Bioengineering approaches to treat the failing heart: from cell biology to 3D printing

Multimaterial Printing of Serpentine Microarchitectures with Synergistic Mechanical/Piezoelectric Stimulation for Enhanced Cardiac-Specific Functional Regeneration

Recreating the natural heart's mechanical and electrical environment is crucial for engineering functional cardiac tissue and repairing infarcted myocardium in vivo. In this study, multimaterial-printed serpentine microarchitectures are presented with synergistic mechanical/piezoelectric stimulation, incorporating polycaprolactone (PCL) microfibers for mechanical support, polyvinylidene fluoride (PVDF) microfibers for piezoelectric stimulation, and magnetic PCL/Fe3O4 for controlled deformation via an external magnet. Rat cardiomyocytes in piezoelectric constructs, subjected to dynamic mechanical stimulation, exhibit advanced maturation, featuring superior sarcomeric structures, improved calcium transients, and upregulated maturation genes compared to non-piezoelectric constructs. Furthermore, these engineered piezoelectric cardiac constructs demonstrate significant structural and functional repair of infarcted myocardium, as evidenced by enhanced ejection and shortening fraction, reduced fibrosis and inflammation, and increased angiogenesis. The findings underscore the therapeutic potential of piezoelectric cardiac constructs for myocardial infarction therapy.

Chemically Programmed Hydrogels for Spatiotemporal Modulation of the Cardiac Pathological Microenvironment

After myocardial infarction (MI), sustained ischemic events induce pathological microenvironments characterized by ischemia-hypoxia, oxidative stress, inflammatory responses, matrix remodeling, and fibrous scarring. Conventional clinical therapies lack spatially targeted and temporally responsive modulation of the infarct microenvironment, leading to limited myocardial repair. Engineered hydrogels have a chemically programmed toolbox for minimally invasive localization of the pathological microenvironment and personalized responsive modulation over different pathological periods. Chemically programmed strategies for crosslinking interactions, interfacial binding, and topological microstructures in hydrogels enable minimally invasive implantation and in situ integration tailored to the myocardium. This enhances substance exchange and signal interactions within the infarcted microenvironment. Programmed responsive polymer networks, intelligent micro/nanoplatforms, and biological therapeutic cues contribute to the formation of microenvironment-modulated hydrogels with precise targeting, spatiotemporal control, and on-demand feedback. Therefore, this review summarizes the features of the MI microenvironment and chemically programmed schemes for hydrogels to conform, integrate, and modulate the cardiac pathological microenvironment. Chemically programmed strategies for oxygen-generating, antioxidant, anti-inflammatory, provascular, and electrointegrated hydrogels to stimulate iterative and translational cardiac tissue engineering are discussed.

Engineered heart tissue: Design considerations and the state of the art

Originally developed more than 20 years ago, engineered heart tissue (EHT) has become an important tool in cardiovascular research for applications such as disease modeling and drug screening. Innovations in biomaterials, stem cell biology, and bioengineering, among other fields, have enabled EHT technologies to recapitulate many aspects of cardiac physiology and pathophysiology. While initial EHT designs were inspired by the isolated-trabecula culture system, current designs encompass a variety of formats, each of which have unique strengths and limitations. In this review, we describe the most common EHT formats, and then systematically evaluate each aspect of their design, emphasizing the rational selection of components for each application.

Chronological-Programmed Black Phosphorus Hydrogel for Responsive Modulation of the Pathological Microenvironment in Myocardial Infarction

Electroactive hydrogels have garnered extensive interest as a promising approach to myocardial tissue engineering. However, the challenges of spatiotemporal-specific modulation of individual pathological processes and achieving nontoxic bioresorption still remain. Herein, inspired by the entire postinfarct pathological processes, an injectable conductive bioresorbable black phosphorus nanosheets (BPNSs)-loaded hydrogel (BHGD) was developed via reactive oxide species (ROS)-sensitive disulfide-bridge and photomediated cross-linking reaction. Significantly, the chronologically programmed BHGD hydrogel can achieve graded modulation during the inflammatory, proliferative, and maturation phases of myocardial infarction (MI). More details, during early infarction, the BHGD hydrogel can effectively reduce ROS levels in the MI area, inhibit cellular oxidative stress damage, and promote macrophage M2 polarization, creating a favorable environment for damaged myocardium repair. Meanwhile, the ROS-responsive structure can protect BPNSs from degradation and maintain good conductivity under MI microenvironments. Therefore, the BHGD hydrogel possesses tissue-matched modulus and conductivity in the MI area, facilitating cardiomyocyte maturation and electrical signal exchange, compensating for impaired electrical signaling, and promoting vascularization in infarcted areas in the maturation phase. More importantly, all components of the hydrogel degrade into nontoxic substances without adverse effects on vital organs. Overall, the presented BPNS-loaded hydrogel offers an expandable and safe option for clinical treatment of MI.

Development of 3D printed electrospun vascular graft loaded with tetramethylpyrazine for reducing thrombosis and restraining aneurysmal dilatation

Background

Small-diameter vascular grafts have become the focus of attention in tissue engineering. Thrombosis and aneurysmal dilatation are the two major complications of the loss of vascular access after surgery. Therefore, we focused on fabricating 3D printed electrospun vascular grafts loaded with tetramethylpyrazine (TMP) to overcome these limitations.

Methods

Based on electrospinning and 3D printing, 3D-printed electrospun vascular grafts loaded with TMP were fabricated. The inner layer of the graft was composed of electrospun poly(L-lactic-co-caprolactone) (PLCL) nanofibers and the outer layer consisted of 3D printed polycaprolactone (PCL) microfibers. The characterization and mechanical properties were tested. The blood compatibility and in vitro cytocompatibility of the grafts were also evaluated. Additionally, rat abdominal aortas were replaced with these 3D-printed electrospun grafts to evaluate their biosafety.

Results

Mechanical tests demonstrated that the addition of PCL microfibers could improve the mechanical properties. In vitro experimental data proved that the introduction of TMP effectively inhibited platelet adhesion. Afterwards, rat abdominal aorta was replaced with 3D-printed electrospun grafts. The 3D-printed electrospun graft loaded with TMP showed good biocompatibility and mechanical strength within 6 months and maintained substantial patency without the occurrence of acute thrombosis. Moreover, no obvious aneurysmal dilatation was observed.

Conclusions

The study demonstrated that 3D-printed electrospun vascular grafts loaded with TMP may have the potential for injured vascular healing.

Canonical Wnt signaling directs the generation of functional human PSC-derived atrioventricular canal cardiomyocytes in bioprinted cardiac tissues

The creation of a functional 3D bioprinted human heart remains challenging, largely due to the lack of some crucial cardiac cell types, including the atrioventricular canal (AVC) cardiomyocytes, which are essential to slow down the electrical impulse between the atrium and ventricle. By utilizing single-cell RNA sequencing analysis and a 3D bioprinting technology, we discover that stage-specific activation of canonical Wnt signaling creates functional AVC cardiomyocytes derived from human pluripotent stem cells. These cardiomyocytes display morphological characteristics and express molecular markers of AVC cardiomyocytes, including transcription factors TBX2 and MSX2. When bioprinted in prefabricated cardiac tissues, these cardiomyocytes successfully delay the electrical impulse, demonstrating their capability of functioning as the AVC cardiomyocytes in vitro. Thus, these findings not only identify canonical Wnt signaling as a key regulator of the AVC cardiomyocyte differentiation in vitro, but, more importantly, provide a critical cellular source for the biofabrication of a functional human heart.

Ceria-Based Therapeutic Antioxidants for Biomedical Applications

The growing interest in nanomedicine over the last 20 years has carved out a research field called "nanocatalytic therapy," where catalytic reactions mediated by nanomaterials are employed to intervene in disease-critical biomolecular processes. Among many kinds of catalytic/enzyme-mimetic nanomaterials investigated thus far, ceria nanoparticles stand out from others owing to their unique scavenging properties against biologically noxious free radicals, including reactive oxygen species (ROS) and reactive nitrogen species (RNS), by exerting enzyme mimicry and nonenzymatic activities. Much effort has been made to utilize ceria nanoparticles as self-regenerating antioxidative and anti-inflammatory agents for various kinds of diseases, given the detrimental effects of ROS and RNS therein that need alleviation. In this context, this review is intended to provide an overview as to what makes ceria nanoparticles merit attention in disease therapy. The introductory part describes the characteristics of ceria nanoparticles as an oxygen-deficient metal oxide. The pathophysiological roles of ROS and RNS are then presented, as well as their scavenging mechanisms by ceria nanoparticles. Representative examples of recent ceria-nanoparticle-based therapeutics are summarized by categorization into organ and disease types, followed by the discussion on the remaining challenges and future research directions.

Heart-on-a-chip systems with tissue-specific functionalities for physiological, pathological, and pharmacological studies

Recent advances in heart-on-a-chip systems hold great promise to facilitate cardiac physiological, pathological, and pharmacological studies. This review focuses on the development of heart-on-a-chip systems with tissue-specific functionalities. For one thing, the strategies for developing cardiac microtissues on heart-on-a-chip systems that closely mimic the structures and behaviors of the native heart are analyzed, including the imitation of cardiac structural and functional characteristics. For another, the development of techniques for real-time monitoring of biophysical and biochemical signals from cardiac microtissues on heart-on-a-chip systems is introduced, incorporating cardiac electrophysiological signals, contractile activity, and biomarkers. Furthermore, the applications of heart-on-a-chip systems in intelligent cardiac studies are discussed regarding physiological/pathological research and pharmacological assessment. Finally, the future development of heart-on-a-chip toward a higher level of systematization, integration, and maturation is proposed.

Construction of millimeter-scale vascularized engineered myocardial tissue using a mixed gel

Engineering myocardium has shown great clinal potential for repairing permanent myocardial injury. However, the lack of perfusing blood vessels and difficulties in preparing a thick-engineered myocardium result in its limited clinical use. We prepared a mixed gel containing fibrin (5 mg/ml) and collagen I (0.2 mg/ml) and verified that human umbilical vein endothelial cells (HUVECs) and human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) could form microvascular lumens and myocardial cell clusters by harnessing the low-hardness and hyperelastic characteristics of fibrin. hiPSC-CMs and HUVECs in the mixed gel formed self-organized cell clusters, which were then cultured in different media using a three-phase approach. The successfully constructed vascularized engineered myocardial tissue had a spherical structure and final diameter of 1-2 mm. The tissue exhibited autonomous beats that occurred at a frequency similar to a normal human heart rate. The internal microvascular lumen could be maintained for 6 weeks and showed good results during preliminary surface re-vascularization in vitro and vascular remodeling in vivo. In summary, we propose a simple method for constructing vascularized engineered myocardial tissue, through phased cultivation that does not rely on high-end manufacturing equipment and cutting-edge preparation techniques. The constructed tissue has potential value for clinical use after preliminary evaluation.

3D Printing of Collagen Scaffold with Enhanced Resolution in a Citrate-Modulated Gellan Gum Microgel Bath

3D printing in a microgel-based supporting bath enables the construction of complex structures with soft and watery biomaterials but the low print resolution is usually an obstacle to its practical application in tissue engineering. Herein, high-resolution printing of a 3D collagen organ scaffold is realized by using an engineered Gellan gum (GG) microgel bath containing trisodium citrate (TSC). The introduction of TSC into the bath system not only mitigates the aggregation of GG microgels, leading to a more homogeneous bath morphology but also suppresses the diffusion of the collagen ink in the bath due to the dehydration effect of TSC, both of which contribute to the improvement of print resolution. 3D collagen organ structures such as hand, ear, and heart are successfully constructed with high shape fidelity in the developed bath. After printing, the GG and TSC can be easily removed by washing with water, and the obtained collagen product exhibits good cell affinity in a tissue scaffold application. This work offers an easy-to-operate strategy for developing a microgel bath for high-resolution printing of collagen, providing an alternative path to in vitro 3D organ construction.

Modified ECM-Based Bioink for 3D Printing of Multi-Scale Vascular Networks

The survival and function of tissues depend on appropriate vascularization. Blood vessels of the tissues supply oxygen, and nutrients and remove waste and byproducts. Incorporating blood vessels into engineered tissues is essential for overcoming diffusion limitations, improving tissue function, and thus facilitating the fabrication of thick tissues. Here, we present a modified ECM bioink, with enhanced mechanical properties and endothelial cell-specific adhesion motifs, to serve as a building material for 3D printing of a multiscale blood vessel network. The bioink is composed of natural ECM and alginate conjugated with a laminin adhesion molecule motif (YIGSR). The hybrid hydrogel was characterized for its mechanical properties, biochemical content, and ability to interact with endothelial cells. The pristine and modified hydrogels were mixed with induced pluripotent stem cells derived endothelial cells (iPSCs-ECs) and used to print large blood vessels with capillary beds in between.

Multimaterial 3D and 4D Bioprinting of Heterogenous Constructs for Tissue Engineering

Additive manufacturing (AM), which is based on the principle of layer-by-layer shaping and stacking of discrete materials, has shown significant benefits in the fabrication of complicated implants for tissue engineering (TE). However, many native tissues exhibit anisotropic heterogenous constructs with diverse components and functions. Consequently, the replication of complicated biomimetic constructs using conventional AM processes based on a single material is challenging. Multimaterial 3D and 4D bioprinting (with time as the fourth dimension) has emerged as a promising solution for constructing multifunctional implants with heterogenous constructs that can mimic the host microenvironment better than single-material alternatives. Notably, 4D-printed multimaterial implants with biomimetic heterogenous architectures can provide a time-dependent programmable dynamic microenvironment that can promote cell activity and tissue regeneration in response to external stimuli. This paper first presents the typical design strategies of biomimetic heterogenous constructs in TE applications. Subsequently, the latest processes in the multimaterial 3D and 4D bioprinting of heterogenous tissue constructs are discussed, along with their advantages and challenges. In particular, the potential of multimaterial 4D bioprinting of smart multifunctional tissue constructs is highlighted. Furthermore, this review provides insights into how multimaterial 3D and 4D bioprinting can facilitate the realization of next-generation TE applications.

Characterization of Bioinks Prepared via Gelifying Extracellular Matrix from Decellularized Porcine Myocardia

Since the emergence of 3D bioprinting technology, both synthetic and natural materials have been used to develop bioinks for producing cell-laden cardiac grafts. To this end, extracellular-matrix (ECM)-derived hydrogels can be used to develop scaffolds that closely mimic the complex 3D environments for cell culture. This study presents a novel cardiac bioink based on hydrogels exclusively derived from decellularized porcine myocardium loaded with human-bone-marrow-derived mesenchymal stromal cells. Hence, the hydrogel can be used to develop cell-laden cardiac patches without the need to add other biomaterials or use additional crosslinkers. The scaffold ultrastructure and mechanical properties of the bioink were characterized to optimize its production, specifically focusing on the matrix enzymatic digestion time. The cells were cultured in 3D within the developed hydrogels to assess their response. The results indicate that the hydrogels fostered inter-cell and cell-matrix crosstalk after 1 week of culture. In conclusion, the bioink developed and presented in this study holds great potential for developing cell-laden customized patches for cardiac repair.

Cardiac regeneration - Past advancements, current challenges, and future directions

Cardiovascular disease is the leading cause of mortality and morbidity worldwide. Despite improvements in the standard of care for patients with heart diseases, including innovation in pharmacotherapy and surgical interventions, none have yet been proven effective to prevent the progression to heart failure. Cardiac transplantation is the last resort for patients with severe heart failure, but donor shortages remain a roadblock. Cardiac regenerative strategies include cell-based therapeutics, gene therapy, direct reprogramming of non-cardiac cells, acellular biologics, and tissue engineering methods to restore damaged hearts. Significant advancements have been made over the past several decades within each of these fields. This review focuses on the advancements of: 1) cell-based cardiac regenerative therapies, 2) the use of noncoding RNA to induce endogenous cell proliferation, and 3) application of bioengineering methods to promote retention and integration of engrafted cells. Different cell sources have been investigated, including adult stem cells derived from bone marrow and adipose cells, cardiosphere-derived cells, skeletal myoblasts, and pluripotent stem cells. In addition to cell-based transplantation approaches, there have been accumulating interest over the past decade in inducing endogenous CM proliferation for heart regeneration, particularly with the use of noncoding RNAs such as miRNAs and lncRNAs. Bioengineering applications have focused on combining cell-transplantation approaches with fabrication of a porous, vascularized scaffold using biomaterials and advanced bio-fabrication techniques that may offer enhanced retention of transplanted cells, with the hope that these cells would better engraft with host tissue to improve cardiac function. This review summarizes the present status and future challenges of cardiac regenerative therapies.

Micropatterned fibrin scaffolds increase cardiomyocyte alignment and contractility for the fabrication of engineered myocardial tissue

Cardiovascular disease is the leading cause of death in the United States, which can result in blockage of a coronary artery, triggering a myocardial infarction (MI), scar tissue formation in the myocardium, and ultimately heart failure. Currently, the gold-standard solution for total heart failure is a heart transplantation. An alternative to total-organ transplantation is surgically remodeling the ventricle with the implantation of a cardiac patch. Acellular cardiac patches have previously been investigated using synthetic or decellularized native materials to improve cardiac function. However, a limitation of this strategy is that acellular cardiac patches only reshape the ventricle and do not increase cardiac contractile function. Toward the development of a cardiac patch, our laboratory previously developed a cell-populated composite fibrin scaffold and aligned microthreads to recapitulate the mechanical properties of native myocardium. In this study, we explore micropatterning the surfaces of fibrin gels to mimic anisotropic native tissue architecture and promote cellular alignment of human induced pluripotent stem cell cardiomyocytes (hiPS-CM), which is crucial for increasing scaffold contractile properties. hiPS-CMs seeded on micropatterned surfaces exhibit cellular elongation, distinct sarcomere alignment, and circumferential connexin-43 staining at 14 days of culture, which are necessary for mature contractile properties. Constructs were also subject to electrical stimulation during culture to promote increased contractile properties. After 7 days of stimulation, contractile strains of micropatterned constructs were significantly higher than unpatterned controls. These results suggest that the use of micropatterned topographic cues on fibrin scaffolds may be a promising strategy for creating engineered cardiac tissue.

A Platform for Assessing Cellular Contractile Function Based on Magnetic Manipulation of Magnetoresponsive Hydrogel Films

Despite significant advancements in in vitro cardiac modeling approaches, researchers still lack the capacity to obtain in vitro measurements of a key indicator of cardiac function: contractility, or stroke volume under specific loading conditions-defined as the pressures to which the heart is subjected prior to and during contraction. This work puts forward a platform that creates this capability, by providing a means of dynamically controlling loading conditions in vitro. This dynamic tissue loading platform consists of a thin magnetoresponsive hydrogel cantilever on which 2D engineered myocardial tissue is cultured. Exposing the cantilever to an external magnetic field-generated by positioning magnets at a controlled distance from the cantilever-causes the hydrogel film to stretch, creating tissue load. Next, cell contraction is induced through electrical stimulation, and the force of the contraction is recorded, by measuring the cantilever's deflection. Force-length-based measurements of contractility are then derived, comparable to clinical measurements. In an illustrative application, the platform is used to measure contractility both in untreated myocardial tissue and in tissue exposed to an inotropic agent. Clear differences are observed between conditions, suggesting that the proposed platform has significant potential to provide clinically relevant measurements of contractility.

Leaf-venation-directed cellular alignment for macroscale cardiac constructs with tissue-like functionalities

Recapitulating the complex structural, mechanical, and electrophysiological properties of native myocardium is crucial to engineering functional cardiac tissues. Here, we report a leaf-venation-directed strategy that enables the compaction and remodeling of cell-hydrogel hybrids into highly aligned and densely packed organizations in predetermined patterns. This strategy contributes to interconnected tubular structures with cell alignment along the hierarchical channels. Compared to randomly-distributed cells, the engineered leaf-venation-directed-cardiac tissues from neonatal rat cardiomyocytes manifest advanced maturation and functionality as evidenced by detectable electrophysiological activity, macroscopically synchronous contractions, and upregulated maturation genes. As a demonstration, human induced pluripotent stem cell-derived leaf-venation-directed-cardiac tissues are engineered with evident structural and functional improvement over time. With the elastic scaffolds, leaf-venation-directed tissues are assembled into 3D centimeter-scale cardiac constructs with programmed mechanical properties, which can be delivered through tubing without affecting cell viability. The present strategy may generate cardiac constructs with multifaceted functionalities to meet clinical demands.

Progress in Biomaterials for Cardiac Tissue Engineering and Regeneration

Cardiovascular diseases are one of the leading global causes of morbidity and mortality, posing considerable health and economic burden on patients and medical systems worldwide. This phenomenon is attributed to two main motives: poor regeneration capacity of adult cardiac tissues and insufficient therapeutic options. Thus, the context calls for upgrading treatments to deliver better outcomes. In this respect, recent research has approached the topic from an interdisciplinary perspective. Combining the advances encountered in chemistry, biology, material science, medicine, and nanotechnology, performant biomaterial-based structures have been created to carry different cells and bioactive molecules for repairing and restoring heart tissues. In this regard, this paper aims to present the advantages of biomaterial-based approaches for cardiac tissue engineering and regeneration, focusing on four main strategies: cardiac patches, injectable hydrogels, extracellular vesicles, and scaffolds and reviewing the most recent developments in these fields.

Promising Clinical Applications of Hydrogels Associated With Precise Cancer Treatment: A Review

Gastrointestinal cancer is one of the most malignant tumors with high morbidity and mortality, especially colorectal cancer, which has become the second leading cause of cancer-related deaths worldwide. Targeted drug treatment and precise endoscopic resection can significantly improve the overall survival rate and greatly extend the life span. Promising biomedical applications of hydrogels would represent hopeful therapeutic alternatives for patients with different kinds of diseases, particularly providing precise therapy for cancer patients. Although the intersection field of material science and biomedical science has made tremendous advances, major challenges remain. In this review, the application of hydrogel-based technology in cancer precision medicine is the focus of attention, which is the development trend of multidisciplinary cooperation in the future. First, we provide the current clinical landscape of hydrogel applications, and then we highlight precision oncology, including personalized drug treatment and accurate endoscopic intervention. Finally, we discuss major challenges for their clinical translation that have not yet been overcome and future perspectives on cancer precision medicine.

Design and Fabrication of Mature Engineered Pre-Cardiac Tissue Utilizing 3D Bioprinting Technology and Enzymatically Crosslinking Hydrogel

The fabrication of mature engineered cardiac tissue is one of the major challenges in cardiac tissue engineering. For this purpose, we attempted to apply the 3D bioprinting approach. Aiming to construct an oriented tissue, a fine fiber-shaped scaffold with a support structure was first designed using CAD software. Then, a 3D bioprinter and cell-adhesive bio-inks were utilized to fabricate this structure. The cell-adhesive bio-inks were synthesized by combining sodium alginate and gelatin with tyramine, respectively, to form pre-gel materials that allow enzymatic crosslinking by horseradish peroxidase. By absorbance measurements, we confirmed that the tyramine modification rate of each polymer was 0.535 mmol/g-alginate and 0.219 mmol/g-gelatin. The width of the fiber-shaped scaffold was 216.8 ± 24.3 μm for the fabricated scaffold, while the design value was 200 μm. After 3D printing and adhesion-adding treatment of the scaffold with these bio-ink materials, cardiomyocytes were seeded and cultured. As a result, the cells spread onto the scaffold, and the entire pre-tissue contracted synchronously by day 6 of culture, showing a greater pulsatility than in the early days. Video analysis showed that the beating rate of pre-myocardial tissue on day 6 was 31 beats/min. In addition, we confirmed that the cardiomyocytes partially elongated along the long axis of the fiber-shaped scaffold in the pre-tissue cultured for 15 days by staining actin, suggesting the possibility of cell orientation. Furthermore, treatment with adrenaline resulted in a 7.7-fold increase in peak beating rate compared to that before treatment (from 6 beats/min to 46 beats/min), confirming the responsiveness of the pre-tissues to the drug. These results indicate that 3D bioprinting effectively produces mature cultured myocardial tissue that is oriented, contracts synchronously, and is responsive to drugs.

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.

An Intrapericardial Injectable Hydrogel Patch for Mechanical-Electrical Coupling with Infarcted Myocardium

Although hydrogel-based patches have shown promising therapeutic efficacy in myocardial infarction (MI), synergistic mechanical, electrical, and biological cues are required to restore cardiac electrical conduction and diastolic-systolic function. Here, an injectable mechanical-electrical coupling hydrogel patch (MEHP) is developed via dynamic covalent/noncovalent cross-linking, appropriate for cell encapsulation and minimally invasive implantation into the pericardial cavity. Pericardial fixation and hydrogel self-adhesiveness properties enable the MEHP to highly compliant interfacial coupling with cyclically deformed myocardium. The self-adaptive MEHP inhibits ventricular dilation while assisting cardiac pulsatile function. The MEHP with the electrical conductivity and sensitivity to match myocardial tissue improves electrical connectivity between healthy and infarcted areas and increases electrical conduction velocity and synchronization. Overall, the MEHP combined with cell therapy effectively prevents ventricular fibrosis and remodeling, promotes neovascularization, and restores electrical propagation and synchronized pulsation, facilitating the clinical translation of cardiac tissue engineering.

Cell-Based and Selected Cell-Free Therapies for Myocardial Infarction: How Do They Compare to the Current Treatment Options?

Because of cardiomyocyte death or dysfunction frequently caused by myocardial infarction (MI), heart failure is a leading cause of morbidity and mortality in modern society. Paradoxically, only limited and non-curative therapies for heart failure or MI are currently available. As a result, over the past two decades research has focused on developing cell-based approaches promoting the regeneration of infarcted tissue. Cell-based therapies for myocardial regeneration include powerful candidates, such as multipotent stem cells (mesenchymal stem cells (MSCs), bone-marrow-derived stem cells, endothelial progenitor cells, and hematopoietic stem cells) and induced pluripotent stem cells (iPSCs). These possess unique properties, such as potency to differentiate into desired cell types, proliferation capacity, and patient specificity. Preclinical and clinical studies have demonstrated modest improvement in the myocardial regeneration and reduced infarcted areas upon transplantation of pluripotent or multipotent stem cells. Another cell population that need to be considered as a potential source for cardiac regeneration are telocytes found in different organs, including the heart. Their therapeutic effect has been studied in various heart pathologies, such as MI, arrhythmias, or atrial amyloidosis. The most recent cell-free therapeutic tool relies on the cardioprotective effect of complex cargo carried by small membrane-bound vesicles—exosomes—released from stem cells via exocytosis. The MSC/iPSC-derived exosomes could be considered a novel exosome-based therapy for cardiovascular diseases thanks to their unique content. There are also other cell-free approaches, e.g., gene therapy, or acellular cardiac patches. Therefore, our review provides the most recent insights into the novel strategies for myocardial repair based on the regenerative potential of different cell types and cell-free approaches.

Paclitaxel and Urolithin A Prevent Histamine-Induced Neurovascular Breakdown Alike, in an Ex Vivo Rat Eye Model

Neurovascular eye problems are better prevented than managed or treated. Despite growing concern of occurrence in aging populations and development secondary to diseases such as diabetes and hypertension, we currently have very few options to tackle this global problem. Creating effective and high-throughput screening strategies is as important as the intervention itself. Here, we present for the first time a robust ex vivo rat eye model of histamine-induced vascular damage for investigating the therapeutic potential of paclitaxel (PTX) and urolithin A (UA) as alternatives to dexamethasone for preventing vascular damage in the retina. Extensive loss of vascularization and apoptosis were observed in the histamine-challenged group and successfully prevented in the intervention groups, more significantly in the PTX and UA. These important early results indicate that PTX and UA could be developed as potential preventive strategies for a wide variety of retinal diseases.

Review of the Recent Advances in Electrospun Nanofibers Applications in Water Purification

Recently, nanofibers have come to be considered one of the sustainable routes with enormous applicability in different fields, such as wastewater treatment. Electrospun nanofibers can be fabricated from various materials, such as synthetic and natural polymers, and contribute to the synthesis of novel nanomaterials and nanocomposites. Therefore, they have promising properties, such as an interconnected porous structure, light weight, high porosity, and large surface area, and are easily modified with other polymeric materials or nanomaterials to enhance their suitability for specific applications. As such, this review surveys recent progress made in the use of electrospun nanofibers to purify polluted water, wherein the distinctive characteristics of this type of nanofiber are essential when using them to remove organic and inorganic pollutants from wastewater, as well as for oil/water (O/W) separation.

Recent Progress and Potential Biomedical Applications of Electrospun Nanofibers in Regeneration of Tissues and Organs

Electrospun techniques are promising and flexible technologies to fabricate ultrafine fiber/nanofiber materials from diverse materials with unique characteristics under optimum conditions. These fabricated fibers/nanofibers via electrospinning can be easily assembled into several shapes of three-dimensional (3D) structures and can be combined with other nanomaterials. Therefore, electrospun nanofibers, with their structural and functional advantages, have gained considerable attention from scientific communities as suitable candidates in biomedical fields, such as the regeneration of tissues and organs, where they can mimic the network structure of collagen fiber in its natural extracellular matrix(es). Due to these special features, electrospinning has been revolutionized as a successful technique to fabricate such nanomaterials from polymer media. Therefore, this review reports on recent progress in electrospun nanofibers and their applications in various biomedical fields, such as bone cell proliferation, nerve regeneration, and vascular tissue, and skin tissue, engineering. The functionalization of the fabricated electrospun nanofibers with different materials furnishes them with promising properties to enhance their employment in various fields of biomedical applications. Finally, we highlight the challenges and outlooks to improve and enhance the application of electrospun nanofibers in these applications.

Taking It Personally: 3D Bioprinting a Patient-Specific Cardiac Patch for the Treatment of Heart Failure

Despite a massive global preventative effort, heart failure remains the major cause of death globally. The number of patients requiring a heart transplant, the eventual last treatment option, far outnumbers the available donor hearts, leaving many to deteriorate or die on the transplant waiting list. Treating heart failure by transplanting a 3D bioprinted patient-specific cardiac patch to the infarcted region on the myocardium has been investigated as a potential future treatment. To date, several studies have created cardiac patches using 3D bioprinting; however, testing the concept is still at a pre-clinical stage. A handful of clinical studies have been conducted. However, moving from animal studies to human trials will require an increase in research in this area. This review covers key elements to the design of a patient-specific cardiac patch, divided into general areas of biological design and 3D modelling. It will make recommendations on incorporating anatomical considerations and high-definition motion data into the process of 3D-bioprinting a patient-specific cardiac patch.

Main Applications and Recent Research Progresses of Additive Manufacturing in Dentistry

In recent ten years, with the fast development of digital and engineering manufacturing technology, additive manufacturing has already been more and more widely used in the field of dentistry, from the first personalized surgical guides to the latest personalized restoration crowns and root implants. In particular, the bioprinting of teeth and tissue is of great potential to realize organ regeneration and finally improve the life quality. In this review paper, we firstly presented the workflow of additive manufacturing technology. Then, we summarized the main applications and recent research progresses of additive manufacturing in dentistry. Lastly, we sketched out some challenges and future directions of additive manufacturing technology in dentistry.

Regenerative strategies for the consequences of myocardial infarction: Chronological indication and upcoming visions

Heart muscle injury and an elevated troponin level signify myocardial infarction (MI), which may result in defective and uncoordinated segments, reduced cardiac output, and ultimately, death. Physicians apply thrombolytic therapy, coronary artery bypass graft (CABG) surgery, or percutaneous coronary intervention (PCI) to recanalize and restore blood flow to the coronary arteries, albeit they were not convincingly able to solve the heart problems. Thus, researchers aim to introduce novel substitutional therapies for regenerating and functionalizing damaged cardiac tissue based on engineering concepts. Cell-based engineering approaches, utilizing biomaterials, gene, drug, growth factor delivery systems, and tissue engineering are the most leading studies in the field of heart regeneration. Also, understanding the primary cause of MI and thus selecting the most efficient treatment method can be enhanced by preparing microdevices so-called heart-on-a-chip. In this regard, microfluidic approaches can be used as diagnostic platforms or drug screening in cardiac disease treatment. Additionally, bioprinting technique with whole organ 3D printing of human heart with major vessels, cardiomyocytes and endothelial cells can be an ideal goal for cardiac tissue engineering and remarkable achievement in near future. Consequently, this review discusses the different aspects, advancements, and challenges of the mentioned methods with presenting the advantages and disadvantages, chronological indications, and application prospects of various novel therapeutic approaches.