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Adenoviral-mediated gene transfer of the human lipoprotein lipase gene Ashbourne Excoffon, Katherine J. D.
Abstract
Lipoprotein lipase is a pivotal enzyme involved in the metabolism of circulating lipoproteins. Through the hydrolysis of the triglycerides (TG) in TG-rich particles, free fatty acids and glycerol are available for uptake by muscle, for energy, or adipose for storage. Patients with complete and partial LPL deficiency exhibit marked hypertriglyceridemia and altered lipoprotein metabolism. Gene therapy to deliver functional LPL to the circulation has been proposed in order to reduce the clinical morbidity and atherogenic risk due to this metabolic disorder. In vitro analysis of first generation recombinant adenoviral (Ad) vectors expressing the human LPL gene from an RSV promoter or a CMV promoter (Ad-LPL) revealed efficient infection and subsequent LPL expression in several cell lines. Delivery of Ad-LPL (RSV or CMV driven) to the liver of either normal mice or mice heterozygous for LPL deficiency results in an improved lipoprotein profile for at least 42 days and the correction of impaired fat load tolerance. Similarly, an Ad incorporating a common polymorphism that deletes the last two amino acids of LPL (Ser447Ter) results in an improved profile. Despite minimal hepatoxicity in these animals, the augmentation of LPL expression from natural sites, including muscle and adipose, was investigated using the CMV-driven Ad-LPL vector. After intra-adipose or intra-muscular Ad-LPL treatment via direct injection, expression within the adipose and muscle tissue compartments was significantly elevated until D14. Regardless of this over expression, no change in plasma LPL activity or TG levels was evident. Due to the neo-natal lethality associated with complete LPL deficiency in mice, a larger feline model of complete deficiency was explored. Complete correction in a cohort of homozygous LPL deficient cats was observed for 14 days before expression was extinguished, likely due to a vigorous immune response to both the adenovirus and the human LPL gene. In summary, the outcome effected by transferring the LPL gene to animal models, as well as somatic cells in tissue culture, have been defined for the first time. Evaluation of the systemic and tissue-specific efficiency, stability, potential toxicity and immunogenicty of adenoviral-mediated LPL gene expression has been delineated over the duration of these studies providing proof-of-principle towards LPL gene therapy. Although adenovirus is an efficient vector for gene delivery, future studies will evaluate alternative vector systems that display longer term expression and less immunogenicity, such as the adeno-associated virus.
Item Metadata
Title |
Adenoviral-mediated gene transfer of the human lipoprotein lipase gene
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2000
|
Description |
Lipoprotein lipase is a pivotal enzyme involved in the metabolism of circulating
lipoproteins. Through the hydrolysis of the triglycerides (TG) in TG-rich particles, free fatty
acids and glycerol are available for uptake by muscle, for energy, or adipose for storage.
Patients with complete and partial LPL deficiency exhibit marked hypertriglyceridemia and
altered lipoprotein metabolism. Gene therapy to deliver functional LPL to the circulation has
been proposed in order to reduce the clinical morbidity and atherogenic risk due to this
metabolic disorder.
In vitro analysis of first generation recombinant adenoviral (Ad) vectors expressing
the human LPL gene from an RSV promoter or a CMV promoter (Ad-LPL) revealed
efficient infection and subsequent LPL expression in several cell lines.
Delivery of Ad-LPL (RSV or CMV driven) to the liver of either normal mice or mice
heterozygous for LPL deficiency results in an improved lipoprotein profile for at least 42
days and the correction of impaired fat load tolerance. Similarly, an Ad incorporating a
common polymorphism that deletes the last two amino acids of LPL (Ser447Ter) results in
an improved profile.
Despite minimal hepatoxicity in these animals, the augmentation of LPL expression
from natural sites, including muscle and adipose, was investigated using the CMV-driven
Ad-LPL vector. After intra-adipose or intra-muscular Ad-LPL treatment via direct injection,
expression within the adipose and muscle tissue compartments was significantly elevated
until D14. Regardless of this over expression, no change in plasma LPL activity or TG levels
was evident.
Due to the neo-natal lethality associated with complete LPL deficiency in mice, a
larger feline model of complete deficiency was explored. Complete correction in a cohort of
homozygous LPL deficient cats was observed for 14 days before expression was
extinguished, likely due to a vigorous immune response to both the adenovirus and the
human LPL gene.
In summary, the outcome effected by transferring the LPL gene to animal models, as
well as somatic cells in tissue culture, have been defined for the first time. Evaluation of the
systemic and tissue-specific efficiency, stability, potential toxicity and immunogenicty of
adenoviral-mediated LPL gene expression has been delineated over the duration of these
studies providing proof-of-principle towards LPL gene therapy. Although adenovirus is an
efficient vector for gene delivery, future studies will evaluate alternative vector systems that
display longer term expression and less immunogenicity, such as the adeno-associated virus.
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Extent |
16848917 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-07-21
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0089746
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2000-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.