Diabetic wound regeneration using peptide-modified hydrogels to target re-epithelialization

Dynamic hydrogels for biofabrication: A review

Reversibly crosslinked dynamic hydrogels have emerged as a significant material platform for biomedical applications owing to their distinctive time-dependent characteristics, including shear-thinning, self-healing, stress relaxation, and creep. These physical properties permit the use of dynamic hydrogels as injectable carriers or three-dimensional printable bioinks. It is noteworthy that matrix dynamics can serve as physical cues that stimulate cellular processes. Therefore, dynamic hydrogels are preferred for tissue engineering and biofabrication, which seek to create functional tissue constructs that require regulation of cellular processes. This review summarizes the critical biophysical properties of dynamic hydrogels, various cellular processes and related mechanisms triggered by hydrogel dynamics, particularly in three-dimensional culture scenarios. Subsequently, we present an overview of advanced biofabrication techniques, particularly 3D bioprinting, of dynamic hydrogels for the large-scale production of tissue and organ engineering models. This review presents an overview of the strategies that can be used to expand the range of applications of dynamic hydrogels in biofabrication, while also addressing the challenges and opportunities that arise in the field. This review highlights the importance of matrix dynamics in regulating cellular processes and elucidates strategies for leveraging them in the context of biofabrication.

Advances in Designer Materials for Chronic Wound Healing

Significance: Nonhealing or chronic wounds represent a significant and growing global health concern, imposing substantial burdens on individuals, health care systems, and economies worldwide. Although the standard-of-care treatment involves the application of wound dressings, most dressing materials are not specifically designed to address the pathological processes underlying chronic wounds. This review highlights recent advances in biomaterial design tailored to chronic wound healing. Recent Advances: Chronic wounds are characterized by persistent inflammation, impaired granulation tissue formation, and delayed re-epithelialization. Newly developed designer materials aim to manage reactive oxygen species and extracellular matrix degradation to suppress inflammation while promoting vascularization, cell proliferation, and epithelial migration to accelerate tissue repair. Critical Issues: Designing optimal materials for chronic wounds remains challenging due to the diverse etiology and a multitude of pathological mechanisms underlying chronic wound healing. While designer materials can target specific aberrations, designing a materials approach that restores all aberrant wound-healing processes remains the Holy Grail. Addressing these issues requires a deep understanding of how cells interact with the materials and the complex etiology of chronic wounds. Future Directions: New material approaches that target wound mechanics and senescence to improve chronic wound closure are under development. Layered materials combining the best properties of the approaches discussed in this review will pave the way for designer materials optimized for chronic wound healing.

Current Insight of Peptide-Based Hydrogels for Chronic Wound Healing Applications: A Concise Review

Chronic wounds present a substantial healthcare obstacle, marked by an extended healing period that can persist for weeks, months, or even years. Typically, they do not progress through the usual phases of healing, which include hemostasis, inflammation, proliferation, and remodeling, within the expected timeframe. Therefore, to address the socioeconomic burden in taking care of chronic wounds, hydrogel-based therapeutic materials have been proposed. Hydrogels are hydrophilic polymer networks with a 3D structure which allows them to become skin substitutes for chronic wounds. Knowing that peptides are abundant in the human body and possess distinct biological functionality, activity, and selectivity, their adaptability as peptide-based hydrogels to individual therapeutic requirements has made them a significant potential biomaterial for the treatment of chronic wounds. Peptide-based hydrogels possess excellent physicochemical and mechanical characteristics such as biodegradability and swelling, and suitable rheological properties as well great biocompatibility. Moreover, they interact with cells, promoting adhesion, migration, and proliferation. These characteristics and cellular interactions have driven peptide-based hydrogels to be applied in chronic wound healing.

Chitooligosaccharides promote diabetic wound healing by mediating fibroblast proliferation and migration

Diabetic wounds are notoriously difficult to heal due to impaired cell repair mechanisms, reduced angiogenesis, and a heightened risk of infection. Fibroblasts play a vital role in wound healing by producing extracellular matrix (ECM) components and various growth factors, but their function is inhibited in diabetic wounds. Chitooligosaccharides (COS), intermediate products of chitosan degradation, have shown efficacy in promoting tissue repair, yet their role in diabetic wound healing remains underexplored. In a mouse model of diabetic wounds, COS treatment demonstrated substantial bioactivity in accelerating wound healing by enhancing fibroblast proliferation and migration. Additionally, COS increased collagen III deposition and angiogenesis at the wound sites. The COS also mitigated inflammatory responses by controlling leukocyte infiltration and bacterial infection. Mechanistically, COS regulated fibroblast activity via the PI3K/Akt signaling pathway, providing a novel bioactive material for chronic wound healing.

Design and Applications of Supramolecular Peptide Hydrogel as Artificial Extracellular Matrix

Supramolecular peptide hydrogels (SPHs) consist of peptides containing hydrogelators and functional epitopes, which can first self-assemble into nanofibers and then physically entangle together to form dynamic three-dimensional networks. Their porous structures, excellent bioactivity, and high dynamicity, similar to an extracellular matrix (ECM), have great potential in artificial ECM. The properties of the hydrogel are largely dependent on peptides. The noncovalent interactions among hydrogelators drive the formation of assemblies and further transition into hydrogels, while bioactive epitopes modulate cell-cell and cell-ECM interactions. Therefore, SPHs can support cell growth, making them ideal biomaterials for ECM mimics. This Review outlines the classical molecular design of SPHs from hydrogelators to functional epitopes and summarizes the recent advancements of SPHs as artificial ECMs in nervous system repair, wound healing, bone and cartilage regeneration, and organoid culture. This emerging SPH platform could provide an alternative strategy for developing more effective biomaterials for tissue engineering.

Hybrid Hydrogels of Polyacrylamide and Self-assembly Photodynamic Nanoparticles with Diverse Adhesion for Infected Chronic Wound Healing

The healing of infected wounds is challenging for patients. In this paper, a hybrid hydrogel with strong tissue adhesion, self-healing, and antibiosis without antibiotics was developed as a dressing to promote the healing of infected chronic wounds. Acrylamide (PAM) was polymerized with N,N-methylene bis(acrylamide) (BIS) as the substrate, and self-assembled nanoparticles of carboxymethyl chitosan and chlorin e6 (CMCS/Ce6 NPs) trapped with magnesium (Mg2+) ions were dispersed in the hydrogel substrate. CMCS/Ce6 NPs provided favorable photodynamic antibiosis via the production of reactive oxygen species (ROS) under NIR irradiation. The hybrid hydrogels exhibited excellent self-healing properties, diverse adhesion, and biocompatibility. The in vivo results indicated that the hybrid hydrogel accelerated wound healing significantly via comprehensive factors of photodynamic antibiosis of CMCS/Ce6 NPs, cell proliferation promotion by Mg2+, good bioadhesion, and moisture retention of the PAM hydrogel, which promoted collagen deposition and blood vessel maturation.

A Standardized Mouse Model for Wound Infection with Pseudomonas aeruginosa

Pseudomonas aeruginosa is a highly drug-resistant pathogen known to impair wound healing and provoke inflammatory responses, potentially leading to immune dysregulation. This study aimed to systematically investigate the immune response mechanisms mediated by cytokines following P. aeruginosa infection through the development of a standardized wound model. Kunming mice were selected as experimental subjects and given 8 mm diameter lesions on their backs and inoculated with standard strains PAO1 and PA14. The key parameters assessed included changes in body weight, wound redness and swelling, bacterial dynamics, protein content in wound tissues, immune responses, and pathological alterations. The results demonstrated that pathogen invasion significantly inhibited wound healing, with healing rates in the infected groups (87.5 ± 6.3% and 77.1 ± 3.6%) being notably lower than those in the uninfected control group. P. aeruginosa persisted in the wounds for up to 12 days, with bacterial loads decreasing from 8 log to 2 log. Additionally, there was a marked reduction in the protein content of the wound tissue and an increase in the expression levels of inflammatory factors such as IL-1β and TNF-α. The thickness of granulation tissue and the number of neovessels were significantly lower compared to the uninfected control group. This study establishes a standardized paradigm for creating a mouse model of P. aeruginosa infection in wounds, emphasizing the importance of appropriate mouse strains, uniform wound preparation methods, and moderate inoculation doses for reliable and accurate experimental results. These elements will facilitate the assessment of changes across six key indicators post-infection, providing a foundational data set and technical support for future mechanistic investigations of P. aeruginosa infection and the development of targeted antimicrobial strategies.

Application of Pro-angiogenic Biomaterials in Myocardial Infarction

Biomaterials have potential applications in the treatment of myocardial infarction (MI). These biomaterials have the ability to mechanically support the ventricular wall and to modulate the inflammatory, metabolic, and local electrophysiological microenvironment. In addition, they can play an equally important role in promoting angiogenesis, which is the primary prerequisite for the treatment of MI. A variety of biomaterials are known to exert pro-angiogenic effects, but the pro-angiogenic mechanisms and functions of different biomaterials are complex and diverse, and have not yet been systematically described. This review will focus on the pro-angiogenesis of biomaterials and systematically describe the mechanisms and functions of different biomaterials in promoting angiogenesis in MI.

Review of skin grafting in equine wounds: indications and techniques

Skin grafting is a simple technique that can be performed by equine practitioners to improve cosmetic outcomes in wounds with large skin defects that would not heal functionally or cosmetically with standard wound therapy interventions. Successful skin grafting is not difficult but relies upon appropriate preparation of the wound bed and effective immobilisation of the grafted area after skin graft placement. Prior to grafting, the wound bed should be treated with a moist wound healing dressing to prepare the granulation tissue bed to receive the graft. For best results, skin grafts should be placed in wounds free of infection with healthy granulation tissue, and motion should be reduced in the graft region in the early postoperative period. When successful, skin grafts cover granulation tissue and encourage wound contraction and epithelialisation while decreasing exuberant granulation tissue resulting in a more cosmetic result. This review will advance practitioners' understanding of skin grafting in horses, including graft classification and techniques, donor site selection, recipient site preparation, postoperative management strategies to optimise graft retention and ongoing research in this field.

The Application of Regenerated Silk Fibroin in Tissue Repair

Silk fibroin (SF) extracted from silk is non-toxic and has excellent biocompatibility and biodegradability, making it an excellent biomedical material. SF-based soft materials, including porous scaffolds and hydrogels, play an important role in accurately delivering drugs to wounds, creating microenvironments for the adhesion and proliferation of support cells, and in tissue remodeling, repair, and wound healing. This article focuses on the study of SF protein-based soft materials, summarizing their preparation methods and basic applications, as well as their regenerative effects, such as drug delivery carriers in various aspects of tissue engineering such as bone, blood vessels, nerves, and skin in recent years, as well as their promoting effects on wound healing and repair processes. The authors expect SF soft materials to play an important role in the field of tissue repair.

Dual-Mechanism Peptide SR25 has Broad Antimicrobial Activity and Potential Application for Healing Bacteria-infected Diabetic Wounds

The rise of antibiotic resistance poses a significant public health crisis, particularly due to limited antimicrobial options for the treatment of infections with Gram-negative pathogens. Here, an antimicrobial peptide (AMP) SR25 is characterized, which effectively kills both Gram-negative and Gram-positive bacteria through a unique dual-targeting mechanism without detectable resistance. Meanwhile, an SR25-functionalized hydrogel is developed for the efficient treatment of infected diabetic wounds. SR25 is obtained through genome mining from an uncultured bovine enteric actinomycete named Nonomuraea Jilinensis sp. nov. Investigations reveal that SR25 has two independent cellular targets, disrupting bacterial membrane integrity and restraining the activity of succinate:quinone oxidoreductase (SQR). In a diabetic mice wound infection model, the SR25-incorporated hydrogel exhibits high efficacy against mixed infections of Escherichia coli (E. coli) and methicillin-resistant Staphylococcus aureus (MRSA), accelerating wound healing. Overall, these findings demonstrate the therapeutic potential of SR25 and highlight the value of mining drugs with multiple mechanisms from uncultured animal commensals for combating challenging bacterial pathogens.

Self-Healing Guar Gum-Based Nanocomposite Hydrogel Promotes Infected Wound Healing through Photothermal Antibacterial Therapy

Preventing bacterial infections is a crucial aspect of wound healing. There is an urgent need for multifunctional biomaterials without antibiotics to promote wound healing. In this study, we fabricated a guar gum (GG)-based nanocomposite hydrogel, termed GBTF, which exhibited photothermal antibacterial therapy for infected wound healing. The GBTF hydrogel formed a cross-linked network through dynamic borate/diol interactions between GG and borax, thereby exhibiting simultaneously self-healing, adaptable, and injectable properties. Additionally, tannic acid (TA)/Fe3+ nanocomplexes (NCs) were incorporated into the hydrogel to confer photothermal antibacterial properties. Under the irradiation of an 808 nm near-infrared laser, the TA/Fe3+ NCs in the hydrogel could rapidly generate heat, leading to the disruption of bacterial cell membranes and subsequent bacterial eradication. Furthermore, the hydrogels exhibited good cytocompatibility and hemocompatibility, making them a precandidate for preclinical and clinical applications. Finally, they could significantly promote bacteria-infected wound healing by reducing bacterial viability, accelerating collagen deposition, and promoting epithelial remodeling. Therefore, the multifunctional GBTF hydrogel, which was composed entirely of natural substances including guar gum, borax, and polyphenol/ferric ion NCs, showed great potential for regenerating infected skin wounds in clinical applications.

Passion fruit (Passiflora edulis Sims) by-products as a source of bioactive compounds for non-communicable disease prevention: extraction methods and mechanisms of action: a systematic review

Introduction

The review titled Passion fruit by-products as a source of bioactive compounds for non-communicable disease prevention: extraction methods and mechanisms provide valuable insights into the health benefits and industrial applications of passion fruit waste. Passion fruits are a tropical and subtropical vine species, which produces edible fruits. Many food product types can be made from passion fruits. However, during passion fruit processing, large amounts of waste are released in to the environment. This review focuses on extraction methods of bioactive compounds from passion fruit by-products such as leaves, peels, seeds, and bagasse.

Methods

This comprehensive review focuses on the bioactive compounds present in passion fruit by-products, emphasis on their mechanisms of action on non-communicable diseases. It also provides a detailed analysis of the extraction methods used to obtain these bioactive compounds, their potential industrial applications, and the factors that affect extraction efficiency.

Results

This review encourages further research and innovation in utilization of passion fruit waste as a source of bioactive compounds for non- communicable disease prevention and their mechanisms of action. This can advance the circular economy. It also highlights the importance of sustainable and green extraction methods, which have gained attention due to environmental concerns.

Discussion

Unlike previous reviews, this comprehensive article explores the potential health benefits of multiple passion fruit waste products. It also examines the possible applications of these extracts for industrial goods such as food additives, colorants, nutraceuticals, natural antioxidants, and antimicrobial agents. Overall, it contributes new information emphasizing the potential of passion fruit by-products as a source of bioactive, and the findings have implications for the scientific community and industry, promoting a deeper understanding of the health benefits and sustainable practices associated with passion fruit waste utilization.

The Best Protocol to Treat Equine Skin Wounds by Second Intention Healing: A Scoping Review of the Literature

Equine skin wound treatment continues to be a challenge for veterinarians. Despite being a frequent practice, it remains difficult to choose an evidence-based treatment protocol. This study aimed to comprehensively explore the literature and provide a scoping review of therapeutic strategies for equine skin wounds and identify knowledge gaps and opportunities for future research. This review was conducted using specific criteria to select literature that described methods to manage second intention wound healing. After removing duplicates and screening papers for suitability, 81 manuscripts were included for data extraction. Of these, 59 articles were experimental studies, 10 were case reports, 9 were case series, and 3 were clinical studies. The most frequent wound location was the distal limbs. Macroscopic assessment was the main tool used to evaluate treatment effectiveness. All of the case reports, case series, and clinical studies reported positive outcomes with regard to the treatment used, while only 36% of the experimental studies found significant healing improvement in treated wounds compared to control groups. It was found that there are many treatments that have exhibited controversial results, and there exists a lack of evidence for the adoption of specific treatment protocols.

Fabrication and evaluation of Dillenia indica-carrageenan blend hybrid superporous hydrogel reinforced with green synthesized MgO nanoparticles as an effective wound dressing material

An unexplored hybrid superporous hydrogel (MHSPH) of Dillenia indica fruit mucilage (DIFM) and carrageenan blend embedded with green synthesized magnesium oxide nanoparticles (MNPs) is utilized as an effective wound dressing material with appreciable mechanical strength in murine model. The prepared MNPs and the optimized MHSPH were characterized using X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FT- IR) spectroscopy. Size, zeta potential and morphology of MNPs was assessed using Dynamic light scattering technique (DLS) and field-emission scanning electron microscopy (FESEM) respectively. The MHSPH grades were further optimized using swelling study in phosphate buffer solution at pH 1.2, 7.0, and 8. Both MNPs and the optimized grade of MHSPH were evaluated based on hemolysis assay, and protein denaturation assays indicating them to be safe for biological use. Acute toxicity studies of the optimized MHSPH on Zebra fish model, revealed no observable toxic effect on the gill cells. Wound healing in Swiss albino mice with application of optimized grade of MHSPH took only 11 days for healing when compared to control mice where healing took 14 days, thus concluding that MHSPH as an effective dressing material as well as tissue regrowth scaffold.

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.

Long noncoding RNA XIST promotes cell proliferation and migration in diabetic foot ulcers through the miR-126-3p/EGFR axis

BACKGROUND

The prevalence of diabetic foot ulcers (DFUs) has caused serious harm to human health. To date, a highly effective treatment is lacking. Long noncoding RNA X-inactive specific transcript (lncRNA XIST) has been the subject of mounting research studies, all of which have found that it serves as a protective factor against certain diseases; however, its function in DFUs is not entirely understood. This study was performed to determine the importance of the lncRNA XIST in the pathogenesis and biological function of DFUs.

METHODS

Diabetic ulcer skin from rats was analysed using haematoxylin-eosin (HE), Masson's trichrome, and immunohistochemistry (IHC) staining. The differences in the expression of genes and proteins were examined with real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting. Next, the interaction was verified with a dual luciferase gene reporter assay. In addition, CCK-8, Transwell, and wound healing assays were used to assess the proliferation and migration of HaCaT cells.

RESULTS

The lncRNA XIST and epidermal growth factor receptor (EGFR) were downregulated, while microRNA-126-3p (miR-126-3p) was increased in diabetic ulcer rat skin tissues and high glucose-induced HaCaT cells. In addition, we found that the lncRNA XIST binds to miR-126-3p and that EGFR is directly targeted by miR‑126‑3p. Silencing XIST contributed to upregulated miR-126-3p expression, thus lowering EGFR levels and inhibiting the proliferative and migratory abilities of high glucose-treated HaCaT cells; however, the miR-126-3p inhibitor and overexpression of EGFR reversed this effect.

CONCLUSION

Decreased lncRNA XIST expression inhibits the proliferative and migratory abilities of high glucose-induced HaCaT cells by modulating the miR-126-3p/EGFR axis, causing delayed wound healing.

Advances of regenerated and functionalized silk biomaterials and application in skin wound healing

The cocoon silk of silkworms (Bombyx mori) has multiple potential applications in biomedicine due to its good biocompatibility, mechanical properties, degradability, and plasticity. Numerous studies have confirmed that silk material dressings are more effective than traditional ones in the skin wound healing process. Silk material research has recently moved toward functionalized biomaterials and achieved remarkable results. Herein, we summarize the recent advances in functionalized silk materials and their efficacy in skin wound healing. In particular, transgenic technology has realized the specific expression of human growth factors in the silk glands of the silkworms, which lays the foundation for fabricating novel and low-cost functionalized materials. Without a green and safe preparation process, the best raw silk materials cannot be made into medically safe products. Therefore, we provide an overview of green and gentle approaches for silk degumming and silk sericin (SS) extraction. Moreover, we summarize and discuss the processing methods of silk fibroin (SF) and SS materials and their potential applications, such as burns, diabetic wounds, and other wounds. This review aims to enhance our understanding of new advances and directions in silk materials and guide future biomedical research.

Multifunctional Hydrogels for the Healing of Diabetic Wounds

The healing of diabetic wounds is hindered by various factors, including bacterial infection, macrophage dysfunction, excess proinflammatory cytokines, high levels of reactive oxygen species, and sustained hypoxia. These factors collectively impede cellular behaviors and the healing process. Consequently, this review presents intelligent hydrogels equipped with multifunctional capacities, which enable them to dynamically respond to the microenvironment and accelerate wound healing in various ways, including stimuli -responsiveness, injectable self-healing, shape -memory, and conductive and real-time monitoring properties. The relationship between the multiple functions and wound healing is also discussed. Based on the microenvironment of diabetic wounds, antibacterial, anti-inflammatory, immunomodulatory, antioxidant, and pro-angiogenic strategies are combined with multifunctional hydrogels. The application of multifunctional hydrogels in the repair of diabetic wounds is systematically discussed, aiming to provide guidelines for fabricating hydrogels for diabetic wound healing and exploring the role of intelligent hydrogels in the therapeutic processes.

Simvastatin-Releasing Nanofibrous Peptide Hydrogels for Accelerated Healing of Diabetic Wounds

Wound healing is one of the major global health concerns in diabetic patients. Simvastatin (SMV) is a poorly soluble oral cholesterol-lowering drug that may aid diabetic wound healing. In the current study, a thixotropic peptide hydrogel of Fmoc-diphenylalanine (FmocFF) containing SMV was designed to accelerate skin wound healing effectively and safely in diabetic mice. FmocFF hydrogels were prepared at various concentrations by using the solvent-triggering technique and characterized by spectroscopic methods such as attenuated total reflection Fourier transform infrared (FT-IR) spectroscopy and fluorimetry. Mechanical behaviors were explored by oscillatory rheology. In model mice, the regenerative potential of the FmocFF-SMV hydrogel was evaluated in terms of wound contraction and closure, tissue regeneration, acute and chronic inflammation, granulation, and re-epithelization. The results showed that FmocFF-SMV hydrogels had an entangled nanofibrous microstructure and shear-thinning characteristics. FmocFF-SMV demonstrated a sustained drug release over 7 days. Compared to the unloaded FmocFF hydrogel, treatment with FmocFF-SMV led to superior diabetic wound recovery and reduced inflammation. Therefore, the utilization of the sustained-release FmocFF-SMV hydrogel formulation could become an attractive choice for topical wound therapy in diabetes patients.

Oxidative Stimuli-Responsive "Pollen-Like" Exosomes from Silver Nanoflowers Remodeling Diabetic Wound Microenvironment for Accelerating Wound Healing

The hostile oxidative wound microenvironment, defective angiogenesis, and uncontrolled release of therapeutic factors are major challenges in improving the diabetic wound healing. Herein, adipose-derived-stem-cell-derived exosomes (Exos) are first loaded into Ag@bovine serum albumin (BSA) nanoflowers (Exos-Ag@BSA NFs) to form a protective "pollen-flower" delivery structure, which are further encapsulated into the injectable collagen (Col) hydrogel (Exos-Ag@BSA NFs/Col) for concurrent remodeling of the oxidative wound microenvironment and precise release of Exos. The Exos-Ag@BSA NFs can selectively dissociate in an oxidative wound microenvironment, which triggers sustained release of Ag ions (Ag+ ) and cascades controllable release of "pollen-like" Exos at the target site, thus protecting Exos from oxidative denaturation. Such a wound-microenvironment-activated release property of Ag+ and Exos effectively eliminates bacteria and promotes the apoptosis of impaired oxidative cells, resulting in improved regenerative microenvironment. Additionally, Exos-Ag@BSA NFs/Col markedly accelerates wound healing and regeneration in vivo in a diabetic murine silicone-splinted excisional wound model by promoting blood perfusion, tissue granulation, collagen deposition, neovascularization, angiogenesis, and re-epithelization. It is anticipated that this work will inspire the development of more delicate and disease-specific therapeutic systems for clinical wound management.

A Review of Metal Nanoparticles Embedded in Hydrogel Scaffolds for Wound Healing In Vivo

An evolving field, nanotechnology has made its mark in the fields of nanoscience, nanoparticles, nanomaterials, and nanomedicine. Specifically, metal nanoparticles have garnered attention for their diverse use and applicability to dressings for wound healing due to their antimicrobial properties. Given their convenient integration into wound dressings, there has been increasing focus dedicated to investigating the physical, mechanical, and biological characteristics of these nanoparticles as well as their incorporation into biocomposite materials, such as hydrogel scaffolds for use in lieu of antibiotics as well as to accelerate and ameliorate healing. Though rigorously tested and applied in both medical and non-medical applications, further investigations have not been carried out to bring metal nanoparticle-hydrogel composites into clinical practice. In this review, we provide an up-to-date, comprehensive review of advancements in the field, with emphasis on implications on wound healing in in vivo experiments.

Thermosensitive and antioxidant wound dressings capable of adaptively regulating TGFβ pathways promote diabetic wound healing

Various therapies have been utilized for treating diabetic wounds, yet current regiments do not simultaneously address the key intrinsic causes of slow wound healing, i.e., abnormal skin cell functions (particularly migration), delayed angiogenesis, and chronic inflammation. To address this clinical gap, we develop a wound dressing that contains a peptide-based TGFβ receptor II inhibitor (PTβR2I), and a thermosensitive and reactive oxygen species (ROS)-scavenging hydrogel. The wound dressing can quickly solidify on the diabetic wounds following administration. The released PTβR2I inhibits the TGFβ1/p38 pathway, leading to improved cell migration and angiogenesis, and decreased inflammation. Meanwhile, the PTβR2I does not interfere with the TGFβ1/Smad2/3 pathway that is required to regulate myofibroblasts, a critical cell type for wound healing. The hydrogel's ability to scavenge ROS in diabetic wounds further decreases inflammation. Single-dose application of the wound dressing significantly accelerates wound healing with complete wound closure after 14 days. Overall, using wound dressings capable of adaptively modulating TGFβ pathways provides a new strategy for diabetic wound treatment.

Structural and biological engineering of 3D hydrogels for wound healing

Chronic wounds have become one of the most important issues for healthcare systems and are a leading cause of death worldwide. Wound dressings are necessary to facilitate wound treatment. Engineering wound dressings may substantially reduce healing time, reduce the risk of recurrent infections, and reduce the disability and costs associated. In the path of engineering of an ideal wound dressing, hydrogels have played a leading role. Hydrogels are 3D hydrophilic polymeric structures that can provide a protective barrier, mimic the native extracellular matrix (ECM), and provide a humid environment. Due to their advantages, hydrogels (with different architectural, physical, mechanical, and biological properties) have been extensively explored as wound dressing platforms. Here we describe recent studies on hydrogels for wound healing applications with a strong focus on the interplay between the fabrication method used and the architectural, mechanical, and biological performance achieved. Moreover, we review different categories of additives which can enhance wound regeneration using 3D hydrogel dressings. Hydrogel engineering for wound healing applications promises the generation of smart solutions to solve this pressing problem, enabling key functionalities such as bacterial growth inhibition, enhanced re-epithelialization, vascularization, improved recovery of the tissue functionality, and overall, accelerated and effective wound healing.

Combined effect of SDF-1 peptide and angiogenic cues in co-axial PLGA/gelatin fibers for cutaneous wound healing in diabetic rats

Skin regeneration is hindered by poor vascularization, prolonged inflammation, and excessive scar tissue formation, which necessitate newer strategies to simultaneously induce blood vessel regeneration, resolve inflammation, and induce host cell recruitment. Concurrent deployment of multiple biological cues to realize synergistic reparative effects may be an enticing avenue for wound healing. Herein, we simultaneously deployed SDF (stromal cell-derived factor)- 1α, VEGF (vascular endothelial growth factor)-binding peptide (BP), and GLP (glucagon like peptide)- 1 analog, liraglutide (LG) in core/shell poly(L-lactide-co-glycolide)/gelatin fibers to harness their synergistic effects for skin repair in healthy as well as diabetic wound models in rats. Microscopic techniques, such as SEM and TEM revealed fibrous and core/shell type morphology of membranes. Boyden chamber assay and scratch-wound assay displayed significant migration of HUVECs (human umbilical vein endothelial cells) in SDF-1α containing fibers. Subcutaneous implantation of membranes revealed higher cellular infiltration in SDF-1α loaded fibers, especially, those which were co-loaded with LG or BP. Implantation of membranes in an excisional wound model in healthy rats further showed significant and rapid wound closure in dual cues loaded groups as compared to control or single cue loaded groups. Similarly, the implantation of dressings in type 2 diabetes rat model revealed fast healing, skin appendages regeneration, and blood vessel regeneration in dual cues loaded fibers (SDF-1α/LG, SDF-1α/BP). Taken together, core/shell type fibers containing bioactive peptides significantly promoted wound repair in healthy as well as diabetic wound models in rats.

Multifunctional Self-Assembled Peptide Hydrogels for Biomedical Applications

Self-assembly is a growth mechanism in nature to apply local interactions forming a minimum energy structure. Currently, self-assembled materials are considered for biomedical applications due to their pleasant features, including scalability, versatility, simplicity, and inexpensiveness. Self-assembled peptides can be applied to design and fabricate different structures, such as micelles, hydrogels, and vesicles, by diverse physical interactions between specific building blocks. Among them, bioactivity, biocompatibility, and biodegradability of peptide hydrogels have introduced them as versatile platforms in biomedical applications, such as drug delivery, tissue engineering, biosensing, and treating different diseases. Moreover, peptides are capable of mimicking the microenvironment of natural tissues and responding to internal and external stimuli for triggered drug release. In the current review, the unique characteristics of peptide hydrogels and recent advances in their design, fabrication, as well as chemical, physical, and biological properties are presented. Additionally, recent developments of these biomaterials are discussed with a particular focus on their biomedical applications in targeted drug delivery and gene delivery, stem cell therapy, cancer therapy and immune regulation, bioimaging, and regenerative medicine.

Angiopoietin-1 derived peptide hydrogel promotes molecular hallmarks of regeneration and wound healing in dermal fibroblasts

By providing an ideal environment for healing, biomaterials can be designed to facilitate and encourage wound regeneration. As the wound healing process is complex, there needs to be consideration for the cell types playing major roles, such as fibroblasts. As a major cell type in the dermis, fibroblasts have a large impact on the processes and outcomes of wound healing. Prevopisly, conjugating the angiopoietin-1 derived Q-peptide (QHREDGS) to a collagen-chitosan hydrogel created a biomaterial with in vivo success in accelerating wound healing. This study utilized solvent cast Q-peptide conjugated collagen-chitosan seeded with fibroblast monolayers to investigate the direct impact of the material on this major cell type. After 24 h, fibroblasts had a significant change in release of anti-inflammatory, pro-healing, and ECM deposition cytokines, with demonstrated immunomodulatory effects on macrophages and upregulated expression of critical wound healing genes.

Carboxymethyl cellulose/sericin-based hydrogels with intrinsic antibacterial, antioxidant, and anti-inflammatory properties promote re-epithelization of diabetic wounds in rats

Diabetic wound healing encounters significant challenges due to the extreme oxidative stress resulting from excessive inflammation and microbial infections, disrupting the typical cascade of wound healing and thwarting the re-epithelialization of skin tissues. Benefiting from the biological activities of carboxymethyl cellulose (CMC) and sericin, we thus fabricated multifunctional hydrogels of CMC-Sericin. The hydrogel revealed high swelling performance alongside its porous structure. The incorporation of sericin bestowed the CMC-Sericin hydrogels with a prominent capacity to scavenge free radicals and antibacterial activity. In vivo investigations using diabetic full-thickness excision wounds demonstrated the capability of CMC-Sericin dressing to enhance diabetic wounds in rats treated or untreated with insulin concurrently. Furthermore, histopathological examinations manifested the skin tissue regeneration evidenced by the development of skin appendages like hair follicles and collagen deposition after treatment with CMC-Sericin hydrogel. Moreover, the levels of antioxidant parameters, including GSH and SOD, were substantially augmented and associated with a significant diminution in lipid peroxidation, implying a decrease in oxidative stress in the tissues. Beyond that, CMC-Sericin dressing downregulated the pro-inflammatory markers and upregulated the heat shock proteins, indicating the restoration of physiological features in cells. Strikingly, CMC-Sericin dressing remarkably promoted the healing of diabetic wounds without insulin treatment.

Co-assembling of natural drug-food homologous molecule into composite hydrogel for accelerating diabetic wound healing

Diabetic wound healing is a major clinical challenge due to its vulnerability to bacterial infection and the prolonged inflammation in the wound. Traditional dressings for the healing of diabetic wounds are often suffered from unsatisfactory efficacy and frequent dressing changes which may cause secondary damage. Therefore, it is necessary to find a wound dressing that balances material functionality, degradation, safety, and tissue regeneration. Our recent studies demonstrated that gallic acid (GA) could spontaneously form supramolecular hydrogels at a relatively high concentration. However, a single network of GA hydrogel is prone to degradation, poor adhesion, and poor swelling, and may not be suitable for wound healing dressings. In this study, a composite hydrogel (GAK) was constructed by introducing konjac glucomannan (KGM) into the gel system of gallic acid (GA) and applied to promote diabetic wound healing. The composite hydrogel (GAK) with superior surface adhesion, stability, and swelling properties than the single-network of GA hydrogel. Moreover, in vitro experiments showed that GAK hydrogel had excellent biocompatibility and exhibited antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Additionally, the GAK hydrogel could significantly accelerate angiogenesis, collagen deposition, and re-epithelialization during wound healing in diabetic mice, reducing the expression of related inflammatory proteins interleukin-1β (IL-1β), tumor necrosis factor-alpha (TNF-α), and cyclooxygenase-2 (COX-2), and improving the wound closure rate. The findings of this study suggest that this composite hydrogel (GAK) can be an ideal dressing material for accelerating diabetic wound healing.

Antioxidant Silk Fibroin Composite Hydrogel for Rapid Healing of Diabetic Wound

Wound healing is a complex process requiring multiple biological pathways and chemical responses to be activated and synchronized to recover tissue integrity. In normal physiological circumstances, the epidermal barrier restoration process through new tissue formation is highly efficient. However, increased production of reactive oxygen species, attack of pathogenic microorganisms, and high glucose level delay the normal healing process in diabetic patients. The successful treatment of diabetic wounds requires efficient strategies to control oxidative stress, promoting angiogenesis, re-epithelialization, and collagen deposition. In this study, we developed a composite hydrogel for rapid wound healing in diabetic condition by the amalgamation of hypolipidemic property of silk fibroin (SF), antioxidant property of melanin and therapeutic effect of berberine. Studies have revealed that cross-linked mesoporous morphology of hydrogel matrix facilitates slow release of berberine to impart long-term therapeutic effects at wound site. The composite hydrogel formulation is biocompatible, stimulates effective migration of fibroblast cells, and control oxidative stress under in vitro conditions. The hydrogel served as scaffold for tissue re-epithelialization and promotes wound repair in diabetic type I Wistar rat model. This study demonstrates the ability of berberine- loaded SF-melanin composite hydrogel (SFCH) as a potential dressing formulation for wound healing in diabetic conditions. This article is protected by copyright. All rights reserved.

[Effects of methacrylic anhydride gelatin hydrogel loaded with silver and recombinant human basic fibroblast growth factor on deep partial-thickness burn wounds in rabbits]

Objective: To investigate the effects of methacrylic anhydride gelatin (GelMA) hydrogel loaded with silver and recombinant human basic fibroblast growth factor (rh-bFGF) on deep partial-thickness burn wounds in rabbits. Methods: The experimental research method was adopted. Low-concentration GelMA materials, medium-concentration GelMA materials and high-concentration GelMA materials containing different concentrations of methacrylic anhydride (MA) were prepared, after adding photoinitiator, low-concentration GelMA hydrogels, medium-concentration GelMA hydrogels, and high-concentration GelMA hydrogels were obtained, respectively. The nuclear magnetic resonance spectroscopy was performed to detect the hydrogen nuclear magnetic resonance spectra of the above-mentioned three concentrations of GelMA materials, and to calculate the degree of substitution according to the spectrum diagram. The three-dimensional microstructure and pore size of 3 types of above-mentioned GelMA hydrogels were detected by field emission scanning electron microscopy (FESEM), with 9 samples measured. According to the selected concentration of MA, ten kinds of solutions of GelMA with different concentration of silver (silver-containing GelMA) were synthesized, and the silver-containing GelMA solution of each concentration was divided into three parts, and then exposed to ultraviolet light lasting for 20, 25, and 35 s, respectively. After adding photoinitiator,the corresponding silver-containing GelMA hydrogels were obtained. The residual degradation rate of silver-containing GelMA hydrogel with different photocrosslinking times was detected by collagenase degradation method at degradation of 12, 24, 36, and 48 h; and the time required for complete degradation was detected, and the sample number was 5. The inhibition zone diameter of GelMA hydrogel under above screened photocrosslinking times containing 10 concentrations of silver against Staphylococcus aureus was measured to reflect its antibacterial ability, and the sample numbers were all 5. The silver-containing GelMA hydrogel with statistical significance compared with the antibacterial circle diameter of the silver-containing GelMA hydrogel containing the lowest concentration (no silver) was considered as having antibacterial activity. The three-dimensional microstructure and pore size of the silver-containing GelMA hydrogels with antibacterial activity and the lowest drug concentration selected were detected by FESEM, and the sample numbers were all 9. The freeze-dried alone GelMA hydrogel and the freeze-dried silver-containing GelMA hydrogel were soaked in phosphate buffer solution for 24 h, respectively, then the swelling rate of the two GelMA hydrogel were calculated and compared by weighing method, and the sample number was 5. GelMA hydrogel containing silver and rh-bFGF, namely compound hydrogel for short, was prepared according to the preliminary experiment and the above experimental results. The appearance of the composite hydrogel was observed in general, and its three-dimensional microstructure and pore size were detected by FESEM. The deep partial-thickness burn wound was made on the back of 30 rabbits (aged 4-6 months, female half and half). Meanwhile, with the rabbit head as the benchmark, the wounds on the left side of the spine were treated as composite hydrogel treatment group, and the wounds on the right side were treated as gauze control group, and which were treated accordingly. On post injury day (PID) 3, 7, 14, 21, and 28, the healing of wounds in the two groups was observed. On PID 7, 14, 21, and 28, the wound healing area was recorded and the healing rate was calculated, with a sample number of 30. Data were statistically analyzed with analysis of variance for repeated measurement, one-way analysis of variance, and independent sample t test. Results: The substitution degree among low-concentration GelMA materials, medium-concentration GelMA materials, and high-concentration GelMA materials was significantly different (F=1 628.00, P<0.01). The low-concentration GelMA hydrogel had a loose and irregular three-dimensional spatial network structure with a pore size of (60±17) μm; the medium-concentration GelMA hydrogel had a relatively uniform three-dimensional spatial network and pore size with a pore size of (45±13) μm; the high-concentration GelMA hydrogel had the dense and disordered three-dimensional spatial network with a pore size of (25±15) μm, the pore sizes of 3 types of GelMA hydrogels were significantly differences (F=12.20, P<0.01), and medium concentration of MA was selected for the concentration of subsequent materials. The degradability of silver-containing GelMA hydrogels with different concentrations of the same photocrosslinking time was basically same. The degradation residual rates of silver-containing GelMA hydrogels with 20, 25, and 35 s crosslinking time at 12 h were (74.2±1.7)%, (85.3±0.9)%, and (93.2±1.2)%, respectively; the residual rates of degradation at 24 h were (58.3±2.1)%, (65.2±1.8)%, and (81.4±2.6)%, respectively; the residual rates of degradation at 36 h were (22.4±1.9)%, (45.2±1.7)%, and (68.1±1.4)%, respectively; the residual rates of degradation at 48 h were (8.2±1.7)%, (32.4±1.3)%, and (54.3±2.2)%, respectively, and 20, 25, and 30 s photocrosslinking time required for complete degradation of silver-containing GelMA hydrogels were (50.2±2.4), (62.4±1.4), and (72.2±3.2) h, and the difference was statistically significant (F=182.40, P<0.01), 25 s were selected as the subsequent photocrosslinking time. The antibacterial diameters of 10 types of silver-containing GelMA hydrogels against Staphylococcus aureus from low to high concentrations were (2.6±0.4), (2.5±0.4), (3.2±0.4), (12.1±0.7), (14.8±0.7), (15.1±0.5), (16.2±0.6), (16.7±0.5), (16.7±0.4), and (16.7±0.6) mm, respectively, and which basically showed a concentration-dependent increasing trend, and the overall difference was statistically significant (F=428.70, P<0.01). Compared with the silver-containing GelMA hydrogel with the lowest concentration, the antibacterial circle diameters of other silver-containing GelMA hydrogels with antibacterial ability from low to high concentration were significantly increased (with t values of 26.35, 33.84, 43.65, 42.17, 49.24, 55.74, and 43.72, respectively, P<0.01). The silver-containing GelMA hydrogel with the antibacterial diameter of (12.1±0.7) mm had the lowest antibacterial activity against Staphylococcus aureus and the lowest drug loading concentration, and the concentration of silver was selected for the concentration of subsequent materials. The microscopic morphology of the silver-containing GelMA hydrogel containing silver element with a pore size of (45±13) μm had a regular and linear strip-like structure. After soaking for 24 h, the swelling ratio of silver-containing GelMA hydrogel was similar to that of alone GelMA hydrogel. The composite hydrogel was colorless, clear and transparent, and its three-dimensional microstructure was a regular and uniform grid, with a filament network structure inside, and the pore size of (40±21) μm. On PID 3, a large amount of necrotic tissue and exudate of rabbit wound in composite hydrogel group were observed, and scattered scabs, a small amount of necrotic tissue and exudate of rabbit wound in gauze control group were observed. On PID 7, the area of rabbit wound in composite hydrogel group was significantly reduced, and adhesion of rabbit wound and gauze in gauze control group was observed. On PID 14, In composite hydrogel group, the rabbit wound surface was ruddy, and the growth of granulation tissue was observed, and in gauze control group, the rabbit wound base was pale, and the blood supply was poor. On PID 21, the rabbit wounds in composite hydrogel group healed completely, and rabbit wound in gauze control group had healing trend. On PID 28, new hair could be seen on rabbit wound surface in composite hydrogel group; oval wound of rabbit in gauze control group still remained. On PID 7, 14, 21, and 28, the wound healing areas of rabbit in composite hydrogel group were significantly larger than those in gauze control group (with t values of 2.24, 4.43, 7.67, and 7.69, respectively, P<0.05 or P<0.01). Conclusions: The medium-concentration GelMA hydrogel has good physical and chemical properties in terms of swelling and degradability. The screened silver-containing GelMA hydrogels had the lowest antibacterial activity and the lowest drug loading concentration. Composite hydrogel can significantly shorten the healing time of deep partial-thickness burn wounds in rabbits.

Extracellular vesicles enriched with an endothelial cell pro-survival microRNA affects skin tissue regeneration

Endothelial cell (EC) activity is essential for tissue regeneration in several (patho)physiological contexts. However, our capacity to deliver in vivo biomolecules capable of controlling EC fate is relatively limited. Here, we screened a library of microRNA (miR) mimics and identified 25 miRs capable of enhancing the survival of ECs exposed to ischemia-mimicking conditions. In vitro, we showed that miR-425-5p, one of the hits, was able to enhance EC survival and migration. In vivo, using a mouse Matrigel plug assay, we showed that ECs transfected with miR-425-5p displayed enhanced survival compared with scramble-transfected ECs. Mechanistically, we showed that miR-425-5p modulated the PTEN/PI3K/AKT pathway and inhibition of miR-425-5p target genes (DACH1, PTEN, RGS5, and VASH1) phenocopied the pro-survival. For the in vivo delivery of miR-425-5p, we modulated small extracellular vesicles (sEVs) with miR-425-5p and showed, in vitro, that miR-425-5p-modulated sEVs were (1) capable of enhancing the survival of ECs exposed to ischemia-mimic conditions, and (2) efficiently internalized by skin cells. Finally, using a streptozotocin-induced diabetic wound healing mouse model, we showed that, compared with miR-scrambled-modulated sEVs, topical administration of miR-425-5p-modulated sEVs significantly enhanced wound healing, a process mediated by enhanced vascularization and skin re-epithelialization.

Bioactive Injectable Hydrogel Dressings for Bacteria-Infected Diabetic Wound Healing: A "Pull-Push" Approach

Chronic diabetic wound healing remains a challenge due to the existence of excessive danger molecules and bacteria in the inflammatory microenvironment. There is an urgent need for advanced wound dressings that target both inflammation and infection. Here, a bioactive hydrogel without loading any anti-inflammatory ingredients is rationally designed to achieve a "Pull-Push" approach for efficient and safe bacteria-infected diabetic wound healing by integrating danger molecule scavenging (Pull) with antibiotic delivery (Push) in the inflammatory microenvironment. The cationic hydrogel, termed the OCMC-Tob/PEI hydrogel, is fabricated by the conjugation of polyethylenimine (PEI) and tobramycin (Tob) on an oxidized carboxymethyl cellulose (OCMC) backbone via the Schiff base reaction with injectable, self-healing, and biocompatible properties. The OCMC-Tob/PEI hydrogel not only displays the remarkable capability of capturing multiple negatively charged danger molecules (e.g., cell-free DNA, lipopolysaccharides, and tumor necrosis factor-α) to ameliorate anti-inflammation effects but also achieves controllable long-term antibacterial activity by the pH-sensitive release of Tob. Consequently, this multifunctional hydrogel greatly expedites the wound closure rate with combined anti-inflammation and anti-infection effects on Pseudomonas aeruginosa-infected diabetic wounds. Our work provides a highly versatile treatment approach for chronic diabetic wounds and a promising dressing for regenerative medicine.

Biodegradable polyurethane scaffolds in regenerative medicine: Clinical translation review

Early explorations of tissue engineering and regenerative medicine concepts commonly utilized simple polyesters such as polyglycolide, polylactide, and their copolymers as scaffolds. These biomaterials were deemed clinically acceptable, readily accessible, and provided processability and a generally known biological response. With experience and refinement of approaches, greater control of material properties and integrated bioactivity has received emphasis and a broadened palette of synthetic biomaterials has been employed. Biodegradable polyurethanes (PUs) have emerged as an attractive option for synthetic scaffolds in a variety of tissue applications because of their flexibility in molecular design and ability to fulfill mechanical property objectives, particularly in soft tissue applications. Biodegradable PUs are highly customizable based on their composition and processability to impart tailored mechanical and degradation behavior. Additionally, bioactive agents can be readily incorporated into these scaffolds to drive a desired biological response. Enthusiasm for biodegradable PU scaffolds has soared in recent years, leading to rapid growth in the literature documenting novel PU chemistries, scaffold designs, mechanical properties, and aspects of biocompatibility. Despite the enthusiasm in the field, there are still few examples of biodegradable PU scaffolds that have achieved regulatory approval and routine clinical use. However, there is a growing literature where biodegradable PU scaffolds are being specifically developed for a wide range of pathologies and where relevant pre-clinical models are being employed. The purpose of this review is first to highlight examples of clinically used biodegradable PU scaffolds, and then to summarize the growing body of reports on pre-clinical applications of biodegradable PU scaffolds.

Self-Assembling Peptide-Based Hydrogels for Wound Tissue Repair

Wound healing is a long-term, multistage biological process that includes hemostasis, inflammation, proliferation, and tissue remodeling and requires intelligent designs to provide comprehensive and convenient treatment. The complexity of wounds has led to a lack of adequate wound treatment materials, which must systematically regulate unique wound microenvironments. Hydrogels have significant advantages in wound treatment due to their ability to provide spatiotemporal control over the wound healing process. Self-assembling peptide-based hydrogels are particularly attractive due to their innate biocompatibility and biodegradability along with additional advantages including ligand-receptor recognition, stimulus-responsive self-assembly, and the ability to mimic the extracellular matrix. The ability of peptide-based materials to self-assemble in response to the physiological environment, resulting in functionalized microscopic structures, makes them conducive to wound treatment. This review introduces several self-assembling peptide-based systems with various advantages and emphasizes recent advances in self-assembling peptide-based hydrogels that allow for precise control during different stages of wound healing. Moreover, the development of multifunctional self-assembling peptide-based hydrogels that can regulate and remodel the wound immune microenvironment in wound therapy with spatiotemporal control has also been summarized. Overall, this review sheds light on the future clinical and practical applications of self-assembling peptide-based hydrogels.

Thy-1 (CD90), Integrins and Syndecan 4 are Key Regulators of Skin Wound Healing

Acute skin wound healing is a multistage process consisting of a plethora of tightly regulated signaling events in specialized cells. The Thy-1 (CD90) glycoprotein interacts with integrins and the heparan sulfate proteoglycan syndecan 4, generating a trimolecular complex that triggers bi-directional signaling to regulate diverse aspects of the wound healing process. These proteins can act either as ligands or receptors, and they are critical for the successful progression of wound healing. The expression of Thy-1, integrins, and syndecan 4 is controlled during the healing process, and the lack of expression of any of these proteins results in delayed wound healing. Here, we review and discuss the roles and regulatory events along the stages of wound healing that support the relevance of Thy-1, integrins, and syndecan 4 as crucial regulators of skin wound healing.

Topical gel-based biomaterials for the treatment of diabetic foot ulcers

Diabetic foot ulcers (DFUs) are a devastating ailment for many diabetic patients with increasing prevalence and morbidity. The complex pathophysiology of DFU wound environments has made finding effective treatments difficult. Standard wound care treatments have limited efficacy in healing these types of chronic wounds. Topical biomaterial gels have been developed to implement novel treatment approaches to improve therapeutic effects and are advantageous due to their ease of application, tunability, and ability to improve therapeutic release characteristics. Here, we provide an updated, comprehensive review of novel topical biomaterial gels developed for treating chronic DFUs. This review will examine preclinical data for topical gel treatments in diabetic animal models and clinical applications, focusing on gels with protein/peptides, drug, cellular, herbal/antioxidant, and nano/microparticle approaches. STATEMENT OF SIGNIFICANCE: By 2050, 1 in 3 Americans will develop diabetes, and up to 34% of diabetic patients will develop a diabetic foot ulcer (DFU) in their lifetime. Current treatments for DFUs include debridement, infection control, maintaining a moist wound environment, and pressure offloading. Despite these interventions, a large number of DFUs fail to heal and are associated with a cost that exceeds $31 billion annually. Topical biomaterials have been developed to help target specific impairments associated with DFU with the goal to improve healing. A summary of these approaches is needed to help better understand the current state of the research. This review summarizes recent research and advances in topical biomaterials treatments for DFUs.

The Antibacterial and Anti-biofilm Traits of the Novel BMAP-27-Melittin Conjugated Peptide Nanoparticle Against Streptococcus mutans: Clinical Isolates from Oral Cavity

BACKGROUND & OBJECTIVE

The spread and development of drug-resistant bacterial strains has prompted the hunt for novel antibacterial polypeptides undergoing conformational changes to confer rapid bactericidal effects. The aim of this study was to evaluate the effect of novel BMAP27-Melittin conjugated peptide- nanoparticle (NP) against Streptococcus mutans as the primary pathogen from subgingival plaques.

METHODS

Sixty subgingival plaque samples were collected, and 39 S. mutans isolates were identified. The BMAP27-Melittin conjugated peptide was purchased from GenScript Company, USA. Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), Biofilm Inhibitory Concentration (BIC), and Biofilm Eradication Concentration (BEC) of BMAP27-Melittin-NP were calculated using the microtiter method.

RESULTS

Thirty-nine infected subjects were reported, including 24 males and 15 females (P=0.299). MIC, MBC, BIC, and BEC of BMAP27-Melittin-NP against S. mutans were 1.8, 2.9, 2.1, and 3.8μg/mL, respectively. The mean MBC, BEC, and BIC values were significantly lower among clinical isolates than S. mutans ATCC 35688 standard strain (P=0.032, 0.001, and 0.001, respectively).

CONCLUSION

BMAP27-Melittin-NP demonstrated significant antibacterial and anti-biofilm effects against clinical isolates of S. mutans which can be considered a promising compound to prevent or treat dental caries and eradicate the oral infections.

Injectable self-healing ceria-based nanocomposite hydrogel with ROS-scavenging activity for skin wound repair

Excessive reactive oxygen species (ROS) in the injured skin may impede the wound repair and skin regeneration. Herein, we develop an injectable self-healing ceria-based nanocomposite hydrogel with ROS-scavenging activity to accelerate wound healing. The nanocomposite hydrogels were successfully prepared by coating cerium oxide nanorods with polyethylenimine and crosslinked with benzaldehyde-terminated F127 (F127-CHO) through the dynamic Schiff-base reaction (FVEC hydrogel). The results showed that the FVEC hydrogel possessed the good thermosensitivity, injectability, self-healing ability and ROS scavenging activity. The subcutaneous implantation experiments in mice confirmed that FVEC hydrogels are biocompatible and biodegradable in vivo. The full-thickness skin wound studies showed that FVEC hydrogel could significantly enhance the wound healing and epithelium regeneration with the formation of hair follicle and adipocyte tissue. This work provides a new strategy for the development of multifunctional Ce-based nanocomposite hydrogel for full-thickness skin wound healing and regeneration.

Roles of cutaneous cell-cell communication in wound healing outcome: An emphasis on keratinocyte-fibroblast crosstalk

Tissue repair is a very complex event and involves a continuously orchestrated sequence of signals and responses from platelets, fibroblasts, epithelial, endothelial and immune cells. The details of interaction between these signals, which are mainly growth factors and cytokines, have been widely discussed. However, it is still not clear how activated cells at wound sites lessen their activities after epithelialization is completed. Termination of the wound healing process requires a fine balance between extracellular matrix (ECM) deposition and degradation. Maintaining this balance requires highly accurate epithelial-mesenchymal communication and correct information exchange between keratinocytes and fibroblasts. As it has been reported in the literature, a disruption in epithelialization during the process of wound healing increases the frequency of developing chronic wounds or fibrotic conditions, as seen in a variety of clinical cases. Conversely, the potential stop signal for wound healing should have a regulatory role on both ECM synthesis and degradation to reach a successful wound healing outcome. This review briefly describes the potential roles of growth factors and cytokines in controlling the early phase of wound healing and predominantly explores the role of releasable factors from epithelial-mesenchymal interaction in controlling during and the late stage of the healing process. Emphasis will be given on the crosstalk between keratinocytes and fibroblasts in ECM modulation and the healing outcome following a brief discussion of the wound healing initiation mechanism. In particular, we will review the termination of acute dermal wound healing, which frequently leads to the development of hypertrophic scarring.

Rational Design of Peptide-based Smart Hydrogels for Therapeutic Applications

Peptide-based hydrogels have captivated remarkable attention in recent times and serve as an excellent platform for biomedical applications owing to the impressive amalgamation of unique properties such as biocompatibility, biodegradability, easily tunable hydrophilicity/hydrophobicity, modular incorporation of stimuli sensitivity and other functionalities, adjustable mechanical stiffness/rigidity and close mimicry to biological molecules. Putting all these on the same plate offers smart soft materials that can be used for tissue engineering, drug delivery, 3D bioprinting, wound healing to name a few. A plethora of work has been accomplished and a significant progress has been realized using these peptide-based platforms. However, designing hydrogelators with the desired functionalities and their self-assembled nanostructures is still highly serendipitous in nature and thus a roadmap providing guidelines toward designing and preparing these soft-materials and applying them for a desired goal is a pressing need of the hour. This review aims to provide a concise outline for that purpose and the design principles of peptide-based hydrogels along with their potential for biomedical applications are discussed with the help of selected recent reports.

In vitro dielectrophoresis of HEK cell migration for stimulating chronic wound epithelialization

This article describes a dielectrophoresis (DEP)-based simulation and experimental study of human epidermal keratinocyte (HEK) cells for wounded skin cell migration toward rapid epithelialization. MyDEP is a standalone software designed specifically to study dielectric particles and cell response to an alternating current (AC) electric field. This method demonstrated that negative dielectrophoresis (N_DEP ) occurs in HEK cells at a wide frequency range in highly conductive medium. The finite element method was used to characterize particle trajectory based on DEP and drag force. The performance of the system was assessed using HEK cells in a highly conductive EpiLife suspending medium. The DEP experiment was performed by applying sinusoidal wave AC potential at the peak-to-peak voltage of 10 V in a tapered aluminum microelectrode array from 100 kHz to 1 MHz. We experimentally observed the occurrence of NDEP, which attracted HEK cells toward the local electric field minima in the region of interest. The DIPP-MotionV software was used to track cell migration in the prerecorded video via an automatic marker and estimate the average speed and acceleration of the cells. The results showed that HEK cell migration was accomplished approximately at 6.43 μm/s at 100 kHz with 10 V, and F_DEP caused the cells to migrate and align at the target position, which resulted in faster wound closures because of the application of an electric field frequency to HEK cells in random locations.

A Mg2+/polydopamine composite hydrogel for the acceleration of infected wound healing

Bacterial infection is a vital factor to delay the wound healing process. The antibiotics abuse leads to drug resistance of some pathogenic bacteria. Non-antibiotic-dependent multifunctional biomaterials with accelerated wound healing performance are urgently desired. Herein, we reported a composite antibacterial hydrogel PDA-PAM/Mg²⁺ that shows excellent self-healing and tissue adhesive property, and photothermal antibacterial functions for accelerating wound healing. The gel was composed of polyacrylamide (PAM), polydopamine (PDA), and magnesium (Mg²⁺) and prepared via a two-step procedure: an alkali-induced dopamine pre-polymerization and followed radical polymerization process. The composite gel shows excellent tissue adhesiveness and Mg²⁺-synergized photothermal antibacterial activity, inducing a survival rate of 5.29% for S. aureus and 7.06% for E. coli after near infrared light irradiation. The composite hydrogel further demonstrated efficient bacteria inhibition, enhanced wound healing and collagen deposition in a full-thickness skin defect rat model. Together, the PDA-PAM/Mg²⁺ hydrogel presents an excellent wound dressing with excellent tissue adhesion, wound healing, and antibacterial functions.

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A self-healing multifunctional hydrogel with photothermal antibacterial properties was developed and applied in wound healing.

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The hydrogel exhibited enhanced self-healing and adhesion properties.

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The hydrogel exhibited excellent photothermal effect and photothermal stability and repeatability.

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The hydrogel could accelerate wound healing by promoting cell proliferation and collagen deposition.

Angiogenin Released from ABCB5+ Stromal Precursors Improves Healing of Diabetic Wounds by Promoting Angiogenesis

Severe angiopathy is a major driver for diabetes associated secondary complications. Knowledge on underlying mechanisms essential for advanced therapies to attenuate these pathologies is limited. Injection of ABCB5⁺ stromal precursors (SPs) at the edge of non-healing diabetic wounds in a murine db/db model, closely mirroring human type II diabetes, profoundly accelerates wound closure. Strikingly, enhanced angiogenesis was substantially enforced by the release of the ribonuclease angiogenin from ABCB5⁺ SPs. This compensates for the profoundly reduced angiogenin expression in non-treated murine chronic diabetic wounds. Silencing of angiogenin in ABCB5⁺ SPs prior to injection significantly reduced angiogenesis and delayed wound closure in diabetic db/db mice implying an unprecedented key role for angiogenin in tissue regeneration in diabetes. These data hold significant promise for further refining SPs-based therapies of non-healing diabetic foot ulcers and other pathologies with impaired angiogenesis.

Microplasma Treatment versus Negative Pressure Therapy for Promoting Wound Healing in Diabetic Mice

The delayed healing response of diabetic wounds is a major challenge for treatment. Negative pressure wound therapy (NPWT) has been widely used to treat chronic wounds. However, it usually requires a long treatment time and results in directional growth of wound healing skin tissue. We investigated whether nonthermal microplasma (MP) treatment can promote the healing of skin wounds in diabetic mice. Splint excision wounds were created on diabetic mice, and various wound healing parameters were compared among MP treatment, NPWT, and control groups. Quantitative analysis of the re-epithelialization percentage by detecting Ki67 and DSG1 expression in the extending epidermal tongue (EET) of the wound area and the epidermal proliferation index (EPI) was subsequently performed. Both treatments promoted wound healing by enhancing wound closure kinetics and wound bed blood flow; this was confirmed through histological analysis and optical coherence tomography. Both treatments also increased Ki67 and DSG1 expression in the EET of the wound area and the EPI to enhance re-epithelialization. Increased Smad2/3/4 mRNA expression was observed in the epidermis layer of wounds, particularly after MP treatment. The results suggest that the Smad-dependent transforming growth factor β signaling contributes to the enhancement of re-epithelialization after MP treatment with an appropriate exposure time. Overall, a short-term MP treatment (applied for 30 s twice a day) demonstrated comparable or better efficacy to conventional NPWT (applied for 4 h once a day) in promoting wound healing in diabetic mice. Thus, MP treatment exhibits promise for treating diabetic wounds clinically.

Self-Assembled Nanofibrous Marine Collagen Matrix Accelerates Healing of Full-Thickness Wounds

There is an urgent clinical need for wound dressings to treat skin injuries, particularly full-thickness wounds caused by acute and chronic wounds. Marine collagen has emerged as an attractive and safer alternative due to its biocompatibility, diversity, and sustainability. It has minimum risk of zoonotic diseases and less religious constraints as compared to mammalian collagen. In this study, we reported the development of a self-assembled nanofibrous barramundi (Lates calcarifer) collagen matrix (Nano-BCM), which showed good biocompatibility for full-thickness wound-healing applications. The collagen was extracted and purified from barramundi scales and skin. Thereafter, the physicochemical properties of collagen were systematically evaluated. The process to extract barramundi skin collagen (BC) gave an excellent 45% yield and superior purity (∼100%). More importantly, BC demonstrated structural integrity, native triple helix structure, and good thermal stability. BC demonstrated its efficacy in promoting human primary dermal fibroblast (HDF) and immortalized human keratinocytes (HaCaT) proliferation and migration. Nano-BCM has been prepared via self-assembly of collagen molecules in physiological conditions, which resembled the native extracellular matrix (ECM). The clinical therapeutic efficacy of the Nano-BCM was further evaluated in a full-thickness splinted skin wound mice model. In comparison to a clinically used wound dressing (DuoDerm), the Nano-BCM demonstrated significantly accelerated wound closure and re-epithelization. Moreover, Nano-BCM nanofibrous architecture and its ability to facilitate early inflammatory response significantly promoted angiogenesis and differentiated myofibroblast, leading to enhanced wound healing. Consequently, Nano-BCM demonstrates great potential as an economical and effective nonmammalian substitute to achieve skin regeneration.

Peptide-Conjugated Nano Delivery Systems for Therapy and Diagnosis of Cancer

Peptides are strings of approximately 2-50 amino acids, which have gained huge attention for theranostic applications in cancer research due to their various advantages including better biosafety, customizability, convenient process of synthesis, targeting ability via recognizing biological receptors on cancer cells, and better ability to penetrate cell membranes. The conjugation of peptides to the various nano delivery systems (NDS) has been found to provide an added benefit toward targeted delivery for cancer therapy. Moreover, the simultaneous delivery of peptide-conjugated NDS and nano probes has shown potential for the diagnosis of the malignant progression of cancer. In this review, various barriers hindering the targeting capacity of NDS are addressed, and various approaches for conjugating peptides and NDS have been discussed. Moreover, major peptide-based functionalized NDS targeting cancer-specific receptors have been considered, including the conjugation of peptides with extracellular vesicles, which are biological nanovesicles with promising ability for therapy and the diagnosis of cancer.

Limited Treatment Options for Diabetic Wounds: Barriers to Clinical Translation Despite Therapeutic Success in Murine Models

Significance: Millions of people worldwide suffer from diabetes mellitus and its complications, including chronic diabetic wounds. To date, there are few widely successful clinical therapies specific to diabetic wounds beyond general wound care, despite the vast number of scientific discoveries in the pathogenesis of defective healing in diabetes. Recent Advances: In recent years, murine animal models of diabetes have enabled the investigation of many possible therapeutics for diabetic wound care. These include specific cell types, growth factors, cytokines, peptides, small molecules, plant extracts, microRNAs, extracellular vesicles, novel wound dressings, mechanical interventions, bioengineered materials, and more. Critical Issues: Despite many research discoveries, few have been translated from their success in murine models to clinical use in humans. This massive gap between bench discovery and bedside application begs the simple and critical question: what is still missing? The complexity and multiplicity of the diabetic wound makes it an immensely challenging therapeutic target, and this lopsided progress highlights the need for new methods to overcome the bench-to-bedside barrier. How can laboratory discoveries in animal models be effectively translated to novel clinical therapies for human patients? Future Directions: As research continues to decipher deficient healing in diabetes, new approaches and considerations are required to ensure that these discoveries can become translational, clinically usable therapies. Clinical progress requires the development of new, more accurate models of the human disease state, multifaceted investigations that address multiple critical components in wound repair, and more innovative research strategies that harness both the existing knowledge and the potential of new advances across disciplines.