Recent advances to accelerate re-endothelialization for vascular stents

Liver tissue engineering using decellularized scaffolds: Current progress, challenges, and opportunities

Liver transplantation represents the only definitive treatment for patients with end-stage liver disease. However, the shortage of liver donors provokes a dramatic gap between available grafts and patients on the waiting list. Whole liver bioengineering, an emerging field of tissue engineering, holds great potential to overcome this gap. This approach involves two main steps; the first is liver decellularization and the second is recellularization. Liver decellularization aims to remove cellular and nuclear materials from the organ, leaving behind extracellular matrices containing different structural proteins and growth factors while retaining both the vascular and biliary networks. Recellularization involves repopulating the decellularized liver with appropriate cells, theoretically from the recipient patient, to reconstruct the parenchyma, vascular tree, and biliary network. The aim of this review is to identify the major advances in decellularization and recellularization strategies and investigate obstacles for the clinical application of bioengineered liver, including immunogenicity of the designed liver extracellular matrices, the need for standardization of scaffold fabrication techniques, selection of suitable cell sources for parenchymal repopulation, vascular, and biliary tree reconstruction. In vivo transplantation models are also summarized for evaluating the functionality of bioengineered livers. Finally, the regulatory measures and future directions for confirming the safety and efficacy of bioengineered liver are also discussed. Addressing these challenges in whole liver bioengineering may offer new solutions to meet the demand for liver transplantation and improve patient outcomes.

Meta-long Papyrus: Meta-analysis of mid to long-term outcomes of PK Papyrus covered stent

BACKGROUND

Although covered stents (CS) represent a potentially life-saving intervention for coronary perforation (CAP), their application has expanded to other contexts, including coronary aneurysms (CAA). However, data regarding mid- and long-term outcomes of CS in these settings scenarios remains limited.

AIMS

This meta-analysis aims to evaluate major adverse cardiac events (MACE) from discharge through long-term follow-up in patients undergoing percutaneous coronary intervention with the new generation polyurethane-covered cobalt-chromium PK Papyrus CS.

METHODS

We conducted a meta-analysis of data from three observational trials that included long-term follow-up of patients who underwent PK Papyrus CS implantation: Papyrus-Spain, SOS PK Papyrus, and PAST-PERF registry.

RESULTS

332 patients underwent PK Papyrus CS implantation, 236 (71.1%) for CAP, 70 (21.1%) for CAA and 26 (7.8%) for other indications. After a mean follow-up of 16.2 months, the MACE was 14.3%, with Target Lesion Revascularization (TLR) being the most frequent (8.5%), followed by stent thrombosis (ST), 3.3% and cardiac death (CD), 2.6%. Comparing CAP and CAA subgroups, the MACE rate in CAA was significantly higher than CAP (21.4% vs 9.7%, p < 0.01), primary driven by ST (CAA: 8.6% vs CAP: 1.3%; p = 0.0015).

CONCLUSIONS

The clinical outcomes following PK Papyrus CS implantation are deemed acceptable, considering the challenging scenarios and the existing alternative treatments. However, MACE rates in patients with CAA who received Papyrus PK CS were significantly higher than in those with CAP, underscoring the importance of meticulous patient selection and optimization of CS in these complex patients and coronary anatomies.

Longitudinal healing flow diverting stents with phosphorylcholine surface modification

BACKGROUND

Flow diversion has become a standard treatment for cerebral aneurysms. However, major drawbacks include the need for dual antiplatelet therapy after implant and delayed complete occlusion of the aneurysm, which occurs when new tissue growth excludes the aneurysm from the parent artery. Biomimetic surface modifications such as the phosphorylcholine polymer (Shield surface modification) represent major advances in reducing thrombogenicity of these devices. However, in vitro studies have raised concerns that this modification may also delay endothelialization of flow diverters.

METHODS

Bare metal Pipeline, Pipeline Shield, and Vantage with Shield devices were implanted in the common carotid arteries (CCAs) of 10 rabbits (two in the left CCA, one in the right CCA). Following implant and at 5, 10, 15, and 30 days, the devices were imaged with high-frequency optical coherence tomography and conventional angiography to evaluate tissue growth. At 30 days the devices were explanted and their endothelial growth was assessed with scanning electron microscopy (SEM) at five locations along their length using a semi-quantitative score.

RESULTS

The average tissue growth thickness (ATGT) was not different between the three devices. Neointima was apparent at 5 days and all devices demonstrated similar ATGT at each time point. On SEM, no difference was found in the endothelium scores between the device types.

CONCLUSION

In vivo, neither the Shield surface modification nor the device design (Vantage) altered the longitudinal healing of the flow diverter.

3D-Printed Shape Memory Poly(alkylene terephthalate) Scaffolds as Cardiovascular Stents Revealing Enhanced Endothelialization

Cardiovascular diseases are the leading cause of death and current treatments such as stents still suffer from disadvantages. Balloon expansion causes damage to the arterial wall and limited and delayed endothelialization gives rise to restenosis and thrombosis. New more performing materials that circumvent these disadvantages are required to improve the success rate of interventions. To this end, the use of a novel polymer, poly(hexamethylene terephthalate), is investigated for this application. The synthesis to obtain polymers with high molar masses up to 126.5 kg mol-1 is optimized and a thorough chemical and thermal analysis is performed. The polymers are 3D-printed into personalized cardiovascular stents using the state-of-the-art solvent-cast direct-writing technique, the potential of these stents to expand using their shape memory behavior is established, and it is shown that the stents are more resistant to compression than the poly(l-lactide) benchmark. Furthermore, the polymer's hydrolytic stability is demonstrated in an accelerated degradation study of 6 months. Finally, the stents are subjected to an in vitro biological evaluation, revealing that the polymer is non-hemolytic and supports significant endothelialization after only 7 days, demonstrating the enormous potential of these polymers to serve cardiovascular applications.

In-silico study of drug delivery to atherosclerosis in the human carotid artery using metal-organic frameworks based on adhesion of nanocarriers

This study investigates nanocarriers (NCs) for drug delivery targeting carotid artery atherosclerosis. This targeted drug delivery mechanism is based on ligand-receptor bindings facilitated by coating NCs with P-selectin aptamers, which exhibit high affinities for P-selectin plaque receptors. Recognizing the significant advantages of metal-organic frameworks (MOFs), such as their high drug-loading percentages, we chose them as nanocarriers for this research. Our evaluation considers critical factors: NC surface density (the number of attached nanocarriers per unit of plaque area), toxicity (percentage of NCs missing the target), and efficient drug transfer to plaque tissue. Employing molecular dynamics (MD) for drug loading calculations via van der Waals interactions and computational fluid dynamics (CFD) for toxicity, surface density, and drug transfer assessments, we achieve a comprehensive analysis. A cardiac cycle-based metric guides optimal MOF release conditions, establishing an ideal dosage of 600 NCs per cycle. MOF-801 exhibits outstanding drug delivery performance, particularly in plaque targeting. While a magnetic field enhances NC adhesion, its impact on drug transfer is limited, emphasizing the need for further optimization in magnetic targeting for NC-based therapies. This study provides crucial insights into NC drug delivery performance in carotid artery atherosclerosis, advancing the field of targeted drug delivery for atherosclerosis treatment.

Shape Memory Polymer Composites: 4D Printing, Smart Structures, and Applications

Shape memory polymers (SMPs) and their composites (SMPCs) are smart materials that can be stably deformed and then return to their original shape under external stimulation, thus having a memory of their shape. Three-dimensional (3D) printing is an advanced technology for fabricating products using a digital software tool. Four-dimensional (4D) printing is a new generation of additive manufacturing technology that combines shape memory materials and 3D printing technology. Currently, 4D-printed SMPs and SMPCs are gaining considerable research attention and are finding use in various fields, including biomedical science. This review introduces SMPs, SMPCs, and 4D printing technologies, highlighting several special 4D-printed structures. It summarizes the recent research progress of 4D-printed SMPs and SMPCs in various fields, with particular emphasis on biomedical applications. Additionally, it presents an overview of the challenges and development prospects of 4D-printed SMPs and SMPCs and provides a preliminary discussion and useful reference for the research and application of 4D-printed SMPs and SMPCs.

Postfunctionalization of biological valve leaflets with a polyphenol network and anticoagulant recombinant humanized type III collagen for improved anticoagulation and endothelialization

Almost all commercial bioprosthetic heart valves (BHVs) are crosslinked with glutaraldehyde (GLUT); however, issues such as immune responses, calcification, delayed endothelialization, and especially severe thrombosis threaten the service lifespan of BHVs. Surface modification is expected to impart GLUT-crosslinked BHVs with versatility to optimize service performance. Here, a postfunctionalization strategy was established for GLUT-crosslinked BHVs, which were firstly modified with metal-phenolic networks (MPNs) to shield the exposed calcification site, and then anticoagulant recombinant humanized type III collagen (rhCOLIII) was immobilized to endow them with long-term antithrombogenicity and enhanced endothelialization properties. The postfunctionalization coating exhibited promising mechanical properties and resistance to enzymatic degradation capability resembling that of GLUT-crosslinked porcine pericardium (GLUT-PP). With the introduction of meticulously tailored rhCOLIII, the anti-coagulation and re-endothelialization properties of TA/Fe-rhCOLIII were significantly improved. Furthermore, the mild inflammatory response and reduced calcification were evidenced in TA/Fe-rhCOLIII by subcutaneous implantation. In conclusion, the efficacy of the proposed strategy combining anti-inflammatory MPNs and multifunctional rhCOLIII to improve anticoagulation, reduce the inflammatory response, and ultimately achieve rapid reendothelialization was supported by both ex vivo and in vivo experiments. Altogether, the current findings may provide a simple strategy for enhancing the service function of BHVs after implantation and show great potential in clinical applications.

Poly(2-methoxyethyl acrylate) (PMEA) improves the thromboresistance of FRED flow diverters: a thrombogenic evaluation of flow diverters with human blood under flow conditions

BACKGROUND

Surface modification of flow-diverting stents has been explored to reduce thrombus-related complications that may arise under clinical use. This study investigated the thromboresistant properties of the flow redirection endoluminal device (FRED) X, a flow diverter treated with a copolymer of poly(2-methoxyethyl acrylate) (PMEA; X Technology).

METHODS

The performance of FRED, FRED X, and Pipeline Flex with Shield Technology (sPED) was evaluated in an in vitro blood loop model. Blood activation level was assessed by the concentration of thrombin-antithrombin complex (TAT), β-thromboglobulin (β-TG), and platelet count, and qualitatively by scanning electron microscopy (SEM). Cellular adhesion characteristics were measured using human aortic endothelial cells that were seeded on flat sheets mimicking the surface of FRED, FRED X, and sPED, and evaluated with fluorescence microscopy. Statistical comparisons were conducted using one-way analysis of variance (ANOVA) with Tukey post hoc tests.

RESULTS

FRED X, sPED, and control blood loops showed significantly reduced blood activation levels (TAT and β-TG) compared with FRED (p<0.01). Consequently, FRED showed a significant decrease in platelet count compared with FRED X, sPED, and control loops (p<0.01). SEM imaging showed the lowest accumulation of blood cell-like deposits on FRED X compared with sPED and FRED, while FRED had the highest accumulation. Endothelial cells adhered and were widely spread on X Technology-treated sheets, while minimal cell adhesion was observed on phosphorylcholine-treated sheets.

CONCLUSION

The X Technology surface modification of FRED X demonstrated superior thromboresistant properties over untreated FRED while maintaining comparable cellular adhesion. Taken together, these properties may help mitigate material-related thromboembolic complications.

Paeonol Promotes Reendothelialization After Vascular Injury Through Activation of c-Myc/VEGFR2 Signaling Pathway

Purpose

Dysfunction of endothelium is associated with multiple pathological vascular diseases. However, how to regulate reendothelialization after vascular injury is not well defined. This study aims to determine whether and how Paeonol controls reendothelialization following artery injury.

Methods

The endothelium of murine carotid artery was denuded by catheter guide wires injury. H&E staining and IF staining were performed to determine whether Paeonol is critical for reendothelialization. BRDU Incorporation Assay, Boyden Chamber Migration Assay, Tube Formation Assay, and Spheroid Sprouting Assay were used to investigate whether Paeonol is involved in regulating proliferation and migration of endothelial cells. The underlying mechanism of how Paeonol regulates reendothelialization was determined by Molecular docking simulation and CO-IP Assay.

Results

Paeonol treatment significantly inhibits neointima formation in carotid artery ligation model by promoting proliferation and migration of endothelial cells. Mechanistically, Paeonol enhances c-Myc expression, consequently interacts with VEGFR2 results in activating VEGF signaling pathway, and eventually promotes reendothelialization after vascular injury.

Conclusion

Our data demonstrated that Paeonol plays a critical role in regulating vascular reendothelialization, which may be therapeutically used for treatment of pathological vascular diseases.

Multimodal effects of asymmetric coating of coronary stents by electrospinning and electrophoretic deposition

Drug-eluting stents (DESs) are drug-coated vascular implants that inhibit smooth muscle cell proliferation and limit in-stent re-stenosis. However, traditional DESs release a single drug into the blood and cannot cope with complex mechanisms in atherosclerosis and body responses. The present study aimed to develop a novel multimodal stent by fabricating asymmetric coating with electrophoretic deposition and electrospinning. Herein, we use heparin-loaded alginate (Hep/Alg) and atorvastatin calcium-loaded polyurethane (AtvCa/PU) coatings on the stent luminal and abluminal surfaces, respectively. Scanning electron microscopy (SEM) micrographs showed that the alginate coatings had uniformity and thin thickness. Meanwhile, the PU fibers were formed without beads, with an acceptable diameter and suitable mechanical properties. PU nanofiber revealed minimal degradation in a 1-month study. The release of AtvCa and Hep continued for 8 days without a significant initial burst release. None of the stent coatings were cytotoxic or hemolytic, and PU nanofibers supported the survival of human umbilical endothelial cells (HUVEC) with high adhesion and flattened morphologies. The results indicate that electrophoretic deposition and electrospinning have significant potential for achieving asymmetric coating on stents and a promising approach for dual drug release for multimodal effects in vascular stent applications.

Artificial Extracellular Matrix Composed of Heparin-Mimicking Polymers for Efficient Anticoagulation and Promotion of Endothelial Cell Proliferation

Heparin-mimicking polymers have emerged as an alternative to heparin to construct effective and safe anticoagulant surfaces. However, the present heparin-mimicking polymers are usually limited to the combinations of glucose and sulfonic acid units, and the structure origin of their anticoagulant properties remains vague. Inspired by the structure of natural heparin, we synthesized a series of novel heparin-mimicking polymers (named GSAs) composed of three units, glucose, sulfonic acid, and carboxylic acid. Then, we constructed artificial extracellular matrices composed of GSAs and two typical cationic polymers, polyethyleneimine and chitosan, to investigate the anticoagulation and endothelialization of GSAs. By changing the ratio of the three units, their functions in the matrices were studied systematically. We found that an increase in the sulfonic acid content enhanced surface anticoagulant activity, an increase in glucose and sulfonic acid content promoted the proliferation of human umbilical vein vascular endothelial cells, and an increase in the carboxylic acid content inhibited the adherence of human umbilical vein vascular smooth muscle cells. This work uncovers the important role of the GSAs structure to the anticoagulation properties, which sheds new light on the design and preparation of heparin-mimicking polymers for practical engineering applications.

The path to a hemocompatible cardiovascular implant: Advances and challenges of current endothelialization strategies

Cardiovascular (CV) implants are still associated with thrombogenicity due to insufficient hemocompatibility. Endothelialization of their luminal surface is a promising strategy to increase their hemocompatibility. In this review, we provide a collection of research studies and review articles aiming to summarize the recent efforts on surface modifications of CV implants, including stents, grafts, valves, and ventricular assist devises. We focus in particular on the implementation of micrometer or nanoscale surface modifications, physical characteristics of known biomaterials (such as wetness and stiffness), and surface morphological features (such as gratings, fibers, pores, and pits). We also review how biomechanical signals originating from the endothelial cell for surface interaction can be directed by topography engineering approaches toward the survival of the endothelium and its long-term adaptation. Finally, we summarize the regulatory and economic challenges that may prevent clinical implementation of endothelialized CV implants.

Topography Control of Micro-Nanosized Anatase Coating on Magnesium Alloy

Constructing surface topographies in the micro- or nanometer range is an effective way to improve the biocompatibility of biomaterials. For the present work, anatase coatings with controllable micro/nanoscale characteristics were successfully prepared on an MgZn alloy surface via solvothermal route, and their formation mechanisms are discussed. The features of the as-prepared coatings were characterized using a scanning electron microscope (SEM), a transmission electron microscope (TEM), an atomic force microscope (AFM), X-ray diffraction (XRD), and a contact angle goniometer. The corrosion behavior of the coatings was also evaluated by testing the open circuit potential (OCP) in SBF (Simulated Body Fluid). The results show that a gradual variation of the anatase coating morphologies was obtained through adjusting the solvothermal reaction conditions. With the increase of NH4F concentration in the solution, the cross-combined anatase nanosheets became more dispersed. The micro/nanostructured anatase coatings provide the MgZn alloy with good corrosion resistance, which increased with the density of anatase nanosheets in the coatings. In addition, the coatings exhibit the inhibition of platelet aggregation, and the micro/nano structures can also adsorb endothelial cells.

Polymer–Metal Composite Healthcare Materials: From Nano to Device Scale

Metals have been investigated as biomaterials for a wide range of medical applications. At nanoscale, some metals, such as gold nanoparticles, exhibit plasmonics, which have motivated researchers’ focus on biosensor development. At the device level, some metals, such as titanium, exhibit good physical properties, which could allow them to act as biomedical implants for physical support. Despite these attractive features, the non-specific delivery of metallic nanoparticles and poor tissue–device compatibility have greatly limited their performance. This review aims to illustrate the interplay between polymers and metals, and to highlight the pivotal role of polymer–metal composite/nanocomposite healthcare materials in different biomedical applications. Here, we revisit the recent plasmonic engineered platforms for biomolecules detection in cell-free samples and highlight updated nanocomposite design for (1) intracellular RNA detection, (2) photothermal therapy, and (3) nanomedicine for neurodegenerative diseases, as selected significant live cell–interactive biomedical applications. At the device scale, the rational design of polymer–metallic medical devices is of importance for dental and cardiovascular implantation to overcome the poor physical load transfer between tissues and devices, as well as implant compatibility under a dynamic fluidic environment, respectively. Finally, we conclude the treatment of these innovative polymer–metal biomedical composite designs and provide a future perspective on the aforementioned research areas.

Improve endothelialization of metallic cardiovascular stent via femtosecond laser induced micro/nanostructure dependent cells proliferation and drug delivery control

Regarding restenosis occurrence risk after metallic stent deployment in artery, stents with vascular smooth muscle cells antiproliferative agents sustained released from poly(lactic-co-glycolic acid) (PLGA) coating and endothelial cells proliferation favored surface textures were both attempted for endothelialization enhancement. In order to explore the interaction between the surface texture and performance of drug loaded PLGA coating, femtosecond laser surface treatment was used to change the surface characteristics of 316L stainless steel. Two different surface patterns in form of stripe (FSL100) and isolated island-like structure (FSL800) were firstly generated by femtosecond laser processing with 100 and 800 mW energy, then Rapamycin loaded PLGA coating was further deposited to polished and femtosecond laser processed 316L surfaces via a dip-coating method. The subsequent drug loading capacity and release profile studies confirmed the roles of surface texture. Morphological transition characteristics of the PLGA coating on the FLS100 sample indicate that the coating has integrity during degradation compared to the polished one. Finally, rapamycin eluting FLS100 stent was deployed to iliac arteries of New Zealand White rabbits with vascular plaques to demonstrate its endothelialization potential and resistance to restenosis.

Applying Principles of Regenerative Medicine to Vascular Stent Development

Stents are a widely-used device to treat a variety of cardiovascular diseases. The purpose of this review is to explore the application of regenerative medicine principles into current and future stent designs. This review will cover regeneration-relevant approaches emerging in the current research landscape of stent technology. Regenerative stent technologies include surface engineering of stents with cell secretomes, cell-capture coatings, mimics of endothelial products, surface topography, endothelial growth factors or cell-adhesive peptides, as well as design of bioresorable materials for temporary stent support. These technologies are comparatively analyzed in terms of their regenerative effects, therapeutic effects and challenges faced; their benefits and risks are weighed up for suggestions about future stent developments. This review highlights two unique regenerative features of stent technologies: selective regeneration, which is to selectively grow endothelial cells on a stent but inhibit the proliferation and migration of smooth muscle cells, and stent-assisted regeneration of ischemic tissue injury.

Sirolimus Release from Biodegradable Polymers for Coronary Stent Application: A Review

Drug-eluting stents (DESs) are commonly used for the treatment of coronary artery disease. The evolution of the drug-eluting layer on the surface of the metal stent plays an important role in DES functionality. Here, the use of biodegradable polymers has emerged as an attractive strategy because it minimizes the occurrence of late thrombosis after stent implantation. Furthermore, understanding the drug-release behavior of DESs is also important for improving the safety and efficacy of stent treatments. Drug release from biodegradable polymers has attracted extensive research attention because biodegradable polymers with different properties show different drug-release behaviors. Molecular weight, composition, glass transition temperature, crystallinity, and the degradation rate are important properties affecting the behavior of polymers. Sirolimus is a conventional anti-proliferation drug and is the most widely used drug in DESs. Sirolimus-release behavior affects endothelialization and thrombosis formation after DES implantation. In this review, we focus on sirolimus release from biodegradable polymers, including synthetic and natural polymers widely used in the medical field. We hope this review will provide valuable up-to-date information on this subject and contribute to the further development of safe and efficient DESs.

Dynamics of Endothelial Engagement and Filopodia Formation in Complex 3D Microscaffolds

The understanding of endothelium–extracellular matrix interactions during the initiation of new blood vessels is of great medical importance; however, the mechanobiological principles governing endothelial protrusive behaviours in 3D microtopographies remain imperfectly understood. In blood capillaries submitted to angiogenic factors (such as vascular endothelial growth factor, VEGF), endothelial cells can transiently transdifferentiate in filopodia-rich cells, named tip cells, from which angiogenesis processes are locally initiated. This protrusive state based on filopodia dynamics contrasts with the lamellipodia-based endothelial cell migration on 2D substrates. Using two-photon polymerization, we generated 3D microstructures triggering endothelial phenotypes evocative of tip cell behaviour. Hexagonal lattices on pillars (“open”), but not “closed” hexagonal lattices, induced engagement from the endothelial monolayer with the generation of numerous filopodia. The development of image analysis tools for filopodia tracking allowed to probe the influence of the microtopography (pore size, regular vs. elongated structures, role of the pillars) on orientations, engagement and filopodia dynamics, and to identify MLCK (myosin light-chain kinase) as a key player for filopodia-based protrusive mode. Importantly, these events occurred independently of VEGF treatment, suggesting that the observed phenotype was induced through microtopography. These microstructures are proposed as a model research tool for understanding endothelial cell behaviour in 3D fibrillary networks.

Long-Term Sustained Drug Delivery via 3D Printed Masks for the Development of a Heparin-Loaded Interlayer in Vascular Tissue Engineering Applications

Current approaches in small-diameter vascular grafts for coronary artery bypass surgeries fail to address physiological variations along the graft that contribute to thrombus formation and ultimately graft failure. We present an innovative interlayer drug delivery system that can be utilized for the sustained delivery of heparin through a graft with a high degree of temporal and spatial control. A heparin-loaded gelatin methacrylate (gelMA) interlayer sits within a biohybrid composed of decellularized bovine pericardium (dECM) and poly(propylene fumarate) (PPF), and its UV crosslinking is controlled via three-dimensional (3D) printed shadow masks. The masks can be readily designed to modulate the incident light intensity on the graft, enabling us to control the resultant gelMA crosslinking and properties. A high heparin loading efficiency was obtained in gelMA and was independent of crosslinking. We achieved sustained heparin release over the course of 2 weeks within the biohybrid material using the 3D printed mask patterns. High doses of heparin were observed to have detrimental effects on endothelial cell function. However, when exposed to heparin in a slower, more sustained manner consistent with the masks, endothelial cells behave similarly to untreated cells. Further, slower release profiles cause significantly more release of tissue factor pathway inhibitor, an anticoagulant, than a faster release profile. The heparin-loaded gelMA interlayer we have developed is a useful tool for the temporal and spatial control of heparin release that supports endothelial function and promotes an antithrombotic environment.

Exosome-eluting stents for vascular healing after ischaemic injury

Drug-eluting stents implanted after ischaemic injury reduce the proliferation of endothelial cells and vascular smooth muscle cells and thus neointimal hyperplasia. However, the eluted drug also slows down the re-endothelialization process, delays arterial healing and can increase the risk of late restenosis. Here we show that stents releasing exosomes derived from mesenchymal stem cells in the presence of reactive oxygen species enhance vascular healing in rats with renal ischaemia-reperfusion injury, promoting endothelial cell tube formation and proliferation, and impairing the migration of smooth muscle cells. Compared with drug-eluting stents and bare-metal stents, the exosome-coated stents accelerated re-endothelialization and decreased in-stent restenosis 28 days after implantation. We also show that exosome-eluting stents implanted in the abdominal aorta of rats with unilateral hindlimb ischaemia regulated macrophage polarization, reduced local vascular and systemic inflammation, and promoted muscle tissue repair.

Coatings in Decellularized Vascular Scaffolds for the Establishment of a Functional Endothelium: A Scoping Review of Vascular Graft Refinement

Developments in tissue engineering techniques have allowed for the creation of biocompatible, non-immunogenic alternative vascular grafts through the decellularization of existing tissues. With an ever-growing number of patients requiring life-saving vascular bypass grafting surgeries, the production of functional small diameter decellularized vascular scaffolds has never been more important. However, current implementations of small diameter decellularized vascular grafts face numerous clinical challenges attributed to premature graft failure as a consequence of common failure mechanisms such as acute thrombogenesis and intimal hyperplasia resulting from insufficient endothelial coverage on the graft lumen. This review summarizes some of the surface modifying coating agents currently used to improve the re-endothelialization efficiency and endothelial cell persistence in decellularized vascular scaffolds that could be applied in producing a better patency small diameter vascular graft. A comprehensive search yielding 192 publications was conducted in the PubMed, Scopus, Web of Science, and Ovid electronic databases. Careful screening and removal of unrelated publications and duplicate entries resulted in a total of 16 publications, which were discussed in this review. Selected publications demonstrate that the utilization of surface coating agents can induce endothelial cell adhesion, migration, and proliferation therefore leads to increased re-endothelialization efficiency. Unfortunately, the large variance in methodologies complicates comparison of coating effects between studies. Thus far, coating decellularized tissue gave encouraging results. These developments in re-endothelialization could be incorporated in the fabrication of functional, off-the-shelf alternative small diameter vascular scaffolds.

Surface engineering at the nanoscale: A way forward to improve coronary stent efficacy

Coronary in-stent restenosis and late stent thrombosis are the two major inadequacies of vascular stents that limit its long-term efficacy. Although restenosis has been successfully inhibited through the use of the current clinical drug-eluting stent which releases antiproliferative drugs, problems of late-stent thrombosis remain a concern due to polymer hypersensitivity and delayed re-endothelialization. Thus, the field of coronary stenting demands devices having enhanced compatibility and effectiveness to endothelial cells. Nanotechnology allows for efficient modulation of surface roughness, chemistry, feature size, and drug/biologics loading, to attain the desired biological response. Hence, surface topographical modification at the nanoscale is a plausible strategy to improve stent performance by utilizing novel design schemes that incorporate nanofeatures via the use of nanostructures, particles, or fibers, with or without the use of drugs/biologics. The main intent of this review is to deliberate on the impact of nanotechnology approaches for stent design and development and the recent advancements in this field on vascular stent performance.

Endothelial Extracellular Vesicles: From Keepers of Health to Messengers of Disease

Endothelium has a rich vesicular network that allows the exchange of macromolecules between blood and parenchymal cells. This feature of endothelial cells, along with their polarized secretory machinery, makes them the second major contributor, after platelets, to the particulate secretome in circulation. Extracellular vesicles (EVs) produced by the endothelial cells mirror the remarkable molecular heterogeneity of their parent cells. Cargo molecules carried by EVs were shown to contribute to the physiological functions of endothelium and may support the plasticity and adaptation of endothelial cells in a paracrine manner. Endothelium-derived vesicles can also contribute to the pathogenesis of cardiovascular disease or can serve as prognostic or diagnostic biomarkers. Finally, endothelium-derived EVs can be used as therapeutic tools to target endothelium for drug delivery or target stromal cells via the endothelial cells. In this review we revisit the recent evidence on the heterogeneity and plasticity of endothelial cells and their EVs. We discuss the role of endothelial EVs in the maintenance of vascular homeostasis along with their contributions to endothelial adaptation and dysfunction. Finally, we evaluate the potential of endothelial EVs as disease biomarkers and their leverage as therapeutic tools.

Combination strategies for antithrombotic biomaterials: an emerging trend towards hemocompatibility

Surface-induced thrombosis is a frequent, critical issue for blood-contacting medical devices that poses a serious threat to patient safety and device functionality. Antithrombotic material design strategies including the immobilization of anticoagulants, alterations in surface chemistries and morphology, and the release of antithrombotic compounds have made great strides in the field with the ultimate goal of circumventing the need for systemic anticoagulation, but have yet to achieve the same hemocompatibility as the native endothelium. Given that the endothelium achieves this state through the use of many mechanisms of action, there is a rising trend in combining these established design strategies for improved antithrombotic actions. Here, we describe this emerging paradigm, highlighting the apparent advantages of multiple antithrombotic mechanisms of action and discussing the demonstrated potential of this new direction.

The Combined Contribution of Vascular Endothelial Cell Migration and Adhesion to Stent Re-endothelialization

Coronary stent placement inevitably causes mechanical damage to the endothelium, leading to endothelial denudation and in-stent restenosis (ISR). Re-endothelialization depends mainly on the migration of vascular endothelial cells (VECs) adjacent to the damaged intima, as well as the mobilization and adhesion of circulating VECs. To evaluate the combined contribution of VEC migration and adhesion to re-endothelialization under flow and the influence of stent, in vitro models were constructed to simulate various endothelial denudation scales (2 mm/5 mm/10 mm) and stent deployment depths (flat/groove/bulge). Our results showed that (1) in 2 mm flat/groove/bulge models, both VEC migration and adhesion combined completed the percentage of endothelial recovery about 27, 16, and 12%, and migration accounted for about 21, 15, and 7%, respectively. It was suggested that the flat and groove models were in favor of VEC migration. (2) With the augmentation of the injury scales (5 and 10 mm), the contribution of circulating VEC adhesion on endothelial repair increased. Taken together, endothelial restoration mainly depended on the migration of adjacent VECs when the injury scale was 2 mm. The adhered cells contributed to re-endothelialization in an injury scale-dependent way. This study is helpful to provide new enlightenment for surface modification of cardiovascular implants.

Psoriatic arthritis associated with peliosis hepatis: characteristics and therapeutic management

Peliosis hepatis is characterized by hepatic sinusoidal dilatation and multiple blood-filled cystic cavities within the liver parenchyma. It can be due to infectious diseases, immunological disorders, neoplasia, and the use of various kinds of drugs. We presented the case of a nonsmoker 55-year-old man who complained about a 5-month history of arthritis. Medical history was consistent with psoriasis and hypertension. He denied any drug use or alcohol consumption. Physical examination showed extended psoriatic lesions. He had arthritis of the knees, ankles, wrists, and elbows. His body mass index was 22 kg/m². Laboratory findings revealed an increased serum gamma-glutamyl transferase level (1014 UI/L, normal value (N) 11-55) and total alkaline phosphatase (278 U/L, N 30-171). Hepatitis A, B, and C serologic test results were negative. Anti-nuclear antibodies, anti-Ro/SSA, anti-GP210, anti-SP100, anti-SLA, anti-LKM1, anti-M2, anti-LC1, and anti-PML were also negative. Histopathological examination of a liver biopsy specimen revealed peliosis hepatis.The pelvic radiograph showed bilateral ankylosis of sacroiliac joints. Hand and foot radiographs showed periosteal bone apposition. The diagnosis of psoriatic arthritis associated with peliosis hepatis was made. The patient received infliximab (5 mg/kg) with a significant improvement after 3 months of follow-up. Peliosis hepatis should be considered as a possible etiology of liver enzyme abnormalities in patients with psoriatic arthritis. We highlighted the effectiveness and safety of the TNF inhibitors in the treatment of peliosis hepatis associated with psoriatic arthritis. Key Points • Peliosis hepatis should be considered as a possible etiology of liver enzyme disturbance in patients with psoriatic arthritis. • Special caution should be advised in the management of psoriatic arthritis associated with peliosis hepatis to avoid the worsening of liver function. • Infliximab is suggested as a possible treatment of peliosis hepatis associated with psoriatic arthritis.

Biocompatible and functional inorganic magnesium ceramic particles for biomedical applications

Magnesium ceramics hold promise for numerous biological applications. This review covers the synthesis of magnesium ceramic particles with specific morphologies and potential modification techniques. Magnesium ceramic particles possess multiple characteristics directly applicable to human biology; they are anti-inflammatory, antibacterial, antiviral, and offer anti-cancer effects. Based on these advantages, magnesium hydroxide nanoparticles have been extensively utilized across biomedical fields. In a vascular stent, the incorporation of magnesium ceramic nanoparticles enhances re-endothelialization. Additionally, tissue regeneration for bone, cartilage, and kidney can be promoted by magnesium ceramics. This review enables researchers to identify the optimum synthetic conditions to prepare magnesium ceramics with specific morphologies and sizes and select the appropriate modification protocols. It is also intended to elucidate the desirable physicochemical properties and biological benefits of magnesium ceramics.

S-Nitrosoglutathione-Based Nitric Oxide-Releasing Nanofibers Exhibit Dual Antimicrobial and Antithrombotic Activity for Biomedical Applications

The novel use of nanofibers as a physical barrier between blood and medical devices has allowed for modifiable, innovative surface coatings on devices ordinarily plagued by thrombosis, delayed healing, and chronic infection. In this study, the nitric oxide (NO) donor S-nitrosoglutathione (GSNO) is blended with the biodegradable polymers polyhydroxybutyrate (PHB) and polylactic acid (PLA) for the fabrication of hemocompatible, antibacterial nanofibers tailored for blood-contacting applications. Stress/strain behavior of different concentrations of PHB and PLA is recorded to optimize the mechanical properties of the nanofibers. Nanofibers incorporated with different concentrations of GSNO (10, 15, 20 wt%) are evaluated based on their NO-releasing kinetics. PLA/PHB + 20 wt% GSNO nanofibers display the greatest NO release over 72 h (0.4-1.5 × 10-10  mol mg-1 min-1 ). NO-releasing fibers successfully reduce viable adhered bacterial counts by ≈80% after 24 h of exposure to Staphylococcus aureus. NO-releasing nanofibers exposed to porcine plasma reduce platelet adhesion by 64.6% compared to control nanofibers. The nanofibers are found noncytotoxic (>95% viability) toward NIH/3T3 mouse fibroblasts, and 4',6-diamidino-2-phenylindole and phalloidin staining shows that fibroblasts cultured on NO-releasing fibers have improved cellular adhesion and functionality. Therefore, these novel NO-releasing nanofibers provide a safe antimicrobial and hemocompatible coating for blood-contacting medical devices.

Merging 3D printing with electrospun biodegradable small-caliber vascular grafts immobilized with VEGF

The major challenge of commercially available vascular substitutes comes from their limitations in terms of hydrophobic surface, which is hostile to cell growth. To date, tissue-engineered and synthetic grafts have not translated well to clinical trials when looking at small diameters. We conceptualized a cell-free structurally reinforced biodegradable vascular graft recapitulating the anisotropic feature of a native blood vessel. The nanofibrous scaffold is designed in such a way that it will gradually degrade systematically to yield a neo-vessel, facilitated by an immobilized bioactive molecule-vascular endothelial growth factor (VEGF). The nano-topographic cue of the device is capable of direct host cell infiltration. We evaluated the burst pressure, histology, hemocompatibility, compression test, and mechanical analysis of the new graft. The graft implanted into the carotid artery of a porcine model demonstrated a good patency rate as early as two week post-implantation. This graft reinforced design approach when employed in vascular tissue engineering might strongly influencing regenerative medicine.

A Novel Hybrid Membrane VAD as First Step Toward Hemocompatible Blood Propulsion

Heart failure is a raising cause of mortality. Heart transplantation and ventricular assist device (VAD) support represent the only available lifelines for end stage disease. In the context of donor organ shortage, the future role of VAD as destination therapy is emerging. Yet, major drawbacks are connected to the long-term implantation of current devices. Poor VAD hemocompatibility exposes the patient to life-threatening events, including haemorrhagic syndromes and thrombosis. Here, we introduce a new concept of artificial support, the Hybrid Membrane VAD, as a first-of-its-kind pump prototype enabling physiological blood propulsion through the cyclic actuation of a hyperelastic membrane, enabling the protection from the thrombogenic interaction between blood and the implant materials. The centre of the luminal membrane surface displays a rationally-developed surface topography interfering with flow to support a living endothelium. The precast cell layer survives to a range of dynamically changing pump actuating conditions i.e., actuation frequency from 1 to 4 Hz, stroke volume from 12 to 30 mL, and support duration up to 313 min, which are tested both in vitro and in vivo, ensuring the full retention of tissue integrity and connectivity under challenging conditions. In summary, the presented results constitute a proof of principle for the Hybrid Membrane VAD concept and represent the basis for its future development towards clinical validation.

Successful Reduction of Neointimal Hyperplasia on Stainless Steel Coronary Stents by Titania Nanotexturing

Bare metal stents (BMSs) of stainless steel (SS) were surface engineered to develop nanoscale titania topography using a combination of physical vapor deposition and thermochemical processing. The nanoleafy architecture formed on the stent surface remained stable and adherent upon repeated crimping and expansion, as well as under flow. This titania nanoengineered stent showed a preferential proliferation of endothelial cells over smooth muscle cells in vitro, which is an essential requirement for improving the in vivo endothelialization, with concurrent reduction of intimal hyperplasia. The efficacy of this surface-modified stent was assessed after implantation in rabbit iliac arteries for 8 weeks. Significant reduction in neointimal thickening and thereby in-stent restenosis with complete endothelial coverage was observed for the nanotextured stents, compared to BMSs, even without the use of any antiproliferative agents or polymers as in drug-eluting stents. Nanotexturing of stents did not induce any inflammatory response, akin to BMSs. This study thus indicates the effectiveness of a facile titania nanotopography on SS stents for coronary applications and the possibility of bringing this low-priced material back to clinics.

Development of in vitro endothelialized drug-eluting stent using human peripheral blood-derived endothelial progenitor cells

We propose in vitro endothelialization of drug-eluting stents (DES) to overcome late stent thrombosis by directly introducing late-outgrowth human endothelial progenitor cells (EPCs) at the target site utilizing abluminal DES. Isolated EPCs were confirmed as late-outgrowth EPCs by flow cytometric analysis. Abluminally paclitaxel-loaded stents were seeded with different cell concentrations and durations to determine optimal seeding conditions, in both uncrimped and crimped configurations. The seeding yield was determined by evaluating the percent coverage of the stent struts' area. The EPC-seeded DES were exposed to arterial shear stress to evaluate the effect of high shear stress on EPCs. To investigate how much paclitaxel elutes during the seeding procedure, a pharmacokinetic analysis was performed. Finally, to validate the proof of concept, EPC-seeded DES were placed on a fibrin matrix with and without smooth muscle cells (SMCs) and cultured for 3 days under perfusion. The seeding procedure resulted in 47% and 26% coverage of the stent surface in uncrimped and crimped conditions, respectively. After the optimal seeding, almost 99% of drug was still available. When EPC-seeded DES were placed on a fibrin matrix and cultured for 3 days, the EPCs confluently covered the stent surface and spread to the surrounding fibrin gel. When EPC-seeded DES were placed on SMC-containing fibrin layers, cells in contact with the struts died. EPCs can be successfully seeded onto DES without losing drug-eluting capability, and EPCs exhibit sufficient proliferative ability. EPC-seeded DES may combine early re-endothelialization ability with the antirestenotic effectiveness of DES.

Overview of the latest developments in the field of drug-eluting stent technology

Angioplasty with stent implantation is considered to be the basic treatment method of stenosis of blood vessels. The process of stent implantation changed through the years, from stents made only from metals, produced from polymers, to biodegradable ones and those which elute drugs. The purpose of this review is to outline the development of this medical procedure and present the advantages and disadvantages of each type of stent.

Crystallized TiO2 Nanosurfaces in Biomedical Applications

Crystallization alters the characteristics of TiO2 nanosurfaces, which consequently influences their bio-performance. In various biomedical applications, the anatase or rutile crystal phase is preferred over amorphous TiO2. The most common crystallization technique is annealing in a conventional furnace. Methods such as hydrothermal or room temperature crystallization, as well as plasma electrolytic oxidation (PEO) and other plasma-induced crystallization techniques, present more feasible and rapid alternatives for crystal phase initiation or transition between anatase and rutile phases. With oxygen plasma treatment, it is possible to achieve an anatase or rutile crystal phase in a few seconds, depending on the plasma conditions. This review article aims to address different crystallization techniques on nanostructured TiO2 surfaces and the influence of crystal phase on biological response. The emphasis is given to electrochemically anodized nanotube arrays and their interaction with the biological environment. A short overview of the most commonly employed medical devices made of titanium and its alloys is presented and discussed.

Characterization of carotid endothelial cell proliferation on Au, Au/GO, and Au/rGO surfaces by electrical impedance spectroscopy

To the best of the authors' knowledge, testing the biocompatibility of graphene coatings can be considered as the first to demonstrate human carotid endothelial cell (HCtAEC) proliferation on Au, graphene oxide-coated Au (Au/GO), and reduced graphene oxide-coated Au (Au/rGO) surfaces. We hypothesized that stent material modified with graphene (G)-based coatings could be used as electrodes for electrical impedance spectroscopy (EIS) in monitoring cell cultures, i.e., endothelialization. Alamar Blue cell viability assay and cell staining and cell counting with optical images were performed. For EIS analysis, an EIS sensor consisting of Au surface electrodes was produced by the photolithographic technique. Surface characterizations were performed by considering scanning electron microscope (SEM) and water contact angle analyses. Results showed that GO and rGO coatings did not prevent neither the electrical measurements nor the cell proliferation and that rGO had a positive effect on HCtAEC proliferation. The rate of increase of impedance change from day 1 to day 10 was nearly fivefold for all electrode surfaces. Alamar Blue assay performed to monitor cell proliferation rates between groups, and rGO has shown the highest Alamar Blue reduction value of 43.65 ± 8.79%. Graphical abstract.

Vascular reconstruction: A major challenge in developing a functional whole solid organ graft from decellularized organs

Bioengineering a functional organ holds great potential to overcome the current gap between the organ need and shortage of available organs. Whole organ decellularization allows the removal of cells from large-scale organs, leaving behind extracellular matrices containing different growth factors, structural proteins, and a vascular network with a bare surface. Successful application of decellularized tissues as transplantable organs is hampered by the inability to completely reline the vasculature by endothelial cells (ECs), leading to blood coagulation, loss of vascular patency, and subsequent death of reseeded cells. Therefore, an intact, continuous layer of endothelium is essential to maintain proper functioning of the vascular system, which includes the transfer of nutrients to surrounding tissues and protecting other types of cells from shear stress. Here, we aimed to summarize the available cell sources that can be used for reendothelialization in addition to different trials performed by researchers to reconstruct vascularization of decellularized solid organs. Additionally, different techniques for enhancing reendothelialization and the methods used for evaluating reendothelialization efficiency along with the future prospective applications of this field are discussed. STATEMENT OF SIGNIFICANCE: Despite the great progress in whole organ decellularization, reconstruction of vasculature within the engineered constructs is still a major roadblock. Reconstructed endothelium acts as a multifunctional barrier of vessels, which can reduce thrombosis and help delivering of oxygen and nutrients throughout the whole organ. Successful reendothelialization can be achieved through reseeding of appropriate cell types on the naked vasculature with or without modification of its surface. Here, we present the current research milestones that so far established to reconstruct the vascular network in addition to the methods used for evaluating the efficiency of reendotheilization. Thus, this review is quite significant and will aid the researchers to know where we stand toward biofabricating a transplantable organ from decellularizd extracellular matrix.

Biomechanical studies on biomaterial degradation and co-cultured cells: mechanisms, potential applications, challenges and prospects

Biomechanics contains a wide variety of research fields related to biology and mechanics. Actually, to better study or develop a tissue-engineered system, it is now widely recognized that there is no complete nor meaningful study without considering biomechanical factors and the cell response or adaptation to biomechanics. In that respect, this review will focus on not only the influence of biomechanics in biomaterial degradation and co-cultured cells, based on current major frontier research findings, but also the challenges and prospects in biomechanical research. Particularly, through the elaboration of certain typical forces affecting biomaterial degradation and celluar functions, this paper tries to reveal the possible mechanisms, and thus provide ideas on how to design or optimize co-culture systems and apply external forces for proper cell and tissue engineering. Furthermore, while emphasizing the importance of the mechanical control of the cell phenotype and fate, it is expected that these achievements can pave the way to materials-based therapies for different pathological conditions, including diagnosis and treatment of cancer.

Augmented re-endothelialization and anti-inflammation of coronary drug-eluting stent by abluminal coating with magnesium hydroxide

Drug-eluting stents (DESs) have been widely used as a treatment approach for coronary artery diseases. Generally, conventional DESs were fully covered with drugs and biodegradable polymers on both abluminal and luminal layers (i.e., conformal coating). However, uncontrolled drug release from the luminal drug-coating layer of the stent is known to inhibit re-endothelialization. Furthermore, the acidification of the surrounding tissue by the decomposed coating polymer causes inflammation, resulting in restenosis and late thrombosis. To overcome these limitations, here we demonstrated a functional DES coated with poly(lactic-co-glycolic acid) (PLGA), sirolimus (SRL), and magnesium hydroxide (Mg(OH)2, MH) precisely only on the abluminal layer. The acidic neutralization effect of MH was elucidated by measuring the pH change of the fabricated film in PBS solution. In an in vitro cell study, the stent coated with MH exhibited higher compatibility with human coronary artery endothelial cells (ECs) and a lower inflammation score as compared to the control stent. Finally, in an in vivo large porcine model, the abluminal coated DES with SRL and MH showed excellent re-endothelialization and anti-inflammatory and anti-thrombotic effects. In conclusion, it is believed that this approach has great potential for the development of functional DES for the treatment of cardiovascular diseases.

Endothelialization of cardiovascular devices

Blood-contacting surfaces of cardiovascular devices are not biocompatible for creating an endothelial layer on them. Numerous research studies have mainly sought to modify these surfaces through physical, chemical and biological means to ease early endothelial cell (EC) adhesion, migration and proliferation, and eventually to build an endothelial layer on the surfaces. The first priority for surface modification is inhibition of protein adsorption that leads to inhibition of platelet adhesion to the device surfaces, which may favor EC adhesion. Surface modification through surface texturing, if applicable, can bring some hopeful outcomes in this regard. Surface modifications through chemical and/or biological means may play a significant role in easy endothelialization of cardiovascular devices and inhibit smooth muscle cell proliferation. Cellular engineering of cells relevant to endothelialization can boost the positive outcomes obtained through surface engineering. This review briefly summarizes recent developments and research in early endothelialization of cardiovascular devices. STATEMENT OF SIGNIFICANCE: Endothelialization of cardiovascular implants, including heart valves, vascular stents and vascular grafts is crucial to solve many problems in our health care system. Numerous research efforts have been made to improve endothelialization on the surfaces of cardiovascular implants, mainly through surface modifications in three ways - physically, chemically and biologically. This review is intended to highlight comprehensive research studies to date on surface modifications aiming for early endothelialization on the blood-contacting surfaces of cardiovascular implants. It also discusses future perspectives to help guide endothelialization strategies and inspire further innovations.

Id-1 Promotes Reendothelialization In The Early Phase After Vascular Injury Through Activation Of NFkB/survivin Signaling Pathway

BACKGROUND

Percutaneous coronary intervention (PCI) treatment can benefit patients, but also cause irreversible mechanical damage to the vascular endothelium, ultimately leading to restenosis of the target vessel. Thus, achieving rapid re-endothelialization and restoring the integrity of the vascular endothelium and function plays an important role in inhibiting neointimal hyperplasia and preventing restenosis. Id1 (inhibitor of DNA binding/differentiation factor 1) plays an important role in promoting cell proliferation and angiogenesis.

STUDY OBJECTIVE

This study aims to investigate the relationship between Id1 and NFκB/survivin signaling pathways and their role in injured vascular repair by establishing a rat carotid balloon injury model.

METHODS

The carotid artery model of rat balloon injury was established. The injured common carotid artery was obtained at different time points after vascular injury. RNA and protein were extracted and the mRNA and protein expression levels of Id1, NFκB and survivin were detected in vascular injury. The NFκB blocker BAY 11-7082 and survivin blocker YM155 were used and the effects of Id1, NFκB, survivin mRNA and protein expression, revascularization of blood vessels and neointimal responsiveness after vascular injury were observed in the vascular tissues of Ad-Id1 transfected balloon injury.

RESULTS

Id1, NFκB and survivin were expressed in injured rat carotid arteries. Overexpression of Id1 promoted re-endothelialization of injured vessels through NFκB/survivin signaling pathway, inhibited early vascular endometrial reactive hyperplasia; blocked NFκB the/survivin signaling pathway attenuates the re-endothelialization of Ad-Id1 and the early endothelium of Ad-Id1. Blocking the NFκB/survivin signaling pathway attenuates the re-endothelialization and early reactive hyperplasia of vascular intima of Ad-Id1.

CONCLUSION

NF-kappa B/survivin signaling pathway may play an important role in Id1 promoting vascular re-endothelialization, inhibiting neointimal hyperplasia and preventing vascular restenosis.

Transcription Factors Targeted by miRNAs Regulating Smooth Muscle Cell Growth and Intimal Thickening after Vascular Injury

Neointima formation after percutaneous coronary intervention (PCI) is a manifestation of “phenotype switching” by vascular smooth muscle cells (SMC), a process that involves de-differentiation from a contractile quiescent phenotype to one that is richly synthetic. In response to injury, SMCs migrate, proliferate, down-regulate SMC-specific differentiation genes, and later, can revert to the contractile phenotype. The vascular response to injury is regulated by microRNAs (or miRNAs), small non-coding RNAs that control gene expression. Interactions between miRNAs and transcription factors impact gene regulatory networks. This article briefly reviews the roles of a range of miRNAs in molecular and cellular processes that control intimal thickening, focusing mainly on transcription factors, some of which are encoded by immediate-early genes. Examples include Egr-1, junB, KLF4, KLF5, Elk-1, Ets-1, HMGB1, Smad1, Smad3, FoxO4, SRF, Rb, Sp1 and c-Myb. Such mechanistic information could inform the development of strategies that block SMC growth, neointima formation, and potentially overcome limitations of lasting efficacy following PCI.