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906. High Efficiency Hepatic Transduction with Minimal Toxicity Following “Hydrodynamic” Injection of HDAd into Nonhuman Primates
INBORN ERRORS OF METABOLISM: LIVER AND PANCREATIC DISEASES containing a potent expression cassette with a vector expressing the transgene at a lower potency. Our results suggest that vector expressing greater OTC levels allows correction of orotic acid overproduction with lower vector doses. Moreover, we were able to achieve phenotypic correction with a dose (1x1012vp/kg) which is significantly lower than those previously reported for correction with either first-generation or HDAd vectors. Vectors containing the expression cassette used in this study combined with other strategies for improving HDAd therapeutic index will likely permit application of these vectors for the treatment of OTC deficiency as well as other urea cycle disorders. There likely is a limit to the benefit of overexpressing OTC in a smaller population of deficient cells given the magnitude of nitrogen transfer that must be handled by the liver on a daily basis. At the same time, we will need to evaluate potential adverse consequences of over-expression of these enzymes.
904. High Efficiency Hepatic Transduction and Long-Term Transgene Expression by Delivering Helper-Dependent Adenoviral Vectors into the Surgically Isolated Liver of Nonhuman Primates Nicola Brunetti-Pierri,1 Thomas Ng,2 David Iannitti,2 William Cioffi,2 Donna Palmer,1 Arthur Beaudet,1 Milton Finegold,3 Dee Carey,4 Philip Ng.1 1 Department of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX; 2Department of Surgery, Brown Medical School, Providence, RI; 3Department of Pathology, Baylor College of Medicine, Houston, TX; 4Southwest Foundation for Biomedical Research, San Antonio, TX. Helper-dependent adenoviral vectors (HDAd) are attractive vectors for liver-directed gene therapy because they can mediate long-term, high level transgene expression with no long-term toxicity. However, as a consequence of a threshold effect, high vector doses are required to achieve efficient hepatic transduction by peripheral intravenous injection which unfortunately results in a dosedependent activation of the innate inflammatory response. Clearly strategies to overcome the threshold to efficient hepatic transduction are needed to improve the therapeutic index of HDAd. We hypothesized that this obstacle could be surmounted by delivering the vector exclusively to the liver. To test this hypothesis, we have injected HDAd directly into the surgically isolated liver via the portal vein in nonhuman primates. Total hepatic isolation was achieved by occluding hepatic inflow from the portal vein and hepatic artery and by occluding hepatic venous outflow at the inferior vena cava. Prior to total hepatic isolation, saline was infused into the portal vein to flush blood out of the liver. The vector was then injected directly into the liver via the portal vein and allowed to dwell for 30 minutes, following which unabsorbed vector was flushed out via a catheter placed in the vena cava to minimize systemic vector dissemination. Our results revealed that significantly higher hepatic transduction efficiencies can be achieved with relatively low vector doses compared to peripheral intravenous injection. Importantly, stable, high levels of transgene expression were observed for up to one year with no long-term toxicity. This approach may increase the safety and efficacy of HDAd-mediated, liver-directed gene therapy by minimizing the dose required to achieve efficient hepatic transduction and by minimizing systemic vector dissemination.
S350
905. Hydrodynamic Injection of HelperDependent Adenoviral Vectors Increases Liver Transduction Efficiency and Decreases Acute Inflammatory Response Nicola Brunetti-Pierri,1 Viraj Mane,1 Donna Palmer,1 Arthur Beaudet,1 Milton Finegold,2 Philip Ng.1 1 Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX; 2Department of Pathology, Baylor College of Medicine, Houston, TX. Hydrodynamic injection of helper-dependent adenoviral vectors (HDAd) in mice results in increased hepatic transduction resulting in higher levels of long-term transgene expression compared to conventional injection. Furthermore, hydrodynamic injection resulted in reduced splenic and pulmonary transduction and reduced serum levels of the proinflammatory cytokines IL-6 and IL-12. Interestingly, hydrodynamic injection does not appear to alter Kupffer cell uptake of the vector compared to conventional injection. Taken together, these results strongly suggest that hepatic transduction by HDAd, at least alone, does not necessarily provoke a severe innate inflammatory response, but that systemic vector dissemination may play a major role in the severity of the innate inflammatory response. These results further suggest that the safety and efficacy of HDAd-mediated, liver-directed gene therapy may be improved if the vector could be preferentially, if not exclusively, targeted to hepatocytes.
906. High Efficiency Hepatic Transduction with Minimal Toxicity Following “Hydrodynamic” Injection of HDAd into Nonhuman Primates Nicola Brunetti-Pierri,1 Charles Mullins,2 Donna Palmer,1 Milton Finegold,3 Arthur Beaudet,1 Karen Rice,4 Dee Carey,4 Philip Ng.1 1 Department of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX; 2Department of Pediatics Cardiology, Baylor College of Medicine, Houston, TX; 3Department of Pathology, Baylor College of Medicine, Houston, TX; 4Southwest Foundation for Biomedical Research, San Antonio, TX. Helper-dependent adenoviral vectors (HDAd) are attractive vectors for liver-directed gene therapy because they can mediate sustained, high level transgene expression with no long-term toxicity. However, as a consequence of a threshold effect, high vector doses are required to achieve efficient hepatic transduction by peripheral intravenous injection which unfortunately results in a dosedependent activation of the innate inflammatory response. Clearly strategies to overcome the threshold to efficient hepatic transduction are needed to improve the therapeutic index of HDAd. We have recently shown that systemic hydrodynamic injection of HDAd into mice resulted in exceedingly high levels of hepatic transduction and reduction in both systemic vector dissemination and acute proinflammatory cytokines compared to conventional injection. Hydrodynamic injection offers a method of dramatically increasing the therapeutic index of HDAd but, unfortunately, cannot be applied to larger animals due to the large injection volume. Therefore, we have developed a minimally invasive method to mimic hydrodynamic injection in nonhuman primates which does not require injection of large volumes. This method involves the use of balloon occlusion catheters percutaneously positioned in the vena cava to transiently obstruct hepatic venous outflow to increase the intrahepatic pressure prior to simple peripheral intravenous injection of HDAd in a small volume. We demonstrate in nonhuman primates that this novel method of vector delivery results in an exceedingly high and unprecedented level of hepatic transduction with low vector doses resulting in stable, long-term transgene expression. This was accompanied by reduced systemic vector dissemination and minimal, transient elevations of proinflammatory cytokines. Despite the Molecular Therapy Volume 11, Supplement 1, May 2005 Copyright The American Society of Gene Therapy
INBORN ERRORS OF METABOLISM: LIVER AND PANCREATIC DISEASES relatively high intrahepatic pressures achieved, there was minimal evidence of liver injury; no histological abnormalities were observed and only minimal and transient elevation of AST and ALT were noted. The procedure itself was uneventful and very well tolerated with no clinical manifestations of acute or chronic toxicities. This novel method of delivering HDAd is simple, minimally invasive, and clinically relevant since it increases the therapeutic index of HDAd for liver-directed gene therapy by allowing high efficiency hepatic transduction with low vector doses and with negligible acute or chronic toxicities.
907. Gene Therapy for Genetic Lipoprotein Lipase (LPL) Deficiency; an Update Jaap Rip,1 Melchior C. Nierman,1 Jeroen A. Sierts,1 Colin J. Ross,2 Michael R. Hayden,2 Albertine de Jong,3 Paul Dijkhuizen,3 Wim Hermens,3 Jaap Twisk,3 John J. Kastelein,1 Jan Albert Kuivenhoven,1 Janneke M. Meulenberg.3 1 Department of Vascular Medicine, Academic Medical Centre, Amsterdam, Netherlands; 2Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, BC, Canada; 3Amsterdam Molecular Therapeutics, Amsterdam, Netherlands. Lipoprotein lipase (LPL) deficiency cannot be effectively treated and causes severe hypertriglyceridemia and pancreatitis. We have reported that adeno-associated virus serotype 1 (AAV1) based gene therapy normalizes triglyceride levels in LPL deficient mice and cats. The current study evaluates safety and biodistribution of the same vector, AAV1-LPLS447X, and addresses clinical application. Toxicological analysis after intramuscular administration of AAV1LPLS447X (1E11-1E13 gc/kg) in murine dose-escalation studies did not reveal clinical or hematological changes. Shortly after administration (7 days), vector DNA was found in injected muscle, draining lymph nodes, and filtering organs while spread to reproductive organs was limited. 28 and 90 days post injection, vector DNA levels dissipated in all tissues except for injected muscle and lymph nodes. Furthermore, we studied 6 LPL deficient patients to assess eligibility for a first clinical trial. All presented with absence of LPL catalytic activity but LPL protein levels were 19-103% of normal. Infection of patient’s myoblasts with AAV1-LPLS447X resulted in the secretion of catalytically active LPL in all cases. The efficacy and safety data obtained so far support the initiation of a clinical trial to test this vector in LPL deficient patients.
908. Evaluation of the Sleeping Beauty Transposon System in OTC Deficient Spf-Ash Mice: A Non-Viral Approach to a Cell Autonomous Metabolic Disease Andy Wilber,1 Joel Frandsen,1 Hiroki Morizono,2 Mendel Tuchman,2 R. Scott McIvor.1 1 GCD, University of Minnesota, Minneapolis, MN; 2Children’s National Medical Center, George Washington University, Washington, DC. In humans, ornithine transcarbamylase (OTC) deficiency is the most common error of the urea cycle. The limited potential of medical procedures for life-long correction suggests liver-directed gene therapy as an alternative. Some 15 years of research using viral vectors in OTC deficient mice generated 1 report of long-term correction using helper-dependent adenovirus (Ad) to express a stabilized human OTC gene. However, the failure of a recombinant Ad clinical trial argues that non-viral vectors may be the more appropriate choice for molecular therapy of this disorder. The Sleeping Beauty (SB) transposon has been demonstrated to mediate insertion and
Molecular Therapy Volume 11, Supplement 1, May 2005 Copyright The American Society of Gene Therapy
expression of secreted or advantageous gene products in hepatocytes. Here, we present the first application of a plasmid system for therapy of a cell autonomous disorder. Localization of OTC enzyme to the mitochondria suggests a potential limitation with respect to the gene transfer efficiency that can be achieved by non-viral vectors. To address this issue, we studied the delivery of cis-acting transposons by evaluating the effect of DNA dose on stable gene expression using in vivo bioluminescent imaging (IVI) to monitor luciferase (luc) activity after infusion of a CAGS-regulated luc transposon with a ubiquitinregulated SB transposase (pT2/CL//UbSB) into C57BL/6 mice. Dose response experiments comparing 2, 20, and 200 µg of pT2/CL// UbSB showed the highest levels of persistent luc activity resulting from the 2 µg dose. We conducted studies using transposons encoding fluorescent proteins and luc on the same transcript, in cis with a ubiquitinregulated transposase (pKT2/CFIL//UbSb) to correlate the number of fluorescent cells in liver sections or hepatocyte suspensions with transient and stable luc activity measured by IVI. Stable in vivo luc activity of 7x107 photons/sec was observed following a single injection of (pKT2/CFIL//UbSB) and defined transient expression to 1 in 10 cells and stable expression to 1 in 200 cells. Finally, OTC deficient mice were infused with bifunctional transposons with the mouse OTC cDNA (pKT2/COIL//UbSB), monitoring in vivo luc activity and urinary orotic acid levels as a measure of OTC expression. OTC deficient mice infused with pKT2/ COIL//UbSB mimicked luc levels achieved in mice administered fluorescent protein/luc transposons, indicating similar levels of transcription. OTC activity assayed in liver extracts from deficient mice infused with OTC/luc transposons was on average 100% higher after 2 days compared to uninjected controls, verifying presence of the OTC enzyme. Additional mice (n=5) infused with OTC/luc transposon +/- transposase exhibited maintenance of in vivo luc activity in animals receiving the transposase. These results suggest a correlation between in vivo luc activity and the number of genetically modified hepatocytes. In addition, these results are encouraging with respect to anticipated use of the SB transposon for treatment of diseases that do not benefit from a secreted or selective gene product, thus encompassing a wide range of genetic disorders. R. Scott McIvor has a financial interest in Discovery Genomics, Incorporated.
909. Sustained Correction of Glycogen Storage Disease Type II by rAAV1 Vector-Mediated Gene Therapy Kerry O. Cresawn,1 Cathryn S. Mah,1,2 Thomas J. Fraites, Jr.,1 Melissa A. Lewis,1 Irene Zolotukhin,2 Barry J. Byrne.1,2 1 Pediatrics and Powell Gene Therapy Center, University of Florida, Gainesville, FL; 2Cellular and Molecular Therapy, University of Florida, Gainesville, FL. Glycogen storage disease type II (GSDII), is a lysosomal storage disease caused by a partial to complete deficiency in the lysosomal hydrolase, acid α-glucosidase (GAA). From gestation, affected individuals store glycogen in their lysosomal compartments, resulting in severe hypertrophic cardiomyopathy and respiratory insufficiency. Previous studies with intrahepatic and intramuscular delivery of recombinant adeno-associated viral (rAAV) vectors to GSDII mice resulted in a variable anti-GAA immune response and insufficient levels of circulating protein in immune-responsive mice. In this study, we evaluated the potential for intravenously delivered rAAV vectors to correct the biochemical, histological and functional phenotype in GSDII mice over a sustained period of time. Neonatal GSDII mice were intravenously administered 5 x 1010 particles of rAAV serotype 1 vector encoding human GAA under control of the S351
904. High Efficiency Hepatic Transduction and Long-Term Transgene Expression by Delivering Helper-Dependent Adenoviral Vectors into the Surgically Isolated Liver of Nonhuman Primates Nicola Brunetti-Pierri,1 Thomas Ng,2 David Iannitti,2 William Cioffi,2 Donna Palmer,1 Arthur Beaudet,1 Milton Finegold,3 Dee Carey,4 Philip Ng.1 1 Department of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX; 2Department of Surgery, Brown Medical School, Providence, RI; 3Department of Pathology, Baylor College of Medicine, Houston, TX; 4Southwest Foundation for Biomedical Research, San Antonio, TX. Helper-dependent adenoviral vectors (HDAd) are attractive vectors for liver-directed gene therapy because they can mediate long-term, high level transgene expression with no long-term toxicity. However, as a consequence of a threshold effect, high vector doses are required to achieve efficient hepatic transduction by peripheral intravenous injection which unfortunately results in a dosedependent activation of the innate inflammatory response. Clearly strategies to overcome the threshold to efficient hepatic transduction are needed to improve the therapeutic index of HDAd. We hypothesized that this obstacle could be surmounted by delivering the vector exclusively to the liver. To test this hypothesis, we have injected HDAd directly into the surgically isolated liver via the portal vein in nonhuman primates. Total hepatic isolation was achieved by occluding hepatic inflow from the portal vein and hepatic artery and by occluding hepatic venous outflow at the inferior vena cava. Prior to total hepatic isolation, saline was infused into the portal vein to flush blood out of the liver. The vector was then injected directly into the liver via the portal vein and allowed to dwell for 30 minutes, following which unabsorbed vector was flushed out via a catheter placed in the vena cava to minimize systemic vector dissemination. Our results revealed that significantly higher hepatic transduction efficiencies can be achieved with relatively low vector doses compared to peripheral intravenous injection. Importantly, stable, high levels of transgene expression were observed for up to one year with no long-term toxicity. This approach may increase the safety and efficacy of HDAd-mediated, liver-directed gene therapy by minimizing the dose required to achieve efficient hepatic transduction and by minimizing systemic vector dissemination.
S350
905. Hydrodynamic Injection of HelperDependent Adenoviral Vectors Increases Liver Transduction Efficiency and Decreases Acute Inflammatory Response Nicola Brunetti-Pierri,1 Viraj Mane,1 Donna Palmer,1 Arthur Beaudet,1 Milton Finegold,2 Philip Ng.1 1 Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX; 2Department of Pathology, Baylor College of Medicine, Houston, TX. Hydrodynamic injection of helper-dependent adenoviral vectors (HDAd) in mice results in increased hepatic transduction resulting in higher levels of long-term transgene expression compared to conventional injection. Furthermore, hydrodynamic injection resulted in reduced splenic and pulmonary transduction and reduced serum levels of the proinflammatory cytokines IL-6 and IL-12. Interestingly, hydrodynamic injection does not appear to alter Kupffer cell uptake of the vector compared to conventional injection. Taken together, these results strongly suggest that hepatic transduction by HDAd, at least alone, does not necessarily provoke a severe innate inflammatory response, but that systemic vector dissemination may play a major role in the severity of the innate inflammatory response. These results further suggest that the safety and efficacy of HDAd-mediated, liver-directed gene therapy may be improved if the vector could be preferentially, if not exclusively, targeted to hepatocytes.
906. High Efficiency Hepatic Transduction with Minimal Toxicity Following “Hydrodynamic” Injection of HDAd into Nonhuman Primates Nicola Brunetti-Pierri,1 Charles Mullins,2 Donna Palmer,1 Milton Finegold,3 Arthur Beaudet,1 Karen Rice,4 Dee Carey,4 Philip Ng.1 1 Department of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX; 2Department of Pediatics Cardiology, Baylor College of Medicine, Houston, TX; 3Department of Pathology, Baylor College of Medicine, Houston, TX; 4Southwest Foundation for Biomedical Research, San Antonio, TX. Helper-dependent adenoviral vectors (HDAd) are attractive vectors for liver-directed gene therapy because they can mediate sustained, high level transgene expression with no long-term toxicity. However, as a consequence of a threshold effect, high vector doses are required to achieve efficient hepatic transduction by peripheral intravenous injection which unfortunately results in a dosedependent activation of the innate inflammatory response. Clearly strategies to overcome the threshold to efficient hepatic transduction are needed to improve the therapeutic index of HDAd. We have recently shown that systemic hydrodynamic injection of HDAd into mice resulted in exceedingly high levels of hepatic transduction and reduction in both systemic vector dissemination and acute proinflammatory cytokines compared to conventional injection. Hydrodynamic injection offers a method of dramatically increasing the therapeutic index of HDAd but, unfortunately, cannot be applied to larger animals due to the large injection volume. Therefore, we have developed a minimally invasive method to mimic hydrodynamic injection in nonhuman primates which does not require injection of large volumes. This method involves the use of balloon occlusion catheters percutaneously positioned in the vena cava to transiently obstruct hepatic venous outflow to increase the intrahepatic pressure prior to simple peripheral intravenous injection of HDAd in a small volume. We demonstrate in nonhuman primates that this novel method of vector delivery results in an exceedingly high and unprecedented level of hepatic transduction with low vector doses resulting in stable, long-term transgene expression. This was accompanied by reduced systemic vector dissemination and minimal, transient elevations of proinflammatory cytokines. Despite the Molecular Therapy Volume 11, Supplement 1, May 2005 Copyright The American Society of Gene Therapy
INBORN ERRORS OF METABOLISM: LIVER AND PANCREATIC DISEASES relatively high intrahepatic pressures achieved, there was minimal evidence of liver injury; no histological abnormalities were observed and only minimal and transient elevation of AST and ALT were noted. The procedure itself was uneventful and very well tolerated with no clinical manifestations of acute or chronic toxicities. This novel method of delivering HDAd is simple, minimally invasive, and clinically relevant since it increases the therapeutic index of HDAd for liver-directed gene therapy by allowing high efficiency hepatic transduction with low vector doses and with negligible acute or chronic toxicities.
907. Gene Therapy for Genetic Lipoprotein Lipase (LPL) Deficiency; an Update Jaap Rip,1 Melchior C. Nierman,1 Jeroen A. Sierts,1 Colin J. Ross,2 Michael R. Hayden,2 Albertine de Jong,3 Paul Dijkhuizen,3 Wim Hermens,3 Jaap Twisk,3 John J. Kastelein,1 Jan Albert Kuivenhoven,1 Janneke M. Meulenberg.3 1 Department of Vascular Medicine, Academic Medical Centre, Amsterdam, Netherlands; 2Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, BC, Canada; 3Amsterdam Molecular Therapeutics, Amsterdam, Netherlands. Lipoprotein lipase (LPL) deficiency cannot be effectively treated and causes severe hypertriglyceridemia and pancreatitis. We have reported that adeno-associated virus serotype 1 (AAV1) based gene therapy normalizes triglyceride levels in LPL deficient mice and cats. The current study evaluates safety and biodistribution of the same vector, AAV1-LPLS447X, and addresses clinical application. Toxicological analysis after intramuscular administration of AAV1LPLS447X (1E11-1E13 gc/kg) in murine dose-escalation studies did not reveal clinical or hematological changes. Shortly after administration (7 days), vector DNA was found in injected muscle, draining lymph nodes, and filtering organs while spread to reproductive organs was limited. 28 and 90 days post injection, vector DNA levels dissipated in all tissues except for injected muscle and lymph nodes. Furthermore, we studied 6 LPL deficient patients to assess eligibility for a first clinical trial. All presented with absence of LPL catalytic activity but LPL protein levels were 19-103% of normal. Infection of patient’s myoblasts with AAV1-LPLS447X resulted in the secretion of catalytically active LPL in all cases. The efficacy and safety data obtained so far support the initiation of a clinical trial to test this vector in LPL deficient patients.
908. Evaluation of the Sleeping Beauty Transposon System in OTC Deficient Spf-Ash Mice: A Non-Viral Approach to a Cell Autonomous Metabolic Disease Andy Wilber,1 Joel Frandsen,1 Hiroki Morizono,2 Mendel Tuchman,2 R. Scott McIvor.1 1 GCD, University of Minnesota, Minneapolis, MN; 2Children’s National Medical Center, George Washington University, Washington, DC. In humans, ornithine transcarbamylase (OTC) deficiency is the most common error of the urea cycle. The limited potential of medical procedures for life-long correction suggests liver-directed gene therapy as an alternative. Some 15 years of research using viral vectors in OTC deficient mice generated 1 report of long-term correction using helper-dependent adenovirus (Ad) to express a stabilized human OTC gene. However, the failure of a recombinant Ad clinical trial argues that non-viral vectors may be the more appropriate choice for molecular therapy of this disorder. The Sleeping Beauty (SB) transposon has been demonstrated to mediate insertion and
Molecular Therapy Volume 11, Supplement 1, May 2005 Copyright The American Society of Gene Therapy
expression of secreted or advantageous gene products in hepatocytes. Here, we present the first application of a plasmid system for therapy of a cell autonomous disorder. Localization of OTC enzyme to the mitochondria suggests a potential limitation with respect to the gene transfer efficiency that can be achieved by non-viral vectors. To address this issue, we studied the delivery of cis-acting transposons by evaluating the effect of DNA dose on stable gene expression using in vivo bioluminescent imaging (IVI) to monitor luciferase (luc) activity after infusion of a CAGS-regulated luc transposon with a ubiquitinregulated SB transposase (pT2/CL//UbSB) into C57BL/6 mice. Dose response experiments comparing 2, 20, and 200 µg of pT2/CL// UbSB showed the highest levels of persistent luc activity resulting from the 2 µg dose. We conducted studies using transposons encoding fluorescent proteins and luc on the same transcript, in cis with a ubiquitinregulated transposase (pKT2/CFIL//UbSb) to correlate the number of fluorescent cells in liver sections or hepatocyte suspensions with transient and stable luc activity measured by IVI. Stable in vivo luc activity of 7x107 photons/sec was observed following a single injection of (pKT2/CFIL//UbSB) and defined transient expression to 1 in 10 cells and stable expression to 1 in 200 cells. Finally, OTC deficient mice were infused with bifunctional transposons with the mouse OTC cDNA (pKT2/COIL//UbSB), monitoring in vivo luc activity and urinary orotic acid levels as a measure of OTC expression. OTC deficient mice infused with pKT2/ COIL//UbSB mimicked luc levels achieved in mice administered fluorescent protein/luc transposons, indicating similar levels of transcription. OTC activity assayed in liver extracts from deficient mice infused with OTC/luc transposons was on average 100% higher after 2 days compared to uninjected controls, verifying presence of the OTC enzyme. Additional mice (n=5) infused with OTC/luc transposon +/- transposase exhibited maintenance of in vivo luc activity in animals receiving the transposase. These results suggest a correlation between in vivo luc activity and the number of genetically modified hepatocytes. In addition, these results are encouraging with respect to anticipated use of the SB transposon for treatment of diseases that do not benefit from a secreted or selective gene product, thus encompassing a wide range of genetic disorders. R. Scott McIvor has a financial interest in Discovery Genomics, Incorporated.
909. Sustained Correction of Glycogen Storage Disease Type II by rAAV1 Vector-Mediated Gene Therapy Kerry O. Cresawn,1 Cathryn S. Mah,1,2 Thomas J. Fraites, Jr.,1 Melissa A. Lewis,1 Irene Zolotukhin,2 Barry J. Byrne.1,2 1 Pediatrics and Powell Gene Therapy Center, University of Florida, Gainesville, FL; 2Cellular and Molecular Therapy, University of Florida, Gainesville, FL. Glycogen storage disease type II (GSDII), is a lysosomal storage disease caused by a partial to complete deficiency in the lysosomal hydrolase, acid α-glucosidase (GAA). From gestation, affected individuals store glycogen in their lysosomal compartments, resulting in severe hypertrophic cardiomyopathy and respiratory insufficiency. Previous studies with intrahepatic and intramuscular delivery of recombinant adeno-associated viral (rAAV) vectors to GSDII mice resulted in a variable anti-GAA immune response and insufficient levels of circulating protein in immune-responsive mice. In this study, we evaluated the potential for intravenously delivered rAAV vectors to correct the biochemical, histological and functional phenotype in GSDII mice over a sustained period of time. Neonatal GSDII mice were intravenously administered 5 x 1010 particles of rAAV serotype 1 vector encoding human GAA under control of the S351