Abstract: Objective To investigate the effect of PLGA-PEG scaffold incorporating angiopoietin 1(Ang1) loaded nanoparticle that was injected into the infarcted area of rat heart to protect the heart from infarction and explore potential mechanisms. Methods Rat models of myocardial infarction were replicated,and one week later SD rats were randomly divided into 3 groups:Ang1-PLGA-PEG injection group [injected with 100 μL nanoparticle suspension, about (1.61±0.05)μg Ang1](n=9),Ang1 injection group[injected with PBS solution of angiopoietin1(100 μL, 25 ng/μL)](n=8),the model control group(injected with 100 μL PBS solution)(n=8). Four weeks after injection,cardiac function was examined by echocardiography,scar tissue hyperplasia was measured by Masson staining, cardiomyocyte apoptosis and angiogenesis were detected by immunofluorescence. Results In comparison with other two groups,Ang1-PLGA-PEG injection group showed an increased blood vessel density in the infarcted area and maturity(P＜0.05),which prevented cardiomyocyte apoptosis (P＜0.05) The area of myocardial infarction was significantly decreased(P＜0.05), the remodeling of cardiomyopathy was reduced and these changes improved cardiac function (P＜0.05). Compared with the model control group, pure Ang1 injected into the surrounding area did not show curative effect (P＜0.05). Conclusions Injection of Ang1-PLGA-PEG nanoparticles into the infarcted area of left ventricle may promote vascular proliferation and facilitate the survival of cardiomyocytes,It provides an experimental basis for clinical application.

Key words: angiopoietin 1, PLGA-PEG nanoparticles, cardiac regeneration