title: Targeted endothelial gene delivery by ultrasonic destruction of magnetic microbubbles carrying lentiviral vectors.
abstract: OBJECTIVE
  Site specific vascular gene delivery is a promising tool for treatment of cardiovascular diseases. By combining ultrasound mediated microbubble destruction with site specific magnetic targeting of lentiviruses, we aimed to develop a technique suitable for systemic application.
  
  
  METHODS
  The magnetic nanoparticle coupling to lipid microbubbles was confirmed by absorbance measurements. Association of fluorescent lentivirus to magnetic microbubbles (MMB) was determined by microscopy and flow cytometry. Functionality and efficiency of GFP-encoding lentiviral MMB transduction was evaluated by endothelial (HMEC) GFP expression and cytotoxicity was measured by MTT reduction.
  
  
  RESULTS
  Microbubbles with a mean diameter of 4.3 ± 0.04 μm were stable for 2 days, readily magnetizable and magnetically steerable in vitro and efficiently associated with lentivirus. Exposure of eGFP-encoding lentiviral MMB to human endothelial cells followed by application of an external static magnetic field (30 min) and ultrasonic destruction of the microbubbles did not markedly affect cellular viability. Finally, this combination led to a 30-fold increase in transduction efficiency compared to application of naked virus alone.
  
  
  CONCLUSIONS
  By associating microbubbles with magnetic iron nanoparticles, these function as carriers for lentiviruses achieving tissue specific deposition at the site of interest.
authors.affiliation: Walter-Brendel-Centre of Experimental Medicine, Schillerstrasse 44, 80336 Munich, Germany.
authors.forename: Hanna
authors.initials: H
authors.lastname: Mannell
authors.forename: Joachim
authors.initials: J
authors.lastname: Pircher
authors.forename: Thomas
authors.initials: T
authors.lastname: Räthel
authors.forename: Katharina
authors.initials: K
authors.lastname: Schilberg
authors.forename: Katrin
authors.initials: K
authors.lastname: Zimmermann
authors.forename: Alexander
authors.initials: A
authors.lastname: Pfeifer
authors.forename: Olga
authors.initials: O
authors.lastname: Mykhaylyk
authors.forename: Bernhard
authors.initials: B
authors.lastname: Gleich
authors.forename: Ulrich
authors.initials: U
authors.lastname: Pohl
authors.forename: Florian
authors.initials: F
authors.lastname: Krötz
mesh_terms: D002470:Cell Survival; D016503:Drug Delivery Systems; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D005434:Flow Cytometry; D018014:Gene Transfer Techniques; D005822:Genetic Vectors / Q000235:genetics*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D016086:Lentivirus / Q000235:genetics*; D008280:Magnetics; D045423:Microbubbles; D010316:Particle Size; D014465:Ultrasonics
chemical_list: D049452:Green Fluorescent Proteins