Self-healing hydrogel as an injectable implant: translation in brain diseases

Enhancing regenerative medicine with self-healing hydrogels: A solution for tissue repair and advanced cyborganic healthcare devices

Considering the global burden related to tissue and organ injuries or failures, self-healing hydrogels may be an attractive therapeutic alternative for the future. Self-healing hydrogels are highly hydrated 3D structures with the ability to self-heal after breaking, this property is attributable to a variety of dynamic non-covalent and covalent bonds that are able to re-linking within the matrix. Self-healing ability specially benefits minimal invasive medical treatments with cell-delivery support. Moreover, those tissue-engineered self-healing hydrogels network have demonstrated effectiveness for myriad purposes; for instance, they could act as delivery-platforms for different cargos (drugs, growth factors, cells, among others) in tissues such as bone, cartilage, nerve or skin. Besides, self-healing hydrogels have currently found their way into new and novel applications; for example, with the development of the self-healing adhesive hydrogels, by merely aiding surgical closing processes and by providing biomaterial-tissue adhesion. Furthermore, conductive hydrogels permit the stimuli and monitoring of natural electrical signals, which facilitated a better fitting of hydrogels in native tissue or the diagnosis of various health diseases. Lastly, self-healing hydrogels could be part of cyborganics - a merge between biology and machinery - which can pave the way to a finer healthcare devices for diagnostics and precision therapies.

Exploring the properties and potential of the neural extracellular matrix for next-generation regenerative therapies

The extracellular matrix (ECM) is a dynamic and complex network of proteins and molecules that surrounds cells and tissues in the nervous system and orchestrates a myriad of biological functions. This review carefully examines the diverse interactions between cells and the ECM, as well as the transformative chemical and physical changes that the ECM undergoes during neural development, aging, and disease. These transformations play a pivotal role in shaping tissue morphogenesis and neural activity, thereby influencing the functionality of the central nervous system (CNS). In our comprehensive review, we describe the diverse behaviors of the CNS ECM in different physiological and pathological scenarios and explore the unique properties that make ECM-based strategies attractive for CNS repair and regeneration. Addressing the challenges of scalability, variability, and integration with host tissues, we review how advanced natural, synthetic, and combinatorial matrix approaches enhance biocompatibility, mechanical properties, and functional recovery. Overall, this review highlights the potential of decellularized ECM as a powerful tool for CNS modeling and regenerative purposes and sets the stage for future research in this exciting field. This article is categorized under: Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease Implantable Materials and Surgical Technologies > Nanomaterials and Implants.

Strongly Adhesive, Self-Healing, Hemostatic Hydrogel for the Repair of Traumatic Brain Injury

With wide clinical demands, therapies for traumatic brain injury (TBI) are a major problem in surgical procedures and after major trauma. Due to the difficulty in regeneration of neurons or axons after injury, as well as the inhibition of blood vessel growth by the formation of neural scars, existing treatment measures have limited effectiveness in repairing brain tissue. Herein, the biomultifunctional hydrogels are developed for TBI treatment based on the Schiff base reaction of calcium ion (Ca2+)-cross-linked oxidized sodium alginate (OSA) and carboxymethyl chitosan (CMCS). The obtained COCS hydrogel exhibits excellent adhesion to wet tissues, self-repair capability, and antimicrobial properties. What's particularly interesting is that the addition of Ca2+ increases the hydrogel's extensibility, enhancing its hemostatic capabilities. Biological assessments indicate that the COCS hydrogel demonstrates excellent biocompatibility, hemostatic properties, and the ability to promote arterial vessel repair. Importantly, the COCS hydrogel promotes the growth of cerebral microvessels by upregulating CD31, accelerates the proliferation of astrocytes, enhances the expression of GFAP, and stimulates the expression of neuron-specific markers such as NEUN and β-tubulin. All of these findings highlight that the strongly adhesive, self-healing, hemostatic hydrogel shows great potential for the repair of traumatic brain injury and other tissue repair therapy.

Remodelers of the vascular microenvironment: The effect of biopolymeric hydrogels on vascular diseases

Vascular disease is the leading health problem worldwide. Vascular microenvironment encompasses diverse cell types, including those within the vascular wall, blood cells, stromal cells, and immune cells. Initiation of the inflammatory state of the vascular microenvironment and changes in its mechanics can profoundly affect vascular homeostasis. Biomedical materials play a crucial role in modern medicine, hydrogels, characterized by their high-water content, have been increasingly utilized as a three-dimensional interaction network. In recent times, the remarkable progress in utilizing hydrogels and understanding vascular microenvironment have enabled the treatment of vascular diseases. In this review, we give an emphasis on the utilization of hydrogels and their advantages in the various vascular diseases including atherosclerosis, aneurysm, vascular ulcers of the lower limbs and myocardial infarction. Further, we highlight the importance and advantages of hydrogels as artificial microenvironments.

Advancements in Regenerative Hydrogels in Skin Wound Treatment: A Comprehensive Review

This state-of-the-art review explores the emerging field of regenerative hydrogels and their profound impact on the treatment of skin wounds. Regenerative hydrogels, composed mainly of water-absorbing polymers, have garnered attention in wound healing, particularly for skin wounds. Their unique properties make them well suited for tissue regeneration. Notable benefits include excellent water retention, creating a crucially moist wound environment for optimal healing, and facilitating cell migration, and proliferation. Biocompatibility is a key feature, minimizing adverse reactions and promoting the natural healing process. Acting as a supportive scaffold for cell growth, hydrogels mimic the extracellular matrix, aiding the attachment and proliferation of cells like fibroblasts and keratinocytes. Engineered for controlled drug release, hydrogels enhance wound healing by promoting angiogenesis, reducing inflammation, and preventing infection. The demonstrated acceleration of the wound healing process, particularly beneficial for chronic or impaired healing wounds, adds to their appeal. Easy application and conformity to various wound shapes make hydrogels practical, including in irregular or challenging areas. Scar minimization through tissue regeneration is crucial, especially in cosmetic and functional regions. Hydrogels contribute to pain management by creating a protective barrier, reducing friction, and fostering a soothing environment. Some hydrogels, with inherent antimicrobial properties, aid in infection prevention, which is a crucial aspect of successful wound healing. Their flexibility and ability to conform to wound contours ensure optimal tissue contact, enhancing overall treatment effectiveness. In summary, regenerative hydrogels present a promising approach for improving skin wound healing outcomes across diverse clinical scenarios. This review provides a comprehensive analysis of the benefits, mechanisms, and challenges associated with the use of regenerative hydrogels in the treatment of skin wounds. In this review, the authors likely delve into the application of rational design principles to enhance the efficacy and performance of hydrogels in promoting wound healing. Through an exploration of various methodologies and approaches, this paper is poised to highlight how these principles have been instrumental in refining the design of hydrogels, potentially revolutionizing their therapeutic potential in addressing skin wounds. By synthesizing current knowledge and highlighting potential avenues for future research, this review aims to contribute to the advancement of regenerative medicine and ultimately improve clinical outcomes for patients with skin wounds.

Injectable Hydrogels for Nervous Tissue Repair-A Brief Review

The repair of nervous tissue is a critical research field in tissue engineering because of the degenerative process in the injured nervous system. In this review, we summarize the progress of injectable hydrogels using in vitro and in vivo studies for the regeneration and repair of nervous tissue. Traditional treatments have not been favorable for patients, as they are invasive and inefficient; therefore, injectable hydrogels are promising for the treatment of damaged tissue. This review will contribute to a better understanding of injectable hydrogels as potential scaffolds and drug delivery system for neural tissue engineering applications.

Recent advances of hydrogels as smart dressings for diabetic wounds

Chronic diabetic wounds have been an urgent clinical problem, and wound dressings play an important role in their management. Due to the design of traditional dressings, it is difficult to achieve adaptive adhesion and on-demand removal of complex diabetic wounds, real-time monitoring of wound status, and dynamic adjustment of drug release behavior according to the wound microenvironment. Smart hydrogels, as smart dressings, can respond to environmental stimuli and achieve more precise local treatment. Here, we review the latest progress of smart hydrogels in wound bandaging, dynamic monitoring, and drug delivery for treatment of diabetic wounds. It is worth noting that we have summarized the most important properties of smart hydrogels for diabetic wound healing. In addition, we discuss the unresolved challenges and future prospects in this field. We hope that this review will contribute to furthering progress on smart hydrogels as improved dressing for diabetic wound healing and practical clinical application.

Melatonin-loaded self-healing hydrogel targets mitochondrial energy metabolism and promotes annulus fibrosus regeneration

Intervertebral disc (IVD) herniation is a major cause of chronic low back pain and disability. The current nucleus pulposus (NP) discectomy effectively relieves pain symptoms, but the annulus fibrosus (AF) defects are left unrepaired. Tissue engineering approaches show promise in treating AF injury and IVD degeneration; however, the presence of an inflammatory milieu at the injury site hinders the mitochondrial energy metabolism of AF cells, resulting in a lack of AF regeneration. In this study, we fabricated a dynamic self-healing hydrogel loaded with melatonin (an endocrine hormone well-known for its antioxidant and anti-inflammatory properties) and investigate whether melatonin-loaded hydrogel could promote AF defect repair by rescuing the matrix synthesis and energy metabolism of AF cells. The protective effects of melatonin on matrix components (e.g. type I and II collagen and aggrecan) in AF cells were observed in the presence of interleukin (IL)-1β. Additionally, melatonin was found to activate the nuclear factor erythroid 2-related factor signaling pathway, thereby safeguarding the mitochondrial function of AF cells from IL-1β, as evidenced by the increased level of adenosine triphosphate, mitochondrial membrane potential, and respiratory chain factor expression. The incorporation of melatonin into a self-healing hydrogel based on thiolated gelatin and β-cyclodextrin was proposed as a means of promoting AF regeneration. The successful implantation of melatonin-loaded hydrogel has been shown to facilitate in situ regeneration of AF tissue, thereby impeding IVD degeneration by preserving the hydration of nucleus pulposus in a rat box-cut IVD defect model. These findings offer compelling evidence that the development of a melatonin-loaded dynamic self-healing hydrogel can promote the mitochondrial functions of AF cells and represents a promising strategy for IVD regeneration.

Potential injectable hydrogels as biomaterials for central nervous system injury: A narrative review

Numerous modalities exist through which the central nervous system (CNS) may sustain injury or impairment, encompassing traumatic incidents, stroke occurrences, and neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. Presently available pharmacological and therapeutic interventions are incapable of restoring or regenerating damaged CNS tissue, leading to substantial unmet clinical needs among patients with CNS ailments or injuries. To address and facilitate the recovery of the impaired CNS, cell-based repair strategies encompass multiple mechanisms, such as neuronal replacement, therapeutic factor secretion, and the promotion of host brain plasticity. Despite the progression of cell-based CNS reparation as a therapeutic strategy throughout the years, substantial barriers have impeded its widespread implementation in clinical settings. The integration of cell technologies with advancements in regenerative medicine utilizing biomaterials and tissue engineering has recently facilitated the surmounting of several of these impediments. This comprehensive review presents an overview of distinct CNS conditions necessitating cell reparation, in addition to exploring potential biomaterial methodologies that enhance the efficacy of treating brain injuries.

Novel Approaches to the Establishment of Local Microenvironment from Resorbable Biomaterials in the Brain In Vitro Models

The development of brain in vitro models requires the application of novel biocompatible materials and biopolymers as scaffolds for controllable and effective cell growth and functioning. The "ideal" brain in vitro model should demonstrate the principal features of brain plasticity like synaptic transmission and remodeling, neurogenesis and angiogenesis, and changes in the metabolism associated with the establishment of new intercellular connections. Therefore, the extracellular scaffolds that are helpful in the establishment and maintenance of local microenvironments supporting brain plasticity mechanisms are of critical importance. In this review, we will focus on some carbohydrate metabolites-lactate, pyruvate, oxaloacetate, malate-that greatly contribute to the regulation of cell-to-cell communications and metabolic plasticity of brain cells and on some resorbable biopolymers that may reproduce the local microenvironment enriched in particular cell metabolites.

Pomegranate Polyphenol-Derived Injectable Therapeutic Hydrogels to Enhance Neuronal Regeneration

Drug delivery for the treatment of neurological disorders has long been considered complex due to difficulties in ensuring the drug targeting on a specific site of the damaged neural tissues and its prolonged release. A syringe-injectable polymeric hydrogel with mechanical moduli matching those of brain tissues can provide a solution to deliver the drugs to the specific region through intracranial injections in a minimally invasive manner. In this study, an injectable therapeutic hydrogel with antioxidant pomegranate polyphenols, punicalagin, is reported for efficient neuronal repair. The hydrogels composed of tyramine-functionalized hyaluronic acid and collagen crosslinked by enzymatic reactions have great injectability with high shape fidelity and effectively encapsulate the polyphenol therapeutics. Furthermore, the punicalagin continuously released from the hydrogels over several days could enhance the growth and differentiation of the neurons. Our findings for efficacy of the polyphenol therapeutic-encapsulated injectable hydrogels on neuronal regeneration would be promising for designing a new type of antioxidative biomaterials in brain disorder therapy.