Progress in Biomaterials for Cardiac Tissue Engineering and Regeneration

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

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

Materials Advances in Devices for Heart Disease Interventions

Heart disease encompasses a range of conditions that affect the heart, including coronary artery disease, arrhythmias, congenital heart defects, heart valve disease, and conditions that affect the heart muscle. Intervention strategies can be categorized according to when they are administered and include: 1) Monitoring cardiac function using sensor technology to inform diagnosis and treatment, 2) Managing symptoms by restoring cardiac output, electrophysiology, and hemodynamics, and often serving as bridge-to-recovery or bridge-to-transplantation strategies, and 3) Repairing damaged tissue, including myocardium and heart valves, when management strategies are insufficient. Each intervention approach and technology require specific material properties to function optimally, relying on materials that support their action and interface with the body, with new technologies increasingly depending on advances in materials science and engineering. This review explores material properties and requirements driving innovation in advanced intervention strategies for heart disease and highlights key examples of recent progress in the field driven by advances in materials research.

Biomimetic Polyurethanes in Tissue Engineering

Inspiration from nature is a promising tool for the design of new polymeric biomaterials, especially for frontier technological areas such as tissue engineering. In tissue engineering, polyurethane-based implants have gained considerable attention, as they are materials that can be designed to meet the requirements imposed by their final applications. The choice of their building blocks (which are used in the synthesis as macrodiols, diisocyanates, and chain extenders) can be implemented to obtain biomimetic structures that can mimic native tissue in terms of mechanical, morphological, and surface properties. In recent years, due to their excellent chemical stability, biocompatibility, and low cytotoxicity, polyurethanes have been widely used in biomedical applications. Biomimetic materials, with their inherent nature of mimicking natural materials, are possible thanks to recent advances in manufacturing technology. The aim of this review is to provide a critical overview of relevant promising studies on polyurethane scaffolds, including those based on non-isocyanate polyurethanes, for the regeneration of selected soft (cardiac muscle, blood vessels, skeletal muscle) and hard (bone tissue) tissues.

Advances in Conductive Biomaterials for Cardiac Tissue Engineering: Design, Fabrication, and Functional Integration

Heart failure functions as one of the leading global causes of death because it falls under the cardiovascular disease categories. Cardiac tissue engineering advances by developing new tissues to rebuild heart functions in individuals with damaged heart structures as it gives medical treatment possibilities to patients reaching their final stage. Most of the heart tissue consists of cardiomyocytes which make up between 80 to 90 percent of the total organ space. The cardiomyocytes retain their specialized cell structure which includes elongation, but they align to produce contractions as they span into length. After myocardial infarction, doctors need elastic soft platforms to heal the heart tissue because they mimic its natural attributes. Special consideration must be paid to the material selection for appropriate mechanical properties, given that different substances have separate qualities. Stem cell survival becomes higher, and cell differentiation develops more efficiently when a proper scaffold design is implemented, thus enabling tissue repair. Conductive biomaterials demonstrate the best candidate status for cardiac tissue engineering due to their ability to both convey electrical signals and boost biological actions as well as promote cellular communication. Scientists conduct life science research on stem cells because the cells present unique characteristics. Biomaterials with conductive properties within cardiac tissue engineering help the body recover heart tissue while improving the functionality of damaged structures in the myocardium. This article analyzes various conductive biomaterials used in biomedical practices for cardiac tissue healing applications.

A comprehensive review on guar gum and its modified biopolymers: Their potential applications in tissue engineering

Guar gum (GG), as a non-exudate gum, is extracted from the seed's embryos of Cyamopsis tetragonoloba (a member of Leguminosae family). Recently, this biopolymer has received extensive attention due to its low cost, notable properties, non-toxic biodegradation, ease of availability, and biocompatibility. However, disadvantages such as uncontrolled hydration rate and susceptibility to microbial attack have led many researchers to further modification of guar gum. Further modifications of guar gum heteropolysaccharide have been performed to improve properties and explore and expand its potential. The favorable biostability, improved solubility, and swelling, increased pH sensitivity, and good antibacterial and antioxidant properties indicate the significant advantages of the modified gum structures with different functional groups. In this review, the rapid growth in research on GG derivatives-based materials has been discovered. Besides, the production methods of GG and its derivatives have been discussed in tissue engineering and regenerative medical. Consequently, this review highlights the advances in the production of guar-based products to outline a promising future for this biopolymer by changing its properties and expanding its applications in potential targets.

Current Advances and Future Directions of Pluripotent Stem Cells-Derived Engineered Heart Tissue for Treatment of Cardiovascular Diseases

Cardiovascular diseases resulting from myocardial infarction (MI) remain a leading cause of death worldwide, imposing a substantial burden on global health systems. Current MI treatments, primarily pharmacological and surgical, do not regenerate lost myocardium, leaving patients at high risk for heart failure. Engineered heart tissue (EHT) offers a promising solution for MI and related cardiac conditions by replenishing myocardial loss. However, challenges like immune rejection, inadequate vascularization, limited mechanical strength, and incomplete tissue maturation hinder clinical application. The discovery of human-induced pluripotent stem cells (hiPSCs) has transformed the EHT field, enabling new bioengineering innovations. This review explores recent advancements and future directions in hiPSC-derived EHTs, focusing on innovative materials and fabrication methods like bioprinting and decellularization, and assessing their therapeutic potential through preclinical and clinical studies. Achieving functional integration of EHTs in the heart remains challenging due to the need for synchronized contraction, sufficient vascularization, and mechanical compatibility. Solutions such as genome editing, personalized medicine, and AI technologies offer promising strategies to address these translational barriers. Beyond MI, EHTs also show potential in treating ischemic cardiomyopathy, heart valve engineering, and drug screening, underscoring their promise in cardiovascular regenerative medicine.

Exosomes derived from Danshen decoction-pretreated bone marrow mesenchymal stem cells alleviate myocardial infarction via anti-apoptosis and up-regulation of autophagy

Cardiomyocyte loss and myocardial fibrosis are major determinants of myocardial infarction (MI) pathological changes. Mesenchymal stem cell (MSC)-derived exosomes (exos) and Danshen decoction (DSY) have been demonstrated to mediate cardiac repair following MI. BM-MSCs exos or BM-MSCsDSY exos were intramuscularly injected into post-MI rats. On the 7th, 14th and 28th days, serum CK, LDH, α-HBDH, ALT, and AST were measured and electrocardiogram changes were monitored to identify cardiac function; Triphenyltetrazolium chloride staining, Hematein&Eosin staining, Masson trichrome staining and Transmission Electron Microscope were adopted to analyze infarct area, cardiac morphology, histopathology, and fibrosis and cardiomyocyte ultrastructure; TUNEL assay, real-time PCR and western blot were performed to detect cardiomyocyte apoptosis and autophagy. As a result, BMMSCsDSY exos are superior to BM-MSCs-exos in improvement of cardiac function, morphology, histopathology and cardiomyocyte ultrastructure, as well as in reduction of infarction area and cardiac fibrosis by inhibiting apoptosis and promoting autophagy of cardiomyocytes.

Stem cell-based therapy for fibrotic diseases: mechanisms and pathways

Fibrosis is a pathological process, that could result in permanent scarring and impairment of the physiological function of the affected organ; this condition which is categorized under the term organ failure could affect various organs in different situations. The involvement of the major organs, such as the lungs, liver, kidney, heart, and skin, is associated with a high rate of morbidity and mortality across the world. Fibrotic disorders encompass a broad range of complications and could be traced to various illnesses and impairments; these could range from simple skin scars with beauty issues to severe rheumatologic or inflammatory disorders such as systemic sclerosis as well as idiopathic pulmonary fibrosis. Besides, the overactivation of immune responses during any inflammatory condition causing tissue damage could contribute to the pathogenic fibrotic events accompanying the healing response; for instance, the inflammation resulting from tissue engraftment could cause the formation of fibrotic scars in the grafted tissue, even in cases where the immune system deals with hard to clear infections, fibrotic scars could follow and cause severe adverse effects. A good example of such a complication is post-Covid19 lung fibrosis which could impair the life of the affected individuals with extensive lung involvement. However, effective therapies that halt or slow down the progression of fibrosis are missing in the current clinical settings. Considering the immunomodulatory and regenerative potential of distinct stem cell types, their application as an anti-fibrotic agent, capable of attenuating tissue fibrosis has been investigated by many researchers. Although the majority of the studies addressing the anti-fibrotic effects of stem cells indicated their potent capabilities, the underlying mechanisms, and pathways by which these cells could impact fibrotic processes remain poorly understood. Here, we first, review the properties of various stem cell types utilized so far as anti-fibrotic treatments and discuss the challenges and limitations associated with their applications in clinical settings; then, we will summarize the general and organ-specific mechanisms and pathways contributing to tissue fibrosis; finally, we will describe the mechanisms and pathways considered to be employed by distinct stem cell types for exerting anti-fibrotic events.

3D Printing of Polysaccharide-Based Hydrogel Scaffolds for Tissue Engineering Applications: A Review

In tissue engineering, 3D printing represents a versatile technology employing inks to construct three-dimensional living structures, mimicking natural biological systems. This technology efficiently translates digital blueprints into highly reproducible 3D objects. Recent advances have expanded 3D printing applications, allowing for the fabrication of diverse anatomical components, including engineered functional tissues and organs. The development of printable inks, which incorporate macromolecules, enzymes, cells, and growth factors, is advancing with the aim of restoring damaged tissues and organs. Polysaccharides, recognized for their intrinsic resemblance to components of the extracellular matrix have garnered significant attention in the field of tissue engineering. This review explores diverse 3D printing techniques, outlining distinctive features that should characterize scaffolds used as ideal matrices in tissue engineering. A detailed investigation into the properties and roles of polysaccharides in tissue engineering is highlighted. The review also culminates in a profound exploration of 3D polysaccharide-based hydrogel applications, focusing on recent breakthroughs in regenerating different tissues such as skin, bone, cartilage, heart, nerve, vasculature, and skeletal muscle. It further addresses challenges and prospective directions in 3D printing hydrogels based on polysaccharides, paving the way for innovative research to fabricate functional tissues, enhancing patient care, and improving quality of life.

Biomaterials for direct cardiac repair-A rapid scoping review 2012-2022

A plethora of biomaterials for heart repair are being tested worldwide for potential clinical application. These therapeutics aim to enhance the quality of life of patients with heart disease using various methods to improve cardiac function. Despite the myriad of therapeutics tested, only a minority of these studied biomaterials have entered clinical trials. This rapid scoping review aims to analyze literature available from 2012 to 2022 with a focus on clinical trials using biomaterials for direct cardiac repair, i.e., where the intended function of the biomaterial is to enhance the repair of the endocardium, myocardium, epicardium or pericardium. This review included neither biomaterials related to stents and valve repair nor biomaterials serving as vehicles for the delivery of drugs. Surprisingly, the literature search revealed that only 8 different biomaterials mentioned in 23 different studies out of 7038 documents (journal articles, conference abstracts or clinical trial entries) have been tested in clinical trials since 2012. All of these, intended to treat various forms of ischaemic heart disease (heart failure, myocardial infarction), were of natural origin and most used direct injections as their delivery method. This review thus reveals notable gaps between groups of biomaterials tested pre-clinically and clinically. STATEMENT OF SIGNIFICANCE: Rapid scoping review of clinical application of biomaterials for cardiac repair. 7038 documents screened; 23 studies mention 8 different biomaterials only. Biomaterials for repair of endocardium, myocardium, epicardium or pericardium. Only 8 different biomaterials entered clinical trials in the past 10 years. All of the clinically translated biomaterials were of natural origin.

Progress in cardiac tissue engineering and regeneration: Implications of gelatin-based hybrid scaffolds

Cardiovascular diseases, particularly myocardial infarction (MI), remain a leading cause of morbidity and mortality worldwide. Current treatments for MI, more palliative than curative, have limitations in reversing the disease completely. Tissue engineering (TE) has emerged as a promising strategy to address this challenge and may lead to improved therapeutic approaches for MI. Gelatin-based scaffolds, including gelatin and its derivative, gelatin methacrylate (GelMA), have attracted significant attention in cardiac tissue engineering (CTE) due to their optimal physical and biochemical properties and capacity to mimic the native extracellular matrix (ECM). CTE mainly recruits two classes of gelatin/GelMA-based scaffolds: hydrogels and nanofibrous. This article reviews state-of-the-art gelatin/GelMA-based hybrid scaffolds currently applied for CTE and regenerative therapy. Hybrid scaffolds, fabricated by combining gelatin/GelMA hydrogel or nanofibrous scaffolds with other materials such as natural/synthetic polymers, nanoparticles, protein-based biomaterials, etc., are explored for enhanced cardiac tissue regeneration functionality. The engraftment of stem/cardiac cells, bioactive molecules, or drugs into these hybrid systems shows great promise in cardiac tissue repair and regeneration. Finally, the role of gelatin/GelMA scaffolds combined with the 3D bioprinting strategy in CTE will also be briefly highlighted.

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

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

The Long and Winding Road to Cardiac Regeneration

Cardiac regeneration is a critical endeavor in the treatment of heart diseases, aimed at repairing and enhancing the structure and function of damaged myocardium. This review offers a comprehensive overview of current advancements and strategies in cardiac regeneration, with a specific focus on regenerative medicine and tissue engineering-based approaches. Stem cell-based therapies, which involve the utilization of adult stem cells and pluripotent stem cells hold immense potential for replenishing lost cardiomyocytes and facilitating cardiac tissue repair and regeneration. Tissue engineering also plays a prominent role employing synthetic or natural biomaterials, engineering cardiac patches and grafts with suitable properties, and fabricating upscale bioreactors to create functional constructs for cardiac recovery. These constructs can be transplanted into the heart to provide mechanical support and facilitate tissue healing. Additionally, the production of organoids and chips that accurately replicate the structure and function of the whole organ is an area of extensive research. Despite significant progress, several challenges persist in the field of cardiac regeneration. These include enhancing cell survival and engraftment, achieving proper vascularization, and ensuring the long-term functionality of engineered constructs. Overcoming these obstacles and offering effective therapies to restore cardiac function could improve the quality of life for individuals with heart diseases.

Cells and Materials for Cardiac Repair and Regeneration

After more than 20 years following the introduction of regenerative medicine to address the problem of cardiac diseases, still questions arise as to the best cell types and materials to use to obtain effective clinical translation. Now that it is definitively clear that the heart does not have a consistent reservoir of stem cells that could give rise to new myocytes, and that there are cells that could contribute, at most, with their pro-angiogenic or immunomodulatory potential, there is fierce debate on what will emerge as the winning strategy. In this regard, new developments in somatic cells' reprogramming, material science and cell biophysics may be of help, not only for protecting the heart from the deleterious consequences of aging, ischemia and metabolic disorders, but also to boost an endogenous regeneration potential that seems to be lost in the adulthood of the human heart.