Rat Full-thickness Skin Wound Research Articles

Self-assembled ROS-triggered Bletilla striata polysaccharide-releasing hydrogel dressing for inflammation-regulation and enhanced tissue-healing

The antimicrobial and pro-healing properties remain critical clinical objectives for skin wound management. However, the escalating problem of antibiotic overuse and the corresponding rise in bacterial resistance necessitates an urgent shift towards an antibiotic-free approach to antibacterial treatment. The quest for antimicrobial efficacy while accelerating wound healing without antibiotic treatment have emerged as innovative strategies in skin wound treatment. Here, a dual-function hydrogel with antimicrobial and enhanced tissue-healing properties was developed by utilizing cyclodextrin, ferrocene, polyethyleneimine (PEI), and Bletilla striata polysaccharide (BSP), through multiple non-covalent interactions, which can intelligently release BSP by recognizing the wound inflammatory microenvironment through the cyclodextrin-ferrocene unit. Moreover, the porosity (65 % - 85 %), Young's modulus (400 KPa - 140 KPa), and DPPH scavenge rate (18 % - 40 %) of the hydrogel are modulated by varying the BSP content. The hydrogel exhibits outstanding antibacterial properties (98.3 % reduction of Escherichia coli observed after exposure to HTFC@BSP-20 for 24 h) and favorable biocompatibility. Furthermore, in a rat full-thickness skin wound model, the dual-function hydrogel significantly accelerates wound healing, increased CD31 expression promotes vascular regeneration, reduced TNF-α express and inhibited the inflammation. This multifunctional ROS responsive hydrogel provides a new perspective for antibiotics-free treatment of skin injuries.

Copper doped carbon dots modified bacterial cellulose with enhanced antibacterial and immune regulatory functions for accelerating wound healing

The microenvironment of wound healing is susceptible to bacterial infection, chronic inflammation, oxidative stress, and inadequate angiogenesis, requiring the development of innovative wound dressings with antibacterial, anti-inflammatory, antioxidant, and angiogenic capabilities. This research crafted a new multifunctional bacterial cellulose composite membrane infused with copper-doped carbon dots (BC/Cu(II)-RCDs). Findings validated the successful loading of copper-doped carbon dots onto the BC membrane via hydrogen bonding interactions. Compared to the pure BC membrane, the BC/Cu(II)-RCDs composite membrane exhibited significantly enhanced hydrophilicity, tensile properties, and thermal stability. Diverse in vitro assays demonstrated excellent biocompatibility and antibacterial activity of BC/Cu(II)-RCDs composite membranes, alongside their ability to expedite the inflammatory phase and stimulate angiogenesis. In vivo trials corroborated the membrane's ability to foster epithelial regeneration, collagen deposition, and tissue regrowth in full-thickness skin wounds in rats while also curbing inflammation in infected full-thickness skin wounds. More importantly, the treatment of the BC/Cu(II)-RCDs composite membrane may result in the activation of VEGF and MAPK signaling proteins, which are key players in cell migration, angiogenesis, and skin tissue development. In essence, the developed BC/Cu(II)-RCDs composite membrane shows promise for treating infected wounds and serves as a viable alternative material for medicinal bandages.

Light-controlled crosslinked multifunctional "Band-Aids" as dual-stage wound dressing for dynamic wound closure

The objective of regenerative wound healing dressings is to accelerate skin tissue regeneration and restore normal physiological function at wound sites. Achieving this goal requires biomaterials capable of repairing distinct phases of wound healing in a way that balances material function, degradation, safety, and tissue growth. In this study, we introduced a novel dual-stage wound dressing system comprising methacrylic anhydride-modified recombinant humanized type III collagen (rhCol III-MA) and methacrylic anhydride-modified dopamine (DMA) (RMDM), which was synthesized through free radical polymerization and π-π stacking. Within this system, RMDM was formulated into two forms with identical compositions: hydrogel and sponge, tailored for application across various stages of wound repair. These materials displayed favorable hemocompatibility, biocompatibility, antioxidant properties, and angiogenic potential in vitro. Moreover, the in vivo experiments also demonstrated that sponges could rapidly stop the bleeding of wounds in mouse tail amputation and liver incision models. Notably, the sponge/gel (S/G) system accelerated wound healing compared to individual sponge and gel treatments in a rat full-thickness skin wound model, underscoring the synergistic benefits of combining sponge and gel materials for wound repair at different stages. Therefore, this research provides valuable insights into designing advanced biomaterials that can be tailored to specific stages of wound healing, which may have significant potential for biomedical applications.Graphical

Preparation and characterization of chitosan/polyvinyl alcohol antibacterial sponge materials

This study utilized the freeze-drying method to create a chitosan (CS) and polyvinyl alcohol (PVA) sponge. To enhance its antibacterial properties, curcumin and nano silver (Cur@Ag) were added for synergistic antibacterial. After adding curcumin and nano silver, the mechanical properties of the composite sponge dressing (CS-PVA-Cur@Ag) were improved. The porosity of the composite sponge dressing was closed to 80%, which was helpful for drug release, and it had good water absorption and water retention rate. The nano silver diameter was 50–80 nm, which was optimal for killing bacteria. Antibacterial tests used Escherichia coli and Staphylococcus aureus demonstrated that little nano silver was required to eliminate bacteria. Finally, in the rat full-thickness skin wound model, the composite sponge dressing can promote wound healing in a short time. In summary, CS-PVA-Cur@Ag wound dressing could protect from bacterial infection and accelerate wound healing. Thus, it had high potential application value for wound dressing.

All-in-One Self-Powered Microneedle Device for Accelerating Infected Diabetic Wound Repair.

Diabetic wound healing remains a significant clinical challenge due to the complex microenvironment and attenuated endogenous electric field. Herein, a novel all-in-one self-powered microneedle device (termed TZ@mMN-TENG) is developed by combining the multifunctional microneedle carried tannin@ZnO microparticles (TZ@mMN) with the self-powered triboelectric nanogenerator (TENG). In addition to the delivery of tannin and Zn2+, TZ@mMN also effectively conducts electrical stimulation (ES) to infected diabetic wounds. As a self-powered device, the TENG can convert biomechanical motion into exogenous ES to accelerate the infected diabetic wound healing. In vitro experiment demonstrated that TZ@mMN shows excellent conductive, high antioxidant ability, and effective antibacterial properties against both Staphylococcus aureus and Escherichia coli (>99% antibacterial rates). Besides, the TZ@mMN-TENG can effectively promote cell proliferation and migration. In the diabetic rat full-thickness skin wound model infected with Staphylococcus aureus, the TZ@mMN-TENG can eliminate bacteria, accelerate epidermal growth (regenerative epidermis: ≈303.3 ± 19.1µm), enhance collagen deposition, inhibit inflammation (lower TNF-α and IL-6 expression), and promote angiogenesis (higher CD31 and VEGF expression) to accelerate infected wound repair. Overall, the TZ@mMN-TENG provides a promising strategy for clinical application in diabetic wound repair.

The wound healing effect of polycaprolactone-chitosan scaffold coated with a gel containing Zataria multiflora Boiss. volatile oil nanoemulsions

AimsThymus plant is a very useful herbal medicine with various properties such as anti-inflammatory and antibacterial. Therefore, the properties of this plant have made this drug a suitable candidate for wound healing. In this study, hydroxypropyl methylcellulose (HPMC) gel containing Zataria multiflora volatile oil nanoemulsion (neZM) along with polycaprolactone/chitosan (PCL-CS) nanofibrous scaffold was used, and the effect of three experimental groups on the wound healing process was evaluated. The first group, HPMC gel containing neZM, the second group, PCL-CS nanofibers, and the third group, HPMC gel containing neZM and bandaged with PCL-CS nanofibers (PCL-CS/neZM). Wounds bandaged with common sterile gas were considered as control.MethodsThe nanoemulsion was synthesized by a spontaneous method and loaded into a hydroxypropyl methylcellulose (HPMC) gel. The DLS test investigated the size of these nanoemulsions. A PCL-CS nanofibrous scaffold was also synthesized by electrospinning method then SEM and contact angle tests investigated morphology and hydrophilicity/hydrophobicity of its surface. The animal study was performed on full-thickness skin wounds in rats, and the process of tissue regeneration in the experimental and control groups was evaluated by H&E and Masson's trichrome staining.ResultsThe results showed that the nanoemulsion has a size of 225±9 nm and has an acceptable dispersion. The PCL-CS nanofibers synthesized by the electrospinning method also show non-beaded smooth fibers and due to the presence of chitosan with hydrophilic properties, have higher surface hydrophobicity than PCL fibers. The wound healing results show that the PCL-CS/neZM group significantly reduced the wound size compared to the other groups on the 7th, 14th, and 21st days. The histological results also show that the PCL-CS/neZM group could significantly reduce the parameters of edema, inflammation, and vascularity and increase the parameters of fibrosis, re-epithelialization, and collagen deposition compared to other groups on day 21.ConclusionThe results of this study show that the PCL-CS/neZM treatment can effectively improve wound healing.

In vitro and in vivo evaluation of alginate hydrogel-based wound dressing loaded with green chemistry cerium oxide nanoparticles.

Interactive wound dressings have displayed promising outcomes in enhancing the wound healing process. This study focuses on creating a nanocomposite wound dressing with interactive and bioactive properties, showcasing potent antioxidant effects. To achieve this, we developed cerium oxide nanoparticles utilizing curcumin as both the reducing and capping agent. Characterization techniques such as SEM, EDX, DLS, Zetasizer, FTIR, and XRD were utilized to analyze the cerium oxide nanoparticles synthesized through a green approach. The image analysis on the obtained TEM images showed that the curcumin-assisted biosynthesized CeO2NPs have a size of 18.8 ± 4.1nm. The peaks located at 28.1, 32.7, 47.1, 56.0, 58.7, 69.0, and 76.4 correspond to (111), (200), (220), (311), (222), (400), and (331) crystallographic planes. We applied the Debye-Scherrer equation and observed that the approximate crystallite size of the biosynthesized NPs is around 8.2nm based on the most intensive broad Bragg peak at 28.1°. The cerium oxide nanoparticles synthesized were integrated into an alginate hydrogel matrix, and the microstructure, porosity, and swelling behavior of the resulting wound dressing were assessed. The characterization analyses provided insights into the physical and chemical properties of the green-synthesized cerium oxide nanoparticles and the alginate hydrogel-based wound dressing. In vitro studies demonstrated that the wound dressing based on alginate hydrogel exhibited favorable antioxidant properties and displayed hemocompatibility and biocompatibility. Animal studies conducted on a rat full-thickness skin wound model showed that the alginate hydrogel-based wound dressing effectively accelerated the wound healing process. Overall, these findings suggest that the alginate hydrogel-based wound dressing holds promise as a highly effective material for wound healing applications.

Flexible Bioactive Glass Nanofiber-Based Self-Expanding Cryogels with Superelasticity and Bioadhesion Enabling Hemostasis and Wound Healing.

Self-expanding cryogels hold unique prospects for treating uncontrollable hemorrhages. However, development of a mechanically robust, tissue-adhesive, and bioactive self-expanding cryogel enabling effective hemostasis and tissue repair has remained a great challenge. Herein, we report a superelastic cellular-structured bioactive glass nanofibrous cryogel (BGNC) composed of highly flexible BG nanofibers and citric acid-cross-linked poly(vinyl alcohol). These BGNCs exhibit high absorption capacity (3169%), fast self-expanding ability, near zero Poisson's ratio, injectability, high compressive recovery at a strain of 80%, robust fatigue resistance (almost no plastic deformation after 800 cycles at a strain of 60%), and good adhesion with diverse tissues. The BGNCs provide sustained release of Ca, Si, and P ions. Moreover, the BGNCs present better blood clotting and blood cell adhesion ability and superior hemostatic capacity in rabbit liver and femoral artery hemorrhage models as compared with commercial gelatin hemostatic sponges. In addition, BGNCs are able to stop bleeding in rat cardiac puncture injury in about 1 min. Furthermore, the BGNCs are capable of promoting rat full-thickness skin wound healing. The development of self-expanding BGNCs with superelasticity and bioadhesion provides a promising strategy for exploring multifunctional hemostatic and wound repair materials.

The preparation of lactoferrin/magnesium silicate lithium injectable hydrogel and application in promoting wound healing

The development of novel wound dressings with highly effective antibacterial and accelerating wound healing properties has become the focus of current research. In this study, a novel and injectable lactoferrin (LF)/lithium magnesium silicate hydrogel (LMSH) was first synthesized through a simple electrostatic interaction method. The physical and biological properties are systematically characterized. The results show that the synthesized LF/LMSH has good antibacterial properties and biocompatibility. More importantly, it can effectively promote wound healing in the rat full-thickness skin wound model after 14 days post-operation, and the healing rate can reach 99.1 %, which is much higher than that of other groups. Meanwhile, histochemical and immunofluorescent staining confirm that the prepared injectable LF/LMSH has good pro-collagen deposition, pro-angiogenic and anti-inflammatory properties. The healed wounds present a consistently thickened epidermis with more follicular and glandular structures, indicating the great potential of the prepared material for wound management.

In situ cell electrospun using a portable handheld electrospinning apparatus for the repair of wound healing in rats.

Slow or non-healing wounds caused by full-thickness skin wounds of various origins have become a difficult challenge in clinical wound treatment. In particular, large full-thickness skin wounds often lead to serious chronic skin wounds that do not heal. Electrospinning technology and stem cell treatment for wound repair have attracted much attention due to its unique advantages. In the current study， we electrospun polyvinyl alcohol (PVA) and bone marrow-derived stem cells (BMSCs) by a handheld electrospinning device, the distribution and interaction of cells and fibres were determined by light and electron microscopy and the cell viability and proliferation were determined by live/dead cell staining. The tissues were analysed by histology with Haematoxylin and Eosin (H&E) and Masson staining and immunohistochemical staining. We found that the fibres were distributed uniformly and BMSCs were distributed between the fibres. Cytotoxicity and cell proliferation tests proved its good biocompatibility. Histological staining shows it can accelerate wound healing and appendages regeneration by promoting granulation tissue repair. The instant PVA/stem cell fibres prepared by a handheld electrospinning device strongly promote the repair of full-thickness skin wounds in rats. The proposed electrospinning technology is expected to have great potential in household, outdoor and battlefield first aid.

Controlled pVEGF delivery via a gene-activated matrix comprised of a peptide-modified non-viral vector and a nanofibrous scaffold for skin wound healing

Regulating cell function and tissue formation by combining gene delivery with functional scaffolds to create gene-activated matrices (GAMs) is a promising strategy for tissue engineering. However, fabrication of GAMs with low cytotoxicity, high transfection efficiency, and long-term gene delivery properties remains a challenge. In this study, a non-viral DNA delivery nanocomplex was developed by modifying poly (D, L-lactic-co-glycolic acid)/polyethylenimine (PLGA/PEI) nanoparticles with the cell-penetrating peptide KALA. Subsequently, the nanocomplex carrying plasmid DNA encoding vascular endothelial growth factor (pVEGF) was immobilized onto a polydopamine-coated electrospun alginate nanofibrous scaffold, resulting in a GAM for enhanced skin wound healing. The nanocomplex exhibited much lower cytotoxicity and comparable or even higher transfection efficiency compared with PEI. The GAM enabled sustained gene release and long-tern transgene expression of VEGF in vitro. In an excisional full-thickness skin wound rat model, the GAM could accelerate wound closure, promote complete re-epithelization, reduce inflammatory response, and enhance neovascularization, ultimately enhancing skin wound healing. The current GAM comprising a low-toxic gene delivery nanocomplex and a biocompatible 3D nanofibrous scaffold demonstrates great potential for mediating long-term cell functions and may become a powerful tool for gene delivery in tissue engineering. Statement of significanceGene delivery is a promising strategy in promoting tissue regeneration as an effective alternative to growth factor delivery, but the study on three-dimensional gene-activated scaffolds remains in its infancy. Herein, a biodegradable nanofibrous gene-activated matrix integrating non-viral nanoparticle vector was designed and evaluated both in vitro and in vivo. The results show that the nanoparticle vector provided high transfection efficiency with minimal cytotoxicity. After surface immobilization of the nanocomplexes carrying plasmid DNA encoding vascular endothelial growth factor (pVEGF), the nanofibrous scaffold enabled sustained DNA release and long-term transgene expression in vitro. In a rat full-thickness skin wound model, the scaffold could accelerate wound healing. This innovative gene-activated matrix can be a promising candidate for tissue regeneration.

A Comparative Analysis of the Structure and Biological Properties of Films and Microfibrous Scaffolds Based on Silk Fibroin.

A comparative analysis of the structure and biological properties of silk fibroin constructions was performed. Three groups of constructions were obtained: films obtained by casting an aqueous solution of silk fibroin and electrospun microfibrous scaffolds based on silk fibroin, with the addition of 30% gelatin per total protein weight. The internal structures of the films and single fibers of the microfibrous scaffolds consisted of densely packed globule structures; the surface area to volume ratios and volume porosities of the microfibrous scaffolds were calculated. All constructions were non-toxic for cells and provide high levels of adhesion and proliferation. The high regenerative potential of the constructions was demonstrated in a rat full-thickness skin wound healing model. The constructions accelerated healing by an average of 15 days and can be considered to be promising constructions for various tasks of tissue engineering and regenerative medicine.

Novel hybrid scaffold for improving the wound repair process: evaluation of combined chitosan/eggshell/vitamin D scaffold for wound healing

The current design requirement of cutaneous wound healing is an ideal wound dressing via biodegradable property through which fibroblasts can support, migrate and proliferate. This study aimed to evaluate the effect of the synthesized hybrid scaffold based on chitosan polymer and a natural source of calcium (Ca) and vitamin D on wound healing. To achieve this purpose, three scaffolds include in chitosan (CS), eggshell + chitosan (ES/CS) and chitosan + eggshell + vitamin D (CS/ES/Vit D) were fabricated using the freeze-drying approach. Synthesized scaffolds were characterized by field emission scanning electron microscopy (FESEM), Fourier transformed infrared (FTIR), X-ray diffraction (XRD) and MTT assay. Histological examinations of the wound healing were performed using hematoxylin–eosin (H&E) and Masson's trichrome staining methods on different days in the rat full-thickness skin wound model. Finally, the effect of the synthesized scaffold was evaluated on the TGF-β1 gene expression. The results of the scaffold characterization showed that scaffolds have the homogeneity structure. The MTT assay indicated that the cultured fibroblasts on the ES/CS and Vit D/ES/CS scaffold had viability higher than those cultured on CS. Also, histological studies demonstrated an increased effect on epithelialization and collagen production and accelerated wound healing using designed scaffolds. The TGF-β1 gene expression in all scaffolds was not significantly different between test groups and controls. In general, it can be concluded that the synthesized scaffolds have the potential to accelerate wound healing and can be used as a suitable scaffold in wound management and skin regeneration.

Green fabrication of seedbed-like Flammulina velutipes polysaccharides–derived scaffolds accelerating full-thickness skin wound healing accompanied by hair follicle regeneration

A novel seedbed-like scaffold was firstly fabricated by the “frozen sectioning” processing method using Flammulina velutipes as a raw material. The Flammulina velutipes polysaccharides scaffold is composed of a natural structure imitating the “ground” (connected and aligned hollow tubes with porous walls). Meanwhile, its biologically active components include polysaccharides and proteins, mimicking the “plant nutrition” in the seedbed. To further optimize the ground and nutrition components, Flammulina velutipes polysaccharides–derived scaffolds (FPDSs) were fabricated via the treatment of original Flammulina velutipes polysaccharides scaffold (labeled FPS) by NaOH, cysteine (labeled as FPS/NaOH, FPS/Cys, respectively). FPDSs were characterized by SEM, FTIR, XRD, water absorption and retention, and mechanical evaluations. From the results, FPS/NaOH and FPS/Cys lost the characteristic big tubes of original strips and had higher water absorption capacities comparing to FPS. Simultaneously, FPS/NaOH had better ductility, FPS/Cys had showed increased stiffness. Biological activities of FPDSs were tested against different types of bacteria exhibiting excellent anti-bacterial activity, and FPS/NaOH and FPS/Cys had dramatically higher anti-bacterial activity than FPS. The cytocompatibility of FPDSs was evaluated utilizing mouse fibroblast cell line (L929), and all FPDSs showed good cytocompatibility. The FPDSs were further applied to a rat full-thickness skin wound model, and they all exhibited obviously accelerated re-epithelialization, among which FPS/NaOH showed the greatest efficiency. FPS/NaOH could shorten the wound-healing process as evidenced by dynamic alterations of the expression levels of specific stagewise markers in the healing areas. Similarly, FPS/NaOH can efficiently induce hair follicle regeneration in the healing skin tissues. In summary, FPDSs exhibit potential functions as seedbeds to promote the regeneration of the “seed” including hair follicles and injured skin, opening a new avenue for wound healing.

PEGylated Platelet-Free Blood Plasma-Based Hydrogels for Full-Thickness Wound Regeneration.

Objective: To develop a cost-effective and clinically usable therapy to treat full-thickness skin injuries. We accomplished this by preparing a viscoelastic hydrogel using polyethylene glycol (PEG)-modified platelet-free plasma (PEGylated PFP) combined with human adipose-derived stem cells (ASCs). Approach: PEGylated PFP hydrogels were prepared by polymerizing the liquid mixture of PEG and PFP±ASCs and gelled either by adding calcium chloride (CaCl2) or thrombin. Rheological and in vitro studies were performed to assess viscoelasticity and the ability of hydrogels to direct ASCs toward a vasculogenic phenotype, respectively. Finally, a pilot study evaluated the efficacy of hydrogels±ASCs using an athymic rat full-thickness skin wound model. Results: Hydrogels prepared within the range of 11 to 27 mM for CaCl2 or 5 to 12.5 U/mL for thrombin exhibited a storage modulus of ∼62 to 87 Pa and ∼47 to 92 Pa, respectively. The PEGylated PFP hydrogels directed ASCs to form network-like structures resembling vasculature, with a fourfold increase in perivascular specific genes that were confirmed by immunofluorescent staining. Hydrogels combined with ASCs exhibited an increase in blood vessel density when applied to excisional rat wounds compared with those treated with hydrogels (110.3 vs. 95.6 BV/mm2; p < 0.05). Furthermore, ASCs were identified in the perivascular region associated with newly forming blood vessels. Innovation: This study demonstrates that PFP modified with PEG along with ASCs can be used to prepare cost-effective stable hydrogels, at the bed-side, to treat extensive skin wounds. Conclusion: These results indicate that PEGylated plasma-based hydrogels combined with ASCs may be a potential regenerative therapy for full-thickness skin wounds.

Exosomes derived from clinical-grade oral mucosal epithelial cell sheets promote wound healing

ABSTRACTThe oral mucosa exhibits unique regenerative properties, sometimes referred to as foetal-like wound healing. Researchers from our institute have used sheets of oral mucosa epithelial cells (OMECs) for regenerative medicine applications including cornea replacement and oesophageal epithelial regeneration for stricture prevention. Here, we have isolated exosomes from clinical-grade production of OMEC sheets from healthy human donors (n = 8), aiming to evaluate the clinical potential of the exosomes to stimulate epithelial regeneration and to improve understanding of the mode-of-action of the cells. Exosomes were isolated from conditioned (cExo) and non-conditioned (ncExo) media. Characterization was performed using Western blot for common exosomal-markers: CD9 and flotillin were positive while annexin V, EpCam and contaminating marker GRP94 were negative. Nanoparticle tracking analysis revealed a diameter of ~120 nm and transmission electron microscopy showed a corresponding size and spherical appearance. Human skin fibroblasts exposed to exosomes showed dose-dependent reduction of proliferation and a considerable increase of growth factor gene expression (HGF, VEGFA, FGF2 and CTGF). The results were similar for both groups, but with a trend towards a larger effect from cExo. To study adhesion, fluorescently labelled exosomes were topically applied to pig oesophageal wound-beds ex vivo and subsequently washed. Positive signal could be detected after as little as 1 min of adhesion, but increased adhesion time produced a stronger signal. Next, labelled exosomes were added to full-thickness skin wounds in rats and signal was detected up to 5 days after application. cExo significantly reduced the wound size at days 6 and 17. In conclusion, exosomes from OMEC sheets showed pro-regenerative effects on skin wound healing. This is the first time that the healing capacity of the oral mucosa is studied from an exosome perspective. These findings might lead to a combinational therapy of cell sheets and exosomes for future patients with early oesophageal cancer.

The effect of Korean Red Ginseng on full-thickness skin wound healing in rats

BackgroundPanax ginseng is regarded as one of the best compounds for promoting health, and it has been used traditionally as a medicinal herb. Recently, Korean Red Ginseng (RG) has been shown to protect skin from aging and wrinkling; it can also relieve atopic dermatitis and allergy symptoms. This study aimed to evaluate RG's effects on the regeneration of the full-thickness skin wounds in rat. MethodsFull-thickness skin wounds were generated in rats, and then RG was administered either orally or topically. The wound-healing effects of RG were investigated by assessing wound size, mRNA expression patterns of genes related to wound healing, histological staining, and measurements of lipid, moisture, and elasticity in skin tissues. ResultsThe wound size was smaller, and tissue regeneration rate was faster in the RG-treated group than that in the control group on days 15 and 20 after initiating treatment. On postoperative day 20, skin lipid and moisture content had increased significantly in the RG-treated group. Significant increases in the gene expression levels of transforming growth factor-β1 and vascular endothelial growth factor were found in the RG group during the early stages of wound healing. Matrix metalloproteinase-1 and matrix metalloproteinase-9 showed significant increases in gene expression levels on day 20. ConclusionThe results suggested that RG may promote healing of full-thickness skin wounds in rats. They also provided basic insights into the effects of RG on skin regeneration, supporting its use as a dressing material for wound treatment and its development as a functional food.

Moldable Hyaluronan Hydrogel Enabled by Dynamic Metal–Bisphosphonate Coordination Chemistry for Wound Healing

Biomaterial-based regenerative approaches would allow for cost-effective off-the-shelf solution for the treatment of wounds. Hyaluronan (HA)-based hydrogel is one attractive biomaterial candidate because it is involved in natural healing processes, including inflammation, granulation, and reepithelialization. Herein, dynamic metal-ligand coordination bonds are used to fabricate moldable supramolecular HA hydrogels with self-healing properties. To achieve reversible crosslinking of HA chains, the biopolymer is modified with pendant bisphosphonate (BP) ligands using carbodiimide coupling and chemoselective "click" reactions. Hydrogel is formed immediately after simple addition of silver (Ag+ ) ions to the solution of HA containing BP groups (HA-BP). Compared with previous HA-based wound healing hydrogels, the HA-BP·Ag+ hydrogel is highly suitable for clinical use as it can fill irregularly shaped wound defects without the need for premolding. The HA-BP·Ag+ hydrogel shows antimicrobial properties to both Gram-positive and Gram-negative bacterial strains, enabling prevention of infections in wound care. In vivo evaluation using a rat full-thickness skin wound model shows significantly lower wound remaining rate and a thicker layer of regenerated epidermis as compared with the group left without treatment. The presented moldable and self-healing supramolecular HA hydrogel with "ready-to-use" properties possesses a great potential for regenerative wound treatment.

Pre-vascularization Enhances Therapeutic Effects of Human Mesenchymal Stem Cell Sheets in Full Thickness Skin Wound Repair.

Split thickness skin graft (STSG) implantation is one of the standard therapies for full thickness wound repair when full thickness autologous skin grafts (FTG) or skin flap transplants are inapplicable. Combined transplantation of STSG with dermal substitute could enhance its therapeutic effects but the results remain unsatisfactory due to insufficient blood supply at early stages, which causes graft necrosis and fibrosis. Human mesenchymal stem cell (hMSC) sheets are capable of accelerating the wound healing process. We hypothesized that pre-vascularized hMSC sheets would further improve regeneration by providing more versatile angiogenic factors and pre-formed microvessels. In this work, in vitro cultured hMSC cell sheets (HCS) and pre-vascularized hMSC cell sheets (PHCS) were implanted in a rat full thickness skin wound model covered with an autologous STSG. Results demonstrated that the HCS and the PHCS implantations significantly reduced skin contraction and improved cosmetic appearance relative to the STSG control group. The PHCS group experienced the least hemorrhage and necrosis, and lowest inflammatory cell infiltration. It also induced the highest neovascularization in early stages, which established a robust blood micro-circulation to support grafts survival and tissue regeneration. Moreover, the PHCS grafts preserved the largest amount of skin appendages, including hair follicles and sebaceous glands, and developed the smallest epidermal thickness. The superior therapeutic effects seen in PHCS groups were attributed to the elevated presence of growth factors and cytokines in the pre-vascularized cell sheet, which exerted a beneficial paracrine signaling during wound repair. Hence, the strategy of combining STSG with PHCS implantation appears to be a promising approach in regenerative treatment of full thickness skin wounds.

Adipose-derived aldehyde dehydrogenase-expressing cells promote dermal regenerative potential with collagen-glycosaminoglycan scaffold.

Aldehyde dehydrogenase (ALDH) is an enzyme that plays an important role in retinoid metabolism and highly expressed in stem cells. This study isolated ALDH-expressing cells from subcutaneous adipose tissue and investigated their potential to enhance healing in a full-thickness skin wound in rats by co-implanting them with collagen-glycosaminoglycan (c-GAG) scaffolds. ALDH-positive cells were isolated by a fluorescence-activated cell sorting technique from Lewis rat's stromal-vascular-fraction (SVF) and transplanted with c-GAG scaffolds in a rat full-thickness skin wound model. At 7 days after surgery, the microscopic appearance of c-GAG scaffolds seeded with ALDH-positive was compared with those of uncultured-SVF, and cultured-SVF adipose-derived stromal cells (ASCs). The thickness of cellular ingrowth in the ASC group (630 ± 180 μm) was significantly thicker than that in the control (390 ± 120 μm) or SVF (380 ± 140 μm) groups, but non-significantly thicker than that in the ALDH-positive group (570 ± 220 μm). The thickness of regenerated collagen layer was significantly thicker in the ALDH-positive group (160 ± 110 μm) than in the ASCs (81 ± 41 μm), the control (65 ± 24 μm), or SVF (64 ± 34 μm) groups. Immunofluorescent staining with CD31 proved that transplanted ALDH-positive cells differentiated into vascular endothelial cells in c-GAG scaffolds. Combined transplantation with c-GAG scaffolds and adipose-derived ALDH-positive cells promoted dermal regeneration, giving a possibility that ALDH-positive cells would greatly shorten the waiting period before secondary autologous skin grafting was possible.