Maternal, neonatal and collection factors influencing the haematopoietic content of cord blood units

BACKGROUND AND OBJECTIVES: Umbilical cord blood (UCB) contains haematopoietic stem cells and can be used as an alternative to bone marrow transplantation in certain cases. Engraftment was dependent upon the haematopoietic progenitor cell content of the cord blood units. This study was designed to investigate the influence of obstetric, neonatal and collection factors on the volume and haematopoietic content of UCB donations. MATERIAL AND METHODS: A retrospective analysis of obstetric and neonatal factors was performed from 300 cord blood donations in Valencia Cord Blood Bank. Maternal, neonatal and collection factors influencing cord blood quality measured as volume, total nucleated cell count, CD34+ cells and colony-forming units (CFU) were analysed. RESULTS: Bigger babies produced cord blood units with larger volume, higher cells counts, CFU and CD34 cell counts. In the multivariate analysis, we found that both placental weight and mode of collection were predictor variables for total nucleated cell count, CD34 cells and CFU. CONCLUSION: Our study concludes that cord blood units must be collected before placental delivery and that birth weight, as an estimation of the placental weight, could be added to standard cord blood donors criteria in order to improve the bank efficiency.     

Optimizing donor selection in a cord blood bank

OBJECTIVES: The main limitation factor for the wide use of umbilical cord blood (UCB) as a source of hematopoietic progenitor for transplantation is cell dose. One of the specific areas identified by some studies for improvement of UCB collection is donor selection. METHODS: Over a 3-mth period, 391 consecutive maternal-neonatal pairs were evaluated during the pre-partum period in the maternity ward at La Fe University Hospital (Valencia) by the Cord Blood Bank staff. Reasons for discarding umbilical cord blood donors and collected UCB units at the Cord Blood Bank in Valencia have been analysed. Obstetric factors influencing TNC content of 1300 collected UCB units have been determined, in order to establish obstetric criteria for cord blood donors selection in our geographic area. RESULTS: Only 32.5% of potential cord blood donors were refused. Among 1300 UCB collected, 506 (38.9%) were discarded before cryopreservation, mainly due to low cell counts. Multivariate analyses showed that the main significant factors influencing nucleated cell count were the weight of the placenta, sex of newborn and mode of collection. CONCLUSIONS: Our study shows that maternal medical histories must be completely reviewed by medical staff before collection of the UCB. Obstetrical factors influence cell content of UCB and could be added to standard cord blood donor criteria in order to improve the bank efficiency.     

Experiences of the Dresdner Cord Blood Bank, supported by the Deutsche Knochenmarkspenderdatei

Allogeneic bone marrow and peripheral blood stem cell transplantation is the treatment of choice for some malignant hematologic diseases, marrow failure syndromes, and severe congenital immunodeficiency states. Since Gluckman et al reported in 1988 the first successful human leukocyte antigen (HLA)-matched sibling umbilical cord blood stem cell transplantation, it has been known that cord blood is a valuable source of hematopoietic stem cells. The Cord Blood Bank at the University Hospital of Dresden was founded in 1997 and started collecting, processing, and cryoconserving umbilical cord blood in August 1997. The cord blood bank is supported by the largest German donor registry: Deutsche Knochenmarkspenderdatei (DKMS) in Tubingen, Germany. With the informed consent of the mothers, the collection is performed in collaboration with six hospitals in Dresden, Berlin, and Bautzen. We routinely perform a volume reduction by centrifuging the blood bag and expressing the leukocyte-rich supernatant. Routinely, sterility, total nucleated cells (TNC), CD34+ cell count, HLA class I and II, ABO/Rh blood group, and colony-forming units are evaluated. The maternal blood is screened for anti-immunodeficiency virus (anti-HIV), anti-hepatitis C virus (anti-HCV), anti-hepatitis B surface antigen (HBsAg), anti-hepatitis B surface (anti-HBs), anti-hepatitis B core (anti-HBc), anticytomegalovirus (anti-CMV), and toxoplasmosis and with Treponema pallidum hemagglutination assay (TPHA). More than 1,000 cord blood units could be collected. Because of the required volume and cell count and because of sterility, 50% of the collected units had to be discharged. Our results are comparable with data of other cord blood banks: mean volume 79 mL; cell count after volume reduction-TNC, 7.16 x 10(8); mononucleated cells (MNC), 3.75 x 10(8); CD34+ cells, 1.95 x 10(6); colony-forming units (CFU), 67.1 x 10(4). To increase the pool of potential umbilical cord blood units and in order to evaluate the possibility for unrelated transplants, cryopreservation and banking of large numbers of cord bloods are necessary.     

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.     

Low usage rate of banked sibling cord blood units in hematopoietic stem cell transplantation for children with hematological malignancies: implications for directed cord blood banking policies

Directed sibling cord blood banking is indicated in women delivering healthy babies who already have a sibling with a disease that is potentially treatable with an allogeneic cord blood transplant. We evaluated the effectiveness of a national directed cord blood banking program in sibling HLA-identical stem cell transplantation for hematological malignancies and the factors influencing the usage rate of the stored cord blood units. Fifty families were enrolled from which, 48 cord blood units were successfully collected and 2 collections failed due to damaged cord/placenta at delivery. Among enrolled families 4 children needed transplantation; however, only one was successfully transplanted using the collected cord blood unit containing 2×10(7) nucleated cells/kg in conjunction with a small volume of bone marrow from the same HLA-identical donor. Two children received grafts from matched unrelated donors because their sibling cord blood was HLA-haploidentical, while the fourth one received bone marrow from his HLA-identical brother, since cord blood could not be collected due to damaged cord/placenta at delivery. With a median follow-up of 6 years (range, 2-12) for the 9 remaining HLA-matched cord blood units, none from the prospective recipients needed transplantation. The low utilization rate of sibling cord blood in the setting of hematopoietic stem cell transplantation for pediatric hematological malignant diseases necessitates the development of directed cord blood banking programs that limit long-term storage for banked cord blood units with low probability of usage such as non-HLA-identical or identical to patients who are in long-term complete remission.     

Cord blood banking: a historical perspective

Umbilical cord blood (UCB) contains stem and progenitor cells capable of restoring haematopoietic and immunological function in vivo . UCB is currently used as an alternative source of haematopoietic stem cells for transplantation in patients suffering from haematological malignancies, bone marrow failures and inherited metabolic disorders. In order to facilitate transplantation, large repositories of frozen cord blood units (CBUs) from altruistic donations have been established in many parts of the world and to date there are more than 300 000 units stored worldwide. These products have been banked under stringent quality conditions, in order to ensure their safety and efficacy.
The development and evolution of the policies and procedures currently in use in cord blood banking have been largely influenced by the clinical results of cord blood transplantation. This review aims to provide a historical overview of the various developments in the field of cord blood banking from its inception, highlighting the relevant aspects in their collection, banking and release that are known to influence the clinical outcome of these transplants.     

Comprehensive banking of sibling donor cord blood for children with malignant and nonmalignant disease

Banking of cord blood (CB) for unrelated hematopoietic stem cell (HSC) transplantation is well established. However, directed-donor banking of CB for siblings in a current good tissue practices (cGTP) environment has not previously been investigated. Families were eligible for the present study if they were caring for a child with a disorder treatable by HSC transplantation and expecting the birth of a full sibling. We devised standard operating procedures and policies to address eligibility, donor recruitment, donor and recipient evaluation, CB collection, shipping, graft characterization, storage, and release of CB from quarantine. Many of these policies are distinctly different from those established for unrelated-donor CB banks. We enrolled 540 families from 42 states. Collections occurred at several hundred different hospitals. No family was deferred on the basis of health history or infectious disease testing, but departures from standard donor suitability criteria were documented. Disease categories for sibling recipients included malignancy, sickle cell anemia, thalassemia major, nonmalignant hematological conditions, and metabolic errors. Mean CB volume (including anticoagulant) was 103.1 mL; mean nucleated cell count was 8.9 x 10(8). Cell dose exceeded 1.5 x 10(7) nucleated cells per kilogram for 90% of banked units. Seventeen units (3.4%) have been transplanted. Sixteen of the 17 CB allograft recipients had stable engraftment of donor cells. Remote-site collection of sibling donor CB can be accomplished with a high success rate and in a cGTP-guided environment. The cellular products have been used successfully for transplantation; their number and characteristics should be adequate to support the first prospective clinical investigations of sibling CB transplantation.     

Comparison of marrow and blood cell yields from the same donors in a double-blind, randomized study of allogeneic marrow vs blood stem cell transplantation

Forty healthy adult donors underwent marrow (BM) as well as peripheral blood (PBSC) stem cell collections for their HLA-identical adult siblings with hematologic malignancies. BM was harvested on day 1 (target 3 x 108 nucleated cells/kg, 10 microg/kg lenograstim (glycosylated G-CSF) administered on days 2-6, and a single leukapheresis performed on day 6. The blood volume processed was the higher of 200% donor blood volume or 10 liters. The total nucleated cell (TNC) yields from PBSC were 1.1- to 4.3-fold higher than BM (median 7.0 vs 3.1 x 10(8)/kg, P < 0.0001). Although BM contained a higher proportion of CD34+cells (1.3% vs 0.7%, P < 0. 0001) and a comparable proportion of CD3+ cells (median 29% vs 26%, P = 0.4), the absolute numbers of CD34+ and CD3+ cells and their subsets were several times higher in PBSC. There was a poor correlation between BM and PBSC CD34 and TNC numbers, but a significant correlation between BM and PBSC CD3 numbers. Only five of 40 BM harvests contained >/=2 x 10(6) CD34+ cells/kg compared with 35 of 40 PBSC harvests (P < 0.0001). We conclude that the numbers of progenitor and immunocompetent cells in PBSC are several times higher than in BM. It is possible to collect adequate numbers of progenitor cells from blood after lenograstim stimulation more frequently than from marrow, and donors yielding low quantities of progenitor cells from BM usually deliver better quantities from PBSC. Bone Marrow Transplantation (2000) 25, 501-505.     

Prospective study of one- vs two-unit umbilical cord blood transplantation following reduced intensity conditioning in adults with hematological malignancies

As the threshold nucleated cell dose for one-unit umbilical cord blood (UCB) in adults has not to date been firmly established, we prospectively compared one- vs two-unit UCB transplantation after reduced intensity conditioning (RIC) in adult patients with hematological malignancies. Study design specified one-UCB unit if the cryopreserved total nucleated cell (TNC) dose was 2.5 × 10(7)/kg recipient weight, otherwise two units matched at minima of 4/6 HLA loci to the patient and 3/6 to each other were infused. A total of 27 patients received one unit; 23 patients received two units. Median time to ANC >500/μL was 24 days (95% confidence interval 22-28 days), 25 days for one unit and 23 days for two units (P=0.99). At day 100, ANC >500/μL was 88.4 and 91.3% in the one- and two-unit groups (P=0.99), respectively. Three-year EFS was 28.6% and 39.1% in the one- and two-unit groups (P=0.71), respectively. Infusion of two units was associated with a significantly lower relapse risk, 30.4% vs 59.3% (P=0.045). Infused cell doses (TNC, CD3(+), CD34(+) and CD56(+)CD3(neg)) did not impact on engraftment, OS or EFS. Taken together, one-unit UCB transplantation with a threshold cell dose 2.5 × 10(7)/kg recipient weight after RIC is a viable option for adults, although infusion of two units confers a lower relapse incidence.     

Superior ex vivo cord blood expansion following co-culture with bone marrow-derived mesenchymal stem cells

One factor limiting the therapeutic efficacy of cord blood (CB) hematopoietic progenitor cell (HPC) transplantation is the low cell dose of the graft. This is associated with an increased incidence of delayed or failed engraftment. Cell dose can be increased and the efficacy of CB transplantation potentially improved, by ex vivo CB expansion before transplantation. Two ex vivo CB expansion techniques were compared: (1) CD133+ selection followed by ex vivo liquid culture and (2) co-culture of unmanipulated CB with bone-marrow-derived mesenchymal stem cells (MSCs). Ex vivo culture was performed in medium supplemented with granulocyte colony-stimulating factor, stem cell factor and either thrombopoietin or megakaryocyte growth and differentiation factor. Expansion was followed by measuring total nucleated cell (TNC), CD133+ and CD34+ cell, colony-forming unit and cobblestone area-forming cell output. When compared to liquid culture, CB-MSC co-culture (i) required less cell manipulation resulting in less initial HPC loss and (ii) markedly improved TNC and HPC output. CB-MSC co-culture therefore holds promise for improving engraftment kinetics in CB transplant recipients.     

Analysis for the optimal blood draw speed to collect sufficient peripheral blood mononuclear cells by COBE Spectra

In recent years the procedures for peripheral blood mononuclear cell (PBMNC) harvests have gradually been increasing. These PBMNCs are collected for several treatments, for example, donor lymphocyte infusion (DLI), immunotherapy for solid carcinoma, and regeneration therapy for ischemic limbs. In order to analyze the optimal procedure for collecting PBMNCs safely and efficiently, we evaluated 129 PBMNC apheresis procedures from April 1996 to May 2003, without hemopoietic stem cell mobilization by G-CSF. In every case, PBMNC collections were performed with a COBE Spectra cell separator (Gambro BCT). The median apheresis volume was 5550 mL. The median of blood draw speed was 48.1 mL/min. The median TNC (total nuclear cell) number in products was 50.4 x 10(3)/ micro L. In the regression analysis, no significant correlation was seen between the blood draw speed and the concentrations of TNC in products (Y = aX + b, a = 0.842497, b = 17.11352, r = 0.222032, P = 0.012464). A positive correlation was seen between WBC on apheresis day and the concentrations of TNC (Y = aX + b, a = 0.009822, b = 3.224679, r = 0.550431, P = 2.93 x 10(-11)). A significantly higher correlation was seen between the MNC (mononuclear cells) on apheresis day and the concentrations of TNC (Y = aX + b, a = 0.028278, b = 13.09266, r = 0.696988, P = 9.486 x 10(-9)). This study has shown evidence that a higher increment of blood draw speed does not provide a higher concentration of products. An adequate apheresis speed is about 40 mL/min. If we want to obtain sufficient cell counts, it is very important to obtain sufficient volume with a moderate blood draw speed, therefore protecting against side-effects.     

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.     

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.     

Posttransplantation Engraftment and Safety of Cord Blood Transplantation with Grafts Containing Relatively Low Cell Doses in Adults

The cell dose of a graft is a critical determinant of hematopoietic recovery and survival following unrelated cord blood transplantation. Most studies have found that the minimum acceptable nucleated cell dose should be between 1.5 X 10(7) and 2.0 X 10(7) nucleated cells per kilogram of body weight to reduce the time to myeloid recovery and increase the probability of engraftment. For some patients who have indications for hematopoietic cell transplants and for whom no other graft source except cord blood is available, it is difficult to decide whether they can receive cord blood grafts containing lower cell doses. In our study, patients who received cord blood grafts containing 1.0 X 10(7) to 2.0 X 10(7) cells/kg (n = 7) exhibited slower neutrophil and platelet recoveries compared with patients who received grafts containing total nucleated cell doses of 2.0 X 10(7) cells/kg and above (n = 93); however, 4 of those low-cell-dose recipients survived with a longer follow-up. Based on these preliminary results, cord blood grafts containing less than 2.0 X 10(7) cells/kg may be useful for cases where no grafts with higher cell doses or other stem cell sources are available.     

Directed sibling donor cord blood banking for children with β-thalassemia major in Greece: Usage rate and outcome of transplantation for HLA-matched units

Several cord blood banks store cord blood units from healthy siblings of patients, who are candidates for stem cell transplantation. We analyzed the quality characteristics of 50 cord blood units collected from families with β-thalassemia major and the outcome of subsequent stem cell transplantations during a 15-year period. All cord blood units were found suitable for banking based on a minimum net volume of 40 ml. The mean volume of the units was 98.9 ml; the mean total nucleated cell count (NC) was 7.8 × 10⁸ and the mean CD34⁺ cell count was 2.8 × 10⁶. Eight out of twelve HLA matched collections were released for transplantation. All but one recipient belonged to Pesaro II-III risk classes. Three patients received a cord blood graft with > 5 × 10⁷ NC/kg . One of them with Pesaro class I disease engrafted, whereas the other two who failed to engraft, were re-transplanted with bone marrow from the same donor later. Cord blood grafts containing NCs < 4 × 10⁷/kg combined with reduced volume bone marrow from the same donor were used in all 5 remaining cases and stable engraftment was achieved. All patients survived, 7/8 thalassemia-free. Cord blood banking from healthy siblings of children with β-thalassemia major can result in a successful transplantation in cases in which there is HLA compatibility. However, in high-risk patients, the use of combined cord blood and bone marrow grafts seems necessary in order to ensure stable engraftment, especially when cord blood unit cell counts are low.     

Washing of cord blood grafts after thawing: high cell recovery using an automated and closed system

BACKGROUND AND OBJECTIVES: Cord blood (CB) progenitor cells are an alternative source of haematopoietic stem cells for bone marrow reconstitution. The critical importance of cell dose in the clinical outcome has motivated the need to develop techniques aimed at reducing cell losses and increasing reproducibility. This aim of this study was to evaluate an automated CB washing protocol of thawed cord blood units using the Sepax device. MATERIALS AND METHODS: After an initial 1:1 dilution using a dextran/albumin-containing buffer, the cells were washed in order to obtain a final product ready for transplantation. The automatic method was compared with the conventional manual washing procedure. Blood samples were taken after thawing and after washing. The processing time, viability and mean recovery of nucleated cells (TNC) and progenitors were determined. RESULTS: The automatic procedure resulted in a median recovery of 93% CD34+ cells and 89% TNC; no significant differences were observed between methods. In addition, median viability, as assessed by annexin V and 7-aminoactinomycin D (7-AAD), was 98% and 94%, respectively, within CD34+ cells. CONCLUSIONS: The automatic washing method described is as effective as the manual method in terms of viability and progenitor cells recovery, but faster and easier for the operators to perform. Overall, our data suggest that the automatic method is safe and suitable for the routine washing of thawed CB grafts in the clinic.     

Results of the Cord Blood Transplantation Study (COBLT): clinical outcomes of unrelated donor umbilical cord blood transplantation in pediatric patients with hematologic malignancies

Outcomes of unrelated donor cord blood transplantation in 191 hematologic malignancy children (median age, 7.7 years; median weight, 25.9 kg) enrolled between 1999 and 2003 were studied (median follow-up, 27.4 months) in a prospective phase 2 multicenter trial. Human leukocyte antigen (HLA) matching at enrollment was 6/6 (n = 17), 5/6 (n = 58), 4/6 (n = 111), or 3/6 (n = 5) by low-resolution HLA-A, -B, and high-resolution (HR) DRB1. Retrospectively, 179 pairs were HLA typed by HR. The median precryopreservation total nucleated cell (TNC) dose was 5.1 x 10(7) TNC/kg (range, 1.5-23.7) with 3.9 x 10(7) TNC/kg (range, 0.8-22.8) infused. The median time to engraftment (absolute neutrophil count > 500/mm(3) and platelets 50 000/muL) was 27 and 174 days. The cumulative incidence of neutrophil engraftment by day 42 was 79.9% (95% confidence interval [CI], 75.1%-85.2%); acute grades III/IV GVHD by day 100 was 19.5% (95% CI, 13.9%-25.5%); and chronic GVHD at 2 years was 20.8% (95% CI, 14.8%-27.7%). HR matching decreased the probability of severe acute GVHD. The cumulative incidence of relapse at 2 years was 19.9% (95% CI, 14.8%-25.7%). The probabilities of 6-month and 2-year survivals were 67.4% and 49.5%. Unrelated donor cord blood transplantation from partially HLA-mismatched units can cure many children with leukemias. The study was registered at www.clinicaltrials.gov as #NCT00000603.     

Placental/umbilical cord blood for unrelated-donor bone marrow reconstitution: relevance of nucleated red blood cells

Placental/umbilical cord blood (PCB) is a source of hematopoietic stem cells for bone marrow reconstitution. Engraftment speed and survival are related to the total nucleated cell (TNC) dose of the graft. This study explored the possible influence on engraftment of nucleated red blood cells (NRBCs) in the graft. Automated hematology analyzers were used to enumerate TNCs. NRBCs were counted by visual examination or by using an automated analyzer. Hematopoietic progenitor cells were enumerated as either colony-forming cells or CD34(+) cells. Transplant centers reported on transplant outcome in 1112 patients given PCB grafts through September 2001. NRBCs correlated with progenitor cell numbers. Both white blood cell and NRBC dose were independently predictive of myeloid engraftment speed. Because NRBC dose predicted engraftment speed, inclusion of NRBCs in the TNC count does not reduce the effectiveness of the prefreezing TNC count as an index of the quality of a PCB unit as a graft. The correlation between the number of NRBCs and the number of hematopoietic progenitor cells probably reflects the involvement of early stem cells in erythroid responses.     

The impact of post-thaw colony-forming units-granulocyte/macrophage on engraftment following unrelated cord blood transplantation in pediatric recipients

We retrospectively reviewed the engraftment kinetics following unrelated cord blood transplantation (CBT) in association with the post-thaw colony-forming units-granulocyte/macrophage (CFU-GM) number along with the numbers of total nucleated cells (TNC), CD34(+) cells and CD3(+) cells. A total of 71 cord blood units prepared for 53 patients (double-unit CBT in 18 patients) were evaluated. Either the number of infused CFU-GM or CD34(+) cells was significantly lower in patients who failed to achieve engraftment (P=0.028 and 0.005, respectively). Post-thaw CFU-GM, TNC and CD34(+) cells correlated with the speed of neutrophil engraftment (P=0.004, 0.037 and 0.004, respectively), whereas only CFU-GM showed a significant correlation with platelet engraftment (r=-0.385, P=0.024). In double-unit transplants, the number of CFU-GM was the only significant factor predicting engraftment of the predominating unit (P=0.006). We conclude that the post-thaw CFU-GM number is a reliable predictor of rapid engraftment after CBT as well as of the predominating unit in double-unit transplants. Thus, it would be important to perform post-thaw CFU-GM assay on cryopreserved aliquots from several candidate cord blood units in advance before CBT to avoid selecting the unit that might possess a low clonogenic potential.     

Chimerism and T-cell receptor repertoire analysis after unrelated cord blood transplantation with a reduced-intensity conditioning regimen following autologous stem cell transplantation for multiple myeloma

A 65-year-old Japanese male was diagnosed as multiple myeloma with Bence Jones kappa type, clinical stage IIIA. His disease status reached partial remission after chemotherapy. Thereafter, he received tandem transplantation, consisting of high-dose chemotherapy with autologous stem cell transplantation (ASCT), followed by unrelated cord blood transplantation (U-CBT). U-CBT with a reduced-intensity conditioning regimen (RI-CBT) was performed in August 2003. HLA mismatch between the patient and the CBT donor was present at two serological loci (B and DR). A total nucleated CBT cell dose of 2.45 x 10(7)/kg body weight was infused on day 0. Graft-vs.-host disease (GVHD) prophylaxis consisted of cyclosporine A and short-term methotrexate. Neutrophil engraftment (>0.5 x 10(9)/l) was obtained on day 46. He developed positive cytomegalovirus antigenemia, grade II acute GVHD involving skin and liver, varicella-zoster virus infection, septic shock, hemorrhagic cystitis caused by adenovirus and acute hepatitis B virus infection after U-CBT. We retrospectively analyzed T-cell receptor (TCR) repertoire diversity and found that TCR repertoire diversity decreased continuously after U-CBT. Therefore, low-TCR repertoire diversity in this patient appears to be associated with various infections caused by immunodeficiency.