CD9 shapes glucocorticoid sensitivity in pediatric B-cell precursor acute lymphoblastic leukemia.

Resistance to glucocorticoids (GC), the common agents for remission induction in pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL), poses a significant therapeutic hurdle. Therefore, dissecting the mechanisms shaping GC resistance could lead to new treatment modalities. Here, we showed that CD9- BCP-ALL cells were preferentially resistant to prednisone and dexamethasone over other standard cytotoxic agents.

Pharmacogenomic Profiling of Pediatric Acute Myeloid Leukemia to Identify Therapeutic Vulnerabilities and Inform Functional Precision Medicine.

Unlabelled: Despite the expanding portfolio of targeted therapies for adults with acute myeloid leukemia (AML), direct implementation in children is challenging due to inherent differences in underlying genetics. Here we established the pharmacologic profile of pediatric AML by screening myeloblast sensitivity to approved and investigational agents, revealing candidates of immediate clinical relevance. Drug responses ex vivo correlated with patient characteristics, exhibited age-specific alterations, and concorded with activities in xenograft models.

R4 RGS proteins suppress engraftment of human hematopoietic stem/progenitor cells by modulating SDF-1/CXCR4 signaling.

Homing and engraftment of hematopoietic stem/progenitor cells (HSPCs) into the bone marrow (BM) microenvironment are tightly regulated by the chemokine stromal cell-derived factor-1 (SDF-1) and its G-protein-coupled receptor C-X-C motif chemokine receptor 4 (CXCR4), which on engagement with G-protein subunits, trigger downstream migratory signals. Regulators of G-protein signaling (RGS) are GTPase-accelerating protein of the Gα subunit and R4 subfamily members have been implicated in SDF-1-directed trafficking of mature hematopoietic cells, yet their expression and influence on HSPCs remain mostly unknown. Here, we demonstrated that human CD34+ cells expressed multiple R4 RGS genes, of which RGS1, RGS2, RGS13, and RGS16 were significantly upregulated by SDF-1 in a CXCR4-dependent fashion.

Double-unit unrelated cord blood transplantation for thalassemia major: Comparison with HLA-identical sibling bone marrow transplantation.

UCBT recipients with TM are at high risk of EF related to low number of stem cells and prior alloimmunization after multiple blood transfusions. Here, we evaluated the safety and efficacy of double-unit UCBT using TT-containing conditioning regimens in TM. Retrospective analysis of children who underwent double-unit UCBT for TM in the Prince of Wales Hospital between August 2007 and January 2017, and outcome of double-unit UCBT for TM was compared with outcome of HLA-matched sibling BMT.

CD9 blockade suppresses disease progression of high-risk pediatric B-cell precursor acute lymphoblastic leukemia and enhances chemosensitivity.

CD9 has been implicated in cancer progression but its prognostic relevance and therapeutic potential in B-cell precursor acute lymphoblastic leukemia (BCP-ALL) are largely unknown. In a cohort of pediatric BCP-ALL patients, we found that CD9 cases had a significantly lower 5-year relapse-free survival rate than CD9 cases. Multivariate analysis demonstrated that CD9 positivity independently predicted inferior survival outcomes, and could be applied with established prognostic features, including prednisone response and cytogenetic status, to refine patient stratification.

Indiscernible Benefit of Double-Unit Umbilical Cord Blood Transplantation in Children: A Single-Center Experience From Hong Kong.

Double-unit umbilical cord blood (DU-UCB) may extend the use of UCB transplantation and improve clinical outcomes. Data in the literature show that single-unit dominance happened in a vast majority of recipients, and the mechanism is unknown. We examined the clinical relevance and engraftment kinetics of DU-UCB transplant in 65 consecutive children who underwent unrelated single-unit (n = 25) and double-unit (n = 40) UCB transplantation for various hematological malignancies (n = 45) and nonmalignant disorders (n = 20).

Isolated persistent elevation of alanine transaminase for early diagnosis of pre-symptomatic Wilson's disease in Chinese children.

Background: Recent studies presented a contradictory approach for the investigation of pediatric patients with an isolated increase in alanine transaminase. While classical teaching advised for a thorough investigation, recent studies suggested the yield on further investigation was low and thus not necessary. Yet the approach to the same clinical problem may need to be different due to variable disease prevalence rates among different ethnic populations.

Humoral response to conjugate pneumococcal vaccine in paediatric oncology patients.

Objective: Pneumococcal conjugate vaccine (PCV) is an effective way to prevent invasive pneumococcal diseases in high risk populations. The efficacy of this vaccine in paediatric oncology patients remains unknown.

Design And Setting: The authors evaluated the antibody response to seven pneumococcal serotypes in paediatric oncology patients given two doses of heptavalent PCV (PCV-7).

Recovery of humoral and cellular immunities to vaccine-preventable infectious diseases in pediatric oncology patients.

The recovery of antibodies to various vaccine-preventable infectious diseases, humoral and cellular immunity in pediatric oncology patients were evaluated by a prospective longitudinal study for 18 months. Lymphocyte subset (CD3+, CD4+, CD8+, CD16/56+, CD19+), CD4/CD8 ratio, immunoglobulin levels, antibodies to diphtheria, pertussis, tetanus, hepatitis B, measles, mumps, and rubella were measured serially at 6 months till 18 months after stopping all chemotherapy (including maintenance chemotherapy). Twenty-eight children (hematological malignancies, n = 14; solid tumors, n = 14) were studied.

Humoral immune response after post-chemotherapy booster diphtheria-tetanus-pertussis vaccine in pediatric oncology patients.

Background: The role of post-chemotherapy booster vaccination in pediatric oncology children remains to be established. In this randomized controlled study, we studied the effect of immune responses to diphtheria-tetanus-pertussis (DTP) booster vaccination in children 6 months after completing chemotherapy.

Methods: Children 1-18 years old with chemotherapy completed for 6 months (baseline) were eligible.

The plant mannose-binding lectin NTL preserves cord blood haematopoietic stem/progenitor cells in long-term culture and enhances their ex vivo expansion.

Ex vivo expansion of haematopoietic stem and progenitor cells in cytokine combinations is effective in promoting differentiation and proliferation of multilineage progenitor cells, but often results in reduction of self-renewable stem cells. This study investigated the effect of a mannose-binding lectin, NTL, purified from Narcissus tazetta var. chinensis, on prolonged maintenance and expansion of cord blood CD34+ cells.

Promoting effects of serotonin on hematopoiesis: ex vivo expansion of cord blood CD34+ stem/progenitor cells, proliferation of bone marrow stromal cells, and antiapoptosis.

Serotonin is a monoamine neurotransmitter that has multiple extraneuronal functions. We previously reported that serotonin exerted mitogenic stimulation on megakaryocytopoiesis mediated by 5-hydroxytryptamine (5-HT)2 receptors. In this study, we investigated effects of serotonin on ex vivo expansion of human cord blood CD34+ cells, bone marrow (BM) stromal cell colony-forming unit-fibroblast (CFU-F) formation, and antiapoptosis of megakaryoblastic M-07e cells.

Small peptide analogue of SDF-1alpha supports survival of cord blood CD34+ cells in synergy with other cytokines and enhances their ex vivo expansion and engraftment into nonobese diabetic/severe combined immunodeficient mice.

The SDF-1/CXCR4 axis has been implicated in the chemotaxis, homing, mobilization, and expansion of hematopoietic stem and progenitor cells. We studied the effects of a SDF-1 peptide analogue CTCE-0214 on the survival of cord blood CD34+ cells in culture, expansion, and engraftment of expanded cells in the nonobese diabetic/severe combined immunodeficient (NOD/SCID) mouse model. Our results demonstrated that CTCE-0214 synergized with thrombopoietin (TPO), stem cell factor (SCF), or flt-3 ligand (FL) on the survival of stem and progenitor cells in culture.

Arsenic trioxide mediates intrinsic and extrinsic pathways of apoptosis and cell cycle arrest in acute megakaryocytic leukemia.

Arsenic trioxide (ATO) induces apoptosis in a range of solid tumors and leukemia cells, and has been clinically applied for the treatment of acute promyelocytic leukemia with confirmed efficacy. Acute megakaryocytic leukemia (AMKL) is an aggressive malignancy with poor prognosis, if bone marrow transplantation is not possible. In this study, we applied flow cytometry, Western blot analysis and microarray techniques to investigate the effects of ATO on apoptosis and the cell division cycle of AMKL cell lines CHRF-288-11 and MEG-01.

Preclinical ex vivo expansion of G-CSF-mobilized peripheral blood stem cells: effects of serum-free media, cytokine combinations and chemotherapy.

Objectives: Ex vivo expansion of granulocyte-colony stimulating factor (G-CSF)-mobilized peripheral blood stem cells (PBSC) is a promising approach for overcoming the developmental delay of bone marrow (BM) reconstitution after transplantation. This project investigated the effects of culture duration, serum-free media, cytokine combinations, and chemotherapy on the outcomes of expansion.

Methods: Enriched CD34+ cells were cultured for 8 or 10 d in serum-free media (QBSF-60 or X-Vivo 10) and four combinations of cytokines consisting of recombinant human pegylated-megakaryocyte growth and development factor, stem cell factor, flt-3 ligand, G-CSF, interleukin (IL)-6, platelet-derived growth factor (PDGF), and IL-1beta.

Interleukin-1beta up-regulates the expression of thrombopoietin and transcription factors c-Jun, c-Fos, GATA-1, and NF-E2 in megakaryocytic cells.

The multifunctional cytokine interleukin-1beta (IL-1beta) plays a central role in the body's immune and inflammatory responses. The mechanism of IL-1beta on thrombocytosis and megakaryocytopoiesis has remained controversial. In previous reports, we have demonstrated the expression of IL-1 receptors (IL-1RI and IL-1RII) and enhancing effects of IL-1beta on primary human megakaryocytic (MK) cells.

Thrombospondin-1 induces apoptosis in primary leukemia and cell lines mediated by CD36 and Caspase-3.

Thrombospondin-1 (TSP-1) is a naturally occurring anti-angiogenic compound that induces apoptosis of endothelial and cancer cells via its receptor CD36. The objectives of our study were to investigate the in vitro effects of TSP-1 on the apoptosis of primary human leukemia cells as well as leukemia cell lines and the possible mechanism involving CD36. Our results demonstrated that TSP-1 induced apoptosis in CD36 positive cell lines CHRF-288-11, Meg-01 and HL-60, but not CD36 negative K562, at a dose-dependent manner as demonstrated by DNA ladder formation, Annexin V and propidium iodide (PI) stainings.

Effects of oxygen-induced lung damage on megakaryocytopoiesis and platelet homeostasis in a rat model.

The association between lung injury and thrombocytopenia was investigated by comparing the megakaryocyte and platelet counts, and platelet activation using P-selectin as a marker, between the prepulmonary (right atrial) and postpulmonary (left atrial) blood in adult and neonatal (preterm and term) rats with and without hyperoxic lung injury. In the healthy controls, the postpulmonary blood had lower megakaryocyte count (prepulmonary versus postpulmonary: Preterm: 8.7[0.

Detection of micrometastasis of neuroblastoma to bone marrow and tumor dissemination to hematopoietic autografts using flow cytometry and reverse transcriptase-polymerase chain reaction.

Background: The identification of neuroblastoma metastases to bone marrow (BM) is requisite in staging disease for risk-adopted therapy. However, micrometastases were not elucidated fully.

Methods: Flow cytometry (FCM) with CD45/CD56/CD81 and reverse transcriptase-polymerase chain reactions (RT-PCR) for tyrosine hydroxylase (TH) transcripts were used to evaluate neuroblastoma in bilateral BM aspirates at diagnosis, BM autografts, peripheral blood stem cell (PBSC) collections, and CD34(+) cell products of 27 children.

Thrombospondin-1 inhibits in vitro megakaryocytopoiesis via CD36.

Thrombospondin-1 (TSP-1) is an inhibitor of angiogenesis, inducing apoptosis of the endothelial cells via CD36 signaling mechanism. We investigated CD36 expression and the effect of TSP-1 on megakaryocytopoiesis, with and without pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF), and with and without blocking TSP-1 binding with receptor CD36 on megakaryocytic cells. Our data showed that TSP-1 induced a dose-dependent growth inhibition in both murine and human colony forming unit-megakaryocyte (CFU-MK) assays and significantly counteracted the mitogenic effect from PEG-rHuMGDF.

Platelet-derived growth factor up-regulates the expression of transcription factors NF-E2, GATA-1 and c-Fos in megakaryocytic cell lines.

Platelet-derived growth factor (PDGF) is a platelet alpha-granule protein. In previous reports, we demonstrated the expression of PDGF receptors on platelets and megakaryocytic cells and that PDGF enhanced the proliferation of megakaryocytic progenitor cells. In this study, we investigated the effects of PDGF on mRNA and protein expressions of megakaryocyte-associated transcription factors, c-Fos, GATA-1, NF-E2 and PU.

[The Immunological Study of Megakaryocytes].

The immunological role of megakaryocytes is not well known. This project studies the involvement of megakaryocytes on immuno-inflammatory processes and the possible mechanism via the adhesion molecule CD36 and the synthesis of relevant cytokines. The expression of adhesion protein CD36 on human platelets, megakaryocytes and megakaryocytic cell lines (Meg-01, Dami, CHRF-288-11 and M-07e) was analyzed by using flow cytometry, ELISA and immunocytochemical methods.

Trehalose ameliorates the cryopreservation of cord blood in a preclinical system and increases the recovery of CFUs, long-term culture-initiating cells, and nonobese diabetic-SCID repopulating cells.

Background: The cryopreservation of HPCs in DMSO has been practiced by cord blood (CB) banks worldwide. Inevitably, some detriment to biologic function occurs as the result of freezing injuries and DMSO toxicity. Trehalose, a disaccharide, is a natural cryoprotectant in organisms capable of surviving extreme dehydration and cold.

Mixed chimerism after bone marrow transplantation for thalassemia major.

Thirty-four thalassemia patients were studied for chimerism by fluorescent in situ hybridization or variable number tandem repeats after bone marrow transplantation. Mixed chimerism was detected in 9 patients with host cells ranging from 4 to 56%. One had graft rejection and the others were transfusion independent.

Is the timing of exposure to infection a major determinant of acute lymphoblastic leukaemia in Hong Kong?

The hypothesis that protection of infants from exposure to infectious agents with delayed first exposure to one or more specific agents together contribute to the aetiology of childhood leukaemia, especially common acute lymphoblastic leukaemia (cALL), has substantial indirect support from descriptive epidemiology and case-control studies in developed Western countries. A case-control study of childhood leukaemia diagnosed at ages 2-14 years has now been conducted in Hong Kong. Cases (n=98) formed a consecutive series of Chinese children diagnosed with acute leukaemia; controls (n=228) were identified following a survey using random digit dialling and required to attend for medical examination by a paediatrician.