Angiogenic peptide nanofibers repair cardiac tissue defect after myocardial infarction

Improving therapeutic effects of exosomes encapsulated gelatin methacryloyl/hyaluronic acid blended and oxygen releasing injectable hydrogel by cardiomyocytes induction and vascularization in rat myocardial infarction model

Acute myocardial infarction (AMI) causes acute cardiac cell death when oxygen supply is disrupted. Improving oxygen flow to the damaged area could potentially achieve the to prevent cell death and provide cardiac regeneration. Here, we describe the production of oxygen-producing injectable bio-macromolecular hydrogels from natural polymeric components including gelatin methacryloyl (GelMA), hyaluronic acid (HA) loaded with catalase (CAT). Under hypoxic conditions, the O2-generating hydrogels (O2 (+) hydrogel) encapsulated with Mesenchymal stem cells (MSCs)-derived-exosomes (Exo- O2 (+) hydrogel) released substantial amounts of oxygen for >5 days. We demonstrated that after 7 days of in vitro cell culture, exhibits identical production of paracrine factors compared to those of culture of rat cardiac fibroblasts (RCFs), rat neonatal cardiomyocytes (RNCs) and Human Umbilical Vein Endothelial Cells (HUVECs), demonstrating its ability to replicate the natural architecture and function of capillaries. Four weeks after treatment with Exo-O2 (+) hydrogel, cardiomyocytes in the peri-infarct area of an in vivo rat model of AMI displayed substantial mitotic activity. In contrast with infarcted hearts treated with O2 (-) hydrogel, Exo- O2 (+) hydrogel infarcted hearts showed a considerable increase in myocardial capillary density. The outstanding therapeutic advantages and quick, easy fabrication of Exo- O2 (+) hydrogel has provided promise favourably for potential cardiac treatment applications.

A bibliography of smart nanomaterials biological application in myocardial infarction research

Myocardial infarction has been considered the top cause of mortality globally. Numerous studies investigated the biological application of smart nanomaterials in myocardial infarction. Our study aimed to provide an overview of this area through bibliography research. Literature related to the biological application of nanomaterials was retrieved from the web of science core collection database. Bibliography analysis was performed using Microsoft Excel, VOSviewer, Citespace, and the R package "bibliometrix." A total of 1226 publications were included. The USA, China, and India carried out the most of studies. Harvard University is the most productive institution. Matthias Nahrendorf ranked first in article volume and also owned the highest impact. Keyword burst analysis indicated the frontiers and hotspots to be gold nanoparticles and iron oxide nanoparticles. This bibliography analysis provides a comprehensive overview of uncovered current research trends and emerging hotspots of nanomaterials' biological application in myocardial infarction, thus inspiring further investigations.

Journey into tomorrow: cardiovascular wellbeing transformed by nano-scale innovations

Worldwide, cardiovascular diseases (CVDs) account for the vast majority of deaths and place enormous financial strains on healthcare systems. Gold nanoparticles, quantum dots, polymeric nanoparticles, carbon nanotubes, and lipids are innovative nanomaterials promising in tackling CVDs. In the setting of CVDs, these nanomaterials actively impact cellular responses due to their distinctive properties, including surface energy and topographies. Opportunities to more precisely target CVDs have arisen due to recent developments in nanomaterial science, which have introduced fresh approaches. An in-depth familiarity with the illness and its targeted mechanisms is necessary to use nanomaterials in CVDs effectively. We support the academic community's efforts to prioritize Nano-technological techniques in addressing risk factors linked with cardiovascular diseases, acknowledging the far-reaching effects of these conditions. The significant impact of nanotechnology on the early detection and treatment of cardiovascular diseases highlights the critical need for novel approaches to this pressing health problem, which is affecting people worldwide.

Recent advancements in nanotechnology based drug delivery for the management of cardiovascular disease

Cardiovascular diseases (CVDs) constitute a predominant cause of both global mortality and morbidity. To address the challenges in the early diagnosis and management of CVDs, there is growing interest in the field of nanotechnology and nanomaterials to develop innovative diagnostic and therapeutic approaches. This review focuses on the recent advancements in nanotechnology-based diagnostic techniques, including cardiac immunoassays (CIA), cardiac circulating biomarkers, cardiac exosomal biomarkers, and molecular Imaging (MOI). Moreover, the article delves into the exciting developments in nanoparticles (NPs), biomimetic NPs, nanofibers, nanogels, and nanopatchs for cardiovascular applications. And discuss how these nanoscale technologies can improve the precision, sensitivity, and speed of CVD diagnosis and management. While highlighting their vast potential, we also address the limitations and challenges that must be overcome to harness these innovations successfully. Furthermore, this review focuses on the emerging opportunities for personalized and effective cardiovascular care through the integration of nanotechnology, ultimately aiming to reduce the global burden of CVDs.

Hydrogels for the Treatment of Myocardial Infarction: Design and Therapeutic Strategies

Cardiovascular diseases (CVDs) have become the leading global burden of diseases in recent years and are the primary cause of human mortality and loss of healthy life expectancy. Myocardial infarction (MI) is the top cause of CVDs-related deaths, and its incidence is increasing worldwide every year. Recently, hydrogels have garnered great interest from researchers as a promising therapeutic option for cardiac tissue repair after MI. This is due to their excellent properties, including biocompatibility, mechanical properties, injectable properties, anti-inflammatory properties, antioxidant properties, angiogenic properties, and conductive properties. This review discusses the advantages of hydrogels as a novel treatment for cardiac tissue repair after MI. The design strategies of various hydrogels in MI treatment are then summarized, and the latest research progress in the field is classified. Finally, the future perspectives of this booming field are also discussed at the end of this review.

Recent Progress in Advanced Polyester Elastomers for Tissue Engineering and Bioelectronics

Polyester elastomers are highly flexible and elastic materials that have demonstrated considerable potential in various biomedical applications including cardiac, vascular, neural, and bone tissue engineering and bioelectronics. Polyesters are desirable candidates for future commercial implants due to their biocompatibility, biodegradability, tunable mechanical properties, and facile synthesis and fabrication methods. The incorporation of bioactive components further improves the therapeutic effects of polyester elastomers in biomedical applications. In this review, novel structural modification methods that contribute to outstanding mechanical behaviors of polyester elastomers are discussed. Recent advances in the application of polyester elastomers in tissue engineering and bioelectronics are outlined and analyzed. A prospective of the future research and development on polyester elastomers is also provided.

Peptide-Protein Coassemblies into Hierarchical and Bioactive Tubular Membranes

Multicomponent self-assembly offers opportunities for the design of complex and functional biomaterials with tunable properties. Here, we demonstrate how minor modifications in the molecular structures of peptide amphiphiles (PAs) and elastin-like recombinamers (ELs) can be used to generate coassembling tubular membranes with distinct structures, properties, and bioactivity. First, by introducing minor modifications in the charge density of PA molecules (PAK2, PAK3, PAK4), different diffusion-reaction processes can be triggered, resulting in distinct membrane microstructures. Second, by combining different types of these PAs prior to their coassembly with ELs, further modifications can be achieved, tuning the structures and properties of the tubular membranes. Finally, by introducing the cell adhesive peptide RGDS in either the PA or EL molecules, it is possible to harness the different diffusion-reaction processes to generate tubular membranes with distinct bioactivities. The study demonstrates the possibility to trigger and achieve minor but crucial differences in coassembling processes and tune material structure and bioactivity. The study demonstrates the possibility to use minor, yet crucial, differences in coassembling processes to tune material structure and bioactivity.

Direct Observation of Adhesion and Mechanical Behavior of a Single Poly(lactic-co-glycolic acid) (PLGA) Fiber Using an In Situ Technique for Tissue Engineering

Nanometer- and submicrometer-sized fiber have been used as scaffolds for tissue engineering, because of their fundamental load-bearing properties in synergy with mechano-transduction. This study investigates a single biodegradable poly(lactic-co-glycolic acid) (PLGA) fiber's load-displacement behavior utilizing the nanoindentation technique coupled with a high-resolution in situ imaging system. It is demonstrated that a maximum force of ∼3 μN in the radial direction and displacement of at least 150% of fiber diameter should be applied to acquire the fiber's macroscopic mechanical properties for tissue engineering. The adhesion behavior of a single fiber is captured using a high-resolution camera. The digital image correlation (DIC) technique is adopted to quantify the adhesion force (∼25 μN) between the fiber and the tip. Adhesion force has also been quantified for the fiber after immersing in phosphate-buffered saline (PBS) to mimic the bioenvironment. A 4-fold increase in adhesion force after PBS treatment was observed due to water penetration and hydrolysis on the fiber's surface. A high similarity between mechanical properties of a single fiber and native tissues (elastic modulus of 10-25 kPa) and superior adhesion force (25-107.25 μN) was observed, which is excellent for promoting cell-matrix communication. Overall, this study examines the mechanics of a single fiber using innovative indentation and imaging processing techniques, disclosing its profound and striking roles in tissue engineering.

Peptide Biomaterials for Tissue Regeneration

Expanding the toolbox of therapeutic materials for soft tissue and organ repair has become a critical component of tissue engineering. While animal- and plant-derived proteins are the foundation for developing biomimetic tissue constructs, using peptides as either constituents or frameworks for the materials has gained increasing momentum in recent years. This mini review discusses recent advances in peptide-based biomaterials’ design and application. We also discuss some of the future challenges posed and opportunities opened by peptide-based structures in the field of tissue engineering and regenerative medicine.

Nanomaterials: A Promising Therapeutic Approach for Cardiovascular Diseases

Cardiovascular diseases (CVDs) are a primary cause of death globally. A few classic and hybrid treatments exist to treat CVDs. However, they lack in both safety and effectiveness. Thus, innovative nanomaterials for disease diagnosis and treatment are urgently required. The tiny size of nanomaterials allows them to reach more areas of the heart and arteries, making them ideal for CVDs. Atherosclerosis causes arterial stenosis and reduced blood flow. The most common treatment is medication and surgery to stabilize the disease. Nanotechnologies are crucial in treating vascular disease. Nanomaterials may be able to deliver medications to lesion sites after being infused into the circulation. Newer point-of-care devices have also been considered together with nanomaterials. For example, this study will look at the use of nanomaterials in imaging, diagnosing, and treating CVDs.

New Forms of Electrospun Nanofibers Applied in Cardiovascular Field

Cardiovascular disease (CVD) is one of the leading causes of death worldwide. In recent years, regenerative medicine, tissue engineering and the development of new materials have become the focus of attention this field, and electrospinning technology to prepare nanofibrous materials for the treatment of cardiovascular diseases has attracted people's attention. Unlike previous reviews, this research enumerates the experimental methods and applications of electrospinning technology combined with nanofibrous materials in the directions of myocardial infarction repair, artificial heart valves, artificial blood vessels and cardiovascular patches from the perspective of cardiovascular surgery. In the end, this review also summarizes the limitations, unresolved technical challenges, and possible future directions of this technology for cardiovascular disease applications.

Advances in Nanomaterials for Injured Heart Repair

Atherosclerotic cardiovascular disease (ASCVD) is one of the leading causes of mortality worldwide. Because of the limited regenerative capacity of adult myocardium to compensate for the loss of heart tissue after ischemic infarction, scientists have been exploring the possible mechanisms involved in the pathological process of ASCVD and searching for alternative means to regenerate infarcted cardiac tissue. Although numerous studies have pursued innovative solutions for reversing the pathological process of ASCVD and improving the effectiveness of delivering therapeutics, the translation of those advances into downstream clinical applications remains unsatisfactory because of poor safety and low efficacy. Recently, nanomaterials (NMs) have emerged as a promising new strategy to strengthen both the efficacy and safety of ASCVD therapy. Thus, a comprehensive review of NMs used in ASCVD treatment will be useful. This paper presents an overview of the pathophysiological mechanisms of ASCVD and the multifunctional mechanisms of NM-based therapy, including antioxidative, anti-inflammation and antiapoptosis mechanisms. The technological improvements of NM delivery are summarized and the clinical transformations concerning the use of NMs to treat ASCVD are examined. Finally, this paper discusses the challenges and future perspectives of NMs in cardiac regeneration to provide insightful information for health professionals on the latest advancements in nanotechnologies for ASCVD treatment.

Injectable oligomer-cross-linked gelatine hydrogels via anhydride-amine-conjugation

Injectable gelatine-based hydrogels are valuable tools for drug and cell delivery due to their extracellular matrix-like properties that can be adjusted by the degree of cross-linking. We have established anhydride-containing oligomers for the cross-linking of gelatine via anhydride-amine-conjugation. So far, this conversion required conditions not compatible with cell encapsulation or in vivo injection. In order to overcome this limitation, we developed an array of quarter-oligomers varying in comonomer composition and contents of reactive anhydride units reactive towards amine groups under physiological conditions. The oligomers were of low molecular weight (Mn < 5 kDa) with a high degree of chemically intact anhydrides. Chemical comonomer composition was determined by 1H-NMR. Dissolutions experiments confirmed improved hydrophilicity of the synthesized oligomers over our established compositions. Injectable formulations are described utilizing cytocompatible concentrations of constituent materials and proton-scavenging base. Degree of cross-linking and stiffness of injectable hydrogels were controlled by composition. The gels hold promise as injectable drug or cell carrier and as bioink.

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.

Silencing long non-coding RNA MIAT ameliorates myocardial dysfunction induced by myocardial infarction via MIAT/miR-10a-5p/EGR2 axis

Long non-coding RNA (lncRNA) myocardial infarction-associated transcript (MIAT) has been widely-demonstrated to function as diagnostic markers for acute myocardial infarction (MI). This study was designed to explore the modulatory role of MIAT and its underlying molecular mechanism in MI. Firstly, MI mouse model was developed via ligation of the descending branch of the left coronary artery, and cell model was established through exposure to hypoxic conditions. Online prediction indicated that MIAT could bind to microRNA-10a-5p (miR-10a-5p), while miR-10a-5p was highlighted to bind to early growth response gene-2 (EGR2). MIAT and EGR2 were subsequently determined to be highly-expressed, whereas miR-10a-5p was found to be poorly-expressed in cardiomyocytes exposed to hypoxia as well as in MI mice using RT-qPCR and Western blot assay. The binding relationships between MIAT and miR-10a-5p, and between miR-10a-5p and EGR2 were further confirmed by dual-luciferase reporter and RNA immunoprecipitation assays. The results of in vitro and in vivo experimentation also suggested that overexpression of miR-10a-5p or silencing of MIAT and EGR2 reduced cardiomyocyte apoptosis and increased ATP content, thus alleviating the impairment of cardiac function following MI. In a word, inhibition of MIAT protects against cardiac dysfunction induced by MI through the crosstalk with miR-10a-5p/EGR2.

The protective effects of memantine against inflammation and impairment of endothelial tube formation induced by oxygen-glucose deprivation/reperfusion

Acute myocardial infarction (AMI) is one of the leading causes of death and disability. The dysregulation of cardiac endothelial cells plays a significant role in the pathogenesis of AMI. In the present study, we investigated the potential of memantine, a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist used in the treatment of Alzheimer's disease, to mitigate the effects of ischemia-reperfusion injury in the peripheral vasculature using human umbilical cord endothelial cells (HUVECs). Previous studies have identified anti-inflammatory and antioxidant effects of memantine, but the effects of memantine on angiogenesis and microtubule formation have not been fully elucidated. Our findings indicate that pretreatment with memantine significantly reduced the expression of interleukin (IL)-6 and IL-8, which are both serum markers if AMI severity. We also demonstrate that memantine could prevent mitochondrial dysfunction and oxidative stress by rescuing mitochondrial membrane potential and reducing the production of reactive oxygen species (ROS) by NADPH oxidase-4 (NOX-4). Importantly, memantine also promoted the expression of the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) antioxidant signaling pathway. Importantly, memantine pretreatment improved cell viability and prevented the decrease in microtubule formation induced by OGD/R. Through a phosphoinositide-3-kinase (PI3K) inhibition experiment, we determined that the PI3K/protein kinase B (Akt) pathway is essential for the effects of memantine on angiogenesis. Together, our findings suggest a potential role for memantine in the prevention and treatment of AMI.

Biomaterials Loaded with Growth Factors/Cytokines and Stem Cells for Cardiac Tissue Regeneration

Myocardial infarction causes cardiac tissue damage and the release of damage-associated molecular patterns leads to activation of the immune system, production of inflammatory mediators, and migration of various cells to the site of infarction. This complex response further aggravates tissue damage by generating oxidative stress, but it eventually heals the infarction site with the formation of fibrotic tissue and left ventricle remodeling. However, the limited self-renewal capability of cardiomyocytes cannot support sufficient cardiac tissue regeneration after extensive myocardial injury, thus, leading to an irreversible decline in heart function. Approaches to improve cardiac tissue regeneration include transplantation of stem cells and delivery of inflammation modulatory and wound healing factors. Nevertheless, the harsh environment at the site of infarction, which consists of, but is not limited to, oxidative stress, hypoxia, and deficiency of nutrients, is detrimental to stem cell survival and the bioactivity of the delivered factors. The use of biomaterials represents a unique and innovative approach for protecting the loaded factors from degradation, decreasing side effects by reducing the used dosage, and increasing the retention and survival rate of the loaded cells. Biomaterials with loaded stem cells and immunomodulating and tissue-regenerating factors can be used to ameliorate inflammation, improve angiogenesis, reduce fibrosis, and generate functional cardiac tissue. In this review, we discuss recent findings in the utilization of biomaterials to enhance cytokine/growth factor and stem cell therapy for cardiac tissue regeneration in small animals with myocardial infarction.

Peptide gels for controlled release of proteins

Treatment strategies in clinics have been shifting from small molecules to protein drugs due to the promising results of a highly specific mechanism of action and reduced toxicity. Despite their prominent roles in disease treatment, delivery of the protein therapeutics is challenging due to chemical instability, immunogenicity and biological barriers. Peptide hydrogels with spatiotemporally tunable properties have shown an outstanding potential to deliver complex protein therapeutics, maintain drug efficacy and stability over time, mimicking the extracellular matrix, and responding to external stimuli. In this review, we present recent advances in peptide hydrogel design strategies, protein release kinetics and mechanisms for protein drug delivery in cellular engineering, tissue engineering, immunotherapy and disease treatments.

Engineered bioactive nanoparticles incorporated biofunctionalized ECM/silk proteins based cardiac patches combined with MSCs for the repair of myocardial infarction: In vitro and in vivo evaluations

The development of cardiac patches by the combination of bioactive nano- and bio-materials with mesenchymal stem cells signifies an auspicious approach for the treatment of cardiac repair in myocardial infarction. In the present investigation, we study about the cardiac function of morphology improved gold nanoparticles combined with extracellular matrix/silk proteins for the cell proliferation and expansion of cardiomyocytes. The physico-chemical and morphological characteristics demonstrated that spherical and homogeneous Au particles are distributed on the matrix porous surface for providing favorable conductivity and biological influences in cardiac repair. The in vitro cell studies of prepared patches have established enhanced cell compatibility and retention of cardiomyocytes survival. The in vivo determinations imply that Au-ESF group decreases infarct size to 65% from 89% in control group. These developed cardiac patches can be highly suitable in the cardiac regeneration and offer new platform in cardiac tissue engineering.

A Cell-Free SDKP-Conjugated Self-Assembling Peptide Hydrogel Sufficient for Improvement of Myocardial Infarction

Biomaterials in conjunction with stem cell therapy have recently attracted attention as a new therapeutic approach for myocardial infarction (MI), with the aim to solve the delivery challenges that exist with transplanted cells. Self-assembling peptide (SAP) hydrogels comprise a promising class of synthetic biomaterials with cardiac-compatible properties such as mild gelation, injectability, rehealing ability, and potential for sequence modification. Herein, we developed an SAP hydrogel composed of a self-assembling gel-forming core sequence (RADA) modified with SDKP motif with pro-angiogenic and anti-fibrotic activity to be used as a cardioprotective scaffold. The RADA-SDKP hydrogel was intramyocardially injected into the infarct border zone of a rat model of MI induced by left anterior descending artery (LAD) ligation as a cell-free or a cell-delivering scaffold for bone marrow mesenchymal stem cells (BM-MSCs). The left ventricular ejection fraction (LVEF) was markedly improved after transplantation of either free hydrogel or cell-laden hydrogel. This cardiac functional repair coincided very well with substantially lower fibrotic tissue formation, expanded microvasculature, and lower inflammatory response in the infarct area. Interestingly, BM-MSCs alone or in combination with hydrogel could not surpass the cardiac repair effects of the SDKP-modified SAP hydrogel. Taken together, we suggest that the RADA-SDKP hydrogel can be a promising cell-free construct that has the capability for functional restoration in the instances of acute myocardial infarction (AMI) that might minimize the safety concerns of cardiac cell therapy and facilitate clinical extrapolation.

Recent advances in biomaterials for 3D scaffolds: A review

Considering the advantages and disadvantages of biomaterials used for the production of 3D scaffolds for tissue engineering, new strategies for designing advanced functional biomimetic structures have been reviewed. We offer a comprehensive summary of recent trends in development of single- (metal, ceramics and polymers), composite-type and cell-laden scaffolds that in addition to mechanical support, promote simultaneous tissue growth, and deliver different molecules (growth factors, cytokines, bioactive ions, genes, drugs, antibiotics, etc.) or cells with therapeutic or facilitating regeneration effect. The paper briefly focuses on divers 3D bioprinting constructs and the challenges they face. Based on their application in hard and soft tissue engineering, in vitro and in vivo effects triggered by the structural and biological functionalized biomaterials are underlined. The authors discuss the future outlook for the development of bioactive scaffolds that could pave the way for their successful imposing in clinical therapy.

Current progress in application of polymeric nanofibers to tissue engineering

Tissue engineering uses a combination of cell biology, chemistry, and biomaterials to fabricate three dimensional (3D) tissues that mimic the architecture of extracellular matrix (ECM) comprising diverse interwoven nanofibrous structure. Among several methods for producing nanofibrous scaffolds, electrospinning has gained intense interest because it can make nanofibers with a porous structure and high specific surface area. The processing and solution parameters of electrospinning can considerably affect the assembly and structural morphology of the fabricated nanofibers. Electrospun nanofibers can be made from natural or synthetic polymers and blending them is a straightforward way to tune the functionality of the nanofibers. Furthermore, the electrospun nanofibers can be functionalized with various surface modification strategies. In this review, we highlight the latest achievements in fabricating electrospun nanofibers and describe various ways to modify the surface and structure of scaffolds to promote their functionality. We also summarize the application of advanced polymeric nanofibrous scaffolds in the regeneration of human bone, cartilage, vascular tissues, and tendons/ligaments.

Peptide-Based Functional Biomaterials for Soft-Tissue Repair

Synthetically derived peptide-based biomaterials are in many instances capable of mimicking the structure and function of their full-length endogenous counterparts. Combine this with the fact that short mimetic peptides are easier to produce when compared to full length proteins, show enhanced processability and ease of modification, and have the ability to be prepared under well-defined and controlled conditions; it becomes obvious why there has been a recent push to develop regenerative biomaterials from these molecules. There is increasing evidence that the incorporation of peptides within regenerative scaffolds can result in the generation of structural recognition motifs that can enhance cell attachment or induce cell signaling pathways, improving cell infiltration or promote a variety of other modulatory biochemical responses. By highlighting the current approaches in the design and application of short mimetic peptides, we hope to demonstrate their potential in soft-tissue healing while at the same time drawing attention to the advances made to date and the problems which need to be overcome to advance these materials to the clinic for applications in heart, skin, and cornea repair.

Cardioprotection of salvianolic acid B and ginsenoside Rg1 combination on subacute myocardial infarction and the underlying mechanism

BACKGROUND

Following myocardial infarction (MI), a series of structural and functional changes evolves in the myocardium, collectively defined as cardiac remodeling.

PURPOSE

The aim of present study was to investigate the cardioprotection of salvianolicacid B (SalB) and ginsenoside Rg1 (Rg1) combination against cardiac remodeling in a rat model at the subacute phase of MI and further elucidate the underlying mechanism.

METHODS

Rat heart was exposed via a left thoracotomy at the fourth intercostal space and MI was induced by a ligature below the left descending coronary artery. Hemodynamic assay was conducted using a Mikro-tipped SPR-320 catheter which was inserted through the right carotid artery into left ventricle.Myocardial infarct size was detected using 3,5-triphenyltetrazolium chloride (TTC) staining. Haematoxylin and eosin (HE) stain and picric sirius red stain were conducted for histopathological detection. Immunohistochemistry was used to detect the expression of α-smooth muscle actin (α-SMA) and gelatin zymography was used to evaluate the activities of matrix metalloproteinase-9 (MMP-9).

RESULTS

Comparing with MI rats, 30 mg/kg SalB-Rg1 improved cardiac function verified by maximum rate of pressure development for contraction (+dp/dt_max, p < 0.01) and maximum rate of pressure development for relaxation (-dp/dt_max, p < 0.05); reduced myocardial infarct size (p < 0.05) verified by TTC staining, improved cardiac structure based on HE stain; decreased collagen volume fraction (p < 0.05) and collagen I/III ratio (p < 0.05) according picrosirius red staining. The underlying mechanism of SalB-Rg1 against cardiac remodeling was associated with its down-regulation on α-SMA expression according immunohistochemistry (p < 0.01) and inhibition on MMP-9 activity based on in-gel zymography (p < 0.05).

CONCLUSION

All above study indicated the potential therapeutic effects of SalB-Rg1 on heart.

A collagen hydrogel loaded with HDAC7-derived peptide promotes the regeneration of infarcted myocardium with functional improvement in a rodent model

Myocardial infarction (MI) leads to the loss of cardiomyocytes, left ventricle (LV) dilation, and cardiac dysfunction, eventually developing into heart failure. Most of the strategies for MI therapy require biomaterials that can support tissue regeneration. In this study, we hypothesized that the extracellular matrix (ECM)-derived collagen I hydrogel loaded with histone deacetylase 7 (HDAC7)-derived-phosphorylated 7-amino-acid peptide (7Ap) could restrain LV remodeling and improve cardiac function after MI. An MI model was established by ligation of the left anterior descending coronary artery (LAD) of C57/B6 mice. The 7Ap-loaded collagen I hydrogel was intramyocardially injected to the infarcted region of the LV wall of the heart. After local delivery, the 7Ap-collagen increased neo-microvessel formation, enhanced stem cell antigen-1 positive (Sca-1⁺) stem cell recruitment and differentiation, decreased cellular apoptosis, and promoted cardiomyocyte cycle progression. Furthermore, the 7Ap-collagen restricted the fibrosis of the LV wall, reduced the infarct wall thinning, and improved cardiac performance significantly at 2 weeks post-MI. These results highlight the promising implication of 7Ap-collagen as a novel candidate for MI therapy. STATEMENT OF SIGNIFICANCE: The mammalian myocardium has a limited regenerative capability following myocardial infarction (MI). MI leads to extensive loss of cardiomyocytes, thus culminating in adverse cardiac remodeling and congestive heart failure. In situ tissue regeneration through endogenous cell mobilization has great potential for tissue regeneration. A 7-amino-acid-peptide (7A) domain encoded by a short open-reading frame (sORF) of the HDAC7 gene. The phosphorylated from of 7A (7Ap) has been reported to promote in situ tissue repair via the mobilization and recruitment of endogenous stem cell antigen-1 positive (Sca-l⁺) stem cells. In this study, 7Ap was shown to improve H9C2 cell survival, in vitro. In vivo investigations in a mouse MI model demonstrated that intra-myocardial delivery of 7Ap-loaded collagen hydrogel promoted neovascularization, stimulated Sca-l⁺ stem cell recruitment and differentiation, reduced cardiomyocyte apoptosis and promoted cell cycle progression. As a result, treated infarcted hearts had increased wall thickness, had improved heart function and exhibited attenuation of adverse cardiac remodeling, observed for up to 2 weeks. Overall, these results highlighted the positive impact of implanting 7Ap-collagen as a novel constituent for MI repair.

In Situ Gelling Scaffolds Loaded with Platelet Growth Factors to Improve Cardiomyocyte Survival after Ischemia

Myocardial infarction is caused by prolonged ischemia and it is one of the main cause that leads to heart failures. The aim of the present work was the development of in situ gelling systems, based on poloxamer 407 (P407) or sodium alginate (Alg), loaded with platelet lysate (PL) to enhance cardiomyocyte survival after ischemia. Chondroitin sulfate (CS), a negatively charged glycosaminoglycan able to interact with different positively charged bioactive molecules, such as growth factors, was also investigated with both the systems. The gelation properties of both systems (viscosity, viscoelasticity, consistency by means of penetrometry, and injectability) were characterized in a physiological environment. In vitro evaluation of biocompatibility using fetal cardiac cells (cardiomyocytes and cardiac fibroblasts) demonstrated that the PL loaded alginate/chondroitin sulfate system retained the highest number of viable cells with equal distribution of the populations of cardiomyocytes and fibroblasts. Furthermore, the ability of the systems to improve cardiomyocyte survival after ischemia was also assessed. PL allowed for the highest degree of survival of cardiomyocytes after oxidative damage (simulating ischemic conditions due to MI) and both the Alg + CS PL and, to a greater extent, the PL alone demonstrated a considerable increase in survival of cardiomyocytes. In conclusion, an in situ gelling alginate-chondroitin sulfate system, loaded with platelet lysate, was able to improve the survival of cardiomyocytes after oxidative damage resulting in a promising system to improve cardiac cell viability after ischemia.