Alginate biomaterial for the treatment of myocardial infarction: Progress, translational strategies, and clinical outlook: From ocean algae to patient bedside

Mechanochemistry: Fundamental Principles and Applications

Mechanochemistry is an emerging research field at the interface of physics, mechanics, materials science, and chemistry. Complementary to traditional activation methods in chemistry, such as heat, electricity, and light, mechanochemistry focuses on the activation of chemical reactions by directly or indirectly applying mechanical forces. It has evolved as a powerful tool for controlling chemical reactions in solid state systems, sensing and responding to stresses in polymer materials, regulating interfacial adhesions, and stimulating biological processes. By combining theoretical approaches, simulations and experimental techniques, researchers have gained intricate insights into the mechanisms underlying mechanochemistry. In this review, the physical chemistry principles underpinning mechanochemistry are elucidated and a comprehensive overview of recent significant achievements in the discovery of mechanically responsive chemical processes is provided, with a particular emphasis on their applications in materials science. Additionally, The perspectives and insights into potential future directions for this exciting research field are offered.

Pericardial Delivery of Sodium Alginate-Infusible Extracellular Matrix Composite Hydrogel Promotes Angiogenesis and Intercellular Electrical Conduction after Myocardial Infarction

Injectable extracellular matrix (iECM) is a versatile biological material with beneficial properties such as good degradability, promotion of cell survival, immunomodulation, and facilitation of vascular formation. However, intravenous injection of iECM faces challenges like a short retention time in vivo and low concentration at the lesion site. To address these issues, we prepared a composite hydrogel composed of sodium alginate and iECM and administered it via intrapericardial injection, forming a structure akin to cardiac patches within the pericardium. Compared with intramyocardial injection, intrapericardial injection avoids direct myocardial injury and ectopic tumor formation, offering less invasiveness and better biocompatibility. This study demonstrates that the sodium alginate/infusible extracellular matrix (SA/iECM) composite hydrogel can effectively prolong the local retention time of iECM in the heart, enhance electrical conduction between cardiomyocytes, promote angiogenesis at ischemic myocardial sites, inhibit apoptosis in the infarcted region, mitigate left ventricular remodeling postmyocardial infarction (MI), and improve cardiac function after infarction. Precise coordination of cardiomyocyte contraction and relaxation depends on the rhythmic occurrence of calcium-dependent action potentials. Cardiac dysfunction is partially attributed to the disruption of the excitation-contraction coupling (ECC) mechanism, which is associated with prolonged intracellular Ca2+ transients and alterations in contraction and relaxation Ca2+ levels. Our results show that the SA/iECM composite hydrogel improves electrical conduction, as evidenced by increased Cx43 expression and enhanced intercellular electrical connectivity. This research establishes that intrapericardial injection of a SA/iECM composite hydrogel is a safe and effective treatment modality, providing a theoretical basis for the use of biomaterials in MI therapy.

Alginate-based artificial antigen presenting cells expand functional CD8+ T cells with memory characteristics for adoptive cell therapy

The development of artificial Antigen Presenting Cells (aAPCs) has led to improvements in adoptive T cell therapy (ACT), an immunotherapy, for cancer treatment. aAPCs help to streamline the consistent production and expansion of T cells, thus reducing the time and costs associated with ACT. However, several issues still exist with ACT, such as insufficient T cell potency, which diminishes the translational potential for ACT. While aAPCs have been used primarily to increase production efficiency of T cells for ACT, the intrinsic properties of a biomaterial-based aAPC may affect T cell phenotype and function. In CD8+ T cells, reactive oxygen species (ROS) and oxidative stress accumulation can activate Forkhead box protein O1 (FOXO1) to transcribe antioxidants which reduce ROS and improve memory formation. Alginate, a biocompatible and antioxidant rich biomaterial, is promising for incorporation into an aAPC formulation to modulate T cell phenotype. To investigate its utility, a novel alginate-based aAPC platform was developed that preferentially expanded CD8+ T cells with memory related features. Alginate-based aAPCs allowed for greater control of CD8+ T cell qualities, including, significantly improved in vivo persistence and augmented in vivo anti-tumor T cell responses.

Bioinspired Adaptive Microdrugs Enhance the Chemotherapy of Malignant Glioma: Beyond Their Nanodrugs

Solid nanoparticle-mediated drug delivery systems are usually confined to nanoscale due to the enhanced permeability and retention effect. However, they remain a great challenge for malignant glioma chemotherapy because of poor drug delivery efficiency and insufficient tumor penetration resulting from the blood-brain barrier/blood-brain tumor barrier (BBB/BBTB). Inspired by biological microparticles (e.g., cells) with excellent adaptive deformation, it is demonstrated that the adaptive microdrugs (even up to 3.0 µm in size) are more efficient than their nanodrugs (less than 200 nm in size) to cross BBB/BBTB and penetrate into tumor tissues, achieving highly efficient chemotherapy of malignant glioma. The distinct delivery of the adaptive microdrugs is mainly attributed to the enhanced interfacial binding and endocytosis via adaptive deformation. As expected, the obtained adaptive microdrugs exhibit enhanced accumulation, deep penetration, and cellular internalization into tumor tissues in comparison with nanodrugs, significantly improving the survival rate of glioblastoma mice. It is believed that the bioinspired adaptive microdrugs enable them to efficiently cross physiological barriers and deeply penetrate tumor tissues for drug delivery, providing an avenue for the treatment of solid tumors.

Hydrogel-Based 3D Bioprinting Technology for Articular Cartilage Regenerative Engineering

Articular cartilage is an avascular tissue with very limited capacity of self-regeneration. Trauma or injury-related defects, inflammation, or aging in articular cartilage can induce progressive degenerative joint diseases such as osteoarthritis. There are significant clinical demands for the development of effective therapeutic approaches to promote articular cartilage repair or regeneration. The current treatment modalities used for the repair of cartilage lesions mainly include cell-based therapy, small molecules, surgical approaches, and tissue engineering. However, these approaches remain unsatisfactory. With the advent of three-dimensional (3D) bioprinting technology, tissue engineering provides an opportunity to repair articular cartilage defects or degeneration through the construction of organized, living structures composed of biomaterials, chondrogenic cells, and bioactive factors. The bioprinted cartilage-like structures can mimic native articular cartilage, as opposed to traditional approaches, by allowing excellent control of chondrogenic cell distribution and the modulation of biomechanical and biochemical properties with high precision. This review focuses on various hydrogels, including natural and synthetic hydrogels, and their current developments as bioinks in 3D bioprinting for cartilage tissue engineering. In addition, the challenges and prospects of these hydrogels in cartilage tissue engineering applications are also discussed.

Annexin A1-Loaded Alginate Hydrogel Promotes Cardiac Repair via Modulation of Macrophage Phenotypes after Myocardial Infarction

Myocardial infarction (MI) is associated with inflammatory reaction, which is a pivotal component in MI pathogenesis. Moreover, excessive inflammation post-MI can lead to cardiac dysfunction and adverse remodeling, emphasizing the critical need for an effective inflammation-regulating treatment for cardiac repair. Macrophage polarization is crucial in the inflammation process, indicating its potential as an adjunct therapy for MI. In this study, we developed an injectable alginate hydrogel loaded with annexin A1 (AnxA1, an endogenous anti-inflammatory and pro-resolving mediator) for MI treatment. In vitro results showed that the composite hydrogel had good biocompatibility and consistently released AnxA1 for several days. Additionally, this hydrogel led to a reduced number of pro-inflammatory macrophages and an increased proportion of pro-healing macrophages via the adenosine monophosphate (AMP)-activated protein kinase (AMPK)-mammalian target of the rapamycin (mTOR) axis. Furthermore, the intramyocardial injection of this composite hydrogel into a mouse MI model effectively modulated macrophage transition to pro-healing phenotypes. This transition mitigated early inflammatory responses and cardiac fibrosis, promoted angiogenesis, and improved cardiac function. Therefore, our study findings suggest that combining biomaterials and endogenous proteins for MI treatment is a promising approach for limiting adverse cardiac remodeling, preventing cardiac damage, and preserving the function of infarcted hearts.

Incorporation of Decidual Stromal Cells Derived Exosomes in Sodium Alginate Hydrogel as an Innovative Therapeutic Strategy for Advancing Endometrial Regeneration and Reinstating Fertility

Intrauterine adhesion (IUA) stands as a prevalent medical condition characterized by endometrial fibrosis and scar tissue formation within the uterine cavity, resulting in infertility and, in severe cases, recurrent miscarriages. Cell therapy, especially with stem cells, offers an alternative to surgery, but concerns about uncontrolled differentiation and tumorigenicity limit its use. Exosomes, more stable and immunogenicity-reduced than parent cells, have emerged as a promising avenue for IUA treatment. In this study, a novel approach has been proposed wherein exosomes originating from decidual stromal cells (DSCs) are encapsulated within sodium alginate hydrogel (SAH) scaffolds to repair endometrial damage and restore fertility in a mouse IUA model. Current results demonstrate that in situ injection of DSC-derived exosomes (DSC-exos)/SAH into the uterine cavity has the capability to induce uterine angiogenesis, initiate mesenchymal-to-epithelial transformation (MET), facilitate collagen fiber remodeling and dissolution, promote endometrial regeneration, enhance endometrial receptivity, and contribute to the recovery of fertility. RNA sequencing and advanced bioinformatics analysis reveal miRNA enrichment in exosomes, potentially supporting endometrial repair. This finding elucidates how DSC-exos/SAH mechanistically fosters collagen ablation, endometrium regeneration, and fertility recovery, holding the potential to introduce a novel IUA treatment and offering invaluable insights into the realm of regenerative medicine.

Advances in injectable hydrogels for radiation-induced heart disease

Radiological heart damage (RIHD) is damage caused by unavoidable irradiation of the heart during chest radiotherapy, with a long latency period and a progressively increasing proportion of delayed cardiac damage due to conventional doses of chest radiotherapy. There is a risk of inducing diseases such as acute/chronic pericarditis, myocarditis, delayed myocardial fibrosis and damage to the cardiac conduction system in humans, which can lead to myocardial infarction or even death in severe cases. This paper details the pathogenesis of RIHD and gives potential targets for treatment at the molecular and cellular level, avoiding the drawbacks of high invasiveness and immune rejection due to drug therapy, medical device implantation and heart transplantation. Injectable hydrogel therapy has emerged as a minimally invasive tissue engineering therapy to provide necessary mechanical support to the infarcted myocardium and to act as a carrier for various bioactive factors and cells to improve the cellular microenvironment in the infarcted area and induce myocardial tissue regeneration. Therefore, this paper combines bioactive factors and cellular therapeutic mechanisms with injectable hydrogels, presents recent advances in the treatment of cardiac injury after RIHD with different injectable gels, and summarizes the therapeutic potential of various types of injectable hydrogels as a potential solution.

Hydrogel-based cardiac repair and regeneration function in the treatment of myocardial infarction

A life-threatening illness that poses a serious threat to human health is myocardial infarction. It may result in a significant number of myocardial cells dying, dilated left ventricles, dysfunctional heart function, and ultimately cardiac failure. Based on the development of emerging biomaterials and the lack of clinical treatment methods and cardiac donors for myocardial infarction, hydrogels with good compatibility have been gradually applied to the treatment of myocardial infarction. Specifically, based on the three processes of pathophysiology of myocardial infarction, we summarized various types of hydrogels designed for myocardial tissue engineering in recent years, including natural hydrogels, intelligent hydrogels, growth factors, stem cells, and microRNA-loaded hydrogels. In addition, we also describe the heart patch and preparation techniques that promote the repair of MI heart function. Although most of these hydrogels are still in the preclinical research stage and lack of clinical trials, they have great potential for further application in the future. It is expected that this review will improve our knowledge of and offer fresh approaches to treating myocardial infarction.

Recent Advances in Alginate-Based Hydrogels for Cell Transplantation Applications

With its exceptional biocompatibility, alginate emerged as a highly promising biomaterial for a large range of applications in regenerative medicine. Whether in the form of microparticles, injectable hydrogels, rigid scaffolds, or bioinks, alginate provides a versatile platform for encapsulating cells and fostering an optimal environment to enhance cell viability. This review aims to highlight recent studies utilizing alginate in diverse formulations for cell transplantation, offering insights into its efficacy in treating various diseases and injuries within the field of regenerative medicine.

Visual Gustation via Regulable Elastic Photonic Crystals

The unique structural sensitivity of photonic crystals (PCs) endows them with stretchable or elastic tunability for light propagation and spontaneous emission modulation. Hydrogel PCs have been demonstrated to have biocompatibility and flexibility for potential human health detection and environmental security monitoring. However, current elastic PCs still possess a fixed elastic modulus and uncontrollable structural colors based on a tunable elastic modulus, posing considerable challenges for in situ detection, particularly in wearable or portable sensing devices. In this work, we introduced a novel chemo-mechanical transduction mechanism embedded within a photonic crystal nanomatrix, leading to the creation of structural colors and giving rise to a visual gustation sensing experience. By utilizing the captivating structural colors generated by the hydrogel PC, we employ abundant optical information to identify various analytes. The finite element analysis proved the electric field distribution in the PC matrix during stretch operations. The elastic-optical behaviors with various chemical cosolvents, including cations, anions, saccharides, or organic acids, were investigated. The mechanism of the Hofmeister effect regulating the elasticity of hydrogels was demonstrated with the network nanostructure of the hydrogels. The hydrogel PC matrix demonstrates remarkable capability in efficiently distinguishing a wide range of cations, anions, saccharides, and organic acids across various concentrations, mixtures, and even real food samples, such as tastes and soups. Through comprehensive research, a precise relationship between the structural colors and the elastic modulus of hydrogel PCs has been established, contributing to the biomatching elastic-optics platform for wearable devices, a dynamic environment, and clinical or health monitoring auxiliary.

In Vitro Modulation of Spontaneous Activity in Embryonic Cardiomyocytes Cultured on Poly(vinyl alcohol)/Bioglass Type 58S Electrospun Scaffolds

Because of the physiological and cardiac changes associated with cardiovascular disease, tissue engineering can potentially restore the biological functions of cardiac tissue through the fabrication of scaffolds. In the present study, hybrid nanofiber scaffolds of poly (vinyl alcohol) (PVA) and bioglass type 58S (58SiO2-33CaO-9P2O5, Bg) were fabricated, and their effect on the spontaneous activity of chick embryonic cardiomyocytes in vitro was determined. PVA/Bg nanofibers were produced by electrospinning and stabilized by chemical crosslinking with glutaraldehyde. The electrospun scaffolds were analyzed to determine their chemical structure, morphology, and thermal transitions. The crosslinked scaffolds were more stable to degradation in water. A Bg concentration of 25% in the hybrid scaffolds improved thermal stability and decreased degradation in water after PVA crosslinking. Cardiomyocytes showed increased adhesion and contractility in cells seeded on hybrid scaffolds with higher Bg concentrations. In addition, the effect of Ca2+ ions released from the bioglass on the contraction patterns of cultured cardiomyocytes was investigated. The results suggest that the scaffolds with 25% Bg led to a uniform beating frequency that resulted in synchronous contraction patterns.

A review of advanced hydrogels for cartilage tissue engineering

With the increase in weight and age of the population, the consumption of tobacco, inappropriate foods, and the reduction of sports activities in recent years, bone and joint diseases such as osteoarthritis (OA) have become more common in the world. From the past until now, various treatment strategies (e.g., microfracture treatment, Autologous Chondrocyte Implantation (ACI), and Mosaicplasty) have been investigated and studied for the prevention and treatment of this disease. However, these methods face problems such as being invasive, not fully repairing the tissue, and damaging the surrounding tissues. Tissue engineering, including cartilage tissue engineering, is one of the minimally invasive, innovative, and effective methods for the treatment and regeneration of damaged cartilage, which has attracted the attention of scientists in the fields of medicine and biomaterials engineering in the past several years. Hydrogels of different types with diverse properties have become desirable candidates for engineering and treating cartilage tissue. They can cover most of the shortcomings of other treatment methods and cause the least secondary damage to the patient. Besides using hydrogels as an ideal strategy, new drug delivery and treatment methods, such as targeted drug delivery and treatment through mechanical signaling, have been studied as interesting strategies. In this study, we review and discuss various types of hydrogels, biomaterials used for hydrogel manufacturing, cartilage-targeting drug delivery, and mechanosignaling as modern strategies for cartilage treatment.

Closer to The Heart: Harnessing the Power of Targeted Extracellular Vesicle Therapies

Extracellular vesicles (EVs) have emerged as novel diagnostic and therapeutic approaches for cardiovascular diseases. EVs derived from various origins exhibit distinct effects on the cardiovascular system. However, the application of native EVs is constrained due to their poor stabilities and limited targeting capabilities. Currently, targeted modification of EVs primarily involves genetic engineering, chemical modification (covalent, non-covalent), cell membrane modification, and biomaterial encapsulation. These techniques enhance the stability, biological activity, target-binding capacity, and controlled release of EVs at specific cells and tissues. The diverse origins of cardioprotective EVs are covered, and the applications of cardiac-targeting EV delivery systems in protecting against cardiovascular diseases are discussed. This review summarizes the current stage of research on the potential of EV-based targeted therapies for addressing cardiovascular disorders.

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

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

Development of Anticancer Ferric Complex Based on Human Serum Albumin Nanoparticles That Generate Oxygen in Cells to Overcome Hypoxia-Induced Resistance in Metal Chemotherapy

To achieve the remarkable therapeutic efficacy of a ferric (Fe) complex via a reactive oxygen species (ROS) mechanism in solid tumors, a therapeutic Fe-based Schiff-base complex (Fe1) was synthesized and encapsulated in human serum albumin (HSA) nanoparticles (NPs), which generated oxygen (O2) in cancer cells in situ. The HSA-Fe1-O2 NP (HSA-Fe1-O2NP) delivery system effectively overcame hypoxia-induced resistance in metal chemotherapy, alleviated the hypoxic condition of tumor tissues, and showed excellent tumor suppression by generating excess ROS and promoting the apoptosis of SK-N-MC tumor cells. The HSA-Fe1-O2NPs not only enhanced the ability of the Fe1 complex to target tumor cells but also decreased adverse effects in vivo.

Evaluation of Tyrosine Kinase Inhibitors Loaded Injectable Hydrogels for Improving Connexin43 Gap Junction Intercellular Communication

Myocardial infarction (MI) is one of the leading causes of death in the developed world, and the loss of cardiomyocytes plays a critical role in the pathogenesis of heart failure. Implicated in this process is a decrease in gap junction intercellular communication due to remodeling of Connexin43 (Cx43). We previously identified that intraperitoneal injection of the Pyk2 inhibitor PF4618433 reduced infarct size, maintained Cx43 at the intercalated disc in left ventricle hypertrophic myocytes, and improved cardiac function in an MI animal model of heart failure. With the emergence of injectable hydrogels as a therapeutic toward the regeneration of cardiac tissue after MI, here, we provide proof of concept that the release of tyrosine kinase inhibitors from hydrogels could have beneficial effects on cardiomyocytes. We developed an injectable hydrogel consisting of thiolated hyaluronic acid and P123-maleimide micelles that can incorporate PF4618433 as well as the Src inhibitor Saracatinib and achieved sustained release (of note, Src activates Pyk2). Using neonatal rat ventricular myocytes in the presence of a phorbol ester, endothelin-1, or phenylephrine to stimulate cardiac hypertrophy, the release of PF4618433 from the hydrogel had the same ability to decrease Cx43 tyrosine phosphorylation and maintain Cx43 localization at the plasma membrane as when directly added to the growth media. Additional beneficial effects included decreases in apoptosis, the hypertrophic marker atrial natriuretic peptide (ANP), and serine kinases upregulated in hypertrophy. Finally, the presence of both PF4618433 and Saracatinib further decreased the level of ANP and apoptosis than each inhibitor alone, suggesting that a combinatorial approach may be most beneficial. These findings provide the groundwork to test if tyrosine kinase inhibitor release from hydrogels will have a beneficial effect in an animal model of MI-induced heart failure.

Shaping the Future of Cardiovascular Disease by 3D Printing Applications in Stent Technology and its Clinical Outcomes

Cardiovascular disease (CVD) is a leading cause of death worldwide. In recent years, 3D printing technology has ushered in a new era of innovation in cardiovascular medicine. 3D printing in CVD management encompasses various aspects, from patient-specific models and preoperative planning to customized medical devices and novel therapeutic approaches. In-stent technology, 3D printing has revolutionized the design and fabrication of intravascular stents, offering tailored solutions for complex anatomies and individualized patient needs. The advantages of 3D-printed stents, such as improved biocompatibility, enhanced mechanical properties, and reduced risk of in-stent restenosis. Moreover, the clinical trials and case studies that shed light on the potential of 3D printing technology to improve patient outcomes and revolutionize the field has been comprehensively discussed. Furthermore, regulatory considerations, and challenges in implementing 3D-printed stents in clinical practice are also addressed, underscoring the need for standardization and quality assurance to ensure patient safety and device reliability. This review highlights a comprehensive resource for clinicians, researchers, and policymakers seeking to harness the full potential of 3D printing technology in the fight against CVD.

Research Progress on Cardiac Tissue Construction of Mesenchymal Stem Cells for Myocardial Infarction

Heart failure is still the main complication affecting the prognosis of acute myocardial infarction (AMI), and mesenchymal stem cells (MSCs) are an effective treatment to replace necrotic myocardium and improve cardiac functioning. However, the transplant survival rate of MSCs still presents challenges. In this review, the biological characteristics of MSCs, the progress of mechanism research in the treatment of myocardial infarction, and the advances in improving the transplant survival rate of MSCs in the replacement of necrotic myocardial infarction are systematically described. From a basic to advanced clinical research, MSC transplants have evolved from a pure injection, an exosome injection, the genetic modification of MSCs prior to injection to the cardiac tissue engineering of MSC patch grafting. This study shows that MSCs have wide clinical applications in the treatment of AMI, suggesting improved myocardial tissue creation. A broader clinical application prospect will be explored and developed to improve the survival rate of MSC transplants and myocardial vascularization.

Low-adhesion and low-swelling hydrogel based on alginate and carbonated water to prevent temporary dilation of wound sites

Hydrogel-based wound dressings have been developed for rapid wound healing; however, their adhesive properties have not been adequately investigated. Excessive adhesion to the skin causes wound expansion and pain when hydrogels absorb exudates and swell at wound sites. Herein, we developed a low-adhesion and low-swelling hydrogel dressing using alginate, which is non-adhesive to cells and skin tissue, CaCO3, and carbonated water. The alginate/CaCO3 solution rapidly formed a hydrogel upon the addition of carbonated water, and the CO2 in the hydrogel diffused into the atmosphere, preventing acidification and obtaining a pH value suitable for wound healing. Remarkably, the skin adhesion and swelling of the hydrogel were 11.9- to 16.5-fold and 1.9-fold lower, respectively, than those of clinical low-adhesion hydrogel dressings. In vivo wound-healing tests in mice demonstrated its therapeutic efficacy, and the prepared hydrogel prevented temporary wound dilation during early healing. These results illustrate the importance of controlling skin adhesion and swelling in wound dressings and demonstrate the potential clinical applications of this wound-friendly hydrogel dressing.

Smart alginate inks for tissue engineering applications

Amazing achievements have been made in the field of tissue engineering during the past decades. However, we have not yet seen fully functional human heart, liver, brain, or kidney tissue emerge from the clinics. The promise of tissue engineering is thus still not fully unleashed. This is mainly related to the challenges associated with producing tissue constructs with similar complexity as native tissue. Bioprinting is an innovative technology that has been used to obliterate these obstacles. Nevertheless, natural organs are highly dynamic and can change shape over time; this is part of their functional repertoire inside the body. 3D-bioprinted tissue constructs should likewise adapt to their surrounding environment and not remain static. For this reason, the new trend in the field is 4D bioprinting - a new method that delivers printed constructs that can evolve their shape and function over time. A key lack of methodology for printing approaches is the scalability, easy-to-print, and intelligent inks. Alginate plays a vital role in driving innovative progress in 3D and 4D bioprinting due to its exceptional properties, scalability, and versatility. Alginate's ability to support 3D and 4D printing methods positions it as a key material for fueling advancements in bioprinting across various applications, from tissue engineering to regenerative medicine and beyond. Here, we review the current progress in designing scalable alginate (Alg) bioinks for 3D and 4D bioprinting in a "dry"/air state. Our focus is primarily on tissue engineering, however, these next-generation materials could be used in the emerging fields of soft robotics, bioelectronics, and cyborganics.

Potent inhibition of MMP-9 by a novel sustained-release platform attenuates left ventricular remodeling following myocardial infarction

Sustained drug-release systems prolong the retention of therapeutic drugs within target tissues to alleviate the need for repeated drug administration. Two major caveats of the current systems are that the release rate and the timing cannot be predicted or fine-tuned because they rely on uncontrolled environmental conditions and that the system must be redesigned for each drug and treatment regime because the drug is bound via interactions that are specific to its structure and composition. We present a controlled and universal sustained drug-release system, which comprises minute spherical particles in which a therapeutic protein is affinity-bound to alginate sulfate (AlgS) through one or more short heparin-binding peptide (HBP) sequence repeats. Employing post-myocardial infarction (MI) heart remodeling as a case study, we show that the release of C9-a matrix metalloproteinase-9 (MMP-9) inhibitor protein that we easily bound to AlgS by adding one, two, or three HBP repeats to its sequence-can be directly controlled by modifying the number of HBP repeats. In an in vivo study, we directly injected AlgS particles, which were bound to C9 through three HBP repeats, into the left ventricular myocardium of mice following MI. We found that the particles substantially reduced post-MI remodeling, attesting to the sustained, local release of the drug within the tissue. As the number of HBP repeats controls the rate of drug release from the AlgS particles, and since C9 can be easily replaced with almost any protein, our tunable sustained-release system can readily accommodate a wide range of protein-based treatments.

Marine biomaterials in biomedical nano/micro-systems

Marine resources in unique marine environments provide abundant, cost-effective natural biomaterials with distinct structures, compositions, and biological activities compared to terrestrial species. These marine-derived raw materials, including polysaccharides, natural protein components, fatty acids, and marine minerals, etc., have shown great potential in preparing, stabilizing, or modifying multifunctional nano-/micro-systems and are widely applied in drug delivery, theragnostic, tissue engineering, etc. This review provides a comprehensive summary of the most current marine biomaterial-based nano-/micro-systems developed over the past three years, primarily focusing on therapeutic delivery studies and highlighting their potential to cure a variety of diseases. Specifically, we first provided a detailed introduction to the physicochemical characteristics and biological activities of natural marine biocomponents in their raw state. Furthermore, the assembly processes, potential functionalities of each building block, and a thorough evaluation of the pharmacokinetics and pharmacodynamics of advanced marine biomaterial-based systems and their effects on molecular pathophysiological processes were fully elucidated. Finally, a list of unresolved issues and pivotal challenges of marine-derived biomaterials applications, such as standardized distinction of raw materials, long-term biosafety in vivo, the feasibility of scale-up, etc., was presented. This review is expected to serve as a roadmap for fundamental research and facilitate the rational design of marine biomaterials for diverse emerging applications.

Current application and modification strategy of marine polysaccharides in tissue regeneration: A review

Marine polysaccharides (MPs) are exceptional bioactive materials that possess unique biochemical mechanisms and pharmacological stability, making them ideal for various tissue engineering applications. Certain MPs, including agarose, alginate, carrageenan, chitosan, and glucan have been successfully employed as biological scaffolds in animal studies. As carriers of signaling molecules, scaffolds can enhance the adhesion, growth, and differentiation of somatic cells, thereby significantly improving the tissue regeneration process. However, the biological benefits of pure MPs composite scaffold are limited. Therefore, physical, chemical, enzyme modification and other methods are employed to expand its efficacy. Chemically, the structural properties of MPs scaffolds can be altered through modifications to functional groups or molecular weight reduction, thereby enhancing their biological activities. Physically, MPs hydrogels and sponges emulate the natural extracellular matrix, creating a more conducive environment for tissue repair. The porosity and high permeability of MPs membranes and nanomaterials expedite wound healing. This review explores the distinctive properties and applications of select MPs in tissue regeneration, highlighting their structural versatility and biological applicability. Additionally, we provide a brief overview of common modification strategies employed for MP scaffolds. In conclusion, MPs have significant potential and are expected to be a novel regenerative material for tissue engineering.

Challenges and future scope of exosomes in the treatment of cardiovascular diseases

Exosomes are nanosized vesicles that carry biologically diverse molecules for intercellular communication. Researchers have been trying to engineer exosomes for therapeutic purposes by using different approaches to deliver biologically active molecules to the various target cells efficiently. Recent technological advances may allow the biodistribution and pharmacokinetics of exosomes to be modified to meet scientific needs with respect to specific diseases. However, it is essential to determine an exosome's optimal dosage and potential side effects before its clinical use. Significant breakthroughs have been made in recent decades concerning exosome labelling and imaging techniques. These tools provide in situ monitoring of exosome biodistribution and pharmacokinetics and pinpoint targetability. However, because exosomes are nanometres in size and vary significantly in contents, a deeper understanding is required to ensure accurate monitoring before they can be applied in clinical settings. Different research groups have established different approaches to elucidate the roles of exosomes and visualize their spatial properties. This review covers current and emerging strategies for in vivo and in vitro exosome imaging and tracking for potential studies.

Advances in biomaterial-based cardiac organoids

Cardiovascular disease (CVD) is one of the important causes of death worldwide. The incidence and mortality rates are increasing annually with the intensification of social aging. The efficacy of drug therapy is limited in individuals suffering from severe heart failure due to the inability of myocardial cells to undergo regeneration and the challenging nature of cardiac tissue repair following injury. Consequently, surgical transplantation stands as the most efficient approach for treatment. Nevertheless, the shortage of donors and the considerable number of heart failure patients worldwide, estimated at 26 million, results in an alarming treatment deficit, with only around 5000 heart transplants feasible annually. The existing major alternatives, such as mechanical or xenogeneic hearts, have significant flaws, such as high cost and rejection, and are challenging to implement for large-scale, long-term use. An organoid is a three-dimensional (3D) cell tissue that mimics the characteristics of an organ. The critical application has been rated in annual biotechnology by authoritative journals, such as Science and Cell. Related industries have achieved rapid growth in recent years. Based on this technology, cardiac organoids are expected to pave the way for viable heart repair and treatment and play an essential role in pathological research, drug screening, and other areas. This review centers on the examination of biomaterials employed in cardiac repair, strategies employed for the reconstruction of cardiac structure and function, clinical investigations pertaining to cardiac repair, and the prospective applications of cardiac organoids. From basic research to clinical practice, the current status, latest progress, challenges, and prospects of biomaterial-based cardiac repair are summarized and discussed, providing a reference for future exploration and development of cardiac regeneration strategies.

Recent Advances of Natural-Polymer-Based Hydrogels for Wound Antibacterial Therapeutics

Hydrogels have a three-dimensional network structure and high-water content, are similar in structure to the extracellular matrix, and are often used as wound dressings. Natural polymers have excellent biocompatibility and biodegradability and are commonly utilized to prepare hydrogels. Natural-polymer-based hydrogels can have excellent antibacterial and bioactive properties by loading antibacterial agents or being combined with therapeutics such as phototherapy, which has great advantages in the field of treatment of microbial infections. In the published reviews of hydrogels used in the treatment of infectious wounds, the common classification criteria of hydrogels include function, source of antibacterial properties, type of antibacterial agent, etc. However, there are few reviews on the classification of hydrogels based on raw materials, and the description of natural-polymer-based hydrogels is not comprehensive and detailed. In this paper, based on the principle of material classification, the characteristics of seven types of natural polymers that can be used to prepare hydrogels are discussed, respectively, and the application of natural-polymer-based hydrogels in the treatment of infectious wounds is described in detail. Finally, the research status, limitations, and prospects of natural-polymer-based hydrogels are briefly discussed.

Plant-Derived Biomaterials and Their Potential in Cardiac Tissue Repair

Cardiovascular disease remains the leading cause of mortality worldwide. The inability of cardiac tissue to regenerate after an infarction results in scar tissue formation, leading to cardiac dysfunction. Therefore, cardiac repair has always been a popular research topic. Recent advances in tissue engineering and regenerative medicine offer promising solutions combining stem cells and biomaterials to construct tissue substitutes that could have functions similar to healthy cardiac tissue. Among these biomaterials, plant-derived biomaterials show great promise in supporting cell growth due to their inherent biocompatibility, biodegradability, and mechanical stability. More importantly, plant-derived materials have reduced immunogenic properties compared to popular animal-derived materials (e.g., collagen and gelatin). In addition, they also offer improved wettability compared to synthetic materials. To date, limited literature is available to systemically summarize the progression of plant-derived biomaterials in cardiac tissue repair. Herein, this paper highlights the most common plant-derived biomaterials from both land and marine plants. The beneficial properties of these materials for tissue repair are further discussed. More importantly, the applications of plant-derived biomaterials in cardiac tissue engineering, including tissue-engineered scaffolds, bioink in 3D biofabrication, delivery vehicles, and bioactive molecules, are also summarized using the latest preclinical and clinical examples.

Algal Phycocolloids: Bioactivities and Pharmaceutical Applications

Seaweeds are abundant sources of diverse bioactive compounds with various properties and mechanisms of action. These compounds offer protective effects, high nutritional value, and numerous health benefits. Seaweeds are versatile natural sources of metabolites applicable in the production of healthy food, pharmaceuticals, cosmetics, and fertilizers. Their biological compounds make them promising sources for biotechnological applications. In nature, hydrocolloids are substances which form a gel in the presence of water. They are employed as gelling agents in food, coatings and dressings in pharmaceuticals, stabilizers in biotechnology, and ingredients in cosmetics. Seaweed hydrocolloids are identified in carrageenan, alginate, and agar. Carrageenan has gained significant attention in pharmaceutical formulations and exhibits diverse pharmaceutical properties. Incorporating carrageenan and natural polymers such as chitosan, starch, cellulose, chitin, and alginate. It holds promise for creating biodegradable materials with biomedical applications. Alginate, a natural polysaccharide, is highly valued for wound dressings due to its unique characteristics, including low toxicity, biodegradability, hydrogel formation, prevention of bacterial infections, and maintenance of a moist environment. Agar is widely used in the biomedical field. This review focuses on analysing the therapeutic applications of carrageenan, alginate, and agar based on research highlighting their potential in developing innovative drug delivery systems using seaweed phycocolloids.

A Review on the Applications of Natural Biodegradable Nano Polymers in Cardiac Tissue Engineering

As cardiac diseases, which mostly result in heart failure, are increasing rapidly worldwide, heart transplantation seems the only solution for saving lives. However, this practice is not always possible due to several reasons, such as scarcity of donors, rejection of organs from recipient bodies, or costly medical procedures. In the framework of nanotechnology, nanomaterials greatly contribute to the development of these cardiovascular scaffolds as they provide an easy regeneration of the tissues. Currently, functional nanofibers can be used in the production of stem cells and in the regeneration of cells and tissues. The small size of nanomaterials, however, leads to changes in their chemical and physical characteristics that could alter their interaction and exposure to stem cells with cells and tissues. This article aims to review the naturally occurring biodegradable nanomaterials that are used in cardiovascular tissue engineering for the development of cardiac patches, vessels, and tissues. Moreover, this article also provides an overview of cell sources used for cardiac tissue engineering, explains the anatomy and physiology of the human heart, and explores the regeneration of cardiac cells and the nanofabrication approaches used in cardiac tissue engineering as well as scaffolds.

Trail Formation Alleviates Excessive Adhesion and Maintains Efficient Neutrophil Migration

Migrating neutrophils are found to leave behind subcellular trails in vivo, but the underlying mechanisms remain unclear. Here, an in vitro cell migration test plus an in vivo observation was applied to monitor neutrophil migration on intercellular cell adhesion molecule-1 (ICAM-1) presenting surfaces. Results indicated that migrating neutrophils left behind long-lasting, chemokine-containing trails. Trail formation tended to alleviate excessive cell adhesion enhanced by the trans-binding antibody and maintain efficient cell migration, which was associated with differential instantaneous edge velocity between the cell front and rear. CD11a and CD11b worked differently in inducing trail formation with polarized distributions on the cell body and uropod. Trail release at the cell rear was attributed to membrane ripping, in which β2-integrin was disrupted from the cell membrane through myosin-mediated rear contraction and integrin-cytoskeleton dissociation, potentiating a specialized strategy of integrin loss and cell deadhesion to maintain efficient migration. Moreover, neutrophil trails left on the substrate served as immune forerunners to recruit dendritic cells. These results provided an insight in elucidating the mechanisms of neutrophil trail formation and deciphering the roles of trail formation in efficient neutrophil migration.

Microfluidic encapsulation of photosynthetic cyanobacteria in hydrogel microparticles augments oxygen delivery to rescue ischemic myocardium

Cardiovascular disease, primarily caused by coronary artery disease, is the leading cause of death in the United States. While standard clinical interventions have improved patient outcomes, mortality rates associated with eventual heart failure still represent a clinical challenge. Macrorevascularization techniques inadequately address the microvascular perfusion deficits that persist beyond primary and secondary interventions. In this work, we investigate a photosynthetic oxygen delivery system that rescues the myocardium following acute ischemia. Using a simple microfluidic system, we encapsulated Synechococcus elongatus into alginate hydrogel microparticles (HMPs), which photosynthetically deliver oxygen to ischemic tissue in the absence of blood flow. We demonstrate that HMPs improve the viability of S. elongatus during the injection process and allow for simple oxygen diffusion. Adult male Wistar rats (n = 45) underwent sham surgery, acute ischemia reperfusion surgery, or a chronic ischemia reperfusion surgery, followed by injection of phosphate buffered saline (PBS), S. elongatus suspended in PBS, HMPs, or S. elongatus encapsulated in HMPs. Treatment with S. elongatus-HMPs mitigated cellular apoptosis and improved left ventricular function. Thus, delivery of S. elongatus encapsulated in HMPs improves clinical translation by utilizing a minimally invasive delivery platform that improves S. elongatus viability and enhances the therapeutic benefit of a novel photosynthetic system for the treatment of myocardial ischemia.

Alginate-Based Biomaterials in Tissue Engineering and Regenerative Medicine

Today, with the salient advancements of modern and smart technologies related to tissue engineering and regenerative medicine (TE-RM), the use of sustainable and biodegradable materials with biocompatibility and cost-effective advantages have been investigated more than before. Alginate as a naturally occurring anionic polymer can be obtained from brown seaweed to develop a wide variety of composites for TE, drug delivery, wound healing, and cancer therapy. This sustainable and renewable biomaterial displays several fascinating properties such as high biocompatibility, low toxicity, cost-effectiveness, and mild gelation by inserting divalent cations (e.g., Ca2+). In this context, challenges still exist in relation to the low solubility and high viscosity of high-molecular weight alginate, high density of intra- and inter-molecular hydrogen bonding, polyelectrolyte nature of the aqueous solution, and a lack of suitable organic solvents. Herein, TE-RM applications of alginate-based materials are deliberated, focusing on current trends, important challenges, and future prospects.

Novel bilayer coating on gentamicin-loaded titanium nanotube for orthopedic implants applications

Fabricating a multifunctional orthopedic implant which prevents post-surgery infection is highly desirable in advanced materials applications. However, designing an antimicrobial implant, which simultaneously promotes a sustained drug release and satisfactory cell proliferation, remains a challenge. The current study presents a drug-loaded surface-modified titanium nanotube (TNT) implant with different surface chemistry which was developed to investigate the effect of surface coating on drug release, antimicrobial activity, and cell proliferation. Accordingly, sodium alginate and chitosan were coated on the surface of TNT implants with different coating orders through layer-by-layer assembly. The coatings' swelling ratio and degradation rate were around 613% and 75%, respectively. The drug release results showed that surface-coatings prolonged the releasing profile for about 4 weeks. Chitosan coated TNTs demonstrated greater inhibition zone at 16.33mm compared with the other samples where no inhibition zone was observed. However, chitosan and alginate coated TNTs exhibited smaller inhibition zones at 48.56mm and 43.28mm, respectively, compared to bare TNT, which can be attributed to the coatings preventing the antibiotic burst release. Higher viability of cultured osteoblast cells was observed for chitosan-coated TNT as the top layer compared to the bare TNT at 12.18%, indicating improved bioactivity of TNT implants when the chitosan has the most contact with cells. Coupled with the cell viability assay, molecular dynamics (MD) simulations were carried out by placing collagen and fibronectin near the considered substrates. In agreement with cell viability results, MD simulations also indicated that chitosan had the highest adsorption energy approximately 60Kcal/mol. In summary, the proposed bilayer chitosan-coated drug-loaded TNT implant with chitosan and sodium alginate coating as the top and the bottom layers, respectively, can be a potential candidate for orthopedic applications in the light of its bacterial biofilm prevention, better osteoconductivity, and providing an adequate drug release profile.

Chitosan-Based Scaffolds for the Treatment of Myocardial Infarction: A Systematic Review

Cardiovascular diseases (CVD), such as myocardial infarction (MI), constitute one of the world's leading causes of annual deaths. This cardiomyopathy generates a tissue scar with poor anatomical properties and cell necrosis that can lead to heart failure. Necrotic tissue repair is required through pharmaceutical or surgical treatments to avoid such loss, which has associated adverse collateral effects. However, to recover the infarcted myocardial tissue, biopolymer-based scaffolds are used as safer alternative treatments with fewer side effects due to their biocompatibility, chemical adaptability and biodegradability. For this reason, a systematic review of the literature from the last five years on the production and application of chitosan scaffolds for the reconstructive engineering of myocardial tissue was carried out. Seventy-five records were included for review using the "preferred reporting items for systematic reviews and meta-analyses" data collection strategy. It was observed that the chitosan scaffolds have a remarkable capacity for restoring the essential functions of the heart through the mimicry of its physiological environment and with a controlled porosity that allows for the exchange of nutrients, the improvement of the electrical conductivity and the stimulation of cell differentiation of the stem cells. In addition, the chitosan scaffolds can significantly improve angiogenesis in the infarcted tissue by stimulating the production of the glycoprotein receptors of the vascular endothelial growth factor (VEGF) family. Therefore, the possible mechanisms of action of the chitosan scaffolds on cardiomyocytes and stem cells were analyzed. For all the advantages observed, it is considered that the treatment of MI with the chitosan scaffolds is promising, showing multiple advantages within the regenerative therapies of CVD.

Alginate Oligosaccharides Prevent Dextran-Sulfate-Sodium-Induced Ulcerative Colitis via Enhancing Intestinal Barrier Function and Modulating Gut Microbiota

Alginate oligosaccharides are degradation products of alginate and have attracted increasing attention due to their versatile biological functions. In the present study, C57BL/6 mice were used to assess the ameliorative effects and mechanisms of guluronate oligosaccharides (GAOS), mannuronic oligosaccharides (MAOS), and heterozygous alginate oligosaccharides (HAOS), which are the three alginate oligosaccharides of dextran sulfate sodium (DSS)-induced ulcerative colitis. The study showed that alginate oligosaccharides alleviated pathological histological damage by slowing down weight loss, inhibiting colonic length shortening, and reducing disease activity index (DAI) and histopathological scores. Alginate oligosaccharides modulated the colonic inflammatory response by reducing colonic MPO levels and downregulating the expression of IL-6 and IL-1β. Alginate oligosaccharides reduced intestinal permeability and reversed intestinal barrier damage by increasing the number of goblet cells, decreasing LPS levels, downregulating Bax protein levels, upregulating Bcl-2 protein levels, and enhancing the expression of the E-cadherin. Furthermore, alginate oligosaccharides modulated the composition of the gut microbiota and restored the production of short-chain fatty acids (SCFAs), especially acetate and butyrate. In conclusion, our study provides a scientific basis for the role of alginate oligosaccharides in relieving ulcerative colitis.

Extracellular vesicles mediate biological information delivery: A double-edged sword in cardiac remodeling after myocardial infarction

Acute myocardial infarction (AMI) is a severe ischemic disease with high morbidity and mortality worldwide. Maladaptive cardiac remodeling is a series of abnormalities in cardiac structure and function that occurs following myocardial infarction (MI). The pathophysiology of this process can be separated into two distinct phases: the initial inflammatory response, and the subsequent longer-term scar revision that includes the regression of inflammation, neovascularization, and fibrotic scar formation. Extracellular vesicles are nano-sized lipid bilayer vesicles released into the extracellular environment by eukaryotic cells, containing bioinformatic transmitters which are essential mediators of intercellular communication. EVs of different cellular origins play an essential role in cardiac remodeling after myocardial infarction. In this review, we first introduce the pathophysiology of post-infarction cardiac remodeling, as well as the biogenesis, classification, delivery, and functions of EVs. Then, we explore the dual role of these small molecule transmitters delivered by EVs in post-infarction cardiac remodeling, including the double-edged sword of pro-and anti-inflammation, and pro-and anti-fibrosis, which is significant for post-infarction cardiac repair. Finally, we discuss the pharmacological and engineered targeting of EVs for promoting heart repair after MI, thus revealing the potential value of targeted modulation of EVs and its use as a drug delivery vehicle in the therapeutic process of post-infarction cardiac remodeling.

Biodegradable and Non-Biodegradable Biomaterials and Their Effect on Cell Differentiation

Biomaterials for tissue scaffolds are key components in modern tissue engineering and regenerative medicine. Targeted reconstructive therapies require a proper choice of biomaterial and an adequate choice of cells to be seeded on it. The introduction of stem cells, and the transdifferentiation procedures, into regenerative medicine opened a new era and created new challenges for modern biomaterials. They must not only fulfill the mechanical functions of a scaffold for implanted cells and represent the expected mechanical strength of the artificial tissue, but furthermore, they should also assure their survival and, if possible, affect their desired way of differentiation. This paper aims to review how modern biomaterials, including synthetic (i.e., polylactic acid, polyurethane, polyvinyl alcohol, polyethylene terephthalate, ceramics) and natural (i.e., silk fibroin, decellularized scaffolds), both non-biodegradable and biodegradable, could influence (tissue) stem cells fate, regulate and direct their differentiation into desired target somatic cells.

Oxidized sodium alginate crosslinked silk fibroin composite scaffold for skin tissue engineering

Engineering skin substitutes represent a prospective source of advanced therapy in repairing severe traumatic wounds. Sodium alginate (SA) and silk fibroin (SF) are natural biomaterials, which are widely used in tissue engineering and other fields because of their low price, high safety, and good biocompatibility. However, SA itself degrades slowly, its degradation mode is difficult to control, and the degradation products are difficult to remove from the body because of its high molecular weight. Therefore, the composite scaffolds were prepared by freeze-drying composite technology by using the Schiff base reaction between biocompatible SF and permeable oxidized sodium alginate (OSA). Sodium periodate was used as oxidant to modify SA. The results showed that higher oxidation degree of OSA could be obtained by increasing the proportion of oxidant, and the relative molecular weight of the oxidized products could also be reduced. The composite scaffolds were prepared by using sodium tetraborate as a crosslinking accelerator of the Schiff base reaction between OSA and SF. FT-IR confirmed that the Schiff base group appeared in the material. In vitro biodegradation experiments showed that the biodegradation of the composite scaffolds was controllable, and the cytocompatibility experiment showed that the composite scaffolds had good biocompatibility.

Three-Dimensional Bio-Printed Cardiac Patch for Sustained Delivery of Extracellular Vesicles from the Interface

Cardiac tissue engineering has emerged as a promising strategy to treat infarcted cardiac tissues by replacing the injured region with an ex vivo fabricated functional cardiac patch. Nevertheless, integration of the transplanted patch with the host tissue is still a burden, limiting its clinical application. Here, a bi-functional, 3D bio-printed cardiac patch (CP) design is proposed, composed of a cell-laden compartment at its core and an extracellular vesicle (EV)-laden compartment at its shell for better integration of the CP with the host tissue. Alginate-based bioink solutions were developed for each compartment and characterized rheologically, examined for printability and their effect on residing cells or EVs. The resulting 3D bio-printed CP was examined for its mechanical stiffness, showing an elastic modulus between 4-5 kPa at day 1 post-printing, suitable for transplantation. Affinity binding of EVs to alginate sulfate (AlgS) was validated, exhibiting dissociation constant values similar to those of EVs with heparin. The incorporation of AlgS-EVs complexes within the shell bioink sustained EV release from the CP, with 88% cumulative release compared with 92% without AlgS by day 4. AlgS also prolonged the release profile by an additional 2 days, lasting 11 days overall. This CP design comprises great potential at promoting more efficient patch assimilation with the host.

Chiral Hydrogel Accelerates Re-Epithelization in Chronic Wounds via Mechanoregulation

Chronic wounds, such as diabetic foot ulcers (DFU), are a serious clinical problem. It is a challenge for the conventional wound dressings to achieve the desirable therapeutic efficacy due to the lack of biomimetic structural environment for rapid re-epithelization. Inspired by the naturally existing chiral structures in skin, a novel amino acid-based chiral hydrogel dressing is developed, consisting of left-handed or right-handed helical fibers self-assembled by l/d-phenylalanine derivatives. Compared to the levorotatory chiral hydrogel (LH), the dextral chiral hydrogel (DH) shows the ability to enhance cell adhesion, proliferation, and migration, and strongly promotes diabetic wound healing and re-epithelialization with a drug-free mode. Interestingly, the dextral chiral hydrogel is able to actively increase adsorption of type I collagen and promote proliferation and migration of keratinocyte in an integrin and YAP-mediated manner. This study not only provides a novel strategy for treatment of chronic wounds by utilizing dextral chiral hydrogel dressings, but also unveils the molecular mechanism for effect of dextral chiral structures on the promoted proliferation of keratinocyte.

Alginate oligosaccharides increase boar semen quality by affecting gut microbiota and metabolites in blood and sperm

Alginate oligosaccharides (AOS), natural polymers from brown seaweeds (such as Laminaria japonica, Undaria pinnatifida, and Sargassum fusiforme), have been reported to possess many beneficial advantages for health. In the current study, after 9 weeks of dietary supplementation, AOS 10 mg/kg group (AOS 10) group increased boar sperm motility from 87.8% to 93.5%, p < 0.05. Moreover, AOS10 increased the relative abundances of Bifidobacterium, Coprococcus, Butyricicoccus (1.3–2.3-fold; p < 0.05) to increase the beneficial blood and sperm metabolites (1.2–1.6-fold; p < 0.05), and important sperm proteins such as gelsolin, Zn-alpha2 glycoprotein, Cation Channel Sperm-Associated Protein, outer dense fiber of sperm tails, etc. (1.5–2.2-fold; p < 0.05). AOS had a long-term beneficial advantage on boar semen quality by the increase in semen volume (175 vs. 160 ml/ejaculation, p < 0.05). AOS may be used as dietary additives for improving semen quality.

Alginate hydrogel cross-linked by Ca2+ to promote spinal cord neural stem/progenitor cell differentiation and functional recovery after a spinal cord injury

Alginate capillary hydrogels seeded with differentiated cells can fill the lesion cavity and promote axonal regeneration after grafting into the injured spinal cord. Neural stem/progenitor cells (NSPCs) can potentially repair the spinal cord; however, effects of alginate hydrogels (AHs) on NSPCs remain unknown. In this study, we fabricated AHs cross-linked by Ca²⁺ and seeded hydrogels with rat embryonic day 14 NSPCs. Immunocytochemistry and electron microscopy show that NSPCs survive, proliferate and differentiate into neurons in vitro within the capillaries. After transplantation into an acute T8 complete spinal cord transection site in adult rats, approximately one-third (38.3%) of grafted cells survive and differentiate into neurons (40.7%), astrocytes (26.6%) and oligodendrocytes (28.4%) at 8 weeks post-grafting. NSPCs promote the growth of host axons within the capillaries in a time-dependent manner. Host axons make synapse-like contacts with NSPC-derived neurons within the hydrogel channels, and graft-derived axons extend into the host white and gray matter making putative synapses. This is paralleled by improved electrophysiological conductivity across the lesion and partial hindlimb locomotor recovery.

Preparation, Physicochemical Characterization, and Antioxidant Activity of Naringin–Silk Fibroin–Alginate Microspheres and Application in Yogurt

Naringin is the major polyphenol in bitter orange peel with antioxidant property. However, its pH sensitivity, low solubility, and bitter taste limit its application in food. In this study, naringin–sodium alginate–silk fibroin microspheres were prepared by the ionic gel method. The loading capacity and encapsulation efficiency of naringin in microspheres were 13.2% and 77.6%, respectively. The morphology of microspheres was characterized by scanning electron microscopy. The X-ray diffractometry and differential scanning calorimetry results showed naringin was amorphous after encapsulation. Fourier-transform infrared spectroscopy and molecular docking analysis confirmed the intermolecular hydrogen bonds between naringin and sodium alginate. Naringin could release from the microspheres continuously under different pH conditions. Compared with free naringin, the 2,2-diphenyl-1-picrylhydrazyl scavenging activity and the stability of naringin microspheres were significantly improved. The application of naringin microspheres in yogurt indicated the precipitation of whey could be effectively reduced and the decline rate of pH was inhibited. The study suggested that naringin encapsulated microspheres were beneficial for improving the shelf life of this bioactive product as well as providing a new idea for functional yogurt.

Advances in Organ-on-a-Chip Materials and Devices

The organ-on-a-chip (OoC) paves a way for biomedical applications ranging from preclinical to clinical translational precision. The current trends in the in vitro modeling is to reduce the complexity of human organ anatomy to the fundamental cellular microanatomy as an alternative of recreating the entire cell milieu that allows systematic analysis of medicinal absorption of compounds, metabolism, and mechanistic investigation. The OoC devices accurately represent human physiology in vitro; however, it is vital to choose the correct chip materials. The potential chip materials include inorganic, elastomeric, thermoplastic, natural, and hybrid materials. Despite the fact that polydimethylsiloxane is the most commonly utilized polymer for OoC and microphysiological systems, substitute materials have been continuously developed for its advanced applications. The evaluation of human physiological status can help to demonstrate using noninvasive OoC materials in real-time procedures. Therefore, this Review examines the materials used for fabricating OoC devices, the application-oriented pros and cons, possessions for device fabrication and biocompatibility, as well as their potential for downstream biochemical surface alteration and commercialization. The convergence of emerging approaches, such as advanced materials, artificial intelligence, machine learning, three-dimensional (3D) bioprinting, and genomics, have the potential to perform OoC technology at next generation. Thus, OoC technologies provide easy and precise methodologies in cost-effective clinical monitoring and treatment using standardized protocols, at even personalized levels. Because of the inherent utilization of the integrated materials, employing the OoC with biomedical approaches will be a promising methodology in the healthcare industry.

Research Advances of Injectable Functional Hydrogel Materials in the Treatment of Myocardial Infarction

Myocardial infarction (MI) has become one of the serious diseases threatening human life and health. However, traditional treatment methods for MI have some limitations, such as irreversible myocardial necrosis and cardiac dysfunction. Fortunately, recent endeavors have shown that hydrogel materials can effectively prevent negative remodeling of the heart and improve the heart function and long-term prognosis of patients with MI due to their good biocompatibility, mechanical properties, and electrical conductivity. Therefore, this review aims to summarize the research progress of injectable hydrogel in the treatment of MI in recent years and to introduce the rational design of injectable hydrogels in myocardial repair. Finally, the potential challenges and perspectives of injectable hydrogel in this field will be discussed, in order to provide theoretical guidance for the development of new and effective treatment strategies for MI.

Autologous Skin Fibroblast-Based PLGA Nanoparticles for Treating Multiorgan Fibrosis

Fibrotic diseases remain a substantial health burden with few therapeutic approaches. A hallmark of fibrosis is the aberrant activation and accumulation of myofibroblasts, which is caused by excessive profibrotic cytokines. Conventional anticytokine therapies fail to undergo clinical trials, as simply blocking a single or several antifibrotic cytokines cannot abrogate the profibrotic microenvironment. Here, biomimetic nanoparticles based on autologous skin fibroblasts are customized as decoys to neutralize multiple fibroblast-targeted cytokines. By fusing the skin fibroblast membrane onto poly(lactic-co-glycolic) acid cores, these nanoparticles, termed fibroblast membrane-camouflaged nanoparticles (FNPs), are shown to effectively scavenge various profibrotic cytokines, including transforming growth factor-β, interleukin (IL)-11, IL-13, and IL-17, thereby modulating the profibrotic microenvironment. FNPs are sequentially prepared into multiple formulations for different administration routines. As a proof-of-concept, in three independent animal models with various organ fibrosis (lung fibrosis, liver fibrosis, and heart fibrosis), FNPs effectively reduce the accumulation of myofibroblasts, and the formation of fibrotic tissue, concomitantly restoring organ function and indicating that FNPs are a potential broad-spectrum therapy for fibrosis management.

Natural Biopolymers as Additional Tools for Cell Microencapsulation Applied to Cellular Therapy

One of the limitations in organ, tissue or cellular transplantations is graft rejection. To minimize or prevent this, recipients must make use of immunosuppressive drugs (IS) throughout their entire lives. However, its continuous use generally causes several side effects. Although some IS dose reductions and withdrawal strategies have been employed, many patients do not adapt to these protocols and must return to conventional IS use. Therefore, many studies have been carried out to offer treatments that may avoid IS administration in the long term. A promising strategy is cellular microencapsulation. The possibility of microencapsulating cells originates from the opportunity to use biomaterials that mimic the extracellular matrix. This matrix acts as a support for cell adhesion and the syntheses of new extracellular matrix self-components followed by cell growth and survival. Furthermore, by involving the cells in a polymeric matrix, the matrix acts as an immunoprotective barrier, protecting cells against the recipient’s immune system while still allowing essential cell survival molecules to diffuse bilaterally through the polymer matrix pores. In addition, this matrix can be associated with IS, thus diminishing systemic side effects. In this context, this review will address the natural biomaterials currently in use and their importance in cell therapy.