Angiopoietin-1 for myocardial angiogenesis: a comparison between delivery strategies

We compare the effectiveness of direct adenoviral angiopoietin-1 (Ad-Ang-1) injection with transplantation of skeletal myoblasts (SkMs) over-expressing angiopoietin-1 (Ang-1) for angiogenic response and improvement of heart function in an experimental porcine model of myocardial infarction (MI).

Ad-Ang-1 was used for intramyocardial injection or transduction of SkMs. Three weeks after coronary artery ligation in 32 female pigs, animals were grouped to receive multiple intramyocardial injections of DMEM without cells (group-1; n=7), or containing 3 x 10(8)Lac-z labelled SkMs transduced with Ad-Null vector carrying no gene (group-2; n=7), or 1 x 10(10) PFU Ad-Ang-1 (group-3; n=9), or 3 x 10(8)Lac-z labelled SkMs transduced with Ad-Ang-1 (group-4; n=9). The animals were immunosuppressed for 6-weeks. After euthanasia, their heart tissue was processed for histological studies.

Extensive survival of Lac-z positive SkMs was observed in and around the infarct 6 and 12-weeks after transplantation. Fluorescent immunostaining for vWF-VIII at 6-weeks revealed increased blood vessel density (x100) in group-4 (p<0.05) as compared with other groups. Regional blood flow (ml/g/min) in the peri-infarct area was improved in group-4 (2.7; p<0.05) as compared with group-1 (1.2+/-0.1), group-2 (1.1+/-0.4) and group-3 (1.7+/-0.1) at 6-weeks. Similarly, ejection fraction was significantly higher in group-4 (49.2+/-5.9%, p=0.03) as compared with group-1 (36.8+/-3%) at 6 weeks.

SkMs mediated Ang-1 delivery is associated with improved angiogenic response, regional myocardial perfusion and heart function as compared with direct Ad-Ang-1 administration.