Keratinocyte-fibroblast interactions in wound healing

Role of non-exponential reversal times in aggregation models of bacterial populations

Individual bacteria typically follow somewhat simple rules of motion, but collective behavior can exhibit complex behavioral patterns. For instance, the formation and dispersal of aggregates of reversing bacteria in biofilms are primarily driven by coordinated motion among cells. Many mathematical models of aggregation assume that cells have no memory, e.g., the time between their behavior changes, such as direction reversals, is exponentially distributed. However, in practice, the distribution is quite distinct from exponential. Therefore, in this paper, we analyze numerically the importance of non-exponential reversal times in 1D agent-based and kinetic models of aggregation. In particular, we consider these models in a practical parameter regime by fitting a Gamma distribution to represent the run times of myxobacteria and study their collective behavior with exponential and non-exponential reversal times. We demonstrate that non-exponential reversal times aid aggregation and result in tighter aggregates. We compare and contrast the behavior of agent-based and kinetic models that consider aggregation driven by chemotaxis. Thus, incorporating non-exponential reversal times into models of aggregation can be particularly important for reproducing experimental data, such as aggregate persistence and dispersal. These results provide a simple example of how the existence of memory helps bacteria coordinate their behaviors.

The role of exosomes derived from various sources in facilitating the healing of chronic refractory wounds

Chronic refractory wounds (CRWs) represent a common and challenging issue in clinical practice, including diabetic foot ulcers, pressure ulcers, venous ulcers, and arterial ulcers. These wounds significantly impact patients' quality of life and may lead to severe consequences such as amputation. Their treatment requires a comprehensive consideration of both the patient's overall physical condition and the local wound situation. The major challenges in treatment include complex pathogenesis, a long treatment cycle, a high recurrence rate, and heavy economic pressure on the patients. Exosomes represent an emerging therapeutic modality with characteristics such as low immunogenicity, good biostability, and high targeting efficiency in the treatment of diseases. Exosomes derived from different sources exhibit heterogeneity, demonstrating their respective advantages and unique properties in treatment. This article delves into the potential applications and mechanisms of action of exosomes from various sources in the treatment of CRWs, aiming to provide new perspectives and ideas for the management of such wounds.

Divergent effects of vitamin D3 on human dermal fibroblasts and keratinocytes in wound repair: Implications for therapeutic targeting in tissue remodelling and scarring

BACKGROUND

Vitamin D is known to regulate inflammation and immunity, suggesting it may play a role in wound healing. However, its mechanism of action in key skin cell types-keratinocytes and fibroblasts-involved in wound repair is poorly understood.

OBJECTIVES

This study aimed to elucidate the impact of vitamin D3 and its precursors on keratinocyte and fibroblast behaviour during wound healing using human ex vivo skin explant and primary cell culture models.

METHODS

The rate of closure of incisional wounds made on human ex vivo skin explants treated with the vitamin D3 precursor, cholecalciferol, or the active form 1,25(OH)2D3 was measured over 6 days in culture. Primary cultures of human keratinocytes and dermal fibroblasts were propagated from female facial skin, and changes in gene expression and physiological responses to cholecalciferol or 1,25(OH)2D3 were assessed using various techniques, including scratch wound assays, quantitative reverse transcription polymerase chain reaction, zymography, and immunocytochemistry.

RESULTS

1,25(OH)2D3 significantly increased the early wound closure rate in ex vivo human skin explants, while cholecalciferol had no effect. 1,25(OH)2D3 accelerated keratinocyte migration but inhibited fibroblast migration and their transition into pro-fibrotic myofibroblasts, reducing extracellular matrix remodelling. Using small interfering RNA, it was established that responses were mediated by vitamin D receptor signalling.

CONCLUSIONS

This study highlighted the divergent effects of vitamin D on keratinocyte and fibroblast wound responses, i.e., promoting re-epithelialisation, while potentially suppressing aberrant fibrosis. Optimising vitamin D status may facilitate wound repair while minimising scarring, which has implications for treating non-healing wounds and excessive scarring disorders.

Topical Administration of Vitamin D2 Combined with Colloidal Silver Nanoparticles Promotes Wound Repair and Protection Against Skin Irritation and UVB Irradiation in 3D Reconstructed Human Skin Models

Background/Objectives: There is a great demand for novel, multipurpose, natural skin-care products in the global skin repair and sun protection markets. Within this framework, the potential benefits of topical Vitamin D2 (VD2) administration in combination with silver nanoparticles (AgNPs) were examined. Methods: Evaluating the efficacy of the VD2+AgNP cream in wound healing, skin irritation and UVB irradiation protection necessitated preclinical testing using reconstructed human skin equivalent models (prepared from human foreskins) containing both a fully stratified epidermal layer and underlying dermis. Results: Application of the cream significantly improved wound healing by stimulating keratinocyte re-epithelialization and dermal fibroblast migration in models subjected to full-thickness (scratch and biopsy punch) wounds, compared to untreated models. The VD2+AgNP cream, administered prior to the induction of skin irritation by 5% sodium dodecyl sulfate (SDS) afforded protection by ameliorating cell viability epidermal thickness and interleukin-1alpha levels. UVB exposure (50 mJ/cm2) significantly reduced cell viability and epidermal thickness (associated with increased epidermal breakage), as well as basal layer Ki67 and supra-basal layer involucrin expression, compared to the CTRL sham-irradiated models. The cream administered prior to UVB irradiation (protective capacity) showed greater efficacy in minimizing epidermal damage. This was reflected by significantly higher Ki67 and involucrin expression, as well as lower epidermal breakage, compared to models where the cream was applied following UVB irradiation (curative capacity). Conclusions: The VD2+AgNP cream shows multipurpose potential in skin protection. The underlying molecular mechanisms remain to be investigated.

A bioactive three-layered skin substitute based on ECM components effectively promotes skin wound healing and regeneration

To overcome the limitations of conventional skin tissue engineering (TE), 3D biofabrication approaches are being developed. However, tissue mimicry should be further improved in skin models. Here, we developed and characterized biomimetic hydrogels to obtain a biofabricated three-layered (BT) skin substitute based on the main components found in the epidermal, dermal, and hypodermal skin layers. Hydrogels for dermal and hypodermal skin layers were based on a mix of agarose and type I collagen, supplemented with skin-related extracellular matrix (ECM) components (dermatan sulfate, hyaluronic acid, and elastin) and loaded with human dermal fibroblasts (hDFs) or human mesenchymal stem/stromal cells (hMSCs), respectively. The epidermal hydrogel was formulated using type I collagen supplemented with keratin and sphingolipids, and seeded with human epidermal keratinocytes (hEKs). Physicochemical results revealed adequate viscosity, gelling times, and pH for each hydrogel solution. The BT Skin also showed good swelling and degradation kinetics, and mechanical properties in a similar range of human skin. The hydrogels and BT Skin demonstrated stable cell viability and metabolic activity, as well as intercellular communication through the release of growth factors. Moreover, the BT Skin demonstrated controlled inflammation in vivo, and produced results comparable to autografting in a mouse skin wound model. This bioactive and biomimetic three-layered BT Skin has a composition that attempts to mimic the natural ECM of the skin, formulated with the characteristic cells and biomolecules present in each skin layer, and offers promising properties for its clinical application in the treatment of patients with skin injuries.

Self-assembled nanoparticles of hybrid elastin-like and Oncostatin M polymers for improved wound healing

Oncostatin M (OSM) is a pleiotropic cytokine that can significantly enhance wound healing. Here, we report on the use of nanoparticles (NPs) formulated from a genetically engineered A200_hOSM protein polymer, which combines an elastin-like recombinamer (A200) with human OSM (hOSM) in the same molecule, aiming at enhancing wound healing processes. A200_hOSM NPs were obtained by self-assembly and evaluated for their bioactivity in human keratinocytes and fibroblasts. The NPs demonstrated superior efficacy in promoting cell proliferation in a dose-dependent manner, exhibiting nearly threefold greater proliferation at 48 and 72 h, compared to cells treated with commercial hOSM. Moreover, the NPs stimulated cell migration and collagen production through activation of JAK/STAT3 signaling. They also promoted the production of IL-6 and IL-8, pro-inflammatory cytokines with a critical role for wound healing. Promotion of keratinocyte proliferation and differentiation were further validated in non-commercial 3D skin equivalents. The A200_hOSM NPs revealed potential in accelerating wound healing, evidenced by reduced wound size and a thicker epidermal layer. This system represents a significant advancement in the field of bioinspired biomaterials by improving cytokine bioavailability, allowing for localized therapy and offering a cost-effective strategy for employing hOSM in wound healing management.

A Randomised Controlled Clinical Study Comparing the Efficacy and Safety of an Autologous Standardised Leukocyte-Poor Platelet Gel With Standard Care for the Treatment of Chronic Neuropathic Diabetic Foot Ulcers

This randomised controlled clinical trial compared the efficacy of a standardised autologous platelet gel (RegenWound gel) (n = 48) with a standard care treatment (hydrocellular or hydrocolloid dressing) (n = 48) for the treatment of hard-to-heal foot ulcers in type 1 or 2 diabetes mellitus patients > 18 years old. The primary outcomes were the percentage of ulcers healed 6 weeks after treatment commenced. The secondary outcomes were the average healing time, the time course of the healing process, the local tolerance, and the acceptability of the treatment by the patient compared to the standard treatment. At the 6 weeks end-of-treatment visit (ETV), 56.5% of the patients in the RegenWound gel group and 20.0% of the patients in the control group had completely healed. Healing continued to evolve after the ETV and reached 77.3% at end-of-study visit 2 (12 weeks) in the RegenWound gel group, compared to 35.1% for the control group. The treatment was well tolerated and safe. RegenWound gel could be an effective treatment for diabetic foot ulcers, with most patients being healed within 6 weeks of treatment, and on average 1 to 2 treatments being needed. Trial Registration: ISRCTN10032417.

Differential Temperature-Induced Responses in Immortalized Oral and Skin Keratinocytes

The epidermis of the skin and oral mucosa is constantly exposed to various environmental stimuli, including temperature changes. In particularly extreme conditions, such as excess heat or cold, significant injury may occur. Oral and skin keratinocytes exhibit tissue-specific differences in wound healing outcomes and the transcriptomic response to injury. This study investigated if skin and oral keratinocytes also have differential responses to heat- and cold-induced injury. Oral keratinocytes (TIGKs) were found to exhibit an enhanced viability following heat-induced injury compared to skin keratinocytes (HaCaTs). However, there were no discernible differences between skin and oral keratinocyte viability following cold-induced injury. To examine the transcriptomic differences between skin and oral keratinocytes in response to temperature-induced injury, we generated an mRNA-sequencing gene expression dataset. Differentially expressed genes (DEGs) including heat shock proteins (HSPs) were identified between HaCaTs and TIGKs at baseline (37 °C) and after heat- (60 °C) or cold-induced (-25 °C) injury. Our comparative analyses suggest that skin and oral keratinocytes exhibit transcriptomic differences at baseline and in their responses to heat or cold exposure. The enhanced heat tolerance of TIGKs relative to HaCaTs may be due to an advantageous expression of a subset of HSPs at baseline in TIGKs. Our work also provides a source of skin and oral keratinocyte gene expression data following heat- and cold-induced injury that can be used for future analyses.

Silk Fibroin Surface Engineering Using Phase Separation Approaches for Enhanced Cell Adhesion and Proliferation

Due to excellent mechanical properties and biocompatibility, materials based on silk fibroin are increasingly included in advanced biomedical research and applications. However, their poor supporting properties for cell adhesion and proliferation represent limiting factors of the utilization. To eliminate this deficiency, we developed a series of phase-separation approaches allowing for tunable texturing of planar and 3D printed fibroin surfaces from nano to macro levels. The formation of surface structures presented is based on a combination of good and poor solvents, whereas no potentially problematic templates or additives, diminishing biocompatibility of the resulting material, are required. A critical factor in obtaining and scaling of the textures is control over the degree of transformation of fibroin secondary structures between prevalently amorphous Silk I and semicrystalline Silk II forms before and during surface treatment. Employing a set of optimized procedures, selectively or hierarchically structured fibroin surfaces can be prepared at the nano, micro, and macro level, which are characterized by long-term stability in physiological environments, allowing enhanced adhesion and proliferation of human keratinocytes as well as skin fibroblast cultivations.

CDK1-loaded extracellular vesicles promote cell cycle to reverse impaired wound healing in diabetic obese mice

Small extracellular vesicles (sEVs) mediate intercellular signaling to coordinate the proliferation of cell types that promote re-epithelialization of skin following injury. Cyclin-dependent kinase 1 (CDK1) drives cell division and is a key regulator of entry to the cell cycle. To understand the potential of sEV-mediated delivery of CDK1 to reverse impaired wound healing, we generated CDK1-loaded sEVs (CDK1-sEVs) and evaluated their ability to mediate cell proliferation, re-epithelialization, and downstream signaling responses in the wound bed. We found that treatment of human keratinocytes with CDK1-sEVs increased phosphorylation of the CDK1 target, eukaryotic translation inhibition factor 4E-binding protein 1 (4E-BP1), and histone H3 within 24 h via AKT and ERK phosphorylation, driving increased proliferation and cell migration. Treatment of the wound bed of diabetic obese mice, a model of delayed wound healing, with a single dose of CDK1-sEVs accelerated wound closure, increased re-epithelialization, and promoted the proliferation of keratinocytes. These studies show that delivery of CDK1 by sEVs can stimulate selective and transient proliferation of cell types that increase re-epithelialization and promote proliferation of keratinocytes to accelerate wound healing.

Electrospinning strategies targeting fibroblast for wound healing of diabetic foot ulcers

The high incidence and prevalence of diabetic foot ulcers (DFUs) present a substantial clinical and economic burden, necessitating innovative therapeutic approaches. Fibroblasts, characterized by their intrinsic cellular plasticity and multifunctional capabilities, play key roles in the pathophysiological processes underlying DFUs. Hyperglycemic conditions lead to a cascade of biochemical alterations that culminate in the dysregulation of fibroblast phenotype and function, which is the primary cause of impaired wound healing in DFUs. Biomaterials, particularly those engineered at the nanoscale, hold significant promise for enhancing DFU treatment outcomes. Electrospun nanofiber scaffolds, with their structural and compositional similarities to the natural extracellular matrix, serve as an effective substrate for fibroblast adhesion, proliferation, and migration. This review comprehensively summarizes the biological behavior of fibroblasts in DFUs and the mechanism mediating wound healing. At the same time, the mechanism of biological materials, especially electrospun nanofiber scaffolds, to improve the therapeutic effect by regulating the activity of fibroblasts was also discussed. By highlighting the latest advancements and clinical applications, we aim to provide a clear perspective on the future direction of DFU treatment strategies centered on fibroblast-targeted therapies.

Effects of Chlorella protothecoides-derived polydeoxyribonucleotides on skin regeneration and wound healing

The skin acts as a crucial barrier and, upon injury, initiates complex wound-healing processes involving various cell types. Polydeoxyribonucleotides (PDRNs) are well-known for their efficacy in enhancing skin regeneration and wound healing. This study sought to investigate the effectiveness of PDRNs derived from Chlorella protothecoides, a sustainable and scalable microalgal source, in promoting skin regeneration and wound healing. Keratinocytes and fibroblasts were used for assessing the impact of PDRNs on cell proliferation, migration, collagen synthesis, and angiogenesis. Gene expression and associated signaling pathways were also examined using RT-qPCR and Western blot analyses. Our findings demonstrated that PDRNs significantly enhanced the proliferation and migration of skin cells, upregulated growth arrest specific 6 (GAS6) and hepatocyte growth factor (HGF) expression, and increased collagen synthesis by modulating collagen type I alpha 1 (COLIA1) expression. Additionally, PDRNs enhanced angiogenesis by promoting vascular endothelial growth factor (VEGF) expression and activation of ERK, AKT, β-catenin and STAT3 pathways via an adenosine A2A receptor (A2AR)-dependent mechanism. These findings suggest that microalgal-derived PDRNs have significant potential as sustainable and effective agents for clinical and cosmetic applications aimed at improving skin health and wound healing.

Hydrogen-Releasing Micromaterial Dressings: Promoting Wound Healing by Modulating Extracellular Matrix Accumulation Through Wnt/β-Catenin and TGF-β/Smad Pathways

Background: Wound healing is a complex and intricate biological process that involves multiple systems within the body and initiates a series of highly coordinated responses to repair damage and restore integrity and functionality. We previously identified that breathing hydrogen can significantly inhibit early inflammation, activate autologous stem cells, and promote the accumulation of extracellular matrix (ECM). However, the broader functions and downstream targets of hydrogen-induced ECM accumulation and tissue remodeling are unknown in the wound-healing process. Methods: Consequently, this thesis developed a hydrogen sustained-release dressing based on a micro storage material and reveals the mechanism of hydrogen in treating wound healing. Upon encapsulating the hydrogen storage materials, magnesium (Mg), and ammonia borane (AB), we found that SiO2@Mg exhibits superior sustained-release performance, while SiO2@AB demonstrates a higher hydrogen storage capacity. We used a C57/BL6 mouse full-thickness skin defect wound model to analyze and compare different hydrogen dressings. Results: It was identified that hydrogen dressings can significantly improve the healing rate of wounds by promoting epithelialization, angiogenesis, and collagen accumulation in wound tissue, and that the effect of slow-release dressings is better than of non-slow-release dressings. We also found that hydrogen dressing can promote transcriptome-level expression related to cell proliferation and differentiation and ECM accumulation, mainly through the Wnt1/β-catenin pathway and TGF-β1/Smad2 pathway. Conclusions: Overall, these results provide a novel insight into the field of hydrogen treatment and wound healing.

Improving partial-thickness burn pain and outcomes using cultured epithelial allografts or highly concentrated surfactant-based dressings

OBJECTIVE

The prevention and treatment of burn wounds has improved over the years, leading to decreased incidence, severity and mortality. However, burn injuries, particularly partial-thickness burns, have a painful treatment course which, if not optimised, can cause undue suffering to patients and prolonged recovery. Although silver sulfadiazine has been the most commonly accepted treatment for partial-thickness burns due to its strong hindrance of infection, wide availability and low cost, it requires daily dressing changes which are labour intensive and painful. Exploring alternative techniques, such as using cultured keratinocytes, to prevent and treat burn wounds may provide a path to better optimising the path to recovery.

METHOD

This paper presents two cases that use two alternative treatments, either PluroGel (a gel surfactant, Medline Industries, US) or cultured keratinocytes, in the treatment of partial-thickness burns to minimise pain and enhance treatment experience.

RESULTS

Using surfactant-based treatments, such as the gel surfactant, in partial-thickness burns exhibited prohealing outcomes via enhanced antimicrobial effects, a strengthened physical barrier and cell salvage.

CONCLUSION

Using cultured keratinocytes and a highly concentrated surfactant may achieve more rapid re-epithelialisation of partial-thickness burn wounds. These alternative techniques may offer significant advancement in the quality of care in burn injury treatment.

MSC-EVs and UCB-EVs promote skin wound healing and spatial transcriptome analysis

Extracellular vesicles (EVs) are important paracrine mediators derived from various cells and biological fluids, including plasma, that are capable of inducing regenerative effects by transferring bioactive molecules such as microRNAs (miRNAs). This study investigated the effect of mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) isolated from umbilical cord blood and human umbilical cord plasma-derived extracellular vesicles (UCB-EVs) on wound healing and scar formation reduction. Spatial transcriptomics (ST) was used to study the effects of MSC-EVs and UCB-EVs on the heterogeneity of major cell types and wound healing pathways in mouse skin tissue. MSC-EVs and UCB-EVs were isolated using ultracentrifugation and identified using transmission electron microscopy, nanoparticle tracking analysis, and western blot. The effects of MSC-EVs and UCB-EVs on human dermal fibroblast-adult cell (HDF-a) migration and proliferation were evaluated using cell scratch assays, cell migration assays, and cell proliferation assays. In vivo, MSC-EVs and UCB-EVs were injected around full-cut wounds to evaluate their efficacy of wound healing by measuring wound closure rates and scar width and performing histological analysis. ST was performed on skin tissue samples from mice in each group after wound healing to analyze the heterogeneity of major cell types compared with the control group and investigate potential mechanisms affecting wound healing and scar formation. In vitro experiments demonstrated that MSC-EVs and UCB-EVs promoted the proliferation and migration of HDF-a cells. Local injection of MSC-EVs and UCB-EVs into the periphery of a mouse skin wound accelerated re-epithelialization, promoted wound healing, and reduced scar width. ST analysis of skin tissue from each group after wound healing revealed that MSC-EVs and UCB-EVs reduced the relative expression of marker genes in myofibroblasts, regulated wound healing, and decreased scar formation by reducing the expression of the TGF-β signaling pathway and increasing the expression of the Wnt signaling pathway. The results suggest that MSC-EVs and UCB-EVs play a significant role in the activity of cord blood plasma-derived mesenchymal stem cells and cord blood plasma. They can be considered promising new agents for promoting skin wound healing.

dEREGulated pathways: unraveling the role of epiregulin in skin, kidney, and lung fibrosis

The epidermal growth factor receptor (EGFR) signaling pathway is an evolutionary conserved mechanism to control cell behavior during tissue development and homeostasis. Deregulation of this pathway has been associated with abnormal cell behavior, including hyperproliferation, senescence, and an inflammatory cell phenotype, thereby contributing to pathologies across a variety of organs, including the kidneys, skin, and lungs. To date, there are seven distinct EGFR ligands described. Although binding of these ligands to the receptor is cell type-specific and spatio-temporally controlled with distinct affinities and kinetics, epiregulin (EREG) stands out as a long-acting EGFR ligand that emerges under pathological conditions, particularly in tissue fibrosis. Although EREG has been extensively studied in cancer, its contribution to the maladaptive remodeling of tissue is elusive. The aim of this review is to highlight the role of EREG in skin, kidney, and lung fibrosis and to discuss opportunities for therapeutic intervention.

Plasma-Activated Water Improve Wound Healing in Diabetic Rats by Influencing the Inflammatory and Remodelling Phase

Diabetic foot ulcers have an enormous impact on patients' quality of life and represent a major economic burden. The cause is delayed and incomplete wound healing due to hyperglycemia, reduced blood flow, infections, oxidative stress and chronic inflammation. Plasma-activated water (PAW) is emerging as a new therapeutic approach in wound treatment, as it has many of the advantages of cold atmospheric plasma but is easier to apply, thus allowing for widespread use. The aim of this study was to investigate the potential of PAW to improve wound healing in diabetic rats, with a focus on uncovering the underlying mechanisms. Two full-thickness wounds in control and diabetic animals were treated with PAW, and healing was monitored for 15 days at five time points. PAW improved wound healing in diabetic rats and mainly affected the inflammatory phase of wound healing. Application of PAW decreased the number of inflammatory cells, myeloperoxidase (MPO) and N-acetyl-b-D-glycosaminidase (NAG) activity, as well as the mRNA expression of proinflammatory genes in diabetic rats. Ten days after injury, PAW treatment increased collagen deposition in the diabetic animals by almost 10% without affecting collagen mRNA expression, and this is in correlation with a decrease in the Mmp-9/Timp-1 ratio. In conclusion, PAW treatment affects wound healing by reducing the inflammatory response and influencing extracellular matrix turnover, suggesting that it has great potential to accelerate the healing of diabetic wounds.

A Comparative Analysis of Cell Proliferation and Wound Closure in Cultured Gingival Epithelial Cells Using Plasma Rich in Growth Factors and Platelet-Rich Plasma Containing Leukocytes

OBJECTIVES

 Plasma rich in growth factors (PRGF) is presumed to be able to stimulate the regeneration of skin and periodontal tissue. This effect can be attributed to the fact that PRGF contains fewer leukocyte-derived interleukins in comparison to platelet-rich plasma (PRP). However, a comparison of the effects of PRGF and PRP on gingival epithelial cells has not been conducted yet. Therefore, our objective was to clarify and compare the effects of PRGF and PRP on gingival epithelial cell proliferation, wound healing, and gene expression.

MATERIALS AND METHODS

 PRGF and PRP were obtained from three donors. A complete medium containing bovine pituitary extract (BPE) and growth factors was used as a positive control (PC), while a medium without BPE was used as a negative control (NC). We evaluated the presence of platelets and leukocytes, as well as the number of leukocytes, in PRP and PRGF using the cell block method and a cell counting chamber. We assessed gingival epithelial cell proliferation with WST-1 and wound healing by using cell-free culture inserts. To examine the mRNA expression of tumor necrosis factor-α (TNF-α), which is related to cell growth inhibition, and integrin β4, which contributes to cell adhesion, we used quantitative reverse transcription polymerase chain reactions (RT-PCRs) under PRGF and PRP samples in vitro. The nonparametric data were analyzed using the Kruskal-Wallis test.

RESULTS

 Large quantities of platelets were observed in both PRGF and PRP. The leukocyte concentration in PRGF was generally lower than that in PRP. Our report indicated that cell proliferation was significantly higher in PRGF than in PRP on day 1 and 2. We found that there was no significant difference in the wound closure rate between PRGF and PRP in comparison to their respective control groups. The quantitative RT-PCR revealed insignificant differences in mRNA expression as TNF-α and integrin β4 between PRGF and PRP in comparison to the each of their respective control groups.

CONCLUSION

 Our research indicated that PRGF can promote the proliferation of gingival epithelium more than PRP, contributing to the healing of periodontal tissue. TNF-α and integrin β4 mRNA expression may not be significantly involved in wound closure within the gingival epithelium under the influence of PRGF and PRP.

Novel Strategies for Angiogenesis in Tissue Injury: Therapeutic Effects of iPSCs-Derived Exosomes

Regeneration after tissue injury is a dynamic and complex process, and angiogenesis is necessary for normal physiological activities and tissue repair. Induced pluripotent stem cells are a new approach in regenerative medicine, which provides good model for the study of difficult-to-obtain human tissues, patient-specific therapy, and tissue repair. As an innovative cell-free therapeutic strategy, the main advantages of the treatment of induced pluripotent stem cells (iPSCs)-derived exosomes are low in tumorigenicity and immunogenicity, which become an important pathway for tissue injury. This review focuses on the mechanism of the angiogenic effect of iPSCs-derived exosomes on wound repair in tissue injury and their potential therapeutic targets, with a view to providing a theoretical basis for the use of iPSCs-derived exosomes in clinical therapy.

RF pulsed plasma modified composite scaffold for enhanced anti-microbial activity and accelerated wound healing

Infected wounds present significant challenges pertaining to healing and often demand administration of strong antibiotics to patients. Also, drug resistant microbes may alter the physiology of wounds to create biofilms, frequently leading to high morbidity and mortality. In this investigation, a biodegradable, microporous composite agarose-chitosan scaffold was fabricated. Furthermore, its surface was modified with diphenyldiselenide deposition, using low pressure pulsed plasma technology. The optimized plasma parameters, viz. 5ON/15OFF (ms) of plasma pulse rate and 80 min of treatment time resulted in scaffolds having enhanced anti-bacterial activity against gram positive microbes like Staphylococcus (S.) aureus and S. epidermidis. The scaffolds were non-toxic to skin cells, as confirmed by the MTT assay. Cell proliferation through plasma treated and untreated scaffolds was assessed by culturing primary human dermal fibroblasts (HdaF) and human keratinocytes (HaCaT) and visualizing via confocal microscopy. Moreover, in-vivo rat model confirmed accelerated wound healing with plasma treated scaffold (100 % on day 14), as compared to the untreated scaffold (100 % on day 16) when compared with over-the-counter (OTC) ointment Betadine (100 % on day 12).

Applications of blood plasma derivatives for cutaneous wound healing: A mini-review of clinical studies

Skin injuries are a global healthcare problem. Chronic ulcers do not heal in a timely fashion, so it is essential to help the body with skin repair. There are some treatments that have been applied to chronic ulcers. One of these treatments is growth factor (GF) therapy. Platelet-rich plasma (PRP) and Platelet-poor plasma (PPP) are two types of plasma derivatives containing many GFs important for wound healing. Several works have reported their application in wound healing and tissue regeneration. The use of autologous PRP is now an adequate alternative in regenerative medicine. It was also demonstrated that PPP is a hemostatic agent for wounds. This review has studied the latest clinical studies, which have applied PRP and PPP to patients with chronic wounds.

Schwann cell autotransplantation for the treatment of peripheral nerve injury

Peripheral nerve injury occurs in a relatively large proportion of trauma patients, in whom it generally results in severe functional impairment and permanent disability. At present, however, there are no effective treatments available. Studies have shown that Schwann cells play an indispensable role in removing myelin debris and guiding axonal regeneration, and transplantation using autologous Schwann cells has shown good efficacy for patients with peripheral nerve injury. In recent years, Schwann cell autologous transplantation therapy has become an area of intensive research and is anticipated to provide a new strategy for the clinical treatment of peripheral nerve injury. In this article, we review the rationale for selecting Schwann cell autotransplantation therapy and the latest progress in key aspects of cell transplantation and clinical efficacy, and also summarize the future directions of research on this therapy. All of the above provide a strong basis for the further improvement and clinical promotion of this therapy.

Targeted Antibacterial Endolysin to Treat Infected Wounds on 3D Full-Thickness Skin Model: XZ.700 Efficacy

Backgrounds/Objectives: Skin wound healing is a physiological process orchestrated by epithelial and mesenchymal cells able to restore tissue continuity by re-organizing themselves and the ECM. This research study aimed to develop an optimized in vitro experimental model of full-thickness skin, to address molecular and morphological modifications occurring in the re-epithelization and wound healing process. Methods: Wound healing starting events were investigated within an experimental window of 8 days at the molecular level by gene expression and immunofluorescence of key epidermal and dermal biomarkers. To mirror the behavior of infected wounds, the established wound healing model was then colonized with S. aureus, and the efficacy of a novel antibacterial agent, XZ.700, was investigated. Viable counts (CFU/tissue), IF, and ultrastructural analysis (SEM) were performed to evaluate S. aureus colonization inside and around the wound bed in an experimental window of 3 h of colonization and 24 h of treatment. Results: Endolysin showed an efficacy in counteracting bacterial growth and invasion within the wound bed, reducing the S. aureus load compared to its placebo, thanks to its selective antimicrobial activity interfering with biofilm formation. Conclusions: The preclinical in vitro infected wound model on FT-kin showed interesting applications to assess the repair efficacy of dermo-pharmaceutical and cosmetic formulations.

Wound healing: insights into autoimmunity, ageing, and cancer ecosystems through inflammation and IL-6 modulation

Wound healing represents a complex and evolutionarily conserved process across vertebrates, encompassing a series of life-rescuing events. The healing process runs in three main phases: inflammation, proliferation, and maturation/remodelling. While acute inflammation is indispensable for cleansing the wound, removing infection, and eliminating dead tissue characterised by the prevalence of neutrophils, the proliferation phase is characterised by transition into the inflammatory cell profile, shifting towards the prevalence of macrophages. The proliferation phase involves development of granulation tissue, comprising fibroblasts, activated myofibroblasts, and inflammatory and endothelial cells. Communication among these cellular components occurs through intercellular contacts, extracellular matrix secretion, as well as paracrine production of bioactive factors and proteolytic enzymes. The proliferation phase of healing is intricately regulated by inflammation, particularly interleukin-6. Prolonged inflammation results in dysregulations during the granulation tissue formation and may lead to the development of chronic wounds or hypertrophic/keloid scars. Notably, pathological processes such as autoimmune chronic inflammation, organ fibrosis, the tumour microenvironment, and impaired repair following viral infections notably share morphological and functional similarities with granulation tissue. Consequently, wound healing emerges as a prototype for understanding these diverse pathological processes. The prospect of gaining a comprehensive understanding of wound healing holds the potential to furnish fundamental insights into modulation of the intricate dialogue between cancer cells and non-cancer cells within the cancer ecosystem. This knowledge may pave the way for innovative approaches to cancer diagnostics, disease monitoring, and anticancer therapy.

Toxicological Assessment of 2-Hydroxychalcone-Mediated Photodynamic Therapy: Comparative In Vitro and In Vivo Approaches

BACKGROUND

Photodynamic therapy (PDT) is a treatment modality that uses light to activate a photosensitizing agent, destroying target cells. The growing awareness of the necessity to reduce or eliminate the use of mammals in research has prompted the search for safer toxicity testing models aligned with the new global guidelines and compliant with the relevant regulations.

OBJECTIVE

The objective of this study was to assess the impact of PDT on alternative models to mammals, including in vitro three-dimensional (3D) cultures and in vivo, in invertebrate animals, utilizing a potent photosensitizer, 2-hydroxychalcone.

METHODS

Cytotoxicity was assessed in two cellular models: monolayer (2D) and 3D. For this purpose, spheroids of two cell lines, primary dermal fibroblasts (HDFa) and adult human epidermal cell keratinocytes (HaCat), were developed and characterized following criteria on cell viability, shape, diameter, and number of cells. The survival percentages of Caenorhabditis elegans and Galleria mellonella were evaluated at 1 and 7 days, respectively.

RESULTS

The findings indicated that all the assessed platforms are appropriate for investigating PDT toxicity. Furthermore, 2-hydroxychalcone demonstrated low toxicity in the absence of light and when mediated by PDT across a range of in vitro (2D and 3D cultures) and in vivo (invertebrate animal models, including G. mellonella and C. elegans) models.

CONCLUSION

There was a strong correlation between the in vitro and in vivo tests, with similar toxicity results, particularly in the 3D models and C. elegans, where the concentration for 50% viability was approximately 100 µg/mL.

The wound healing of deep partial-thickness burn in Bama miniature pigs is accelerated by a higher dose of hUCMSCs

BACKGROUND

Deep partial-thickness burns have a significant impact on both the physical and mental health of patients. Our previous study demonstrated human Umbilical Cord Mesenchymal stem cells (hUCMSCs) could enhance the healing of severe burns in small animal burn models, such as rats. Furthermore, our team has developed a deep partial-thickness burn model in Bama miniature pigs, which can be utilized for assessing drug efficacy in preclinical trials for wound healing. Therefore, this study further determine the optimal dosage of hUCMSCs in future clinical practice by comparing the efficacy of low-to-high doses of hUCMSCs on deep partial-thickness burn wounds in Bama miniature pigs.

MATERIALS AND METHODS

The male Bama miniature pigs (N = 8, weight: 23-28 kg and length: 71-75 cm) were used to establish deep partial-thickness burn models, which used a continuous pressure of 1 kg and contact times of 35 s by the invented electronic burn instrument at 100℃ to prepare 10 round burn wounds with diameter of 5 cm according to our previous report. And then, 0 × 10^7, 1 × 10^7, 2 × 10^7, 5 × 10^7 and 1 × 10^8 doses of hUCMSCs were respectively injected into burn wounds of their corresponding groups. After treatment for 7, 14 and 21 days, the burned wound tissues were obtained for histological evaluation, including HE staining for histopathological changes, immunohistochemistry for neutrophil (MPO+) infiltration and microvessel (CD31+) quantity, as well as Masson staining for collagen deposition. The levels of inflammatory factors TNF-α, IL-1β, IL-10 and angiogenesis factors angiopoietin-2 (Ang-2), vascular endothelial growth factor (VEGF), as well as collagen type-I/type-III of the wound tissues were quantified by ELISA.

RESULTS

All of doses hUCMSCs can significantly increase wound healing rate and shorten healing time of the deep partial-thickness burn pigs in a dose-dependent manner. Furthermore, all of doses hUCMSCs can significantly promote epithelialization and decreased inflammatory reaction of wound, including infiltration of inflammatory cells and levels inflammatory factors. Meanwhile, the amounts of microvessel were increased in all of doses hUCMSCs group than those in the burn group. Furthermore, the collagen structure was disordered and partially necrotized, and ratios of collagen type-I and type-III were significantly decreased in burn group (4:1 in normal skin tissue), and those of all hUCMSCs groups were significantly improved in a dose-dependent manner. In a word, 1 × 10^8 dose of hUCMSCs could regenerate the deep partial-thickness burn wounds most efficaciously compared to other dosages groups and the burn group.

CONCLUSION

This regenerative cell therapy study using hUCMSCs demonstrates the best efficacy toward a high dose, that is dose of 1 × 10^8 of hUCMSCs was used as a reference therapeutic dose for treating 20 cm2 deep partial-thickness burns wound in future clinical practice.

Modulatory Effects of 830 nm on Diabetic Wounded Fibroblast Cells: An In Vitro Study on Inflammatory Cytokines

Background:After skin damage, a complicated set of processes occur for epidermal and dermal wound healing. This process is hindered under diabetic conditions, resulting in nonhealing diabetic ulcers. In diabetes there is an increase in inflammation and proinflammatory cytokines. Modulating cells using photobiomodulation (PBM) may have an effect on inflammation and cell viability, which are crucial for the healing of wounds. Objective: This study explored the impact of PBM in the near-infrared spectrum (830 nm; 5 J/cm2) on inflammation in diabetic wound healing. Materials and Methods: Five cell models, namely normal, wounded, diabetic, diabetic wounded, and wounded with d-galactose were used. Cell morphology and migration rate were assessed, while cellular response measures included viability (Trypan blue and adenosine triphosphate), apoptosis (annexin-V/PI), proinflammatory cytokines interleukin-6, tumor necrosis factor-alpha (TNF-α), and cyclooxygenase-2, nuclear translocation of nuclear factor kappa B (NF-κB), and gene expression of advanced glycation end product receptor (AGER). Results: PBM resulted in increased levels of TNF-α, supported by activation of NF-κB. PBM stimulated translocation of NF-κB and upregulation of AGER. Conclusions: PBM modulates diabetic wound healing in vitro at 830 nm through stimulated NF-κB signaling activated by TNF-α.

Boron in wound healing: a comprehensive investigation of its diverse mechanisms

Chronic wounds present a significant clinical challenge due to their prolonged healing time and susceptibility to infection. Boron, a trace element with diverse biological functions, has emerged as a promising therapeutic agent in wound healing. This review article comprehensively investigates the mechanisms underlying the beneficial effects of boron compounds in wound healing. Boron exerts its healing properties through multiple pathways, including anti-inflammatory, antimicrobial, antioxidant, and pro-proliferative effects. Inflammation is a crucial component of the wound-healing process, and boron has been shown to modulate inflammatory responses by inhibiting pro-inflammatory cytokines and promoting the resolution of inflammation. Furthermore, boron exhibits antimicrobial activity against a wide range of pathogens commonly associated with chronic wounds, thereby reducing the risk of infection and promoting wound closure. The antioxidant properties of boron help protect cells from oxidative stress, a common feature of chronic wounds that can impair healing. Additionally, boron stimulates cell proliferation and migration, as well as essential tissue regeneration and wound closure processes. Overall, this review highlights the potential of boron as a novel therapeutic approach for treating chronic wounds, offering insights into its diverse mechanisms of action and clinical implications.

Efficacy and safety of allogeneic platelet-rich plasma in chronic wound treatment: a meta-analysis of randomized controlled trials

Allogeneic platelet-rich plasma (al-PRP) is gaining attention in clinical practice for treating chronic refractory wounds, though research results remain controversial. To assess the clinical efficacy of al-PRP for chronic refractory wounds. Databases including PubMed, Cochrane Library, Embase, CNKI, SinoMed, VIP, and WFPD were searched for randomized controlled trials comparing al-PRP with conventional treatments up to October 2023. Two researchers independently screened studies, extracted data, and assessed quality. Statistical analysis was conducted using RevMan 5.4, and potential publication bias was assessed and corrected using funnel plots and Egger's test. Twelve studies with 717 cases were included. Meta-analysis showed al-PRP significantly improved outcomes compared to non-al-PRP treatments: increased healing rate (RR 2.72, 95% CI 1.77-4.19, p < 0.00001), shortened healing time (SMD - 1.03, 95% CI -1.31 to -0.75, p < 0.00001), improved efficacy rate (RR 1.19, 95% CI 1.10-1.28, p < 0.00001), increased wound shrinkage (MD 35.65%, 95% CI 21.65-49.64, p < 0.00001), and reduced hospital stays (MD -2.62, 95% CI -4.35 to -0.90, p = 0.003). Al-PRP is a feasible, effective, and safe biological therapy for chronic refractory wounds.Trial registration: PROSPERO Identifier CRD42022374920.

Radiofrequency Currents Modulate Inflammatory Processes in Keratinocytes

Keratinocytes play an essential role in the inflammatory phase of wound regeneration. In addition to migrating and proliferating for tissue regeneration, they produce a large amount of cytokines that modulate the inflammatory process. Previous studies have shown that subthermal treatment with radiofrequency (RF) currents used in capacitive resistive electric transfer (CRET) therapy promotes the proliferation of HaCat keratinocytes and modulates their cytokine production. Although physical therapies have been shown to have anti-inflammatory effects in a variety of experimental models and in patients, knowledge of the biological basis of these effects is still limited. The aim of this study was to investigate the effect of CRET on keratinocyte proliferation, cytokine production (IL-8, MCP-1, RANTES, IL-6, IL-11), TNF-α secretion, and the expression of MMP9, MMP1, NF-κB, ERK1/2, and EGFR. Human keratinocytes (HaCat) were treated with an intermittent 448 kHz electric current (CRET signal) in subthermal conditions and for different periods of time. Cell proliferation was analyzed by XTT assay, cytokine and TNF-α production by ELISA, NF-κB expression and activation by immunofluorescence, and MMP9, MMP1, ERK1/2, and EGF receptor expression and activation by immunoblot. Compared to a control, CRET increases keratinocyte proliferation, increases the transient release of MCP-1, TNF-α, and IL-6 while decreasing IL-8. In addition, it modifies the expression of MMPs and activates EGFR, NF-κB, and ERK1/2 proteins. Our results indicate that CRET reasonably modifies cytokine production through the EGF receptor and the ERK1/2/NF-κB pathway, ultimately modulating the inflammatory response of human keratinocytes.

Inflammation-induced subcutaneous neovascularization for the long-term survival of encapsulated islets without immunosuppression

Cellular therapies for type-1 diabetes can leverage cell encapsulation to dispense with immunosuppression. However, encapsulated islet cells do not survive long, particularly when implanted in poorly vascularized subcutaneous sites. Here we show that the induction of neovascularization via temporary controlled inflammation through the implantation of a nylon catheter can be used to create a subcutaneous cavity that supports the transplantation and optimal function of a geometrically matching islet-encapsulation device consisting of a twisted nylon surgical thread coated with an islet-seeded alginate hydrogel. The neovascularized cavity led to the sustained reversal of diabetes, as we show in immunocompetent syngeneic, allogeneic and xenogeneic mouse models of diabetes, owing to increased oxygenation, physiological glucose responsiveness and islet survival, as indicated by a computational model of mass transport. The cavity also allowed for the in situ replacement of impaired devices, with prompt return to normoglycemia. Controlled inflammation-induced neovascularization is a scalable approach, as we show with a minipig model, and may facilitate the clinical translation of immunosuppression-free subcutaneous islet transplantation.

Reflecting the human lip in vitro: Cleft lip skin and mucosa keratinocytes keep their identities

OBJECTIVES

Cell models have shown great promise as tools for research, potentially providing intriguing alternatives to animal models. However, the original tissue characteristics must be maintained in culture, a fact that is often assumed, but seldom assessed. We aimed to follow the retention of the original tissue identities of cleft lip-derived skin and mucosa keratinocytes in vitro.

METHODS

Cleft lip-derived keratinocytes were isolated from discarded tissue along the cleft margins during cheiloplasty. Cell identities were assessed by immunohistochemistry and quantitative real-time PCR for tissue-specific markers and compared with native lip tissue. Moreover, keratinocytes were regularly analyzed for the retention of the original tissue characteristics by the aforementioned methods as well as by differentiation assays.

RESULTS

The various anatomical zones of the human lip could be distinguished using a panel of differentiation and functional-based markers. Using these markers, retention of the original tissue identities could be followed and confirmed in the corresponding primary keratinocytes in culture.

CONCLUSIONS

Our findings promote patient-derived cells retaining their original identities as astonishing and clinically relevant in vitro tools. Such cells allow a better molecular understanding of various lip-associated pathologies as well as their modeling in vitro, including but not restricted to orofacial clefts.

Redox-Responsive Hydrogels Loaded with an Antibacterial Peptide as Controlled Drug Delivery for Healing Infectious Wounds

Infectious wounds occur when harmful microorganisms such as bacteria or viruses invade a wound site. Its problems associated include delayed healing, increased pain, swelling, and the potential for systemic infections. Therefore, developing new wound dressing materials with antibacterial effects is crucial for improving the healing process. Here a redox-degradable hydrogel loaded with an antibacterial peptide (vancomycin) in a straightforward gram-scale synthesis, is developed. The hydrogel structure consists of a disulfide bond-containing hyperbranched polyglycerol (SS-hPG) that is cross-linked by 4-arm polyethylene glycol-thiol (4-arm PEG-SH). The polymerization mechanism and full characterization of SS-hPG are described as this synthesis is reported for the first time. Rheology is used to ascertain the hydrogel's mechanical characteristics, such as stiffness, and self-healing, determining these properties for different ratios and concentrations of both gel components. The incorporation of disulfide bonds in the hydrogel is proved by conducting degradation experiments in reductive environments. Fluorescein isothiocyanate-albumin (FITC-BSA) and vancomycin both are loaded into the gel, and the guest release kinetics is assessed for both slow and on-demand releases. Finally, the in vitro and in vivo experiments prove that the vancomycin-loaded hydrogel acts as an antibacterial barrier for wound dressing and accelerates the healing of infectious wounds in a mouse model.

Natural products for the treatment of hypertrophic scars: Preclinical and clinical studies

Hypertrophic scarring (HS) is a complication of wound healing that causes physiological and psychological distress in patients. However, the possible mechanism underlying HS is not fully understood, and there is no gold standard for its treatment. Natural products are more effective, economical, convenient, and safe than existing drugs, and they have a wide application prospect. However, there is a lack of literature on this topic, so we reviewed in vivo, in vitro, and clinical studies and screened natural products showing beneficial effects on HS that can become potential therapeutic agents for HS to fill in the gaps in the field. In addition, we discussed the drug delivery systems related to these natural products and their mechanisms in the treatment of HS. Generally speaking, natural products inhibit inflammation, myofibroblast activation, angiogenesis, and collagen accumulation by targeting interleukins, tumor necrosis factor-α, vascular endothelial growth factors, platelet-derived growth factors, and matrix metalloproteinases, so as to play an anti-HS effects of natural products are attributed to their anti-inflammatory, anti-proliferative, anti-angiogenesis, and pro-apoptotic (enhancing apoptosis and autophagy) roles, thus treating HS. We also screened the potential therapeutic targets of these natural compounds for HS through network pharmacology and constructed a protein-protein interaction (PPI) network, which may provide clues for the pharmacological mechanism of natural products in treating this disease and the development and application of drugs.

Low-temperature pulverization-specific Sargassum horneri extract accelerates wound healing and attenuates inflammation in a mouse burn model

Burn injuries, affecting local skin disruption as well as inducing systemic inflammatory responses, are presented as a global public health problem. To enhance the effects of burn wound healing, treatment must simultaneously regulate both re-epithelialization and hyperinflammation. Extracts of Sargassum horneri (S. horneri) have shown a potential to enhance skin wound healing through antioxidative properties, immune enhancement, and modulation of inflammatory responses. However, despite its promising application for burn wound healing, specific investigation into S. horneri-derived compounds for enhancing wound healing has not yet been conducted. In this research, we investigated the burn wound-healing effect of the low-temperature pulverization-specific S. horneri extract (LPSHE), which could not be detected using the room-temperature grinding method. In a mouse burn model with third-degree burn injuries, LPSHE accelerated re-epithelialization by promoting the increase in F-actin formation and reduced burn-induced ROS levels. Additionally, LPSHE significantly regulated hyperinflammation by reducing pro-inflammatory cytokines. Further investigation into molecular mechanisms using HaCaT keratinocytes also demonstrated beneficial effects on burn wound healing. Taken together, our findings suggested that LPSHE is a promising therapeutic candidate for enhancing burn wound healing. Furthermore, this research underscored the importance of low-temperature pulverization in discovering novel natural compounds from marine organisms.

Developmental prospects of carrageenan-based wound dressing films: Unveiling techno-functional properties and freeze-drying technology for the development of absorbent films - A review

This review explores the intricate wound healing process, emphasizing the critical role of dressing material selection, particularly for chronic wounds with high exudate levels. The aim is to tailor biodegradable dressings for comprehensive healing, focusing on maximizing moisture retention, a vital element for adequate recovery. Researchers are designing advanced wound dressings that enhance techno-functional and bioactive properties, minimizing healing time and ensuring cost-effective care. The study delves into wound dressing materials, highlighting carrageenan biocomposites superior attributes and potential in advancing wound care. Carrageenan's versatility in various biomedical applications demonstrates its potential for tissue repair, bone regeneration, and drug delivery. Ongoing research explores synergistic effects by combining carrageenan with other novel materials, aiming for complete biocompatibility. As innovative solutions emerge, carrageenan-based wound-healing medical devices are poised for global accessibility, addressing challenges associated with the complex wound-healing process. The exceptional physico-mechanical properties of carrageenan make it well-suited for highly exudating wounds, offering a promising avenue to revolutionize wound care through freeze-drying techniques. This thorough approach to evaluating the wound healing effectiveness of carrageenan-based films, particularly emphasizing the development potential of lyophilized films, has the potential to significantly improve the quality of life for patients receiving wound healing treatments.

Exploring the role of dermal sheath cells in wound healing and fibrosis

Wound healing is a complex, dynamic process involving the coordinated interaction of diverse cell types, growth factors, cytokines, and extracellular matrix components. Despite emerging evidence highlighting their importance, dermal sheath cells remain a largely overlooked aspect of wound healing research. This review explores the multifunctional roles of dermal sheath cells in various phases of wound healing, including modulating inflammation, aiding in proliferation, and contributing to extracellular matrix remodelling. Special attention is devoted to the paracrine effects of dermal sheath cells and their role in fibrosis, highlighting their potential in improving healing outcomes, especially in differentiating between hairy and non-hairy skin sites. By drawing connections between dermal sheath cells activity and wound healing outcomes, this work proposes new insights into the mechanisms of tissue regeneration and repair, marking a step forward in our understanding of wound healing processes.

Sequential management of burn wound healing stages through biointelligence-inspired platelet extracellular vesicle-encapsulated photodynamic diferuloylmethane

The process of wound healing is a complex, multi-phase phenomenon crucial for optimal tissue regeneration. Traditional drug delivery systems often target specific phases of wound repair, neglecting the dynamic interplay among the stages. This limitation highlights the need for comprehensive delivery systems that cater to the holistic needs of wound healing, enhancing tissue regeneration efficiency. Herein, we explored the utility of platelet-derived extracellular vesicles (pEVs) as carriers for the phototherapeutic diferuloylmethane (DIF), resulting in a formulation termed DIF@pEVs, which is designed to sequentially address the distinct phases of wound healing. Initially, upon exposure to light, administered DIF@pEVs generate photodynamic therapy-derived reactive oxygen species during the early inflammatory phase. This generation of ROS aims to modulate the inflammatory response, induce the protective mechanisms of heat shock proteins, and kickstart the tissue regeneration process. Following this initial phase, the remaining DIF and pEVs persist in promoting tissue repair and regeneration. Ultimately, it reduces inflammation, speeds up the healing process, and promotes vascular and follicular formation in a model of burn wound skin damage, thereby supporting skin regeneration. The deployment of DIF@pEVs represents an advancement in regenerative medicine, providing a precise, versatile approach to fostering regeneration across a wide range of clinical scenarios.

Novel Factors Regulating Proliferation, Migration, and Differentiation of Fibroblasts, Keratinocytes, and Vascular Smooth Muscle Cells during Wound Healing

Chronic diabetic foot ulcers (DFUs) are a significant complication of diabetes mellitus, often leading to amputation, increased morbidity, and a substantial financial burden. Even with the advancements in the treatment of DFU, the risk of amputation still exists, and this occurs due to the presence of gangrene and osteomyelitis. Nonhealing in a chronic DFU is due to decreased angiogenesis, granulation tissue formation, and extracellular matrix remodeling in the presence of persistent inflammation. During wound healing, the proliferation and migration of fibroblasts, smooth muscle cells, and keratinocytes play a critical role in extracellular matrix (ECM) remodeling, angiogenesis, and epithelialization. The molecular factors regulating the migration, proliferation, and differentiation of these cells are scarcely discussed in the literature. The literature review identifies the key factors influencing the proliferation, migration, and differentiation of fibroblasts, keratinocytes, and vascular smooth muscle cells (VSMCs), which are critical in wound healing. This is followed by a discussion on the various novel factors regulating the migration, proliferation, and differentiation of these cells but not in the context of wound healing; however, they may play a role. Using a network analysis, we examined the interactions between various factors, and the findings suggest that the novel factors identified may play a significant role in promoting angiogenesis, granulation tissue formation, and extracellular matrix remodeling during wound healing or DFU healing. However, these interactions warrant further investigation to establish their role alone or synergistically.

Polyphosphate Nanoparticles: Balancing Energy Requirements in Tissue Regeneration Processes

Nanoparticles of a particular, evolutionarily old inorganic polymer found across the biological kingdoms have attracted increasing interest in recent years not only because of their crucial role in metabolism but also their potential medical applicability: it is inorganic polyphosphate (polyP). This ubiquitous linear polymer is composed of 10-1000 phosphate residues linked by high-energy anhydride bonds. PolyP causes induction of gene activity, provides phosphate for bone mineralization, and serves as an energy supplier through enzymatic cleavage of its acid anhydride bonds and subsequent ATP formation. The biomedical breakthrough of polyP came with the development of a successful fabrication process, in depot form, as Ca- or Mg-polyP nanoparticles, or as the directly effective polymer, as soluble Na-polyP, for regenerative repair and healing processes, especially in tissue areas with insufficient blood supply. Physiologically, the platelets are the main vehicles for polyP nanoparticles in the circulating blood. To be biomedically active, these particles undergo coacervation. This review provides an overview of the properties of polyP and polyP nanoparticles for applications in the regeneration and repair of bone, cartilage, and skin. In addition to studies on animal models, the first successful proof-of-concept studies on humans for the healing of chronic wounds are outlined.

Nanosized Complexes of the Proteolytic Enzyme Serratiopeptidase with Cationic Block Copolymer Micelles Enhance the Proliferation and Migration of Human Cells

In this study, we describe the preparation of the cationic block copolymer nanocarriers of the proteolytic enzyme serratiopeptidase (SER). Firstly, an amphiphilic poly(2-(dimethylamino)ethyl methacrylate)-b-poly(ε-caprolactone)-b-poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA9-b-PCL35-b-PDMAEMA9) triblock copolymer was synthesized by reversible addition-fragmentation chain-transfer (RAFT) polymerization. Then, cationic micellar nanocarriers consisting of a PCL hydrophobic core and a PDMAEMA hydrophilic shell were formed by the solvent evaporation method. SER was loaded into the polymeric micelles by electrostatic interaction between the positively charged micellar shell and the negatively charged enzyme molecules. The particle size, zeta potential, and colloid stability of complexes as a function of SER concentration were investigated by dynamic and electrophoretic light scattering. It was found that SER retained its proteolytic activity after immobilization in polymeric carriers. Moreover, the complexes have a concentration-dependent enhancing effect on the proliferation and migration of human keratinocyte HaCaT and gingival fibroblast HGF cells.

Engineered exosomes as a prospective therapy for diabetic foot ulcers

Diabetic foot ulcer (DFU), characterized by high recurrence rate, amputations and mortality, poses a significant challenge in diabetes management. The complex pathology involves dysregulated glucose homeostasis leading to systemic and local microenvironmental complications, including peripheral neuropathy, micro- and macro-angiopathy, recurrent infection, persistent inflammation and dysregulated re-epithelialization. Novel approaches to accelerate DFU healing are actively pursued, with a focus on utilizing exosomes. Exosomes are natural nanovesicles mediating cellular communication and containing diverse functional molecular cargos, including DNA, mRNA, microRNA (miRNA), lncRNA, proteins, lipids and metabolites. While some exosomes show promise in modulating cellular function and promoting ulcer healing, their efficacy is limited by low yield, impurities, low loading content and inadequate targeting. Engineering exosomes to enhance their curative activity represents a potentially more efficient approach for DFUs. This could facilitate focused repair and regeneration of nerves, blood vessels and soft tissue after ulcer development. This review provides an overview of DFU pathogenesis, strategies for exosome engineering and the targeted therapeutic application of engineered exosomes in addressing critical pathological changes associated with DFUs.

Design Strategy of Microneedle Systems for Skin Wound Healing: Based on the Structure of Tips and Therapeutic Methodologies

The skin, being the largest organ of the human body, is susceptible to damage resulting in wounds that are vulnerable to pathogenic attacks and fail to provide effective protection for internal tissues. Therefore, it is crucial to expedite wound healing. In recent years, microneedles have garnered significant attention as an innovative drug delivery system owing to their noninvasive and painless administration, simplified application process, precise control over drug release, and versatile loading capabilities. Consequently, they hold immense potential for the treatment of skin wound. This review presents a comprehensive design strategy for the microneedle system in promoting skin wound healing. First, the process of skin wound healing and the characteristics of specific wounds are elucidated. The design strategies for microneedles are subsequently presented and classified based on their structural and therapeutic methodologies. Finally, a succinct recapitulation of the previously discussed points and a prospective analysis are provided.

Polymer-Based Wound Dressings Loaded with Essential Oil for the Treatment of Wounds: A Review

Wound healing can result in complex problems, and discovering an effective method to improve the healing process is essential. Polymeric biomaterials have structures similar to those identified in the extracellular matrix of the tissue to be regenerated and also avoid chronic inflammation, and immunological reactions. To obtain smart and effective dressings, bioactive agents, such as essential oils, are also used to promote a wide range of biological properties, which can accelerate the healing process. Therefore, we intend to explore advances in the potential for applying hybrid materials in wound healing. For this, fifty scientific articles dated from 2010 to 2023 were investigated using the Web of Science, Scopus, Science Direct, and PubMed databases. The principles of the healing process, use of polymers, type and properties of essential oils and processing techniques, and characteristics of dressings were identified. Thus, the plants Syzygium romanticum or Eugenia caryophyllata, Origanum vulgare, and Cinnamomum zeylanicum present prospects for application in clinical trials due to their proven effects on wound healing and reducing the incidence of inflammatory cells in the site of injury. The antimicrobial effect of essential oils is mainly due to polyphenols and terpenes such as eugenol, cinnamaldehyde, carvacrol, and thymol.

Skin rejuvenation through topical application of indocyanine green with diffractive optical element mode of 785 nm picosecond laser in Asian females

BACKGROUND

Indocyanine green (ICG) exhibits robust absorption near 800 nm.

AIMS

To examine the clinical effects of combining ICG with a 785 nm picosecond laser for treating photo-aged skin.

PATIENT/METHODS

A 785 nm 600 picosecond laser was used on the facial area of 16 female patients with Fitzpatrick skin type III and IV (mean age: 58.44 ± 5.24 years) after applying 0.0125% ICG cream. A total of 3000 shots were administered in diffractive optical element mode at a pulse energy of 200 mJ and frequency of 10 Hz. Hyperpigmented lesions were treated using the Zoom handpiece set at a spot size of 3-4 mm, pulse energy of 60-120 mJ, and frequency of 3-7 Hz. Patients underwent five sessions of treatment at intervals of 1-2 weeks. Wrinkles, pores and pigmented lesions were assessed at the initial assessment and 4 weeks after the final treatment using the Modified Fitzpatrick Wrinkle Scale and 10-point visual analog scale, respectively. Skin biopsy of the postauricular area was performed on two consenting patients.

RESULTS

Significant improvements in wrinkles (p = 0.02), pores (p = 0.034), and hyperpigmentation (p = 0.036) were observed, along with increased patient subjective improvement. Adverse effects were transient and well-tolerated. Hematoxylin and eosin and Masson's trichrome staining revealed increased and thickened dermal collagen fibers. Immunohistochemical staining revealed increased expression of collagen I and III throughout the papillary and upper reticular dermis, along with diffuse increase of STRO-1 in the dermis.

CONCLUSIONS

The combined application of a 785 nm picosecond laser and ICG yielded promising clinical outcomes for treating photo-aged skin in Asian patients with Fitzpatrick skin type III and IV.

Aloesin-loaded chitosan/cellulose-based scaffold promotes skin tissue regeneration

Skin wound healing and regeneration is very challenging across the world as simple or acute wounds can be transformed into chronic wounds or ulcers due to foreign body invasion, or diseases like diabetes or cancer. The study was designed to develop a novel bioactive scaffold, by loading aloesin to chitosan-coated cellulose scaffold, to cure full-thickness skin wounds. The physiochemical characterization of the scaffold was carried out using scanning electron microscopy (SEM) facilitated by energy-dispersive spectrophotometer (EDS), atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR). The results indicated the successful coating of chitosan and aloesin on cellulose without any physical damage. The drug release kinetics confirmed the sustained release of aloesin by showing a cumulative release of up to 88 % over 24 h. The biocompatibility of the aloesin-loaded chitosan/cellulose (AlCsCFp) scaffold was evaluated by the WST-8 assay that confirmed the significantly increased adherence and proliferation of fibroblasts on the AlCsCFp scaffold. The in vivo wound healing study showed that both 0.05 % and 0.025 % AlCsCFp scaffolds have significantly higher wound closure rates (i.e. 88.2 % and 95.6 % approximately) as compared to other groups. This showed that novel composite scaffold has a wound healing ability. Furthermore, histological and gene expression analysis demonstrated that the scaffold also induced cell migration, angiogenesis, re-epithelialization, collagen deposition, and tissue granulation formation. Thus, it is concluded that the aloesin-loaded chitosan/cellulose-based scaffold has great therapeutic potential for being used in wound healing applications in the clinical setting in the future.

Biomaterials for extrusion-based bioprinting and biomedical applications

Amongst the range of bioprinting technologies currently available, bioprinting by material extrusion is gaining increasing popularity due to accessibility, low cost, and the absence of energy sources, such as lasers, which may significantly damage the cells. New applications of extrusion-based bioprinting are systematically emerging in the biomedical field in relation to tissue and organ fabrication. Extrusion-based bioprinting presents a series of specific challenges in relation to achievable resolutions, accuracy and speed. Resolution and accuracy in particular are of paramount importance for the realization of microstructures (for example, vascularization) within tissues and organs. Another major theme of research is cell survival and functional preservation, as extruded bioinks have cells subjected to considerable shear stresses as they travel through the extrusion apparatus. Here, an overview of the main available extrusion-based printing technologies and related families of bioprinting materials (bioinks) is provided. The main challenges related to achieving resolution and accuracy whilst assuring cell viability and function are discussed in relation to specific application contexts in the field of tissue and organ fabrication.

Polymeric scaffold integrated with nanovesicle-entrapped curcuminoids for enhanced therapeutic efficacy

Aim: Polymeric scaffolds were developed fortified with nanovesicle-encapsulated individual curcumin (CUR) and tetrahydrocurcumin (THC) for improved therapeutic efficacy due to their low stability and efficacy in native form. Method: Nanovesicle-encapsulated individual CUR and THC were fabricated using thin-film hydration techniques and characterized. Results & conclusion: CUR/THC in native and vesicle-encapsulated form demonstrated diminished LPS-instigate nitric oxide (NO) levels in macrophage cells in a concentration-dependent demeanor. However, vesicle-encapsulated CUR/THC inhibited NO production at lower concentrations, compared with the native CUR/THC form. Furthermore, the scaffold fortified with vesicle-encapsulated CUR/THC demonstrated improved physical properties with excellent antioxidant, biocompatibility, and human keratinocyte cell proliferation ability. The results recommended that nanovesicle-encapsulated THC can be retained as a potential substitute for CUR with improved therapeutic efficacy.

LncRNA MALAT1 in Keratinocyte function: A review of recent advances

Keratinocytes, the principal epidermal cells, play a vital role in maintaining the structural integrity and functionality of the skin. Beyond their protective role, keratinocytes are key contributors to the process of wound healing, as they migrate to injury sites, proliferate, and generate new layers of epidermis, facilitating tissue repair and remodeling. Moreover, keratinocytes actively participate in the skin's immune responses, expressing pattern recognition receptors (PRRs) to detect microbial components and interact with immune cells to influence adaptive immunity. Keratinocytes express a diverse repertoire of signaling pathways, transcription factors, and epigenetic regulators to regulate their growth, differentiation, and response to environmental cues. Among these regulatory elements, long non-coding RNAs (lncRNAs) have emerged as essential players in keratinocyte biology. LncRNAs, including MALAT1, play diverse roles in gene regulation and cellular processes, influencing keratinocyte proliferation, differentiation, migration, and response to environmental stimuli. Dysregulation of specific lncRNAs such as MALAT1 can disrupt keratinocyte homeostasis, leading to impaired differentiation, compromised barrier integrity, and contributing to the pathogenesis of various skin disorders. Understanding the intricate interplay between lncRNAs and keratinocytes offers promising insights into the molecular underpinnings of skin health and disease, with potential implications for targeted therapies and advancements in dermatological research. Hence, our objective is to provide a comprehensive summary of the available knowledge concerning keratinocytes and their intricate relationship with MALAT1.