Berberin Sustained-release Nanoparticles were Enriched in Infarcted Rat Myocardium and Resolved Inflammation

Introduction: Inflammatory regulation induced by macrophage polarization is essential for cardiac repair after myocardial infarction (MI). Berberin (BBR) is an isoquinoline tetrasystemic alkaloid extracted from plants with anti-inflammatory and antioxidant effects. The most likely mechanism of Berberin (BBR) in MI treatment determined via network pharmacology show that BBR acts mainly through inflammatory responses. This study aims to construct a BBR sustained-release nanodrug that could be enriched in infarcted myocardium for MI treatment and to verify the most likely mechanism.

Methods: Gene Ontology enrichment analysis was performed to reveal the biological characteristics of 200 intersecting target genes. PLGA nanoparticles loaded with berberin were prepared by emulsification method. The nanoparticles were coated with PLT membranes extracted from SD rats and labeled with DSPE-PEG₂₀₀₀-Cy7 by hydrophobic insertion. The morphology of the BBR@PLGA@PLT nanoparticles was observed by transmission electron microscopy (TEM), and the particle size and stability of the nanoparticles were measured by dynamic light scattering instrument (DLS). Acute myocardial infarction was established in SD rats by ligating the left anterior descending branch of coronary artery. Fifteen minutes after the successful establishment of the model, Cy7-labeled bionic nanoparticles containing 0.8 mg berberine were injected from the rat tail vein. One day later, the heart, liver, spleen, lung, and kidney of the rat were removed to observe the fluorescence distribution in these tissues. The experimental group was injected with 1mg bionic berberine nanoparticle in the tail vein, while the blank control group was injected with normal saline. On the third day after MI. Immunofluorescence staining was used to assess the M2-type proportion of macrophages at day 3 of myocardial infarction in rats. After 28 days of myocardial infarction, the function of the left ventricle was detected by ultrasound, and the proportion of angiogenesis and myocardiocyte apoptosis was evaluated by immunofluorescence staining.

Results: After excluding too general items, Gene Ontology enrichment analysis showed that inflammation resolution might be the most important mechanism in the treatment of myocardial infarction by BBR. The peak hydration particle size of BBR@PLGA nanoparticles and BBR@PLGA@PLT were 210.66nm and 231.45nm, and Zeta potential was 10.60mV±1.97mV and -10.84 mV± 1.62 mV, respectively. After intravenous injection of Cy7-labeled BBR@PLGA@PLT1 in MI rats, fluorescence imaging showed that nanoparticles were enriched in infarcted myocardium. The fluorescence intensity of the myocardium in the BBR@PLGA group was not different from that in the background. Compared with the Saline group and BBR@PLGA group, BBR@PLGA@PLT significantly promoted M1-type macrophages to M2-type macrophages polarization on the third day after MI. On the 28th day after MI, the BBR@PLGA@PLT group exhibits a protective effect on cardiac function, reduced cardiac collagen deposition, improved scar tissue stiffness, and an excellent angiogenesis effect. In addition, BBR@PLGA@PLT has no significant impact on major organs either histologically or enzymologically. The therapeutic effect of BBR@PLGA@PLT on MI is presented in detail from the perspective of the resolution of inflammation, and a new solution for MI treatment is proposed.

Conclusions: We successfully developed a BBR sustained-release nanomedicine that can be enriched in infarcted myocardium and used in MI therapy. And we demonstrated that BBR@PLGA@PLT could protect cardiac function, reduce adverse heart remodeling, protect cardiomyocytes, and promote angiogenesis of infarcted myocardium. This study indicates a new direction for MI treatment.