Stem cell transplantation (cord blood transplants)

Gestational Diabetes Mellitus in Pregnancy Increased Erythropoietin Level Affecting Differentiation Potency of Haematopoietic Stem Cell of Umbilical Cord Blood

Background: The in utero environment has many factors that can support cell differentiation. Cytokines, chemokines and growth factors play big roles in haematopoietic mechanisms. Some diseases like gestational diabetes mellitus (GDM) might affect the environment and haematopoietic stem cell (HSC) quality. The aim of this study is to investigate the adverse effects of GDM on umbilical cord blood (UCB) HSC in terms of differentiation potency including the UCB parameters used for banking and transplantation purposes. Methods: UCB-HSC was collected from 42 GDM and 38 normal pregnancies. UCB-HSC was isolated and further enriched using immuno-magnetic separation beads (MACS). The UCB-HSC were cultured in methylcellulose media to investigate the differentiation potency. The level of erythropoietin (EPO) and insulin in the UCB plasma was measured using enzyme linked immunoassay (ELISA) technique. Result: The UCB parameters; volume, total nucleated count (TNC) and total CD34+ cells were significantly reduced in the GDM group compared to the control group. The number of HSC progenitors' colonies were significantly reduced in the GDM group except for progenitor BFU-E, which was significantly increased (GDM = 94.19 ± 6.21, Control = 73.61 ± 2.73, p = 0.010). This data was associated with higher EPO level in GDM group. However, the insulin level in the GDM group was comparable to the Control group. Conclusion: Our results suggest that the changes in the in utero environment due to abnormalities during pregnancy such as GDM might affect the differentiation potency of UCB-HSC. These findings can be considered as an additional parameter for the inclusion and exclusion criteria for UCB banking, particularly for mothers with GDM.

Hypoxia Preconditioning Promotes the Proliferation and Migration of Human Urine-Derived Stem Cells in Chronically Injured Liver of Mice by Upregulating CXCR4

Our previous studies reported that urine-derived stem cells (USCs) possess a strong self-renewal ability and multidirectional differentiation potential and thus are an ideal candidate cell source for hepatocellular transplantation. USC transplantation may repair the pathological changes of chronic liver injury to a certain extent, and hypoxia pretreatment may improve the recovery efficiency of USCs. Therefore, the present study aimed to investigate the possible mechanism of the improved recovery efficiency of hypoxia-pretreated USCs. A chronic liver injury model was established by intraperitoneal injection of carbon tetrachloride into nude mice. USCs were transplanted via caudal vein injection. Hematoxylin and eosin staining and Masson's staining were performed to determine the pathology of the liver. Immunofluorescence and frozen section biopsy were performed to determine differentiation and cell fusion in vivo. Cell coculture was used to detect cell fusion in vitro. The proliferative ability of USCs was evaluated using cell viability and colony formation assays, and the migratory functions of USCs were evaluated using wound healing and transwell assays. The degeneration of hepatocytes and the level of fibrosis in the hypoxia transplantation group were improved compared with the normoxia transplantation group. It was found that exogenous USCs may be differentiated into functional hepatocytes or fused with hepatocytes in vivo. C-X-C motif chemokine (CXC) ligand 12 (CXCL12) expression levels in liver tissue of the chronic liver injury model were upregulated compared with those in the control group. The expression of CXC receptor 4 (CXCR4) in hypoxia-pretreated USCs was also significantly upregulated. The results suggested that USCs fused with different types of liver cells and that hypoxia treatment promoted the fusion rate in vitro by upregulating CXCR4 signaling. Furthermore, hypoxia pretreatment promoted cell proliferation, migration, and cell fusion by inducing CXCR4 signaling, leading to USC-elicited liver tissue recovery following injury in vivo.

Lentiviral Gene Therapy for Bone Repair Using Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells

Umbilical cord blood (UCB) has been increasingly explored as an alternative source of stem cells for use in regenerative medicine due to several advantages over other stem-cell sources, including the need for less stringent human leukocyte antigen matching. Combined with an osteoinductive signal, UCB-derived mesenchymal stem cells (MSCs) could revolutionize the treatment of challenging bone defects. This study aimed to develop an ex vivo regional gene-therapy strategy using BMP-2-transduced allogeneic UCB-MSCs to promote bone repair. To this end, human UCB-MSCs were transduced with a lentiviral vector carrying the cDNA for BMP-2 (LV-BMP-2). In vitro assays to determine the UCB-MSC osteogenic potential and BMP-2 production were followed by in vivo implantation of LV-BMP-2-transduced UCB-MSCs in a mouse hind-limb muscle pouch. Non-transduced and LV-GFP-transduced UCB-MSCs were used as controls. Transduction with LV-BMP-2 was associated with abundant BMP-2 production and induction of osteogenic differentiation in vitro. Implantation of BMP-2-transduced UCB-MSCs led to robust heterotopic bone formation 4 weeks postoperatively, as seen on radiographs and histology. These results, along with the fact that UCB-MSCs can be easily collected with no donor-site morbidity and low immunogenicity, suggest that UCB might be a preferable allogeneic source of MSCs to develop an ex vivo gene-therapy approach to treat difficult bone-repair scenarios.

Clinical outcomes of unrelated cord blood transplantation in children with malignant and non-malignant diseases: Multicenter experience in China

This multicenter retrospective study included 184 children with malignant and non-malignant diseases who underwent UCBT between January 1998 and August 2012. The malignant disease group included 101 children with ALL, AML, CML, JMML, and MDS, and the non-malignant disease group included 83 children with PID, β-thalassemia, IMD BMF, and HLH. The median duration to neutrophil and platelet engraftment was 16 and 35 days in the malignant disease group vs 15 and 38 days in the non-malignant disease group. The cumulative incidence of grade II-IV aGVHD and cGVHD was 25.6% and 13.5% in the malignant disease group vs 19.7% and 11.1% in the non-malignant disease group, respectively. The median duration and cumulative incidence of neutrophil and platelet engraftment, and the cumulative incidence of grade II-IV aGVHD and cGVHD were similar between the two groups. Of the 184 pediatric patients, 114 patients survived during a median follow-up period of 14 months (range 4-138). The 5-year OS and DFS were not statistically different between the two groups (56.3% and 46.1% in malignant disease group vs 68.5% and 52.8% in non-malignant disease group). The above results indicate that UCB is a viable source for HSCT for children with malignant or non-malignant diseases, especially in urgent cases.

Concise review: workshop review: understanding and assessing the risks of stem cell-based therapies

The field of stem cell therapeutics is moving ever closer to widespread application in the clinic. However, despite the undoubted potential held by these therapies, the balance between risk and benefit remains difficult to predict. As in any new field, a lack of previous application in man and gaps in the underlying science mean that regulators and investigators continue to look for a balance between minimizing potential risk and ensuring therapies are not needlessly kept from patients. Here, we attempt to identify the important safety issues, assessing the current advances in scientific knowledge and how they may translate to clinical therapeutic strategies in the identification and management of these risks. We also investigate the tools and techniques currently available to researchers during preclinical and clinical development of stem cell products, their utility and limitations, and how these tools may be strategically used in the development of these therapies. We conclude that ensuring safety through cutting-edge science and robust assays, coupled with regular and open discussions between regulators and academic/industrial investigators, is likely to prove the most fruitful route to ensuring the safest possible development of new products.

Long-term immune reconstitution and infection burden after mismatched hematopoietic stem cell transplantation

Mismatched unrelated donor (MMUD) or umbilical cord blood (UCB) can be chosen as alternative donors for allogeneic stem cell transplantation but might be associated with long-lasting immune deficiency. Sixty-six patients who underwent a first transplantation from either UCB (n = 30) or 9/10 MMUD (n = 36) and who survived beyond 3 months were evaluated. Immune reconstitution was prospectively assessed at sequential time points after transplantation. NK, B, CD4(+), and CD8(+) T cells and their naïve and memory subsets, as well as regulatory T cells (Treg), were studied. Detailed analyses on infections occurring after 3 months were also assessed. The 18-month cumulative incidences of infection-related death were 8% and 3%, and of infections were 72% and 57% after MMUD and UCB transplantation, respectively. Rates of infection per 12 patient-month were roughly 2 overall (1 for bacterial, .9 for viral, and .3 for fungal infections). Memory, naïve CD4(+) and CD8(+)T cells, naïve B cells, and Treg cells reconstitution between the 2 sources were roughly similar. Absolute CD4(+)T cells hardly reached 500 per μL by 1 year after transplantation and most B cells were of naïve phenotype. Correlations between immune reconstitution and infection were then performed by multivariate analyses. Low CD4(+) and high CD8(+)T cells absolute counts at 3 months were linked to increased risks of overall and viral (but not bacterial) infections. When assessing for the naïve/memory phenotypes at 3 months among the CD4(+) T cell compartment, higher percentages of memory subsets were protective against late infections. Central memory CD4(+)T cells protected against overall and bacterial infections; late effector memory CD4(+)T cells protected against overall, bacterial, and viral infections. To the contrary, high percentage of effector- and late effector-memory subsets at 3 months among the CD8(+) T cell compartment predicted higher risks for viral infections. Patients who underwent transplantation from alternative donors represent a population with very high risk of infection. Detailed phenotypic analysis of immune reconstitution may help to evaluate infection risk and to adjust infection prophylaxis.

Human umbilical-cord-blood mononucleated cells enhance the survival of lethally irradiated mice: dosage and the window of time

The purpose of this study was to evaluate the window of time and dose of human umbilical-cord-blood (HUCB) mononucleated cells necessary for successful treatment of radiation injury in mice. Female A/J mice (27-30 weeks old) were exposed to an absorbed dose of 9-10 Gy of (137)Cs γ-rays delivered acutely to the whole body. They were treated either with 1 × 10(8) or 2 × 10(8) HUCB mononucleated cells at 24-52 h after the irradiation. The antibiotic Levaquin was applied 4 h postirradiation. The increased dose of cord-blood cells resulted in enhanced survival. The enhancement of survival in animals that received 2 × 10(8) HUCB mononucleated cells relative to irradiated but untreated animals was highly significant (P < 0.01). Compared with earlier studies, the increased dose of HUCB mononucleated cells, coupled with early use of an antibiotic, extended the window of time for effective treatment of severe radiation injury from 4 to 24-52 h after exposure.

Properties of mechano-transduction via simulated microgravity and its effects on intracellular trafficking of VEGFR's

This study emphasizes the dynamical properties of mechanical loading via simulated microgravity, its effect on acute myeloid leukemia proliferation and hematopoietic stem cell (HSPC) growth and its implications in the area of tissue regeneration. Data presented illustrates that mechanical transduction changes the expression of humoral factors by facilitating paracrine/autocrine signalling, therefore modulating intracellular trafficking of tyrosine kinase receptors. Understanding mechano-transduction in the context of cell and tissue morphogenesis is the major focus of this study. The effects of external physiological stresses, such as blood flow, on several cellular subtypes seem to produce very intricate cellular responses. It is well accepted that mechanical loading plays an intrinsic and extrinsic influence on cell survival. This study shows how microgravity effects hematopoietic stem cells, and human leukemic cell proliferation and expression of its receptors that control cell survival, such as the tyrosine kinase vascular endothelial growth factor receptor-1, receptor-2 and receptor-3.

Validation of cord blood split products prepared by an automated method

OBJECTIVES

In this study, we studied whether the contents of the two compartments of automatically processed cord blood (CB) units are comparable with respect to cell counts and viability and therefore suitable for clinical therapy.

BACKGROUND

CB-derived stem cells are increasingly used for allogeneic transplantation. Many centres prepare the transplants by automated methods allowing to split the product into two portions.

METHODS

CB was collected at different sites in Germany and transported to a single centre for processing. Before and after cryopreservation laboratory analyses were performed to compare the quality of the two CB segments.

RESULTS

In total, 33 products were processed [mean collection volume: 18·6 ± 1·2 mL (range 15·2-20·2 mL) segment A; mean: 4·7 ± 0·3 mL (range 4·2-5·2 mL) segment B]. CD34+ cell counts, viability of CD34+ cells and many other haematological parameters showed a good comparibility between the two segments. However, lymphocyte counts and results of clonogenic assays were significantly different between the two segments of the split product.

CONCLUSION

We conclude that the preparation of the cord blood unit by the automated process results in a homogenous distribution of stem and progenitor cells. However, our findings show that the clonogenic capacity differs between the two segments.

Canine mesenchymal stem cells are effectively labeled with silica nanoparticles and unambiguously visualized in highly autofluorescent tissues

Background

Development of a method for long-term labeling of cells is critical to elucidate transplanted cell fate and migration as well as the contribution to tissue regeneration. Silica nanoparticles have been recently developed and demonstrated to be biocompatible with a high labeling capacity. Thus, our study was designed to assess the suitability of silica nanoparticles for labeling canine mesenchymal stem cells (MSCs) and the fluorescence afficiency in highly autofluorescent tissue.

Results

We examined the effect of silica nanoparticle labeling on stem cell morphology, viability and differentiation as compared with those of unlabeled control cells. After 4 h of incubation with silica nanoparticles, they were internalized by canine MSCs without a change in the morphology of cells compared with that of control cells. The viability and proliferation of MSCs labeled with silica nanoparticles were evaluated by a WST-1 assay and trypan blue exclusion. No effects on cell viability were observed, and the proliferation of canine MSCs was not inhibited during culture with silica nanoparticles. Furthermore, adipogenic and osteogenic differentiation of silica nanoparticle-labeled canine MSCs was at a similar level compared with that of unlabeled cells, indicating that silica nanoparticle labeling did not alter the differentiation capacity of canine MSCs. Silica nanoparticle-labeled canine MSCs were injected into the kidneys of BALB/c mice after celiotomy, and then the mice were sacrificed after 2 or 3 weeks. The localization of injected MSCs was closely examined in highly autofluorescent renal tissues. Histologically, canine MSCs were uniformly and completely labeled with silica nanoparticles, and were unambiguously imaged in histological sections.

Conclusions

The results of the current study showed that silica nanoparticles are useful as an effective labeling marker for MSCs, which can elucidate the distribution and fate of transplanted MSCs.

Eltrombopag, a thrombopoietin receptor agonist, enhances human umbilical cord blood hematopoietic stem/primitive progenitor cell expansion and promotes multi-lineage hematopoiesis

Umbilical cord blood (UCB) transplantation has emerged as a promising therapy, but it is challenged by scarcity of stem cells. Eltrombopag is a non-peptide, thrombopoietin (TPO) receptor agonist, which selectively activates c-Mpl in humans and chimpanzees. We investigated eltrombopag's effects on human UCB hematopoietic stem cell (HSC) and hematopoietic progenitor cell (HPC) expansion, and its effects on hematopoiesis in vivo. Eltrombopag selectively augmented the expansion of human CD45+, CD34+, and CD41+ cells in bone marrow compartment without effects on mouse bone marrow cells in the NOD/SCID mice xenotransplant model. Consequently, eltrombopag increased peripheral human platelets and white blood cells. We further examined effects in the STAT and AKT signaling pathways in serum-free cultures. Eltrombopag expanded human CD34+ CD38-, CD34+, and CD41+ cells. Both eltrombopag and recombinant human TPO (rhTPO) induced phosphorylation of STAT5 of CD34+ CD41-, CD34- CD41+, and CD34- CD41- cells. rhTPO preferentially induced pSTAT3, pAKT, and more pSTAT5 in CD34- C41+ cells, while eltrombopag had no effects on pSTAT3. In conclusion, eltrombopag enhanced expansion of HSCs/HPCs of human UCB in vivo and in vitro, and promoted multi-lineage hematopoiesis through the expansion of bone marrow HSCs/HPCs of human UCB in vivo. Eltrombopag differed somewhat from rhTPO in the signal transduction pathways by favoring earlier HSC/HPC populations.

Effect of the surface density of nanosegments immobilized on culture dishes on ex vivo expansion of hematopoietic stem and progenitor cells from umbilical cord blood

Umbilical cord blood (UCB) is an attractive source of hematopoietic stem and progenitor cells for hematopoietic stem cell (HSC) transplantation. However, the low number of HSCs obtainable from a single donor of UCB limits direct transplantation of UCB to the treatment of pediatric patients. In this study, we investigated the ex vivo expansion of HSCs cultured on biomaterials grafted with several nanosegments, i.e. polyamine, fibronectin, RGDS, and CS1 (EILDVPST), at several surface densities. No direct correlation was found between fold expansion of HSCs and physical parameters of the culture dishes, i.e. surface roughness and water contact angle of the culture dishes. However, a small amount of grafted amino groups, less than 0.8 residual μmol cm(-2), on the dishes was effective for the ex vivo expansion of HSCs. A high amount of grafted amino groups hindered the ex vivo expansion of HSCs on the dishes. HSCs cultured on dishes with a high concentration of CS1 (2.40 residual μmol cm(-2)) showed greater expansion of HSCs and more pluripotent colony-forming units (i.e. colony-forming unit-granulocyte, erythroid, macrophage, and megakaryocyte (CFU-GEMM)) than those on fibronectin-grafted and polyamine-grafted dishes. These data suggest that the specific interaction between HSCs and CS1 helps to maintain the pluripotency of HSCs during the ex vivo expansion of HSCs.

Improving T-cell therapy for relapsed EBV-negative Hodgkin lymphoma by targeting upregulated MAGE-A4

PURPOSE

Patients with Hodgkin lymphoma (HL) relapsing after hematopoietic stem cell transplant have limited options for long-term cure. We have shown that infused cytotoxic T cells (CTL) targeting Epstein Barr virus (EBV)-derived proteins induced complete remissions in EBV(+) HL patients. A limitation of this approach is that up to 70% of relapsed HL tumors are EBV-negative. For these patients, an alternative is to target the cancer/testis antigen MAGE-A4 present in EBV antigen-negative HL tumors. Furthermore, epigenetic modification by clinically available demethylating agents can enhance MAGE-A4 expression in previously MAGE-negative tumors.

EXPERIMENTAL DESIGN

We explored the feasibility of combining adoptive T cell therapy with epigenetic modification of tumor antigen expression. We further characterized MAGE-A4-specific T-cell phenotype and function, and examined the effects of the epigenetic modifying drug decitabine on these T cells.

RESULTS

Cytotoxic T cells were generated specifically recognizing MAGE-A4 expressed by autologous HL targets and tumor cell lines. Decitabine-previously shown to increase tumor antigen expression in HL-did not compromise MAGE-A4-specific T-cell phenotype and function. In patients treated with decitabine, expanded MAGE-A4-specific T cells had a broader antitumor T cell repertoire, consistent with increased antigen stimulation in vivo.

CONCLUSIONS

Adoptive transfer of MAGE-A4-specific T cells, combined with epigenetic modifying drugs to increase expression of the protein, may improve treatment of relapsed HL.

Does the time between collecting and processing umbilical cord blood samples affect the quality of the sample?

OBJECTIVE

To assess the association between the time from umbilical cord blood collection until processing and the quality of the sample.

METHODS

Umbilical cord blood samples collected during the third stage of labor were placed in temperature-controlled boxes for the transport of biological material and sent to an umbilical cord blood bank, where the number of nucleated cells, viable cells and CD34+ cells were counted, and samples were additionally tested for contamination at the following time intervals: up to 24 hours, up to 48 hours and up to 72 hours following sampling. Data were analyzed using the multivariate analysis of variance (MANOVA) and compared using McNemar's χ2 test. Significance was defined at p < 0.05.

RESULTS

Means and medians of the number of nucleated cells, viable cells and CD34+ cells decreased significantly (p < 0.0001) as a function of the increased time between sampling and analysis, the difference between 24 and 48 hours being less than the difference between 24 and 72 hours. A linear correlation was found between the mean number of viable cells and CD34+ cells at the three moments of analysis. Contamination testing was negative in all samples.

CONCLUSION

The increase in time interval from sampling until analysis negatively affected the number of nucleated cells, viable cells and CD34+ cells but was not associated with specimen contamination. A linear correlation was found between decrease in the number of viable cells and CD34+ cells.

Culture and differentiation of osteoblasts on coral scaffold from human bone marrow mesenchymal stem cells

In this paper we describe an approach that aims to provide fundamental information towards a scientific, biomechanical basis for the use of natural coral scaffolds to initiate mesenchymal stem cells into osteogenic differentiation for transplant purposes. Biomaterial, such as corals, is an osteoconductive material that can be used to home human derived stem cells for clinical regenerative purposes. In bone transplantation, the use of biomaterials may be a solution to bypass two main critical obstacles, the shortage of donor sites for autografts and the risk of rejection with allograft procedures. Bone regeneration is often needed for multiple clinical purposes for instance, in aesthetic reconstruction and regenerative procedures. Coral graft Porites lutea has been used by our team for a decade in clinical applications on over a thousand patients with different bone pathologies including spinal stenosis and mandibular reconstruction. It is well accepted that human bone marrow (hBM) is an exceptional source of mesenchymal stem cells (MSCs), which may differentiate into different cell phenotypes such as osteoblasts, chondrocytes, adipocytes, myocytes, cardiomyocytes and neurons. Isolated MSCs from human bone marrow were induced into osteoblasts using an osteogenic medium enriched with two specific growth factors, FGF9 and vitamin D2. Part of the cultured MSCs were directly transferred and seeded onto coral scaffolds (Porites Lutea) and induced to differentiate into osteoblasts and part were cultured in flasks for osteocell culture. The data support the concept that hBM is a reliable source of MSCs which may be easily differentiated into osteoblasts and seeded into coral as an optimal device for clinical application. Within this project we have also discussed the biological nature of MSCs, their potential application for clinical transplantation and the prospect of their use in gene therapy.

Successful treatment of refractory Langerhans cell histiocytosis with pulmonary aspergillosis by reduced-intensity conditioning cord blood transplantation

The prognosis of multisystem LCH in children with risk organ involvement is extremely poor when they fail to respond to conventional chemotherapy. In such patients, allogeneic SCT may produce complete and sustained remission; however, high-dose myeloablative regimens are frequently associated with treatment-related morbidity and mortality. More recently, allogeneic SCT following an RIC regimen has been performed as an alternative salvage approach. We describe a nine-month-old boy with refractory multisystem LCH with pulmonary aspergillosis who was successfully treated with reduced-intensity cord blood transplantation.

Downstream targets of HOXB4 in a cell line model of primitive hematopoietic progenitor cells

Enforced expression of the homeobox transcription factor HOXB4 has been shown to enhance hematopoietic stem cell self-renewal and expansion ex vivo and in vivo. To investigate the downstream targets of HOXB4 in hematopoietic progenitor cells, HOXB4 was constitutively overexpressed in the primitive hematopoietic progenitor cell line EML. Two genome-wide analytical techniques were used: RNA expression profiling using microarrays and chromatin immunoprecipitation (ChIP)-chip. RNA expression profiling revealed that 465 gene transcripts were differentially expressed in KLS (c-Kit(+), Lin(-), Sca-1(+))-EML cells that overexpressed HOXB4 (KLS-EML-HOXB4) compared with control KLS-EML cells that were transduced with vector alone. In particular, erythroid-specific gene transcripts were observed to be highly down-regulated in KLS-EML-HOXB4 cells. ChIP-chip analysis revealed that the promoter region for 1910 genes, such as CD34, Sox4, and B220, were occupied by HOXB4 in KLS-EML-HOXB4 cells. Side-by-side comparison of the ChIP-chip and RNA expression profiling datasets provided correlative information and identified Gp49a and Laptm4b as candidate "stemness-related" genes. Both genes were highly ranked in both dataset lists and have been previously shown to be preferentially expressed in hematopoietic stem cells and down-regulated in mature hematopoietic cells, thus making them attractive candidates for future functional studies in hematopoietic cells.

4-1BB and CD28 signaling plays a synergistic role in redirecting umbilical cord blood T cells against B-cell malignancies

Umbilical cord blood (UCB) T cells can be redirected to kill leukemia and lymphoma cells by engineering with a single-chain chimeric antigen receptor (CAR) and thus may have general applications in adoptive cell therapy. However, the role of costimulatory molecules in UCB T-cell activation and effector functions in context with CAR remains elusive. To investigate the effect of costimulatory molecules (4-1BB and CD28) on UCB T cells, we transduced UCB T cells with lentiviral vectors expressing Green Fluorescent Protein (GFP) and CAR for CD19 containing an intracellular domain of the CD3zeta chain and either a 4-1BB (UCB-19BBzeta) or a CD28 intracellular domain (UCB-1928zeta), both (UCB-1928BBzeta), or neither (UCB-19zeta). We found that UCB-19BBzeta and UCB-28BBzeta T cells exhibited more cytotoxicity to CD19(+) leukemia and lymphoma cell lines than UCB-19zeta and UCB-1928zeta, although differences in secretion of interleukin-2 and interferon-gamma by these T cells were not evident. In vivo adoptive transfer of these T cells into intraperitoneal tumor-bearing mice demonstrated that UCB-19BBzeta and UCB-1928BBzeta T cells mounted the most potent antitumor response. The mice adoptively transferred with UCB-1928BBzeta cells survived longer than the mice with UCB-19BBzeta. Moreover, UCB-1928BBzeta T cells mounted a more robust antitumor response than UCB-19BBzeta in a systemic tumor model. Our data suggest a synergistic role of 4-1BB and CD28 costimulation in engineering antileukemia UCB effector cells and implicate a design for redirected UCB T-cell therapy for refractory leukemia.

Functionally active virus-specific T cells that target CMV, adenovirus, and EBV can be expanded from naive T-cell populations in cord blood and will target a range of viral epitopes

The naive phenotype of cord blood (CB) T cells may reduce graft-versus-host disease after umbilical cord blood transplantation, but this naivety and their low absolute numbers also delays immune reconstitution, producing higher infection-related mortality that is predominantly related to CMV, adenovirus (Adv), and EBV. Adoptive immunotherapy with peripheral blood-derived virus-specific cytotoxic T lymphocytes (CTLs) can effectively prevent viral disease after conventional stem cell transplantation, and we now describe the generation of single cultures of CTLs from CB that are specific for multiple viruses. Using EBV-infected B cells transduced with a clinical-grade Ad5f35CMVpp65 adenoviral vector as sources of EBV, Adv, and CMV antigens, we expanded virus-specific T cells even from CB T cells with a naive phenotype. After expansion, each CTL culture contained both CD8(+) and CD4(+) T-cell subsets, predominantly of effector memory phenotype. Each CTL culture also had HLA-restricted virus-specific cytotoxic effector function against EBV, CMV, and Adv targets. The CB CTLs recognized multiple viral epitopes, including CD4-restricted Adv-hexon epitopes and immunosubdominant CD4- and CD8-restricted CMVpp65 epitopes. Notwithstanding their naive phenotype, it is therefore possible to generate trivirus-specific CTLs in a single culture of CB, which may be of value to prevent or treat viral disease in CB transplant recipients. This study is registered at www.clinicaltrials.gov as NCT00078533.

Update on umbilical cord blood transplantation

PURPOSE OF REVIEW

2008 marks the 20th anniversary of the first use of umbilical cord blood (UCB) as a source of donor cells for hematopoietic stem cell transplantation. In those early days, there was great doubt and skepticism about the utility of UCB as a source of hematopoietic stem cells. Doubts about whether UCB, containing 10-20x fewer cells than bone marrow, had sufficient cells to durably engraft a myeloablated patient and, after demonstration that engraftment occurred with less graft-versus-host disease, whether it would confer graft-versus-leukemia activity were raised.

RECENT FINDINGS

Transplantation with UCB is effective in the treatment of children with hematological malignancies, marrow failure, immunodeficiencies, hemoglobinopathies and inherited metabolic diseases. Transplantation without full human leukocyte antigen matching is possible and, despite a lower incidence of graft-versus-host disease, graft-versus-leukemia is preserved. The number of cells in a single UCB can be limiting, but the use of two UCBs for a single transplant shows promise to overcome this obstacle.

SUMMARY

Cord blood transplantation is now an established field with enormous potential. UCB increases access to transplantation therapy for many patients unable to identify a fully matched adult donor. In the future, it may emerge as a source of cells for cellular therapies focused on tissue repair and regeneration.

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.

Umbilical cord-blood transplantations from unrelated donors in patients with inherited metabolic diseases: Single-institute experience

We evaluated the feasibility of UCBT from unrelated donors and a myeloablative preparative regimen that did not involve anti-thymocyte globulin in five children with lysosomal and peroxisomal diseases. Patients with MPS II (n = 1), adrenoleukodystrophy (n = 1), metachromatic leukodystrophy (n = 2), and Krabbe disease (n = 1) received UCBT between December 2001 and September 2005. All patients received oral Bu (600 mg/m2), CY (200 mg/kg IV), and fludarabine (180 mg/m2 IV). Prophylaxis for GVHD consisted of a combination of tacrolimus and a short methotrexate course. Neutrophil engraftment occurred a median of 24 days (range, 21-25) after transplantation. None had graft rejection. One patient developed grade III acute GVHD and the other four patients had grade I acute GVHD; none had extensive chronic GVHD. One patient developed hemorrhagic cystitis. There were no treatment-related deaths. Although one child with MPS II died of PTLD 10 months after the UCBT, four of the five children are alive 14, 20, 31, and 55 months after transplantation with complete donor chimerism. These results suggest the feasibility of the UCBT with Bu, fludarabine, and CY-preparative regimen for patients with inherited metabolic diseases.

Chaotic dynamic stabilities and instabilities of hematopoietic stem cell growth plasticity

The hematopoietic system consists of: (1) a network of stem and progenitor cells of varying degrees of maturity interacting with other cells that possess supportive and regulatory capacities and (2) vascular stem cell niches with supporting stem cells in their self-renewal, proliferation, differentiation, and mobilization to the circulation. Recent data suggest that selective expression of organ-specific chemokines promotes the mobilization of bone-marrow-derived pluripotent cells, a process that is essential for tissue vascularization and organ regeneration. Despite intensive investigation, the pathways by which mechanical signals are converted to biochemical responses are not completely understood. Recent studies have suggested that chromatin shifts and cell cycle effects stem cell gene expression, and thus results in changes of its surface receptor expression at different points of the cell cycle machinery, therefore changing cell cycle transit. This review will attempt to discuss new approaches to determine the regulation of stem cell growth and differentiation by underlying the significance of the chaotic dynamics of transcriptional networks within a cell, with a combination of chemokines and cytokines in the environment, and mechanical forces, such as: stretch, strain and laminar flow, all involving both cooperation and competition.

Pneumonia caused by Moraxella catarrhalis in haematopoietic stem cell transplant patients. Report of two cases and review of the literature

Moraxella catarrhalis is a gram negative diplococcus that causes a variety of upper and lower respiratory tract infections. Patients with malignant, hematological disorders treated with intensive cytotoxic chemotherapy, and recipients of various forms of haematopoietic stem cell transplant receiving immunosuppressive agents are at high risk of developing severe infections and septic complications. Early detection of the organism and prompt treatment with appropriate antibiotics provide both resolution of the infection and prevention of further consequences. Two patients with haematopoietic stem cell transplant who developed pneumonia caused by M. catarrhalis at King Faisal Specialist Hospital and Research Centre in Riyadh are reported and the literature is reviewed. To our knowledge, these are the first case reports of M. catarrhalis pneumonia in haematopoietic stem cell transplant patients.

Reduced intensity allogeneic umbilical cord blood transplantation in children and adolescent recipients with malignant and non-malignant diseases

There is a significant amount of morbidity and mortality following myeloablative umbilical cord blood transplantation (UCBT). Reduced intensity (RI) conditioning offers an alternative to myeloablative conditioning before UCBT. We investigated RI-UCBT in 21 children and adolescents with malignant (n=14), and non-malignant diseases (n=7). RI conditioning consisted of fludarabine (150-180 mg/m2) with either busulfan (< or = 8 mg/kg)+rabbit antithymocyte globulin (R-ATG; n=16) or cyclophosphamide+R-ATG+/-etoposide (n=5). Human leukocyte antigen match: 4/6 (n=13), 5/6 (n=5) and 6/6 (n=3). The median total nucleated cell and CD34+ cell dose per kilogram were 3.58 x 10(7) and 2.54 x 10(5), respectively. The median time for neutrophil and platelet engraftment was 17.5 and 52 days, respectively. There were six primary graft failures (chronic myelogenous leukemia (CML), beta-thalassemia, hemophagocytic lymphohistiocytosis (HLH) and myelodysplastic syndrome (MDS)). The probability of developing grade II to grade IV acute graft-versus-host disease (GVHD) and chronic GVHD was 28.6 and 16.7%, respectively. Incidence of transplant-related mortality (TRM) was 14%. The 5 years overall survival (OS) in all patients was 59.8%. The 5 years OS for patients with average versus poor-risk malignancy was 77.8 versus 22.2% (P=0.03). RI-UCBT may result in graft failure in specific high-risk chemo-naïve patients (CML, beta-thalassemia, HLH and MDS), but in more heavily pretreated pediatric and adolescent recipients results in rapid engraftment and may be associated with decreased severe GVHD and TRM.

Outcomes of hematopoietic stem cell transplantation for Hurler's syndrome in Europe: a risk factor analysis for graft failure

Hurler's syndrome (HS), the most severe form of mucopolysaccharidosis type-I, causes progressive deterioration of the central nervous system and death in childhood. Allogeneic stem cell transplantation (SCT) before the age of 2 years halts disease progression. Graft failure limits the success of SCT. We analyzed data on HS patients transplanted in Europe to identify the risk factors for graft failure. We compared outcomes in 146 HS patients transplanted with various conditioning regimens and grafts. Patients were transplanted between 1994 and 2004 and registered to the European Blood and Marrow Transplantation database. Risk factor analysis was performed using logistic regression. ‘Survival’ and ‘alive and engrafted’-rate after first SCT was 85 and 56%, respectively. In multivariable analysis, T-cell depletion (odds ratio (OR) 0.18; 95% confidence interval (CI) 0.04–0.71; P=0.02) and reduced-intensity conditioning (OR 0.08; 95% CI 0.02–0.39; P=0.002) were the risk factors for graft failure. Busulfan targeting protected against graft failure (OR 5.76; 95% CI 1.20–27.54; P=0.028). No difference was noted between cell sources used (bone marrow, peripheral blood stem cells or cord blood (CB)); however, significantly more patients who received CB transplants had full-donor chimerism (OR 9.31; 95% CI 1.06–82.03; P=0.044). These outcomes may impact the safety/efficacy of SCT for ‘inborn-errors of metabolism’ at large. CB increased the likelihood of sustained engraftment associated with normal enzyme levels and could therefore be considered as a preferential cell source in SCT for ‘inborn errors of metabolism’.

Flt3 ligand expands lymphoid progenitors prior to recovery of thymopoiesis and accelerates T cell reconstitution after bone marrow transplantation

Deficient thymopoiesis and retarded recovery of newly developed CD4(+) T cells is one of the most important determinants of impaired immunocompetence after hemopoietic stem cell transplantation. Here we evaluated whether Fms-like tyrosine kinase 3 (Flt3) ligand (FL) alone or combined with IL-7 affects T cell recovery, thymopoiesis, and lymphoid progenitor expansion following bone marrow transplantation in immunodeficient mice. FL strongly accelerated and enhanced the recovery of peripheral T cells after transplantation of a low number of bone marrow cells. An additive effect on T cell recovery was not observed after coadministration of IL-7. Lineage(-)sca-1(+)c-kit(+)flt3(+) lymphoid progenitor cell numbers were significantly increased in bone marrow of FL-treated mice before recovery of thymopoiesis. Thymocyte differentiation was advanced to more mature stages after FL treatment. Improved T cell recovery resulted in better immunocompetence against a post-bone marrow transplantation murine CMV infection. Collectively, our data suggest that FL promotes T cell recovery by enhanced thymopoiesis and by expansion of lymphoid progenitors.

Effects of HOXB4 Overexpression on Ex Vivo Expansion and Immortalization of Hematopoietic Cells from Different Species

Overexpression of the human HOXB4 has been shown to induce the expansion and self-renewal of murine hematopoietic stem cells. In preparation for clinical studies, we wished to investigate the effects of HOXB4 on cells from other species, in particular preclinical large animals such as dogs and nonhuman primates. Thus, we transduced CD34(+) cells from nonhuman primates, dogs, and humans with a HOXB4-expressing gammaretroviral vector and a yellow fluorescent protein-expressing control vector. Compared with the control vector, HOXB4 overexpression resulted in a much larger increase in colony-forming cells in dog cells (28-fold) compared with human peripheral blood, human cord blood, and baboon cells (two-, four-, and fivefold, respectively). Furthermore, we found that HOXB4 overexpression resulted in immortalization with sustained growth (>12 months) of primitive hematopoietic cells from mice and dogs but not from monkeys and humans. This difference correlated with increased levels of retrovirally overexpressed HOXB4 in dog and mouse cells compared with human and nonhuman primate cells. The immortalized cells did not show any evidence of insertional mutagenesis or chromosomal abnormalities. Competitive congenic transplantation experiments showed that HOXB4-expanded mouse cells engrafted well after 1 or 3 months of expansion, and no leukemia was observed in mice. Our findings suggest that the growth promoting effects of HOXB4 are critically dependent on HOXB4 expression levels and that this can result in important species-specific differences in potency. Disclosure of potential conflicts of interest is found at the end of this article.

Circulating stem cells in extremely preterm neonates

AIM

To measure circulating CD34+ cell levels in premature neonates and to correlate the initial CD34+ counts with measures of pulmonary function and neonatal morbidity.

METHODS

CD34+ cell counts were measured in the peripheral blood of preterm neonates (gestational ages 24-32 weeks) ventilated for respiratory disease at <48 h of life, and at the start of the 2nd, 3rd and 4th weeks of life. Data pertaining to neonatal demographics and short-term outcomes were collected. Pulmonary function tests were performed to coincide with CD34+ sampling.

RESULTS

Thirty preterm neonates with median gestational age of 24 weeks and birth weight of 641 g were analysed. A mean of 99.4 CD34+ cells per microliter was observed in the 1st week of life with a decline to 54.4 cells per microliter by the 4th week. An inverse correlation between initial CD34+ count and gestational age (p=0.01) was observed. No significant correlations were observed with measures of pulmonary function or neonatal morbidities.

CONCLUSIONS

Extremely premature neonates have remarkably high levels of CD34+ cells in their peripheral blood at birth. Umbilical cord blood from this population may potentially provide an abundant source of hematopoietic stem and progenitor cells for therapeutic purposes.

Isolation of stem cells from human umbilical cord blood

Umbilical cord blood (UCB) is gaining more prominence in recent times as a source of non-embryonic multipotent stem cells. Global annual human birth rate (100 million) presents UCB as the largest non-controversial stem cell source, with an added advantage of naive immune status. Cord blood stem cells are routinely utilized in stem cell transplantation in leukemia patients and carry huge potential to treat other human diseases with less concern of rejection. Because UCB contains low number of stem cells, their use is associated with significant delays in engraftment of neutrophils and platelets. Development of reliable methods for isolation and expansion of cord blood stem cells is critical for consequent clinical application. The focus of this chapter is to review the methods currently used by different research groups and to recommend an isolation protocol that yields optimal number of UCB stem cells.

Transplantation of vascular endothelial cells mediates the hematopoietic recovery and survival of lethally irradiated mice

Flk-1(+) endothelial progenitors contribute critically to the definitive onset of hematopoiesis during embryogenesis. Recent studies have suggested that adult sources of endothelial cells also possess hematopoietic activity. In this study, we sought to determine whether transplantation of primary vascular endothelial cells (ECs) could enhance the hematopoietic recovery and survival of irradiated mice. C57Bl6 mice were exposed to sublethal and lethal doses of irradiation and were subsequently given transplants of either primary murine brain-derived ECs (MBECs) or fetal blood-derived ECs (FBECs). Mice that received a transplant with MBECs alone demonstrated accelerated BM cellular recovery, radioprotection of BM c-kit(+)sca-1(-)lin(-) progenitors and enhanced regeneration of c-kit(+)sca-1(+)lin(-) (KSL) stem/progenitor cells following irradiation compared with controls. MBEC transplantation also facilitated the recovery of circulating white blood cell and platelet counts following radiation exposure. Remarkably, 57% of mice that received a transplant with MBECs alone survived long term following 1050 cGy exposure, which was 100% lethal in control mice. FBEC transplantation was also associated with increased survival compared with controls, although these mice did not survive in the long term. These data suggest that reestablishment of endothelial cell activity can improve the hematopoietic recovery and survival of irradiated mice.

Highly efficient ex vivo expansion of human hematopoietic stem cells using Delta1-Fc chimeric protein

Ex vivo expansion of hematopoietic stem cells (HSCs) has been explored in the fields of stem cell biology, gene therapy, and clinical transplantation. Here, we demonstrate efficient ex vivo expansion of HSCs measured by long-term severe combined immunodeficient (SCID) repopulating cells (SRCs) from human cord blood CD133-sorted cells using a soluble form of Delta1. After a 3-week culture on immobilized Delta1 supplemented with stem cell factor, thrombopoietin, Flt-3 ligand, interleukin (IL)-3, and IL-6/soluble IL-6 receptor chimeric protein (FP6) in a serum- and stromal cell-free condition, we achieved approximately sixfold expansion of SRCs when evaluated by limiting dilution/transplantation assays. The maintenance of full multipotency and self-renewal capacity during culture was confirmed by transplantation to nonobese diabetic/SCID/gammac(null) mice, which showed myeloid, B, T, and natural killer cells as well as CD133(+)CD34(+) cells, and hematopoietic reconstitution in the secondary recipients. Interestingly, the CD133-sorted cells contained approximately 4.5 times more SRCs than the CD34-sorted cells. The present study provides a promising method to expand HSCs and encourages future trials on clinical transplantation.

Umbilical cord blood transplantation and banking

Umbilical cord blood transplantation (UCBT) is an expanding practice for both pediatric and adult patients. Rapid availability, low risk of infectious disease transmission, lower risk of graft-versus-host disease, and lack of risk for the donor makes UCB an attractive alternative source of hematopoietic stem cells for transplantation. We review the state of the art of pediatric and adult UCBT and important aspects of UCB banking. Current strategies to improve clinical results and expand access to UCBT to a larger number of adult patients are discussed. New approaches to enhance hematopoietic recovery by the use of accessory cells or direct intra-bone marrow injection are also reviewed.

Trends in haematopoietic cell transplantation for inborn errors of metabolism

For the last 25 years, haematopoietic cell transplantation (HCT) has been used as effective therapy for selected inborn errors of metabolism (IEMs), mainly lysosomal storage diseases and peroxisomal disorders. The main rational for HCT in IEMs is based on the provision of correcting enzymes by donor cells within and outside the blood compartment. The ultimate goal of HCT is to achieve a normal or near-normal life and normal neurodevelopment. HCT has been performed for more than 20 diseases. Only for Hurler syndrome, X-ALD and infantile Krabbe disease, are detailed studies available suggesting that HCT is indicated for carefully selected cases. Improvement of transplantation techniques and alternative therapies may change the recommended (contra-)indications for IEM. A recent example of emerging transplantation techniques is the fast availability of unrelated cord blood (UCB). UCB makes HCT feasible in patients with rapidly progressive neurological diseases. Because of the fast availability of UCB and therefore the ability to transplant shortly after diagnosis, there is no indication for patients in a moderate/good clinical condition to receive enzyme replacement therapy (ERT; in Hurler syndrome) prior to or during HCT and can ERT only be considered in patients with poor clinical condition. Mesenchymal stem cell infusions with HCT is an emerging technique, and might be interesting in halting the remaining defects after successful HCT. Improvement in HCT techniques and novel stem cell sources will significantly impact the safety and efficacy of this therapy as well as expand the list of candidate disorders. A good functioning worldwide registry would be necessary to measure the effects of the procedures performed in more detail.