Targeted Myocardial Microinjections of a Biocomposite Material Reduces Infarct Expansion in Pigs

Background Left ventricular (LV) remodeling after myocardial infarction (MI) commonly causes infarct expansion (IE). This study sought to interrupt IE through microinjections of a biocompatible composite material into the post-MI myocardium. Methods MI was created in 21 pigs (coronary ligation). Radiopaque markers (2-mm diameter) were placed for IE (fluoroscopy). Pigs were randomized for microinjections (25 injections; 2- × 2-cm array; 200 μL/injection) at 7 days post-MI of a fibrin-alginate composite (Fib-Alg; fibrinogen, fibronectin, factor XIII, gelatin-grafted alginate, thrombin; n=11) or saline (n = 10). Results At 7 days after injection (14 days post-MI), LV posterior wall thickness was higher in the Fib-Alg group than in the saline group (1.07 ± 0.11 vs 0.69 ± 0.07 cm, respectively, p = 0.002). At 28 days post-MI, the area within the markers (IE) increased from baseline (1 cm 2 ) in the saline (1.71 ± 0.13 cm 2 , p = 0.010) and Fib-Alg groups (1.44 ± 0.23 cm 2 , p p =0.043 and p =0.019). Total collagen content within the MI region was similar in the saline and Fib-Alg groups (12.8 ± 1.7 and 11.6 ± 1.5 μg/mg, respectively, p = NS). However, extractable collagen, indicative of solubility, was lower in the Fib-Alg group than the saline group (59.1 ± 3.5 vs 71.0 ± 6.1 μg/mL, p = 0.020). Conclusions Targeted myocardial microinjection of the biocomposite attenuated the post-MI decrease in LV wall thickness and infarct expansion. Thus, intraoperative microinjections of biocompatible material may provide a novel approach for interrupting post-MI LV remodeling.