title: Radiofrequency-enhanced vascular gene transduction and expression for intravascular MR imaging-guided therapy: feasibility study in pigs.
abstract: OBJECTIVE
  To evaluate the feasibility of radiofrequency (RF)-enhanced vascular gene transduction and expression by using a magnetic resonance (MR) imaging-heating guidewire as an intravascular heating vehicle during MR imaging-guided therapy.
  
  
  METHODS
  The institutional committee for animal care and use approved the experimental protocol. The study included in vitro evaluation of the use of RF energy to enhance gene transduction and expression in vascular cells, as well as in vivo validation of the feasibility of intravascular MR imaging-guided RF-enhanced vascular gene transduction and expression in pig arteries. For in vitro experiments, approximately 10(4) vascular smooth muscle cells were seeded in each of four chambers of a cell culture plate. Next, 1 mL of a green fluorescent protein gene (gfp)-bearing lentivirus was added to each chamber. Chamber 4 was heated at approximately 41 degrees C for 15 minutes by using an MR imaging-heating guidewire connected to a custom RF generator. At day 6 after transduction, the four chambers were examined and compared at confocal microscopy to determine the efficiency of gfp transduction and expression. For the in vivo experiments, a lentivirus vector bearing a therapeutic gene, vascular endothelial growth factor 165 (VEGF-165), was transferred by using a gene delivery balloon catheter in 18 femoral-iliac arteries (nine artery pairs) in domestic pigs and Yucatan pigs with atherosclerosis. During gene infusion, one femoral-iliac artery in each pig was heated to approximately 41 degrees C with RF energy transferred via the intravascular MR imaging-heating guidewire, while the contralateral artery was not heated (control condition). At day 6, the 18 arteries were harvested for quantitative Western blot analysis to compare VEGF-165 transduction and expression efficiency between RF-heated and nonheated arterial groups.
  
  
  RESULTS
  Confocal microscopy showed gfp expression in chamber 4 that was 293% the level of expression in chamber 1 (49.6% +/- 25.8 vs 16.8% +/- 8.0). Results of Western blot analysis showed VEGF-165 expression for normal arteries in the RF-heated group that was 300% the level of expression in the nonheated group (70.4 arbitrary units [au] +/- 107.1 vs 23.5 au +/- 29.8), and, for atherosclerotic arteries in the RF-heated group, 986% the level in the nonheated group (129.2 au +/- 100.3 vs 13.1 au +/- 4.9).
  
  
  CONCLUSIONS
  Simultaneous monitoring and enhancement of vascular gene delivery and expression is feasible with the MR imaging-heating guidewire.
authors.affiliation: Department of Radiology, Johns Hopkins University School of Medicine, Traylor Bldg, Room 330, 720 Rutland Ave, Baltimore, MD 21205, USA.
authors.forename: Xiangying
authors.initials: X
authors.lastname: Du
authors.forename: Bensheng
authors.initials: B
authors.lastname: Qiu
authors.forename: Xiangcan
authors.initials: X
authors.lastname: Zhan
authors.forename: Antonina
authors.initials: A
authors.lastname: Kolmakova
authors.forename: Fabao
authors.initials: F
authors.lastname: Gao
authors.forename: Lawrence V
authors.initials: LV
authors.lastname: Hofmann
authors.forename: Linzhao
authors.initials: L
authors.lastname: Cheng
authors.forename: Subroto
authors.initials: S
authors.lastname: Chatterjee
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Yang
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002404:Catheterization / Q000379:methods*; D005240:Feasibility Studies; D015316:Genetic Therapy; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins; D006979:Hyperthermia, Induced / Q000379:methods*; D016086:Lentivirus / Q000235:genetics; D008279:Magnetic Resonance Imaging; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D000078702:Radiofrequency Therapy; D013552:Swine; D014652:Vascular Diseases / Q000628:therapy*
chemical_list: D049452:Green Fluorescent Proteins