Materials For Cardiac Tissue Engineering Research Articles

Recent advances in tailoring stimuli-responsive hybrid scaffolds for cardiac tissue engineering and allied applications.

To recapitulate bio-physical properties and functional behaviour of native heart tissues, recent tissue engineering-based approaches are focused on developing smart/stimuli-responsive materials for interfacing cardiac cells. Overcoming the drawbacks of the traditionally used biomaterials, these smart materials portray outstanding mechanical and conductive properties while promoting cell-cell interaction and cell-matrix transduction cues in such excitable tissues. To date, a large number of stimuli-responsive materials have been employed for interfacing cardiac tissues alone or in combination with natural/synthetic materials for cardiac tissue engineering. However, their comprehensive classification and a comparative analysis of the role played by these materials in regulating cardiac cell behaviour and in vivo metabolism are much less discussed. In an attempt to cover the recent advances in fabricating stimuli-responsive biomaterials for engineering cardiac tissues, this review details the role of these materials in modulating cardiomyocyte behaviour, functionality and surrounding matrix properties. Furthermore, concerns and challenges regarding the clinical translation of these materials and the possibility of using such materials for the fabrication of bio-actuators and bioelectronic devices are discussed.

Recent advances in implantable hydrogels for treating heart failure

AbstractHeart failure (HF) is an irreversible disease characterized by the reducing capacity of blood supply as a consequence of cardiomyocyte death and deteriorated fibrosis. There is a lack of effective treatment for heart failure other than a heart transplant, and thus significant resources have been dedicated to developing functional materials for cardiac tissue engineering. Implanting hydrogels in the myocardium near the myocardial infarction area can preserve cardiac function and slow the remodeling that leads to HF by providing mechanical support to the ventricular wall. Nevertheless, few reviews have been published for this promising HF treatment. Herein, we briefly discuss the classification and existing conventional treatments for HF and provide an overview of recent functional hydrogels designed for cardiac repair after myocardial infarction, including polymeric hydrogels, polymer‐cell complex hydrogels, polymer‐cytokine complex hydrogels, and polymer‐protein complex hydrogels. Key challenges and future directions for advanced hydrogels have also been discussed.

Recent Advances in Designing Electroconductive Biomaterials for Cardiac Tissue Engineering.

Implantable cardiac patches and injectable hydrogels are among the most promising therapies for cardiac tissue regeneration following myocardial infarction. Incorporating electrical conductivity into these patches and hydrogels is found to be an efficient method to improve cardiac tissue function. Conductive nanomaterials such as carbon nanotube, graphene oxide, gold nanorod, as well as conductive polymers such as polyaniline, polypyrrole, and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate are appealing because they possess the electroconductive properties of semiconductors with ease of processing and have potential to restore electrical signaling propagation through the infarct area. Numerous studies have utilized these materials for regeneration of biological tissues that possess electrical activities, such as cardiac tissue. In this review, recent studies on the use of electroconductive materials for cardiac tissue engineering and their fabrication methods are summarized. Moreover, recent advances in developing electroconductive materials for delivering therapeutic agents as one of emerging approaches for treating heart diseases and regenerating damaged cardiac tissues are highlighted.

Ionic liquid-based electroactive materials: a novel approach for cardiac tissue engineering strategies.

Cardiac tissue regeneration strategies are increasingly taking advantage of electroactive scaffolds to actively recreate the tissue microenvironment. In this context, this work reports on advanced materials based on two different ionic liquids (ILs), 2-hydroxyethyl-trimethylammonium dihydrogen phosphate ([Ch][DHP]) and choline bis(trifluoromethylsulfonyl)imide ([Ch][TFSI]), combined with poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) for the development of ionic electroactive IL/polymer hybrid materials for cardiac tissue engineering (TE). The morphological, physico-chemical, thermal and electrical properties of the hybrid materials, as well as their potential use as scaffolds for cardiac TE applications, were evaluated. Besides inducing changes in surface topography, roughness and wettability of the composites, the incorporation of [Ch][DHP] and [Ch][TFSI] leads to the increase in surface (σsurface) and volume (σvolume) electrical conductivities. Furthermore, washing the hybrid samples with phosphate-buffered saline solution strongly decreases the σsurface, whereas σsurface and σvolume of the composites remain almost unaltered after exposure to ultraviolet sterilization treatment. Additionally, it is verified that the incorporation of IL influences the P(VDF-TrFE) microstructure and crystallization process, acting as a defect during its crystallization. Cytotoxicity assays revealed that hybrid films based on [Ch][DHP] alone are not cytotoxic. These films also support H9c2 myoblast cell adhesion and proliferation, demonstrating their suitability for cardiac TE strategies based on electroactive microenvironments.

Recombinant spider silk protein eADF4(C16)-RGD coatings are suitable for cardiac tissue engineering

Cardiac tissue engineering is a promising approach to treat cardiovascular diseases, which are a major socio-economic burden worldwide. An optimal material for cardiac tissue engineering, allowing cardiomyocyte attachment and exhibiting proper immunocompatibility, biocompatibility and mechanical characteristics, has not yet emerged. An additional challenge is to develop a fabrication method that enables the generation of proper hierarchical structures and constructs with a high density of cardiomyocytes for optimal contractility. Thus, there is a focus on identifying suitable materials for cardiac tissue engineering. Here, we investigated the interaction of neonatal rat heart cells with engineered spider silk protein (eADF4(C16)) tagged with the tripeptide arginyl-glycyl-aspartic acid cell adhesion motif RGD, which can be used as coating, but can also be 3D printed. Cardiomyocytes, fibroblasts, and endothelial cells attached well to eADF4(C16)-RGD coatings, which did not induce hypertrophy in cardiomyocytes, but allowed response to hypertrophic as well as proliferative stimuli. Furthermore, Kymograph and MUSCLEMOTION analyses showed proper cardiomyocyte beating characteristics on spider silk coatings, and cardiomyocytes formed compact cell aggregates, exhibiting markedly higher speed of contraction than cardiomyocyte mono-layers on fibronectin. The results suggest that eADF4(C16)-RGD is a promising material for cardiac tissue engineering.

From biomimicry to bioelectronics: Smart materials for cardiac tissue engineering

Effective strategies in cardiac tissue engineering require matrices that recapitulate the mechanical, topographic and electrical cues present in the native extracellular matrix. In this review, we discuss recent efforts in materials science and nanotechnology to achieve functional three-dimensional (3D) scaffolds that modulate and monitor cardiac tissue function. We consider key design considerations, including choice of biopolymer matrix, cell sources, and delivery methods for eventual therapies. We then discuss how solid-state nanomaterials may be integrated within these systems to provide unique electrical and nanotopographic cues that improve electromechanical synchrony. We describe how these approaches may be extended to complex, spatially heterogeneous constructs using 3D bioprinting techniques. Finally, we describe how scaffold materials may be augmented with bioelectronic components to achieve hybrid myocardium that monitors or controls electrophysiological activity. Collectively, these approaches provide a framework for achieving cardiac tissues with tunable, rationally-designed functionalities. We discuss future prospects and remaining challenges for clinical translation.

Nanofibrous Composite with Tailorable Electrical and Mechanical Properties for Cardiac Tissue Engineering

AbstractCardiac tissue engineering is a promising strategy to prevent functional deterioration or even to enhance cardiac function upon myocardial infarction. Here, electrospun fiber mats containing different combinations of electrically conductive polyaniline, collagen, and/or hyaluronic acid are assessed regarding material properties and compatibility with cardiomyocyte attachment and function. Microstructure analysis reveals that collagen fiber mats contain a wide range of fiber diameters after crosslinking (from ≈300 nm to ≈5 µm); all other fiber mats contain fibers in the range of ≈120 to ≈300 nm. Fiber mats exhibit comparable electrical conductivity to and greater mechanical properties than the native human myocardium, which is considered beneficial. Cell–matrix interaction analysis utilizing postnatal rat cardiomyocytes reveals that the fiber mats are non‐cytotoxic and permit cell attachment and contraction. Fiber mats containing collagen (9.89%), hyaluronic acid (1.1%), and polyaniline (PANi, 1.34%) exhibit the most favorable properties with longer contraction time, higher contractile amplitude, and lower beating rates. Improved contraction is accompanied by increased connexin 43 expression. Importantly, this fiber mat is a suitable material for human‐induced pluripotent stem cell–derived cardiomyocytes regarding cytotoxicity, cell attachment, and function. Collectively, these data demonstrate that fiber mats made of collagen, hyaluronic acid, and polyaniline are promising materials for cardiac tissue engineering.

Channeled ECM-Based Nanofibrous Hydrogel for Engineering Vascularized Cardiac Tissues.

Hydrogels are widely used materials for cardiac tissue engineering. However, once the cells are encapsulated within hydrogels, mass transfer to the core of the engineered tissue is limited, and cell viability is compromised. Here, we report on the development of a channeled ECM-based nanofibrous hydrogel for engineering vascularized cardiac tissues. An omentum hydrogel was mixed with cardiac cells, patterned to create channels and closed, and then seeded with endothelial cells to form open cellular lumens. A mathematical model was used to evaluate the necessity of the channels for maintaining cell viability and the true potential of the vascularized hydrogel to form a viable cardiac patch was studied.

Optimizing Blended Collagen-Fibrin Hydrogels for Cardiac Tissue Engineering with Human iPSC-derived Cardiomyocytes.

Natural polymer hydrogels are used ubiquitously as scaffold materials for cardiac tissue engineering as well as for soft tissue engineering more broadly because of FDA approval, minimal immunogenicity, and well-defined physiological clearance pathways. However, the relationships between natural polymer hydrogels and resident cell populations in directing the development of engineered tissues are poorly defined. This interaction is of particular concern for tissues prepared with iPSC-derived cell populations, in which population purity and batch-to-batch variability become additional critical factors to consider. Herein, the design space for a blended fibrin and collagen scaffold is characterized for applications in creating engineered myocardium with human iPSC-derived cardiomyocytes. Stiffness values of the acellular hydrogel formulations approach those of native myocardium in compression, but deviate significantly in tension when compared to rat myocardium in both transverse and longitudinal fiber orientations. A response surface methodology approach to understanding the relationship between collagen concentration, fibrin concentration, seeding density, and cardiac purity found a statistically significant predictive model across three repeated studies that confirms that all of these factors contribute to tissue compaction. In these constructs, increased fibrin concentration and seeding density were each associated with increased compaction, while increased collagen concentration was associated with decreased compaction. Both the lowest (24.4% cTnT+) and highest (60.2% cTnT+) cardiomyocyte purities evaluated were associated with decreased compaction, whereas the greatest compaction was predicted to occur in constructs prepared with a 40–50% cTnT+ population. Constructs prepared with purified cardiomyocytes (≥75.5% cTnT+) compacted and formed syncytia well, although increased fibrin concentration in these groups was associated with decreased compaction, a reversal of the trend observed in unpurified cardiomyocytes. This study demonstrates an analytical approach to understanding cell–scaffold interactions in engineered tissues and provides a foundation for the development of more sophisticated and customized scaffold platforms for human cardiac tissue engineering.

3D printing for cardiovascular tissue engineering: a review

Although the current medical treatments have been successful in reducing the coronary heart disease related mortality rate, however there still exist various challenges in cardiac tissue engineering due to the hierarchical property of native myocardium and branched structure of blood vessels. The regeneration of progenitor cells, replacement infarcted cardiac tissues and the tissue-engineered constructs are the demand of the current era. In this contrast, 3D printing of scaffold for cardiac tissue engineering plays a crucial role. 3D printing techniques are used to generate patient-specific foundation that mimics the milieu of biological tissue. Various studies are under investigation to regenerate the cardiac tissues. Lack of regeneration capacity is a major hunt in cardiac tissue engineering. This review will provide an overview of 3D bioprinting techniques for cardiovascular tissue engineering. First, it summarises the background about bioprinting (working principles) followed by various bioink materials for cardiac tissue engineering. Recent approaches for the 3D printing of cardiac scaffolds for the regeneration of cardiac tissues are discussed.

Poly(3-hydroxyoctanoate), a promising new material for cardiac tissue engineering.

Cardiac tissue engineering (CTE) is currently a prime focus of research because of an enormous clinical need. In the present work, a novel functional material, poly(3-hydroxyoctanoate), P(3HO), a medium chain-length polyhydroxyalkanoate (PHA), produced using bacterial fermentation, was studied as a new potential material for CTE. Engineered constructs with improved mechanical properties, crucial for supporting the organ during new tissue regeneration, and enhanced surface topography, to allow efficient cell adhesion and proliferation, were fabricated. Results showed that the mechanical properties of the final patches were close to that of cardiac muscle. Biocompatibility of neat P(3HO) patches, assessed using neonatal ventricular rat myocytes (NVRM), showed that the polymer was as good as collagen in terms of cell viability, proliferation and adhesion. Enhanced cell adhesion and proliferation properties were observed when porous and fibrous structures were incorporated into the patches. In addition, no deleterious effect was observed on adult cardiomyocyte contraction when cardiomyocytes were seeded on the P(3HO) patches. Hence, P(3HO)-based multifunctional cardiac patches are promising constructs for efficient CTE. This work will have a positive impact on the development of P(3HO) and other PHAs as a novel new family of biodegradable functional materials with huge potential in a range of different biomedical applications, particularly CTE, leading to further interest and exploitation of these materials. Copyright © 2016 John Wiley & Sons, Ltd.

Surface Features of Recombinant Spider Silk Protein eADF4(κ16)‐Made Materials are Well‐Suited for Cardiac Tissue Engineering

Cardiovascular diseases causing high morbidity and mortality represent a major socioeconomic burden. The primary cause of impaired heart function is often the loss of cardiomyocytes. Thus, novel therapies aim at restoring the lost myocardial tissue. One promising approach is cardiac tissue engineering. Previously, it is shown that Antheraea mylitta silk protein fibroin is a suitable material for cardiac tissue engineering, however, its quality is difficult to control. To overcome this limitation, the interaction of primary rat heart cells with engineered Araneus diadematus fibroin 4 (κ16) (eADF4(κ16)) is investigated here, which is engineered based on the sequence of ADF4 by replacing the glutamic acid residue in the repetitive unit of its core domain with lysine. The data demonstrate that cardiomyocytes, fibroblasts, endothelial cells, and smooth muscle cells attach well to eADF4(κ16) films on glass coverslips which provide an engineered surface with a polycationic character. Moreover, eADF4(κ16) films have, in contrast to fibronectin films, no hypertrophic effect but allow the induction of cardiomyocyte hypertrophy. Finally, cardiomyocytes grown on eADF4(κ16) films respond to pro‐proliferative factors and exhibit proper cell‐to‐cell communication and electric coupling. Collectively, these data demonstrate that designed recombinant eADF4(κ16)‐based materials are promising materials for cardiac tissue engineering.

Regenerating Heart Using a Novel Compound and Human Wharton Jelly Mesenchymal Stem Cells

Myocardial infarction is a major problem in health system and most conventional therapy is not led to restoration of the health. Stem cell therapy is a method to regenerate the heart but today appropriate cell source and scaffold selection as extracellular matrix to achieve the best effect is disputing. In this study a combination of human Wharton jelly mesenchymal stem cells (HWJMSCs) with a novel compound consisting polyethylene glycol (PEG), hyaluronic acid and chitosan is presented to heart regeneration. After proliferation and expansion of HWJMSCs, these cells were mixed with scaffold and injected into the infarcted rabbit myocardium. After two months cardiac function and infarcted area were evaluated. Immunohistochemistry performed for vessel count and demonstrating of differentiation ability into cardiomyocytes. To confirm this ability PCR was done. Scanning electron microscope was used to evaluate angiogenesis. Improving cardiac function was higher in cell/scaffold group than the others and it was confirmed by SPECT results which showed least defect size in the myocardium. There were a lot of neoangiogenesis in the target group and also cardiomyogenesis observed in cell/scaffold group. PCR results confirmed the presence of differentiated cardiomyocytes and SEM showed well developed vessel in this group. Comparing macroscopic and microscopic results between all groups revealed that HWJMSC in combination with this scaffold led to brilliant results regarding cardiac function, angiogenesis and cardiogenesis. It is recommended using these cells and materials for cardiac tissue engineering and regeneration therapy.

On Materials for Cardiac Tissue Engineering.

In this essay the authors argue that chamber pressure dominates the biomechanics of the contraction cycle of the heart, while tissue stiffness dominates the relaxation cycle. This appears to be an under-recognized challenge in cardiac tissue engineering. Optimal approaches will involve constructing chambers or modulating the stiffness of the scaffold/substrate in synchrony with the beating cycle.

Electroactive polyurethane/siloxane derived from castor oil as a versatile cardiac patch, part II: HL-1 cytocompatibility and electrical characterizations.

In first part of this experiment, biocompatibility of the newly developed electroactive polyurethane/siloxane films containing aniline tetramer moieties was demonstrated with proliferation and differentiation of C2C12 myoblasts. Here we further assessed the cytocompatibility of the prepared samples with HL1-cell line, the electrophysiological properties and the patch clamp recording of the seeded cells over the selected electroactive sample. Presence of electroactive aniline tetramer in the structure of polyurethane/siloxane led to the increased expression of cardiac-specific genes of HL-1 cells involved in muscle contraction and electrical coupling. Our results showed that expression of Cx43, TrpT-2, and SERCA genes was significantly increased in conductive sample compared to tissue culture plate and the corresponding non-conductive analogous. The prepared materials were not only biocompatible in terms of cellular toxicity, but did not alter the intrinsic electrical characteristics of HL-1 cells. Embedding the electroactive moiety into the prepared films improved the properties of these polymeric cardiac construct through the enhanced transmission of electrical signals between the cells. Based on morphological observation, calcium imaging and electrophysiological recordings, we demonstrated the potential applicability of these materials for cardiac tissue engineering. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1398-1407, 2016.

Novel electrospun poly(glycerol sebacate)–zein fiber mats as candidate materials for cardiac tissue engineering

The application of a cardiac patch made of biodegradable polymer is a novel approach in regenerative therapies for infarcted cardiac tissue and aims to deliver healthy and functional cells on a mechanically supporting matrix to the damaged area of the myocardium. In this study a novel type of tissue engineered cardiac construct based on poly(glycerol sebacate) (PGS) blended with the corn protein zein was developed. Bead free electrospun PGS–zein fibers were fabricated using acetic acid as a benign solvent. In vitro degradation studies in PBS revealed a physicochemically stable system over a 28day period showing only a slight drop in pH after 28days. The results indicate that the novel PGS–zein fibrous structures are attractive biomaterials which can be valuable for cardiac patch applications thus warranting their further investigation in vitro and in vivo.

Poly(glycerol sebacate)\Poly(butylene succinate‐dilinoleate) Blends as Candidate Materials for Cardiac Tissue Engineering

SummaryPoly (glycerol sebacate) (PGS) and poly (butylene succinate‐dilinoleate) (PBS‐DLA) are biodegradable polymers with potential application in cardiac tissue engineering. In the present study novel blends comprising PGS prepolymer and PBS‐DLA were prepared with varying compositions (70/30, 60/40, 50/50, 40/60, 30/70 and 0/100 in weight percentage). The physical, chemical, and mechanical properties of the PGS/PBS‐DLA blends were measured and compared. By adding PBS‐DLA to PGS the need for curing PGS prepolymer was eliminated, as the blended films are chemically stable. With increasing amount of PBS‐DLA the hydrophobicity of the blend system increased reaching values close to that of neat PBS‐DLA films. Furthermore, addition of PBS‐DLA significantly affected the mechanical properties of the blends, i.e. the elastic modulus of the blends was enhanced with increasing PBS‐DLA addition from 1.2 MPa to 54 MPa. At the same time, PBS‐DLA addition led to decreased degradation rate of the films. Furthermore the PBS‐DLA counteracted the acidity of the free carboxylic groups on the free end chains of the PGS prepolymer. In vitro cytocompatibility studies indicated high biocompatibility. Taken together the results confirm that the novel PGS/PBS‐DLA matrices exhibit promising characteristics as a biomaterial for application in cardiac regeneration approaches.

A Mathematical Model for Analyzing the Elasticity, Viscosity, and Failure of Soft Tissue: Comparison of Native and Decellularized Porcine Cardiac Extracellular Matrix for Tissue Engineering

The clinical success of tissue-engineered constructs commonly requires mechanical properties that closely mimic those of the human tissue. Determining the viscoelastic properties of such biomaterials and the factors governing their failure profiles, however, has proven challenging, although collecting extensive data regarding their tensile behavior is straightforward. The easily calculated Young's modulus remains the most reported mechanical measure, regardless of its limitations, even though single-relaxation-time (SRT) models can provide much more information, which remain scarce due to a lack of manageable tools for implementing these models. We developed an easy-to-use algorithm for applying the Zener SRT model and determining the elastic moduli, viscosity, and failure profiles of materials under different mechanical tests in a user-independent manner. The algorithm was validated on the data resulting from tensile tests on native and decellularized porcine cardiac tissue, previously suggested as a promising scaffold material for cardiac tissue engineering. This analysis yields new and more accurate measurements such as the elastic moduli and viscosity, the model's relaxation time, and information on the factors governing the materials' failure profiles. These measurements indicate that the viscoelasticity and strength of the decellularized acellular extracellular matrix (ECM) are similar to those of native tissue, although its elasticity and apparent viscosity are higher. Nonetheless, reseeding and culturing the ECM with mesenchymal stem cells was shown to partially restore the mechanical properties lost after decellularization. We propose this algorithm as a platform for soft-tissue analysis that can provide comparable and unbiased measures for characterizing viscoelastic biomaterials commonly used in tissue engineering.

The functional properties of nephronectin: An adhesion molecule for cardiac tissue engineering

Despite significant advances in preventive cardiovascular medicine and therapy for acute and chronic heart failure, cardiovascular diseases remain among the leading causes of death worldwide. In recent years cardiac tissue engineering has been established as a possible future treatment option for cardiac disease. However, the quality of engineered myocardial tissues remains poor. In tissue engineering it is important that the scaffold allows cells to attach, spread, maintain their differentiation status or differentiate into functional cells in order to exhibit their physiological function. Here, we have investigated the suitability of the natural cardiac extracellular matrix component nephronectin as an adhesive material for cardiac tissue engineering. Primary neonatal rat cardiomyocytes were seeded on collagen-, fibronectin- or nephronectin-coated glass coverslips and analyzed for cell adhesion, cellular metabolic activity, response to extracellular stimuli, cell-to-cell communication, differentiation and contractility. Our data demonstrate that most neonatal cardiomyocytes attached in an RGD domain-dependent manner within 18 h to nephronectin. The cells exhibited high metabolic activity, responded to growth factor stimuli and maintained their differentiation status. Moreover, nephronectin promoted sarcomere maturation and alignment, cell-to-cell communication and synchronous contractions. In conclusion, our findings demonstrate that nephronectin has excellent properties for cardiomyocyte adhesion and function and thus has the potential to improve current cardiac tissue engineering approaches.

In vitro construction of tissue-engineered cardiac tissue sheet by small intestinal submucosa with bone mesenchymal stem cells

Objective To explore the feasibility of in vitro construction of tissue-engineered cardiac sheet by small intestinal submucosa(SIS) with bone mesenchymal stem cells(BMSCs). Methods BMSCs separated from rat bone marrow were induced by 5-azacytidine(5-Aza) for 3 weeks,and were seeded on the serosal side of acellular SIS scaffold.The tissue-engineered cardiac tissue sheet was established in vitro after co-culture in dynamic culture system for 2 weeks,and its properties were evaluated by histological,ultrastructural and immunohistochemical examinations. Results After co-culture for 2 weeks,HE staining revealed that the seeded cells were not restricted in the upper area of SIS,forming multiple uniform layers on SIS,and some cells penetrated and migrated into the porous matrix.Scanning electronic microscopy revealed that BMSCs adhered,proliferated and migrated well on SIS,and secreted a large amount of extracellular matrix.Immunohistochemical staining demonstrated that the cells on SIS were cardiomyocyte-like cells with the expression of α-actin,cTnⅠ and connexin-43. Conclusion The engineered cardiac tissue sheet has been successfully constructed by SIS with 5-Aza-induced BMSCs in vitro,and SIS is an ideal bio-scaffold material for cardiac tissue engineering.