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ABSTRACT: We systematically compared human factor IX gene expression from a variety of plasmids containing different cis-regulatory sequences after transfection into different hepatocyte cell lines, or in vivo, after their injection into the livers of mice. Although there was a 1.5- to 2.0-fold variation in gene expression from cultured cells, a 65-fold variation was observed in the in vivo studies. We found that a plasmid containing the apolipoprotein E locus control region (HCR), human alpha1-antitrypsin (hAAT) promoter, hFIX minigene (hFIXmg) sequence including a portion of the first intron (intron A), 3'-untranslated region (3'-UTR), and a bovine growth hormone polyadenylation signal (bpA) produced the highest serum level of human factor IX, reaching 18 microg/ml (normal = 5 microg/ml) 1 day after injection. Although most of the plasmid DNAs resulted in transient gene expression, inclusion of an intron, a polyadenylation signal from either the 1.7-kb 3'-UTR or the 0.3-kb bpA, and the HCR resulted in persistent and therapeutic levels of hFIX gene expression, ranging from 0.5 to 2 microg/ml (10 to 40% of normal) for 225 days (length of experiment). These data underscore the importance of cis sequences for enhancing in vivo hepatic gene expression and reemphasize the lack of correlation of gene expression in tissue culture and in vivo studies.
Molecular Therapy 07/2000; 1(6):522-32. · 6.87 Impact Factor
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ABSTRACT: Recombinant adeno-associated virus vectors have been shown to safely transduce a number of tissues in preclinical animal studies. The level of gene transfer is sufficient to successfully treat a large number of medical disorders. Moreover, the long-term persistence of the vector sequences in animals makes it likely that this vector will be useful for genetic diseases requiring life-long therapy. This review outlines the biological principles of the vector, as well as its advantages and current limitations as it relates to use in hepatic gene therapy.
Seminars in Liver Disease 02/1999; 19(1):61-9. · 7.05 Impact Factor
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ABSTRACT: Recombinant retroviral vectors are attractive for in vivo gene transfer into the liver because they integrate into the host-cell genome, resulting in permanent gene expression. Gene-transfer efficiency can be improved by increasing the number of retroviral particles delivered to hepatocytes. For this purpose, we report a mouse model for continuous infusion into the portal circulation permitting large-volume vector administration, which will allow marked increase in gene-transfer efficiency. Continuous saline infusion was evaluated, using various parameters, and an infusion rate of 6 ml/24 h was found safe and well tolerated for at least 2 weeks. No significant changes in liver and kidney function and electrolyte balance were observed during the infusion. In addition to providing a valuable method for in vivo hepatic gene therapy, this model has a number of other potential applications, including mouse studies of hepatic tumor therapy, pharmacology, toxicology, and liver biology.
Laboratory animal science 09/1998; 48(4):379-83.
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ABSTRACT: Recombinant retroviral vectors are an attractive means of transferring genes into the liver because they integrate into the host cell genome and result in permanent gene expression. However, efficient in vivo gene transfer is limited by the requirement of active cell division for integration. Traditional approaches to induce liver proliferation have the disadvantage of inducing hepatocellular injury by delivery of toxins or by surgical partial hepatectomy. As a nontraumatic alternative, we show that exogenous hepatocyte growth factor (HGF) is a powerful and safe mitogen for the mature intact murine liver when delivered continuously into the portal vein. A 5-day infusion of human HGF (5 mg/kg/d) resulted in > 140% increase in relative liver mass, which returned to normal in 4 to 5 weeks. This clearly shows that an exogenous growth factor can induce robust liver proliferation in vivo. In addition, we show that the HGF-induced proliferation was independent of interleukin-6, an essential cytokine involved in liver regeneration after partial hepatectomy. When recombinant retroviral vectors were infused in combination with HGF, 30% of hepatocytes were stably transduced with no indication of hepatic injury or histopathology. These results show the ability to obtain a clinically relevant transduction efficiency with retroviral vectors in vivo without the prior induction of liver injury. The level of hepatic gene transfer achieved has the potential to be curative for a large number of genetic liver diseases.
Hepatology 09/1998; 28(3):707-16. · 11.66 Impact Factor
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ABSTRACT: Recombinant retroviral vectors represent an attractive means of transferring genes into the liver because they integrate in the host cell genome and result in permanent gene expression. However, efficient gene transfer is limited by the requirement of active cell division for integration. Surgical partial hepatectomy has been the traditional method of inducing hepatocellular proliferation, but this invasive approach would be difficult to justify in clinical gene therapy. As an alternative, we used a recombinant adenovirus expressing a nonsecreted form of urokinase plaminogen activator (Ad.PGKmuPA), which results in liver regeneration over a period of 8 days. When a high-titer retroviral vector was continuously infused into the portal vein of mice during this period of hepatocyte proliferation, 33.5% of hepatocytes were stably transduced. In addition, high-level expression of a secreted transgene reporter was sustained for at least 48 weeks (length of experiment). We investigated the influence of vector titer on the in vivo transduction efficiency in our system, and found that the total number of infectious retroviral particles delivered per target cell is a critical factor. The results presented here demonstrate the ability to obtain a high gene transfer efficiency and long-term gene expression in hepatocytes in vivo without the need for surgical hepatectomy. The two-vector system described here may be of clinical relevance, as the level of hepatic gene transfer achieved has potential to be curative for a large number of genetic liver diseases.
Human Gene Therapy 08/1998; 9(10):1449-56. · 4.22 Impact Factor
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Nature Genetics 06/1998; 19(1):13-5. · 35.53 Impact Factor
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R O Snyder,
C H Miao, G A Patijn,
S K Spratt,
O Danos,
D Nagy,
A M Gown,
B Winther,
L Meuse,
L K Cohen,
A R Thompson,
M A Kay
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ABSTRACT: Haemophilia B, or factor IX deficiency, is a X-linked recessive disorder that occurs in about one in 25,000 males, and severely affected people are at risk for spontaneous bleeding into numerous organs. Bleeding can be life-threatening or lead to chronic disabilities with haemophilic arthropathy. The severity of the bleeding tendency varies among patients and is related to the concentration of functional plasma factor IX. Patients with 5-30% of the normal factor IX have mild haemophilia that may not be recognized until adulthood or after heavy trauma or surgery. Therapy for acute bleeding consists of the transfusion of clotting-factor concentrates prepared from human blood and recombinant clotting factors that are currently in clinical trials. Both recombinant retroviral and adenoviral vectors have successfully transferred factor IX cDNA into the livers of dogs with haemophilia B. Recombinant retroviral-mediated gene transfer results in persistent yet subtherapeutic concentrations of factor IX and requires the stimulation of hepatocyte replication before vector administration. Recombinant adenoviral vectors can temporarily cure the coagulation defect in the canine haemophilia B model; however, an immune response directed against viral gene products made by the vector results in toxicity and limited gene expression. The use of recombinant adeno-associated virus (rAAV) vectors is promising because the vector contains no viral genes and can transduce non-dividing cells. The efficacy of in vivo transduction of non-dividing cells has been demonstrated in a wide variety of tissues. In this report, we describe the successful transduction of the liver in vivo using r-AAV vectors delivered as a single administration to mice and demonstrate that persistent, curative concentrations of functional human factor IX can be achieved using wild-type-free and adenovirus-free rAAV vectors. This demonstrates the potential of treating haemophilia B by gene therapy at the natural site of factor IX production.
Nature Genetics 08/1997; 16(3):270-6. · 35.53 Impact Factor
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ABSTRACT: Hepatocyte transplantation is a potential form of therapy for patients with genetic hepatodeficiency disorders. Unfortunately, hepatocellular transplantation has been limited because of the relatively low numbers of donor cells that can ultimately take up residence in the host liver. To give the donor cells a proliferative stimulus, a recombinant adenovirus vector that expresses a nonsecreted urokinase (urokinase-type plasminogen activator) was transduced into the livers of recipient animals before transplantation. Because urokinase production in hepatocytes causes the slow turnover of hepatocytes, 2 days after adenovirus-mediated gene transfer into the livers of recipient mice, 2 x 10(6) congenic donor cells tagged with beta-galactosidase (beta-Gal) reporter were implanted via the portal vein. As a result, on average, 8.6% of the recipient hepatocytes in the livers were derived from donor cells--a 20-fold increase compared with control animals in which no proliferative stimulus was present.
Hepatology 05/1997; 25(4):884-8. · 11.66 Impact Factor
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ABSTRACT: Recombinant adenoviruses have received much attention as a potential vector for gene therapy because of their ability to transduce many cell types with high efficiencies in vivo. After intravenous infusion, the majority of the vector is found in hepatocytes, but vector DNA is found to varying degrees in other tissues. In an attempt to restrict adenovirus-mediated gene transfer to the liver, we developed a microsurgical method that allowed for vector administration directly into the biliary tract of a mouse. We demonstrate that gene transfer was 4- to 10-fold more restricted to the liver after biliary tract infusion than after intravascular infusion. Intravascular infusion of recombinant adenovirus elicits a powerful immune response that limits gene expression and the ability to readminister the vector. Biliary infusion resulted in a slightly lesser immune response as determined by the lower neutralizing antibody titers directed against the vector compared with animals treated by intravascular infusion. There was no difference in the persistence of gene expression, suggesting a similar cell-mediated immune response against the vector containing cells in animals administered vector by either method. As future-generation adenovirus vectors that are safer and less immunogenic become available, the more liver specific gene transfer via the biliary tract may offer advantages over intravenous infusion for hepatic gene therapy.
Human Gene Therapy 10/1996; 7(14):1693-9. · 4.22 Impact Factor
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ABSTRACT: Graft-infiltrating cells can be cultured from fresh endomyocardial biopsies (EMB) taken after heart transplantation to determine their growth patterns, phenotypic composition, and functional characteristics for clinical or scientific purposes. In this study we investigated whether graft-infiltrating cells can also be cultured successfully after cryopreservation of these EMB. Three different cryopreservation methods were used. One method gave successful growth in 100% of the cases (n = 6): The biopsy fragments were preincubated in 10% vol/vol dimethyl sulfoxide during 5 min at 0 degree C, frozen to -70 degrees C at approximately 1 degree C per minute, and subsequently immersed and stored in liquid nitrogen. Thawing was performed rapidly in water at 37 degrees C. In addition, the effect of cryopreservation on cell surface phenotype and donor-specific cytotoxicity of these graft-infiltrating cells was analyzed. When compared to cultures of nonfrozen control biopsies, both qualities remained constant in most cases, although a variation in CD4+/CD8+ cell ratio was observed in 33% of these cultures. However, when nonfrozen fragments of size-matched biopsies were cultured separately, a similar variation in phenotype was noted, indicating that this phenomenon can be attributed to sampling variation and not to the cryopreservation procedure. The present findings suggest that it is no longer required to culture fresh (nonfrozen) post-transplant EMB to propagate graft-infiltrating cells: Culturing can be limited to cryopreserved EMB that are selected retrospectively, depending on actual clinical or scientific interests. Besides greatly facilitating the long-term monitoring of heart transplant recipients, this also means a substantial decrease in cost and work load for laboratories involved in heart transplantation.
Cryobiology 09/1996; 33(4):465-71. · 2.06 Impact Factor
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ABSTRACT: Human immunodeficiency virus (HIV) can be transmitted by solid organ and some forms of tissue transplantation. Although routine screening of organ and tissue donors for anti-HIV antibodies was implemented in most Western European countries and North America in 1985, several recent case reports indicate that a definite, albeit very small, risk of HIV transmission still remains. The screening tests that are currently used cannot rule out a false-negative test result occurring during the window period. Moreover, massive transfusion of the donor during the donor procedure may result in an undetectable anti-HIV antibody titer (by dilution of donor blood) that consequently leads to a false-negative test result. These risks of HIV transmission via transplantation and important issues in HIV testing are discussed in detail. Furthermore, several recommendations for the prevention of transmission and a protocol for HIV testing for both organ and tissue donation are presented. These may serve as intermediary guidelines until official ones, such as already exist for blood donation, are defined by the transplantation communities. The exclusion of donors whose behavior may place potential recipients at risk for HIV infection is essential. A thorough heteroanamnesis of the donor's next of kin during the donor procedure should provide sufficient information about donor history to enable a decision to be made in this respect. Special attention is given to the question of whether the existing donor selection criteria for blood donation should be applied in a similar way to organ donation since the strict application of selection criteria may limit the number of available donor organs.(ABSTRACT TRUNCATED AT 250 WORDS)
Transplant International 06/1993; 6(3):165-72. · 2.92 Impact Factor
