Novel Temperature-Sensitive Hydrogel Promotes Wound Healing Through YAP and MEK-Mediated Mechanosensitivity

Chitosan/rutin multifunctional hydrogel with tunable adhesion, anti-inflammatory and antibacterial properties for skin wound healing

Effective wound care remains a significant challenge due to the need for infection prevention, inflammation reduction, and minimal tissue damage during dressing changes. To tackle these issues, we have developed a multifunctional hydrogel (CHI/CPBA/RU), composed of chitosan (CHI) modified with 4-carboxyphenylboronic acid (CPBA) and the natural flavonoid, rutin (RU). This design endows the hydrogel with body temperature-responsive adhesion and low temperature-triggered detachment, thus enabling painless removal during dressing changes. The CHI/CPBA/RU hydrogels exhibit excellent biocompatibility, maintaining over 97 % viability of L929 cells. They also demonstrate potent intracellular free radical scavenging activity, with scavenging ratios ranging from 53 % to 70 %. Additionally, these hydrogels show anti-inflammatory effects by inhibiting pro-inflammatory cytokines (TNF-α, IL-6, and iNOS) and increasing anti-inflammatory markers (Arg1 and CD206) in RAW 264.7 macrophages. Notably, they possess robust antimicrobial properties, inhibiting over 99.9 % of the growth of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus growth. In vivo testing on a murine full-thickness skin defect model shows that the hydrogel significantly accelerates wound healing by reducing inflammation, increasing collagen deposition, and promoting angiogenesis, achieving 98 % healing by day 10 compared to 78 % in the control group. These attributes make the polysaccharide-based hydrogel a promising material for advanced wound care.

Novel Functional Dressing Materials for Intraoral Wound Care

Intraoral wounds represent a particularly challenging category of mucosal and hard tissue injuries, characterized by the unique structures, complex environment, and distinctive healing processes within the oral cavity. They have a common occurrence yet frequently inflict significant inconvenience and pain on patients, causing a serious decline in the quality of life. A variety of novel functional dressings specifically designed for the moist and dynamic oral environment have been developed and realized accelerated and improved wound healing. Thoroughly analyzing and summarizing these materials is of paramount importance in enhancing the understanding and proficiently managing intraoral wounds. In this review, the particular processes and unique characteristics of intraoral wound healing are firstly described. Up-to-date knowledge of various forms, properties, and applications of existing products are then intensively discussed, which are categorized into animal products, plant extracts, natural polymers, and synthetic products. To conclude, this review presents a comprehensive framework of currently available functional intraoral wound dressings, with an aim to provoke inspiration of future studies to design more convenient and versatile materials.

3D Bioprinting of Artificial Skin Substitute with Improved Mechanical Property and Regulated Cell Behavior through Integrating Patterned Nanofibrous Films

Three-dimensional (3D) bioprinting has advantages for constructing artificial skin tissues in replicating the structures and functions of native skin. Although many studies have presented improved effect of printing skin substitutes in wound healing, using hydrogel inks to fabricate 3D bioprinting architectures with complicated structures, mimicking mechanical properties, and appropriate cellular environments is still challenging. Inspired by collagen nanofibers withstanding stress and regulating cell behavior, a patterned nanofibrous film was introduced to the printed hydrogel scaffold to fabricate a composite artificial skin substitute (CASS). The artificial dermis was printed using gelatin-hyaluronan hybrid hydrogels containing human dermal fibroblasts with gradient porosity and integrated with patterned nanofibrous films simultaneously, while the artificial epidermis was formed by seeding human keratinocytes upon the dermis. The collagen-mimicking nanofibrous film effectively improved the tensile strength and fracture resistance of the CASS, making it sewable for firm implantation into skin defects. Meanwhile, the patterned nanofibrous film also provided the biological cues to guide cell behavior. Consequently, CASS could effectively accelerate the regeneration of large-area skin defects in mouse and pig models by promoting re-epithelialization and collagen deposition. This research developed an effective strategy to prepare composite bioprinting architectures for enhancing mechanical property and regulating cell behavior, and CASS could be a promising skin substitute for treating large-area skin defects.

The roles of Hippo/YAP signaling pathway in physical therapy

Cellular behavior is regulated by mechanical signals within the cellular microenvironment. Additionally, changes of temperature, blood flow, and muscle contraction also affect cellular state and the development of diseases. In clinical practice, physical therapy techniques such as ultrasound, vibration, exercise, cold therapy, and hyperthermia are commonly employed to alleviate pain and treat diseases. However, the molecular mechanism about how these physiotherapy methods stimulate local tissues and control gene expression remains unknow. Fortunately, the discovery of YAP filled this gap, which has been reported has the ability to sense and convert a wide variety of mechanical signals into cell-specific programs for transcription, thereby offering a fresh perspective on the mechanisms by which physiotherapy treat different diseases. This review examines the involvement of Hippo/YAP signaling pathway in various diseases and its role in different physical therapy approaches on diseases. Furthermore, we explore the potential therapeutic implications of the Hippo/YAP signaling pathway and address the limitations and controversies surrounding its application in physiotherapy.

Emerging trends in the application of hydrogel-based biomaterials for enhanced wound healing: A literature review

Currently, there is a rising global incidence of diverse acute and chronic wounds, underscoring the immediate necessity for research and treatment advancements in wound repair. Hydrogels have emerged as promising materials for wound healing due to their unique physical and chemical properties. This review explores the classification and characteristics of hydrogel dressings, innovative preparation strategies, and advancements in delivering and releasing bioactive substances. Furthermore, it delves into the functional applications of hydrogels in wound healing, encompassing areas such as infection prevention, rapid hemostasis and adhesion adaptation, inflammation control and immune regulation, granulation tissue formation, re-epithelialization, and scar prevention and treatment. The mechanisms of action of various functional hydrogels are also discussed. Finally, this article also addresses the current limitations of hydrogels and provides insights into their potential future applications and upcoming innovative designs.

Signaling Pathways Triggering Therapeutic Hydrogels in Promoting Chronic Wound Healing

In recent years, there has been a significant increase in the prevalence of chronic wounds, such as pressure ulcers, diabetic foot ulcers, and venous ulcers of the lower extremities. The main contributors to chronic wound formation are bacterial infection, prolonged inflammation, and peripheral vascular disease. However, effectively treating these chronic wounds remains a global challenge. Hydrogels have extensively explored as wound healing dressing because of their excellent biocompatibility and structural similarity to extracellular matrix (ECM). Nonetheless, much is still unknown how the hydrogels promote wound repair and regeneration. Signaling pathways play critical roles in wound healing process by controlling and coordinating cells and biomolecules. Hydrogels, along with their therapeutic ingredients that impact signaling pathways, have the potential to significantly enhance the wound healing process and its ultimate outcomes. Understanding this interaction will undoubtedly provide new insights into developing advanced hydrogels for wound repair and regeneration. This paper reviews the latest studies on classical signaling pathways and potential targets influenced by hydrogel scaffolds in chronic wound healing. This work hopes that it will offer a different perspective in developing more efficient hydrogels for treating chronic wounds.

Designing Composite Stimuli-Responsive Hydrogels for Wound Healing Applications: The State-of-the-Art and Recent Discoveries

Effective wound treatment has become one of the most important challenges for healthcare as it continues to be one of the leading causes of death worldwide. Therefore, wound care technologies significantly evolved in order to provide a holistic approach based on various designs of functional wound dressings. Among them, hydrogels have been widely used for wound treatment due to their biocompatibility and similarity to the extracellular matrix. The hydrogel formula offers the control of an optimal wound moisture level due to its ability to absorb excess fluid from the wound or release moisture as needed. Additionally, hydrogels can be successfully integrated with a plethora of biologically active components (e.g., nanoparticles, pharmaceuticals, natural extracts, peptides), thus enhancing the performance of resulting composite hydrogels in wound healing applications. In this review, the-state-of-the-art discoveries related to stimuli-responsive hydrogel-based dressings have been summarized, taking into account their antimicrobial, anti-inflammatory, antioxidant, and hemostatic properties, as well as other effects (e.g., re-epithelialization, vascularization, and restoration of the tissue) resulting from their use.

Temperature-sensitive multifunctional intelligent responsive hydrogel based on carboxymethyl agarose and N-isopropylacrylamide: Controlled drug release and accelerated wound healing

Wound healing remains challenging due to posttraumatic pain. At present, most wound dressings ignore the importance of wound pain. In this study, a temperature-sensitive multifunctional intelligent hydrogel patch (CPAG) containing lidocaine has developed for wound healing. CPAG hydrogel was prepared by grafting N-isopropylacrylamide and acrylamide onto carboxymethyl agarose (CMA) modified by agarose and encapsulating gallic acid and lidocaine. FTIR, 1H NMR spectroscopy, SEM and rheology were used to investigate its structure and temperature-sensitive properties. The contraction force generated by the temperature response characteristics of CPAG at 30 °C can accelerate wound healing. In vitro release assays demonstrated that CPAG directly controlled the same amount of lidocaine release at different temperatures through the competition between polymer-polymer and polymer-water interactions. In addition, MTT, H&E staining and stimulation test further proved its biological safety. The pain behavior study showed that the pain inhibition rates of the lidocaine cataplasms and LID@CPAG were 51.16 % and 67.83 %, respectively. In vitro and in vivo studies have shown that compared with the blank group, the bleeding volume of LID@CPAG decreased by 54.3 %, and the wound healing rate reached 97 %. CPAG hydrogel can play a comprehensive therapeutic role in accelerating wound closure by controlling drug release, analgesia, antioxidation and hemostasis.

Research progress related to thermosensitive hydrogel dressings in wound healing: a review

Wound healing is a dynamic and complex process in which the microenvironment at the wound site plays an important role. As a common material for wound healing, dressings accelerate wound healing and prevent external wound infections. Hydrogels have become a hot topic in wound-dressing research because of their high water content, good biocompatibility, and adjustable physical and chemical properties. Intelligent hydrogel dressings have attracted considerable attention because of their excellent environmental responsiveness. As smart polymer hydrogels, thermosensitive hydrogels can respond to small temperature changes in the environment, and their special properties make them superior to other hydrogels. This review mainly focuses on the research progress in thermosensitive intelligent hydrogel dressings for wound healing. Polymers suitable for hydrogel formation and the appropriate molecular design of the hydrogel network to achieve thermosensitive hydrogel properties are discussed, followed by the application of thermosensitive hydrogels as wound dressings. We also discuss the future perspectives of thermosensitive hydrogels as wound dressings and provide systematic theoretical support for wound healing.

Temperature-Sensitive Nanocarbon Hydrogel for Photothermal Therapy of Tumors

Background

Intelligent hydrogels continue to encounter formidable obstacles in the field of cancer treatment. A wide variety of hydrogel materials have been designed for diverse purposes, but materials with satisfactory therapeutic effects are still urgently needed.

Methods

Here, we prepared an injectable hydrogel by means of physical crosslinking. Carbon nanoparticle suspension injection (CNSI), a sentinel lymph node imaging agent that has been widely used in the clinic, with sodium β-glycerophosphate (β-GP) were added to a temperature-sensitive chitosan (CS) hydrogel (CS/GP@CN) as an agent for photothermal therapy (PTT). After evaluating the rheological, morphological, and structural properties of the hydrogel, we used 4T1 mouse breast cancer cells and B16 melanoma cells to assess its in vitro properties. Then, we intratumorally injected the hydrogel into BALB/c tumor-bearing mice to assess the in vivo PTT effect, antitumor immune response and the number of lung metastases.

Results

Surprisingly, this nanocarbon hydrogel called CS/GP@CN hydrogel not only had good biocompatibility and a great PTT effect under 808nm laser irradiation but also facilitated the maturation of dendritic cells to stimulate the antitumor immune response and had an extraordinary antimetastatic effect in the lungs.

Discussion

Overall, this innovative temperature-sensitive nanocarbon hydrogel, which exists in a liquid state at room temperature and transforms to a gel at 37 °C, is an outstanding local delivery platform with tremendous PTT potential and broad clinical application prospects.

An injectable, self-healable, antibacterial, and pro-healing oxidized pullulan polysaccharide/carboxymethyl chitosan hydrogel for early protection of open abdominal wounds

Open abdomen (OA) is an effective method for treating critical abdominal conditions such as severe abdominal infections. The temporary abdominal closure (TAC) technique is often used to temporarily restore the physiological environment of the abdominal cavity and maintain the homeostatic balance of the abdominal cavity. However, most of the common TAC materials available today lack bio-responsiveness, tend to abrade the intestinal canal, and lead to delayed tissue healing of the wound. Hydrogels could mimic the extracellular matrix and have shown significant potential in life science fields such as tissue regeneration, wound repair, and controlled drug release. In this study, a composite hydrogel scaffold was constructed by the Schiff base reaction of oxidized pullulan polysaccharide with carboxymethyl chitosan. The hydrogel exhibited excellent self-healing, cellular biocompatibility, and antibacterial and anti-inflammatory abilities, and in experiments it reduced secondary damage caused by friction between tissue and patch, thereby preventing serious complications such as intestinal fistula, promoted M1-M2 polarization of macrophages, reduced the inflammatory response, regulated the inflammatory microenvironment in vivo, promoted angiogenesis and granulation tissue regeneration, and accelerated wound healing. Therefore, our hydrogel provides a new strategy for material-assisted wound protection during OA and has potential clinical applications.

pH-responsive scaffolds for tissue regeneration: In vivo performance

A myriad of pH-sensitive scaffolds has been reported in recent decades. Information on their behaviour in vitro under conditions that mimic the pH changes that occur during tissue regeneration is abundant. Differently, the in vivo demonstration of the advantages of pH-responsive systems in comparison with non-responders is more limited. The in vivo scenario is very complex and the intricate relationship between the host response, the overall pathological conditions of the patient, and the risk of colonization by microorganisms is very difficult to imitate in in vitro tests. This review aims to shed light on how the changes in pH between healthy and damaged states and also during the healing process have been exploited so far to develop polymer-based scaffolds that actively contribute in vivo to the healing process avoiding chronification. The main strategies so far tested to prepare pH-responsive scaffolds rely on (i) changes in ionization of natural polymers, ionizable monomers and clays, (ii) reversible cross-linkers, (iii) coatings, and (iv) production of CO2 gas. These strategies are analysed in detail in this review with the description of relevant examples of their performance on specific animal models. The versatility of the techniques used to prepare biocompatible and environment-friendly pH-responsive scaffolds that have been implemented in the last decade may pave the way for a successful translation to the clinic. STATEMENT OF SIGNIFICANCE: We report here on the most recent advances in pH-responsive polymer-based scaffolds that have been demonstrated in vivo to be suitable for wound and bone healing. pH is a critical variable in the tissue regeneration process, and small changes can speed up or completely stop the process. Although there is still a paucity of information on the performance in the complex in vivo environment, recently reported achievements using scaffolds endowed with pH-responsiveness through ionic natural polymers, ionizable monomers and clays, reversible cross-linkers, coatings, or formation of CO2 ensure a promising future towards clinical translation.