Gene Therapy in Tissue-Engineered Blood Vessels

Cardiovascular disease is the leading cause of morbidity and mortality in Western society. More than 1 million arterial bypass procedures are performed annually in the United States, where either autologous veins or synthetic grafts are used to replace arteries in the coronary or peripheral circulation. Tissue engineering of blood vessels from autologous cells has the potential to produce biological grafts for use in bypass surgery. Ex vivo development of vascular grafts also provides an ideal target of site-specific gene therapy to optimize the physiology of the developing conduit, and for the possible delivery of other therapeutic genes to a vascular bed of interest. In this article, we demonstrate that by using a novel retroviral gene delivery system, a target gene of interest can be specifically delivered to the endothelial cells of a developing engineered vessel. Further, we demonstrate that this technique results in stable incorporation of the delivered gene into the target endothelial cells for more than 30 days. These data demonstrate the utility of the retroviral gene delivery approach for optimizing the biologic phenotype of engineered vessels. This also provides the framework for testing an array of genes that may improve the function of engineered blood vessels after surgical implantation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63440/1/10763270360728198.pd

Biosynthesis, transport, and modification of lipid A

Lipopolysaccharide (LPS) is the major surface molecule of Gram-negative bacteria and consists of three distinct structural domains: O-antigen, core, and lipid A. The lipid A (endotoxin) domain of LPS is a unique, glucosamine-based phospholipid that serves as the hydrophobic anchor of LPS and is the bioactive component of the molecule that is associated with Gram-negative septic shock. The structural genes encoding the enzymes required for the biosynthesis of Escherchia coli lipid A have been identified and characterized. Lipid A is often viewed as a constitutively synthesized structural molecule. However, determination of the exact chemical structures of lipid A from diverse Gram-negative bacteria shows that the molecule can be further modified in response to environmental stimuli. These modifications have been implicated in virulence of pathogenic Gram-negative bacteria and represent one of the molecular mechanisms of microbial surface remodeling used by bacteria to help evade the innate immune response. The intent of this review is to discuss the enzymatic machinery involved in the biosynthesis of lipid A, transport of the molecule, and finally, those enzymes involved in the modification of its structure in response to environmental stimuli