Bradley Fletcher, M.D. / Ph.D. Asst. Professor Phone: 352-392- 8558 Office: R5-114 Academic Research Bldg. Email: bsfletch@ufl.edu Publications: Search PubMed

Research Interests

The major interest of my laboratory is the generation of novel non-viral approaches to gene therapy and their application. I will briefly discuss some of the projects we work on below.

Our laboratory focus is on the use of transposons, which are mobile elements of DNA. Specifically we are utilizing a recently described Tc1-like mariner transposon called Sleeping Beauty to facilitate genomic integration and long-term gene expression in animals (reviewed by Fernando and Fletcher, BioDrugs 20(4):219-229, 2006). Plasmid DNA encoding the transposon and transposase are delivered via polyethylenimine/DNA complexes with the primary goal of targeting endothelial cells in vivo . In a murine model, co-transfection of both reporter and transposase-expressing plasmids leads to long-term expression of the reporter secreted alkaline phosphatase (SEAP) (Liu et al., Molecular Therapy 10:97-105, 2004). We then used molecular approaches to enhance the efficiency of transposition by altering the amino acid sequence of the transposase protein (Baus et al., Molecular Therapy 12:1148-1156, 2005). We have since applied this approach to therapeutically relevant animal models to determine the efficacy of our gene delivery approach. Our models have included genes such as Factor VIII and endothelial nitric oxide synthase for the treatment of hemophilia (Liu et al., Molecular Therapy 13:1006-1015, 2006) and pulmonary hypertension (Liu et al., FASEB J . 20(14):2594-6, 2006), respectively. We have also obtained interesting results with a gene that influences T-cell function to prevent post-transplant graft rejection ( FASEB J . 20(13):2384-6, 2006 and Am J Respir Crit Care Med. , 173(5):566-72, 2006). Another recently initiated and funded project involves the use of this transposon system to target tumor vasculature. We anticipate that this technique will have enormous potential as a non-viral method of gene delivery in humans.

In addition to the Sleeping Beauty transposon we are also interested in comparing the efficiency of another recently described transposon called piggyBac. Experiments are underway to compare the relative efficiencies and targeting ability of Sleeping Beauty and piggyBac both in vitro and in vivo . Finally, we are interested in other aspects of non-viral gene delivery including episomal-based vectors and new formulations of various polymer carriers to improve in vivo delivery of DNA to specific organs or cellular targets.

Expertise:
Areas of expertise: molecular biology; Northern and Southern blots; cDNA library construction; cloning and vector design/construction; viral gene transfer with murine retroviral systems; adenovirus; transposons; cell transfections; and FACS.