Fibrosis is characterized by the excessive deposition of extracellular matrix and crosslinked proteins, in particular collagen and elastin, leading to tissue stiffening and disrupted organ function. ...Lysyl oxidases are key players during this process, as they initiate collagen crosslinking through the oxidation of the ε‐amino group of lysine or hydroxylysine on collagen side‐chains, which subsequently dimerize to form immature, or trimerize to form mature, collagen crosslinks. The role of LOXL2 in fibrosis and cancer is well documented, however the specific enzymatic function of LOXL2 and LOXL3 during disease is less clear. Herein, we describe the development of PXS‐5153A, a novel mechanism based, fast‐acting, dual LOXL2/LOXL3 inhibitor, which was used to interrogate the role of these enzymes in models of collagen crosslinking and fibrosis. PXS‐5153A dose‐dependently reduced LOXL2‐mediated collagen oxidation and collagen crosslinking in vitro. In two liver fibrosis models, carbon tetrachloride or streptozotocin/high fat diet‐induced, PXS‐5153A reduced disease severity and improved liver function by diminishing collagen content and collagen crosslinks. In myocardial infarction, PXS‐5153A improved cardiac output. Taken together these results demonstrate that, due to their crucial role in collagen crosslinking, inhibition of the enzymatic activities of LOXL2/LOXL3 represents an innovative therapeutic approach for the treatment of fibrosis.
Despite its growing importance in biology and in biomaterials development, liquid–liquid phase separation of proteins remains poorly understood. In particular, the molecular mechanisms underlying ...simple coacervation of proteins, such as the extracellular matrix protein elastin, have not been reported. Coacervation of the elastin monomer, tropoelastin, in response to heat and salt is a critical step in the assembly of elastic fibers in vivo, preceding chemical cross-linking. Elastin-like polypeptides (ELPs) derived from the tropoelastin sequence have been shown to undergo a similar phase separation, allowing formation of biomaterials that closely mimic the material properties of native elastin. We have used NMR spectroscopy to obtain site-specific structure and dynamics of a self-assembling elastin-like polypeptide along its entire self-assembly pathway, from monomer through coacervation and into a cross-linked elastic material. Our data reveal that elastin-like hydrophobic domains are composed of transient β-turns in a highly dynamic and disordered chain, and that this disorder is retained both after phase separation and in elastic materials. Cross-linking domains are also highly disordered in monomeric and coacervated ELP₃ and form stable helices only after chemical cross-linking. Detailed structural analysis combined with dynamic measurements from NMR relaxation and diffusion data provides direct evidence for an entropy-driven mechanism of simple coacervation of a protein in which transient and nonspecific intermolecular hydrophobic contacts are formed by disordered chains, whereas bulk water and salt are excluded.
Heart valve tissue engineering (HVTE) aims to provide living autologous heart valve implants endowed with regenerative capabilities and life‐long durability. However, fabrication of biomimetic ...scaffolds capable of providing the required functionality in terms of mechanical performance and tunable porosity to enable cellular infiltration remains a major challenge. Here, the additive manufacturing of bioinspired, spatially heterogeneous, tubular scaffolds enclosing the leaflets, inter‐leaflet triangles, and their interface for in situ HVTE using melt electrowriting (MEW) is demonstrated. The innovative platform enables the digital fabrication of scaffolds with ad hoc architecture (e.g., tunable location, specific fiber pattern, and orientation) and customizable geometry via a custom‐made control software. The user‐friendly interface allows for the definition of areas of the scaffold with specific patterns to obtain properties such as tunable J‐shaped stress–stain curve and anisotropy typical of the heart valve leaflet, compliant inter‐leaflet triangles, and reinforced curvilinear boundary between them. Heterogeneous, tubular, heart valve MEW scaffolds are then embedded with a microporous elastin‐like recombinamer (ELR) hydrogel to develop a soft‐network composite favoring cell infiltration and ensuring hemocompatibility. The acute systolic hemodynamic functionality of the MEW/ELR composite satisfies the ISO 5840 requirements, under aortic and pulmonary conditions.
The convergence of melt electrowriting, as advanced additive manufacturing technology, and elastin‐like recombinamers, as advanced bioactive materials, results in a versatile platform for the digital fabrication of bio‐inspired, spatially heterogeneous scaffolds for in situ heart valve tissue engineering, with low thrombogenicity and tuned porosity for cellular infiltration. This platform can be extended to other soft tissue engineering applications.
Aortic disease is a significant cause of death in developed countries. The most common forms of aortic disease are aneurysm, dissection, atherosclerotic occlusion and ageing-induced stiffening. The ...microstructure of the aortic tissue has been studied with great interest, because alteration of the quantity and/or architecture of the connective fibres (elastin and collagen) within the aortic wall, which directly imparts elasticity and strength, can lead to the mechanical and functional changes associated with these conditions. This review article summarizes the state of the art with respect to characterization of connective fibre microstructure in the wall of the human aorta in ageing and disease, with emphasis on the ascending thoracic aorta and abdominal aorta where the most common forms of aortic disease tend to occur.
Fibrillin microfibrils are extensible polymers that endow connective tissues with long-range elasticity and have widespread distributions in both elastic and non-elastic tissues. They act as a ...template for elastin deposition during elastic fibre formation and are essential for maintaining the integrity of tissues such as blood vessels, lung, skin and ocular ligaments. A reduction in fibrillin is seen in tissues in vascular ageing, chronic obstructive pulmonary disease, skin ageing and UV induced skin damage, and age-related vision deterioration. Most mutations in fibrillin cause Marfan syndrome, a genetic disease characterised by overgrowth of the long bones and other skeletal abnormalities with cardiovascular and eye defects. However, mutations in fibrillin and fibrillin-binding proteins can also cause short-stature pathologies. All of these diseases have been linked to dysregulated growth factor signalling which forms a major functional role for fibrillin.
In recent years, antimicrobial peptides (AMPs) have become a promising alternative to the use of conventional and chemically synthesized antibiotics, especially after the emergence of ...multidrug‐resistant organisms. Thus, this review aims to provide an updated overview of the state‐of‐the‐art for producing antimicrobial peptides fused or conjugated with the elastin‐like (ELP) peculiar carriers, and that are mostly intended for biomedical application. The elastin‐like biopolymers are thermosensitive proteins with unique properties. Due to the flexibility of their modular structure, their features can be tuned and customized to improve the production of the antimicrobial domain while reducing their toxic effects on the host cells. Both fields of research faced a huge rise in interest in the last decade, as witnessed by the increasing number of publications on these topics, and several recombinant fusion proteins made of these two domains have been already described but they still present a limited variability. Herein, the approaches described to recombinantly fuse and chemically conjugate diverse AMPs with ELPs are reviewed, and the nature of the AMPs and the ELPs used, as well as the main features of the expression and production systems are summarized.
Bioinspired actuators with stimuli-responsive and deformable properties are being pursued in fields such as artificial tissues, medical devices and diagnostics, and intelligent biosensors. These ...applications require that actuator systems have biocompatibility, controlled deformability, biodegradability, mechanical durability, and stable reversibility. Herein, we report a bionic actuator system consisting of stimuli-responsive genetically engineered silk–elastin-like protein (SELP) hydrogels and wood-derived cellulose nanofibers (CNFs), which respond to temperature and ionic strength underwater by ecofriendly methods. Programmed site-selective actuation can be predicted and folded into three-dimensional (3D) origami-like shapes. The reversible deformation performance of the SELP/CNF actuators was quantified, and complex spatial transformations of multilayer actuators were demonstrated, including a biomimetic flower design with selective petal movements. Such actuators consisting entirely of biocompatible and biodegradable materials will offer an option toward constructing stimuli-responsive systems for in vivo biomedicine soft robotics and bionic research.
Spatiotemporal control of vascularization and innervation is a desired hallmark in advanced tissue regeneration. For this purpose, we design a 3D model scaffold, based on elastin‐like recombinamer ...(ELR) hydrogels. This contains two interior and well‐defined areas, small cylinders, with differentiated bioactivities with respect to the bulk. Both are constructed on a protease sensitive ELR with a fast‐proteolyzed domain, but one bears a VEGF‐mimetic peptide (QK) and the other a laminin‐derived pentapeptide (IKVAV), to promote angiogenesis and neurogenesis, respectively. The outer bulk is based on a slow proteolytic sequence and RGD cell adhesion domains. In vitro studies show the effect of QK and IKVAV peptides on the promotion of endothelial cell and axon spreading, respectively. The subcutaneous implantation of the final 3D scaffold demonstrates the ability to spatiotemporally control angiogenesis and neurogenesis in vivo. Specifically, the inner small cylinder containing the QK peptide promotes fast endothelialization, whereas the one with IKVAV peptide promotes fast neurogenesis. Both, vascularization and innervation take place in advance of the bulk scaffold infiltration. This scaffold shows that it is possible to induce vascularization and innervation in predetermined areas of the scaffold well ahead to the bulk infiltration. That significantly increases the efficiency of the regenerative activity.
Herein, a 3D model scaffold containing two cylindrical elastin‐like recombinamer (ELR) hydrogels embedded in a slow‐resorbable or nonprotease‐sensitive ELR hydrogel that allow the independent spatiotemporal control of angiogenesis and neurogenesis in vivo, by the combination of protease‐sensitive sequences, with fast and slow degradation kinetics, a VEGF‐mimetic peptide (QK), and a laminin‐derived peptide (IKVAV) is developed.
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•Genetically engineered nanoparticles enable significant advances in drug delivery.•Recombinant synthesis allows for creation of novel morphologies.•Self-assembly of nanostructures ...enhances drug loading and delivery strategies.•ELP nanoparticles represent a promising horizon for future therapeutics.
Small molecule drugs suffer from poor in vivo half-life, rapid degradation, and systemic off-target toxicity. To address these issues, researchers have developed nanoparticles that significantly enhance the delivery of many drugs while reducing their toxicity and improving targeting to specific organs. Recombinantly synthesized biomaterials such as elastin-like polypeptides (ELPs) have unique attributes that greatly facilitate the rational design of nanoparticles for drug delivery. These attributes include biocompatibility, precise control over amino acid sequence design, and stimuli-responsive self-assembly into nanostructures that can be loaded with a range of drugs to enhance their pharmacokinetics and pharmacodynamics, significantly improving their therapeutic efficacy over the free drugs. This review summarizes recent developments in genetically encoded, self-assembling ELP nanoparticles and their applications for drug delivery.
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