Intramyocardial microdepot injection increases the efficacy of skeletal myoblast transplantation.

Objective: Recent progress in the field of cellular cardiomyoplasty has opened new prospects for the treatment of ischemic heart disease and currently moves from bench to bedside. The aim of the present study was to develop a novel cell delivery technique, reducing target tissue damage and improving cell dispersion and engraftment.

Methods: In 30 male Fischer F344 rats an infarction of the left ventricle was generated by ligation of the left anterior descendent artery. Seven days after infarction, either 15 microdepots of 10 microl myoblast cell suspension (microdepot group) or culture medium (control group) were injected into the infarcted region using an automatic pressure injection device, or three depots of 50 microl myoblast cell suspension (macrodepot group) were injected using the standard surgical technique. Echocardiography was performed in all rats before and 6 weeks after cell injection. In all groups the perioperative mortality was below 20%. Six weeks after cell transplantation, a significant improvement of ejection fraction was seen in both myoblast treated groups compared to controls (macrodepot, microdepot, control; 53.7+/-11.9, 70.7+/-2.0, 39.1+/-6.4; P=0.026, P<0.001). The microdepot group showed a more decent improvement than the macrodepot group (70.7+/-2.0 vs. 53.7+/-11.9, P=0.013). In both treated groups, grafted myoblasts differentiated into multinucleated myotubes within host myocardium, however, the engraftment pattern was different and angiogenesis was enhanced in the microdepot group.

Conclusions: Intramyocardial multisite pressure injection allows the safe and reliable transplantation of several myoblast microdepots into an infarcted myocardium and improves the efficacy of myoblast transplantation compared to the standard technique.