Development of Hydrogel‐Based Sprayable Wound Dressings for Second‐ and Third‐Degree Burns

Sprayable biomimetic double mask with rapid autophasing and hierarchical programming for scarless wound healing

Current sprayable hydrogel masks lack the stepwise protection, cleansing, and nourishment of extensive wounds, leading to delayed healing with scarring. Here, we develop a sprayable biomimetic double wound mask (BDM) with rapid autophasing and hierarchical programming for scarless wound healing. The BDMs comprise hydrophobic poly (lactide-co-propylene glycol-co-lactide) dimethacrylate (PLD) as top layer and hydrophilic gelatin methacrylate (GelMA) hydrogel as bottom layer, enabling swift autophasing into bilayered structure. After photocrosslinking, BDMs rapidly solidify with strong interfacial bonding, robust tissue adhesion, and excellent joint adaptiveness. Upon implementation, the bottom GelMA layer could immediately release calcium ion for rapid hemostasis, while the top PLD layer could maintain a moist, breathable, and sterile environment. These traits synergistically suppress the inflammatory tumor necrosis factor-α pathway while coordinating the cyclic guanosine monophosphate/protein kinase G-Wnt/calcium ion signaling pathways to nourish angiogenesis. Collectively, our BDMs with self-regulated construction of bilayered structure could hierarchically program the healing progression with transformative potential for scarless wound healing.

Corticosteroid-loaded chitosan-based in-situ forming gel combined with microneedle technology for improvement of burn eschar wound healing

Burn is one of the most common skin injuries and accounts for 300,000 deaths annually. Debridement and antibiotic therapy are major burn treatments, however, as debridement is not always possible and many drugs have poor penetration into necrotic tissue, permeation enhancement is acquired. Another challenge is the short duration of topically applied drugs. This study aims to address both problems by combining in-situ forming gels and microneedles. A chitosan-based in-situ forming gel of hydrocortisone was applied to human burn eschar using microneedles. The formulation was optimized using Design-Expert software. Formulation characterization was done in terms of gelling time and temperature, thermal analysis, release phenomenon, rheology, texture analysis, and stability. Finally, animal studies on mice burn wound treatment were conducted. Results showed that optimized formulation controlled the drug release, and wherever microneedle was used, drug permeation and flux increased (P-value < 0.05). In all ex-vivo and in-vivo stages, gel plus microneedle (length of 1.5 mm and application mode of 2) produced the best results concerning increased flux and faster recovery of burn eschar. In conclusion, the in-situ forming gel with appropriate texture, quality, and stability in combination with microneedle can be a good candidate for the controlled release of drugs in third-degree burn eschars.

Exploring the underlying pharmacological, immunomodulatory, and anti-inflammatory mechanisms of phytochemicals against wounds: a molecular insight

BACKGROUND

Numerous cellular, humoral, and molecular processes are involved in the intricate process of wound healing.

PHARMACOLOGICAL RELEVANCE

Numerous bioactive substances, such as ß-sitosterol, tannic acid, gallic acid, protocatechuic acid, quercetin, ellagic acid, and pyrogallol, along with their pharmacokinetics and bioavailability, have been reviewed. These phytochemicals work together to promote angiogenesis, granulation, collagen synthesis, oxidative balance, extracellular matrix (ECM) formation, cell migration, proliferation, differentiation, and re-epithelialization during wound healing.

FINDINGS AND NOVELTY

To improve wound contraction, this review delves into how the application of each bioactive molecule mediates with the inflammatory, proliferative, and remodeling phases of wound healing to speed up the process. This review also reveals the underlying mechanisms of the phytochemicals against different stages of wound healing along with the differentiation of the in vitro evidence from the in vivo evidence There is growing interest in phytochemicals, or plant-derived compounds, due their potential health benefits. This calls for more scientific analysis and mechanistic research. The various pathways that these phytochemicals control/modulate to improve skin regeneration and wound healing are also briefly reviewed. The current review also elaborates the immunomodulatory modes of action of different phytochemicals during wound repair.

Stem Cells in Bone Tissue Engineering: Progress, Promises and Challenges

Bone defects from accidents, congenital conditions, and age-related diseases significantly impact quality of life. Recent advancements in bone tissue engineering (TE) involve biomaterial scaffolds, patient-derived cells, and bioactive agents, enabling functional bone regeneration. Stem cells, obtained from numerous sources including umbilical cord blood, adipose tissue, bone marrow, and dental pulp, hold immense potential in bone TE. Induced pluripotent stem cells and genetically modified stem cells can also be used. Proper manipulation of physical, chemical, and biological stimulation is crucial for their proliferation, maintenance, and differentiation. Stem cells contribute to osteogenesis, osteoinduction, angiogenesis, and mineralization, essential for bone regeneration. This review provides an overview of the latest developments in stem cell-based TE for repairing and regenerating defective bones.

Development of a Sprayable Hydrogel-Based Wound Dressing: An In Vitro Model

Hydrogel-based dressings can effectively heal wounds by providing multiple functions, such as antibacterial, anti-inflammatory, and preangiogenic bioactivities. The ability to spray the dressing is important for the rapid and effective coverage of the wound surface. In this study, we developed a sprayable hydrogel-based wound dressing using naturally derived materials: hyaluronic acid and gelatin. We introduced methacrylate groups (HAMA and GelMA) to these materials to enable controllable photocrosslinking and form a stable hydrogel on the wound surface. To achieve sprayability, we evaluated the concentration of GelMA within a range of 5-15% (w/v) and then incorporated 1% (w/v) HAMA. Additionally, we incorporated calcium peroxide into the hydrogel at concentrations ranging from 0 to 12 mg/mL to provide self-oxygenation and antibacterial properties. The results showed that the composite hydrogels were sprayable and could provide oxygen for up to two weeks. The released oxygen relieved metabolic stress in fibroblasts and reduced cell death under hypoxia in in vitro culture. Furthermore, calcium peroxide added antibacterial properties to the wound dressing. In conclusion, the developed sprayable hydrogel dressing has the potential to be advantageous for wound healing due to its practical and conformable application, as well as its self-oxygenating and antibacterial functions.

Stimuli-responsive polysaccharide-based smart hydrogels for diabetic wound healing: Design aspects, preparation methods and regulatory perspectives

Diabetes adversely affects wound-healing responses, leading to the development of chronic infected wounds. Such wound microenvironment is characterized by hyperglycaemia, hyperinflammation, hypoxia, variable pH, upregulation of matrix metalloproteinases, oxidative stress, and bacterial colonization. These pathological conditions pose challenges for the effective wound healing. Therefore, there is a paradigm shift in diabetic wound care management wherein abnormal pathological conditions of the wound microenvironment is used as a trigger for controlling the drug release or to improve properties of wound dressings. Hydrogels composed of natural polysaccharides showed tremendous potential as wound dressings as well as stimuli-responsive materials due to their unique properties such as biocompatibility, biodegradability, hydrophilicity, porosity, stimuli-responsiveness etc. Hence, polysaccharide-based hydrogels have emerged as advanced healthcare materials for diabetic wounds. In this review, we presented important aspects for the design of hydrogel-based wound dressings with an emphasis on biocompatibility, biodegradability, entrapment of therapeutic agents, moisturizing ability, swelling, and mechanical properties. Further, various crosslinking methods that enable desirable properties and stimuli responsiveness to the hydrogels have been mentioned. Subsequently, state-of-the-art developments in mono- and multi- stimuli-responsive hydrogels have been presented along with the case studies. Finally regulatory perspectives, challenges for the clinical translation and future prospects have been discussed.

Aloe vera-Based Hydrogels for Wound Healing: Properties and Therapeutic Effects

Aloe vera-based hydrogels have emerged as promising platforms for the delivery of therapeutic agents in wound dressings due to their biocompatibility and unique wound-healing properties. The present study provides a comprehensive overview of recent advances in the application of Aloe vera-based hydrogels for wound healing. The synthesis methods, structural characteristics, and properties of Aloe vera-based hydrogels are discussed. Mechanisms of therapeutic agents released from Aloe vera-based hydrogels, including diffusion, swelling, and degradation, are also analyzed. In addition, the therapeutic effects of Aloe vera-based hydrogels on wound healing, as well as the reduction of inflammation, antimicrobial activity, and tissue regeneration, are highlighted. The incorporation of various therapeutic agents, such as antimicrobial and anti-inflammatory ones, into Aloe vera-based hydrogels is reviewed in detail. Furthermore, challenges and future prospects of Aloe vera-based hydrogels for wound dressing applications are considered. This review provides valuable information on the current status of Aloe vera-based hydrogels for the delivery of therapeutic agents in wound dressings and highlights their potential to improve wound healing outcomes.

Zwitterionic Polysaccharide-Based Hydrogel Dressing as a Stem Cell Carrier to Accelerate Burn Wound Healing

Stem cell therapy integrated with hydrogels has shown promising potential in wound healing. However, the existing hydrogels usually cannot reach the desired therapeutic efficacy for burn wounds due to the inadaptability to wound shape and weak anti-infection ability. Moreover, it is difficult to improve the environment for the survival and function of stem cells under complicated wound microenvironments. In this study, an injectable and self-healing hydrogel (DSC), comprising sulfobetaine-derived dextran and carboxymethyl chitosan, is fabricated through a Schiff-base reaction. Meanwhile, the DSC hydrogel shows high nonfouling properties, including resistance to bacteria and nonspecific proteins; moreover, the prepared hydrogel can provide a biomimetic microenvironment for cell proliferation whilst maintaining the stemness of adipose-derived stem cells (ADSCs) regardless of complex microenvironments. In burnt murine animal models, the ADSCs-laden hydrogel can significantly accelerate wound healing rate and scarless skin tissue regeneration through multiple pathways. Specifically, the ADSCs-laden DSC hydrogel can avoid immune system recognition and activation and thus reduce the inflammatory response. Moreover, the ADSCs-laden DSC hydrogel can promote collagen deposition, angiogenesis, and enhance macrophage M2 polarization in the wound area. In summary, sulfobetaine-derived polysaccharide hydrogel can serve as a versatile platform for stem cell delivery to promote burn wound healing.

Harnessing the potential of oxygen-generating materials and their utilization in organ-specific delivery of oxygen

The limited availability of transplantable organs hinders the success of patient treatment through organ transplantation. In addition, there are challenges with immune rejection and the risk of disease transmission when receiving organs from other individuals. Tissue engineering aims to overcome these challenges by generating functional three-dimensional (3D) tissue constructs. When developing tissues or organs of a particular shape, structure, and size as determined by the specific needs of the therapeutic intervention, a tissue specific oxygen supply to all parts of the tissue construct is an utmost requirement. Moreover, the lack of a functional vasculature in engineered tissues decreases cell survival upon implantation in the body. Oxygen-generating materials can alleviate this challenge in engineered tissue constructs by providing oxygen in a sustained and controlled manner. Oxygen-generating materials can be incorporated into 3D scaffolds allowing the cells to receive and utilize oxygen efficiently. In this review, we present an overview of the use of oxygen-generating materials in various tissue engineering applications in an organ specific manner as well as their potential use in the clinic.

Combinational System of Lipid-Based Nanocarriers and Biodegradable Polymers for Wound Healing: An Updated Review

Skin wounds have imposed serious socioeconomic burdens on healthcare providers and patients. There are just more than 25,000 burn injury-related deaths reported each year. Conventional treatments do not often allow the re-establishment of the function of affected regions and structures, resulting in dehydration and wound infections. Many nanocarriers, such as lipid-based systems or biobased and biodegradable polymers and their associated platforms, are favorable in wound healing due to their ability to promote cell adhesion and migration, thus improving wound healing and reducing scarring. Hence, many researchers have focused on developing new wound dressings based on such compounds with desirable effects. However, when applied in wound healing, some problems occur, such as the high cost of public health, novel treatments emphasizing reduced healthcare costs, and increasing quality of treatment outcomes. The integrated hybrid systems of lipid-based nanocarriers (LNCs) and polymer-based systems can be promising as the solution for the above problems in the wound healing process. Furthermore, novel drug delivery systems showed more effective release of therapeutic agents, suitable mimicking of the physiological environment, and improvement in the function of the single system. This review highlights recent advances in lipid-based systems and the role of lipid-based carriers and biodegradable polymers in wound healing.

Oxygen-Generating Scaffolds: One Step Closer to the Clinical Translation of Tissue Engineered Products

The lack of oxygen supply in engineered constructs has been an ongoing challenge for tissue engineering and regenerative medicine. Upon implantation of an engineered tissue, spontaneous blood vessel formation does not happen rapidly, therefore, there is typically a limited availability of oxygen in engineered biomaterials. Providing oxygen in large tissue-engineered constructs is a major challenge that hinders the development of clinically relevant engineered tissues. Similarly, maintaining adequate oxygen levels in cell-laden tissue engineered products during transportation and storage is another hurdle. There is an unmet demand for functional scaffolds that could actively produce and deliver oxygen, attainable by incorporating oxygen-generating materials. Recent approaches include encapsulation of oxygen-generating agents such as solid peroxides, liquid peroxides, and fluorinated substances in the scaffolds. Recent approaches to mitigate the adverse effects, as well as achieving a sustained and controlled release of oxygen, are discussed. Importance of oxygen-generating materials in various tissue engineering approaches such as ex vivo tissue engineering, in situ tissue engineering, and bioprinting are highlighted in detail. In addition, the existing challenges, possible solutions, and future strategies that aim to design clinically relevant multifunctional oxygen-generating biomaterials are provided in this review paper.

Can We Structure Biomaterials to Spray Well Whilst Maintaining Functionality?

Structured fluid biomaterials, including gels, creams, emulsions and particle suspensions, are used extensively across many industries, including great interest within the medical field as controlled release vehicles to improve the therapeutic benefit of delivered drugs and cells. Colloidal forces within these materials create multiscale cohesive interactions, giving rise to intricate microstructures and physical properties, exemplified by increasingly complex mathematical descriptions. Yield stresses and viscoelasticity, typically arising through the material microstructure, vastly improve site-specific retention, and protect valuable therapeutics during application. One powerful application route is spraying, a convenient delivery method capable of applying a thin layer of material over geometrically uneven surfaces and hard-to-reach anatomical locations. The process of spraying is inherently disruptive, breaking a bulk fluid in successive steps into smaller elements, applying multiple forces over several length scales. Historically, spray research has focused on simple, inviscid solutions and dispersions, far from the complex microstructures and highly viscoelastic properties of concentrated colloidal biomaterials. The cohesive forces in colloidal biomaterials appear to conflict with the disruptive forces that occur during spraying. This review explores the physical bass and mathematical models of both the multifarious material properties engineered into structured fluid biomaterials and the disruptive forces imparted during the spray process, in order to elucidate the challenges and identify opportunities for rational design of sprayable, structured fluid biomaterials.

Walnut ointment promotes full-thickness burning wound healing: role of linoleic acid

PURPOSE

To investigate the active ingredients of walnut ointment (WO) and its mechanism in repairing wounds.

METHODS

The ingredients of WO were detected by gas chromatography-mass spectrometry. The effect of linoleic acid (LA) was tested by in vitro Alamar Blue (AB) reagent. Image J software, histological and immunohistochemical analysis were used to confirm the healing effect of LA in the porcine skin model. The animals were euthanized after the experiment by injection of pentobarbital sodium.

RESULTS

LA, 24% in WO, promotes keratinocytes and fibroblasts proliferation, which were 50.09% and 15.07% respectively higher than control (p < 0.05). The healing rate of the LA group (96.02% ± 2%, 98.58% ± 0.78%) was higher than the saline group (82.11% ± 3.37%, 88.72% ± 1.73%) at week 3 and week 4 (p < 0.05). The epidermal thickness of the LA was 0.16 ± 0.04 mm greater and the expression of the P63 and CK10 proteins was stronger in the LA group than the control (p < 0.05).

CONCLUSIONS

LA, which is the main components in WO can promote full-thickness burning wounds (FBWs) by stimulating cell proliferation and differentiation.

Functional Hydrogels for Treatment of Chronic Wounds

Chronic wounds severely affect 1-2% of the population in developed countries. It has been reported that nearly 6.5 million people in the United States suffer from at least one chronic wound in their lifetime. The treatment of chronic wounds is critical for maintaining the physical and mental well-being of patients and improving their quality of life. There are a host of methods for the treatment of chronic wounds, including debridement, hyperbaric oxygen therapy, ultrasound, and electromagnetic therapies, negative pressure wound therapy, skin grafts, and hydrogel dressings. Among these, hydrogel dressings represent a promising and viable choice because their tunable functional properties, such as biodegradability, adhesivity, and antimicrobial, anti-inflammatory, and pre-angiogenic bioactivities, can accelerate the healing of chronic wounds. This review summarizes the types of chronic wounds, phases of the healing process, and key therapeutic approaches. Hydrogel-based dressings are reviewed for their multifunctional properties and their advantages for the treatment of chronic wounds. Examples of commercially available hydrogel dressings are also provided to demonstrate their effectiveness over other types of wound dressings for chronic wound healing.