The influence of microenvironment stiffness on endothelial cell fate: Implication for occurrence and progression of atherosclerosis

Biomimetic 3D bioprinted bilayer GelMA scaffolds for the delivery of BMP-2 and VEGF exogenous growth factors to promote vascularized bone regeneration in a calvarial defect model in vivo

The effective treatment of critical-sized bone defects requires a coordinated interaction between osteogenesis and angiogenesis. Inspired by natural bone tissue, we developed a bilayer vascularized bone construct using extrusion-based dual 3D bioprinting. The construct consists of two layers: a bone-mimetic layer, which includes highly methacrylated gelatin (GelMAHIGH), hyaluronic acid, alginate, osteoblast cells, and bone morphogenetic protein-2 (BMP-2) loaded polylactic-co-glycolic acid (PLGA) nanoparticles; and a vessel-mimetic layer, composed of low methacrylated gelatin (GelMALOW), alginate, endothelial cells, and vascular endothelial growth factor (VEGF)-loaded PLGA nanoparticles. These layers were designed to form hierarchical microstructures that enable sustained release of growth factor (GF) thereby stimulating both osteogenic and angiogenic processes. The nanoparticles were synthesized using a microfluidic platform, achieving a narrow size distribution. The hydrogel bioinks were systematically optimized for printability, and it was found that incorporation of nanoparticles improved their mechanical properties, surface roughness, degradability, and GF release profiles. Notably, GF release followed zero-order kinetics, ensuring consistent delivery over time. The bilayer scaffolds demonstrated superior cell proliferation and spreading compared to single-layer scaffolds, and in vivo experiments showed enhanced repair of calvarial bone defects. These findings highlight the significant clinical potential of bilayer scaffolds with sequential GF delivery for treating critical-sized bone defects.

Studying biological events using biopolymeric matrices

Traditional methodologies to study in vitro biological processes include simplified laboratory models where different parameters can be measured in a very controlled environment. The most used of these practices is cell plate-culturing in aqueous media. In this minimalistic model, essential components of the biological system might be ignored. One of them, disregarded for a long time, is the extracellular matrix (ECM). Extracellular matrix in eukaryotic cells is not only a frame for cells and biological components, but also an active partner of cellular metabolism and participates in several normal and pathological biological processes in a dynamic manner. ECM of eukaryotic cells has a very complex structure. Also, its mechanical properties (stiffness, viscoelasticity) depend on the organ it is associated with, and may vary from a very fluid (plasma) to a very solid (bones) structure. ECM structure and composition are very dynamic and experience temporal structural and topological changes, affecting all the existing interactions. When mimicking the ECM, three aspects are considered: the chemical environment and the physical and structural properties. In this review, we present two lines of research studying the role of the ECM in two biological implications: membrane fluidity heterogeneity and protein retention and aggregation. For these studies, we used biopolymeric matrices with very controlled features to evaluate the two events. We use traditional biochemical techniques and fluorescence microscopy to study the biological systems and traditional polymer techniques (rheology, SEM) to characterize the polymeric matrices.

Microneedles Loaded with Nitric-Oxide Driven Nanomotors Improve Force-Induced Efferocytosis Impairment and Sterile Inflammation by Revitalizing Macrophage Energy Metabolism

Mechanical force initiates sterile inflammation, a process implicated in diverse physiological and pathological processes. The timely clearance of apoptotic cells by macrophages via efferocytosis is crucial for the proper resolution of sterile inflammation and for averting excessive tissue damage. Despite this, the specific role and underlying mechanisms of mechanical force on macrophage efferocytosis remain obscure. By integrating bioinformatics and metabolomics analyses, we uncovered how mechanical force disrupts the "arginine metabolism─TCA cycle─mitochondrial function" metabolic cascade, thereby impairing macrophage efferocytosis and intensifying sterile inflammation. Notably, we discovered that elevating l-arginine levels can ameliorate these crises by restoring energy metabolism. Leveraging this insight, we engineered a microneedle drug delivery system loaded with nitric-oxide driven nanomotors (MSN-LA@MNs) for targeted delivery of l-arginine. The active component, MSN-LA, exploits the heightened expression of inducible nitric oxide synthase (iNOS) in force-loaded tissues as a chemoattractant, harnessing NO generated from iNOS-catalyzed l-arginine for autonomous propulsion. In a force-induced rat orthodontic tooth movement (OTM) model, we confirmed that MSN-LA@MNs enhance macrophage efferocytosis and, under iNOS guidance, dynamically modulate sterile inflammation levels in OTM, thus facilitating the OTM process. Collectively, our findings elucidate previously unclear mechanistic links between force, macrophage efferocytosis, and sterile inflammation from a metabolic vantage point, offering a promising targeted strategy for modulating force-related biological processes such as OTM.

Angiogenesis within atherosclerotic plaques: Mechanical regulation, molecular mechanism and clinical diagnosis

Atherosclerosis (AS) is a disease characterized by focal cholesterol accumulation and insoluble inflammation in arterial intima, leading to the formation of an atherosclerotic plaque consisting of lipids, cells, and fibrous matrix. The presence of plaque can restrict or obstruct blood flow, resulting in arterial stenosis and local mechanical microenvironment changes including flow shear stress, vascular matrix stiffness, and plaque structural stress. Neovascularization within the atherosclerotic plaque plays a crucial role in both plaque growth and destabilization, potentially leading to plaque rupture and fatal embolism. However, the exact interactions between neovessels and plaque remain unclear. In this review, we provide a comprehensive analysis of the origin of intraplaque neovessels, the contributing factors, underlying molecular mechanisms, and associated signaling pathways. We specifically emphasize the role of mechanical factors contributing to angiogenesis in atherosclerotic plaques. Additionally, we summarize the imaging techniques and therapeutic strategies for intraplaque neovessels to enhance our understanding of this field.

SAL protects endothelial cells from H2O2-induced endothelial dysfunction: Regulation of inflammation and autophagy by EZH2

One component of the polycomb repressor complex 2 is histone methyltransferase zeste homolog 2 (EZH2), which is also called Enhancer of zeste homolog 2. It is considered a potential therapeutic target for inhibiting endothelial dysfunction.. Hence, directing efforts towards EZH2 to weaken endothelium damage and regulate vascular lesions proves to be a highly successful therapeutic approach for enhancing endothelial dysfunction. This study aimed to investigate the mechanism by which salidroside (SAL) improves hydrogen peroxide (H2O2)-induced endothelial dysfunction. The investigation involved the use of many techniques, including western blotting, real-time polymerase chain reaction (RT-PCR), a scratch test, molecular docking, and other methods. The experimental findings demonstrated that SAL has the ability to inhibit the impaired functioning of endothelial cells caused by H2O2 and decrease the levels of NF-κB p65, NLRP3, TNF-α, Beclin1, LC3, and P62 proteins. Additionally, there seems to be a targeting relationship between SAL and EZH2, and EZH2 knockdown can reproduce the protective effect of SAL on endothelial function. Overall, SAL inhibits H2O2-induced HUVEC dysfunction by regulating autophagy and inflammatory signaling pathways through EZH2.

Coronary Spasm Due to Pulsed Field Ablation: A State-of-the-Art Review

With the ever-growing population of patients undergoing cardiac ablation with pulsed electric fields, there is a need to understand secondary effects from the therapy. Coronary artery spasm is one such effect that has recently emerged as the subject of further investigation in electrophysiology literature. This review aims to elucidate the basic anatomy underlying vascular spasm due to pulsed electric fields and the effects of irreversible electroporation on coronary arteries. This review also aims to gather the current preclinical and clinical data regarding the physiology and function of coronary arteries following electroporation.

ECM Microenvironment in Vascular Homeostasis: New Targets for Atherosclerosis

Alterations in vascular extracellular matrix (ECM) components, interactions, and mechanical properties influence both the formation and stability of atherosclerotic plaques. This review discusses the contribution of the ECM microenvironment in vascular homeostasis and remodeling in atherosclerosis, highlighting Cartilage oligomeric matrix protein (COMP) and its degrading enzyme ADAMTS7 as examples, and proposes potential avenues for future research aimed at identifying novel therapeutic targets for atherosclerosis based on the ECM microenvironment.

Remodelers of the vascular microenvironment: The effect of biopolymeric hydrogels on vascular diseases

Vascular disease is the leading health problem worldwide. Vascular microenvironment encompasses diverse cell types, including those within the vascular wall, blood cells, stromal cells, and immune cells. Initiation of the inflammatory state of the vascular microenvironment and changes in its mechanics can profoundly affect vascular homeostasis. Biomedical materials play a crucial role in modern medicine, hydrogels, characterized by their high-water content, have been increasingly utilized as a three-dimensional interaction network. In recent times, the remarkable progress in utilizing hydrogels and understanding vascular microenvironment have enabled the treatment of vascular diseases. In this review, we give an emphasis on the utilization of hydrogels and their advantages in the various vascular diseases including atherosclerosis, aneurysm, vascular ulcers of the lower limbs and myocardial infarction. Further, we highlight the importance and advantages of hydrogels as artificial microenvironments.

Shear Stress and Endothelial Mechanotransduction in Trauma Patients with Hemorrhagic Shock: Hidden Coagulopathy Pathways and Novel Therapeutic Strategies

Massive trauma remains a leading cause of death and a global public health burden. Post-traumatic coagulopathy may be present even before the onset of resuscitation, and correlates with severity of trauma. Several mechanisms have been proposed to explain the development of abnormal coagulation processes, but the heterogeneity in injuries and patient profiles makes it difficult to define a dominant mechanism. Regardless of the pattern of death, a significant role in the pathophysiology and pathogenesis of coagulopathy may be attributed to the exposure of endothelial cells to abnormal physical forces and mechanical stimuli in their local environment. In these conditions, the cellular responses are translated into biochemical signals that induce/aggravate oxidative stress, inflammation, and coagulopathy. Microvascular shear stress-induced alterations could be treated or prevented by the development and use of innovative pharmacologic strategies that effectively target shear-mediated endothelial dysfunction, including shear-responsive drug delivery systems and novel antioxidants, and by targeting the venous side of the circulation to exploit the beneficial antithrombogenic profile of venous endothelial cells.