Umbilical cord blood banking for unrelated transplantation: evaluation of cell separation and storage methods

Therapeutic mesenchymal stromal stem cells: Isolation, characterization and role in equine regenerative medicine and metabolic disorders

Mesenchymal stromal cells (MSC) have become a popular treatment modality in equine orthopaedics. Regenerative therapies are especially interesting for pathologies like complicated tendinopathies of the distal limb, osteoarthritis, osteochondritis dissecans (OCD) and more recently metabolic disorders. Main sources for MSC harvesting in the horse are bone marrow, adipose tissue and umbilical cord blood. While the acquisition of umbilical cord blood is fairly easy and non-invasive, extraction of bone marrow and adipose tissue requires more invasive techniques. Characterization of the stem cells as a result of any isolation method, is also a crucial step for the confirmation of the cells' stemness properties; thus, three main characteristics must be fulfilled by these cells, namely: adherence, expression of a series of well-defined differentiation clusters as well as pluripotency. EVs, resulting from the paracrine action of MSCs, also play a key role in the therapeutic mechanisms mediated by stem cells; MSC-EVs are thus largely implicated in the regulation of proliferation, maturation, polarization and migration of various target cells. Evidence that EVs alone represent a complex network 0involving different soluble factors and could then reflect biophysical characteristics of parent cells has fuelled the importance of developing highly specific techniques for their isolation and analysis. All these aspects related to the functional and technical understanding of MSCs will be discussed and summarized in this review.

Single-step enrichment of basophils from human peripheral blood by a novel method using a Percoll density gradient

We have developed a novel continuous flow-through cell separation method using a Percoll density gradient. This method can continuously separate a large number of cells into five fractions according to their densities. To apply this method to the separation of basophils, Percoll density gradients were modified to improve basophil enrichment. When a set of Percoll density gradients was prepared (1.071, 1.075, 1.080, 1.084, and 1.090 g/mL) the basophils in a healthy volunteer were enriched by an average of 23.1 and 63.5% at Percoll densities of 1.075 (fraction 3) and 1.080 g/mL (fraction 4), respectively. On average, the yield of basophils was 1.66 × 10(5) cells in fraction 3 and 1.61 × 10(5) cells in fraction 4 from 9 mL of peripheral blood. The expression of CD203c (cluster of differentiation 203c) on separated basophils was upregulated by anti-immunoglobulin E stimulation similar to basophils in whole blood. Histamine release induced by calcium ionophore was also observed in the separated basophils. The present method will be useful for basophil enrichment since it preserves their function without using counterflow elutriation and immunological reagents, and this method will be effective as a preparative separation for cell purification by flow cytometry.

Umbilical Cord Blood Research: Current and Future Perspectives

Umbilical cord blood (UCB) banking has become a new obstetrical trend. It offers expectant parents a biological insurance policy that can be used in the event of a child or family member's life-threatening illness and puts patients in a position of control over their own treatment options. However, its graduation to conventional therapy in the clinical realm relies on breakthrough research that will prove its efficacy for a range of ailments. Expanding the multipotent cells found within the mononuclear fraction of UCB so that adequate dosing can be achieved, effectively expanding desired cells ex vivo, establishing its safety and limitations in HLA-mismatched recipients, defining its mechanisms of action, and proving its utility in a wide variety of both rare and common illnesses and diseases are a few of the challenges left to tackle. Nevertheless, the field is moving fast and new UCB-based therapies are on the horizon.

Recovery of CD45(-)/Lin(-)/SSEA-4(+) very small embryonic-like stem cells by cord blood bank standard operating procedures

BACKGROUND AIMS

Very small embryonic-like (VSEL) stem cells are a rare cell population present in bone marrow, cord blood and other tissues that displays a distinct small cell size and the ability to give rise to cells of the three germ layers. VSEL stem cells were reported to be discarded in the red blood cell fraction by Ficoll-Paque density gradient centrifugation during the processing of bone marrow and cord blood specimens. However, most cord blood banks do not include density gradient centrifugation in their procedures while red blood cells are removed by Hespan sedimentation following the Cord Blood Transplantation Study cord blood bank standard operating procedures (COBLT SOP). To clarify the retention of VSEL stem cells, we investigated the recovery of VSEL stem cells following COBLT SOP guidelines.

METHODS

The recovery of CD45(-)/Lin(-)/SSEA-4(+) VSEL stem cells of umbilical cord blood was examined by flow cytometry before and after COBLT SOP processing, and relative expression of pluripotent genes was analyzed by quantitative polymerase chain reaction.

RESULTS

CD45(-)/Lin(-)/SSEA-4(+) VSEL stem cells were mostly recovered in the final products following COBLT SOP guidelines. The expression of pluripotent genes could be maintained at >80% in products after hetastarch (Hespan; B. Braun Medical Inc., Irvine, CA, USA) processing.

CONCLUSIONS

The rare sub-population of CD45(-)/Lin(-)/SSEA-4(+) VSEL stem cells survived after Hespan sedimentation. This finding suggests that umbilical cord blood units cryopreserved by COBLT SOP in cord blood banks should retain most VSEL stem cells present in the un-processed specimens.

Methods of freezing cord blood hematopoietic stem cells

BACKGROUND

Cord blood (CB) is a valuable source of hematopoietic stem cells (HSCs). Extended storage of CB is possible provided that validated cryopreservation procedures are used. The study objective was to determine optimal methods of CB cryopreservation.

STUDY DESIGN AND METHODS

In the study we 1) compared the effect of two-step cryopreservation and controlled-rate freezing method on the postthaw quality of CB (Study A) and 2) evaluated the postthaw quality of HSC fractions isolated from CB with various methods and frozen with controlled-rate freezing method (Study B). The same cryoprotectant mixture was used for 20 CB units (Study A) and 122 CB units (Study B).

RESULTS

In Study A, 13.79 × 10(8) and 13.29 × 10(8) initial white blood cell (WBC) counts decreased to 6.38 × 10(8) and 6.02 × 10(8) after thaw for the two methods, respectively. The mononuclear cell (MNC) counts decreased from 5.90 × 10(8) to 3.71 × 10(8) and from 5.64 × 10(8) to 3.47 × 10(8) dependent on the method. MNC viability decreased from 99.0% to 97.4% for the former and from 98.5% to 97.2% for the latter method. The differences were insignificant. In Study B, postthaw WBC recovery in HSC fractions was 74.4% to 103.5%, MNC recovery 106.4% to 118.5%, CD34+ cell recovery 102.5% to 150.2%, and MNC viability 94.1% to 97.4%.

CONCLUSION

Neither the cryopreservation procedure nor the freezing of isolated HSCs affected product quality, which may indicate that various freezing methods can be used for cell banking provided the they follow recommendations of good manufacturing practice and Directive 2004/33/EC.

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.

A new seed-train expansion method for recombinant mammalian cell lines

A new approach has been developed and used to minimize the timeand more carefully monitor and control the seed-train expansionprocess of recombinant mammalian cell lines. The process uses 50or 100 ml cryo-bags that contain frozen cells at high cell densities of 20 x 10(6) ml(-1) (100 ml bags) or 40 x 10(6) cells ml(-1) (50 ml bags). The frozen bag cell suspension is thawed and transferred directly into a bioreactorthat has been modified such that pH, DO and temperature can becontrolled at the initial volume of two liters (the working volume eventually increases to 12 l). The successful use of thesecryo-bags and the modified ;inoculation' bioreactor to initiate anew seed train expansion of rBHK or rCHO cells is described herein. The interval between cell thawing and the accumulation ofsufficient cell mass to inoculate a production reactor is reducedby at least 25 to 30 days compared to the conventional method that begins with the thaw of 1-2 ml cryo-vials. This ;one-step'technology leads to a much more consistent scale-up by reducingmanual operations and avoiding subjective decisions during the scale-up phase. The cell metabolic rates and product integritywere similar to the control experiments. Furthermore, it was found that it is not necessary to include a wash step to removeDMSO prior to the inoculation.

Characterization of cell-banking parameters for the cryopreservation of mammalian cell lines in 100-mL cryobags

This article describes a cell banking process for rBHK cell lines in 100-mL cryobags. As the use of larger volume cell banks requires greater cell numbers and longer preparation time, extensive characterization of key process parameters beyond the conventional ranges was performed to support a cGMP banking process. All experiments were conducted using two recombinant BHK21 cell lines, one of them cotransfected with Hsp70. The results show that the entire cell banking process for these BHK cell lines can be performed at room temperature. A DMSO exposure time up to 5 h either directly in a bioreactor or in shaker flasks did not result in any significant negative effect after cell thaw, when the cryocontainers were frozen immediately after filling. Extensive characterization did not indicate any significant apoptotic effects after thaw. However, the Hsp70 cotransfected cell line did show a slightly better protection from potential cryopreservation-induced apoptosis. Surprisingly, it was found that cells transferred into cryobags showed a low recovery rate after thaw if the incubation time exceeded 1.5 h before freezing. Additional experiments confirmed that the DMSO exposure time inside the cryocontainer in contrast to the DMSO exposure in a reactor or shaker flasks is much more critical. The cryobag cell banking process should therefore be performed within a 1(1/2)-2 h window; a banking process for vials should not exceed 2(1/2) h.

Influence of obstetric factors on the yield of mononuclear cells, CD34+ cell count and volume of placental/umbilical cord blood

AIM

Placental/umbilical cord blood (CB) has been used increasingly not only for transplantations, but also in the field of life science research. However, little information is available on the biological characteristics of CB units collected in rural areas because no medical facilities are affiliated with CB banks. Little attention has been paid to the collection of CB units in rural areas compared to CB collected in metropolitan areas. CB is a precious source for life science research due to the recent low birth rate in Japan. Therefore, to efficiently utilize CB units, the purpose of the present study was to investigate the optimum obstetric factors associated with a higher yield of mononuclear/CD34(+) cells per CB unit.

METHODS

CB units were collected at a single hospital (Hirosaki National Hospital). A total of 126 CB units from 105 vaginal deliveries and 21 cesarean section deliveries were available for cell separation within 24 h. Mononuclear low-density (LD) cells were separated using Ficoll-Paque and then processed for CD34(+) cell enrichment using magnetic cell sorting. Associations between the maternal/neonatal factors and the yield of LD/CD34(+) cells were analyzed.

RESULTS

Despite the larger net weight of CB collected from cesarean section deliveries, the total number of LD cells collected from vaginal deliveries was significantly higher than that collected from cesarean section deliveries. The total number of LD cells per CB unit from primigravidae was significantly higher compared with that collected from from multigravidae.

CONCLUSION

CB units from vaginal deliveries of primigravidae may be more favorable because they contain a higher yield of mononuclear cells.

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.

Exposure of cord blood to Mycobacterium bovis BCG induces an innate response but not a T-cell cytokine response

Despite routine vaccination with Mycobacterium bovis bacillus Calmette-Guérin (BCG) soon after birth, tuberculosis in babies and adults remains epidemic in South Africa. The immune responses of the naïve newborn child and how they are affected by vaccination with BCG are as yet not fully understood. Immunity during pregnancy and in healthy human newborns may be skewed toward type 2 cytokine production; however, it is type 1 cytokines that are required for protection against M. tuberculosis infection. To better understand neonatal cytokine responses prior to and following exposure to mycobacteria, we have collected cord blood and peripheral blood samples and evaluated the cytokine response following ex vivo incubation with BCG. Gamma interferon (IFN-gamma), interleukin 10 (IL-10), IL-12, and low levels of IL-13 and IL-5 but no IL-4 were secreted into the culture supernatant of cord blood mononuclear cells. Intracellular staining showed that IL-10 and IL-12 were produced by monocytes and that IFN-gamma was produced by natural killer (NK) cells but not by CD4(+) or CD8(+) T cells. In contrast, in the peripheral blood samples collected from babies 13 weeks post-BCG vaccination, IFN-gamma was detected within CD4(+) and CD8(+) cells. Taken together, the data suggest a central role for Th1 cytokines in naïve as well as BCG-vaccinated neonates in the protective immune response to tuberculosis. NK cell-derived IFN-gamma produced in naïve neonates likely plays a key protective role via monocyte activation and the priming of a subsequent adaptive Th1 response.

Collection strategies and cryopreservation of umbilical cord blood

The aim of this study was to compare (a) two different umbilical cord blood (UCB) collection methods while the placenta is still in the uterus (in utero), and (b) to evaluate the efficacy of four cryopreservation protocols based on UCB haematopoiestic stem cell (HSC) recovery. We analysed UCB samples collected with our original collection system designed for active Syringe/Flush/Syringe method or by standard in utero method. For comparing different cryopreservation procedures, dimethyl sulphoxide (DMSO) at final concentration of 5 and 10% was used and combined with our own controlled-rate or uncontrolled-rate cryopreservation. A total of 99 samples were collected. A significantly higher UCB volume, total nucleated cell and mononuclear cell were seen following the first collection strategy (n= 49; mean +/- SD, 103 +/- 35.4 mL; 12.34 +/- 5.27 x 10(8); 595 +/- 3.47 x 10(6)) vs. the second strategy (n= 50; 86 +/- 29.3 mL; 9.87 +/- 4.47; 424 +/- 2.82 x 10(6)) respectively (P < 0.01). The discard rate was 14% for the first and 36% for the second collection strategy (P < 0.01). It was shown that the most efficient procedure was the controlled-rate protocol combined with lower (5%) DMSO concentration. Using active Syringe/Flush/Syringe method, we collected UCB with greater volumes and with lower discard rate compared to the standard by gravity technique. The data presented also showed much better recovery of UCB cells when controlled-rate freezing procedure and 5% DMSO were combined.

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.

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.

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.

Engraftment kinetics of human CD34+ cells from cord blood and mobilized peripheral blood co-transplanted into NOD/SCID mice

We have reported short periods of post transplant neutropenia in human patients co-transplanted with cord blood (CB) and low numbers of haploidentical mobilized peripheral blood (MPB) CD34+ cells. To investigate the effect that the proportion of MPB to CB cells may have on engraftment kinetics, we have co-transplanted fixed numbers of human CB CD34+ cells mixed with different numbers of MPB CD34+ cells into NOD/SCID mice. We periodically quantified the proportion of human cells and the relative contribution of MPB and CB cells to the human engraftment on marrow aspirates. At the lowest MPB/CB ratios (5 : 1, 10 : 1), the contribution of CB cells predominated at all time points analyzed, and in three out of four experiments MPB cell contributions progressively decreased from day +15. At higher MPB/CB ratios, MPB cells had a more important contribution to both early and late engraftment, with the highest cell ratio resulting in only marginal CB cell engraftment. Therefore, our results showed greater potential, on a per cell basis, of human CB vs MPB cells for competitive sustained engraftment in the xenogeneic model used, which was only abrogated by the co-infusion of very high numbers of MPB cells.

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.

Cord blood transplantation in adult patients

Early clinical reports outlining outcomes for primarily pediatric patients undergoing UCB transplantation point to delayed time to hematopoietic recovery and favorable incidence and severity of GvHD. Recently, clinical reports in adult patients identified the feasibility of UCB transplantation for those patients lacking an available histocompatible-related or unrelated adult donor Intensive clinical and laboratory research is ongoing focused on strategies to foster UCB allogeneic donor engraftment thereby allowing wider application of this stem cell source for patients requiring allogeneic transplantation.

A new automated cell washer device for thawed cord blood units

BACKGROUND

The current available techniques to wash out DMSO from thawed umbilical cord blood (UCB) units are based essentially on standard centrifugation in an open system with various degrees of cell loss.

STUDY DESIGN AND METHODS

We evaluated the capacity of a new automated closed device (Cytomate, Baxter, IL) to wash out the DMSO from thawed UCB units, saving at the same time the progenitor and accessory cells in terms of CD34+ cells and MNCs. We modified the standard software of the device and calculated the cell recovery on 25 UCB units. Moreover, we set up a new gas chromatographic method to exactly detect the DMSO removal rate.

RESULTS

To evaluate the efficiency of the Cytomate device, we considered the postthawing (prewashing) versus postwashing cell recovery. The average recovery (%) in terms of total nucleated cells was 63.30 (range, 40.12-89.00), CD34+ cells was 70.20 (range, 11.51-89.01), CD3+ cells was 61.01 (range, 28.80-87.08), CD4+ cells was 62.53 (range, 30.62-96.73), CD8+ cells was 57.4 (range, 26.87-94.72), CD19+ cells was 63.33 (range, 39.10-90.33), CD16+/56+ cells was 70.67 (range, 8.91-98.40), CFU-GM was 74.33 (range, 20.23-98.60), total CFUs was 82.34 (range, 14.83-247.12), and viability was 89.67(range, 70.74-98.30). The total working time required was, on average, 15 minutes (range, 7-20).

CONCLUSIONS

The Cytomate device demonstrated a satisfying efficiency in cell recovery and in maintaining the clonogenic power of the UCB graft. The removal rate of DMSO was practically complete with evident advantages for the recipient. Finally, the entire manipulation performed in a closed system revealed to be safe, maintaining the sterility of the graft.

Preferential expression of the vasoactive intestinal peptide (VIP) receptor VPAC1 in human cord blood-derived CD34+CD38- cells: possible role of VIP as a growth-promoting factor for hematopoietic stem/progenitor cells

Primitive hematopoietic progenitor cells such as severe combined immunodeficiency- repopulating cells and long-term culture-initiating cells are enriched in CD34+CD38- cells derived from various stem cell sources. In this study, to elucidate the features of such primitive cells at the molecular level, we tried to isolate genes that were preferentially expressed in umbilical cord blood (CB)-derived CD34+CD38- cells by subtractive hybridization. The gene for VPAC1 receptor, a receptor for the neuropeptide vasoactive intestinal peptide (VIP), was thereby isolated and it was shown that this gene was expressed in both CD34+CD38- and CD34+CD38+ CB cells and that the expression levels were higher in CD34+CD38- CB cells. Next, we assessed the effects of VIP on the proliferation of CD34+ CB cells using in vitro culture systems. In serum-free single-cell suspension culture, VIP enhanced clonal growth of CD34+ CB cells in synergy with FLT3 ligand (FL), stem cell factor (SCF), and thrombopoietin (TPO). In serum-free clonogenic assays, VIP promoted myeloid (colony-forming unit-granulocyte/macrophage (CFU-GM)) and mixed (CFU-Mix) colony formations. Furthermore, in Dexter-type long-term cultures, VIP increased colony-forming cells at week 5 of culture. These results suggest that VIP functions as a growth-promoting factor of CB-derived hematopoetic progenitor cells.

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.

Cord blood processing with an automated and functionally closed system

BACKGROUND

Umbilical cord blood processing with standard centrifugation techniques is performed in open systems and results in varying cell and volume recoveries.

STUDY DESIGN AND METHODS

Forty umbilical cord blood donations were randomly assigned to processing either with a microprocessor-controlled cell separator equipped with closed disposables or with a manual separation procedure in blood bags. The collection efficiency of nucleated cells, MNCs, RBCs, and CD34+ cells and the processing time were analyzed.

RESULTS

Using the cell processor, mean collection efficiencies were 78.6 +/- 24.9 percent for nucleated cells, 77.4 +/- 27.8 percent for MNCs, 55.5 +/- 14.6 percent for RBCs, and 83.6 +/- 32.5 percent for CD34+ cells, while they were 73.1 +/- 13.2 percent for nucleated cells, 78.1 +/- 14.9 percent for MNCs, 26.0 +/- 12.2 percent for RBCs, and 77.0 +/- 17.6 percent for CD34+ cells when using the standard centrifugation technique. The processing time was about 20 minutes for automated processing and 60 to 80 minutes for the standard centrifugation technique.

CONCLUSION

Using the new cell processor, the collection efficiencies for nucleated cells, MNCs, and CD34+ cells are similar to those obtained by established centrifugation techniques while the RBC reduction is less effective. The main advantages of the new systems are the closed system, the more standardized processing procedure, and a significantly shorter processing time.

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.

Ex vivo expansion of megakaryocyte progenitors from cryopreserved umbilical cord blood. A potential source of megakaryocytes for transplantation

OBJECTIVE

Umbilical cord blood (CB) provides an alternative source of hematopoietic progenitor cells for transplantation; however, prolonged thrombocytopenia remains a major obstacle due to the low numbers of megakaryocyte progenitor (Mk-prog) cells and their subsequent delayed engraftment. In this study, we improved techniques for enrichment, cryopreservation, and ex vivo expansion of Mk-prog cells from CB.

MATERIALS AND METHODS

CB mononuclear cells (MNC) were isolated and Mk-prog enriched by sedimentation on gelatin followed by centrifugation with Ficoll-Hypaque and cryopreserved. The capacity of MNC to produce Mk-prog cells, assessment of CD34(+) and Mk-prog expansion in liquid culture, and analysis of the cell populations by flow cytometry were studied in cryopreserved separated CB and compared to whole CB and freshly separated samples.

RESULTS

Excellent viability of greater than 85% was maintained after cryopreservation of separated CB. The number of colony-forming Mk-prog, myeloid, and erythroid progenitor cells did not decrease with cryopreservation. Flow cytometric analysis of cryopreserved cells revealed significant removal of the residual red blood cells while maintaining complete recovery of CD34(+), CD41(+) (Mk), myeloid, and T and B cells compared to noncryopreserved CB cells. There was no difference in the ability of separated cryopreserved MNC CB cells to be expanded in short-term liquid cultures.

CONCLUSIONS

The conditions defined here for cryopreservation of gelatin/Ficoll-Hypaque separated CB, followed by ex vivo expansion of MNC, allowed complete recovery of proliferating CD41(+), CD34(+), Mk-prog cells, and other hematopoietic progenitors. Mk-prog cell expansion just before the scheduled transplantation is easily applicable by this technically simple and economical procedure that requires only an aliquot of red cell cell-depleted MNC to be separated from the CB unit before cryopreservation.

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.

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.

Umbilical cord blood progeny cells that retain a CD34+ phenotype after ex vivo expansion have less engraftment potential than unexpanded CD34+ cells

BACKGROUND

Because of the limitation of cell numbers associated with cord blood harvests, there is a need to determine the efficacy of using ex vivo-expanded cord blood cells in a transplantation setting. In this study, limiting-dilution analysis was used in nonobese diabetic mice with severe combined immunodeficiency (NOD/SCID) to compare the engraftment potential of progeny cells expressing the CD34+ phenotype after expansion with that of uncultured CD34+ cells.

STUDY DESIGN AND METHODS

Cord blood CD34+ cells were cultured in Iscove's modified Dulbecco medium supplemented with 10-percent fetal calf serum (FCS) and IL-6, SCF, megakaryocyte growth and development factor, and Flt3 ligand. The resulting ex vivo-expanded products were assessed for total numbers of nucleated cells, CD34+ cells, and CFUs and long-term culture-initiating cell activity. The engraftment potentials of cultured progeny CD34+ cells and uncultured CD34+ cells were determined by using NOD/SCID mice.

RESULTS

After 14 days of culture, total nucleated cell counts increased over input values by 180 +/- 59-fold, CD34+ cell numbers by 44 +/- 13-fold, CFU activity by 23 +/- 5-fold, and long-term culture-initiating cell activity by 20 +/- 6-fold (mean +/- SD; n = 6). The frequency of SCID-repopulating cells (SRC) in mice transplanted with uncultured products was 1 per 20,000 CD34+ cells (95% CI, 1:10,000-1:38,000) and that in mice receiving ex vivo-expanded products was 1 per 418,000 progeny CD34+ cells (95% CI, 1:158,000-1:1,100,000). Taken together, these data indicated that, after 2 weeks of culture, there was a modest twofold increase in the total number of SRCs. However, the levels of human CD45 cell engraftment in NOD/SCID recipients of progeny CD34+ cells were significantly lower than those in mice receiving equivalent numbers of uncultured CD34+ cells (p<0.05).

CONCLUSION

Umbilical cord blood progeny cells retaining a CD34+ phenotype after ex vivo expansion have less engraftment potential than do unexpanded CD34+ cells.

Umbilical cord blood for allogeneic transplantation in children and adults

Early clinical reports outlining outcomes for primarily pediatric patients undergoing UCB transplantation, point to delayed time to hematopoietic recovery, and favorable incidence and severity of graft-versus-host disease. Intensive clinical and laboratory research is ongoing focused on strategies to foster UCB allogeneic donor engraftment, thereby allowing wider application of this stem cell source for patients requiring allogeneic transplantation.

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.

Low numbers of megakaryocyte progenitors in grafts of cord blood cells may result in delayed platelet recovery after cord blood cell transplant

Delayed platelet recovery is an inherent problem with cord blood cell transplantation (CBCT). To investigate this problem, the number of human megakaryocyte (MK) progenitor cells in cord blood (CB; n = 24) was measured and compared with that in G-CSF-mobilized peripheral blood stem cells (PBSC; n = 25). The median numbers of colony-forming units for MK (CFU-MK) that were detected by a serum-free assay system in CB and peripheral blood (PB) were 26 (range, 6-102)/10(5) nucleated cells (NC) and 37 (2-540)/10(5) mononuclear cells (MNC), respectively. The numbers of colony-forming units for granulocyte/macrophage (CFU-GM) were 88 (33-241)/10(5) NC in CB and 138 (6.3-1,250)/10(5) MNC in PB. The frequencies of CD34(+) cells in CB and PB were, respectively, 0.44% (0.10-1.07) and 0.98% (0.05-20.8). The numbers of CFU-MK in CB and PBSC were correlated with those of CD34(+) cells. The estimated number of infused CFU-MK in CBCT was 1/15 that of PBSC transplantation (PBSCT), based upon the above data and the widely used standard doses for both types of transplants. Further, the numbers of infused CFU-MK in patients who received allogeneic PBSCT at our institute were inversely correlated with the speed of platelet recovery. These data indicate that delayed platelet recovery after CBCT is simply due to the low number of CFU-MK contained in grafts.

Human umbilical cord blood banking and transplantation: a state of the art

Human umbilical cord blood has proven to be a feasible alternative source of hematopoietic stem cells for pediatric and some adult patients with major hematologic disorders. This has promoted the establishment of cord blood banks for use in unrelated transplants worldwide. The banking of umbilical cord blood offers many advantages: absence of donor risk, absence of donor attrition, immediate availability, and the ability to expand available donor pools in targeted ethnic and racial minorities currently underrepresented in all bone marrow registries. Preliminary clinical experience suggests that, due to the immunological immaturity of cord blood cells, graft versus host disease might be lower than when using bone marrow from adult donors and HLA restrictions might be less stringent. Techniques to improve the efficacy of blood banks are currently under investigation. Closed cord blood collection methods have proven to be superior to open in reducing the risk of microbial contamination. Efficient banking requires volume reduction of cord blood units without significant loss of progenitor cells, in order to decrease storage space and cost, and this may be achieved by using the separation techniques. Cryopreservation and thawing techniques have been established and do not seem to affect the viability and progenitor cell recovery or the feasibility of CD34(+) selection and ex vivo expansion. Nevertheless, many scientific, ethical, and social questions have arisen in connection with cord blood banking that need to be addressed.

Umbilical cord blood processing with the Optipress II blood extractor

BACKGROUND

We have previously shown that UC blood (UCB) units can be volume-reduced manually, in a closed system, without major losses of nucleated and CD34(+) cells and without the addition of exogenous material. Our aim was to use an automated method for the separation of the UCB components using the Optipress II, extractor, with the 'buffy-coat' collection in a standardized volume.

METHODS

After centrifugation, the 51 UCB units were separated into the three blood components, plasma, buffy coat (BC) and red cells, using the Optipress II. The final volume of the BC fraction, rich in nucleated and progenitor CD34(+) cells, was set at 30 mL. The nucleated and CD34(+) cell content of the UCB collections and the resulting BC were evaluated.

RESULTS

The UCB units were grouped according to the volume collected: Group I < 80 mL and Group II > or = 80 mL. Standardization of the BC at 30 mL resulted in significant volume reduction for both groups, with median values of 51% in Group I and 70% in Group II. The nucleated and CD34(+) cell recoveries in the BC from Group I were 88% and 99% respectively; for Group II they were 80% and 97%.

DISCUSSION

This semi-automated method of volume reduction efficiently reduces low, as well as high volume UCB units, with good nucleated- and progenitor-cell yields. Being a closed system and free of external material, the risk of contamination is minimized. The resulting fractions are then available for validation studies of the unit, effectively fulfilling the main requisites for UCB banking.