Biomimetic Nano-Degrader Based CD47-SIRPα Immune Checkpoint Inhibition Promotes Macrophage Efferocytosis for Cardiac Repair.

CD47-SIRPα axis is an immunotherapeutic target in tumor therapy. However, current monoclonal antibody targeting CD47-SIRPα axis is associated with on-target off-tumor and antigen sink effects, which significantly limit its potential clinical application. Herein, a biomimetic nano-degrader is developed to inhibit CD47-SIRPα axis in a site-specific manner through SIRPα degradation, and its efficacy in acute myocardial infarction (AMI) is evaluated. The nano-degrader is constructed by hybridizing liposome with red blood cell (RBC) membrane (RLP), which mimics the CD47 density of senescent RBCs and possesses a natural high-affinity binding capability to SIRPα on macrophages without signaling capacity. RLP would bind with SIRPα and induce its lysosomal degradation through receptor-mediated endocytosis. To enhance its tissue specificity, Ly6G antibody conjugation (aRLP) is applied, enabling its attachment to neutrophils and accumulation within inflammatory sites. In the myocardial infarction model, aRLP accumulated in the infarcted myocardium blocks CD47-SIRPα axis and subsequently promoted the efferocytosis of apoptotic cardiomyocytes by macrophage, improved heart repair. This nano-degrader efficiently degraded SIRPα in lysosomes, providing a new strategy for immunotherapy with great clinical transformation potential.

Genetically Engineered Macrophages Co-Loaded with CD47 Inhibitors Synergistically Reconstruct Efferocytosis and Improve Cardiac Remodeling Post Myocardial Ischemia Reperfusion Injury.

Efferocytosis, mediated by the macrophage receptor MerTK (myeloid-epithelial-reproductive tyrosine kinase), is a significant contributor to cardiac repair after myocardial ischemia-reperfusion (MI/R) injury. However, the death of resident cardiac macrophages (main effector cells), inactivation of MerTK （main effector receptor), and overexpression of "do not eat me" signals (brake signals, such as CD47), collectively lead to the impediment of efferocytosis in the post-MI/R heart. To date, therapeutic strategies targeting individual above obstacles are relatively lacking, let alone their effectiveness being limited due to constraints from the other concurrent two. Herein, inspired by the application research of chimeric antigen receptor macrophages (CAR-Ms) in solid tumors, a genetically modified macrophage-based synergistic drug delivery strategy that effectively challenging the three major barriers in an integrated manner is developed. This strategy involves the overexpression of exogenous macrophages with CCR2 (C-C chemokine receptor type 2) and cleavage-resistant MerTK, as well as surface clicking with liposomal PEP-20 (a CD47 antagonist). In MI/R mice model, this synergistic strategy can effectively restore cardiac efferocytosis after intravenous injection, thereby alleviating the inflammatory response, ultimately preserving cardiac function. This therapy focuses on inhibiting the initiation and promoting active resolution of inflammation, providing new insights for immune-regulatory therapy.

Myocardial infarction drives trained immunity of monocytes, accelerating atherosclerosis.

BACKGROUND AND AIMS: Survivors of acute coronary syndromes face an elevated risk of recurrent atherosclerosis-related vascular events despite advanced medical treatments. The underlying causes remain unclear. This study aims to investigate whether myocardial infarction (MI)-induced trained immunity in monocytes could sustain proatherogenic traits and expedite atherosclerosis. METHODS: Apolipoprotein-E deficient (ApoE-/-) mice and adoptive bone marrow transfer chimeric mice underwent MI or myocardial ischaemia-reperfusion (IR). A subsequent 12-week high-fat diet (HFD) regimen was implemented to elucidate the mechanism behind monocyte trained immunity. In addition, classical monocytes were analysed by flow cytometry in the blood of enrolled patients. RESULTS: In MI and IR mice, blood monocytes and bone marrow-derived macrophages exhibited elevated spleen tyrosine kinase (SYK), lysine methyltransferase 5A (KMT5A), and CCHC-type zinc finger nucleic acid-binding protein (CNBP) expression upon exposure to a HFD or oxidized LDL (oxLDL) stimulation. MI-induced trained immunity was transmissible by transplantation of bone marrow to accelerate atherosclerosis in naive recipients. KMT5A specifically recruited monomethylation of Lys20 of histone H4 (H4K20me) to the gene body of SYK and synergistically transactivated SYK with CNBP. In vivo small interfering RNA (siRNA) inhibition of KMT5A or CNBP potentially slowed post-MI atherosclerosis. Sympathetic denervation with 6-hydroxydopamine reduced atherosclerosis and inflammation after MI. Classical monocytes from ST-elevation MI (STEMI) patients with advanced coronary lesions expressed higher SYK and KMT5A gene levels. CONCLUSIONS: The findings underscore the crucial role of monocyte trained immunity in accelerated atherosclerosis after MI, implying that SYK in blood classical monocytes may serve as a predictive factor for the progression of atherosclerosis in STEMI patients.

Hippo pathway-manipulating neutrophil-mimic hybrid nanoparticles for cardiac ischemic injury via modulation of local immunity and cardiac regeneration.

The promise of regeneration therapy for restoration of damaged myocardium after cardiac ischemic injury relies on targeted delivery of proliferative molecules into cardiomyocytes whose healing benefits are still limited owing to severe immune microenvironment due to local high concentration of proinflammatory cytokines. Optimal therapeutic strategies are therefore in urgent need to both modulate local immunity and deliver proliferative molecules. Here, we addressed this unmet need by developing neutrophil-mimic nanoparticles NM@miR, fabricated by coating hybrid neutrophil membranes with artificial lipids onto mesoporous silica nanoparticles (MSNs) loaded with microRNA-10b. The hybrid membrane could endow nanoparticles with strong capacity to migrate into inflammatory sites and neutralize proinflammatory cytokines and increase the delivery efficiency of microRNA-10b into adult mammalian cardiomyocytes (CMs) by fusing with cell membranes and leading to the release of MSNs-miR into cytosol. Upon NM@miR administration, this nanoparticle could home to the injured myocardium, restore the local immunity, and efficiently deliver microRNA-10b to cardiomyocytes, which could reduce the activation of Hippo-YAP pathway mediated by excessive cytokines and exert the best proliferative effect of miR-10b. This combination therapy could finally improve cardiac function and mitigate ventricular remodeling. Consequently, this work offers a combination strategy of immunity modulation and proliferative molecule delivery to boost cardiac regeneration after injury.

Targeted delivery and ROS-responsive release of Resolvin D1 by platelet chimeric liposome ameliorates myocardial ischemia-reperfusion injury.

Resolvin D1 (RvD1) has been shown to provide effective protection against ischemia-reperfusion injury in multiple vital organs such as the heart, brain, kidney. However, the clinical translational potential of systemic administration of RvD1 in the treatment of ischemia-reperfusion injury is greatly limited due to biological instability and lack of targeting ability. Combining the natural inflammatory response and reactive oxygen species (ROS) overproduction after reperfusion injury, we developed a platelet-bionic, ROS-responsive RvD1 delivery platform. The resulting formulation enables targeted delivery of RvD1 to the injury site by hijacking circulating chemotactic monocytes, while achieving locally controlled release. In a mouse model of myocardial ischemia repefusuin (MI/R) injury, intravenous injection of our formula resulted in the enrichment of RvD1 in the injured area, which in turn promotes clearance of dead cells, production of specialized proresolving mediators (SPMs), and angiogenesis during injury repair, effectively improving cardiac function. This delivery system integrates drug bio-protection, targeted delivery and controlled release, which endow it with great clinical translational value.

Targeted neutrophil-mimetic liposomes promote cardiac repair by adsorbing proinflammatory cytokines and regulating the immune microenvironment.

Acute myocardial infarction (MI) induces a sterile inflammatory response that may result in poor cardiac remodeling and dysfunction. Despite the progress in anti-cytokine biologics, anti-inflammation therapy of MI remains unsatisfactory, due largely to the lack of targeting and the complexity of cytokine interactions. Based on the nature of inflammatory chemotaxis and the cytokine-binding properties of neutrophils, we fabricated biomimetic nanoparticles for targeted and broad-spectrum anti-inflammation therapy of MI. By fusing neutrophil membranes with conventional liposomes, we fabricated biomimetic liposomes (Neu-LPs) that inherited the surface antigens of the source cells, making them ideal decoys of neutrophil-targeted biological molecules. Based on their abundant chemokine and cytokine membrane receptors, Neu-LPs targeted infarcted hearts, neutralized proinflammatory cytokines, and thus suppressed intense inflammation and regulated the immune microenvironment. Consequently, Neu-LPs showed significant therapeutic efficacy by providing cardiac protection and promoting angiogenesis in a mouse model of myocardial ischemia-reperfusion. Therefore, Neu-LPs have high clinical translation potential and could be developed as an anti-inflammatory agent to remove broad-spectrum inflammatory cytokines during MI and other neutrophil-involved diseases.

Targeted immunomodulation therapy for cardiac repair by platelet membrane engineering extracellular vesicles via hitching peripheral monocytes.

Immune regulation therapies have been considered promising in the treatment of myocardial ischemia reperfusion (MI/R) injury. Mesenchymal stem cells derived extracellular vesicles (MSC-EVs) are of great potential for immune modulation by reprogramming macrophages but their therapeutic efficacy is hindered by insufficient targeting ability in vivo. Herein, we introduced the platelet membrane modified EVs (P-EVs) based on membrane fusion method to mimic the binding ability of platelets to monocytes. In the mouse model of MI/R injury, the intravenously injected P-EVs were mainly carried by circulating monocytes into the ischemic myocardium. In the inflammatory microenvironment, those monocytes subsequently differentiated into macrophages with enhanced phagocytosis, which probably promoted in-situ endocytosis of the superficial P-EVs by monocytes differentiated macrophages in large quantities. Then, the P-EVs successfully escaped from the macrophage lysosome and released the functional microRNAs (miRNAs) into the cytosol which facilitated the inflammatory macrophages (M1 phenotype) reprogramming to reparative macrophages (M2 phenotype). Finally, the immune microenvironment was regulated to realize cardiac repair. Thus, we supposed that the most likely delivery method was that monocytes mediated P-EVs migration into ischemic myocardium where P-EVs were mainly in-situ endocytosed by monocytes derived macrophages, which holds potential for immunoregulation on MI/R and other immune-related diseases in the future.

Direct in vivo reprogramming with non-viral sequential targeting nanoparticles promotes cardiac regeneration.

microRNA-mediated direct cardiac reprogramming, directly converts fibroblasts into induced cardiomyocyte-like cells (iCMs), which holds great promise in cardiac regeneration therapy. However, effective approaches to deliver therapeutic microRNA into cardiac fibroblasts (CFs) to induce in vivo cardiac reprogramming remain to be explored. Herein, a non-viral biomimetic system to directly reprogram CFs for cardiac regeneration after myocardial injury was developed by coating FH peptide-modified neutrophil-mimicking membranes on mesoporous silicon nanoparticles (MSNs) loaded with microRNA1, 133, 208, and 499 (miR Combo). Through utilizing the natural inflammation-homing ability of neutrophil membrane protein and FH peptide's high affinity to tenascin-C (TN-C) produced by CFs, this nanoparticle could realize sequential targeting to CFs in the injured heart and precise intracellular delivery of miRCombo, which induced reprogramming resident CFs into iCMs. In a mouse model of myocardial ischemia/reperfusion injury, intravenous injection of the nanoparticles successfully delivered miRCombo into fibroblasts and led to efficient reprogramming, resulting in improved cardiac function and attenuated fibrosis. This delivery system is minimally invasive and bio-safe, providing a proof-of-concept for biomimetic and sequential targeting nanomedicine delivery system for microRNA-mediated reprogramming therapy in multiple diseases.

Platelet-Like Fusogenic Liposome-Mediated Targeting Delivery of miR-21 Improves Myocardial Remodeling by Reprogramming Macrophages Post Myocardial Ischemia-Reperfusion Injury.

Inflammatory modulations focusing on macrophage phenotype are promising candidates to promote better cardiac healing post myocardial ischemia-reperfusion (MI/R) injury. However, the peak of monocyte/macrophage recruitment is later than the time when enhanced permeability and retention effect disappears, which greatly increases the difficulty of reprogramming macrophages through systemic administration. Meanwhile, the inability of nanomaterials to release their contents to specific intracellular locations through reasonable cellular internalization pathways is another obstacle to achieving macrophage reprogramming. Here, inspired by the increase in circulating platelet-monocyte aggregates in patients' post-MI/R and the high efficiency of fusogenic liposomes to deliver contents to the cytoplasm of target cells, a platelet-like fusogenic liposome (PLPs) is constructed. Under the coating of PLPs, mesoporous silica nanospheres with a payload of miR-21, an anti-inflammatory agent, can be specifically delivered to inflammatory monocytes in the blood circulation of MI/R induced mice. Then it directly enters the cytoplasm of monocytes through membrane fusion, thereby realizing the reparative reprogramming of the inflamed macrophages derived from it. In vivo administration of the resulting formula can effectively preserve the cardiac function of mice undergone MI/R. Minimal invasiveness and biological safety make this nano-platform a promising approach of immunotherapy.

Engineering extracellular vesicles with platelet membranes fusion enhanced targeted therapeutic angiogenesis in a mouse model of myocardial ischemia reperfusion.

Therapeutic angiogenesis is one promising strategy for the treatment of ischemic heart disease, which is the leading cause of death globally. In recent years, extracellular vesicles (EVs) have quickly gained much attention as a cell-free approach to stimulate angiogenesis. However, clinical applications of EVs are limited by their insufficient targeting capability. Herein, we introduce a method to enhance therapeutic angiogenesis based on platelet membrane-engineered EVs. METHODS: Platelet-mimetic EVs (P-EVs) were fabricated by fusing the membranes of EVs with platelet membranes by extrusion. A mouse model of myocardial ischemia reperfusion (MI/R) was established and injected with PBS, EVs, and P-EVs to evaluate their targeting ability and therapeutic angiogenesis efficacy. RESULTS: P-EVs inherited the adhesive proteins and natural targeting ability to injured vasculature of platelets and retained the pro-angiogenic potential of EVs. In the MI/R model, P-EVs preferentially accumulated in the injured endothelium of the ischemic hearts and enhanced the angiogenesis potency of EVs. CONCLUSIONS: This engineering strategy to modify pre-isolated EVs with platelet membranes by membrane fusion bestows EVs with the targeting ability of platelets and offers an exciting opportunity to design other targeted EVs fused with cell membranes from different sources for therapeutic angiogenesis.

Prevalence and Characteristics of Acquired Coronary Fistulas After Successful Revascularization of Chronic Total Occlusion.

Background and Objectives: Acquired coronary fistulas (ACFs) are rare coronary artery abnormalities in patients with chronic total occlusion (CTO). It has been found after revascularization, and it may cause fluster during the CTO percutaneous coronary intervention (CTO PCI). How to distinguish between ACFs and coronary perforation (CP) is very important for CTO operators. Chronic total occlusion reopening may reveal the microchannel of the adventitial vascular layers. Some of ACFs have been seen after revascularization. This study aimed to investigate the characteristics of ACFs after successful CTO PCI. Methods: The clinical and procedural characteristics, medical history, and findings in electrocardiography (ECG), echocardiography, and coronary angiography were collected from 2,169 consecutive patients undergoing CTO PCI between January 2018 and December 2019 and analyzed retrospectively. Results: About 1,844 (85.02%) underwent successful CTO PCI with complete revascularization. Acquired coronary fistulas were found in 49 patients (2.66%): the majority of patients with ACFs were men (81.63 vs. 60.78%; p = 0.016) and younger (62.8 vs. 66.69 years; p = 0.003), and had a history of myocardial infarction (MI) or Q-wave (69.39 vs. 54.21%; p = 0.035); 38 (77.55%) patients had multiple fistulas (≥3), and ACFs affected multiple branches of the CTO vessel (≥3) in 29 (59.18%) patients. None had pericardial effusion, tamponade, and hemodynamic abnormality before or after PCI. Conclusion: Acquired coronary fistulas after successful CTO PCI are mainly present in young and male patients with a history of MI, and they often involve multiple fistulas and distal CTO vessels.

Monocyte mimics improve mesenchymal stem cell-derived extracellular vesicle homing in a mouse MI/RI model.

Stem cell-derived extracellular vesicles (EVs) have been demonstrated to be effective in heart repair and regeneration post infarction. However, the poor homing efficiency and low yields of these therapeutics remain the major obstacles before they can be used in the clinic. To improve the delivery efficiency of EVs to ischemia-injured myocardium, we modified mesenchymal stem cell (MSC)-derived EVs with monocyte mimics through the method of membrane fusion. Monocyte mimic-bioinspired MSC-EVs (Mon-Exos) exhibited enhanced targeting efficiency to injured myocardium by mimicking the recruitment feature of monocytes after MI/RI, thus contributing to these exclusive adhesive molecules on monocyte mimics, particularly the Mac1/LFA1-ICAM-1 interaction. Through this strategy, Mon-Exos were shown to promote endothelial maturation during angiogenesis and modulate macrophage subpopulations after MI/RI, consistent with MSC-Exos biofunctions, and eventually improve therapeutic outcomes in cardiac function and pathohistology changes after treatments in a mouse MI/RI model. Ultimately, this strategy might provide us with a better way to assess the effects of stem cell EVs and offer additional techniques to help clinicians better manage regenerative therapeutics for ischemic heart diseases.