Experimental Study On Effect Of AAV9-SERCA2a Gene Transfected On Atrial Fibrillation

Objective：To explore the effects of AAV9-SERCA2a gene transfected on atrial electricalremodeling and structure remodeling in atrial fibrillation(AF) rabbits by24h rapid atrialpacing.Method：Forty-eight New Zealand rabbits were randomized into four groups (n=12),includingcontrol group,AFgroup, rAAV9+EGFP+AFgroupand rAAV9+SERCA2a+EGFP+AFgroup.rAAV9-EGFP and rAAV9-SERCA2a-EGFP(1.0×1012v.g/μL for each animal)were injected intopericardium of the animals of rAAV9+EGFP+AF and rAAV9+SERCA2a+(enhanced greenfluorescent protein)EGFP+AF groups before rapid atrial pacing thirty day. Thirty day after genetransfection,AF was induced by rapid atrial pacing(600beats／min)for24hours in each animal of AFgroup,rAAV9+EGFP+AF group and rAAV9+SERCA2a+EGFP+AF group.Each animal of controlgroup was not paced,Animals were scarified to observe expression of the green fluorescent protein inthe myocardial frozen section of rabbits in rAAV9+EGFP+AF group under the inverted fluorescencemicroscope, The changes of the AF induction rate and atrial effective refractory period(AERP) wereobserved0,4,8,12,16and24hours after pacing.Left and right atrial diameter and left ven-tricularejection fraction(EF) were examined by cardiac ultrasonography. The changes of atrial structure wereexaminated by light and electron microscopy. The changes of the expressions of SERCA2a protein andLVDCCalc protein in the right atrial tissue in each group was detected by immunohistochemistry.Result：Under the optical microscope and electron microscope, the changes of atrial structure wasobserved in each animal. Under the fluorescence microscope, widespread green fluorescence wasobserved in the myocardial frozen section of rabbits in EGFP+AF group. The AF induction ratedecrease in rAAV9+SERCA2a+EGFP+AF group.There was no difference in the AERP between AFgroup and EGFP+AFgroup(P>0.05).AERP was unmarkedly shortened in SERCA2a+EGFP+AFgroupcompared with AF group and EGFP+AFgroup after pacing for12hours(P<0.05). Compared with AFgroup and rAAV9+EGFP+AF group, The left and right atrial volume of rabbits in rAAV9+SERCA2a +EGFP+AF group were encharged and left ven-tricular ejection fraction(EF) was decreased,but therewas no significance;Compared with AF group and rAAV9+EGFP+AF group(P<0.05),expressions ofSERCA2a protein and LVDCCalc protein in the right atrium of rabbits in rAAV9+SERCA2a+EGFP+AF group was significantly upregulated and the change of the right atrial tissue myopathy wasreduced.Conclusion：These results support the hypothesis that overexpression of SERCA2ais able to reverse the atrial electrophysiologic remodeling and structure remodeling in AFrabbits induced by rapid atrial pacing.The study demonstrates that gene transfer ofSERCA2a into cardiac with recombinant adeno-associated virus9vector is a promisingtherapy method.