Efficient myocyte gene delivery with complete cardiac surgical isolation in situ

Abstract

A novel cardiac surgical technique has been developed. This approach with cardiac isolation and retrograde delivery of vector through the coronary sinus results in efficient myocyte transduction in an adult large animal in vivo.

Designing Heart Performance by Gene Transfer

“…A guiding modality such as ultrasound or fluoroscopy is often used (377). The technique has also proven effective in a range of animal models including rodents, canines, and sheep (84,377,658). Some studies have used balloon catheters to occlude the vascular outflow of the heart in an attempt to further increase dwell time and pressure of the injectant (346).…”

“…A method with similar goals to the percutaneous catheters has been termed cardiac isolation or crossclamping (83,84,292,318). This is a widely varied method with many individual techniques.…”

“…Injection of the vector directly into the intravascular space results in poor transduction of the myocardium, and large amounts of Ad vector are acutely toxic, especially to the liver (720). However, when the cardiac circulation is isolated, either during transplantation studies or during heart-lung bypass, global transduction efficiencies of 30 -50% can be achieved (83,84,187,188,801,845). These techniques frequently make use of elevated hydrostatic pressure and permeabilizing adjuvants (187,188).…”

‘Recirculating cardiac delivery’ method of gene delivery should be called ‘non-recirculating’ method

“…In our approach, 3,4 we use cardiopulmonary bypass, and we truly isolate the heart and truly 'recirculate' as we (a) ligate the hemiazygous vein in sheep (dogs and humans do not have one); (b) collect 100% of blood that enters both coronary arteries when using an antegrade approach, as we recover not only from the coronary sinus but also from the left and right ventricular cavities all blood that returns through the Thebesian veins. Similarly, we can use a retrograde delivery approach and recover from the aortic root as well as from the ventricular cavities, including all Thebesian vein flow; 4 and finally, (c) unlike the approach of Byrne et al, 1 we are able to wash essentially all of the vector out of the circulation at the end of the recirculation period. 3,4 In the 'V-focus' method, virtually 100% of the vector has already been lost into the systemic circulation at the end of the 'recirculation' interval and thus can never be recovered.…”

“…Similarly, we can use a retrograde delivery approach and recover from the aortic root as well as from the ventricular cavities, including all Thebesian vein flow; 4 and finally, (c) unlike the approach of Byrne et al, 1 we are able to wash essentially all of the vector out of the circulation at the end of the recirculation period. 3,4 In the 'V-focus' method, virtually 100% of the vector has already been lost into the systemic circulation at the end of the 'recirculation' interval and thus can never be recovered. In summary, the proof that this is not a recirculation method lies in the fact that more than 99% of the vector is in the liver and not in the heart at the conclusion of the 'recirculation' interval.…”