Human mesenchymal stem cells encapsulated-coacervated photoluminescent nanodots layered bioactive chitosan/collagen hydrogel matrices to indorse cardiac healing after acute myocardial infarction

Engineering functional electroconductive hydrogels for targeted therapy in myocardial infarction repair

Myocardial infarction (MI) is characterized by a paucity of cardiomyocyte regeneration, leading to significant morbidity and mortality. Contemporary therapeutic modalities, while mitigating ischemic effects, fail to reconstitute the impaired electromechanical coupling within the infracted myocardium. Emerging evidence supports the utility of electroconductive hydrogels (ECHs) in facilitating post-MI cardiac function recovery by restoring the conductive microenvironment of the infarcted tissue. This comprehensive review delineates the taxonomy of ECHs predicated on their constituent conductive materials. It also encapsulates prevailing research trends in ECH-mediated MI repair, encompassing innovative design paradigms and microenvironment-sensitive strategies. The review also provides a critical appraisal of various implantation techniques, underscored by a thorough examination of the attendant considerations. It elucidates the mechanistic underpinnings by which hydrogels exert salutary effects on myocardial repair, namely by augmenting mechanical and electrical integrity, exerting anti-inflammatory actions, fostering angiogenesis, and curtailing adverse remodeling processes. Furthermore, the review engages with the pressing challenge of optimizing ECH functionality to achieve superior reparative outcomes post-MI. The discourse concludes with an anticipatory perspective on the evolution of ECH scaffolds, advocating for a tailored approach that integrates multifaceted physicochemical properties to cater to the nuances of personalized medicine.

Injectable hyaluronic acid-based microcapsules loaded with human endometrial stem cells improves cardiac function after myocardial infarction

Therapeutic efficacy of human endometrial stem cells (hEnSCs) encapsulated in hyaluronic acid (HA)-based microcapsules for cardiac regeneration in a rat model of MI is investigated. Cell-enclosed microcapsules were made by loading hEnSCs within hydrogel membrane produced from modified HA possessing phenolic hydroxyl moieties (HA-Ph). The hEnSC-loaded HA-Ph microcapsules (≈150 μm) injected intramyocardially into the peri-infarct area post-MI. The encapsulated cells showed mechanical stability and >87 % cell viability with cellular aggregation in size of about 100 μm until 7 days of culture. Transthoracic echocardiography evaluation indicated a significant increase in ejection fraction in encapsulated cells, compared to the other groups. Histological investigation of fibrosis and scar area by Masson trichrome and hematoxylin and eosin (H&E) staining illustrated less fibrosis and scarring area in the encapsulated cell group compared with the other groups. Furthermore, the cell-laden microcapsules significantly enhance expression intensities of actin and troponin as well as vascular endothelial-specific marker, all of which promote cardiac functions and contribute to a better therapeutic effect than the free-cell injection group in a rat model of MI. Our findings demonstrated that both hEnSCs and specifically hEnSC-loaded HA-based hydrogel vehicle can provide a promising novel therapy for functional restoration in MI instances.

Recent Advances and Developments in Injectable Conductive Polymer Gels for Bioelectronics

Soft matter bioelectronics represents an emerging and interdisciplinary research frontier aiming to harness the synergy between biology and electronics for advanced diagnostic and healthcare applications. In this context, a whole family of soft gels have been recently developed with self-healing ability and tunable biological mimetic features to act as a tissue-like space bridging the interface between the electronic device and dynamic biological fluids and body tissues. This review article provides a comprehensive overview of electroactive polymer gels, formed by noncovalent intermolecular interactions and dynamic covalent bonds, as injectable electroactive gels, covering their synthesis, characterization, and applications. First, hydrogels crafted from conducting polymers (poly(3,4-ethylene-dioxythiophene) (PEDOT), polyaniline (PANi), and polypyrrole (PPy))-based networks which are connected through physical interactions (e.g., hydrogen bonding, π-π stacking, hydrophobic interactions) or dynamic covalent bonds (e.g., imine bonds, Schiff-base, borate ester bonds) are addressed. Injectable hydrogels involving hybrid networks of polymers with conductive nanomaterials (i.e., graphene oxide, carbon nanotubes, metallic nanoparticles, etc.) are also discussed. Besides, it also delves into recent advancements in injectable ionic liquid-integrated gels (iongels) and deep eutectic solvent-integrated gels (eutectogels), which present promising avenues for future research. Finally, the current applications and future prospects of injectable electroactive polymer gels in cutting-edge bioelectronic applications ranging from tissue engineering to biosensing are outlined.

Collagen-Based Nanoparticles as Drug Delivery System in Wound Healing Applications

Background

Conventional wound dressings often adhere to wounds and can cause secondary injury due to their lack of anti-inflammatory and antibacterial properties. In contrast, collagen-based nanoparticles (NPs) as drug delivery systems exhibit both biocompatibility and biodegradability, presenting a promising avenue for accelerating wound healing processes.

Aims of Study

This review aims to provide a comprehensive overview of the mechanisms involved in wound healing, description of the attributes of ideal wound dressings, understanding of wound healing efficacy of collagen, exploring NPs-mediated drug delivery mechanisms in wound therapy, detailing the synthesis and fabrication techniques of collagen-based NPs, and delineating the applications of various collagen-based NPs infused wound dressings on wound healing.

Methodology

This review synthesizes relevant literature from reputable databases such as Scopus, Science Direct, Google Scholar, and PubMed.

Results

A diverse array of collagen-based NPs, including nanopolymers, metal NPs, nanoemulsions, nanoliposomes, and nanofibers, demonstrate pronounced efficacy in promoting wound closure and tissue regeneration. The incorporation of collagen-based NPs has not only become an agent for the delivery of therapeutics but also actively contributes to the wound healing cascade.

Conclusion

In conclusion, In brief, the use of collagen-based NPs presents a compelling strategy for expediting wound healing processes.

Harnessing the potential of hydrogels for advanced therapeutic applications: current achievements and future directions

The applications of hydrogels have expanded significantly due to their versatile, highly tunable properties and breakthroughs in biomaterial technologies. In this review, we cover the major achievements and the potential of hydrogels in therapeutic applications, focusing primarily on two areas: emerging cell-based therapies and promising non-cell therapeutic modalities. Within the context of cell therapy, we discuss the capacity of hydrogels to overcome the existing translational challenges faced by mainstream cell therapy paradigms, provide a detailed discussion on the advantages and principal design considerations of hydrogels for boosting the efficacy of cell therapy, as well as list specific examples of their applications in different disease scenarios. We then explore the potential of hydrogels in drug delivery, physical intervention therapies, and other non-cell therapeutic areas (e.g., bioadhesives, artificial tissues, and biosensors), emphasizing their utility beyond mere delivery vehicles. Additionally, we complement our discussion on the latest progress and challenges in the clinical application of hydrogels and outline future research directions, particularly in terms of integration with advanced biomanufacturing technologies. This review aims to present a comprehensive view and critical insights into the design and selection of hydrogels for both cell therapy and non-cell therapies, tailored to meet the therapeutic requirements of diverse diseases and situations.

Alginate-Chitosan Biodegradable and Biocompatible Based Hydrogel for Breast Cancer Immunotherapy and Diagnosis: A Comprehensive Review

Breast cancer is the most common type of cancer and the second leading cause of cancer-related mortality in females. There are many side effects due to chemotherapy and traditional surgery, like fatigue, loss of appetite, skin irritation, and drug resistance to cancer cells. Immunotherapy has become a hopeful approach toward cancer treatment, generating long-lasting immune responses in malignant tumor patients. Recently, hydrogel has received more attention toward cancer therapy due to its specific characteristics, such as decreased toxicity, fewer side effects, and better biocompatibility drug delivery to the particular tumor location. Researchers globally reported various investigations on hydrogel research for tumor diagnosis. The hydrogel-based multilayer platform with controlled nanostructure has received more attention for its antitumor effect. Chitosan and alginate play a leading role in the formation of the cross-link in a hydrogel. Also, they help in the stability of the hydrogel. This review discusses the properties, preparation, biocompatibility, and bioavailability of various research and clinical approaches of the multipolymer hydrogel made of alginate and chitosan for breast cancer treatment. With a focus on cases of breast cancer and the recovery rate, there is a need to find out the role of hydrogel in drug delivery for breast cancer treatment.

Chondroitin sulfate/silk fibroin hydrogel incorporating graphene oxide quantum dots with photothermal-effect promotes type H vessel-related wound healing

Chronic wounds with bacterial infection present formidable clinical challenges. In this study, a versatile hydrogel dressing with antibacterial and angiogenic activity composite of silk fibroin (SF), chondroitin sulfate (CS), and graphene oxide quantum dots (GOQDs) is fabricated. GOQDs@SF/CS (GSC) hydrogel is rapidly formed through the enzyme catalytic action of horseradish peroxidase. With the incorporation of GOQDs both gelation speed and mechanical properties have been enhanced, and the photothermal characteristics of GOQDs in GSC hydrogel enabled bacterial killing through photothermal treatment (PTT) at ∼51 °C. In vitro studies show that the GSC hydrogels demonstrate excellent antibacterial performance and induce type H vessel differentiation of endothelial cells via the activated ERK1/2 signaling pathway and upregulated SLIT3 expression. In vivo results show that the hydrogel significantly promotes type H vessels formation, which is related to the collagen deposition, epithelialization and, ultimately, accelerates the regeneration of infected skin defects. Collectively, this multifunctional GSC hydrogel, with dual action of antibacterial efficacy and angiogenesis promotion, emerges as an innovative skin dressing with the potential for advancing in infected wound healing.

Chitosan alchemy: transforming tissue engineering and wound healing

Chitosan, a biopolymer acquired from chitin, has emerged as a versatile and favorable material in the domain of tissue engineering and wound healing. Its biocompatibility, biodegradability, and antimicrobial characteristics make it a suitable candidate for these applications. In tissue engineering, chitosan-based formulations have garnered substantial attention as they have the ability to mimic the extracellular matrix, furnishing an optimal microenvironment for cell adhesion, proliferation, and differentiation. In the realm of wound healing, chitosan-based dressings have revealed exceptional characteristics. They maintain a moist wound environment, expedite wound closure, and prevent infections. These formulations provide controlled release mechanisms, assuring sustained delivery of bioactive molecules to the wound area. Chitosan's immunomodulatory properties have also been investigated to govern the inflammatory reaction during wound healing, fostering a balanced healing procedure. In summary, recent progress in chitosan-based formulations portrays a substantial stride in tissue engineering and wound healing. These innovative approaches hold great promise for enhancing patient outcomes, diminishing healing times, and minimizing complications in clinical settings. Continued research and development in this field are anticipated to lead to even more sophisticated chitosan-based formulations for tissue repair and wound management. The integration of chitosan with emergent technologies emphasizes its potential as a cornerstone in the future of regenerative medicine and wound care. Initially, this review provides an outline of sources and unique properties of chitosan, followed by recent signs of progress in chitosan-based formulations for tissue engineering and wound healing, underscoring their potential and innovative strategies.

Research and application of hydrogel-encapsulated mesenchymal stem cells in the treatment of myocardial infarction

Myocardial infarction (MI) stands out as a highly lethal disease that poses a significant threat to global health. Worldwide, heart failure resulting from MI remains a leading cause of human mortality. Mesenchymal stem cell (MSC) therapy has emerged as a promising therapeutic approach, leveraging its intrinsic healing properties. Nevertheless, pervasive issues, including a low cell retention rate, suboptimal survival rate, and incomplete differentiation of MSCs, present formidable challenges for further research. The introduction and advancement of biomaterials have offered a novel avenue for the exploration of MSC therapy in MI, marking considerable progress thus far. Notably, hydrogels, among the representative biomaterials, have garnered extensive attention within the biomedical field. This review delves into recent advancements, specifically focusing on the application of hydrogels to augment MSC therapy for cardiac tissue regeneration in MI.

Chitosan-Polyethylene Glycol Inspired Polyelectrolyte Complex Hydrogel Templates Favoring NEO-Tissue Formation for Cardiac Tissue Engineering

Neo-tissue formation and host tissue regeneration determine the success of cardiac tissue engineering where functional hydrogel scaffolds act as cardiac (extracellular matrix) ECM mimic. Translationally, the hydrogel templates promoting neo-cardiac tissue formation are currently limited; however, they are highly demanding in cardiac tissue engineering. The current study focused on the development of a panel of four chitosan-based polyelectrolyte hydrogels as cardiac scaffolds facilitating neo-cardiac tissue formation to promote cardiac regeneration. Chitosan-PEG (CP), gelatin-chitosan-PEG (GCP), hyaluronic acid-chitosan-PEG (HACP), and combined CP (CoCP) polyelectrolyte hydrogels were engineered by solvent casting and assessed for physiochemical, thermal, electrical, biodegradable, mechanical, and biological properties. The CP, GCP, HACP, and CoCP hydrogels exhibited excellent porosity (4.24 ± 0.18, 13.089 ± 1.13, 12.53 ± 1.30 and 15.88 ± 1.10 for CP, GCP, HACP and CoCP, respectively), water profile, mechanical strength, and amphiphilicity suitable for cardiac tissue engineering. The hydrogels were hemocompatible as evident from the negligible hemolysis and RBC aggregation and increased adsorption of plasma albumin. The hydrogels were cytocompatible as evident from the increased viability by MTT (>94% for all the four hydrogels) assay and direct contact assay. Also, the hydrogels supported the adhesion, growth, spreading, and proliferation of H9c2 cells as unveiled by rhodamine staining. The hydrogels promoted neo-tissue formation that was proven using rat and swine myocardial tissue explant culture. Compared to GCP and CoCP, CP and HACP were superior owing to the cell viability, hemocompatibility, and conductance, resulting in the highest degree of cytoskeletal organization and neo-tissue formation. The physiochemical and biological performance of these hydrogels supported neo-cardiac tissue formation. Overall, the CP, GCP, HACP, and CoCP hydrogel systems promise novel translational opportunities in regenerative cardiology.

Graphene derivative based hydrogels in biomedical applications

Graphene and its derivatives are widely used in tissue-engineering scaffolds, especially in the form of hydrogels. This is due to their biocompatibility, electrical conductivity, high surface area, and physicochemical versatility. They are also used in tissue engineering. Tissue engineering is suitable for 3D printing applications, and 3D printing makes it possible to construct 3D structures from 2D graphene, which is a revolutionary technology with promising applications in tissue and organ engineering. In this review, the recent literature in which graphene and its derivatives have been used as the major components of hydrogels is summarized. The application of graphene and its derivative-based hydrogels in tissue engineering is described in detail from different perspectives.

Conductive hydrogels for tissue repair

Conductive hydrogels (CHs) combine the biomimetic properties of hydrogels with the physiological and electrochemical properties of conductive materials, and have attracted extensive attention in the past few years. In addition, CHs have high conductivity and electrochemical redox properties and can be used to detect electrical signals generated in biological systems and conduct electrical stimulation to regulate the activities and functions of cells including cell migration, cell proliferation, and cell differentiation. These properties give CHs unique advantages in tissue repair. However, the current review of CHs is mostly focused on their applications as biosensors. Therefore, this article reviewed the new progress of CHs in tissue repair including nerve tissue regeneration, muscle tissue regeneration, skin tissue regeneration and bone tissue regeneration in the past five years. We first introduced the design and synthesis of different types of CHs such as carbon-based CHs, conductive polymer-based CHs, metal-based CHs, ionic CHs, and composite CHs, and the types and mechanisms of tissue repair promoted by CHs including anti-bacterial, antioxidant and anti-inflammatory properties, stimulus response and intelligent delivery, real-time monitoring, and promoted cell proliferation and tissue repair related pathway activation, which provides a useful reference for further preparation of bio-safer and more efficient CHs used in tissue regeneration.

Chitosan-Based Biomaterials for Tissue Regeneration

Chitosan is a chitin-derived biopolymer that has shown great potential for tissue regeneration and controlled drug delivery. It has numerous qualities that make it attractive for biomedical applications such as biocompatibility, low toxicity, broad-spectrum antimicrobial activity, and many others. Importantly, chitosan can be fabricated into a variety of structures including nanoparticles, scaffolds, hydrogels, and membranes, which can be tailored to deliver a desirable outcome. Composite chitosan-based biomaterials have been demonstrated to stimulate in vivo regeneration and the repair of various tissues and organs, including but not limited to, bone, cartilage, dental, skin, nerve, cardiac, and other tissues. Specifically, de novo tissue formation, resident stem cell differentiation, and extracellular matrix reconstruction were observed in multiple preclinical models of different tissue injuries upon treatment with chitosan-based formulations. Moreover, chitosan structures have been proven to be efficient carriers for medications, genes, and bioactive compounds since they can maintain the sustained release of these therapeutics. In this review, we discuss the most recently published applications of chitosan-based biomaterials for different tissue and organ regeneration as well as the delivery of various therapeutics.

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.

Chitosan-Based Hydrogels for Bioelectronic Sensing: Recent Advances and Applications in Biomedicine and Food Safety

Due to the lack of efficient bioelectronic interfaces, the communication between biology and electronics has become a great challenge, especially in constructing bioelectronic sensing. As natural polysaccharide biomaterials, chitosan-based hydrogels exhibit the advantages of flexibility, biocompatibility, mechanical tunability, and stimuli sensitivity, and could serve as an excellent interface for bioelectronic sensors. Based on the fabrication approaches, interaction mechanisms, and bioelectronic communication modalities, this review divided chitosan-based hydrogels into four types, including electrode-based hydrogels, conductive materials conjugated hydrogels, ionically conductive hydrogels, and redox-based hydrogels. To introduce the enhanced performance of bioelectronic sensors, as a complementary alternative, the incorporation of nanoparticles and redox species in chitosan-based hydrogels was discussed. In addition, the multifunctional properties of chitosan-based composite hydrogels enable their applications in biomedicine (e.g., smart skin patches, wood healing, disease diagnosis) and food safety (e.g., electrochemical sensing, smart sensing, artificial bioelectronic tongue, fluorescence sensors, surface-enhanced Raman scattering). We believe that this review will shed light on the future development of chitosan-based biosensing hydrogels for micro-implantable devices and human-machine interactions, as well as potential applications in medicine, food, agriculture, and other fields.

Insight into Heart-Tailored Architectures of Hydrogel to Restore Cardiac Functions after Myocardial Infarction

With permanent heart muscle injury or death, myocardial infarction (MI) is complicated by inflammatory, proliferation and remodeling phases from both the early ischemic period and subsequent infarct expansion. Though in situ re-establishment of blood flow to the infarct zone and delays of the ventricular remodeling process are current treatment options of MI, they fail to address massive loss of viable cardiomyocytes while transplanting stem cells to regenerate heart is hindered by their poor retention in the infarct bed. Equipped with heart-specific mimicry and extracellular matrix (ECM)-like functionality on the network structure, hydrogels leveraging tissue-matching biomechanics and biocompatibility can mechanically constrain the infarct and act as localized transport of bioactive ingredients to refresh the dysfunctional heart under the constant cyclic stress. Given diverse characteristics of hydrogel including conductivity, anisotropy, adhesiveness, biodegradability, self-healing and mechanical properties driving local cardiac repair, we aim to investigate and conclude the dynamic balance between ordered architectures of hydrogels and the post-MI pathological milieu. Additionally, our review summarizes advantages of heart-tailored architectures of hydrogels in cardiac repair following MI. Finally, we propose challenges and prospects in clinical translation of hydrogels to draw theoretical guidance on cardiac repair and regeneration after MI.

Biomaterials-Based Cell Therapy for Myocardial Tissue Regeneration

Cardiovascular diseases (CVDs) have been the leading cause of death worldwide during the past several decades. Cell loss is the main problem that results in cardiac dysfunction and further mortality. Cell therapy aiming to replenish the lost cells is proposed to treat CVDs especially ischemic heart diseases which lead to a big portion of cell loss. Due to the direct injection's low cell retention and survival ratio, cell therapy using biomaterials as cell carriers has attracted more and more attention because of their promotion of cell delivery and maintenance at the aiming sites. In this review, the three main factors involved in cell therapy for myocardial tissue regeneration: cell sources (somatic cells, stem cells, and engineered cells), chemical components of cell carriers (natural materials, synthetic materials, and electroactive materials), and categories of cell delivery materials (patches, microspheres, injectable hydrogels, nanofiber and microneedles, etc.) are systematically summarized. An introduction of the methods including magnetic resonance/radionuclide/photoacoustic and fluorescence imaging for tracking the behavior of transplanted cells in vivo is also included. Current challenges of biomaterials-based cell therapy and their future directions are provided to give both beginners and professionals a clear view of the development and future trends in this area.

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.

Recent advances of 3D hydrogel culture systems for mesenchymal stem cell-based therapy and cell behavior regulation

Mesenchymal stem cells (MSCs) have been increasingly recognized as resources for disease treatments and regenerative medicine. Meanwhile, the unique chemical and physical properties of hydrogels provide innate advantages to achieve...

Chitosan as Functional Biomaterial for Designing Delivery Systems in Cardiac Therapies

Cardiovascular diseases are a leading cause of mortality across the globe, and transplant surgeries are not always successful since it is not always possible to replace most of the damaged heart tissues, for example in myocardial infarction. Chitosan, a natural polysaccharide, is an important biomaterial for many biomedical and pharmaceutical industries. Based on the origin, degree of deacetylation, structure, and biological functions, chitosan has emerged for vital tissue engineering applications. Recent studies reported that chitosan coupled with innovative technologies helped to load or deliver drugs or stem cells to repair the damaged heart tissue not just in a myocardial infarction but even in other cardiac therapies. Herein, we outlined the latest advances in cardiac tissue engineering mediated by chitosan overcoming the barriers in cardiac diseases. We reviewed in vitro and in vivo data reported dealing with drug delivery systems, scaffolds, or carriers fabricated using chitosan for stem cell therapy essential in cardiac tissue engineering. This comprehensive review also summarizes the properties of chitosan as a biomaterial substrate having sufficient mechanical stability that can stimulate the native collagen fibril structure for differentiating pluripotent stem cells and mesenchymal stem cells into cardiomyocytes for cardiac tissue engineering.

Collagen-based formulations for wound healing: A literature review

Wounds have always been the point of concern owing to the involvement of infections and the level of severity. Therefore, the management of wounds always requires additional effort for comprehensive healing and subsequent removal of the scar from the wound site. The role of biomaterials in the management of chronic wounds has been well established. One of such biomaterials is collagen (Col) that is considered to be the crucial component of most of the formulations being developed for wound healing. The role of Col extracted from marine invertebrates remains an unmarked origin of the proteinaceous constituent in the evolution of innovative pharmaceuticals. Col is a promising, immiscible, fibrous amino acid of indigenous origin that is ubiquitously present in extracellular matrices and connective tissues. There are different types of Col present in the body such as type I, II, III, IV, and V however the natural sources of Col are vegetables and marine animals. Its physical properties like high tensile strength, adherence nature, elasticity, and remodeling contribute significantly in the wound healing process. Col containing formulations such as hydrogels, sponges, creams, peptides, and composite nanofibers have been utilized widely in wound healing and tissue engineering purposes truly as the first line of defense. Here we present the recent advancements in Col based dosage forms for wound healing. The Col based market of topical preparations and the published reports identify Colas a useful biomaterial for the delivery of pharmaceuticals and a platform for tissue engineering.

Cardiac fibrosis: Myofibroblast-mediated pathological regulation and drug delivery strategies

Cardiac fibrosis remains an unresolved problem in heart diseases. After initial injury, cardiac fibroblasts (CFs) are activated and subsequently differentiate into myofibroblasts (myoFbs) that are major mediator cells in the pathological remodeling. MyoFbs exhibit proliferative and secretive characteristics, and contribute to extracellular matrix (ECM) turnover, collagen deposition. The persistent functions of myoFbs lead to fibrotic scars and cardiac dysfunction. The anti-fibrotic treatment is hindered by the elusive mechanism of fibrosis and lack of specific targets on myoFbs. In this review, we will outline the progress of cardiac fibrosis and its contributions to the heart failure. We will also shed light on the role of myoFbs in the regulation of adverse remodeling. The communication between myoFbs and other cells that are involved in the heart injury and repair respectively will be reviewed in detail. Then, recently developed therapeutic strategies to treat fibrosis will be summarized such as i) chimeric antigen receptor T cell (CAR-T) therapy with an optimal target on myoFbs, ii) direct reprogramming from stem cells to quiescent CFs, iii) "off-target" small molecular drugs. The application of nano/micro technology will be discussed as well, which is involved in the construction of cell-based biomimic platforms and "pleiotropic" drug delivery systems.

Cutting-edge progress and challenges in stimuli responsive hydrogel microenvironment for success in tissue engineering today

The field of tissue engineering has numerous potential for modified therapeutic results and has been inspired by enhancements in bioengineering at the recent decades. The techniques of regenerating tissues and assembling functional paradigms that are responsible for repairing, maintaining, and revitalizing lost organs and tissues have affected the entire spectrum of health care studies. Strategies to combine bioactive molecules, biocompatible materials and cells are important for progressing the renewal of damaged tissues. Hydrogels have been utilized as one of the most popular cell substrate/carrier in tissue engineering since previous decades, respect to their potential to retain a 3D structure, to protect the embedded cells, and to mimic the native ECM. The hydrophilic nature of hydrogels can provide an ideal milieu for cell viability and structure, which simulate the native tissues. Hydrogel systems have been applied as a favorable matrix for growth factor delivery and cell immobilization. This study reviews a brief explanation of the structure, characters, applications, fabrication methods, and future outlooks of stimuli responsive hydrogels in tissue engineering and, in particular, 3D bioprinting.

Advances and trends of hydrogel therapy platform in localized tumor treatment: A review

Due to limitations of treatment and the stubbornness of infiltrative tumor cells, the outcome of conventional antitumor treatment is often compromised by a variety of factors, including severe side effects, unexpected recurrence, and massive tissue loss during the treatment. Hydrogel-based therapy is becoming a promising option of cancer treatment, because of its controllability, biocompatibility, high drug loading, prolonged drug release, and specific stimuli-sensitivity. Hydrogel-based therapy has good malleability and can reach some areas that cannot be easily touched by surgeons. Furthermore, hydrogel can be used not only as a carrier for tumor treatment agents, but also as a scaffold for tissue repair. In this review, we presented the latest researches in hydrogel applications of localized tumor therapy and highlighted the recent progress of hydrogel-based therapy in preventing postoperative tumor recurrence and improving tissue repair, thus proposing a new trend of hydrogel-based technology in localized tumor therapy. And this review aims to provide a novel reference and inspire thoughts for a more accurate and individualized cancer treatment.