3D models of dilated cardiomyopathy: Shaping the chemical, physical and topographical properties of biomaterials to mimic the cardiac extracellular matrix

Advancing 3D Engineered In Vitro Models for Heart Failure Research: Key Features and Considerations

Heart failure is characterized by intricate myocardial remodeling that impairs the heart's pumping and/or relaxation capacity, ultimately reducing cardiac output. It represents a major public health burden, given its high prevalence and associated morbidity and mortality rates, which continue to challenge healthcare systems worldwide. Despite advancements in medical science, there are no treatments that address the disease at its core. The development of three-dimensional engineered in vitro models that closely mimic the (patho)physiology and drug responses of the myocardium has the potential to revolutionize our insights and uncover new therapeutic avenues. Key aspects of these models include the precise replication of the extracellular matrix structure, cell composition, micro-architecture, mechanical and electrical properties, and relevant physiological and pathological stimuli, such as fluid flow, mechanical load, electrical signal propagation, and biochemical cues. Additionally, to fully capture heart failure and its diversity in vivo, it is crucial to consider factors such as age, gender, interactions with other organ systems and external influences-thereby recapitulating unique patient and disease phenotypes. This review details these model features and their significance in heart failure research, with the aim of enhancing future platforms that will deepen our understanding of the disease and facilitate the development of novel, effective therapies.

Versatile effects of galectin-1 protein-containing lipid bilayer coating for cardiovascular applications

Modulating inflammatory cells in an implantation site leads to severe complications and still unsolved challenges for blood-contacting medical devices. Inspired by the role of galectin-1 (Gal-1) in selective functions on multiple cells and immunomodulatory processes, we prepared a biologically target-specific surface coated with the lipid bilayer containing Gal-1 (Gal-1-SLB) and investigate the proof of the biological effects. First, lipoamido-dPEG-acid was deposited on a gold-coated substrate to form a self-assembled monolayer and then conjugated dioleoylphosphatidylethanolamine (DOPE) onto that to produce a lower leaflet of the supported lipid bilayer (SLB) before fusing membrane-derived vesicles extracted from B16-F10 cells. The Gal-1-SLB showed the expected anti-fouling activity by revealing the resistance to protein adsorption and bacterial adhesion. In vitro studies showed that the Gal-1-SLB can promote endothelial function and inhibit smooth muscle cell proliferation. Moreover, Gal-1- SLB presents potential function for endothelial cell migration and angiogenic activities. In vitro macrophage culture studies showed that the Gal-1-SLB attenuated the LPS-induced inflammation and the production of macrophage-secreted inflammatory cytokines. Finally, the implanted Gal-1-SLB reduced the infiltration of immune cells at the tissue-implant interface and increased markers for M2 polarization and blood vessel formation in vivo. This straightforward surface coating with Gal-1 can be a useful strategy for modulating the vascular and immune cells around a blood-contacting device.

Three-Dimensional iPSC-Based In Vitro Cardiac Models for Biomedical and Pharmaceutical Research Applications

Cardiovascular diseases are a major cause of death worldwide. Advanced in vitro models can be the key stone for a better understanding of the mechanisms at the basis of the different pathologies, supporting the development of novel therapeutic protocols. In particular, the implementation of induced pluripotent stem cell (iPSC) technology allows for the generation of a patient-specific pluripotent cell line that is able to differentiate in several organ-specific cell subsets while retaining the patient genetic background, thus putting the basis for personalized in vitro modeling toward personalized medicine. The design of iPSC-based models able to recapitulate the complexity of the cardiac environment is a critical goal. Here, we review some of the published efforts to exploit three dimensional (3D) iPSC-based methods to recapitulate the relevant cardiomyopathies, including genetically and non-genetically determined cardiomyopathies and cardiotoxicity studies. Finally, we discuss the actual method limitations and the future perspectives in the field.

Development of Mesoporous Silica Nanoparticle-Based Films with Tunable Arginine-Glycine-Aspartate Peptide Global Density and Clustering Levels to Study Stem Cell Adhesion and Differentiation

Stem cell adhesion is mediated via the binding of integrin receptors to adhesion motifs present in the extracellular matrix (ECM). The spatial organization of adhesion ligands plays an important role in stem cell integrin-mediated adhesion. In this study, we developed a series of biointerfaces using arginine-glycine-aspartate (RGD)-functionalized mesoporous silica nanoparticles (MSN-RGD) to study the effect of RGD adhesion ligand global density (ligand coverage over the surface), spacing, and RGD clustering levels on stem cell adhesion and differentiation. To prepare the biointerface, MSNs were chemically functionalized with RGD peptides via an antifouling poly(ethylene glycol) (PEG) linker. The RGD surface functionalization ratio could be controlled to create MSNs with high and low RGD ligand clustering levels. MSN films with varying RGD global densities could be created by blending different ratios of MSN-RGD and non-RGD-functionalized MSNs together. A computational simulation study was performed to analyze nanoparticle distribution and RGD spacing on the resulting surfaces to determine experimental conditions. Enhanced cell adhesion and spreading were observed when RGD global density increased from 1.06 to 5.32 nmol cm-2 using highly clustered RGD-MSN-based films. Higher RGD ligand clustering levels led to larger cell spreading and increased formation of focal adhesions. Moreover, a higher RGD ligand clustering level promoted the expression of alkaline phosphatase in hMSCs. Overall, these findings indicate that both RGD global density and clustering levels are crucial variables in regulating stem cell behaviors. This study provides important information about ligand-integrin interactions, which could be implemented into biomaterial design to achieve optimal performance of adhesive functional peptides.

Fabrication of bio-inspired anisotropic structures from biopolymers for biomedical applications: A review

The anisotropic features play indispensable roles in regulating various life activities in different organisms. Increasing efforts have been made to learn and mimic various tissues' intrinsic anisotropic structure or functionality for broad applications in different areas, especially in biomedicine and pharmacy. This paper discusses the strategies for fabricating biomaterials using biopolymers for biomedical applications with the case study analysis. Biopolymers, including different polysaccharides, proteins, and their derivates, that have been confirmed with sound biocompatibility for different biomedical applications are summarized, with a special focus on nanocellulose. Advanced analytical techniques for understanding and characterizing the biopolymer-based anisotropic structures for various biomedical applications are also summarized. Challenges still exist in precisely constructing biopolymers-based biomaterials with anisotropic structures from molecular to macroscopic levels and fitting the dynamic processes in native tissue. It is foreseeable that with the advancement of biopolymers' molecular functionalization, biopolymer building block orientation manipulation strategies, and structural characterization techniques, developing anisotropic biopolymer-based biomaterials for different biomedical applications would significantly contribute to a friendly disease-curing and healthcare experience.

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.

Anisotropic dense collagen hydrogels with two ranges of porosity to mimic the skeletal muscle extracellular matrix

Despite the crucial role of the extracellular matrix (ECM) in the organotypic organization and function of skeletal muscles, most 3D models do not mimic its specific characteristics, namely its biochemical composition, stiffness, anisotropy, and porosity. Here, a novel 3D in vitro model of muscle ECM was developed reproducing these four crucial characteristics of the native ECM. An anisotropic hydrogel mimicking the muscle fascia was obtained thanks to unidirectional 3D printing of dense collagen with aligned collagen fibrils. The space between the different layers was tuned to generate an intrinsic network of pores (100 μm) suitable for nutrient and oxygen diffusion. By modulating the gelling conditions, the mechanical properties of the construct reached those measured in the physiological muscle ECM. This artificial matrix was thus evaluated for myoblast differentiation. The addition of large channels (600 μm) by molding permitted to create a second range of porosity suitable for cell colonization without altering the physical properties of the hydrogel. Skeletal myoblasts embedded in Matrigel®, seeded within the channels, organized in 3D, and differentiated into multinucleated myotubes. These results show that porous and anisotropic dense collagen hydrogels are promising biomaterials to model skeletal muscle ECM.

Cyto- and bio-compatibility assessment of plasma-treated polyvinylidene fluoride scaffolds for cardiac tissue engineering

As part of applications dealing with cardiovascular tissue engineering, drop-cast polyvinylidene fluoride (PVDF) scaffolds have been treated by cold plasma to enhance their adherence to cardiac cells. The scaffolds were treated in a dielectric barrier device where cold plasma was generated in a gaseous environment combining a carrier gas (helium or argon) with/without a reactive gas (molecular nitrogen). We show that an Ar-N₂ plasma treatment of 10 min results in significant hydrophilization of the scaffolds, with contact angles as low as 52.4° instead of 132.2° for native PVDF scaffolds. Correlation between optical emission spectroscopy and X-ray photoelectron spectroscopy shows that OH radicals from the plasma phase can functionalize the surface scaffolds, resulting in improved wettability. For all plasma-treated PVDF scaffolds, the adhesion and maturation of primary cardiomyocytes is increased, showing a well-organized sarcomeric structure (α-actinin immunostaining). The efficacy of plasma treatment was also supported by real-time PCR analysis to demonstrate an increased expression of the genes related to adhesion and cardiomyocyte function. Finally, the biocompatibility of the PVDF scaffolds was studied in a cardiac environment, after implantation of acellular scaffolds on the surface of the heart of healthy mice. Seven and 28 days after implantation, no exuberant fibrosis and no multinucleated giant cells were visible in the grafted area, hence demonstrating the absence of foreign body reaction and the biocompatibility of these scaffolds.

Cardiac tissue engineering: Multiple approaches and potential applications

The overall increase in cardiovascular diseases and, specifically, the ever-rising exposure to cardiotoxic compounds has greatly increased in vivo animal testing; however, mainly due to ethical concerns related to experimental animal models, there is a strong interest in new in vitro models focused on the human heart. In recent years, human pluripotent stem cells-derived cardiomyocytes (hiPSC-CMs) emerged as reference cell systems for cardiac studies due to their biological similarity to primary CMs, the flexibility in cell culture protocols, and the capability to be amplified several times. Furthermore, the ability to be genetically reprogrammed makes patient-derived hiPSCs, a source for studies on personalized medicine. In this mini-review, the different models used for in vitro cardiac studies will be described, and their pros and cons analyzed to help researchers choose the best fitting model for their studies. Particular attention will be paid to hiPSC-CMs and three-dimensional (3D) systems since they can mimic the cytoarchitecture of the human heart, reproducing its morphological, biochemical, and mechanical features. The advantages of 3D in vitro heart models compared to traditional 2D cell cultures will be discussed, and the differences between scaffold-free and scaffold-based systems will also be spotlighted.

Artificial Scaffolds in Cardiac Tissue Engineering

Cardiovascular diseases are a leading cause of death worldwide. Current treatments directed at heart repair have several disadvantages, such as a lack of donors for heart transplantation or non-bioactive inert materials for replacing damaged tissue. Because of the natural lack of regeneration of cardiomyocytes, new treatment strategies involve stimulating heart tissue regeneration. The basic three elements of cardiac tissue engineering (cells, growth factors, and scaffolds) are described in this review, with a highlight on the role of artificial scaffolds. Scaffolds for cardiac tissue engineering are tridimensional porous structures that imitate the extracellular heart matrix, with the ability to promote cell adhesion, migration, differentiation, and proliferation. In the heart, there is an important requirement to provide scaffold cellular attachment, but scaffolds also need to permit mechanical contractility and electrical conductivity. For researchers working in cardiac tissue engineering, there is an important need to choose an adequate artificial scaffold biofabrication technique, as well as the ideal biocompatible biodegradable biomaterial for scaffold construction. Finally, there are many suitable options for researchers to obtain scaffolds that promote cell-electrical interactions and tissue repair, reaching the goal of cardiac tissue engineering.

Generation of an Adequate Perfusion Network within Dense Collagen Hydrogels Using Thermoplastic Polymers as Sacrificial Matrix to Promote Cell Viability

Dense collagen hydrogels are promising biomaterials for several tissue-engineering applications. They exhibit high mechanical properties, similar to physiological extracellular matrices, and do not shrink under cellular activity. However, they suffer from several drawbacks, such as weak nutrient and O₂ diffusion, impacting cell survival. Here, we report a novel strategy to create a perfusion system within dense and thick collagen hydrogels to promote cell viability. The 3D printing of a thermoplastic filament (high-impact polystyrene, HIPS) with a three-wave shape is used to produce an appropriate sacrificial matrix. The HIPS thermoplastic polymer allows for good shape fidelity of the filament and does not collapse under the mechanical load of the collagen solution. After the collagen gels around the filament and dissolves, a channel is generated, allowing for adequate and rapid hydrogel perfusion. The dissolution process does not alter the collagen hydrogel’s physical or chemical properties, and the perfusion is associated with an increased fibroblast survival. Here, we report the novel utilization of thermoplastics to generate a perfusion network within biomimetic collagen hydrogels.

Human Induced Pluripotent Stem Cell as a Disease Modeling and Drug Development Platform-A Cardiac Perspective

A comprehensive understanding of the pathophysiology and cellular responses to drugs in human heart disease is limited by species differences between humans and experimental animals. In addition, isolation of human cardiomyocytes (CMs) is complicated because cells obtained by biopsy do not proliferate to provide sufficient numbers of cells for preclinical studies in vitro. Interestingly, the discovery of human-induced pluripotent stem cell (hiPSC) has opened up the possibility of generating and studying heart disease in a culture dish. The combination of reprogramming and genome editing technologies to generate a broad spectrum of human heart diseases in vitro offers a great opportunity to elucidate gene function and mechanisms. However, to exploit the potential applications of hiPSC-derived-CMs for drug testing and studying adult-onset cardiac disease, a full functional characterization of maturation and metabolic traits is required. In this review, we focus on methods to reprogram somatic cells into hiPSC and the solutions for overcome immaturity of the hiPSC-derived-CMs to mimic the structure and physiological properties of the adult human CMs to accurately model disease and test drug safety. Finally, we discuss how to improve the culture, differentiation, and purification of CMs to obtain sufficient numbers of desired types of hiPSC-derived-CMs for disease modeling and drug development platform.

Coaxial Electrospun PLLA Fibers Modified with Water-Soluble Materials for Oligodendrocyte Myelination

Myelin sheaths are essential in maintaining the integrity of axons. Development of the platform for in vitro myelination would be especially useful for demyelinating disease modeling and drug screening. In this study, a fiber scaffold with a core-shell structure was prepared in one step by the coaxial electrospinning method. A high-molecular-weight polymer poly-L-lactic acid (PLLA) was used as the core, while the shell was a natural polymer material such as hyaluronic acid (HA), sodium alginate (SA), or chitosan (CS). The morphology, differential scanning calorimetry (DSC), Fourier transform infrared spectra (FTIR), contact angle, viability assay, and in vitro myelination by oligodendrocytes were characterized. The results showed that such fibers are bead-free and continuous, with an average size from 294 ± 53 to 390 ± 54 nm. The DSC and FTIR curves indicated no changes in the phase state of coaxial brackets. Hyaluronic acid/PLLA coaxial fibers had the minimum contact angle (53.1° ± 0.24°). Myelin sheaths were wrapped around a coaxial electrospun scaffold modified with water-soluble materials after a 14-day incubation. All results suggest that such a scaffold prepared by coaxial electrospinning potentially provides a novel platform for oligodendrocyte myelination.