Skin Wound Healing Process Research Articles

The impact of sex hormones on genital wound healing in mice: a comparative study

The effects estrogen and testosterone have on penile wound healing are still uncertain. This study evaluated the effects of these hormones on the wound healing process of penile and non-penile skin in wild-type (Mus musculusspecies) 4-5-week-old mice. Seventy wild-type Mus musculusspecies were randomly assigned to four groupscontrol (n=17), 1-week post-operative topical estrogen (n=18), 1-week pre-operative testosterone (n=17), and immediate post-operative testosterone (n=18). Incisions were made on the ventrum of the penis and dorsal neck skin. On post-operative day 3, 7, and 14, incision sites were harvested. Evaluation was performed grossly for postsurgical penile edema and histologically for inflammatory cell concentration, presence of fibrinopurulent materials and distribution of collagen-fibroblastic cells. Each treatment group was compared at the three post-operative time points using the Fisher-Freeman--Halton exact test. CD34 and androgen receptor immunohistostaining was performed for between-group differences to assess microvascular density or vasodilatation and androgen receptor upregulation. In this study, the experiment noted significant penile edema on post-operative day 7 in the testosterone groups, whereas less edema in the estrogen group (P=0.010; Figure). On histologic evaluation of the penile wounds, a significantly increased inflammatory cell concentration was noted for both pre-operative and post-operative testosterone groups on post-operative day 14 (P=0.023). The estrogen group revealed significantly increased fibrinopurulent material on the 3rd and 7th post-operative days (P=0.045 and P=0.005, respectively). No significant between-group differences in the collagen-fibroblastic distribution were noted over the three-time phases. On histologic evaluation of the skin wounds, no significant differences were noted between the groups for inflammatory cell concentration and presence of fibrinopurulent materials. However, compared with the testosterone treatment groups, a significant higher collagen-fibroblast distribution was noted in the estrogen groups on post-operative day 3 and 14 (P=0.001 and P=0.044,respectively). Sex hormones, when given peri-operatively, may affect the wound healing process in mice. Testosterone appears to stimulate a prolonged inflammatory effect on penile wounds. Conversely, estrogen induces a fibrinopurulent congregation early in the penile wound healing process. For general skin healing, estrogen induces earlier collagen and fibroblast distribution, whereas testosterone has a delayed effect. The findings of this study should be further investigated in larger animal model with longer follow-up period.

Anti-inflammatory activity of Schrebera Swietenioides Roxb. in cream formulation on CD68 expression in mice skin wound

Aim: The purpose of this study was to determine the potential of Schrebera Swietenioides alcohol leaf extract in cream composition in the expression of immunoglobulin CD68 (macrophage) during the wound healing process in the inflammatory stage of mice skin.
 Materials and Methods: Amount of 12 two-months-old male mice were used between 30 and 40 g. To surgical procedures, wound skin incision was performed 2.0 cm in length until subcutaneous on the paravertebral of each animal. The treatment was carried under locally anesthetized with procaine cream. The mice were allotted into four groups of each, entire surface of each group wound covered by base cream control, sulfadiazine 0.1% cream, alcoholic leaves extract of Schrebera Swietenioides cream 10% and, 15%, respectively. All experiments were performed twice a day for 3 days. The wound healing was assayed in stained histological sections in immunohistochemical of the wounds. CD68 expression was investigated under a microscope.
 Amount of 12-month-old male mice between 30 and 40 g was used. For surgical procedures, a 2.0 cm skin lesion was also performed under the skin on the vertebrae surrounding each animal. Treatment was performed under local anesthetic with procaine cream. Rats were assigned to four groups each, the entire surface of each group of lesions covered by control cream, 0.1% sulfadiazine cream, alcohol leaf from Schrebera Swietenioides cream respectively at 10% and at 15%. All tests were performed twice a day for 3 days. The lesions were analyzed in sections of tissue with staining of wound immunochemistry. The expression of CD68 was studied under a microscope.
 Results: The results showed that the cream from the 10% and 15% alcoholic leaves extract of Schrebera Swietenioides revealed moderate immune reaction to CD68 on wound healing.
 Conclusion: We concluded that the alcoholic leaves extract cream of Schrebera Swietenioides possesses anti-inflammatory activity in wound healing process of mice skin.

TNF Receptor-Associated Factor 5 Limits Function of Plasmacytoid Dendritic Cells by Controlling IFN Regulatory Factor 5 Expression.

The physiological functions of TNF receptor-associated factor 5 (TRAF5) in the skin inflammation and wound healing process are not well characterized. We found that Traf5 -/- mice exhibited an accelerated skin wound healing as compared with wild-type counterparts. The augmented wound closure in Traf5 -/- mice was associated with a massive accumulation of plasmacytoid dendritic cells (pDCs) into skin wounds and an enhanced expression of genes related to wound repair at skin sites. In accordance with this result, adoptive transfer of Traf5 -/- pDCs, but not wild-type pDCs, into the injured skin area in wild-type recipient mice significantly promoted skin wound healing. The expression of skin-tropic chemokine receptor CXCR3 was significantly upregulated in Traf5-/- pDCs, and treatment with a CXCR3 inhibitor cancelled the promoted wound healing in Traf5-/- mice, suggesting a pivotal role of CXCR3 in pDC-dependent wound healing. Traf5 -/- pDCs displayed significantly higher expression of IFN regulatory factor 5 (IRF5), which correlated with greater induction of proinflammatory cytokine genes and CXCR3 protein after stimulation with TLR ligands. Consistently, transduction of exogeneous TRAF5 in Traf5-/- pDCs normalized the levels of abnormally elevated proinflammatory molecules, including IRF5 and CXCR3. Furthermore, knockdown of IRF5 also rescued the abnormal phenotypes of Traf5-/- pDCs. Therefore, the higher expression and induction of IRF5 in Traf5-/- pDCs causes proinflammatory and skin-tropic characteristics of the pDCs, which may accelerate skin wound healing responses. Collectively, our results uncover a novel role of TRAF5 in skin wound healing that is mediated by IRF5-dependent function of pDCs.

648 Adipose-derived stem cells in wound healing: comparison with fibroblasts and keratinocytes interaction

Adipose-derived stem cells (ADSCs) are a particular subset of mesenchymal stem cells present in the stromal-vascular fraction of the adipose tissue. These cells are considered very attractive for their relative abundance and accessibility in the human body. Keratinocytes and fibroblasts cells play important roles in the skin-wound healing process and are the cell types activated by trauma. The aim of our study was focused to evaluate ADSCs ability to build a dermal matrix to be potentially used as a dermal substitute in the field of wound healing. ADSCs were defined as Cluster Differentiation (CD) markers CD90, CD73 and CD105 positive cells and were capable of chondrogenic, osteoblastic and adipogenic differentiation using established protocols. We evaluated several ADSCs abilities in comparison with fibroblasts in order to secrete crucial components of the extracellular matrix such as collagen I and fibronectin. Moreover the culture medium conditioned by ADSCs enhanced the rate of wound closure of fibroblasts and keratinocytes on an in vitro skin wound healing model. Ki67 immunostaining evaluated keratinocyte migrating capacity and colonization on this ADSC-induced matrix demonstrating its ability to promote re-epithelization. Furthermore in the angiogenic 3D assay on Matrigel, ADSCs grown in EGM-2 medium started to form microvessels within 24 hours. This study suggests that ADSCs support vascular network formation in vitro and demonstrates that the ADSCs trophic activity may play an important role in skin wound healing by affecting keratinocytes migration and dermal fibroblasts contribution to generate extracellular matrix.

Ação do gel Anacardium Occidentale L. associado ao ultrassom terapêutico no processo de cicatrização em camundongos

INTRODUÇÃO: Os recursos fisioterapêuticos influenciam positivamente no processo de cicatrização, acelerando as diferentes fases e reduzindo o tempo de lesão através da aplicação de recursos eletrofísicos, tais como ultrassom terapêutico (UST). A interação entre o UST e os tecidos biológicos, é capaz de gerar alterações celulares, por efeitos mecânicos, garantindo resultados satisfatórios. Estudos à base dos extratos vegetais vêm sendo realizados visando comprovar terapias alternativas efetivas capazes de induzir a cicatrização de feridas, uma vez que as plantas medicinais quando comparadas com as modernas terapias medicamentosa, apresentam menores efeitos adversos e baixo custo, quando comparado aos fármacos sintéticos, sendo essenciais para aquisição para a população de baixa renda. OBJETIVO: Avaliar o efeito associado entre o gel à base da casca do cajueiro (Anacardium occidentale L) e o ultrassom terapêutico sobre o processo de cicatrização de feridas cutâneas em camundongos. METODOLOGIA: 24 camundongos (Mus musculus) machos, pesando entre 40 a 50 gramas (g), provenientes do biotério da Faculdade de Ciências Médicas (FACIME), foram utilizados neste estudo. A pesquisa foi composta por 4 grupos (controle, ultrassom pulsado + fonorose, gel à base de cascas da Anacardium occidentale L e ultrassom pulsado), os quais foram tratados em diferentes tempos experimentais (8 e 15 dias). Após a eutanásia dos camundongos, realizou-se as análises macroscópica e microscópica, enquanto o extrato vegetal à base do caule do cajueiro (Anacardium occidentale L) foi avaliado através da prospecção fitoquímica. RESULTADOS: Observa-se que tanto na análise histológica quanto macroscópica, houve melhora do processo inflamatório inicial e aceleração do reparo tecidual nos grupos tratados com o UST, extrato, assim como, através da sua interação. CONCLUSÃO: Conclui-se que as terapias utilizadas no presente estudo, apresentaram resultados satisfatórios sobre o processo de reparação tecidual, os quais foram comprovados pela análise macroscópica e histológica.

An Intelligent Air Quality Sensing System for Open-Skin Wound Monitoring

There are many factors that may have a significant effect on the skin wound healing process. The environment is one of them. Although different previous research woks have highlighted the role of environmental elements such as humidity, temperature, dust, etc., in the process of skin wound healing, there is no predefined method available to identify the favourable or adverse environment conditions that seriously affect (positively or negatively) the skin wound healing process. In the current research work, an IoT-based approach is used to design an AQSS (Air Quality Sensing System) using sensors for the acquisition of real-time environment data, and the SVM (Support Vector Machine) classifier is applied to classify environments into one of the two categories, i.e., “favourable”, and “unfavourable”. The proposed system is also supported with an Android application to provide an easy-to-use interface. The proposed system provides an easy and simple means for patients to evaluate the environmental parameters and monitor their effects in the process of open skin wound healing.

The Spectrum of Scarring in Craniofacial Wound Repair.

Fibrosis is intimately linked to wound healing and is one of the largest causes of wound-related morbidity. While scar formation is the normal and inevitable outcome of adult mammalian cutaneous wound healing, scarring varies widely between different anatomical sites. The spectrum of craniofacial wound healing spans a particularly diverse range of outcomes. While most craniofacial wounds heal by scarring, which can be functionally and aesthetically devastating, healing of the oral mucosa represents a rare example of nearly scarless postnatal healing in humans. In this review, we describe the typical wound healing process in both skin and the oral cavity. We present clinical correlates and current therapies and discuss the current state of research into mechanisms of scarless healing, toward the ultimate goal of achieving scarless adult skin healing.

Influence of Porous Dressings Based on Butyric-Acetic Chitin Co-Polymer on Biological Processes In Vitro and In Vivo.

In spite of intensively conducted research allowing for the development of more and more advanced wound dressing materials, there is still a need for dressings that stimulate not only reparative and regenerative processes, but also have a positive effect on infected and/or difficult-to-heal wounds. Porous dressing materials based on butyric-acetic chitin co-polyester containing 90% of butyryl and 10% of acetyl groups (BAC 90/10) can also be included in the group mentioned above. Two types of dressings were obtained by the salt leaching method, i.e. a porous sponge Medisorb R and Medisorb Ag with an antibacterial additive. The aim of the study was to evaluate biological effects of porous Medisorb R and Medisorb Ag dressings under in vitro and in vivo conditions. In an in vitro biodegradation test, no mass loss of Medisorb R dressing was observed within 14 days of incubation in physiological fluids at 37 °C. However, on the basis of the FTIR (Fourier Transform Infrared Spectroscopy) tests, surface degradation of Medisorb R dressing was observed. Additionally, the antibacterial activity of the porous Medisorb Ag dressing containing microsilver as an antibacterial additive was confirmed. The in vivo studies included inflammatory activity, skin irritation and sensitisation tests, as well an assessment of local effect after contact with subcutaneous tissue up to 6 months and skin wounds up to 21 days. In the in vivo tests, the dressings exhibited neither effects of skin irritation nor sensitisation. Under macroscopic examination, in full thickness defects of subcutaneous tissue and skin, the dressings caused wound healing with no inflammation, undergoing the most gradual biodegradation between weeks 4 and 8, and the observed differences were statistically significant. In the histological assessment, a weakened, limited inflammatory process associated with degradation of the material has been observed. The process of skin wound healing under Medisorb R dressing in the early period was accelerated compared to that observed in the control group with a gauze dressing.

Periostin and CCN2 Scaffolds Promote the Wound Healing Response in the Skin of Diabetic Mice.

Nonhealing skin wounds remain a significant burden on health care systems, with diabetic patients 20 times as likely to undergo a lower extremity amputation due to impaired healing. Novel treatments that suppress the proinflammatory signature and induce the proliferative and remodeling phases are needed clinically. We demonstrate that the addition of periostin and CCN2 in a scaffold form increases closure rates of full-thickness skin wounds in diabetic mice, concomitant with enhanced angiogenesis. Our results demonstrate the efficacy of periostin- and CCN2-containing biomaterials to stimulate wound closure, which could represent a novel method for the treatment of diabetic skin wounds.

Expression of VEGF and TGF-β Genes in Skin Wound Healing Process Induced Using Phenytoin in Male Rats

Background: Phenytoin is one of the most important chemical drugs used for the treatment of skin wound. Objectives: In the present study, the molecular effect of phenytoin on the expression of VEGF and TGF-β genes was investigated. Methods: This study was conducted on 30 male rats with approximately equal body mass. Skin wounds were generated with an area of 2 cm and a depth of 0.5 mm on the back of the necks. The rats were divided into two case and control groups (15 rats in each group). Topical phenytoin was administered to the two groups 2 times a day (1%) and Vaseline (as control group). Each of control and treated groups were divided into three subgroups and the rats were euthanized with chloroform on days 7, 14, and 21 of post-wounding. The wounds were harvested from control and treated rats. After homogenization of the tissues, RNA was extracted, purified, converted to cDNA, and the relative expression of VEGF and TGF-β genes in phenytoin and control groups was evaluated by real-time PCR. The gene expression was evaluated on days 7, 14, and 21. Results: Increased expression of VEGF and TGF-β in the first week and decreased expression of both genes in the third week were observed in the phenytoin-treated group compared with the control group (P < 0.001). Conclusions: Regarding the results of the expression of both TGF-β and VEGF genes, there is a significant relationship between the expression of these two genes and the rate of wound healing in rats.

Wound healing effects of topical Vitamin K: A randomized controlled trial.

BACKGROUND:The incidence of acute and chronic wounds has rapidly increased which treatment remains as health problem. Previously, we reported the healing effect of Vitamin K in experimental animal models. The aim of this study was to investigate the effects of topical Vitamin K on skin wound healing process in patients.MATERIALS AND METHODS:Sixty-three patients with indication for high-frequency electrocautery were enrolled in this randomized controlled trial. The patients were divided randomly into three groups. All the patients underwent high-frequency electrocautery treatment. Then, the patients in the A group received 1% Vitamin K cream, the patients in the B group received 1% phenytoin cream. Furthermore, the patients in the control group received Eucerin. The wound status (width and the time of recovery) and complications in the three groups were evaluated 2 weeks after procedure by a dermatologist.RESULTS:The effects produced by the topical Vitamin K showed a significant (P < 0.05) healing when compared with Eucerin group in parameters such as wound contraction and time to full recovery. Moreover, the healing time did not differ between phenytoin and Vitamin K groups (P = 0.16).CONCLUSION:A randomized, controlled trial suggests that topical application of Vitamin K significantly reduces healing time in patients.

Effect of Hydroethanolic Extract of Nigella sativa L. on Skin Wound Healing Process in Diabetic Male Rats.

Background:The aim of this study was to investigate the effect of hydroethanolic Nigella sativa L. extract on skin wound healing in diabetic male rats.MethodsThis experimental study was conducted on 49 male Wistar rats weighing 220–250 g divided into 7 groups of 7 each: control (nondiabetic untreated), sham (nondiabetic eucerin-treated), nondiabetic phenytoin (1%)-treated, diabetic untreated, and three diabetic groups treated independently with phenytoin 1%, hydroethanolic N. sativa extracts 20% or 40%. Diabetes was induced with 60 mg/kg streptozosin in one administration. After anesthesia, 2 × 1 cm2 wounds were made on the rats’ backs and each group was administered with its own respective treatment until the wounds were healed completely. Tissue specimens were prepared for histological examinations. The areas of the wounds were measured every 3 days. The data were analyzed by ANOVA and Tukey's post-hoc test.Results:The mean duration of wound healing was 27 and 24 days for diabetic untreated and diabetic phenytoin-treated groups, respectively. Wounds were healed completely in nondiabetic untreated, sham, and nondiabetic phenytoin-treated groups on days 23, 24, and 21, respectively. The shortest duration of wound healing was seen in diabetic N. sativa extract (40%)-treated group (15 days) followed by diabetic N. sativa (20%)-treated group (18 days). These two groups were found to have the lowest mean wound area during the study with a significant difference from mean wound area in the controls (P < 0.05).Conclusions:N. sativa extract significantly promoted wound healing in diabetic rats in comparison with control groups. Although the beneficial mechanism of the promotion of wound healing was not specifically studied, it is believed that the anti-inflammatory and antimicrobial properties of N. sativa would contribute to this enhanced wound healing.

THE DYNAMICS OF WOUND HEALING IN THE TREATMENT WITH THE OINTMENT WITH A DRY EXTRACT OF POTENTILLA

Aim. The study was designed for the evaluation of the effect of ointments with dry extracts of potentilla on the dynamics of the healing process of full-thickness skin wounds.Materials and methods. The wound healing activity estimation of the proposed dosage form was conducted on white Wistar rats. The results of macroscopic studies (the area of the wound defect, the state of the scab, the presence of hemorrhage beneath it, the degree of inflammatory processes in the underlying tissues, including deeply located tissue structures, up to the muscle elements) and the results of histological examination were the criterion for evaluating the effectiveness of the wound healing agent. In the course of the experiment, the animals were divided into 4 groups: the main group (treatment with the ointment with a dry extract of potentilla), control group No. 1 (treatment with the ointment base), control group No. 2 (without treatment), and control group No. 3 (treatment with the «Chlorophyllipt» drug.Results. The results of the macroscopic and histological studies made it possible to conclude that the wound healing process in the treatment with the ointment with a dry extract of potentilla had a number of features. The proposed dosage form enhanced the regeneration of the multilayered squamous epithelium, accelerated the maturation of the granulation tissue, and eliminated the inflammation and infiltration in the first days of treatment, which led to a significant reduction in the healing time when it was applied (15-18 days). In the animals of the control groups No. 1 and No. 2, the described processes occurred much more slowly, and inflammatory infiltration persisted almost throughout the entire experiment. The wound surface was healed on the 27-30th day. A lot of common features were noted in the mechanism and timing of wound healing in the treatment with the ointment with a dry extract of potentilla and a reference preparation – «Сhlorophyllipt». Conclusion. The ointment with a dry extract of potentilla significantly speeds up the healing process of full-thickness skin wounds.

Simulating Inflammation in a Wound Microenvironment Using a Dermal Wound-on-a-Chip Model.

Considerable progress has been made in the field of microfluidics to develop complex systems for modeling human skin and dermal wound healing processes. While microfluidic models have attempted to integrate multiple cell types and/or 3D culture systems, to date they have lacked some elements needed to fully represent dermal wound healing. This paper describes a cost-effective, multicellular microfluidic system that mimics the paracrine component of early inflammation close to normal wound healing. Collagen and Matrigel are tested as materials for coating and adhesion of dermal fibroblasts and human umbilical vein endothelial cells (HUVECs). The wound-on-chip model consists of three interconnecting channels and is able to simulate wound inflammation by adding tumor necrosis factor alpha (TNF-α) or by triculturing with macrophages. Both the approaches significantly increase IL-1β, IL-6, IL-8 in the supernatant (p < 0.05), and increases in cytokine levels are attenuated by cotreatment with an anti-inflammatory agent, Dexamethasone. Incorporation of M1 and M2 macrophages cocultured with fibroblasts and HUVECs leads to a stimulation of cytokine production as well as vascular structure formation, particularly with M2 macrophages. In summary, this wound-on-chip system can be used to model the paracrine component of the early inflammatory phase of wound healing and has the potential for the screening of anti-inflammatory compounds.

Wound healing mechanism in Mongolian gerbil skin.

The skin wound healing ability of animals differs depending on the environment. The gerbil wound model showed a different wound healing mechanism than was known thus far. Many other wound healing mechanisms have been found to involve transforming growth factor-beta 1 (TGF-β1). However, in the wound healing of gerbil skin, the expression of TGF-β1 seems to be not enough compared to mouse. In this study, we compared the wound healing process of gerbil and mouse back skin. At 3 days after wounding, the TGF-β1 level was downregulated in gerbil skin wound healing compared mouse. In addition, gerbils have fewer integrin signals related to the regulation of TGF-β activation and signaling. Despite lacking these factors, the wound healing results in the gerbil are similar to those for skin wound healing in mice. In contrast, in gerbil skin wound healing, the basal skin layer showed hyperplasia in re-epithelialization, more production of hair follicles, and low probability of collagen infiltration at the late stages of wound healing. These data suggest that different wound healing mechanisms are present in the mammals.

Pannexin-3 Deficiency Delays Skin Wound Healing in Mice due to Defects in Channel Functionality

Pannexin-3 (Panx3) is a gap junction protein that is required for regulating cell cycle exit and the differentiation of osteoblasts and chondrocytes during skeletal development. However, the role of Panx3 in skin tissue regeneration remains unclear. After dorsal skin punch biopsies, Panx3-knockout mice exhibited a significant delay in wound healing with insufficient re-epithelialization, decreased inflammatory reaction, and reduced collagen remodeling. Panx3 expression coincided with inflammatory reactions both invivo and invitro. By applying exogenous tumor necrosis factor-α to mimic inflammation invitro, Panx3 expression was induced in HaCaT cells. In addition, Panx3 depletion reduced epithelial-mesenchymal transition during skin wound healing. A protein essential for signaling in epithelial-mesenchymal transition, transforming growth factor-β interacted with Panx3 by modulating intracellular adenosine triphosphate levels and thereby enhanced HaCaT cell migration ability with Panx3 overexpression. In conclusion, Panx3 plays a key role in the skin wound healing process by controlling keratinocytes and keratinocyte-mesenchyme cross-talk via hemichannel and endoplasmic reticulum Ca2+ channel functions, which differs from another gap junction, connexin 43 (Cx43), during skin wound healing.

Dectin-2–Mediated Signaling Leads to Delayed Skin Wound Healing through Enhanced Neutrophilic Inflammatory Response and Neutrophil Extracellular Trap Formation

Dendritic cell-associated C-type lectin-2 (i.e., dectin-2) recognizes fungal polysaccharides, including α-mannan. Dectin-2-mediated recognition of fungi, such as Candida albicans, leads to NF-κB activation, which induces production of inflammatory cytokines. However, the role of dectin-2 in skin wound healing remains unclear. In this study, we sought to determine how dectin-2 deficiency and the administration of α-mannan affected the wound healing process. Full-thickness wounds were created on the backs of wild type C57BL/6 and dectin-2-deficient mice. We analyzed wound closure, histological findings, and re-epithelialization. We also examined the neutrophilic inflammatory responses and neutrophil extracellular trap (NET)-osis at the wound sites after administration of α-mannan. The percent wound closure and re-epithelialization was significantly accelerated in dectin-2-knockout mice compared with wild-type mice on days 3 and 5 after wounding. In contrast, administration of α-mannan delayed wound closure in wild-type mice, and these responses were canceled in dectin-2-knockout mice. Furthermore, mice administered α-mannan, neutrophil infiltration was prolonged, and the expression of citrullinated histone, an indicator of NETosis, at the wound sites was accelerated. Administration of a neutrophil elastase inhibitor significantly improved the delayed wound healing caused by α-mannan. These results suggest that dectin-2 may have a deep impact on the skin wound healing process through regulation of neutrophilic responses.

Embryonic Stem Cell-Derived mmu-miR-291a-3p Inhibits Cellular Senescence in Human Dermal Fibroblasts Through the TGF-β Receptor 2 Pathway.

Senescent cells accumulate in various tissues over time and contribute to tissue dysfunction and aging-associated phenotypes. Accumulating evidence suggests that cellular senescence can be inhibited through pharmacological intervention, as well as through treatment with soluble factors derived from embryonic stem cells (ESCs). In an attempt to investigate the anti-senescence factors secreted by ESCs, we analyzed mouse ESC-derived extracellular microRNAs in conditioned medium via microRNA array analysis. We selected mmu-miR-291a-3p as a putative anti-senescence factor via bioinformatics analysis. We validated its inhibitory effects on replicative, Adriamycin-induced, and ionizing radiation-induced senescence in human dermal fibroblasts. Treatment of senescent cells with mmu-miR-291a-3p decreased senescence-associated β-galactosidase activity, enhanced proliferative potential, and reduced mRNA and protein expression of TGF-β receptor 2, p53, and p21. mmu-miR-291a-3p in conditioned medium was enclosed in ESC-derived exosomes and exosomes purified from ESC conditioned medium inhibited cellular senescence. The inhibitory effects of mmu-miR-291a-3p were mediated through the TGF-β receptor 2 signaling pathway. Hsa-miR-371a-3p and hsa-miR-520e, the human homologs of mmu-miR-291a-3p, showed similar anti-senescence activity. Furthermore, mmu-miR-291a-3p accelerated the excisional skin wound healing process in aged mice. Our results indicate that the ESC-derived mmu-miR-291a-3p is a novel candidate agent that can be utilized for cell-free therapeutic intervention against aging and aging-related diseases.

JAM-A knockdown accelerates the proliferation and migration of human keratinocytes, and improves wound healing in rats via FAK/Erk signaling

Junctional adhesion molecule-A (JAM-A) belongs to the immunoglobulin superfamily, it predominantly exists at the tight junctions of epithelial and endothelial cells. JAM-A is known to regulate leukocyte trans-endothelial migration, however, how it affects the proliferation and migration of keratinocytes, the two essential steps during wound healing, has less been explored. In this study, we showed that JAM-A was significantly expressed in normal skin epidermis. RNAi-mediated JAM-A knockdown remarkably promoted the proliferation and migration of keratinocytes. We also found that loss of JAM-A increased the protein levels of p-FAK, p-Erk1/2, and p-JNK; however, FAK inhibitor PF-562271 restrained the expression of p-FAK and p-Erk1/2 elevated by JAM-A RNAi, but not p-JNK, and also slowed down keratinocyte proliferation and migration. Finally, in a rat wound model we showed that absence of JAM-A significantly promoted the wound healing process, while the use of PF-562271 or Erk1/2 inhibitor PD98059 repressed those effects. These data collectively demonstrate that suppressing JAM-A expression could promote the proliferation and migration of keratinocytes and accelerate the healing process of rat skin wounds, potentially via FAK/Erk pathway, indicating that JAM-A might serve as a potential therapeutic target for the treatment of chronic refractory wounds.

Nanostructured scaffold with biomimetic and antibacterial properties for wound healing produced by 'green electrospinning'.

Wound healing is a complex process that often requires treatment with antibacterial agents to avoid infection, which affects the optimal tissue regeneration process. Ideal scaffolds for wound healing treatment should combine biomimetic features to ensure the tissue growth on properly designed extracellular matrix (ECM)-like scaffolds and antibacterial properties in order to avoid bacterial colonization. In this work, gelatin cross-linked nanofibers (GL-nanofibres), with diameters ranging from 200 to 300 nm, were prepared via a "green electrospinning technique" to mimic the structure and composition of the extracellular matrix (ECM), and promote the normal skin wound healing process. Nanofibres were doped with two antibacterial agents (gentamicin sulphate or silver nanoparticles) to achieve an antibacterial effect against Gram + and Gram- bacteria. The ECM-mimicking structure of GL-nanofibres was not affected by the presence of the antibacterial agents, which were homogeneously distributed within the mats as shown by SEM and EDS. The antibacterial properties of the developed matrices were confirmed using 4 strains (S. aureus, S. epidermidis, P. aeruginosa and E. coli) while the biocompatibility of the developed substrates and their ability to induce cell growth was assessed using Neonatal Normal Human Dermal Fibroblasts (NHDF-Neo).