Nanoparticle mediated delivery of chemically modified PNA for beta thalassemia gene therapy provoked by DNA repair

Postdoc Assoc Ther Radiology
15 York St, New Haven, CT 06510-3221

Beta thalassemia is one of the most common autosomal recessive disorders caused by reduced or absent synthesis of beta globin chains of hemoglobin tetramer. More than 200 disease-causing mutations have been identified so far, and the most frequent ones are point mutations. Though conventional gene therapy efforts based on the introduction of recombinant cDNA constructs have shown promising results, they still have not provided a cure. Our lab has comprehensively demonstrated that altered helices formed by triplex-forming oligonucleotides (TFOs) constitute a form of DNA “damage” that can provoke DNA repair and thereby catalyze site-specific recombination in human cells. In further advancements, we have also demonstrated that triplex-forming peptide nucleic acids (TFPs), which are neutral and resistant to enzymatic degradation, can form PNA/DNA/PNA triplexes with displacement of one strand of the duplex DNA, producing structures that are highly provocative of DNA repair. In collaboration with Saltzman’s lab, we have also shown that FDA-approved poly lactic-co-glycolic acid (PLGA)-based nanoparticle can be used as a carrier for TFP/donor DNAs for gene correction. However for clinical application, triplex-forming technology still possesses some limitations. Firstly, use of TFPs requires the presence of relatively long homopurine sequences in the vicinity of the target site. Secondly, the gene correction frequency is low. Our recent findings suggest that PNA reagent optimization combined with nanoparticles based delivery approach can enhance the gene correction frequency without the need for long homopurine stretches in the targeted region.