George Paterakis - Academia.edu (original) (raw)

Papers by George Paterakis

Journal of Hematotherapy & Stem Cell Research, Dec 1, 2000

ABSTRACT The 5-transmembrane receptor AC133 is expressed on a subpopulation of human hematopoieti... more ABSTRACT The 5-transmembrane receptor AC133 is expressed on a subpopulation of human hematopoietic cells that includes the CD34(bright) cells. We evaluated the developmental potential of AC133+CD34(bright) and AC133(dim/-)CD34+ cells isolated from 5 cord blood (CB) samples by studying the in vitro proliferative and differentiative potential of each population in both progenitor and mature cell expansion cultures. Seven-day culture of AC133+CD34(bright) cells with a cytokine combination favoring primitive progenitor cells causes a significant increase in CD34+, CFU-C and noncycling stem/progenitor cells HPP-Q (High Proliferative Potential-Quiescent), whereas culture of AC133(dim/-)CD34+ cells shows a limited increase in committed progenitor cells only. HPP-Q cells were not found in freshly isolated AC133(dim/-)CD34+ nor in expanded CD34+ cells derived from AC133(dim/-)CD34+ cells. No statistically significant difference was observed between the 1-week expanded AC133+ and the initial AC133+CD34(bright) cells regarding their clonogenic efficiency (CE), while expanded CD34+ cells derived from AC133(dim/-)CD34+ cells exhibited a decreased CE. Subexpansion of the reselected AC133+ derived from AC133+CD34(bright) cells reveals a further increase of stem/progenitor cells and the 14-day expanded AC133+ cells reveal an unchanged CE. Subexpansion of reselected 7-day CD34+ cells derived from AC133(dim/-)CD34+ cells was not possible. Culture of AC133+CD34(bright) cells in cytokines that favor megakaryopoiesis or erythropoiesis resulted in a significant expansion of CD41+ and CD71+ cells, respectively; AC133(dim/-)CD34+, in comparison, showed a limited potential to megakaryocytic differentiation and a decreased production of erythroid cells. Our data indicate that early high proliferating stem/progenitor cells and early committed progenitors are present in AC133+CD34(bright) cells, but not in AC133(dim/-)CD34+ cells; the latter represent late committed progenitors with limited proliferative potential.

Leukemia Research, Jul 1, 2002

Letter to the editor Unusually prolonged survival of a case of acute megakaryoblastic leukemia se... more Letter to the editor Unusually prolonged survival of a case of acute megakaryoblastic leukemia secondary to long-standing polycythemia vera Kostas Stamatopoulos a,∗, Xenophon Yataganas a, Theodora Papadaki b, George Paterakis c a Department of Medicine, University of Athens, Athens, Greece b Hemopathology Department, Evangelismos Hospital, Athens, Greece c Immunology Laboratory, G. Gennimatas Hospital, Athens, Greece

PubMed, Dec 1, 1996

The thalassaemias are a heterogeneous group of genetic haemoglobin disorders. The use of the Sysm... more The thalassaemias are a heterogeneous group of genetic haemoglobin disorders. The use of the Sysmex R- 1000 instrument in their study during the last 5 years has proved valuable. 1 Reticulocyte percentage and absolute counts were estimated in heterozygous beta-thalassaemia, in beta thalassaemia intermedia and in sickle beta thalassaemia and were compared with normal controls. Reticulocyte maturation subpopulations (high, middle and low fluorescence ratio) were assessed and compared with those of other haematological disorders. Red cell size and non-specific auramine-O binding were shown to be factors affecting mature red cell autofluorescence. 2 Nucleated red blood cells (NRBC) interfere with leucocyte counts in most haematology analysers. The upper particle count (UPP), provided by the R-1000 with modified fluorescence amplification voltage, appeared to produce a direct NRBC count in beta-thalassaemia intermedia when compared to NRBC counts assessed indirectly. 3 Erroneous platelet counts are reported by most haematology analysers in thalassaemia intermedia (especially in haemoglobin H disease) due to extensive microcyte-platelet interference and cause problems in diagnosis and management. Platelet counts provided by the R-1000 instrument in such patients were comparable to counts assessed by microscopy. Flow cytometric analysis by the Sysmex R-1000 instrument is useful in thalassaemia syndromes not only for providing precise reticulocyte counts and reticulocyte maturation data, but for direct NRBC counting and accurate platelet enumeration in cases of thalassaemia intermedia.

Bone Marrow Transplantation, Jul 18, 2005

Stromal tissue derived from adult bone marrow (BM) contains clonogenic progenitor cells (CFU-F), ... more Stromal tissue derived from adult bone marrow (BM) contains clonogenic progenitor cells (CFU-F), some of which are considered to be multi-potent MSCs, capable of differentiating into a range of mesenchymal cell lineages. Current methods for the isolation of BM-MSCs rely upon the rapid adhesion of the stromal progenitor populations to tissue culture plastic and their subsequent rapid proliferation in vitro, 2 resulting, however, in a heterogeneous starting population of adherent BM cells. A significant proportion of the latter represent adherent monocytic cells, the major cause of false-positive results in studies investigating the origin of BM-stromal cells following SCT. In addition, BM-MNCs from patients post allogeneic transplantation show a significant impairment in the ability to generate confluent SC-layers in long-term Dexter-type cultures preventing molecular assessment of chimerism. Therefore, studies based on these methods are limited by monocyte-macrophage contamination and defective SC growth. Recent studies have demonstrated that positive selection using a commercialized anti-endoglin (CD105) antibody enables to obtain homogenous SC-cultures to be obtained without contamination with hematopoietic-derived cells. We hypothesized that cultures initiated with immunomagnetically isolated BM-CD105 þ cells, a cell fraction enriched in mesenchymal progenitor cells (MPC), from patients after hematopoietic SCT would efficiently generate SC-layers without cells of hematopoietic origin, suitable for accurate SC-chimerism analysis. We chose to use the anti-CD105 monoclonal antibody for MPC enrichment for two reasons: First, it was the only commercially available antibody for direct immunomagnetic positive selection of MPCs and secondly preliminary work in our lab has shown that a sample of 4-5 ml BM would be enough for obtaining SC-layers in cultures supplemented with bFGF. We obtained 4-6 ml BM samples from 12 patients 1-24 months post matched sibling allogeneic SC. Five of these patients had suffered from b-thalassemia and the rest from malignant hematological diseases. Initially, we performed immunomagnetic isolation of BM-CD105 þ cells with a cell recovery rate of 0.270.12%. Two immunophenotypic types of CD105 þ cells were detected: (1) CD105 þ GlycophorinA þ CD45 À (22.574.2%), 'erythroid cells' phenotype, (2) CD105 þ GlycophorinA À CD45 low/moderate (20.676.8%), 'mesenchymal cells' phenotype. Further flow cytometric analysis of MACS-isolated cells demonstrated no CD14, CD19, CD31, or CD10 expression. Light microscopic examination of cytospins prepared with freshly

Annals of Hematology, Oct 1, 1991

Precise reticulocyte counts are difficult to obtain by the manual method when their percentage in... more Precise reticulocyte counts are difficult to obtain by the manual method when their percentage in the blood is low or normal. In these instances, rapid reticulocyte counting by flow cytometry appears to offer more accuracy and precision. The purpose of this study was to establish reticulocyte counts in heterozygous beta-thalassemia for reference purposes and to evaluate the performance of the recently introduced apparatus R-1000 (Sysmex) in the very heterogeneous thalassemic and sickle-cell syndromes. We studied a total of 364 samples; 102 heterozygous beta-thalassemia carriers, 180 normal matched controls, 36 patients with thalassemia major or intermedia, and 46 patients with various sickle-cell syndromes. Reticulocyte counts (both as percentage and as total number) were higher in heterozygous beta-thalassemia than in normal controls (p less than 0.001) and showed an inverse correlation with the respective hemoglobin values (p less than 0.001). These results confirm the proposed slightly increased erythropoietic activity in heterozygous beta-thalassemia carriers. A drawback of the technique is that the reticulocyte-platelet discrimination error is signaled frequently in all conditions displaying a marked red cell heterogeneity, especially when these are associated with high reticulocyte numbers. This calls probably for readjustment of the corresponding algorithm. In addition, all these conditions show a significantly increased auramine-O mature red-cell nonspecific fluorescence.

British Journal of Haematology, Aug 1, 1996

The study of immunoglobulin heavy chain gene rearrangements in multiple myeloma has revealed exte... more The study of immunoglobulin heavy chain gene rearrangements in multiple myeloma has revealed extensive divergence from the germline sequences, but no intraclonal diversity with disease evolution. Our study investigated the state of the rearranged • light chain variable region (V•) gene segments, as well as abortive V• family gene usage in cases of multiple myeloma expressing ¸light chain. We studied 11 cases of • and five cases of ¸light chain-expressing multiple myeloma. Total cellular RNA was extracted from the bone marrow of patients with overt disease and subjected to reverse transcription-polymerase chain reaction (RT-PCR) analysis to amplify clonally rearranged variable region sequences. Direct nucleotide sequencing by the dideoxy-chain termination method was performed on the RT-PCR products. We did not observe preferential usage of certain V• gene families. Mutation frequencies of the V• segments varied in number. In the majority of cases, extensive somatic mutations occurred within the complementarity determining regions (CDRs) of V•, whereas only a limited degree of divergence from the germline was observed in others. In all cases studied, replacement mutations tended to cluster in the CDRs, a finding compatible with an antigen-driven somatic hypermutation process. In 3/5 cases of ¸light-chain expressing multiple myeloma, abortively rearranged V• gene segments were amplified from genomic DNA; in two cases a nontemplated nucleotide insertion rendering the V• sequences out-of-frame was observed, and in the third a stop codon was identified in the open reading frame of the V• sequence. Somatic mutations were observed in all cases of abortive V• genes studied; however, their distribution does not suggest selection by antigen. We conclude that somatic mutations observed in the V• regions of myeloma cells are of variable extent and suggest operation of the antigen selection process. Lack of or minimal somatic hypermutation in a few cases may be in some way implicated in the biological heterogeneity of the disease.

Journal of Combustion, Aug 9, 2018

An investigation of ultralean stratified, disk stabilized, propane flames operated with acoustic ... more An investigation of ultralean stratified, disk stabilized, propane flames operated with acoustic modulation of the inlet velocity and fuel-air mixture profiles is presented. Transverse acoustic forcing was applied to the air, upstream of a double-cavity premixer section, formed along three concentric disks, which fueled the stabilization region with a radial mixture gradient. Measurements and supporting Large Eddy Simulations with a nine-step mechanism for propane combustion were performed to evaluate variations in the ultralean flame characteristics under forced and unforced conditions. The effects of forcing on the heat release profiles and on the interaction of the toroidal flame with the recirculation region are examined and discussed. The impact of the acoustic excitation of inlet conditions on the local extinction behavior is, also, assessed by monitoring a local stability criterion and by analyzing phase-resolved chemiluminescence images.

Fuel, 2018

The present work is a part of a larger experimental campaign which examines the behaviour of vari... more The present work is a part of a larger experimental campaign which examines the behaviour of various fuels on a swirl stabilized flame burner configuration. Overall, detailed speciation measurements and temperature measurements were combined with optical measurements. The work presented here concerns the part of the experimental campaign which deals with the optical characteristics of the examined flames. The work adds to the growing database of experimental measurements assessing engine-relevant reaction environments which shift from traditional ones in order to meet pollutant emission regulations and efficiency standards. Here, the oxidation of several commonly used fuel and fuel surrogates that are subjected to the addition of a bio-derived fuel additive (dimethyl ether) and emulated exhaust gas recirculation (EGR) is studied in a laboratory-scale swirl stabilized burner. The natural flame chemiluminescence has been exploited to selectively measure line of sight CH* and OH* profiles for combinations of these fuels and reaction environments. As a result, the geometry and intensity of the reaction and oxidation zones have been parametrically evaluated for

Journal of Energy Engineering, 2016

AbstractThe work describes an experimental investigation of propane flames established through fu... more AbstractThe work describes an experimental investigation of propane flames established through fuel injection and gradual premixing with preheated and vitiated oxidizing air, within a double-cavity arrangement, formed along a cylinder and two concentric disks. Ignition of the inlet stratified and vitiated mixture and flame stabilization is established at the recirculation region of the afterbody disk. Measurements of mean velocities, temperatures, OH* and CH* chemiluminescence and gas analysis provided information for the interpretation of the relative variations in flame structure and burner performance. The study illustrates some aspects regarding the influence of the preheated/vitiated conditions on the combustion of the inlet stratified fuel-air mixture profile, with respect to flame front stabilization, disposition, and burner emissions. Some important differences in the vitiated flame structure and topology are discussed in comparison to the unvitiated case characteristics, in an initial effort to e...

Journal of Combustion, 2013

The work presents comparisons of the flame stabilization characteristics of axisymmetric disk and... more The work presents comparisons of the flame stabilization characteristics of axisymmetric disk and 2D slender bluff-body burner configurations, operating with inlet mixture stratification, under ultralean conditions. A double cavity propane air premixer formed along three concentric disks, supplied with a radial equivalence ratio gradient the afterbody disk recirculation, where the first flame configuration is stabilized. Planar fuel injection along the center plane of theleading faceof a slender square cylinder against the approach cross-flow results in a stratified flame configuration stabilized alongside the wake formation region in the second setup. Measurements of velocities, temperatures,OH∗andCH∗chemiluminescence, local extinction criteria, and large-eddy simulations are employed to examine a range of ultralean and close to extinction flame conditions. The variations of the reacting front disposition within these diverse reacting wake topologies, the effect of the successive s...

Blood, 2007

The value and exact type of intensive chemotherapy of unselected elderly AML patients in terms of... more The value and exact type of intensive chemotherapy of unselected elderly AML patients in terms of overall survival (OS) and quality of life remains controversial. Despite recent improvements in supportive measures during cytotoxic therapy, elderly AML patients continue to exhibit lower remission rates, higher toxicity, more relapses and eventually a worse survival. The present analysis evaluates in a retrospective manner the outcome of 57 homogeneously treated AML patients >60yrs during a period of 70 months (Nov 2001 to Aug 2007). The protocol schedule included an initial course of mitoxantrone+ cytarabine 3+5 (12mg/m2/d and 100mg/m2 q12h respectively) followed by a second abbreviated course of mitoxantrone+ cytarabine 2+5, followed by a final course of idarubicin+cytarabine+ thioguanine 2+7+7 (10mg/m2/d, 100mg/m2 q12h and 100mg/m2/d respectively). G-CSF at 5μg/Kg was added to all courses to accelerate hematopoietic recovery. Our patient population consisted of 30 cases of de no...

Blood, Nov 16, 2004

Immunoglobulin kappa (IGK) locus rearrangements were analyzed in 164 κ-light chain (LC) expressin... more Immunoglobulin kappa (IGK) locus rearrangements were analyzed in 164 κ-light chain (LC) expressing chronic lymphocytic leukemia (CLL) cases and 95 λ-LC expressing CLL cases. In κ-CLL, 151 IGKV-J transcripts were successfully amplified by RT-PCR; 147/151 were in frame; four out-of-frame IGKV-J transcripts were heavily mutated and contained one or more stop codons, presumably introduced by somatic hypermutation; in all four cases the corresponding expressed transcript was also mutated. DNA-PCR identified 24/164 κ-CLL cases (15%) with double IGKV-J rearrangements; 9/24 non-expressed IGKV-J rearrangements were in-frame; 3/9 were mutated. The most frequently used IGKV genes in expressed IGKV-J rearrangements were: 3–20, 1-39/1D-39, 1–5 and 4-1; the IGKV4-1 gene was by far the most frequent in non-expressed IGKV-J rearrangements (9/24 cases, 33%). In λ-CLL, a total of 65 IGKV-J rearrangements were amplified in 59/95 cases (62.0%); six cases had two different rearrangements. IGVK4-1 was the most frequently used gene (14/65 sequences, 21.5%), followed by IGKV1-16 (8 cases,12.3%), 1-33/1D-33 and 2-30 (7 cases each, 10.8%). IGKV-J transcripts were detected by RT-PCR in 10/59 λ-CLL cases with IGKV-J rearrangements, of which four were in-frame and six out-of-frame. Seven IGKV-J rearrangements in λ-CLL had less than 100% homology to germline; 3/7 were in-frame; 6/7 patients had mutated IGHV and 5/7 had mutated IGLV genes. In κ-CLL, biased usage of the IGKJ1/IGKJ2 genes was observed both in expressed (69%) and non-expressed rearrangements (78%); in contrast, in λ-CLL, downstream IGKJ (IGKJ3-5) usage was observed in 32/59 sequences (53%). Nonproductive rearrangements involving the kappa deleting element (KDE) that render the IGK locus inactive were also analyzed. In κ-CLL, 22/147 cases (15%) carried IGKV to KDE rearrangements, while 24/147 cases (16.5%) carried IGKJ-C- INTRON (JKI) to KDE rearrangements. In λ-CLL, IGKV-KDE rearrangements were amplified in 55/94 cases (59%); JKI-KDE rearrangements were amplified in 52/94 cases (56%). IGKV1D-43 was the most frequent gene in IGKV-KDE joints in κ-CLL (4/22 cases); in contrast, the most frequent genes in IGKV-KDE joints in λ-CLL were IGKV3-20 and IGKV2-30 (9/55 and 7/55 cases, respectively). In conclusion, the present study confirms IGK locus rearrangements in the vast majority of λ-LC expressing CLL cases. Differential usage of IGKJ genes along with significant IGKV repertoire differences in both IGKV-J and IGKV-KDE rearrangements between κ- and λ-CLL allude to prolonged IGK locus recombination before CLL clonogenic cells became λ-producers. The inactivation of productive and potentially functional IGKV-J joints by secondary rearrangements indicates a role for receptor editing in shaping the expressed IG repertoire in CLL. Finally, the identification of mutated, non-expressed IGKV-J rearrangements both in κ- and λ-CLL might be considered as evidence for secondary rearrangements occurring after the onset of somatic hypermutation, at least in a proportion of cases.

Pediatric Research, May 1, 1997

Stem Cells, Apr 1, 2006

Using the novel stem cell marker CD133, a functional hierarchy within the CD34 ϩ cell population ... more Using the novel stem cell marker CD133, a functional hierarchy within the CD34 ϩ cell population has been described, indicating that CD133 ϩ CD34 ϩ cells are enriched in primitive and myeloid progenitors, whereas CD133 Ϫ CD34 ϩ cells are committed mainly to the B-cell and erythroid lineages [1, 2]. Interestingly, among CD133 ϩ cells, a small cell subset has been found that did not coexpress CD34 or any other lineage-specific marker. Further work on these cells has shown that CD133 ϩ CD34 Ϫ Lin Ϫ cells are the most primitive blood cells identified to date [3]. Of note, a CD133 ϩ CD34 Ϫ Lin ϩ cell subset in fresh bone marrow, peripheral blood, or cord blood (CB) has never been detected, in contrast to the CD133 Ϫ CD34 ϩ Lin ϩ subset that comprises about 30% of the total CD34 ϩ cell population [2]. In expansion cultures, however, it has already been observed that CD133 ϩ CD34 ϩ cells generate both CD133 Ϫ CD34 ϩ and CD133 ϩ CD34 Ϫ cells [4-7]. The latter subset's identity as a biologically distinct stage in the hematopoietic cell hierarchy has not been further investigated to date. We isolated CB CD133 ϩ cells (n ϭ 12) by using the MACS-AC133 Isolation Kit (Miltenyi Biotech, Bergisch Gladbach, Germany, http:// www.miltenyibiotech.com) and subsequently cultured them in StemSpan medium (StemCell Technologies,

$Research paper thumbnail of Insights from the Greek experience of the use of Blinatumomab in pediatric relapsed and refractory acute lymphoblastic leukemia patients$

Neoplasma, 2021

Pediatric refractory or relapsed acute lymphoblastic leukemia (ALL) poses unique therapeutic chal... more Pediatric refractory or relapsed acute lymphoblastic leukemia (ALL) poses unique therapeutic challenges, with novel immunotherapy approaches offering potential cure opportunities. In this frame, the use of Blinatumomab may induce durable remissions, serving as a successful bridge to allogeneic hematopoietic stem cell transplantation (allo-HSCT). Herein, we retrospectively summarize the Greek experience on pediatric relapsed/refractory B-cell precursor ALL patients that were treated with Blinatumomab in a compassionate, off-label setting as an effort to achieve disease clearance and proceed to allo-HSCT. In our cohort of 9 patients, 6/9 (66.7%) responded to Blinatumomab, achieving complete morphological remission (CR) after the 1st cycle, while minimal/measurable residual disease (MRD)-negativity (<10-4) after the 1st cycle was achieved in 2/2 patients (100.0%) with prior CR. A successful bridge to HSCT was feasible in 5/9 patients (55.6%). Median relapse-free survival (RFS) was 3.0 months (range 0.5-21.4 months) and median overall survival (OS) was 8.7 months (range 1.4-47.1 months) for the whole pediatric cohort. There was a trend of prolonged survival among patients who achieved MRD response after the 1st Blinatumomab administration. MRD response (defined as the >=2-log reduction of MRD value before and after Blinatumomab administration), was associated with a median RFS/OS of 7.4/7.6 months, while lack of MRD response was associated with a median RFS/OS of 0.5/3.0 months, respectively. Novel therapeutic maneuvers, in order to overcome disease resistance, i.e. increased usage of Blinatumomab dose (45 μg/m 2 /day), combination with donor lymphocyte infusions (DLIs), use of other immunotherapy salvage approaches (inotuzumabozogamicin), are herein discussed. Additionally, the optimal number of Blinatumomab cycles, the CD19-negative relapses and lineage switch, are also addressed. Our data although referred to a limited, however refractory or relapsed and heavily pretreated number of patients, strongly suggest that Blinatumomab may well induce sustained remissions and serve as an effective bridge to HSCT. Whether immunotherapy combined with chemotherapy can outweigh the need for subsequent allo-HSCT, if incorporated into frontline high-risk ALL therapy, remains an optimistic issue to be verified in future randomized clinical trials.

Blood, 2014

ETV6/RUNX1 rearrangement, being the most common genetic abnormality in childhood ALL, is combined... more ETV6/RUNX1 rearrangement, being the most common genetic abnormality in childhood ALL, is combined with controversial prognostic behavior and frequent late relapses, indicating the need for identification of additional prognostic markers. In our study, we examined the relation between ETV6/RUNX1 and presenting clinical/biological features, co-existing subclones/secondary aberrations, early response to treatment (MRD) and their impact on outcome in a pediatric cohort of 133 ALL pts , treated in one Center over a 12-year period. Data from 133 newly diagnosed ALL pts(83 males) with a median age of 5.1 yrs(range 1.2-16.7), have been retrospectively recorded and analyzed. Pts were consecutively diagnosed and homogeneously treated on BFM based protocols during the years 2000-2011. FISH evaluation using commercial probe sets was performed for the detection of ETV6-RUNX1, E2A-PBX1, BCR-ABL fusion genes, MLL gene rearrangements as well as ETV6, RUNX1, CDKN2A/2B and other gene duplications, de...

Blood, 2004

Hydroxyurea (HU) is a widely used cytotoxic agent that is known to induce fetal hemoglobin (HbF) ... more Hydroxyurea (HU) is a widely used cytotoxic agent that is known to induce fetal hemoglobin (HbF) production. HU-induced HbF production is beneficial for some patients with β-thalassemia and also ameliorates the severity of pain episodes in sickle cell anemia. Various cell culture systems have been used to elucidate the implicated mechanisms. We have previously demonstrated in both K562 human erythroleukemic cells and human erythroid cells (hAEC) that HU increases the transcription of low-expressed globin genes as well as the splicing efficiency of primary globin transcripts; however, other post-transcriptional effects could not be excluded. In this study, we extended our analysis in order to further understand the effect of HU on erythropoiesis and the molecular mechanisms involved in globin gene elevation. Peripheral blood hAEC from normal individuals were cultured in a two-phase liquid culture. Erythropoietin was added only to phase II. Erythroid cells in phase II were exposed to ...

International Journal of Laboratory Hematology, 2008

This study was designed to maximize the recovery of the desirable cell populations contained in t... more This study was designed to maximize the recovery of the desirable cell populations contained in the cord blood (CB) freezing bag, in order to optimize donor selection for adolescents and adults. To evaluate this hypothesis, high volume CB units (CBUs) were categorized into three volume collection groups (120-139, 140-159 and >or=160 ml) and were randomly split before volume reduction into two half low volume CBUs; (a) and (b). Using the SEPAX Cell Processing System, all CBUs were standardized to 26 ml. In 128 high volume split CBUs, the WBC, mononuclear cell and CD34+ cell recoveries were significantly higher (P <or= 0.05; 80%, 79.89% and 87.41% respectively) than those of the 106 high volume nonsplit CBUs (59.7%, 62.82% and 68.62% respectively), resulting in significantly higher (P <or= 0.05) mean weights of the potential recipients. The strategy of splitting high volume CBUs into two half low volume CBUs improves the recovery of the cells and is an attractive option for ex vivo expansion, in order to facilitate the CB transplantation in adults who are not eligible for single CB transplantation because of limitations of cell dose.