Image-guided cardiac cell delivery using high-resolution small-animal ultrasound.

Open-chest cardiac injection is the preferred delivery method for cardiac gene and stem cell therapy in small animals, but it is invasive and the operator is unable to see the actual delivery site. High-resolution ultrasound has recently been developed for small-animal imaging. We tested the hypothesis that image-guided cardiac cell delivery using high-resolution ultrasound guidance is feasible and reproducible. Sprague-Dawley rats (n = 11) were imaged using high-resolution ultrasound, and stably transfected cardiomyoblasts (plasmid-CMV-firefly luciferase) were injected into the anterior cardiac wall under ultrasound guidance (parasternal long-axis view), using a 28-gauge needle. After injection, bioluminescence imaging was performed using a cooled charged-coupled camera. Injection was successful in all animals and was associated with no mortality. The signal detected was positively correlated with the amount of cells transplanted (R(2) = 0.94, P = 0.03) and highly correlated with ex vivo assays (R(2) = 0.82). In addition, the optical signal could be followed longitudinally using bioluminescence imaging. Ultrasound image-guided cardiac cell delivery is an effective, safe, and reproducible way to perform cell delivery to a specific myocardial region and can be combined with assessment of cardiac function. We are confident that the use of these technologies will play a significant role in the future of gene and cell therapy.