Extracellular Matrix and Dermal Fibroblast Function in the Healing Wound

Nigella sativa and Its Active Compound, Thymoquinone, Accelerate Wound Healing in an In Vivo Animal Model: A Comprehensive Review

Nigella sativa (NS) has been reported to have a therapeutic effect towards skin wound healing via its anti-inflammatory, tissue growth stimulation, and antioxidative properties. This review examines all the available studies on the association of Nigella sativa (NS) and skin wound healing. The search was performed in Medline via EBSCOhost and Scopus databases to retrieve the related papers released between 1970 and March 2020. The principal inclusion criteria were original article issued in English that stated wound healing criteria of in vivo skin model with topically applied NS. The search discovered 10 related articles that fulfilled the required inclusion criteria. Studies included comprise different types of wounds, namely excisional, burn, and diabetic wounds. Seven studies unravelled positive results associated with NS on skin wound healing. Thymoquinone has anti-inflammatory, antioxidant, and antibacterial properties, which mainly contributed to wound healing process.

A Systematic Review on Classification, Identification, and Healing Process of Burn Wound Healing

Because of the intrinsic complexity, the classification of wounds is important for the diagnosis, management, and choosing the correct treatment based on wound type. Generally, burn injuries are classified as a class of wounds in which injury is caused by heat, cold, electricity, chemicals, friction, or radiation. On the other hand, wound healing is a complex process, and understanding the biological trend of this process and differences in the healing process of different wounds could reduce the possible risk in many cases and greatly reduce the future damage to the injured tissue and other organs. The aim of this review is to provide a general perspective for the burn wound location among the other types of injuries and summarizing as well as highlighting the differences of these types of wounds with emphasizing on factors affecting thereof.

Effect of photobiomodulation on cellular migration and survival in diabetic and hypoxic diabetic wounded fibroblast cells

A disrupted wound repair process often leads to the development of chronic wounds, and pose a major physical, social and economic inconvenience on patients and the public health sector. Chronic wounds are a common complication seen in diabetes mellitus (DM), and often the severity necessitates amputation of the lower limbs. Recently, there has been increasing evidence that photobiomodulation (PBM) initiates wound healing, including increased protein transcription for cell proliferation, viability, migration and tissue reepithelialisation. Here, the hypothesis that PBM at a wavelength of 660 nm and energy density of 5 J/cm² regulates wound repair in diabetic wounded and hypoxic diabetic wounded fibroblasts by enhancing cell migration and survival was investigated. PBM increased migration and survival in diabetic wounded and hypoxic diabetic wounded fibroblasts. Our findings suggest that PBM enhances migration and survival in diabetic wounded and hypoxic diabetic wounded fibroblasts, indicating that this therapeutic method may be beneficial against chronic wounds in diabetic patients.

A Review of the Contribution of Mast Cells in Wound Healing: Involved Molecular and Cellular Mechanisms

Mast cells (MCs), apart from their classic role in allergy, contribute to a number of biologic processes including wound healing. In particular, two aspects of their histologic distribution within the skin have attracted the attention of researchers to study their wound healing role; they represent up to 8% of the total number of cells within the dermis and their cutaneous versions are localized adjacent to the epidermis and the subdermal vasculature and nerves. At the onset of a cutaneous injury, the accumulation of MCs and release of proinflammatory and immunomodulatory mediators have been well documented. The role of MC-derived mediators has been investigated through the stages of wound healing including inflammation, proliferation, and remodeling. They contribute to hemostasis and clot formation by enhancing the expression of factor XIIIa in dermal dendrocytes through release of TNF-α, and contribute to clot stabilization. Keratinocytes, by secreting stem cell factor (SCF), recruit MCs to the site. MCs in return release inflammatory mediators, including predominantly histamine, VEGF, interleukin (IL)-6, and IL-8, that contribute to increase of endothelial permeability and vasodilation, and facilitate migration of inflammatory cells, mainly monocytes and neutrophils to the site of injury. MCs are capable of activating the fibroblasts and keratinocytes, the predominant cells involved in wound healing. MCs stimulate fibroblast proliferation during the proliferative phase via IL-4, vascular endothelial growth factor (VEGF), and basic fibroblast growth factor (bFGF) to produce a new extracellular matrix (ECM). MC-derived mediators including fibroblast growth factor-2, VEGF, platelet-derived growth factor (PDGF), TGF-β, nerve growth factor (NGF), IL-4, and IL-8 contribute to neoangiogenesis, fibrinogenesis, or reepithelialization during the repair process. MC activation inhibition and targeting the MC-derived mediators are potential therapeutic strategies to improve wound healing through reduced inflammatory responses and scar formation.

Porcine mesothelium matrix as a biomaterial for wound healing applications

The increasing economic burden of wound healing in healthcare systems requires the development of functional therapies. Xenografts with preserved extracellular matrix (ECM) structure and biofunctional components overcome major limitations of autografts and allografts (e.g. availability) and artificial biomaterials (e.g. foreign body response). Although porcine mesothelium is extensively used in clinical practice, it is under-investigated for wound healing applications. Herein, we compared the biochemical and biological properties of the only two commercially available porcine mesothelium grafts (Meso Biomatrix® and Puracol® Ultra ECM) to traditionally used wound healing grafts (Endoform™, ovine forestomach and MatriStem®, porcine urinary bladder) and biomaterials (Promogran™, collagen/oxidized regenerated cellulose). The Endoform™ and the Puracol® Ultra ECM showed the highest (p<0.05) soluble collagen and elastin content. The MatriStem® had the highest (p<0.05) basic fibroblast growth factor (FGFb) content, whereas the Meso Biomatrix® had the highest (p<0.05) transforming growth factor beta-1 (TGF-β1) and vascular endothelial growth factor (VEGF) content. All materials showed tissue-specific structure and composition. The Endoform™ and the Meso Biomatrix® had some nuclei residual matter. All tissue grafts showed similar (p>0.05) response to enzymatic degradation, whereas the Promogran™ was not completely degraded by matrix metalloproteinase (MMP)-8 and was completely degraded by elastase. The Promogran™ showed the highest (p<0.05) permeability to bacterial infiltration. The Promogran™ showed by far the lowest dermal fibroblast and THP-1 attachment and growth. All tested materials showed significantly lower (p<0.05) tumor necrosis factor-alpha (TNF-α) expression than the lipopolysaccharides group. The MatriStem® and the Puracol® Ultra ECM promoted the highest (p<0.05) number of micro-vessel formation, whereas the Promogran™ the lowest (p<0.05). Collectively, these data confer that porcine mesothelium has the potential to be used as a wound healing material, considering its composition, resistance to enzymatic degradation, cytocompatibility, and angiogenic potential.

Tunable bioactivity and mechanics of collagen-based tissue engineering constructs: A comparison of EDC-NHS, genipin and TG2 crosslinkers

Due to its ubiquity and versatility in the human body, collagen is an ideal base material for tissue-engineering constructs. Chemical crosslinking treatments allow precise control of the biochemical and mechanical properties through macromolecular modifications to the structure of collagen. In this work, three key facets regarding the collagen crosslinking process are explored. Firstly, a comparison is drawn between the carbodiimide-succinimide (EDC-NHS) system and two emerging crosslinkers utilising alternate chemistries: genipin and tissue transglutaminase (TG2). By characterising the chemical changes upon treatment, the effect of EDC-NHS, genipin and TG2 crosslinking mechanisms on the chemical structure of collagen, and thus the mechanical properties conferred to the substrate is explored. Secondly, the relative importance of mechanical and biochemical cues on cellular phenomena are investigated, including cell viability, integrin-specific attachment, spreading and proliferation. Here, we observe that for human dermal fibroblasts, long-term, stable proliferation is preconditioned by the availability of suitable binding sites, irrespective of the substrate modulus post-crosslinking. Finally, as seen in the graphical abstract we show that by choosing the appropriate crosslinker chemistries, a materials selection map can be drawn for collagen films, encompassing both a range of tensile modulus and fibroblast proliferation which can be modified independently. Thus, in addition to a range of parameters that can be modified in collagen constructs, we demonstrate a route to obtaining tunable bioactivity and mechanics in collagen constructs is uncovered, that is exclusively driven by the crosslinking process.

Cellular retinoic acid binding protein-II expression and its potential role in skin aging

Skin aging is an intricate biological process consisting of intrinsic and extrinsic alterations of epidermal and dermal structures. Retinoids play an important role in epidermal cell growth and differentiation and are beneficial to counteract skin aging. Cellular retinoic acid binding protein-II (CRABP-II) selectively binds all trans-retinoic acid, the most active retinoid metabolite, contributing to regulate intracytoplasmic retinoid trafficking and keratinocyte differentiation. Immunohistochemistry revealed a reduced epidermal and dermal CRABP-II expression in aged human and mouse skin. To better clarify the role of CRABP-II, we investigated age-related skin changes in CRABP-II knock-out mice. We documented an early reduction of keratinocyte layers, proliferation and differentiation rate, dermal and hypodermal thickness, pilosebaceous units and dermal vascularity in CRABP-II knock-out compared with wild-type mice. Ultrastructural investigation documented reduced number and secretion of epidermal lamellar bodies in CRABP-II knock-out compared with wild-type mice. Cultured CRABP-II knock-out-derived dermal fibroblasts proliferated less and showed reduced levels of TGF-β signal-related genes, Col1A1, Col1A2, and increased MMP2 transcripts compared with those from wild-type. Our data strongly support the hypothesis that a reduction of CRABP-II expression accelerates and promotes skin aging, and suggest CRABP-II as a novel target to improve the efficacy of retinoid-mediated anti-aging therapies.

Bioactive ECM Mimic Hyaluronic Acid Dressing via Sustained Releasing of bFGF for Enhancing Skin Wound Healing

Successful dermal wound regeneration requires the coordination of repair cells and cellular signals with the extracellular matrix (ECM), which serves as an indispensable mechanical and biological supporter for cell functions and communications with varied cytokines during healing processes. Here, we developed an injectable bioactive wound dressing, methacrylated hyaluronic acid (Me-HA)-based hydrogel loading with basic fibroblast growth factor (bFGF), endowing the dressing with the pleiotropic bioactivity to mimic natural ECM. This bFGF@Me-HA dressing was applied to a mouse with full-thickness excisional wounds to investigate its positive roles in wound repair owing to the complementary functions of HA with sustained release of bioactive bFGF. Compared with the single Me-HA and bFGF group, bFGF@Me-HA hydrogel dressings significantly enhanced wound healing with accelerated re-epithelialization, granulation formation, collagen, deposition and skin appendage regeneration. Further investigations showed significantly promoted cell proliferation and vascularization in the bFGF@Me-HA group, which was mediated by the upregulation of transforming growth factor-β (TGF-β) and vascular endothelial growth factor (VEGF) expressions. In conclusion, this bFGF@Me-HA hydrogel realized the optimization of simple ECM mimic dressing via introducing the bioactive effector, bFGF, and has the potential to be widely used as an effective bioactive ECM-based wound dressing in future wound care.

Graphene-based 2D constructs for enhanced fibroblast support

Complex skin wounds have always been a significant health and economic problem worldwide due to their elusive and sometimes poor or non-healing conditions. If not well-treated, such wounds may lead to amputation, infections, cancer, or even death. Thus, there is a need to efficiently generate multifunctional skin grafts that address a wide range of skin conditions, including non-healing wounds, and enable the regeneration of new skin tissue. Here, we propose studying pristine graphene and two of its oxygen-functionalized derivatives-high and low-oxygen graphene films-as potential substrates for skin cell proliferation and differentiation. Using BJ cells (human foreskin-derived fibroblasts) to represent basic skin cells, we show that the changes in surface properties of pristine graphene due to oxygen functionalization do not seem to statistically impact the normal proliferation and maturation of skin cells. Our results indicate that the pristine and oxidized graphenes presented relatively low cytotoxicity to BJ fibroblasts and, in fact, support their growth and bioactivity. Therefore, these graphene films could potentially be integrated into more complex skin regenerative systems to support skin regeneration. Because graphene's surface can be relatively easily functionalized with various chemical groups, this finding presents a major opportunity for the development of various composite materials that can act as active components in regenerative applications such as skin regeneration.

Topology control of human fibroblast cells monolayer by liquid crystal elastomer

Eukaryotic cells in living tissues form dynamic patterns with spatially varying orientational order that affects important physiological processes such as apoptosis and cell migration. The challenge is how to impart a predesigned map of orientational order onto a growing tissue. Here, we demonstrate an approach to produce cell monolayers of human dermal fibroblasts with predesigned orientational patterns and topological defects using a photoaligned liquid crystal elastomer (LCE) that swells anisotropically in an aqueous medium. The patterns inscribed into the LCE are replicated by the tissue monolayer and cause a strong spatial variation of cells phenotype, their surface density, and number density fluctuations. Unbinding dynamics of defect pairs intrinsic to active matter is suppressed by anisotropic surface anchoring allowing the estimation of the elastic characteristics of the tissues. The demonstrated patterned LCE approach has potential to control the collective behavior of cells in living tissues, cell differentiation, and tissue morphogenesis.

Spirulina protein promotes skin wound repair in a mouse model of full-thickness dermal excisional wound

The skin protects body from environmental damage. Skin wounds lead to microbial infection and harmful agent injury. Thus, wound repair is crucial for the recovery of the normal function of skin tissue. The present study investigated the promoting effects of spirulina protein (SPCP) in mice on skin wound repair and also aimed to elucidate the potential underlying mechanisms. The results revealed that SPCP promoted the skin wound repair in a mouse model of full-thickness excisional wounds. SPCP induced an increase in the expression level of α-smooth muscle actin (α-SMA). The activities of superoxide dismutase (SOD) and catalase (CAT) were enhanced by SPCP treatment in the granulation tissue. In addition, SPCP decreased the level of malondialdehyde (MDA) in the granulation tissue. Western blot analysis revealed that SPCP enhanced the phosphorylation and activation of protein kinase B (Akt) and extracellular signal-regulated kinase (ERK). Moreover, the expression level of transforming growth factor β1 (TGF-β1) was increased in the SPCP-treated groups. The phosphorylation level of Smad2 was also increased by treatment of SPCP. Furthermore, SPCP promoted the expression of collagen in the granulation tissue. Taken together, these findings indicate that SPCP exerts a promoting effect on skin wound repair. The Akt, ERK and TGF-β1 signaling pathways are involved in this process.

The role of extracellular matrix in the pathophysiology of diabetic wounds

Impaired healing leading to the formation of ulcerated wounds is a critical concern in patients with diabetes. Abnormalities in extracellular matrix (ECM) production and remodeling contribute to tissue dysfunction and delayed healing. Specifically, diabetes-induced changes in the expression and/or activity of structural proteins, ECM-modifying enzymes, proteoglycans, and matricellular proteins have been reported. In this review, we provide a summary of the key ECM molecules and associated changes in skin and diabetic wounds. Such information should allow for new insights in the understanding of impaired wound healing and lead to the development of ECM-based therapeutic strategies.

Cell-specific expression of the transcriptional regulator RHAMM provides a timing mechanism that controls appropriate wound re-epithelialization

Prevention of aberrant cutaneous wound repair and appropriate regeneration of an intact and functional integument require the coordinated timing of fibroblast and keratinocyte migration. Here, we identified a mechanism whereby opposing cell-specific motogenic functions of a multifunctional intracellular and extracellular protein, the receptor for hyaluronan-mediated motility (RHAMM), coordinates fibroblast and keratinocyte migration speed and ensures appropriate timing of excisional wound closure. We found that, unlike in WT mice, in Rhamm-null mice, keratinocyte migration initiates prematurely in the excisional wounds, resulting in wounds that have re-surfaced before the formation of normal granulation tissue, leading to a defective epidermal architecture. We also noted aberrant keratinocyte and fibroblast migration in the Rhamm-null mice, indicating that RHAMM suppresses keratinocyte motility but increases fibroblast motility. This cell context-dependent effect resulted from cell-specific regulation of extracellular signal-regulated kinase 1/2 (ERK1/2) activation and expression of a RHAMM target gene encoding matrix metalloprotease 9 (MMP-9). In fibroblasts, RHAMM promoted ERK1/2 activation and MMP-9 expression, whereas in keratinocytes, RHAMM suppressed these activities. In keratinocytes, loss of RHAMM function or expression promoted epidermal growth factor receptor-regulated MMP-9 expression via ERK1/2, which resulted in cleavage of the ectodomain of the RHAMM partner protein CD44 and thereby increased keratinocyte motility. These results identify RHAMM as a key factor that integrates the timing of wound repair by controlling cell migration.

Impact of intercellular crosstalk between epidermal keratinocytes and dermal fibroblasts on skin homeostasis

Dermal fibroblasts seem critical for epidermal maturation and differentiation and recent work demonstrated that diseased fibroblasts may drive pathophysiological processes. Nevertheless, still very little is known about the actual crosstalk between epidermal keratinocytes and dermal fibroblasts and the impact of dermal fibroblasts on epidermal maturation and differentiation. Aiming for a more fundamental understanding of the impact of the cellular crosstalk between keratinocytes and fibroblasts on the skin homeostasis, we generated full-thickness skin equivalents with and without fibroblasts and subsequently analysed them for the expression of skin differentiation markers, their barrier function, skin lipid content and epidermal cell signalling. Skin equivalents without fibroblasts consistently showed an impaired differentiation and dysregulated expression of skin barrier and tight junction proteins, increased skin permeability, and a decreased skin lipid/protein ratio. Most interestingly, impaired Ras/Raf/ERK/MEK signalling was evident in skin equivalents without fibroblasts. Our data clearly indicate that the epidermal-dermal crosstalk between keratinocytes and fibroblasts is critical for adequate skin differentiation and that fibroblasts orchestrate epidermal differentiation processes.

Photo-responsive supramolecular hyaluronic acid hydrogels for accelerated wound healing

Supramolecular hydrogels confer control over structural properties in a reversible, dynamic, and biomimetic fashion. The design of supramolecular hydrogels with an improved structural and functional recapitulation of damaged organs is important for clinical applications. For wound healing management, in particular, an effective healing process, through the modulation of epidermal growth factor (EGF) delivery using supramolecular polysaccharide hydrogels, has yet to be developed. In this study, photo-responsive supramolecular polysaccharide hydrogels were formed through host-guest interactions between azobenzene and β-cyclodextrin groups conjugated to hyaluronic acid chains. By exploiting the photoisomerization properties of azobenzene under different wavelengths, a supramolecular hydrogel featuring a dynamic spatial network crosslink density through the application of a light stimulus was obtained. Under ultra violet (UV) light, the loosened hydrogel can rapidly release EGF, thereby enhancing EGF delivery at the wound site. Based on an in vivo assessment of the healing process through a full-thickness skin defect model, the controlled EGF release from a supramolecular hydrogel exhibited superior wound healing efficiency with respect to granulation tissue formation, growth factor levels, and angiogenesis. Therefore, the proposed supramolecular hydrogels are potentially valuable as controlled delivery systems for future clinical wound healing applications.

Fibroblast Proliferation and Migration in Wound Healing by Phytochemicals: Evidence for a Novel Synergic Outcome

Wound-healing is a dynamic skin reparative process that results in a sequence of events, including inflammation, proliferation, and migration of different cell types as fibroblasts. Fibroblasts play a crucial role in repairing processes, from the late inflammatory phase until the fully final epithelization of the injured tissue. Within this context, identifying tools able to implement cell proliferation and migration could improve tissue regeneration. Recently, plants species from all over the world are coming out as novel tools for therapeutic applications thanks to their phytochemicals, which have antioxidant properties and can promote wound healing. In this paper, we aimed at investigating antioxidant activity of waste extracts from different medicinal plants, endemic of the Mediterranean area, on fibroblast proliferation and wound healing. We determined the amount of total phenols and anti-oxidant activity by ABTS assay. We then evaluated the cytotoxicity of the compounds and the proliferative capabilities of fibroblasts by scratch assay. Our results showed that waste extracts retain antioxidant and regenerative properties, inducing tissue re-establishment after environmental stress exposure. Taken together, our findings suggest that waste material could be used in the future also in combinations to stimulate wound healing processes and antioxidant responses in damaged skin.

Human Adventitial Fibroblast Phenotype Depends on the Progression of Changes in Substrate Stiffness

Adventitial fibroblasts (AFs) are major contributors to vascular remodeling and maladaptive cascades associated with arterial disease, where AFs both contribute to and respond to alterations in their surrounding matrix. The relationships between matrix modulus and human aortic AF (AoAF) function are investigated using poly(ethylene glycol)-based hydrogels designed with matrix metalloproteinase (MMP)-sensitive and integrin-binding peptides. Initial equilibrium shear storage moduli for the substrates examined are 0.33, 1.42, and 2.90 kPa; after 42 days of culture, all hydrogels exhibit similar storage moduli (0.3-0.7 kPa) regardless of initial modulus, with encapsulated AoAFs spreading and proliferating. In 10 and 7.5 wt% hydrogels, modulus decreases monotonically throughout culture; however, in 5 wt% hydrogels, modulus increases after an initial 7 days of culture, accompanied by an increase in myofibroblast transdifferentiation and expression of collagen I and III through day 28. Thereafter, significant reductions in both collagens occur, with increased MMP-9 and decreased tissue inhibitor of metalloproteinase-1/-2 production. Releasing cytoskeletal tension or inhibiting cellular protein secretion in 5 wt% hydrogels block the stiffening of the polymer matrix. Results indicate that encapsulated AoAFs initiate cell-mediated matrix remodeling and demonstrate the utility of dynamic 3D systems to elucidate the complex interactions between cell behavior and substrate properties.

Design and biofabrication of dermal regeneration scaffolds: role of oligomeric collagen fibril density and architecture

Aim: To evaluate dermal regeneration scaffolds custom-fabricated from fibril-forming oligomeric collagen where the total content and spatial gradient of collagen fibrils was specified. Materials & methods: Microstructural and mechanical features were verified by electron microscopy and tensile testing. The ability of dermal scaffolds to induce regeneration of rat full-thickness skin wounds was determined and compared with no fill control, autograft skin and a commercial collagen dressing. Results: Increasing fibril content of oligomer scaffolds inhibited wound contraction and decreased myofibroblast marker expression. Cellular and vascular infiltration of scaffolds over the 14-day period varied with the graded density and orientation of fibrils. Conclusion: Fibril content, spatial gradient and orientation are important collagen scaffold design considerations for promoting vascularization and dermal regeneration while reducing wound contraction.

Enzyme inhibitory assessment of the isolated constituents from Plantago holosteum Scop

Plants of the Plantago genus are widely used in Turkish folk medicine especially for the treatment of wound, abscess, and inflammation. The aqueous extract and five phenylethanoid glycosides acteoside (1), arenarioside (2), echinacoside (3), isoacteoside (4), and leucosceptoside A (5) isolated from the aerial parts and roots of Plantago holosteum Scop. (Plantaginaceae) were tested for their possible inhibitory activity against hyaluronidase, elastase, and collagenase, related to wound pathogenesis. Even though the aqueous extract prepared from the aerial parts (36.26%) and roots (47.01%) and the isolated compounds acteoside (29.13%), echinacoside (28.73%), and isoacteoside (31.69%) exerted a notable inhibition, arenarioside and leucosceptoside A were found inactive in the hyaluronidase enzyme inhibition test. Similar results were obtained from the collagenase enzyme inhibition test. The aqueous extract prepared from the aerial parts (31.09%) and roots (35.17%), echinacoside (25.13%), and isoacteoside (23.85%) exerted a notable inhibition in this test. However, none of the extracts and isolated compounds displayed elastase enzyme inhibitory activity. The experimental data demonstrated that P. holosteum displayed a remarkable enzyme inhibitory activity against hyaluronidase and collagenase. This paper is the first report regarding the in vitro enzyme inhibitory activity of P. holosteum.

Pexiganan in Combination with Nisin to Control Polymicrobial Diabetic Foot Infections

Diabetic foot ulcers (DFUs) are major complications of Diabetes mellitus being responsible for significant morbidity and mortality. DFUs frequently become chronically infected by a complex community of bacteria, including multidrug-resistant and biofilm-producing strains of Staphylococcus aureus and Pseudomonas aeruginosa. Diabetic foot infections (DFI) are often recalcitrant to conventional antibiotics and alternative treatment strategies are urgently needed. Antimicrobial Peptides (AMPs), such as pexiganan and nisin, have been increasingly investigated and reported as effective antimicrobial agents. Here, we evaluated the antibacterial potential of pexiganan and nisin used in combination (dual-AMP) to control the growth of planktonic and biofilm co-cultures of S. aureus and P. aeruginosa clinical strains, co-isolated from a DFU. A DFU collagen three-dimensional (3D) model was used to evaluate the distribution and efficacy of AMPs locally delivered into the model. The concentration of pexiganan required to inhibit and eradicate both planktonic and biofilm-based bacterial cells was substantially reduced when used in combination with nisin. Moreover, incorporation of both AMPs in a guar gum delivery system (dual-AMP biogel) did not affect the dual-AMP antimicrobial activity. Importantly, the application of the dual-AMP biogel resulted in the eradication of the S. aureus strain from the model. In conclusion, data suggest that the local application of the dual-AMPs biogel constitutes a potential complementary therapy for the treatment of infected DFU.

Chondroitin Sulfate Promotes the Proliferation of Keloid Fibroblasts Through Activation of the Integrin and Protein Kinase B Pathways

Keloids are dermal fibroproliferative tumors that arise beyond the boundary of the original wound edges and invades adjacent tissue. Keloids are characterized by the extensive production of extracellular matrix (ECM) and abnormal fibroblast proliferation. Chondroitin sulfate (CS) is one of the major structural components of cartilage and ECM. Recently, we reported the over-accumulation of CS in keloid lesions. Keloid-derived fibroblasts (KFs) and normal dermal fibroblasts (NFs) were incubated with CS. The fibroblast proliferation rate was analyzed using a tetrazolium salt colorimetric assay. The activation of the intracellular signaling pathway was analyzed by Western blotting. Wortmannin, a PI3K inhibitor, and anti-integrin antibodies were tested to investigate the mechanism of the CS-induced cell proliferation. CS strongly stimulated the proliferation of KFs, but not NFs. The analysis of the intracellular signal transduction pathway revealed that the stimulation effect of CS on KF proliferation was due to the activation of the protein kinase B (AKT) pathway and that integrin α1 was responsible for this phenomenon. We revealed that CS probably activates the AKT pathway through integrin to induce KF proliferation. CS may be a novel clinical therapeutic target in keloids.

Evaluation of antifungal effect and toxicity of xanthyletin and two bacterial metabolites against Thai isolates of Pythium insidiosum

Pythiosis is a harmful disease caused by Pythium insidiosum, an aquatic oomycete. Therapeutic protocols based on antifungal drugs are often ineffective because the cytoplasmic membrane of P. insidiosum does not contain ergosterol. Therefore, the treatment of pythiosis is still challenging, particularly making use of natural products and secondary metabolites from bacteria. In this study, xanthyletin and substances obtained from Pseudomonas stutzeri ST1302 and Klebsiella pneumoniae ST2501 exhibited anti-P. insidiosum activity and, moreover, xanthyletin was non-toxic against human cell lines. The hyphae of P. insidiosum treated with these three substances exhibited lysis holes on a rough surface and release of anamorphic material. Therefore, xanthyletin could be considered a promising alternative agent for treating cutaneous pythiosis in the near future.

Single-step, acid-based fabrication of homogeneous gelatin-polycaprolactone fibrillar scaffolds intended for skin tissue engineering

Blends of natural and synthetic polymers have recently attracted great attention as scaffolds for tissue engineering applications due to their favorable biological and mechanical properties. Nevertheless, phase-separation of blend components is an important challenge facing the development of electrospun homogeneous fibrillar natural-synthetic polymers scaffolds; phase-separation can produce significant detrimental effects for scaffolds fabricated by electrospinning. In the present study, blends of gelatin (Gel; natural polymer) and polycaprolactone (PCL; synthetic polymer), containing 30 and 45 wt% Gel, were prepared using acetic acid as a 'green' sole solvent to straightforwardly produce appropriate single-step Gel-PCL solutions for electrospinning. Miscibility of Gel and PCL in the scaffolds was assessed and the morphology, chemical composition and structural and solid-state properties of the scaffolds were thoroughly investigated. Results showed that the two polymers proved miscible under the single-step solution process used and that the electrospun scaffolds presented suitable properties for potential skin tissue engineering applications. Viability, metabolic activity and protein expression of human fibroblasts cultured on the Gel-PCL scaffolds were evaluated using LIVE/DEAD (calcein/ethidium homodimer), MTT-Formazan and immunocytochemistry assays, respectively. In vitro results showed that the electrospun Gel-PCL scaffolds enhanced cell viability and proliferation in comparison to PCL scaffolds. Furthermore, scaffolds allowed fibroblasts expression of extracellular matrix proteins, tropoelastin and collagen Type I, in a similar way to positive controls. Results indicated the feasibility of the single-step solution process used herein to obtain homogeneous electrospun Gel-PCL scaffolds with Gel content ≥30 wt% and potential properties to be used as scaffolds for skin tissue engineering applications for wound healing.

Skin Structure-Function Relationships and the Wound Healing Response to Intrinsic Aging

Significance: Chronic wounds, such as diabetic foot ulcers, venous stasis ulcers, and pressure ulcers affect millions of Americans each year, and disproportionately afflict our increasingly older population. Older individuals are predisposed to wound infection, repeated trauma, and the development of chronic wounds. However, a complete understanding of how the attributes of aging skin affect the wound healing process has remained elusive. Recent Advances: A variety of studies have demonstrated that the dermal matrix becomes thinner, increasingly crosslinked, and fragmented with advanced age. These structural changes, as well as an increase in cell senescence, result in altered collagen fiber remodeling and increased stiffness. Studies combining mechanical testing with advanced imaging techniques are providing new insights into the relationships between these age-related changes. Emerging research into the mechanobiology of aging and the wound healing process indicate that the altered mechanical environment of aged skin may have a significant effect on age-related delays in healing. Critical Issues: The interpretation and synthesis of clinical studies is confounded by the effects of common comorbidities that also contribute to the development of chronic wounds. A lack of quantitative biomarkers of wound healing and age-related changes makes understanding structure-function relationships during the wound healing process challenging. Future Directions: Additional work is needed to establish quantitative and mechanistic relationships among age-related changes in the skin microstructure, mechanical function, and the cellular responses to wound healing.

The Impact of Diabetic Conditions and AGE/RAGE Signaling on Cardiac Fibroblast Migration

Diabetic individuals have an increased risk for developing cardiovascular disease due to stiffening of the left ventricle (LV), which is thought to occur, in part, by increased AGE/RAGE signaling inducing fibroblast differentiation. Advanced glycated end-products (AGEs) accumulate within the body over time, and under hyperglycemic conditions, the formation and accumulation of AGEs is accelerated. AGEs exert their effect by binding to their receptor (RAGE) and can induce myofibroblast differentiation, leading to increased cell migration. Previous studies have focused on fibroblast migration during wound healing, in which diabetics have impaired fibroblast migration compared to healthy individuals. However, the impact of diabetic conditions as well as AGE/RAGE signaling has not been extensively studied in cardiac fibroblasts. Therefore, the goal of this study was to determine how the AGE/RAGE signaling pathway impacts cell migration in non-diabetic and diabetic cardiac fibroblasts. Cardiac fibroblasts were isolated from non-diabetic and diabetic mice with and without functional RAGE and used to perform a migration assay. Cardiac fibroblasts were plated on plastic, non-diabetic, or diabetic collagen, and when confluency was reached, a line of migration was generated by scratching the plate and followed by treatment with pharmacological agents that modify AGE/RAGE signaling. Modification of the AGE/RAGE signaling cascade was done with ERK1/2 and PKC-ζ inhibitors as well as treatment with exogenous AGEs. Diabetic fibroblasts displayed an increase in migration compared to non-diabetic fibroblasts whereas inhibiting the AGE/RAGE signaling pathway resulted in a significant increase in migration. The results indicate that the AGE/RAGE signaling cascade causes a decrease in cardiac fibroblast migration and altering the pathway will produce alterations in cardiac fibroblast migration.

Handheld instrument for wound-conformal delivery of skin precursor sheets improves healing in full-thickness burns

The current standard of care for patients with severe large-area burns consists of autologous skin grafting or acellular dermal substitutes. While emerging options to accelerate wound healing involve treatment with allogeneic or autologous cells, delivering cells to clinically relevant wound topologies, orientations, and sizes remains a challenge. Here, we report the one-step in situ formation of cell-containing biomaterial sheets using a handheld instrument that accommodates the topography of the wound. In an approach that maintained cell viability and proliferation, we demonstrated conformal delivery to surfaces that were inclined up to 45° with respect to the horizontal. In porcine pre-clinical models of full-thickness burn, we delivered mesenchymal stem/stromal cell-containing fibrin sheets directly to the wound bed, improving re-epithelialization, dermal cell repopulation, and neovascularization, indicating that this device could be introduced in a clinical setting improving dermal and epidermal regeneration.

Small Leucine-Rich Proteoglycans in Skin Wound Healing

Healing of cutaneous wounds is a complex and well-coordinated process requiring cooperation among multiple cells from different lineages and delicately orchestrated signaling transduction of a diversity of growth factors, cytokines, and extracellular matrix (ECM) at the wound site. Most skin wound healing in adults is imperfect, characterized by scar formation which results in significant functional and psychological sequelae. Thus, the reconstruction of the damaged skin to its original state is of concern to doctors and scientists. Beyond the traditional treatments such as corticosteroid injection and radiation therapy, several growth factors or cytokines-based anti-scarring products are being or have been tested in clinical trials to optimize skin wound healing. Unfortunately, all have been unsatisfactory to date. Currently, accumulating evidence suggests that the ECM not only functions as the structural component of the tissue but also actively modulates signal transduction and regulates cellular behaviors, and thus, ECM should be considered as an alternative target for wound management pharmacotherapy. Of particular interest are small leucine-rich proteoglycans (SLRPs), a group of the ECM, which exist in a wide range of connecting tissues, including the skin. This manuscript summarizes the most current knowledge of SLRPs regarding their spatial-temporal expression in the skin, as well as lessons learned from the genetically modified animal models simulating human skin pathologies. In this review, particular focus is given on the diverse roles of SLRP in skin wound healing, such as anti-inflammation, pro-angiogenesis, pro-migration, pro-contraction, and orchestrate transforming growth factor (TGF)β signal transduction, since cumulative investigations have indicated their therapeutic potential on reducing scar formation in cutaneous wounds. By conducting this review, we intend to gain insight into the potential application of SLRPs in cutaneous wound healing management which may pave the way for the development of a new generation of pharmaceuticals to benefit the patients suffering from skin wounds and their sequelae.

Acupuncture and moxibustion stimulate fibroblast proliferation and neoangiogenesis during tissue repair of experimental excisional injuries in adult female Wistar rats

OBJECTIVE

To investigate the effects of acupuncture and moxibustion on the repair of excisional skin injuries on the back of adult female Wistar rats.

METHODS

90 animals were divided into three groups: C, control; A, acupuncture treatment (needled at traditional acupuncture points BL13, BL17 and ST36); M, moxibustion treatment (overlying same traditional acupuncture points). They were euthanased on days 7, 14 and 21 after injury for removal and preparation of tissue for analysis.

RESULTS

The treated groups (A and M) showed no changes regarding the structural analysis relative to the control (C) group. The total number of fibroblast cells in the A and M groups were significantly higher than those in the C group on days 14 and 21. The number of granulocytes was significantly less in the A and M groups compared with the C group on days 14 and 21. The total number of newly formed vessels increased on day 21 and was significantly higher in the A and M groups. The amount of birefringent collagen fibre detected on day 21 was significantly higher in the C group. The amount of glycosaminoglycan and hydroxyproline was similar between the groups. The amount of collagen I did not differ between the groups in any period, despite the increased amount detected over time. The amount of type III collagen did not differ between the groups but the detected amount decreased over the course of the experiment. The amount of transforming growth factor β1 (TGF-β1) and vascular endothelial growth factor (VEGF) in the A and M rats was similar but inferior to C rats across all experimental periods.

CONCLUSIONS

Acupuncture and moxibustion stimulated fibroblast proliferation and neoangiogenesis, and extended the period of collagen fibre reorganisation in the repair of excisional injuries in adult female rats.

Pholiota nameko Polysaccharides Promotes Cell Proliferation and Migration and Reduces ROS Content in H2O2-Induced L929 Cells

Pholiota nameko, a type of edible and medicinal fungus, is currently grown extensively for food and traditional medicine in China and Japan. It possesses various biological activities, such as anti-inflammatory, anti-hyperlipidemia and antitumor activities. However, P. nameko has rarely been discussed in the field of dermatology; identifying its biological activities could be beneficial in development of a new natural ingredient used in wound care. To evaluate its in vitro wound healing activities, the present study assessed the antioxidant and anti-collagenase activities of P. nameko polysaccharides (PNPs) prepared through fractional precipitation (40%, 60% and 80% (v/v)); the assessments were conducted using reducing power, hydroxyl radical scavenging activity, dichloro-dihydro-fluorescein diacetate and collagenase activity assays. The ability of PNPs to facilitate L929 fibroblast cell proliferation and migration was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and scratch assays. The findings indicated that, among all fractions, PNP-80 showed the best antioxidant and anti-collagenase activity, as measured by their reducing power (IC₅₀ of PNP-80 was 2.43 ± 0.17 mg/mL), the hydroxyl radical scavenging (IC₅₀ of PNP-80 was 2.74 ± 0.11 mg/mL) and collagenase activity assay, and significantly reduced cellular ROS content, compared with that of H₂O₂-induced L929 cells. Moreover, PNP-80 significantly promoted L929 fibroblast proliferation and migration, compared with the control group. Overall, we suggested that PNP-80 could be a promising candidate for further evaluation of its potential application on wound healing.

Anti-Photoaging Effect of Plant Extract Fermented with Lactobacillus buchneri on CCD-986sk Fibroblasts and HaCaT Keratinocytes

Ultraviolet (UV) exposure triggers the abnormal production of reactive oxygen (ROS) species and the expression of matrix metalloproteinases (MMPs) that are responsible for photoaging. Probiotics are widely used in healthcare and for immune enhancement. One probiotic, Lactobacillus buchneri is found in Kimchi. This study was aimed at assessing the anti-photoaging effect of plant extracts fermented with L. buchneri (PELB) to develop functional cosmetics. We investigated the anti-photoaging effect of PELB in a UVB-induced photoaging in vitro model and selected effective extracts using the elastase inhibition assay, ELISA for Type I procollagen and collagenase-1, and quantitative real time PCR. Normal human dermal fibroblasts and epidermal keratinocytes were pre-treated with PELB and exposed to UVB. We found that PELB decreased elastase activity and increased type I collagen expression in a UVB-induced photoaging in vitro model. In addition, PELB greatly reduced collagenase activity and MMP mRNA levels in a UVB-induced photoaging in vitro model. Furthermore, PELB promoted the expression of moisture factor and anti-oxidant enzymes in a UVB-induced photoaging in vitro model. These results indicated that the PELB could be potential candidates for the protective effects against UVB-induced photoaging. Overall, these results suggest that PELB might be useful natural components of cosmetic products.

FoxO3a depletion accelerates cutaneous wound healing by regulating epithelial‑mesenchymal transition through β‑catenin activation

The hysteresis of keratinocyte (KC) re-epithelialization is an important factor resulting in chronic wounds; however, the molecular mechanisms involved in this cellular response remain yet to be completely elucidated. The present study demonstrated the function of transcription factor Forkhead box O3a (FoxO3a) in KC growth and migration functional effects, resulting in restrained KC re-epithelialization during wound healing. In chronic wound tissue samples, the expression of FoxO3a was significantly increased when compared with the acute wound healing group (P<0.01). Overexpressing FoxO3a significantly inhibited, whereas silencing endogenous FoxO3a enhanced, the growth and migration of HaCaT cells in vitro. Further investigation revealed that FoxO3a negatively regulated matrix metalloproteinases 1 and 9, and increased the expression of tissue inhibitor of metalloproteinase 1. In addition, the upregulation of FoxO3a retarded, whereas the downregulation of FoxO3a accelerated, transforming growth factor-β1-induced epithelial-mesenchymal transition in HaCaT cells. Mechanistically, the overexpression of FoxO3a inactivated β-catenin signaling and markedly reduced the levels of nuclear β-catenin. These results reveal a novel mechanism of FoxO3a in regulating KC re-epithelialization, and provide novel targets for the prevention and treatment of chronic wounds.

Keratinocyte Function in Normal and Diabetic Wounds and Modulation by FOXO1

Diabetes has a significant and negative impact on wound healing, which involves complex interactions between multiple cell types. Keratinocytes play a crucial role in the healing process by rapidly covering dermal and mucosal wound surfaces to reestablish an epithelial barrier with the outside environment. Keratinocytes produce multiple factors to promote reepithelialization and produce factors that enhance connective tissue repair through the elaboration of mediators that stimulate angiogenesis and production of connective tissue matrix. Among the factors that keratinocytes produce to aid healing are transforming growth factor-β (TGF-β), vascular endothelial growth factor-A (VEGF-A), connective tissue growth factor (CTGF), and antioxidants. In a diabetic environment, this program is disrupted, and keratinocytes fail to produce growth factors and instead switch to a program that is detrimental to healing. Changes in keratinocyte behavior have been linked to high glucose and advanced glycation end products that alter the activities of the transcription factor, FOXO1. This review examines reepithelialization and factors produced by keratinocytes that upregulate connective tissue healing and angiogenesis and how they are altered by diabetes.

Leucine-activated nanohybrid biofilm for skin regeneration via improving cell affinity and neovascularization capacity

Nanohybrids containing amino acid are doped into biodegradable nanofibrous membranes, which improves the cell affinity, the migration and growth of fibroblasts, and the neovascularization capacity, comprehensively accelerating a rapid wound healing.

Human Dermal Fibroblast: A Promising Cellular Model to Study Biological Mechanisms of Major Depression and Antidepressant Drug Response

BACKGROUND

Human dermal fibroblasts (HDF) can be used as a cellular model relatively easily and without genetic engineering. Therefore, HDF represent an interesting tool to study several human diseases including psychiatric disorders. Despite major depressive disorder (MDD) being the second cause of disability in the world, the efficacy of antidepressant drug (AD) treatment is not sufficient and the underlying mechanisms of MDD and the mechanisms of action of AD are poorly understood.

OBJECTIVE

The aim of this review is to highlight the potential of HDF in the study of cellular mechanisms involved in MDD pathophysiology and in the action of AD response.

METHODS

The first part is a systematic review following PRISMA guidelines on the use of HDF in MDD research. The second part reports the mechanisms and molecules both present in HDF and relevant regarding MDD pathophysiology and AD mechanisms of action.

RESULTS

HDFs from MDD patients have been investigated in a relatively small number of works and most of them focused on the adrenergic pathway and metabolism-related gene expression as compared to HDF from healthy controls. The second part listed an important number of papers demonstrating the presence of many molecular processes in HDF, involved in MDD and AD mechanisms of action.

CONCLUSION

The imbalance in the number of papers between the two parts highlights the great and still underused potential of HDF, which stands out as a very promising tool in our understanding of MDD and AD mechanisms of action.

Tubulointerstitial nephritis antigen-like 1 deficiency alleviates age-dependent depressed ovulation associated with ovarian collagen deposition in mice

PURPOSE

This study aimed to examine whether the Tinagl1 might be associated with ovulation in aged females and reproductive age-associated fibrosis in the stroma of the ovary.

METHODS

To address the ovulatory ability and quality of ovulated oocytes, we induced ovulation by treatment with equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG) followed by in vitro fertilization. We also performed Picrosirius Red (PSR) staining to evaluate ovarian collagen deposition.

RESULTS

As compared to ovulation in 8- to 9-month-old Tinagl1flox/flox mice, the number of ovulated oocytes from Tinagl1flox/flox mice decreased in an age-dependent manner in mice more than 10-11 months old, whereas the ovulated oocyte numbers in Tinagl1 -/- mice decreased significantly at 14-15 months. In vitro fertilization followed by embryo culture demonstrated the normal developmental potential of Tinagl1-null embryos during the preimplantation period. PSR staining indicated that collagen was found throughout the ovarian stroma in an age-dependent manner in Tinagl1flox/flox females, whereas those distributions were delayed to 14-15 months in Tinagl1 -/- females. This timing was consistent with the delayed timing of age-related decline of ovulation in Tinagl1 -/- females.

CONCLUSIONS

The alleviation of age-associated depression of ovulation was caused by delayed ovarian collagen deposition in Tinagl1-null female mice.

Single-Cell Expression Variability Implies Cell Function

As single-cell RNA sequencing (scRNA-seq) data becomes widely available, cell-to-cell variability in gene expression, or single-cell expression variability (scEV), has been increasingly appreciated. However, it remains unclear whether this variability is functionally important and, if so, what are its implications for multi-cellular organisms. Here, we analyzed multiple scRNA-seq data sets from lymphoblastoid cell lines (LCLs), lung airway epithelial cells (LAECs), and dermal fibroblasts (DFs) and, for each cell type, selected a group of homogenous cells with highly similar expression profiles. We estimated the scEV levels for genes after correcting the mean-variance dependency in that data and identified 465, 466, and 364 highly variable genes (HVGs) in LCLs, LAECs, and DFs, respectively. Functions of these HVGs were found to be enriched with those biological processes precisely relevant to the corresponding cell type’s function, from which the scRNA-seq data used to identify HVGs were generated—e.g., cytokine signaling pathways were enriched in HVGs identified in LCLs, collagen formation in LAECs, and keratinization in DFs. We repeated the same analysis with scRNA-seq data from induced pluripotent stem cells (iPSCs) and identified only 79 HVGs with no statistically significant enriched functions; the overall scEV in iPSCs was of negligible magnitude. Our results support the “variation is function” hypothesis, arguing that scEV is required for cell type-specific, higher-level system function. Thus, quantifying and characterizing scEV are of importance for our understating of normal and pathological cellular processes.

Silk-CNT Mediated Fibroblast Stimulation toward Chronic Wound Repair

Background

Diabetic patients suffer from chronic wounds partly due to altered function of fibroblasts. Fibroblasts of diabetic patients synthesize collagen I (COLI) at a much higher level than collagen III (COLIII), resulting in delayed tissue granulation and, consequently, a delay in the overall wound healing process.

Methods

We aimed to revive the matrix protein productivity of diabetic fibroblasts by employing aligned, electrically conductive and biocompatible spider silk-CNT fibers as a cell culture matrix to mediate the electrical stimulation of fibroblasts to induce cell polarization and activation.

Results

A 5.2 and 42.7 fold increase in COLI and COLIII production was induced in diabetic fibroblasts. The stimulated cells synthesized a substantially high level of COLIII to reduce the abnormally high COLI/COLIII ratio, and the matrix metalloproteinases expression was markedly suppressed. The protein expression profile was consistent with favorable wound healing. The modulation effect was also demonstrated in normal fibroblasts of healthy individuals, suggesting that the developed method can be utilized generally for connective tissue repair. Silkworm silk-CNT fibers corroborated similar effects on restoring the function of diabetic fibroblasts.

Conclusions

The approach of using an engineered biopolymer matrix to remedy dysfunctional fibroblasts of patients offers the opportunity of developing personalized cell therapy for noninvasive treatments and inspires the design of multi-functional biometrics for effective tissue regeneration.

Beta-caryophyllene enhances wound healing through multiple routes

Beta-caryophyllene is an odoriferous bicyclic sesquiterpene found in various herbs and spices. Recently, it was found that beta-caryophyllene is a ligand of the cannabinoid receptor 2 (CB2). Activation of CB2 will decrease pain, a major signal for inflammatory responses. We hypothesized that beta-caryophyllene can affect wound healing by decreasing inflammation. Here we show that cutaneous wounds of mice treated with beta-caryophyllene had enhanced re-epithelialization. The treated tissue showed increased cell proliferation and cells treated with beta-caryophyllene showed enhanced cell migration, suggesting that the higher re-epithelialization is due to enhanced cell proliferation and cell migration. The treated tissues also had up-regulated gene expression for hair follicle bulge stem cells. Olfactory receptors were not involved in the enhanced wound healing. Transient Receptor Potential channel genes were up-regulated in the injured skin exposed to beta-caryophyllene. Interestingly, there were sex differences in the impact of beta- caryophyllene as only the injured skin of female mice had enhanced re-epithelialization after exposure to beta-caryophyllene. Our study suggests that chemical compounds included in essential oils have the capability to improve wound healing, an effect generated by synergetic impacts of multiple pathways.

Bioengineered Platforms for Chronic Wound Infection Studies: How Can We Make Them More Human-Relevant?

Chronic wound infections are an important cause of delayed wound healing, posing a significant healthcare burden with consequences that include hospitalization, amputation, and death. These infections most often take the form of three-dimensional biofilm communities, which are notoriously recalcitrant to antibiotics and immune clearance, contributing to the chronic wound state. In the chronic wound microenvironment, microbial biofilms interact closely with other key components, including host cellular and matrix elements, immune cells, inflammatory factors, signaling components, and mechanical cues. Intricate relationships between these contributing factors not only orchestrate the development and progression of wound infections but also influence the therapeutic outcome. Current medical treatment for chronic wound infections relies heavily on long-term usage of antibiotics; however, their efficacy and reasons for failure remain uncertain. To develop effective therapeutic approaches, it is essential to better understand the complex pathophysiology of the chronic wound infection microenvironment, including dynamic interactions between various key factors. For this, it is critical to develop bioengineered platforms or model systems that not only include key components of the chronic wound infection microenvironment but also recapitulate interactions between these factors, thereby simulating the infection state. In doing so, these platforms will enable the testing of novel therapeutics, alone and in combinations, providing insights toward composite treatment strategies. In the first section of this review, we discuss the key components and interactions in the chronic wound infection microenvironment, which would be critical to recapitulate in a bioengineered platform. In the next section, we summarize the key features and relevance of current bioengineered chronic wound infection platforms. These are categorized and discussed based on the microenvironmental components included and their ability to recapitulate the architecture, interactions, and outcomes of the infection microenvironment. While these platforms have advanced our understanding of the underlying pathophysiology of chronic wound infections and provided insights into therapeutics, they possess certain insufficiencies that limit their clinical relevance. In the final section, we propose approaches that can be incorporated into these existing model systems or developed into future platforms developed, thus enhancing their biomimetic and translational capabilities, and thereby their human-relevance.

The analgesic hybrid of dermorphin/substance P and analog of enkephalin improve wound healing in streptozotocin-induced diabetic rats

The purpose of this study was to investigate the effect of the peptide analgesic hybrid compounds: AWL3106 analog of dermorphin and substance P (7-11), and biphalin enkephalin analog on wound healing in streptozotocin-induced diabetic rats. The diabetes was induced in 6-7 week-old male Wistar rats by intraperitoneal injection of streptozotocin. After 70 days, the wounds were created on the back of the rats and then, once a day for 21 days, the dressing containing lanolin ointment, 10% of keratin scaffolds, and 1 mM of AWL3106 or biphalin was applied. The wounds histology were analyzed by hematoxylin and eosin staining. The orientation and organization of collagen was analyzed by Masson's trichome staining. The number of macrophages, blood vessels, and fibroblasts were visualized by CD68, CD34, and vimentin immunoreactivity, respectively. Our results demonstrated that the wound area of AWL3106- and biphalin-treated groups was greatly reduced (up to 47% on the 7 day) in comparison with untreated diabetic groups. The immunohistochemical staining of macrophages demonstrated that AWL3106 and biphalin accelerated inflammatory progression and subsequently decreased persistent inflammation. The histological analysis showed that the structure of tissue in the groups under the study was very similar to the one of wound tissue in N-DM group. The H&E and Masson's trichome staining demonstrated that the orientation and organization of collagen as well as the number and shape of blood vessels were better in 3106- and BIF-treated group than in DM group. In conclusion, the obtained data suggested that our hybrid peptides enhanced wound healing, particularly by accelerating the inflammatory phase and promoted the wound closure.

Effects and formulation of silver nanoscaffolds on cytotoxicity dependent ion release kinetics towards enhanced excision wound healing patterns in Wistar albino rats

Wound tissue regeneration and angiogenesis are dynamic processes that send physiological signals to the body. Thus, designing novel nanoscaffolds by understanding their surface modifications and toxicological response in a biological system with a potent anti-inflammatory response is a viable solution. In this respect, inspired by the surface chemistry, in the present work we focus on the chemical optimization of silver nanoscaffolds using surface cappings in order to understand their kinetic release behaviour in simulated wound fluids (SWF), to analyze their blood compatibility in human lymphocytes and erythrocytes and then embed them in a chitosan-agarose matrix (CAM) as a productive drug delivery system to evaluate in vivo excision wound tissue regeneration efficiency in Wistar rats. In this regard, polyvinyl alcohol capped silver nanocomposites (PVA-AgNPs) exhibit a dominant antibacterial efficacy with the sustained and controlled release of silver ions and percentage cell mortality and percentage hemolysis of only 10% and 16% compared with uncapped-AgNPs or silver bandaids (SBDs). Also, PVA-AgNP impregnated CAM (PVA-CAM) shows positive effects through their anti-inflammatory and angiogenic properties, with a nearly 95% healing effect within 9 days. The complete development of collagen and fibroblast constituents was also monitored in PVA-CAM by hematoxylin & eosin (H & E) and Masson trichrome (MT) staining. These results provide a clear insight into the development of a potent therapeutic formulation using CAM as a scaffold incorporated with surface functionalized PVA-AgNPs as a bioeffective and biocompatible polymer for the fabrication of efficacious silver wound dressing scaffolds in clinical practice.

Autologous micrograft accelerates endogenous wound healing response through ERK-induced cell migration

Defective cell migration causes delayed wound healing (WH) and chronic skin lesions. Autologous micrograft (AMG) therapies have recently emerged as a new effective and affordable treatment able to improve wound healing capacity. However, the precise molecular mechanism through which AMG exhibits its beneficial effects remains unrevealed. Herein we show that AMG improves skin re-epithelialization by accelerating the migration of fibroblasts and keratinocytes. More specifically, AMG-treated wounds showed improvement of indispensable events associated with successful wound healing such as granulation tissue formation, organized collagen content, and newly formed blood vessels. We demonstrate that AMG is enriched with a pool of WH-associated growth factors that may provide the starting signal for a faster endogenous wound healing response. This work links the increased cell migration rate to the activation of the extracellular signal-regulated kinase (ERK) signaling pathway, which is followed by an increase in matrix metalloproteinase expression and their extracellular enzymatic activity. Overall we reveal the AMG-mediated wound healing transcriptional signature and shed light on the AMG molecular mechanism supporting its potential to trigger a highly improved wound healing process. In this way, we present a framework for future improvements in AMG therapy for skin tissue regeneration applications.

Needle-Free Injection of Exosomes Derived from Human Dermal Fibroblast Spheroids Ameliorates Skin Photoaging

Human dermal fibroblasts (HDFs), the main cell population of the dermis, gradually lose their ability to produce collagen and renew intercellular matrix with aging. One clinical application for the autologous trans-dermis injection of HDFs that has been approved by the Food and Drug Administration aims to refine facial contours and slow down skin aging. However, the autologous HDFs used vary in quality according to the state of patients and due to many passages they undergo during expansion. In this study, factors and exosomes derived from three-dimensional spheroids (3D HDF-XOs) and the monolayer culture of HDFs (2D HDF-XOs) were collected and compared. 3D HDF-XOs expressed a significantly higher level of tissue inhibitor of metalloproteinases-1 (TIMP-1) and differentially expressed miRNA cargos compared with 2D HDF-XOs. Next, the efficacy of 3D HDF-XOs in inducing collagen synthesis and antiaging was demonstrated in vitro and in a nude mouse photoaging model. A needle-free injector was used to administer exosome treatments. 3D HDF-XOs caused increased procollagen type I expression and a significant decrease in MMP-1 expression, mainly through the downregulation of tumor necrosis factor-alpha (TNF-α) and the upregulation of transforming growth factor beta (TGF-β). In addition, the 3D-HDF-XOs group showed a higher level of dermal collagen deposition than bone marrow mesenchymal stem cell-derived exosomes. These results indicate that exosomes from 3D cultured HDF spheroids have anti-skin-aging properties and the potential to prevent and treat cutaneous aging.

Elevated Thrombospondin 2 Contributes to Delayed Wound Healing in Diabetes

Impaired wound healing is a major complication of diabetes, and despite the associated risks, treatment strategies for diabetic wounds remain limited. This is due, in part, to an incomplete understanding of the underlying pathological mechanisms, including the effects of hyperglycemia on components of the extracellular matrix (ECM). In the current study, we explored whether the expression of thrombospondin 2 (TSP2), a matricellular protein with a demonstrated role in response to injury, was associated with delayed healing in diabetes. First, we found that TSP2 expression was elevated in diabetic mice and skin from patients with diabetes. Then, to determine the contribution of TSP2 to impaired healing in diabetes, we developed a novel diabetic TSP2-deficient model. Though the TSP2-deficient mice developed obesity and hyperglycemia comparable with diabetic control mice, they exhibited significantly improved healing, characterized by accelerated reepithelialization and increased granulation tissue formation, fibroblast migration, and blood vessel maturation. We further found that hyperglycemia increased TSP2 expression in fibroblasts, the major cellular source of TSP2 in wounds. Mechanistically, high glucose increased activation of the hexosamine pathway and nuclear factor-κB signaling to elevate TSP2 expression. Our studies demonstrate that hyperglycemia-induced TSP2 expression contributes to impaired healing in diabetes.

Potential of Distilled Liquid Smoke Derived from Coconut (Cocos nucifera L) Shell for Traumatic Ulcer Healing in Diabetic Rats

Objective Distilled liquid smoke (DLS) is a result of coconut processing by-product that not only serves as a natural food preservative but also has a promising therapeutic effect. The healing potential of DLS derived from coconut ( Cocos nucifera L) shell was investigated on a traumatic ulcer with the diabetic rat.

Materials and Methods DLS was analyzed the component by gas chromatograph mass spectrometry. Diabetic condition was induced by alloxan in 55 male Wistar rats. Ten mm of traumatic ulcer was made along the labial fornix incisive inferior after the diabetic condition was confirmed. Then DLS coconut shell, benzydamine hydrochloride, and sterile distilled water were applied topically for 3, 5, and 7 days. The potential healing was evaluated based on the expression of nuclear factor kappa beta (NFκB) and tumor necrosis factor alpha (TNF-α) on macrophages using immunohistochemical staining and the amount of collagen using Masson Trichome staining. The difference between each group was analyzed using one-way analysis of variance. The least significant difference test is used to determine the significant difference ( p < 0.05).

Results The major compounds found were phenol (36.6%), 2-methoxyphenol (guaiacol) (25.2%), furfural (17.8%), and 4-ethyl-2-methoxyphenol (3.5%) with 28 other minor constituents. The lowest NFκB and TNF-α expression on macrophage was observed by topical application of DLS derived from coconut shell for 3, 5, and 7 days of treatment. The amount of collagen was increased and indicated by the highest result of DLS compared to others.

Conclusion The DLS derived from coconut ( Cocos nucifera L) shell was able to improve traumatic ulcer healing in a person with diabetes.