Anisotropic conductive reduced graphene oxide/silk matrices promote post-infarction myocardial function by restoring electrical integrity

Alginate hydrogel-encapsulated bone marrow-derived mesenchymal stem cells and crocin improve cardiac function in a rat model of myocardial infarction

Cardiovascular diseases (CVDs), particularly myocardial infarction (MI), are the leading cause of mortality worldwide and significantly contribute to morbidity. This study incorporated varying concentrations of crocin (CRO) into alginate hydrogel (ALG) to enhance cardiac function. Following synthesizing the hydrogel, it was characterized through a series of experiments, including morphological assessment, rheological analysis, cytocompatibility testing, and cellular viability evaluation. The therapeutic efficacy of the synthesized hydrogel in combination with bone-derived mesenchymal stem cells (BMSCs), was then investigated in a rat model of MI using echocardiography, histology, and immunohistochemistry. The results indicated that the prepared hydrogels exhibited adequate porosity and favorable rheological properties. Notably, CRO at lower concentrations significantly improved the viability of BMSCs. To evaluate the therapeutic potential in vivo, the ALG/CRO hydrogel loaded with BMSCs was implanted into the MI region of the rat model. The findings demonstrate that the ALG/CRO hydrogel can significantly reduce scar thickness and promote angiogenesis, thereby improving the recovery of cardiac function. Consequently, the ALG/CRO hydrogel has the potential to serve as an injectable carrier for the delivery of cells aimed at cardiac regeneration.

Nanomaterials: Promising Tools for the Diagnosis and Treatment of Myocardial Infarction

Myocardial infarction (MI) is the leading cause of mortality from cardiovascular diseases. Rapid diagnosis and effective treatment are critical for improving patient prognosis. Although current diagnostic and therapeutic approaches have made significant progress, they still face challenges such as ischemia-reperfusion injury, microcirculatory disorders, adverse cardiac remodeling, and inflammatory responses. These issues highlight the urgent need for innovative solutions. Nanomaterials, with their diverse types, excellent physicochemical properties, biocompatibility, and targeting capabilities, offer promising potential in addressing these challenges. Advances in nanotechnology have increasingly drawn attention to the application of nanomaterials in both diagnosing and treating myocardial infarction. We summarize the pathophysiological mechanisms and staging of myocardial infarction. We systematically review the applications of nanomaterials in MI diagnosis, including the detection of biomarkers and imaging techniques, as well as in MI treatment, encompassing anti-inflammatory effects, antioxidant stress, inhibition of fibrosis, promotion of angiogenesis, and cardiac conduction repair. We analyze the existing challenges and provide insights into future research directions and potential solutions. Specifically, we discuss the need for rigorous safety assessments, long-term efficacy studies, and the development of robust strategies for translating laboratory findings into clinical practice. In conclusion, nanotechnology holds significant promise as a new strategy for diagnosing and treating myocardial infarction. Its potential to enhance clinical outcomes and revolutionize patient care makes it an exciting area of research with practical applications in real-world clinical settings.

Anisotropic conductive scaffolds for post-infarction cardiac repair

Myocardial infarction (MI) remains one of the most common and lethal cardiovascular diseases (CVDs), leading to the deterioration of cardiac function due to myocardial cell necrosis and fibrous scar tissue formation. Myocardial infarction (MI) remains one of the most common and lethal cardiovascular diseases (CVDs), leading to the deterioration of cardiac function due to myocardial cell necrosis and fibrous scar tissue formation. After MI, the anisotropic structural properties of myocardial tissue are destroyed, and its mechanical and electrical microenvironment also undergoes a series of pathological changes, such as ventricular wall stiffness, abnormal contraction, conduction network disruption, and irregular electrical signal propagation, which may further induce myocardial remodeling and even lead to heart failure. Therefore, bionic reconstruction of the anisotropic structural-mechanical-electrical microenvironment of the infarct area is key to repairing damaged myocardium. This article first summarizes the pathological changes in muscle fibre structure and conductive microenvironment after cardiac injury, and focuses on the classification and preparation methods of anisotropic conductive materials. In addition, the effects of these anisotropic conductive materials on the behavior of cardiac resident cells after myocardial infarction, such as directional growth, maturation, proliferation and migration, and the differentiation fate of stem cells and the possible molecular mechanisms involved are summarized. The design strategies for anisotropic conductive scaffolds for myocardial repair in future clinical research are also discussed, with the aim of providing new insights for researchers in related fields.

A Heart Rate Matched Patch for Mechano-Chemical Treatment of Myocardial Infarction: Optimal Design and Transspecies Application

After myocardial infarction (MI), ventricular dilation and the microscopic passive stretching of the infarcted border zone is the meaning contributor to the continuous expansion of myocardial fibrosis. Epicardial hydrogel patches have been demonstrated to alleviate this sequela of MI in small-animal models. However, these have not been successfully translated to humans or even large animals, in part because of challenges in attaining both the greater stiffness and slower viscoelastic relaxation that mathematical models predict to be optimal for application to larger, slower-beating hearts. Here, using borate-based dynamic covalent chemistry, we develop an injectable "heart rate matched" viscoelastic gelatin (VGtn) hydrogel with a gel point tunable across the stiffnesses and frequencies that are predicted to transspecies and cross-scale cardiac repair after MI. Small-animal experiments demonstrated that, compared to heart rate mismatched patches, the heart rate matched VGtn patches inhibited ventricular bulging and attenuated stress concentrations in the myocardium after MI. In particular, the viscoelastic patch can coordinate the microscopic strain at the infarction boundary. VGtn loaded with anti-fibrotic agents further reduced myocardial damage and promoted angiogenesis in the myocardium. The tuned heart rate matched patches demonstrated similar benefits in a larger-scale and lower heart rate porcine MI model. Results suggest that heart rate matched VGtn patches may hold potential for clinical translation.

Electrically conductive coatings in tissue engineering

Recent interest in tissue engineering (TE) has focused on electrically conductive biomaterials. This has been inspired by the characteristics of the cells' microenvironment where signalling is supported by electrical stimulation. Numerous studies have demonstrated the positive influence of electrical stimulation on cell excitation to proliferate, differentiate, and deposit extracellular matrix. Even without external electrical stimulation, research shows that electrically active scaffolds can improve tissue regeneration capacity. Tissues like bone, muscle, and neural contain electrically excitable cells that respond to electrical cues provided by implanted biomaterials. To introduce an electrical pathway, TE scaffolds can incorporate conductive polymers, metallic nanoparticles, and ceramic nanostructures. However, these materials often do not meet implantation criteria, such as maintaining mechanical durability and degradation characteristics, making them unsuitable as scaffold matrices. Instead, depositing conductive layers on TE scaffolds has shown promise as an efficient alternative to creating electrically conductive structures. A stratified scaffold with an electroactive surface synergistically excites the cells through active top-pathway, with/without electrical stimulation, providing an ideal matrix for cell growth, proliferation, and tissue deposition. Additionally, these conductive coatings can be enriched with bioactive or pharmaceutical components to enhance the scaffold's biomedical performance. This review covers recent developments in electrically active biomedical coatings for TE. The physicochemical and biological properties of conductive coating materials, including polymers (polypyrrole, polyaniline and PEDOT:PSS), metallic nanoparticles (gold, silver) and inorganic (ceramic) particles (carbon nanotubes, graphene-based materials and Mxenes) are examined. Each section explores the conductive coatings' deposition techniques, deposition parameters, conductivity ranges, deposit morphology, cell responses, and toxicity levels in detail. Furthermore, the applications of these conductive layers, primarily in bone, muscle, and neural TE are considered, and findings from in vitro and in vivo investigations are presented. STATEMENT OF SIGNIFICANCE: Tissue engineering (TE) scaffolds are crucial for human tissue replacement and acceleration of healing. Neural, muscle, bone, and skin tissues have electrically excitable cells, and their regeneration can be enhanced by electrically conductive scaffolds. However, standalone conductive materials often fall short for TE applications. An effective approach involves coating scaffolds with a conductive layer, finely tuning surface properties while leveraging the scaffold's innate biological and physical support. Further enhancement is achieved by modifying the conductive layer with pharmaceutical components. This review explores the under-reviewed topic of conductive coatings in tissue engineering, introducing conductive biomaterial coatings and analyzing their biological interactions. It provides insights into enhancing scaffold functionality for tissue regeneration, bridging a critical gap in current literature.

Application of Pro-angiogenic Biomaterials in Myocardial Infarction

Biomaterials have potential applications in the treatment of myocardial infarction (MI). These biomaterials have the ability to mechanically support the ventricular wall and to modulate the inflammatory, metabolic, and local electrophysiological microenvironment. In addition, they can play an equally important role in promoting angiogenesis, which is the primary prerequisite for the treatment of MI. A variety of biomaterials are known to exert pro-angiogenic effects, but the pro-angiogenic mechanisms and functions of different biomaterials are complex and diverse, and have not yet been systematically described. This review will focus on the pro-angiogenesis of biomaterials and systematically describe the mechanisms and functions of different biomaterials in promoting angiogenesis in MI.

Insights into the prospects of nanobiomaterials in the treatment of cardiac arrhythmia

Cardiac arrhythmia, a disorder of abnormal electrical activity of the heart that disturbs the rhythm of the heart, thereby affecting its normal function, is one of the leading causes of death from heart disease worldwide and causes millions of deaths each year. Currently, treatments for arrhythmia include drug therapy, radiofrequency ablation, cardiovascular implantable electronic devices (CIEDs), including pacemakers, defibrillators, and cardiac resynchronization therapy (CRT). However, these traditional treatments have several limitations, such as the side effects of medication, the risks of device implantation, and the complications of invasive surgery. Nanotechnology and nanomaterials provide safer, effective and crucial treatments to improve the quality of life of patients with cardiac arrhythmia. The large specific surface area, controlled physical and chemical properties, and good biocompatibility of nanobiomaterials make them promising for a wide range of applications, such as cardiovascular drug delivery, tissue engineering, and the diagnosis and therapeutic treatment of diseases. However, issues related to the genotoxicity, cytotoxicity and immunogenicity of nanomaterials remain and require careful consideration. In this review, we first provide a brief overview of cardiac electrophysiology, arrhythmia and current treatments for arrhythmia and discuss the potential applications of nanobiomaterials before focusing on the promising applications of nanobiomaterials in drug delivery and cardiac tissue repair. An in-depth study of the application of nanobiomaterials is expected to provide safer and more effective therapeutic options for patients with cardiac arrhythmia, thereby improving their quality of life.

Cardiac tissue engineering: an emerging approach to the treatment of heart failure

Heart failure is a major health problem in which the heart is unable to pump enough blood to meet the body's needs. It is a progressive disease that becomes more severe over time and can be caused by a variety of factors, including heart attack, cardiomyopathy and heart valve disease. There are various methods to cure this disease, which has many complications and risks. The advancement of knowledge and technology has proposed new methods for many diseases. One of the promising new treatments for heart failure is tissue engineering. Tissue engineering is a field of research that aims to create living tissues and organs to replace damaged or diseased tissue. The goal of tissue engineering in heart failure is to improve cardiac function and reduce the need for heart transplantation. This can be done using the three important principles of cells, biomaterials and signals to improve function or replace heart tissue. The techniques for using cells and biomaterials such as electrospinning, hydrogel synthesis, decellularization, etc. are diverse. Treating heart failure through tissue engineering is still under development and research, but it is hoped that there will be no transplants or invasive surgeries in the near future. In this study, based on the most important research in recent years, we will examine the power of tissue engineering in the treatment of heart failure.

Emergence of graphene as a novel nanomaterial for cardiovascular applications

Cardiovascular diseases (CDs) are the foremost cause of death worldwide. Several promising therapeutic methods have been developed for this approach, including pharmacological, surgical intervention, cell therapy, or biomaterial implantation since heart tissue is incapable of regenerating and healing on its own. The best treatment for heart failure to date is heart transplantation and invasive surgical intervention, despite their invasiveness, donor limitations, and the possibility of being rejected by the patient's immune system. To address these challenges, research is being conducted on less invasive and efficient methods. Consequently, graphene-based materials (GBMs) have attracted a great deal of interest in the last decade because of their exceptional mechanical, electrical, chemical, antibacterial, and biocompatibility properties. An overview of GBMs' applications in the cardiovascular system has been presented in this article. Following a brief explanation of graphene and its derivatives' properties, the potential of GBMs to improve and restore cardiovascular system function by using them as cardiac tissue engineering, stents, vascular bypass grafts,and heart valve has been discussed.

Reduced Graphene-Oxide-Doped Elastic Biodegradable Polyurethane Fibers for Cardiomyocyte Maturation

Conductive biomaterials offer promising solutions to enhance the maturity of cultured cardiomyocytes. While the conventional culture of cardiomyocytes on nonconductive materials leads to more immature characteristics, conductive microenvironments have the potential to support sarcomere development, gap junction formation, and beating of cardiomyocytes in vitro. In this study, we systematically investigated the behaviors of cardiomyocytes on aligned electrospun fibrous membranes composed of elastic and biodegradable polyurethane (PU) doped with varying concentrations of reduced graphene oxide (rGO). Compared to PU and PU-4%rGO membranes, the PU-10%rGO membrane exhibited the highest conductivity, approaching levels close to those of native heart tissue. The PU-rGO membranes retained anisotropic viscoelastic behavior similar to that of the porcine left ventricle and a superior tensile strength. Neonatal rat cardiomyocytes (NRCMs) and human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) on the PU-rGO membranes displayed enhanced maturation with cell alignment and enhanced sarcomere structure and gap junction formation with PU-10%rGO having the most improved sarcomere structure and CX-43 presence. hiPSC-CMs on the PU-rGO membranes exhibited a uniform and synchronous beating pattern compared with that on PU membranes. Overall, PU-10%rGO exhibited the best performance for cardiomyocyte maturation. The conductive PU-rGO membranes provide a promising matrix for in vitro cardiomyocyte culture with promoted cell maturation/functionality and the potential for cardiac disease treatment.

Applications of Graphene Family Nanomaterials in Regenerative Medicine: Recent Advances, Challenges, and Future Perspectives

Graphene family nanomaterials (GFNs) have attracted considerable attention in diverse fields from engineering and electronics to biomedical applications because of their distinctive physicochemical properties such as large specific surface area, high mechanical strength, and favorable hydrophilic nature. Moreover, GFNs have demonstrated the ability to create an anti-inflammatory environment and exhibit antibacterial effects. Consequently, these materials hold immense potential in facilitating cell adhesion, proliferation, and differentiation, further promoting the repair and regeneration of various tissues, including bone, nerve, oral, myocardial, and vascular tissues. Note that challenges still persist in current applications, including concerns regarding biosecurity risks, inadequate adhesion performance, and unsuitable degradability as matrix materials. This review provides a comprehensive overview of current advancements in the utilization of GFNs in regenerative medicine, as well as their molecular mechanism and signaling targets in facilitating tissue repair and regeneration. Future research prospects for GFNs, such as potential in promoting ocular tissue regeneration, are also discussed in details. We hope to offer a valuable reference for the clinical application of GFNs in the treatment of bone defects, nerve damage, periodontitis, and atherosclerosis.

A cigarette filter-derived biomimetic cardiac niche for myocardial infarction repair

Cell implantation offers an appealing avenue for heart repair after myocardial infarction (MI). Nevertheless, the implanted cells are subjected to the aberrant myocardial niche, which inhibits cell survival and maturation, posing significant challenges to the ultimate therapeutic outcome. The functional cardiac patches (CPs) have been proved to construct an elastic conductive, antioxidative, and angiogenic microenvironment for rectifying the aberrant microenvironment of the infarcted myocardium. More importantly, inducing implanted cardiomyocytes (CMs) adapted to the anisotropic arrangement of myocardial tissue by bioengineered structural cues within CPs are more conducive to MI repair. Herein, a functional Cig/(TA-Cu) CP served as biomimetic cardiac niche was fabricated based on structural anisotropic cigarette filter by modifying with tannic acid (TA)-chelated Cu2+ (TA-Cu complex) via a green method. This CP possessed microstructural anisotropy, electrical conductivity and mechanical properties similar to natural myocardium, which could promote elongation, orientation, maturation, and functionalization of CMs. Besides, the Cig/(TA-Cu) CP could efficiently scavenge reactive oxygen species, reduce CM apoptosis, ultimately facilitating myocardial electrical integration, promoting vascular regeneration and improving cardiac function. Together, our study introduces a functional CP that integrates multimodal cues to create a biomimetic cardiac niche and provides an effective strategy for cardiac repair.

Impact of the Reduction Time-Dependent Electrical Conductivity of Graphene Nanoplatelet-Coated Aligned Bombyx mori Silk Scaffolds on Electrically Stimulated Axonal Growth

Graphene-based nanomaterials, renowned for their outstanding electrical conductivity, have been extensively studied as electroconductive biomaterials (ECBs) for electrically stimulated tissue regeneration. However, using eco-friendly reducing agents like l-ascorbic acid (l-Aa) can result in lower conductive properties in these ECBs, limiting their full potential for smooth charge transfer in living tissues. Moreover, creating a flexible biomaterial scaffold using these materials that accurately mimics a specific tissue microarchitecture, such as nerves, poses additional challenges. To address these issues, this study developed a microfibrous scaffold of Bombyx mori (Bm) silk fibroin uniformly coated with graphene nanoplatelets (GNPs) through a vacuum coating method. The scaffold's electrical conductivity was optimized by varying the reduction period using l-Aa. The research systematically investigated how different reduction periods impact scaffold properties, focusing on electrical conductivity and its significance on electrically stimulated axonal growth in PC12 cells. Results showed that a 48 h reduction significantly increased surface electrical conductivity by 100-1000 times compared to a shorter or no reduction process. l-Aa contributed to stabilizing the reduced GNPs, demonstrated by a slow degradation profile and sustained conductivity even after 60 days in a proteolytic environment. β (III) tubulin immunostaining of PC12 cells on varied silk:GNP scaffolds under pulsed electrical stimulation (ES, 50 Hz frequency, 1 ms pulse width, and amplitudes of 100 and 300 mV/cm) demonstrates accelerated axonal growth on scaffolds exhibiting higher conductivity. This is supported by upregulated intracellular Ca2+ dynamics immediately after ES on the scaffolds with higher conductivity, subjected to a prolonged reduction period. The study showcases a sustainable reduction approach using l-Aa in combination with natural Bm silk fibroin to create a highly conductive, mechanically robust, and stable silk:GNP-based aligned fibrous scaffold. These scaffolds hold promise for functional regeneration in electrically excitable tissues such as nerves, cardiac tissue, and muscles.

Resorbable conductive materials for optimally interfacing medical devices with the living

Implantable and wearable bioelectronic systems are arising growing interest in the medical field. Linking the microelectronic (electronic conductivity) and biological (ionic conductivity) worlds, the biocompatible conductive materials at the electrode/tissue interface are key components in these systems. We herein focus more particularly on resorbable bioelectronic systems, which can safely degrade in the biological environment once they have completed their purpose, namely, stimulating or sensing biological activity in the tissues. Resorbable conductive materials are also explored in the fields of tissue engineering and 3D cell culture. After a short description of polymer-based substrates and scaffolds, and resorbable electrical conductors, we review how they can be combined to design resorbable conductive materials. Although these materials are still emerging, various medical and biomedical applications are already taking shape that can profoundly modify post-operative and wound healing follow-up. Future challenges and perspectives in the field are proposed.

Silk fibroin-derived electrospun materials for biomedical applications: A review

Electrospinning is a versatile technique for fabricating polymeric fibers with diameters ranging from micro- to nanoscale, exhibiting multiple morphologies and arrangements. By combining silk fibroin (SF) with synthetic and/or natural polymers, electrospun materials with outstanding biological, chemical, electrical, physical, mechanical, and optical properties can be achieved, fulfilling the evolving biomedical demands. This review highlights the remarkable versatility of SF-derived electrospun materials, specifically focusing on their application in tissue regeneration (including cartilage, cornea, nerves, blood vessels, bones, and skin), disease treatment (such as cancer and diabetes), and the development of controlled drug delivery systems. Additionally, we explore the potential future trends in utilizing these nanofibrous materials for creating intelligent biomaterials, incorporating biosensors and wearable sensors for monitoring human health, and also discuss the bottlenecks for its widespread use. This comprehensive overview illuminates the significant impact and exciting prospects of SF-derived electrospun materials in advancing biomedical research and applications.

Nanomaterials-combined methacrylated gelatin hydrogels (GelMA) for cardiac tissue constructs

Among non-communicable diseases, cardiovascular diseases are the most prevalent, accounting for approximately 17 million deaths per year. Despite conventional treatment, cardiac tissue engineering emerges as a potential alternative for the advancement and treatment of these patients, using biomaterials to replace or repair cardiac tissues. Among these materials, gelatin in its methacrylated form (GelMA) is a biodegradable and biocompatible polymer with adjustable biophysical properties. Furthermore, gelatin has the ability to replace and perform collagen-like functions for cell development in vitro. The interest in using GelMA hydrogels combined with nanomaterials is increasingly growing to promote the responsiveness to external stimuli and improve certain properties of these hydrogels by exploring the incorporation of nanomaterials into these hydrogels to serve as electrical signaling conductive elements. This review highlights the applications of electrically conductive nanomaterials associated with GelMA hydrogels for the development of structures for cardiac tissue engineering, by focusing on studies that report the combination of GelMA with nanomaterials, such as gold and carbon derivatives (carbon nanotubes and graphene), in addition to the possibility of applying these materials in 3D tissue engineering, developing new possibilities for cardiac studies.

Nanotechnology in coronary heart disease

Coronary heart disease (CHD) is one of the major causes of death and disability worldwide, especially in low- and middle-income countries and among older populations. Conventional diagnostic and therapeutic approaches have limitations such as low sensitivity, high cost and side effects. Nanotechnology offers promising alternative strategies for the diagnosis and treatment of CHD by exploiting the unique properties of nanomaterials. In this review, we use bibliometric analysis to identify research hotspots in the application of nanotechnology in CHD and provide a comprehensive overview of the current state of the art. Nanomaterials with enhanced imaging and biosensing capabilities can improve the early detection of CHD through advanced contrast agents and high-resolution imaging techniques. Moreover, nanomaterials can facilitate targeted drug delivery, tissue engineering and modulation of inflammation and oxidative stress, thus addressing multiple aspects of CHD pathophysiology. We discuss the application of nanotechnology in CHD diagnosis (imaging and sensors) and treatment (regulation of macrophages, cardiac repair, anti-oxidative stress), and provide insights into future research directions and clinical translation. This review serves as a valuable resource for researchers and clinicians seeking to harness the potential of nanotechnology in the management of CHD. STATEMENT OF SIGNIFICANCE: Coronary heart disease (CHD) is the one of leading cause of death and disability worldwide. Nanotechnology offers new strategies for diagnosing and treating CHD by exploiting the unique properties of nanomaterials. This review uses bibliometric analysis to uncover research trends in the use of nanotechnology for CHD. We discuss the potential of nanomaterials for early CHD detection through advanced imaging and biosensing, targeted drug delivery, tissue engineering, and modulation of inflammation and oxidative stress. We also offer insights into future research directions and potential clinical applications. This work aims to guide researchers and clinicians in leveraging nanotechnology to improve CHD patient outcomes and quality of life.

Advances in the design, generation, and application of tissue-engineered myocardial equivalents

Due to the limited regenerative ability of cardiomyocytes, the disabling irreversible condition of myocardial failure can only be treated with conservative and temporary therapeutic approaches, not able to repair the damage directly, or with organ transplantation. Among the regenerative strategies, intramyocardial cell injection or intravascular cell infusion should attenuate damage to the myocardium and reduce the risk of heart failure. However, these cell delivery-based therapies suffer from significant drawbacks and have a low success rate. Indeed, cardiac tissue engineering efforts are directed to repair, replace, and regenerate native myocardial tissue function. In a regenerative strategy, biomaterials and biomimetic stimuli play a key role in promoting cell adhesion, proliferation, differentiation, and neo-tissue formation. Thus, appropriate biochemical and biophysical cues should be combined with scaffolds emulating extracellular matrix in order to support cell growth and prompt favorable cardiac microenvironment and tissue regeneration. In this review, we provide an overview of recent developments that occurred in the biomimetic design and fabrication of cardiac scaffolds and patches. Furthermore, we sift in vitro and in situ strategies in several preclinical and clinical applications. Finally, we evaluate the possible use of bioengineered cardiac tissue equivalents as in vitro models for disease studies and drug tests.

Probing interaction of atherogenic lysophosphatidylcholine with functionalized graphene nanosheets: theoretical modelling and experimental validation

CONTEXT

The potential of graphene derivatives for theranostic applications depends on their compatibility with cellular and biomolecular components. Lysophosphatidylcholine (LPC), a lipid component present in oxidized low-density lipoproteins, microvesicles and free circulation in blood, plays a critical role in the pathophysiology of various diseases. Using density functional theory-based methods, we systematically investigated the interaction of atherogenic LPC molecule with different derivatives of graphene, including pristine graphene, graphene with defect, N-doped graphene, amine-functionalized graphene, various graphene oxides and hydroxylated graphene oxides. We observed that the adsorption of LPC on graphene derivatives is highly selective based on the orientation of the functional groups of LPC interacting with the surface of the derivatives. Hydroxylated graphene oxide exhibited the strongest interaction with LPC with adsorption energy of - 2.1 eV due to the interaction between the hydroxyl group on graphene and the phosphate group of LPC. The presence of aqueous medium further enhanced this interaction indicating favourable adsorption of LPC and graphene oxide in biological systems. Such strong interaction leads to substantial change in the electronic structure of the LPC molecule, which results in the activation of this molecule. In contrast, amine-modified graphene showed the least interaction. These theoretical results are in line with our experimental fluorescence spectroscopic data of LPC/1-anilino-8-napthalene sulfonic acid complex. Our present comprehensive investigation employing both theoretical and experimental methods provides a deeper understanding of graphene-lipid interaction, which holds paramount importance in the design and fabrication of graphene-based nanomaterials for biomedical applications.

METHODS

In this study, we employed the density functional theory-based methods to investigate the electronic and structural properties of graphene derivatives and LPC molecule using the Quantum Espresso package. The exchange-correlation functional was described within generalized gradient approximation (GGA) as parameterized by Perdew, Burke and Ernzerhof (PBE). The valence electrons were represented using plane wave basis sets. `The Grimme's dispersion method was used to include the van der Waals dispersion correction.

Potential of graphene-based nanomaterials for cardiac tissue engineering

Cardiovascular diseases are the primary cause of death worldwide. Despite significant advances in pharmacological treatments and surgical interventions to restore heart function after myocardial infarction, it can progress to heart failure due to the restricted inherent potential of adult cardiomyocytes to self-regenerate. Hence, the evolution of new therapeutic methods is critical. Nowadays, novel approaches in tissue engineering have assisted in restoring biological and physical specifications of the injured myocardium and, hence, cardiac function. The incorporation of a supporting matrix that could mechanically and electronically support the heart tissue and stimulate the cells to proliferate and regenerate will be advantageous. Electroconductive nanomaterials can facilitate intracellular communication and aid synchronous contraction via electroactive substrate creation, preventing the issue of arrhythmia in the heart. Among a wide range of electroconductive materials, graphene-based nanomaterials (GBNs) are promising for cardiac tissue engineering (CTE) due to their outstanding features including high mechanical strength, angiogenesis, antibacterial and antioxidant properties, low cost, and scalable fabrication. In the present review, we discuss the effect of applying GBNs on angiogenesis, proliferation, and differentiation of implanted stem cells, their antibacterial and antioxidant properties, and their role in improving the electrical and mechanical properties of the scaffolds for CTE. Also, we summarize the recent research that has applied GBNs in CTE. Finally, we present a concise discussion on the challenges and prospects.

Recent Advances in Tissue-Engineered Cardiac Scaffolds-The Progress and Gap in Mimicking Native Myocardium Mechanical Behaviors

Heart failure is the leading cause of death in the US and worldwide. Despite modern therapy, challenges remain to rescue the damaged organ that contains cells with a very low proliferation rate after birth. Developments in tissue engineering and regeneration offer new tools to investigate the pathology of cardiac diseases and develop therapeutic strategies for heart failure patients. Tissue -engineered cardiac scaffolds should be designed to provide structural, biochemical, mechanical, and/or electrical properties similar to native myocardium tissues. This review primarily focuses on the mechanical behaviors of cardiac scaffolds and their significance in cardiac research. Specifically, we summarize the recent development of synthetic (including hydrogel) scaffolds that have achieved various types of mechanical behavior-nonlinear elasticity, anisotropy, and viscoelasticity-all of which are characteristic of the myocardium and heart valves. For each type of mechanical behavior, we review the current fabrication methods to enable the biomimetic mechanical behavior, the advantages and limitations of the existing scaffolds, and how the mechanical environment affects biological responses and/or treatment outcomes for cardiac diseases. Lastly, we discuss the remaining challenges in this field and suggestions for future directions to improve our understanding of mechanical control over cardiac function and inspire better regenerative therapies for myocardial restoration.

Electroconductive agarose hydrogels modulate mesenchymal stromal cell adhesion and spreading through protein adsorption

Electrically conductive biomaterials direct cell behavior by capitalizing on the effect of bioelectricity in tissue homeostasis and healing. Many studies have leveraged conductive biomaterials to influence cells and improve tissue healing, even in the absence of external stimulation. However, most studies using electroactive materials neglect characterizing how the inclusion of conductive additives affects the material's mechanical properties, and the interplay between substrate electrical and mechanical properties on cell behavior is poorly understood. Furthermore, mechanisms dictating how electrically conductive materials affect cell behavior in the absence of external stimulation are not explicit. In this study, we developed a mechanically and electrically tunable conductive hydrogel using agarose and the conductive polymer PEDOT:PSS. Under certain conditions, we observed that the hydrogel physical and electrical properties were decoupled. We then seeded human mesenchymal stromal cells (MSCs) onto the hydrogels and observed enhanced adhesion and spreading of MSCs on conductive substrates, regardless of the hydrogel mechanical properties, and despite the gels having no cell-binding sites. To explain this observation, we measured protein interaction with the gels and found that charged proteins adsorbed significantly more to conductive hydrogels. These data demonstrate that conductivity promotes cell adhesion, likely by facilitating increased adsorption of proteins associated with cell binding, providing a better understanding of the mechanism of action of electrically conductive materials.

Silk-based conductive materials for smart biointerfaces

Silk-based conductive materials are widely used in biointerface applications, such as artificial epidermal sensors, soft and implantable bioelectronics, and tissue/cell scaffolds. Such biointerface materials require coordinated physicochemical, biological, and mechanical properties to meet current practical needs and future sophisticated demands. However, it remains a challenge to formulate silk-based advanced materials with high electrical conductivity, good biocompatibility, mechanical robustness, and in some cases, tissue adhesion ability without compromising other physicochemical properties. In this review, we highlight recent progress in the development of functional conductive silk-based advanced materials with different morphologies. Then, we reviewed the advanced paradigms of these silk materials applied as wearable flexible sensors, implantable electronics, and tissue/cell engineering with perspectives on the application challenges. Silk-based conductive materials can serve as promising building blocks for biomedical devices in personalized healthcare and other fields of bioengineering.

Conductive fibers for biomedical applications

Bioelectricity has been stated as a key factor in regulating cell activity and tissue function in electroactive tissues. Thus, various biomedical electronic constructs have been developed to interfere with cell behaviors to promote tissue regeneration, or to interface with cells or tissue/organ surfaces to acquire physiological status via electrical signals. Benefiting from the outstanding advantages of flexibility, structural diversity, customizable mechanical properties, and tunable distribution of conductive components, conductive fibers are able to avoid the damage-inducing mechanical mismatch between the construct and the biological environment, in return to ensure stable functioning of such constructs during physiological deformation. Herein, this review starts by presenting current fabrication technologies of conductive fibers including wet spinning, microfluidic spinning, electrospinning and 3D printing as well as surface modification on fibers and fiber assemblies. To provide an update on the biomedical applications of conductive fibers and fiber assemblies, we further elaborate conductive fibrous constructs utilized in tissue engineering and regeneration, implantable healthcare bioelectronics, and wearable healthcare bioelectronics. To conclude, current challenges and future perspectives of biomedical electronic constructs built by conductive fibers are discussed.

Cardiac tissue engineering for myocardial infarction treatment

Myocardial infarction is one of the major causes of morbidity and mortality worldwide. Current treatments can relieve the symptoms of myocardial ischemia but cannot repair the necrotic myocardial tissue. Novel therapeutic strategies based on cellular therapy, extracellular vesicles, non-coding RNAs and growth factors have been designed to restore cardiac function while inducing cardiomyocyte cycle re-entry, ensuring angiogenesis and cardioprotection, and preventing ventricular remodeling. However, they face low stability, cell engraftment issues or enzymatic degradation in vivo, and it is thus essential to combine them with biomaterial-based delivery systems. Microcarriers, nanocarriers, cardiac patches and injectable hydrogels have yielded promising results in preclinical studies, some of which are currently being tested in clinical trials. In this review, we cover the recent advances made in cellular and acellular therapies used for cardiac repair after MI. We present current trends in cardiac tissue engineering related to the use of microcarriers, nanocarriers, cardiac patches and injectable hydrogels as biomaterial-based delivery systems for biologics. Finally, we discuss some of the most crucial aspects that should be addressed in order to advance towards the clinical translation of cardiac tissue engineering approaches.

Microfiber Fabricated via Microfluidic Spinning toward Tissue Engineering Applications

Microfibers, a type of long, thin, and flexible material, can be assembled into functional 3D structures by folding, binding, and weaving. As a novel spinning method, combining microfluidic technology and wet spinning, microfluidic spinning technology can precisely control the size, morphology, structure, and composition of the microfibers. Particularly, the process is mild and rapid, which is suitable for preparing microfibers using biocompatible materials and without affecting the viability of cells encapsulated. Furthermore, owing to the controllability of microfluidic spinning, microfibers with well-defined structures (such as hollow structures) will contribute to the exchange of nutrients or guide cell orientation. Thus, this method is often used to fabricate microfibers as cell scaffolds for cell encapsulation or adhesion and can be further applied to biomimetic fibrous tissues. In this review, the focus is on different fiber structures prepared by microfluidic spinning technology, including solid, hollow, and heterogeneous structures, generated from three essential elements: spinning platform, fiber composition, and solidification methods. Furthermore, the application of microfibers is described with different structures in tissue engineering, such as blood vessels, skeletal muscle, bone, nerves, and lung bronchi. Finally, the challenges and future development prospects of microfluidic spinning technology in tissue engineering applications are discussed.

Chitosan-Based Scaffolds for the Treatment of Myocardial Infarction: A Systematic Review

Cardiovascular diseases (CVD), such as myocardial infarction (MI), constitute one of the world's leading causes of annual deaths. This cardiomyopathy generates a tissue scar with poor anatomical properties and cell necrosis that can lead to heart failure. Necrotic tissue repair is required through pharmaceutical or surgical treatments to avoid such loss, which has associated adverse collateral effects. However, to recover the infarcted myocardial tissue, biopolymer-based scaffolds are used as safer alternative treatments with fewer side effects due to their biocompatibility, chemical adaptability and biodegradability. For this reason, a systematic review of the literature from the last five years on the production and application of chitosan scaffolds for the reconstructive engineering of myocardial tissue was carried out. Seventy-five records were included for review using the "preferred reporting items for systematic reviews and meta-analyses" data collection strategy. It was observed that the chitosan scaffolds have a remarkable capacity for restoring the essential functions of the heart through the mimicry of its physiological environment and with a controlled porosity that allows for the exchange of nutrients, the improvement of the electrical conductivity and the stimulation of cell differentiation of the stem cells. In addition, the chitosan scaffolds can significantly improve angiogenesis in the infarcted tissue by stimulating the production of the glycoprotein receptors of the vascular endothelial growth factor (VEGF) family. Therefore, the possible mechanisms of action of the chitosan scaffolds on cardiomyocytes and stem cells were analyzed. For all the advantages observed, it is considered that the treatment of MI with the chitosan scaffolds is promising, showing multiple advantages within the regenerative therapies of CVD.

An injectable conductive hydrogel restores electrical transmission at myocardial infarct site to preserve cardiac function and enhance repair

Myocardial infarction (MI) leads to massive cardiomyocyte death and deposition of collagen fibers. This fibrous tissue disrupts electrical signaling in the myocardium, leading to cardiac systolic and diastolic dysfunction, as well as arrhythmias. Conductive hydrogels are a promising therapeutic strategy for MI. Here, we prepared a highly water-soluble conductive material (GP) by grafting polypyrrole (PPy) onto non-conductive gelatin. This component was added to the gel system formed by the Schiff base reaction between oxidized xanthan gum (OXG) and gelatin to construct an injectable conductive hydrogel. The prepared self-healing OGGP3 (3 wt% GP) hydrogel had good biocompatibility, elastic modulus, and electrical conductivity that matched the natural heart. The prepared biomaterials were injected into the rat myocardial scar tissue 2 days after MI. We found that the cardiac function of the rats treated with OGGP3 was improved, making it more difficult to induce arrhythmias. The electrical resistivity of myocardial fibrous tissue was reduced, and the conduction velocity of myocardial tissue was increased. Histological analysis showed reduced infarct size, increased left ventricular wall thickness, increased vessel density, and decreased inflammatory response in the infarcted area. Our findings clearly demonstrate that the OGGP3 hydrogel attenuates ventricular remodeling and inhibits infarct dilation, thus showing its potential for the treatment of MI.

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An injectable self-healing conductive hydrogel was synthesized for the treatment of myocardial infarction (MI).

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The OGGP3 hydrogel had elastic modulus (20.77 kPa) and conductivity (5.52 × 10⁻⁴ S/cm) that matched the natural heart.

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The hydrogel could protect cardiac function, reduce arrhythmia susceptibility and the resistivity of cardiac scar tissue.

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The hydrogel could increase left ventricular wall thickness, reduce infarct size and cardiac fibrosis in the infarcted area.

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The hydrogel could promote the expression level of cardiac-specific markers, induce angiogenesis, and reduce inflammation.

The role of major immune cells in myocardial infarction

Myocardial infarction (MI) is a cardiovascular disease (CVD) with high morbidity and mortality worldwide, often leading to adverse cardiac remodeling and heart failure, which is a serious threat to human life and health. The immune system makes an important contribution to the maintenance of normal cardiac function. In the disease process of MI, necrotic cardiomyocytes release signals that activate nonspecific immunity and trigger the action of specific immunity. Complex immune cells play an important role in all stages of MI progression by removing necrotic cardiomyocytes and tissue and promoting the healing of damaged tissue cells. With the development of biomaterials, cardiac patches have become an emerging method of repairing MI, and the development of engineered cardiac patches through the construction of multiple animal models of MI can help treat MI. This review introduces immune cells involved in the development of MI, summarizes the commonly used animal models of MI and the newly developed cardiac patch, so as to provide scientific reference for the accurate diagnosis and effective treatment of MI.

Insight into Heart-Tailored Architectures of Hydrogel to Restore Cardiac Functions after Myocardial Infarction

With permanent heart muscle injury or death, myocardial infarction (MI) is complicated by inflammatory, proliferation and remodeling phases from both the early ischemic period and subsequent infarct expansion. Though in situ re-establishment of blood flow to the infarct zone and delays of the ventricular remodeling process are current treatment options of MI, they fail to address massive loss of viable cardiomyocytes while transplanting stem cells to regenerate heart is hindered by their poor retention in the infarct bed. Equipped with heart-specific mimicry and extracellular matrix (ECM)-like functionality on the network structure, hydrogels leveraging tissue-matching biomechanics and biocompatibility can mechanically constrain the infarct and act as localized transport of bioactive ingredients to refresh the dysfunctional heart under the constant cyclic stress. Given diverse characteristics of hydrogel including conductivity, anisotropy, adhesiveness, biodegradability, self-healing and mechanical properties driving local cardiac repair, we aim to investigate and conclude the dynamic balance between ordered architectures of hydrogels and the post-MI pathological milieu. Additionally, our review summarizes advantages of heart-tailored architectures of hydrogels in cardiac repair following MI. Finally, we propose challenges and prospects in clinical translation of hydrogels to draw theoretical guidance on cardiac repair and regeneration after MI.

A Conductive Bioengineered Cardiac Patch for Myocardial Infarction Treatment by Improving Tissue Electrical Integrity

Conductive scaffolds are of great value for constructing functional myocardial tissues and promoting tissue reconstruction in the treatment of myocardial infarction (MI). Here, a novel scaffold composed of silk fibroin and polypyrrole (SP50) with a typical sponge-like porous structure and electrical conductivity similar to the native myocardium is developed. An electroactive engineered cardiac patch (SP50 ECP) with a certain thickness is constructed by applying electrical stimulation (ES) to the cardiomyocytes (CMs) on the scaffold. SP50 ECP can significantly express cardiac marker protein (α-actinin, Cx-43, and cTnT) and has better contractility and electrical coupling performance. Following in vivo transplantation, SP50 ECP shows a notable therapeutic effect in repairing infarcted myocardium. Not only can SP50 ECP effectively improves left ventricular remodeling and restore cardiac functions, such as ejection function (EF), but more importantly, improves the propagation of electrical pulses and promote the synchronous contraction of CMs in the scar area with normal myocardium, effectively reducing the susceptibility of MI rats to arrhythmias. In conclusion, this study demonstrates a facile approach to constructing electroactive ECPs based on porous conductive scaffolds and proves the therapeutic effects of ECPs in repairing the infarcted heart, which may represent a promising strategy for MI treatment.

Development of Innovative Biomaterials and Devices for the Treatment of Cardiovascular Diseases

Cardiovascular diseases have become the leading cause of death worldwide. The increasing burden of cardiovascular diseases has become a major public health problem and how to carry out efficient and reliable treatment of cardiovascular diseases has become an urgent global problem to be solved. Recently, implantable biomaterials and devices, especially minimally invasive interventional ones, such as vascular stents, artificial heart valves, bioprosthetic cardiac occluders, artificial graft cardiac patches, atrial shunts, and injectable hydrogels against heart failure, have become the most effective means in the treatment of cardiovascular diseases. Herein, an overview of the challenges and research frontier of innovative biomaterials and devices for the treatment of cardiovascular diseases is provided, and their future development directions are discussed.

Bioelectricity-coupling patches for repairing impaired myocardium

Cardiac abnormalities, which account for extensive burdens on public health and economy, drive necessary attempts to revolutionize the traditional therapeutic system. Advances in cardiac tissue engineering have expanded a highly efficacious platform to address cardiovascular events, especially cardiac infarction. Current efforts to overcome biocompatible limitations highlight the constructs of a conductive cardiac patch to accelerate the industrial and clinical landscape that is amenable for patient-accurate therapy, regenerative medicine, disease modeling, and drug delivery. With the notion that cardiac tissue synchronically contracts triggered by electrical pulses, the cardiac patches based on conductive materials are developed and treated on the dysfunctional heart. In this review, we systematically summarize distinct conductive materials serving as the most promising alternatives (conductive nanomaterials, conductive polymers, piezoelectric polymers, and ionic electrolytes) to achieve electric signal transmission and engineered cardiac tissues. Existing applications are discussed considering how these patches containing conductive candidates are fabricated into diverse forms with major strategies. Ultimately, we try to define a new concept as a bioelectricity-coupling patch that provides a favorable cardiac micro-environment for cardiac functional activities. Underlying challenges and prospects are presented regarding industrial processing and cardiovascular treatment of conductive patch progress. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Cardiovascular Disease.

Therapeutic Acellular Scaffolds for Limiting Left Ventricular Remodelling-Current Status and Future Directions

Myocardial infarction (MI) is one of the leading causes of heart-related deaths worldwide. Following MI, the hypoxic microenvironment triggers apoptosis, disrupts the extracellular matrix and forms a non-functional scar that leads towards adverse left ventricular (LV) remodelling. If left untreated this eventually leads to heart failure. Besides extensive advancement in medical therapy, complete functional recovery is never accomplished, as the heart possesses limited regenerative ability. In recent decades, the focus has shifted towards tissue engineering and regenerative strategies that provide an attractive option to improve cardiac regeneration, limit adverse LV remodelling and restore function in an infarcted heart. Acellular scaffolds possess attractive features that have made them a promising therapeutic candidate. Their application in infarcted areas has been shown to improve LV remodelling and enhance functional recovery in post-MI hearts. This review will summarise the updates on acellular scaffolds developed and tested in pre-clinical and clinical scenarios in the past five years with a focus on their ability to overcome damage caused by MI. It will also describe how acellular scaffolds alone or in combination with biomolecules have been employed for MI treatment. A better understanding of acellular scaffolds potentialities may guide the development of customised and optimised therapeutic strategies for MI treatment.

rGO/Silk Fibroin-Modified Nanofibrous Patches Prevent Ventricular Remodeling via Yap/Taz-TGFβ1/Smads Signaling After Myocardial Infarction in Rats

Objective: After acute myocardial infarction (AMI), the loss of cardiomyocytes and dysregulation of extracellular matrix homeostasis results in impaired cardiac function and eventually heart failure. Cardiac patches have emerged as a potential therapeutic strategy for AMI. In this study, we fabricated and produced reduced graphene oxide (rGO)/silk fibroin-modified nanofibrous biomaterials as a cardiac patch to repair rat heart tissue after AMI and investigated the potential role of rGO/silk patch on reducing myocardial fibrosis and improving cardiac function in the infarcted rats. Method: rGO/silk nanofibrous biomaterial was prepared by electrospinning and vacuum filtration. A rat model of AMI was used to investigate the ability of patches with rGO/silk to repair the injured heart in vivo. Echocardiography and stress-strain analysis of the left ventricular papillary muscles was used to assess the cardiac function and mechanical property of injured hearts treated with this cardiac patch. Masson's trichrome staining and immunohistochemical staining for Col1A1 was used to observe the degree of myocardial fibrosis at 28 days after patch implantation. The potential direct mechanism of the new patch to reduce myocardial fibrosis was explored in vitro and in vivo. Results: Both echocardiography and histopathological staining demonstrated improved cardiac systolic function and ventricular remodeling after implantation of the rGO/silk patch. Additionally, cardiac fibrosis and myocardial stiffness of the infarcted area were improved with rGO/silk. On RNA-sequencing, the gene expression of matrix-regulated genes was altered in cardiofibroblasts treated with rGO. Western blot analysis revealed decreased expression of the Yap/Taz-TGFβ1/Smads signaling pathway in heart tissue of the rGO/silk patch group as compared with controls. Furthermore, the rGO directly effect on Col I and Col III expression and Yap/Taz-TGFβ1/Smads signaling was confirmed in isolated cardiofibroblasts in vitro. Conclusion: This study suggested that rGO/silk improved cardiac function and reduced cardiac fibrosis in heart tissue after AMI. The mechanism of the anti-fibrosis effect may involve a direct regulation of rGO on Yap/Taz-TGFβ1/Smads signaling in cardiofibroblasts.

Engineering of injectable hydrogels associate with Adipose-Derived stem cells delivery for anti-cardiac hypertrophy agents

Adipose-derived stem cells (ADSCs) treatment offers support to new methods of transporting baseline cell protein endothelial cells in alginate (A)/silk sericin (SS) lamellar-coated antioxidant system (ASS@L) to promote acute myocardial infarction. In the synthesized frames of ASS, the ratio of fixity modules, pores, the absorption and inflammation was detected at ka (65ka), 151 ± 40.12 μm, 92.8%, 43.2 ± 2.58 and 30.10 ± 2.1. In this context, ADSC-ASS@L was developed and the corresponding material was stable and physically chemical for the development of cardiac regenerative applications. ADSC-ASS@L injectable hydrogels in vitro examination demonstrated higher cell survival rates and pro-angiogenic and pro-Inflammatory expression factors, demonstrating the favorable effect of fractional ejections, fibre-areas, and low infracture vessel densities. In successful cardiac damage therapy in acute myocardial infarction the innovative ADSC injection hydrogel approach may be helpful. The approach could also be effective during coronary artery hypertrophy for successful heart damage treatment.