Targeted modification of atrial electrophysiology by homogeneous transmural atrial gene transfer.
BACKGROUND
Safe and effective myocardial gene transfer remains elusive. Heterogeneous ventricular gene delivery has been achieved in small mammals but generally with methods not readily transferable to the clinic. Atrium-specific gene transfer has not yet been reported. We hypothesized that homogeneous atrial gene transfer could be achieved by direct application of adenoviral vectors to the epicardial surface, use of poloxamer gel to increase virus contact time, and mild trypsinization to increase virus penetration.


RESULTS
We "painted" recombinant adenovirus encoding the reporter gene Escherichia coli beta-galactosidase directly onto porcine atria. Investigational variables included poloxamer use, trypsin concentration, and safety. Using the painting method, we modified the atrial phenotype with an adenovirus expressing HERG-G628S, a long-QT-syndrome mutant. Our results showed that application of virus with poloxamer alone resulted in diffuse epicardial gene transfer with negligible penetration into the myocardium. Dilute trypsin concentrations allowed complete transmural gene transfer. After trypsin exposure, echocardiographic left atrial diameter did not change. Left atrial function decreased on postoperative day 3 but returned to baseline by day 7. Tissue tensile strength was affected only in the 1% trypsin group. HERG-G628S gene transfer prolonged atrial action potential duration and refractory period without affecting ventricular electrophysiology.


CONCLUSIONS
We show complete transmural atrial gene transfer by this novel painting method. Adaptation of the method could allow application to other tissue targets. Use with functional proteins in the atria could cure or even prevent diseases such as atrial fibrillation or sinus node dysfunction.
Kikuchi
Kan
K
Johns Hopkins University School of Medicine, Baltimore, Md 21205, USA.
McDonald
Amy D
AD
Sasano
Tetsuo
T
Donahue
J Kevin
JK
D000200:Action Potentials; D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D016279:Atrial Function, Left; D004452:Echocardiography; D004562:Electrocardiography; D018014:Gene Transfer Techniques / Q000009:adverse effects; D017930:Genes, Reporter; D005822:Genetic Vectors; D006325:Heart Atria / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D009154:Mutation; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D010496:Pericardium / Q000378:metabolism; D020442:Poloxamer; D024642:Potassium Channels, Voltage-Gated / Q000235:genetics; D013552:Swine; D013718:Tensile Strength; D014357:Trypsin; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics
D024642:Potassium Channels, Voltage-Gated; D020442:Poloxamer; D001616:beta-Galactosidase; D014357:Trypsin