGROUND

The results of current processing procedures for reducing volume and recovering HPCs from umbilical cord blood (UCB) before cryopreservation vary.

STUDY DESIGN AND METHODS

Dextran was added to bags containing UCB, followed by sedimentation for 30 minutes. The processed UCB was then frozen. RBCs, nucleated cells, MNCs, CD34+ cells, CFUs and long-term culture-initiating cells (LTC-ICs), viability, and sterility were evaluated. Fractionations in ficoll-hypaque and hydroxyethyl starch (HES) were also run in parallel for comparison.

RESULTS

The nucleated cell (NC) recovery and RBC depletion were 86.1 percent and 94.3 percent, respectively (n = 50). Sedimentation with dextran also enabled the recovery of 80.7 percent MNCs and 82.6 percent CD34+ cells (n = 30). Postsedimentation samples displayed no impairment of CFU growth (n = 42, 108.7% CFU-C, 104.6% CFU-GEMM, 107% CFU-GM, and 95.7% BFU-E). Long-term cultures on five paired samples before and after sedimentation generated similar numbers of CFU-C each week (p = 0.88). Limiting dilution analysis of 12 paired pre/postsedimentation samples showed comparable median proportions of LTC-ICs (1/6494 vs. 1/5236; p = 0.18). The cell viability of 24 samples of thawed UCB after sedimentation was 90.3 percent (77.5-96%) and the recovery of CFU-C, CFU-GEMM, CFU-GM, and BFU-E of 11 postsedimentation samples was 93.4 percent, 84.9 percent, 92.3 percent, and 83.4 percent, respectively. NC recovery was significantly higher after treatment with dextran than with ficoll-hypaque (n = 30; 88.5% vs. 29.1%; p<0.005) and HES treatment (n = 21; 88.5% vs. 76.4%; p = 0.004). However, MNCs, CD34+ cells, CFUs, LTC-ICs, and RBCs were comparable. Two cycles of dextran sedimentation recovered 93.9 percent of NCs with cell viability of 98.6 percent (96.5-100%), whereas 11.7 percent of RBCs were retained (n = 20). The final yield volume was 33.5 (28-41) mL.

CONCLUSION

In a semi-closed system, dextran sedimentation enabled volume reduction of UCB without significant quantitative and qualitative losses of HPCs.

Stem cell collection filter system for human placental/umbilical cord blood processing

BACKGROUND AND OBJECTIVES

The hydroxyethyl starch method and the Top & Bottom method have been used worldwide for the volume reduction of human placental/umbilical cord blood (PCB) units. To simplify the preparation of nucleated cell (NC) concentrates, we developed a new filter device--the stem cell collection filter system (SCF SYSTEM)--which can collect mononuclear cells (MNC) at a high recovery rate.

MATERIALS AND METHODS

The SCF SYSTEM consisted of a filter and two bags. Multilayered polyethylene terephthalate non-wovens, coated with a hydrophilic polymer, were used as filter media. PCB units were filtered by gravity (n = 12). Red blood cells, platelets and plasma were drained into the drain bag, and the NC trapped on the filter media was collected in the recovery bag by reverse washing. Recovered cell fractions were evaluated.

RESULTS

The volume of cell concentrate recovered was 27.4 +/- 2.2 ml (mean +/- SD, n = 12). The whole time required for processing was less than 30 min, and handling was very simple. The viability of recovered NC was 97.8 +/- 3.2%. The recovery of lymphocytes, monocytes and granulocytes was 79.5 +/- 16.9%, 79.8 +/- 20.4% and 39.0 +/- 19.5%, respectively. The recovery rate of granulocytes was significantly lower than that of monocytes and lymphocytes (P < or = 0.0001). The recovery rates of CD3+ cells, CD19+ cells and CD56+ cells were almost the same as that of MNC. The recovery rates of CD34+ cells, total colony-forming cells and long-term culture-initiating cells were 81.7 +/- 27.0% (n = 11), 80.8 +/- 27.7% (n = 12) and 75.0 +/- 18.4% (n = 2), respectively.

CONCLUSION

The new filter system was shown to be efficient for PCB processing, encompassing a very simple handling procedure with a good recovery of haematopoietic progenitor cells. Hence, the SCF SYSTEM is potentially useful for the volume reduction of PCB units for cord blood banking.

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

BACKGROUND

In UC blood banking, volume and RBC reduction of the collected UC blood allows more efficient long-term storage and decreases infusion-related hemolysis and DMSO toxicity. However, high cell yields are imperative. At the St Louis Cord Blood Bank, we have systematically addressed processing/freezing and have developed a simple processing/freezing procedure.

METHOD

The methodology is a modification of the hetastarch sedimentation and volume reduction approach of Rubinstein at the New York Placental Blood Program. Cord blood is mixed with a 1:5 v/v ratio of hetastarch. The product is incubated for 45 min in an inverted position in a refrigerated centrifuge (4 degrees C), and then is spun for 5 min at 50 g. RBC concentrate is drained from the bottom. The volume drained is calculated to remove 80% of RBC. The UC blood unit is then resuspended and spun for 13 min at 420 g. Plasma is expressed from the top.

RESULTS

A final product volume of 27 mL (range 16-58 mL) was obtained from an original 50-200 mL of UC blood collected. The average yield of total nucleated cells pre- and post-processing was 90% for the first 4055 UC blood units banked. Pre- and post-processing CFU and CD34 yields were tested in a cohort and were similarly conserved. With a processing time of 3 h for a single cord, this process is time efficient and lends itself well to processing several units at the same time. The technique has been exported to other laboratories with similar yields.

DISCUSSION

This simple methodology results in reliable yields and is well suited to larger scale banking.

Collection, processing and cryopreservation of umbilical cord blood for unrelated transplantation

Umbilical cord blood (UCB) transplantation is being used as an alternative source of hematopoietic stem cells for bone marrow reconstitution. Separation and processing of UCB samples in large numbers for storage in cord blood banks ideally needs to be partially automated. The aim of this study was to establish and standardize a method for unrelated cord blood banking as well as the biological characterization of the samples. Up to October 1999, a total of 938 UCB units (mean volume 84.6 +/- 23.6 ml, nucleated cell (NC) count 0.90 +/- 0.37 x 109, total CFU-GM 79 +/- 72 x 104, CD34+ cell count 2.46 +/- 2.72 x 106) had been collected. Twenty-three per cent of all UCB samples had a NC count below 0.4 x 109 and were discarded. The initial bacterial contamination rate was reduced to less than 5% as a result of extensive training in collection procedures. Using a modification of a triple bag system and adding a solution of 6% hydroxyethyl starch, the UCB was separated by two centrifugation steps into three components: buffy coat, red cell and plasma fractions. The overall recoveries for NC, CFU-GM and CD34+ cells were 87.4 +/- 8.5%, 88.8 +/- 6.6% and 90.3 +/- 12.4%, respectively, in a mean final volume of 27 +/- 4.2 ml.

Cord blood banking: volume reduction using "Procord" Terumo filter

Cryopreserved cord blood (CB) banking, space storage, and ABO major incompatibility transfusion as well as potential progenitor cell loss during processing, are the subjects of this study. We evaluate processing of fresh and thawed CB on "Procord" (Terumo Corp., Japan). On 16 freshed CBs, mean NC, CD34, CFU-GM yields were, respectively, 54% (SD +/- 20), 75% (SD +/- 25), and 171% (SD +/- 168) in a final volume of 20 ml. Final product was enriched in mononuclear cells (mean 69% granulocytes depletion) with reproducible erythrocyte and platelet depletions means of 97% (SD +/- 1.5) and 93% (SD +/- 8). On seven previous whole frozen CB units, Procord gave comparable red blood cell (98%) depletion with 53% (SD +/- 30) mean CD34 recovery. Procord is an efficient method for erythrocyte depletion of CB, and recoveries of NC and progenitor cells are comparable to those obtained with similar processing. Nevertheless, as all existing methods, it is associated with cell and progenitor cell loss.