Scar-Free Healing: Current Concepts and Future Perspectives

Accelerated, injectable, self-healing, scarless wound dressings using rGO reinforced dextran/chitosan hydrogels incorporated with PDA-loaded asiaticoside

The process of wound healing is intricate and complex, necessitating the intricate coordination of various cell types and bioactive molecules. Despite significant advances, challenges persist in achieving accelerated healing and minimizing scar formation. Herein, a multifunctional hydrogel engineered via dynamic Schiff base crosslinking between oxidized dextran and quaternized chitosan, reinforced with reduced graphene oxide (rGO) is reported. The resulting OQG hydrogels demonstrated injectability to aid in conforming to irregular wound geometries, rapid self-healing to maintain structural integrity and adhesion for intimate integration with wound beds. Moreover, the developed hydrogels possessed antioxidant and antibacterial activities, mitigating inflammation and preventing infection. The incorporation of conductive rGO further facilitated the transmission of endogenous electrical signals, stimulating cell migration and tissue regeneration. In addition, the polydopamine-encapsulated asiaticoside (AC@PDA) nanoparticles were encapsulated in OQG hydrogels to reduce scar formation during in vivo evaluations. In vitro results confirmed the histocompatibility of the hydrogels to promote cell migration. The recovery of the full-thickness rat wounds revealed that these designed OQG hydrogels with the incorporation of AC@PDA nanoparticles could accelerate wound healing, reduce inflammation, facilitate angiogenesis, and minimize scarring when implemented. This multifunctional hydrogel system offers a promising strategy for enhanced wound management and scarless tissue regeneration, addressing the multifaceted challenges in wound care.

An Integrated Computational and Experimental Approach to Formulate Tamanu Oil Bigels as Anti-Scarring Agent

Tamanu oil has traditionally been used to treat various skin problems. The oil has wound-healing and skin-regenerating capabilities and encourages the growth of new skin cells, all of which are helpful for fading scars and hyperpigmentation, as well as promoting an all-around glow. The strong nutty odor and high viscosity are the major disadvantages associated with its application. The aim of this study was to create bigels using tamanu oil for its anti-scarring properties and predict the possible mechanism of action through the help of molecular docking studies. In silico studies were performed to analyze the binding affinity of the protein with the drug, and the anti-scarring activity was established using a full-thickness excision wound model. In silico studies revealed that the components inophyllum C, 4-norlanosta-17(20),24-diene-11,16-diol-21-oic acid, 3-oxo-16,21-lactone, calanolide A, and calophyllolide had docking scores of -11.3 kcal/mol, -11.1 kcal/mol, -9.8 kcal/mol, and -8.6 kcal/mol, respectively, with the cytokine TGF-β1 receptor. Bigels were prepared with tamanu oil ranging from 5 to 20% along with micronized xanthan gum and evaluated for their pH, viscosity, and spreadability. An acute dermal irritation study in rabbits showed no irritation, erythema, eschar, or edema. In vivo excisional wound-healing studies performed on Wistar rats and subsequent histopathological studies showed that bigels had better healing properties when compared to the commercial formulation (MurivennaTM oil). This study substantiates the wound-healing and scar reduction potential of tamanu oil bigels.

Synergistic effect of chitosan-alginate composite hydrogel enriched with ascorbic acid and alpha-tocopherol under hypoxic conditions on the behavior of mesenchymal stem cells for wound healing

BACKGROUND

In regenerative medicine, especially skin tissue engineering, the focus is on enhancing the quality of wound healing. Also, several constructs with different regeneration potentials have been used for skin tissue engineering. In this study, the regenerative properties of chitosan-alginate composite hydrogels in skin wound healing under normoxic and hypoxic conditions were investigated in vitro.

METHODS

The ionic gelation method was used to prepare chitosan/alginate (CA) hydrogel containing CA microparticles and bioactive agents [ascorbic acid (AA) and α-tocopherol (TP)]. After preparing composite hydrogels loaded with AA and TP, the physicochemical properties such as porosity, pore size, swelling, weight loss, wettability, drug release, and functional groups were analyzed. Also, the hemo-biocompatibility of composite hydrogels was evaluated by a hemolysis test. Then, the rat bone marrow mesenchymal stem cells (rMSCs) were seeded onto the hydrogels after characterization by flow cytometry. The survival rate was analyzed using MTT assay test. The hydrogels were also investigated by DAPI and H&E staining to monitor cell proliferation and viability. To induce hypoxia, the cells were exposed to CoCl2. To evaluate the regenerative potential of rMSCs cultured on CA/AA/TP hydrogels under hypoxic conditions, the expression of the main genes involved in the healing of skin wounds, including HIF-1α, VEGF-A, and TGF-β1, was investigated by real-time PCR.

RESULTS

The results demonstrated that the prepared composite hydrogels were highly porous, with interconnected pores that ranged in sizes from 20 to 188 μm. The evaluation of weight loss showed that the prepared hydrogels have the ability to biodegrade according to the goals of wound healing. The reduction percentage of CA/AA/TP mass in 21 days was reported as 21.09 ± 0.52%. Also, based on wettability and hemolysis tests of the CA/AA/TP, hydrophilicity (θ = 55.6° and 53.7°) and hemocompatibility with a hemolysis ratio of 1.36 ± 0.19 were evident for them. Besides, MTT assay, DAPI, and H&E staining also showed that the prepared hydrogels provide a suitable substrate for cell growth and proliferation. Finally, based on real-time PCR, increased expression levels of VEGF and TGF-β1 were observed in rMSCs in hypoxic conditions cultured on the prepared hydrogels.

CONCLUSIONS

In conclusion, this study provides evidence that 3D CA/AA/TP composite hydrogels seeded by rMSCs in hypoxic conditions have great potential to improve wound healing.

Effects of Factors Influencing Scar Formation on the Scar Microbiome in Patients with Burns

Skin microbiome dysbiosis has deleterious effects, and the factors influencing burn scar formation, which affects the scar microbiome composition, are unknown. Therefore, we investigated the effects of various factors influencing scar formation on the scar microbiome composition in patients with burns. We collected samples from the burn scar center and margin of 40 patients with burns, subgrouped by factors influencing scar formation. Scar microbiome composition-influencing factors were analyzed using univariate and multivariate analyses. Skin graft, hospitalization period, intensive care unit (ICU) admission, burn degree, sex, age, total body surface area burned (TBSA), time post-injury, transepidermal water loss, the erythrocyte sedimentation rate, and C-reactive protein levels were identified as factors influencing burn scar microbiome composition. Only TBSA and ICU admission were associated with significant differences in alpha diversity. Alpha diversity significantly decreased with an increase in TBSA and was significantly lower in patients admitted to the ICU than in those not admitted to the ICU. Furthermore, we identified microorganisms associated with various explanatory variables. Our cross-sectional systems biology study confirmed that various variables influence the scar microbiome composition in patients with burns, each of which is associated with various microorganisms. Therefore, these factors should be considered during the application of skin microbiota for burn scar management.

Effects of ultrashort wave diathermy on skin wounds in rabbit ears

PURPOSE

Ultrashort wave diathermy (USWD) is commonly used in diseases associated with osteoarticular and soft tissue injuries. However, while accelerating wound healing and preventing joint stiffness, there have been few reports on whether it leads to excessive hypertrophic scarring. The aim was to investigate the effects of different doses of USWD on hypertrophic scars.

MATERIALS AND METHODS

A rabbit model of hypertrophic scars was used to determine which dose of USWD reduced scar hyperplasia. The scar thickness was calculated using Sirius red staining. All protein expression levels were determined by western blotting, including fibrosis, collagen deposition, and neoangiogenesis related proteins. Subsequently, flow cytometry and ELISAs were used to determine the proportions of macrophage and inflammatory levels.

RESULTS

The wounds with USWD in histopathology showed the dermis was more markedly thickened in the 120 mA group, whereas the wounds with the 60 mA were less raised, comparing with the 0 mA; all detected protein levels were increased significantly, the 120 mA group comparing with the others, including heat shock, fibrosis, and neoangiogenesis, whereas the collagen deposition relative protein levels were decreased, the 60 mA group comparing with Sham group; Finally, in the proportion of macrophages and inflammatory levels the 120 mA group were the highest, and the group Sham was lower than group 60 mA.

CONCLUSIONS

In hypertrophic scars, the 60 mA USWD could relieve scar formation and inflammatory reactions; however, higher doses could result in opposite consequences.

Animal tissue-derived biomaterials for promoting wound healing

The skin serves as the primary barrier between the human body and external environment, and is therefore susceptible to damage from various factors. In response to this challenge, animal tissue-derived biomaterials have emerged as promising candidates for wound healing due to their abundant sources, low side-effect profiles, exceptional bioactivity, biocompatibility, and unique extracellular matrix (ECM) mimicry. The evolution of modern engineering technology and therapies has allowed these animal tissue-derived biomaterials to be transformed into various forms and modified to possess the necessary properties for wound repair. This review provides an overview of the wound healing process and the factors that influence it. We then describe the extraction methods, important properties, and recent practical applications of various animal tissue-derived biomaterials. Our focus then shifts to the critical properties of these biomaterials in skin wound healing and their latest research developments. Finally, we critically examine the limitations and future prospects of biomaterials generated from animal tissues in this field.

Fabrication and desired properties of conductive hydrogel dressings for wound healing

Conductive hydrogels are platforms recognized as constituting promising materials for tissue engineering applications. This is because such conductive hydrogels are characterized by the inherent conductivity properties while retaining favorable biocompatibility and mechanical properties. These conductive hydrogels can be particularly useful in enhancing wound healing since their favorable conductivity can promote the transport of essential ions for wound healing via the imposition of a so-called transepithelial potential. Other valuable properties of these conductive hydrogels, such as wound monitoring, stimuli-response etc., are also discussed in this study. Crucially, the properties of conductive hydrogels, such as 3D printability and monitoring properties, suggest the possibility of its use as an alternative wound dressing to traditional dressings such as bandages. This review, therefore, seeks to comprehensively explore the functionality of conductive hydrogels in wound healing, types of conductive hydrogels and their preparation strategies and crucial properties of hydrogels. This review will also assess the limitations of conductive hydrogels and future perspectives, with an emphasis on the development trend for conductive hydrogel uses in wound dressing fabrication for subsequent clinical applications.

Repairing Small Facial Soft Tissue Defects by Tissue Regeneration in Asians

BACKGROUND

A variety of options are available to repair the small facial soft tissue defects after surgical removal of cutaneous tumor, including direct suture, skin grafts, local, regional or free flaps. However, tissue regeneration is another option for repairing facial defects. This study proposes the clinical application of the principle of tissue regeneration priority in small defects (diameter <1.3 cm) of facial soft tissue.

METHODS

A retrospective study of 33 patients whose facial defects were repaired by tissue regeneration healing in situ from January 2019 to January 2022. In this group, the facial soft tissue defects were treated with wound moist theory in order to promote wound regeneration.

RESULT

All patients underwent 1 month follow-up at least and the longest follow-up time was 6 months. Hundred percent of the patients were satisfied with their cosmetic outcome. Only some patients formed small depression scars after surgery, the appearance of which were similar to acne scar. In this situation, re-resection and laser treatment could be used as complementary procedures. However, no patient underwent the secondary treatments including laser and re-resection.

CONCLUSION

Healing by tissue regeneration is an effective option for the facial defects in Asians. For most of the small soft tissue defects of the face, tissue regeneration in situ can achieve satisfactory effects. More importantly, it has the advantages of simple operation and fewer complications.

Burn Wound Bed Management

Critical to the success of modern burn care is the management of the burn wound. Timely and complete removal of nonviable tissue is complicated by the irreplaceable nature of the tissue lost either through the burn injury or as "collateral damage" as part of the treatment. Challenges in distinguishing between viable and nonviable tissue and "replacing the irreplaceable" are discussed alongside potential disruptive technologies which could fundamentally change how burn care is delivered. Advances in burn wound bed management forms the foundation on which the goal of zero preventable death and disability after burn injury can be achieved.

New insights into balancing wound healing and scarless skin repair

Scars caused by skin injuries after burns, wounds, abrasions and operations have serious physical and psychological effects on patients. In recent years, the research of scar free wound repair has been greatly expanded. However, understanding the complex mechanisms of wound healing, in which various cells, cytokines and mechanical force interact, is critical to developing a treatment that can achieve scarless wound healing. Therefore, this paper reviews the types of wounds, the mechanism of scar formation in the healing process, and the current research progress on the dual consideration of wound healing and scar prevention, and some strategies for the treatment of scar free wound repair.

Down-Regulating Scar Formation by Microneedles Directly via a Mechanical Communication Pathway

Excessive extracellular matrix deposition drives fibroblasts into a state of high mechanical stress, exacerbating pathological fibrosis and hypertrophic scar formation, leading to tissue dysfunction. This study reports a minimally invasive and convenient approach to obtaining scarless tissue using a silk fibroin microneedle patch (SF MNs). We found that by tuning the MN size and density only, the biocompatible MNs significantly decreased the scar elevation index in the rabbit ear hypertrophic scar model and increased ultimate tensile strength close to regular skin. To advance our understanding of this recent approach, we built a fibroblast-populated collagen lattice system and finite element model to study MN-mediated cellular behavior of fibroblasts. We found that the MNs reduced the fibroblasts generated contraction and mechanical stress, as indicated by decreased expression of the mechanical sensitive gene ANKRD1. Specifically, SF MNs attenuated the integrin-FAK signaling and consequently down-regulated the expression of TGF-β1, α-SMA, collagen I, and fibronectin. It resulted in a low-stress microenvironment that helps to reduce scar formation significantly. Microneedles' physical intervention via the mechanotherapeutic strategy is promising for scar-free wound healing.

Regenerative repair of full thickness skin wound assisted by dual crosslinking percolative gel casting maneuvered alginate hydrogel embedded with honey ghee blend resembles standard cutaneous properties

We report synergism in scarless cutaneous wound repair by alginate hydrogel (HGSAG) embedded with an optimized blend of characterized Jamun honey and characterized indigenously prepared ghee. Thorough screening and characterization of honey and ghee are carried out followed by obtaining a novel dual crosslinking percolative gel casting fabrication method to come up with HGSAG showing superior chemical stability, and mechanical strength (Nanoindentation study; lowest stiffness: 0.71 ± 0.19 μN/nm), and surface morphology (SEM; highest roughness: 0.13 ± 0.04 μm) to other variants. In vitro swelling study and degradation behavior study show intermediate swelling (swelling index: 0.59 ± 0.008 in 98 h) and required restricted degradation (PBS: 73.38 ± 0.55%, DMEM: 83.48 ± 0.69% in 10 days) for HGSAG which is necessary for providing nutrients to cells and in vivo therapeutic efficacy. We observe the remarkable antibacterial efficacy of HGSAG against Staphylococcus mutans and Escherichia coli. This particular substrate also shows decent 3T3 fibroblasts viability, cell-cell communication followed by cell-matrix interaction, and proliferation compared to other variants. Molecular gene expression studies by quantitative RT-PCR technique reveal strong upregulation of collagen I, CD26, and TGF-β3 while downregulation in the case of TGF-β1 which eventually substantiates scarless wound healing potential of HGSAG. Wound closure kinetics is most rapidly and successfully underpinned by HGSAG while compared to other alternatives including marketed healing patches. Regular close monitoring using histopathological studies and real-time imaging by Swept-Source Optical Coherence Tomography of in vivo wound model treated with HGSAG come up with the fascinating result of scarless healing (HGSAG treated epithelial thickness: 62.96 ± 0.67 μm, unwounded akin epithelial thickness: 62.56 ± 0.34 μm) within 12 days of wounding. Thus, the work highlights modified and stabilized alginate hydrogel embedded with honey and ghee blend as a potential scarless full-thickness cutaneous wound healing bio-scaffold.

A hybrid hydrogel composed of chitin and β-glucan for effectively management of wound healing and scarring

Non-functional scar commonly forms after the skin injury. At present, most of the clinical treatments for scar eradication are typically with long treatment courses, low curative effects and expensive. In...

The Role of Extracellular Matrix in Skin Wound Healing

Impaired wound healing is one of the unsolved problems of modern medicine, affecting patients’ quality of life and causing serious economic losses. Impaired wound healing can manifest itself in the form of chronic skin wounds or hypertrophic scars. Research on the biology and physiology of skin wound healing disorders is actively continuing, but, unfortunately, a single understanding has not been developed. The attention of clinicians to the biological and physiological aspects of wound healing in the skin is necessary for the search for new and effective methods of prevention and treatment of its consequences. In addition, it is important to update knowledge about genetic and non-genetic factors predisposing to impaired wound healing in order to identify risk levels and develop personalized strategies for managing such patients. Wound healing is a very complex process involving several overlapping stages and involving many factors. This thematic review focuses on the extracellular matrix of the skin, in particular its role in wound healing. The authors analyzed the results of fundamental research in recent years, finding promising potential for their transition into real clinical practice.

Construction of tissue-customized hydrogels from cross-linkable materials for effective tissue regeneration

Hydrogels are prevalent scaffolds for tissue regeneration because of their hierarchical architectures along with outstanding biocompatibility and unique rheological and mechanical properties. For decades, researchers have found that many materials (natural, synthetic, or hybrid) can form hydrogels using different cross-linking strategies. Traditional strategies for fabricating hydrogels include physical, chemical, and enzymatical cross-linking methods. However, due to the diverse characteristics of different tissues/organs to be regenerated, tissue-customized hydrogels need to be developed through precisely controlled processes, making the manufacture of hydrogels reliant on novel cross-linking strategies. Thus, hybrid cross-linkable materials are proposed to tackle this challenge through hybrid cross-linking strategies. Here, different cross-linkable materials and their associated cross-linking strategies are summarized. From the perspective of the major characteristics of the target tissues/organs, we critically analyze how different cross-linking strategies are tailored to fit the regeneration of such tissues and organs. To further advance this field, more appropriate cross-linkable materials and cross-linking strategies should be investigated. In addition, some innovative technologies, such as 3D bioprinting, the internet of medical things (IoMT), and artificial intelligence (AI), are also proposed to improve the development of hydrogels for more efficient tissue regeneration.

Marine Polysaccharides for Wound Dressings Application: An Overview

Wound dressings have become a crucial treatment for wound healing due to their convenience, low cost, and prolonged wound management. As cutting-edge biomaterials, marine polysaccharides are divided from most marine organisms. It possesses various bioactivities, which allowing them to be processed into various forms of wound dressings. Therefore, a comprehensive understanding of the application of marine polysaccharides in wound dressings is particularly important for the studies of wound therapy. In this review, we first introduce the wound healing process and describe the characteristics of modern commonly used dressings. Then, the properties of various marine polysaccharides and their application in wound dressing development are outlined. Finally, strategies for developing and enhancing marine polysaccharide wound dressings are described, and an outlook of these dressings is given. The diverse bioactivities of marine polysaccharides including antibacterial, anti-inflammatory, haemostatic properties, etc., providing excellent wound management and accelerate wound healing. Meanwhile, these biomaterials have higher biocompatibility and biodegradability compared to synthetic ones. On the other hand, marine polysaccharides can be combined with copolymers and active substances to prepare various forms of dressings. Among them, emerging types of dressings such as nanofibers, smart hydrogels and injectable hydrogels are at the research frontier of their development. Therefore, marine polysaccharides are essential materials in wound dressings fabrication and have a promising future.

Isotropic and Anisotropic Scaffolds for Tissue Engineering: Collagen, Conventional, and Textile Fabrication Technologies and Properties

In this review article, tissue engineering and regenerative medicine are briefly explained and the importance of scaffolds is highlighted. Furthermore, the requirements of scaffolds and how they can be fulfilled by using specific biomaterials and fabrication methods are presented. Detailed insight is given into the two biopolymers chitosan and collagen. The fabrication methods are divided into two categories: isotropic and anisotropic scaffold fabrication methods. Processable biomaterials and achievable pore sizes are assigned to each method. In addition, fiber spinning methods and textile fabrication methods used to produce anisotropic scaffolds are described in detail and the advantages of anisotropic scaffolds for tissue engineering and regenerative medicine are highlighted.

Substances for regenerative wound healing during antler renewal stimulated scar-less restoration of rat cutaneous wounds

Scarification is the outcome of cutaneous wound healing under normal conditions. Although considerable effort has been expended in this field, scar-less healing has not been achieved satisfactorily. The lack of a good model of scar-free healing has contributed to this undesirable situation. However, the annual regeneration of deer antlers, which starts from regenerative wound healing over the top of the pedicles (permanent bony protuberances), may provide such a model. Therefore, in this study, we investigated the process of pedicle wound healing at the organ, tissue, cell, and molecular levels. Our results convincingly demonstrate that wounds over the pedicle preceded a regenerative healing process including regeneration of skin appendages, such as hair follicles. Compared to the scar healing in rats, regenerative healing of the pedicle wound exhibited a weaker inflammatory response, lack of myofibroblast induction, and higher ratios of Col III/Col I, TGF-β3/TGF-β1, and MMP/TIMP. Importantly, our periosteal transplantation experiments in vivo revealed that this regenerative healing process was achieved through induction of antler stem cells (ASCs). Further study showed that this effect of ASCs on regenerative healing was not species-specific but more generic and could be applied to other mammalian species, as injection of ASCs stimulated regenerative healing of full-thickness excisional cutaneous wounds in rats. Overall, our findings show that ASCs may have therapeutic potential in enhancing the quality of wound healing and preventing scar formation in clinical settings.

An Autologous Protein-Based Topical Ointment for Hard-to-Heal Skin Wounds: A Multiple Case Series

BACKGROUND

There is increasing evidence regarding the wound healing potential of platelet-derived autologous by-products. We provide preliminary data regarding the use of a new plasma rich in growth factors-derived autologous topical ointment for the management of hard-to-heal wounds.

CASES

Four patients suffering from difficult-to-heal wounds were treated with the autologous ointment. Within 2 to 8 weeks, all wounds healed completely with no signs of infection or functional impairment of the affected limbs. No adverse events were reported.

CONCLUSION

Randomized and controlled trials are needed to determine the clinical efficacy of the autologous ointment. Nevertheless, results from this multiple case series indicate that this approach may be useful for accelerating the re-epithelization of difficult-to-heal wounds.