Many genetic and acquired diseases of the liver can be theoretically treated with gene therapy. The efficiency of non-viral vectors typically falls behind that of viral vectors, except the hydrodynamic injection method. However, the invasiveness of the hydrodynamic procedure is probably not acceptable beyond serving as a research tool. Dr. Leaf Huang et al. have recently developed a nanoparticle formulation consisting of an amorphous calcium phosphate core wrapped with a single lipid bilayer membrane. The nanoparticles are named LCP (lipid/calcium/phosphate). Galactose targeted LCP containing both a plasmid DNA and a decapeptide CR8C showed a high level of gene transfection in the liver hepatocytes of mice after tail vein injection in a non-hydrodynamic manner. The presence of CR8C was essential for nuclear localization of the injected plasmid DNA. Preliminary data suggest that CR8C, although essential for the nuclear import of the condensed plasmid DNA, dose not efficiently dissociate from the DNA in the nucleus.
Aim 1 of the proposed study will test a series of histone peptides, with and without the addition of oligoarginines, which can be covalently modified by nuclear enzymes to reduce the cationic charge content of the peptides. The hypothesis is that the histone peptide(s) will condense the plasmid DNA and bring it into the nucleus, but dissociate from the DNA after covalent modification in situ. Such controlled release of the plasmid DNA should allow the DNA for enhanced transcription. Since the plasmid DNA accumulated in the nuclei of the hepatocytes, it is important to study the mechanism underlying the efficient import.
Aim 2 is designed to test the hypothesis that transiently elevated Ca concentration as a result of LCP releasing its cargo from the endosome will stimulate the nuclear import of the plasmid DNA/CR8C complex. Various cell biology experiments, including the ones using time- lapsed live-cell confocal microscopy, have been proposed. Over 2 billion people have been infected with the hepatitis B virus (HBV) and 350 million live with chronic HBV infection worldwide, about 25% of whom die from liver fibrosis/cirrhosis or liver cancer caused by the infection (WHO: Hepatitis B-Key facts). Although a preventive HBV vaccine is available, there is no cure for the 350 million patients who are already chronically infected. Dr. Lishan Su at UNC has developed a humanized mouse model (AFC8-hu) which contains not only the human hepatocytes in the liver but also the human immune system. The mice can be infected by HBV and develop hepatitis symptoms, including fatty liver, fibrosis and inflammation. Type-1 interferons are effective anti-virals, especially fo the viral hepatitis such as HBV. In preliminary experiments, IFN-?2b could be expressed at the clinically relevant concentration in the liver of mouse injected with a plasmid containing the cDNA for IFN-?2b using LCP as a vector.
In Aim 3, we will test the IFN gene therapy in the AFC8-hu mice chronically infected with HBV. S/MAR sequence will be incorporated into the IFN-?2b plasmid to prolong the gene expression. The goal is to develop a once-a-month IFN gene therapy for the HBV hepatitis patients.
A nanoparticle formulation has been developed for efficient liver expression of a transgene by IV administration. The project aims at further improvement of the gene delivery efficiency to the liver. It will also develop an interferon gene therapy using a HBV infectable chimeric mouse model which harbors both the human hepatocytes and the human immune system.
|Liu, Yang; Hu, Yunxia; Huang, Leaf (2014) Influence of polyethylene glycol density and surface lipid on pharmacokinetics and biodistribution of lipid-calcium-phosphate nanoparticles. Biomaterials 35:3027-34|