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Biomedical subjects

C E Walsh

Publications and source records attributed to C E Walsh.

At least 37 records · Page 2Linked to original sources

Retroviral mediated gene transfer of the Fanconi anemia complementation group C gene to hematopoietic progenitors of group C patients.

Fanconi Anemia (FA) is a rare genetic disorder characterized by progress pancytopenia, congenial abnormalities, and a predisposition to malignancy. Therapy is currently limited to allogeneic marrow transplantation; patients lacking a suitable donor usually die from aplasia or acute leukemia. Recently, mutation in a novel gene named FACC (Fanconi anemia C-complementing) has been identified as causing one type of FA. FACC mutations, which introduce splicing errors or stop codons, have been identified in approximately 15% of FA patients. We have recently been successful in functional complementation of four FA cell lines using retroviral vectors to transfer a copy of the normal FACC gene. We also analyzed the ability of our viral vectors to functionally correct hematopoietic progenitor cells from a patient bearing a splice donor mutation. As for the lymphoid cell lines, these CD34-enriched cells were extremely sensitive to MMC. After infection of these progenitor cells with viral vectors bearing normal FACC, the progenitors gave rise to increased numbers of colonies both in the absence and presence of up to 5nM MMC, whereas control cells were completely destroyed by 1nM MMC. In summary, we have demonstrated that: (1) retroviral vectors can be engineered to transfer a normal FACC gene to FA(C) lymphoid cell lines and primary hematopoietic cells; (2) introduction of a normal FACC gene into CD34+ progenitors markedly enhances their growth in the absence and presence of MMC. This study is designed to determine whether hematopoietic progenitors transduced with the normal FACC gene can be reinfused safely into FA(C) patients. CD34+ cells obtained from G-CSF mobilized peripheral blood will be transduced ex vivo over a 72-hour period in the presence of IL-3, IL-6, and Stem Cell Factor with the FACC retroviral vector. These transduced cells will be reinfused into FA(C) patients. Patients will be monitored for toxicities as well as evidence of successful gene transfer and expression. The procedure will be repeated up to a total of 4 times with each treatment 2-4 months apart. Theoretically, these rescued stem cells should have a selective growth advantage within the hypoplastic FA marrow environment in vivo.

Cell Cycle Proteins↗

Cancer gene therapy using a novel adeno-associated virus vector expressing human wild-type p53.

Previous studies have indicated that transfer of wild-type (wt) p53 cDNA into cancer cells can suppress the tumor phenotype in vitro and in vivo. In this study we examined the effects of wt p53 transduction in the human cancer cell line H-358 (that bears a homozygous deletion of p53) using a novel recombinant adeno-associated viral vector engineered to express wt p53 (rAAVp53). Western blot analysis demonstrated the expression of wt p53 in H-358 cells following infection with rAAVp53. Furthermore, rAAVp53 inhibited the growth of the neoplastic cells and also mediated cytotoxicity. Cell cycle analysis of rAAVp53-infected cells showed a significant increase in the percentage of cells arrested at the G1-S checkpoint. H-358 cells infected with rAAVp53 underwent apoptosis as demonstrated by the morphological appearance of DAPI-stained nuclei. Direct injection of rAAVp53 into H-358 tumors implanted subcutaneously in immunodeficient nu/nu mice inhibited tumor growth completely in three of the five animals tested. Mock-infected and rAAV control treated tumors showed no growth inhibition. In situ staining in nu/nu mice detected the presence of wild-type p53 protein in residual tumor cells following rAAVp53 administration. The impressive in vivo efficacy of the rAAVp53 suggests a bystander effect. We conclude that rAAV may be effective as a gene transfer vector in the delivery of p53 to cancer cells.

Animals↗

The Fanconi anemia complementation group C gene (FAC) suppresses transformation of mutant fibroblasts by the SV40 virus.

Fanconi anemia (FA) is a heterogeneous genetic syndrome manifested by bone marrow failure and consisting of at least five complementation groups (A, B, C, D, E). Mutations in a gene termed FAC are responsible for the C complementation group, but the function of the FAC protein remains obscure. FA patients are also highly cancer-prone; the molecular basis for this susceptibility is unclear but has led to the hypothesis that the wild-type FA gene may act as a tumor suppressor. In vitro, mutant FA primary fibroblasts are 3- to 50-fold more sensitive than normal fibroblasts to transformation in culture by the SV40 virus. We confirmed this marked susceptibility to transformation of a FAC-mutant primary fibroblast cell line, GM449. We then introduced a copy of the wild-type FAC cDNA into GM449 cells using a recombinant adeno-associated virus (rAAV) vector. We found that GM449 cells transduced with a copy of the normal FAC cDNA by a FAC-rAAV vector were at least 10-fold less prone to form transformed foci. Diminished transformation potential of transduced cells was a specific effect of the FAC cDNA since GM449 cells transduced with a rAAV vector not containing FAC retained marked susceptibility to SV40 transformation.

Base Sequence↗

Retroviral-mediated transduction of the fanconi anemia C complementing (FACC) gene in two murine transplantation models.

Fanconi anemia (FA) is a well-known genetic syndrome manifested by bone marrow failure, variable physical anomalies, and cancer susceptibility. This disorder is marked by genotypic and phenotypic heterogeneity and consists of four distinct complementation groups A, B, C, and D. The defective gene responsible for the C group of FA, FACC, was identified by cDNA complementation cloning, and we have recently proposed a trial of gene therapy for group C FA. No animal model yet exists for FA. Consequently, we have studied the effects of constitutive expression of human FACC in two murine transplantation models. In the first model, we demonstrated transduction of FACC to reconstituting stem cells of mutant W/WV mice. In the second model, we demonstrated transduction of FACC to hematopoietic cells transplanted to the bone marrows and spleens of non-myeloablated BALB/c mice. Our data suggest that retroviral-mediated transfer of the normal human FACC cDNA to hematopoietic progenitor and stem cells of mice is feasible and not associated with direct harmful effects to the hematopoietic organ.

Animals↗

Retroviral vector for gene therapy of X-linked severe combined immunodeficiency syndrome.

X-linked severe combined immunodeficiency syndrome (X-SCID) is a genetic disorder characterized by profound impairment of cell-mediated and humoral immunity. Affected children die of recurrent infections within 2 years of birth unless rescued by allogeneic transplantation from a suitable donor. Recently, the genetic defect responsible for X-linked SCID has been identified as a mutation in the gamma chain of the IL-2 receptor, a protein also shared by the IL-4 and IL-7 receptors and therefore now denoted the common gamma chain (gamma c). We report here the development of a high-titer amphotropic retroviral vector for transfer of gamma c. This vector was used to transfer a copy of the gamma c cDNA to murine 3T3 fibroblasts, CD34-enriched hematopoietic progenitor cells obtained from bone marrow and umbilical cord blood of normal donors, and to transplanted murine bone marrow progenitors. Murine 3T3 cells transduced by the retroviral vector were analyzed by Southern blot hybridization and Western transfer. Southern analysis confirmed the integration of unrearranged proviral DNA, and Western blot analysis demonstrated the expression of gamma c protein. CD34-enriched cells were infected with viral vectors bearing gamma c and grown in methylcellulose media. Individual colonies and pools of cells were analyzed 2 weeks later by polymerase chain reaction assay, which confirmed the proviral marking. The vector was also used to transfer a copy of the gamma c cDNA to murine bone marrow cells in a transplantation model. Infected marrow was transplanted into syngeneic Balb/c mice.(ABSTRACT TRUNCATED AT 250 WORDS)

3T3 Cells↗

Transduction of CD34-enriched human peripheral and umbilical cord blood progenitors using a retroviral vector with the Fanconi anemia group C gene.

BACKGROUND: Fanconi anemia (FA) is an autosomal recessive inherited form of bone marrow failure. FA cells are characterized by their extreme sensitivity to DNA cross-linking agents that cause DNA instability and cell death. Four genetic complementation groups for FA have been identified and the gene for the complementation C group (FACC) has been cloned. Genetic transfer of the FACC gene should provide a growth advantage in transduced hematopoietic cells. We have previously demonstrated efficient retroviral-mediated gene transduction and correction of FA(C) cell lines and peripheral blood-derived CD34+ progenitors from patients carrying mutant FACC alleles. In this report we sought to define the optimal conditions for transduction of CD34+ progenitors from mobilized peripheral blood and umbilical cord blood. METHODS: Peripheral blood hematopoietic progenitors were obtained by G-CSF mobilization followed by apheresis. Human fetal cord blood cells were obtained from full-term gestation deliveries. Cells were immunoselected for CD34 antigen expression and then incubated with recombinant retroviruses containing a selectable marker gene (neomycin). Recombinant colony stimulating factors were added to facilitate viral transduction. Cells were plated in methylcellulose and resulting hematopoietic colonies were isolated and analyzed by PCR. RESULTS: Transduction efficiency of peripheral blood progenitors (from normal individuals) using a retrovirus encoding the FACC cDNA was comparable to that of the retroviral producer G1Na.40 currently being used in clinical gene therapy marking studies. We extended our standard transduction protocol to analyze CD34+ and CD34+ CD38-subpopulations of progenitors derived from umbilical cord blood (from normal pregnancies). In addition, we tested whether FACC cDNA transduction could be improved by vector infection supported by autologous stroma. For FA(C) hematopoietic cell infection, vector supernatant transduction in the presence of recombinant human IL-3, IL-6, and SCF was found to be superior to transduction supported by autologous FA(C) patient stroma. CONCLUSIONS: We documented efficient retroviral transduction of umbilical cord blood and peripheral blood enriched for hematopoietic progenitor cells. These results suggest the feasibility of a clinical gene therapy protocol utilizing progenitor cells from both peripheral blood and umbilical cord blood.

Antigens, CD34↗

A functionally active retrovirus vector for gene therapy in Fanconi anemia group C.

Fanconi anemia (FA) is a rare genetic disorder characterized by progressive pancytopenia, congenital abnormalities, and a predisposition to malignancy. Recently, mutation in a novel gene named FACC (Fanconi anemia C complementing) has been identified as causing one type of FA. Here, we report successful functional complementation of four FA(C) cell lines using a retroviral vector to transfer a copy of the normal FACC gene. The hallmark of the FA cell phenotype is extreme sensitivity to cross-linking agents such as mitomycin C (MMC). Cell lines transduced by FACC viral vectors were distinguished by their ability to grow at concentrations of MMC several orders of magnitude higher than those concentrations inhibitory of parental controls. The genetically corrected cell lines were analyzed for susceptibility to MMC-induced chromosomal breakage and were found to have been normalized. These two different assays confirmed that our retroviral vectors were capable of transferring a functional FACC gene to lymphoid cell lines established from FA(C) patients. We next analyzed the ability of our viral vectors to functionally correct hematopoietic progenitor cells from a patient bearing a splice donor mutation. Progenitor cells were purified by an immunoaffinity column to enrich for cells with high CD34 expression. Similar to FA lymphoid cell lines, this patient's CD34-enriched cells were extremely sensitive to MMC. After infection of these progenitor cells with viral vectors bearing normal FACC, increased numbers of colonies formed both in the absence and presence of < or = 5 nmol/L MMC, but no colonies formed from uninfected cells, even in the absence of MMC. Polymerase chain amplification was used to confirm proviral DNA integration. Thus, retroviral vectors can be engineered to transfer a normal FACC gene to lymphoid cell lines and primary hematopoietic cells bearing four different FACC mutations. FA stem cells rescued by gene transduction should have a selective growth advantage within the hypoplastic FA marrow environment in vivo. These experiments suggest that gene therapy may be an effective treatment strategy for FA.

3T3 Cells↗

Phenotypic correction of Fanconi anemia in human hematopoietic cells with a recombinant adeno-associated virus vector.

Fanconi anemia (FA) is a recessive inherited disease characterized by defective DNA repair. FA cells are hypersensitive to DNA cross-linking agents that cause chromosomal instability and cell death. FA is manifested clinically by progressive pancytopenia, variable physical anomalies, and predisposition to malignancy. Four complementation groups have been identified, termed A, B, C, and D. The gene for the FA complementation group C, FACC, has been cloned. Expression of the FACC cDNA corrects the phenotypic defect of FA(C) cells, resulting in normalized cell growth in the presence of DNA cross-linking agents such as mitomycin C (MMC). Gene transfer of the FACC gene should provide a survival advantage to transduced hematopoietic cells, suggesting that FA might be an ideal candidate for gene therapy. We demonstrated efficient transduction, expression, and phenotypic correction in lymphoblastoid cell lines derived from FA (C) patients using a recombinant adeno-associated virus (rAAV) vector containing the FACC gene. Molecular characterization of the transduced FACC gene showed an intact unrearranged proviral genome with expression sufficient to normalize cell growth, cell cycle kinetics and chromosomal breakage in the presence of MMC. These observations were extended by testing rAAV transduction in hematopoietic progenitor cells. Peripheral blood CD34+ cells isolated from a FA (C) patient and transduced with rAAV/FACC virus yielded 5-10-fold more progenitor colonies than mock-infected cells, consistent with genetic "rescue" of corrected cells. This is the first demonstration of rAAV gene correction in primary human hematopoietic progenitor cells and has important implications for gene therapy of hematopoietic disorders, specifically FA.

Base Sequence↗

Single-copy transduction and expression of human gamma-globin in K562 erythroleukemia cells using recombinant adeno-associated virus vectors: the effect of mutations in NF-E2 and GATA-1 binding motifs within the hypersensitivity site 2 enhancer.

The use of recombinant adeno-associated virus (rAAV) vectors provides a new strategy to investigate the role of specific regulatory elements and trans-acting factors in globin gene expression. We linked hypersensitivity site 2 (HS2) from the locus control region (LCR) to a A gamma-globin gene (A gamma*) mutationally marked to allow its transcript to be distinguished from endogenous gamma-globin mRNA. The vector also contains the phosphotransferase gene that confers resistance to neomycin (NeoR). HS2 region mutations within the NF-E2 motifs prevented NF-E2 binding while preserving AP-1 binding. Another set in the GATA-1 motif prevented binding of the factor. Several NeoR K562 clones containing a single unrearranged RAAV genome with the A gamma* gene linked to the native HS2 core fragment (WT), mutant NF-E2 HS2 (mut-NFE2), mutant GATA-1 HS2 (mut-GATA1), or no HS [(-)HS] were identified. In uninduced K562 cells, mut-NFE2 clones expressed A gamma* mRNA at the same level as the WT clones, compared with a lack of A gamma* signal in the (-)HS2 clones. However, hemin induction of mut-NFE2 clones did not result in an increase in the A gamma* signal above the level seen in uninduced cells. Mut-GATA1 clones expressed the A gamma* mRNA at the same level as WT clones in both uninduced and induced cells. Thus, GATA-1 binding to this site does not appear to be required for the enhancing function of HS2 in this context. This single-copy rAAV transduction model is useful for evaluating the effects of specific mutations in regulatory elements on the transcription of linked genes.

Binding Sites↗

Gene therapy for human hemoglobinopathies.

Gene transfer of human globin genes into human pluripotent stem cells via viral vectors may soon be realized. The high level of globin gene expression believed to be required for the treatment of severe hemoglobinopathies necessitated the inclusion of cis-acting sequences (LCR). Retroviral vectors containing the LCR elements are prone to rearrangement, low titer, and poor expression. Inclusion of a "minilocus" containing four HS sites linked to a globin gene resulted in higher expression in transplanted mice, but rearrangement of the provirus still occurs, and it is unclear what significance these experiments have with regard to human marrow stem cell transduction. Recombinant AAV is among the newest of genetic transfer vectors. This once obscure virus possesses unique properties that distinguish it from all other vectors. Its major advantage is the lack of pathogenicity in humans. Wild-type AAV has the unusual ability to selectively integrate into the mammalian genome at a specific region, thus reducing the concern for genomic disruption and insertional mutagenesis. The ability of AAV to carry regulatory elements without interference from the viral template may enable greater control of transferred gene expression. Disadvantages currently include the inferior packaging systems which yield low numbers of recombinant virions which are contaminated with wild-type adenovirus. The small AAV genome that can be packaged (approximately 5 kb) rules out its use for transfer of larger genes. Recombinant AAV viruses do not appear to demonstrate the same site-specific genomic integration as wild-type viruses. Elucidation of the mechanism of site-specific integration should prove useful in the development of safe vectors for gene transfer as well as provide insight into the nature of DNA recombination in humans.

Dependovirus↗

Regulated high level expression of a human gamma-globin gene introduced into erythroid cells by an adeno-associated virus vector.

Gene therapy of severe hemoglobinopathies will require high-level expression of a transferred globin gene in erythroid cells. Distant regulatory elements flanking the beta-globin gene cluster, the locus control region, are needed for appropriate expression. We have explored the use of a human parvovirus, the adeno-associated virus (AAV), for globin gene transfer. The human A gamma-globin gene, linked to hypersensitivity site 2 from the locus control region of the beta-globin gene cluster, was subcloned into a plasmid (psub201) containing the AAV inverted terminal repeats. This construct was cotransfected with a helper plasmid containing trans-acting AAV genes into human 293 cells that had been infected with adenovirus. The recombinant AAV vector containing hypersensitivity site 2 stably introduced on average one or two unrearranged proviral copies into human K562 erythroleukemia cells. The transferred globin gene exhibited normal regulation upon hemin induction of erythroid maturation and was expressed at a level equivalent to a native chromosomal A gamma-globin gene.

Blotting, Southern↗

A trial of recombinant human interleukin-1 in patients with severe refractory aplastic anaemia.

We report here the effects of in vivo administration of recombinant interleukin-1 alpha (rIL-1 alpha) to patients with severe, idiopathic aplastic anaemia. Four patients who were refractory to immunosuppressive therapy and were not bone marrow transplantation candidates received daily doses of 0.03 microgram/kg and 0.10 microgram/kg intravenously as 5 d courses. No significant changes in either peripheral blood counts or bone marrow cellularity were observed at either dose during or following therapy. Two patients showed increased numbers of bone marrow progenitor colonies. Lymphocyte phenotyping demonstrated an elevated percentage of CD8+/DR+ activated suppressor T lymphocytes prior to therapy. After rIL-1 alpha administration, the percentage of CD8+/DR+ cells was reduced or returned to normal in all patients. Significant side-effects included fever, rigours, fatigue, headache and nausea. Transient hypotension was observed at both doses in all patients. These results suggest that while rIL-1 alpha can be safely administered, no significant haematologic improvement was observed in patients with severe aplastic anaemia.

Adolescent↗

Expression of stem cell inhibitor (SCI) gene in patients with bone marrow failure.

Stem cell inhibitor (SCI) has been shown to inhibit the proliferation of primitive progenitors. The inhibitor, a product of bone marrow macrophages, activated lymphocytes, and monocytes, is identical to macrophage inflammatory protein (MIP-1 alpha). We report homologous (SCI/hMIP-1 alpha) sequences in freshly isolated lymphocytes, monocytes, and granulocytes and have found that SCI mRNA can be induced in monocytes by lipopolysaccharide (LPS) and interleukins 1, 2, and 6. In contrast, interferon gamma (IFN-gamma) decreases the expression of SCI/hMIP-1 alpha. Although only a low level expression of SCI/hMIP-1 alpha mRNA can be detected in normal human bone marrow nucleated cells (NCBM), very significant increases in the levels of SCI/hMIP-1 alpha RNA transcripts are observed in NCBM from patients with aplastic anemia (AA) and myelodysplastic syndrome (MDS). These data suggest that the expression of SCI/hMIP-1 alpha in bone marrow may reflect dysregulated cytokine production and activation of the immune system that may possibly contribute to disease progression.

Anemia, Aplastic↗

Development of the superoxide-generating system during differentiation of the HL-60 human promyelocytic leukemia cell line.

Utilizing the induced differentiation of HL-60 promyelocytic leukemia cells as a model of myeloid maturation, we examined the development of the superoxide-generating system, focusing on NADPH oxidase activity, membrane depolarization, and cytochrome b content. NADPH oxidase activity, measured as NADPH-dependent superoxide production, increased with both spontaneous and N,N-dimethylformamide-induced differentiation. Activity in particulate fractions from induced HL-60 cells and human peripheral blood polymorphonuclear leukocytes was proportional to their relative rates of superoxide production, but activity from uninduced cells was surprisingly high: one-third that from induced cells, despite only 7% their rate of superoxide generation. NADPH oxidase activities in phagocytic vesicles from induced HL-60 cells and polymorphonuclear leukocytes were equal, indicating the equivalence of the enzyme system in active portions of their cell membranes. Separation by centrifugal elutriation of the HL-60 cell population into fractions of varying maturity confirmed the relationship of NADPH oxidase activity to advancing differentiation in both dimethylformamide-induced and spontaneously maturing cells. Membrane potential change, an early event related to activation of the oxidase, was followed by 3,3'-dipropylthiodicarbocyanine dye fluorescence. The depolarization response increased dramatically in both magnitude and initial rate of change during differentiation. The cells' cytochrome b content increased 3-fold with induction of differentiation, in proportion to the change in NADPH oxidase activity.

Cell Differentiation↗

Mechanism of arachidonic acid release in human polymorphonuclear leukocytes.

Previous studies have demonstrated that [3H]arachidonic acid is released from prelabeled human neutrophil phospholipids when the cells are stimulated by calcium ionophore A23187 or by opsonized zymosan. Neither lysophospholipid generated by phospholipase A2 activity, diacylglycerol nor monoacylglycerol produced via phospholipase C/diacylglycerol lipase action have been identified following neutrophil challenge. The inability to detect any intermediates during the release of arachidonate is due to either rapid reacylation of lysophospholipid or conversion of diacylglycerol (monoacylglycerol) to cellular acylglycerols. The addition of exogenous [14C]fatty acid at the time of challenge was employed to determine the involvement of either phospholipase A2 or phospholipase C activities. Neutrophil stimulation with calcium ionophore A23187 resulted in an incorporation of exogenous [14C]arachidonate into phosphatidylinositol and phosphatidylcholine, those phospholipids which specifically release arachidonate. When the saturated fatty acid, [14C]stearate, replaced [14C]arachidonate, very little [14C]fatty acid was incorporated into any of the phospholipid species. Lipid phosphorus measurements revealed no significant mass change in any phospholipid class following ionophore challenge. Production of [14C]phosphatidic acid was not detected, as would be expected if diacylglycerol kinase and de novo phospholipid metabolism were significantly involved.

Arachidonic Acid↗

Arachidonic acid metabolism in polymorphonuclear leukocytes from patients with chronic granulomatous disease.

The effect of the calcium ionophore A23187 on the release and metabolism of [3H]arachidonic acid was examined in normal polymorphonuclear leukocytes and those obtained from patients with chronic granulomatous disease. The ionophore A23187 which stimulates oxidative metabolism in normal polymorphonuclear leukocytes was ineffective in increasing oxidative metabolism (chemiluminescence) in polymorphonuclear leukocytes from patients with chronic granulomatous disease. However, the ionophore A23187 stimulated the release of [3H]arachidonic acid from chronic granulomatous disease neutrophil phospholipids and stimulated its metabolism into hydroxyeicosatetraenoic acids and leukotrienes.

Arachidonic Acid↗

Platelet activating factor. Stimulation of the lipoxygenase pathway in polymorphonuclear leukocytes by 1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphocholine.

1-O-Alkyl-2-O-acetyl-sn-glycero-3-phosphocholine (AAGPC) triggered the release of [3H]arachidonate but not [14C]stearate from cellular phospholipids in cytochalasin B-treated rabbit polymorphonuclear leukocytes. Concentrations of AAGPC up to 20 nM caused a dose-dependent release and subsequent metabolism of the released [3H]arachidonic acid. Most of the release of the [3H]arachidonate had taken place within the first 2 min of stimulation. Phosphatidylinositol and phosphatidylcholine served as the sources of [3H]arachidonate with about 50% of the label coming from each pool. Challenge of cytochalasin B-treated polymorphonuclear leukocytes with AAPGC led to the production of [3H]hydroxyeicosatetraenoic acids and [3H]dihydroxyeicosatetraenoic acids. No significant production of [3H]prostaglandins or [3H]thromboxanes was detected. AAGPC also caused a dose-dependent degranulation of cytochalasin B-treated rabbit polymorphonuclear leukocytes as shown by the release of beta-glucuronidase and lysozyme. Both the AAGPC-stimulated production of arachidonate metabolites and the degranulation response were blocked by eicosatetraynoic acid and non-dihydroguaiaretic acid at similar inhibitor concentrations. These findings suggest the bioactions of AAGPC on polymorphonuclear leukocytes may be mediated by the release of arachidonic acid and the production of mono- and dihydroxyeicosatetraenoic acids.

Animals↗