Dermal transforming growth factor-beta responsiveness mediates wound contraction and epithelial closure

Mesenchymal stem cells and their exosomes: a novel approach to skin regeneration via signaling pathways activation

Accelerating wound healing is a crucial objective in surgical and regenerative medicine. The wound healing process involves three key stages: inflammation, cell proliferation, and tissue repair. Mesenchymal stem cells (MSCs) have demonstrated significant therapeutic potential in promoting tissue regeneration, particularly by enhancing epidermal cell migration and proliferation. However, the precise molecular mechanisms underlying MSC-mediated wound healing remain unclear. This review highlights the pivotal role of MSCs and their exosomes in wound repair, with a specific focus on critical signaling pathways, including PI3K/Akt, WNT/β-catenin, Notch, and MAPK. These pathways regulate essential cellular processes such as proliferation, differentiation, and angiogenesis. Moreover, in vitro and in vivo studies reveal that MSCs accelerate wound closure, enhance collagen deposition, and modulate immune responses, contributing to improved tissue regeneration. Understanding these mechanisms provides valuable insights into MSC-based therapeutic strategies for enhancing wound healing.

Assessment of Agrimonia eupatoria L. and Lipophosphonoxin (DR-6180) Combination for Wound Repair: Bridging the Gap Between Phytomedicine and Organic Chemistry

Agrimonia eupatoria L. (AE) has a rich tradition of use in wound healing improvement across various cultures worldwide. In previous studies, we revealed that Agrimonia eupatoria L. water extract (AE) possesses a rich polyphenolic composition, displaying remarkable antioxidant properties. Our investigations also demonstrated that lipophosphonoxin (LPPO) exhibited antibacterial efficacy in vitro while preserving the proliferation and differentiation of fibroblasts and keratinocytes. Building upon our prior findings, in this study, we intended to examine whether a combination of AE and LPPO could enhance skin wound healing while retaining antibacterial attributes. The antibacterial activity of AE/LPPO against Staphylococcus aureus was evaluated, alongside its effects on fibroblast-to-myofibroblast transition, the formation of extracellular matrix (ECM), and endothelial cells and keratinocyte proliferation/phenotype. We also investigated AE/LPPO's impact on TGF-β1 and VEGF-A signaling in keratinocytes/fibroblasts and endothelial cells, respectively. Additionally, wound healing progression in rats was examined through macroscopic observation and histological analysis. Our results indicate that AE/LPPO promotes myofibroblast-like phenotypic changes and augments ECM deposition. Clinically relevant, the AE/LPPO did not disrupt TGF-β1 and VEGF-A signaling and accelerated wound closure in rats. Notably, while AE and LPPO individually exhibited antibacterial activity, their combination did not lead to synergism, rather decreasing antibacterial activity, warranting further examination. These findings underscore substantial wound healing improvement facilitated by AE/LPPO, requiring further exploration in animal models closer to human physiology.

Nrf2 Activation in Keratinocytes: A Central Role in Diabetes-Associated Wound Healing

Wound healing is a complex biological process crucial for tissue repair, wherein keratinocytes play a pivotal role in initiating, sustaining and completing the cascade. Various local and systemic factors, such as lifestyle, age metabolic disorders and vascular insufficiency, can influence this process, and in the context of diabetic wounds, disrupted biological mechanisms, including inflammation, tissue hypoxia, decrease in collagen production along with increased oxidative stress and keratinocyte dysfunction, contribute to delayed healing. During re-epithelialisation, keratinocytes undergo rapid multiplication and migration, forming a dense hyperproliferative epithelial layer that restores the epidermal barrier. Nuclear factor-erythroid 2-related factor (Nrf2), a vital transcription factor, emerges as a central regulator in managing antioxidant proteins and detoxifying enzymes, serving as a guardian against elevated reactive oxygen species (ROS) levels during stress. Nrf2 also orchestrates angiogenesis and anti-inflammatory responses crucial for wound repair. Studies demonstrate that under high-glucose conditions, Nrf2 activation promotes wound healing by enhancing cell proliferation and migration while reducing apoptosis. Nrf2 activators stimulate endogenous antioxidant production, thereby mitigating oxidative stress. Furthermore, Nrf2 upregulation is associated with decreased expression of cytokines such as TNF-α and IL- 6. Recent research underscores the potential of bioactive molecules, including dietary polyphenols, traditional medicinal compounds and pharmacological agents, in activating Nrf2 and preventing diseases such as diabetes due to their robust antioxidative properties. This review aims to investigate the activation of Nrf2 by these bioactive molecules in cultured keratinocytes and animal models, elucidating the key molecular regulatory mechanisms involved in alleviating oxidative stress and facilitating the diabetic wound healing process. Understanding these complex pathways may offer insights into novel therapeutic strategies for enhanced wound healing in diabetes-associated complications.

Healing the diabetic wound: Unlocking the secrets of genes and pathways

Diabetic wounds (DWs) are open sores that can occur anywhere on a diabetic patient's body. They are often complicated by infections, hypoxia, oxidative stress, hyperglycemia, and reduced growth factors and nucleic acids. The healing process involves four phases: homeostasis, inflammation, proliferation, and remodeling, regulated by various cellular and molecular events. Numerous genes and signaling pathways such as VEGF, TGF-β, NF-κB, PPAR-γ, MMPs, IGF, FGF, PDGF, EGF, NOX, TLR, JAK-STAT, PI3K-Akt, MAPK, ERK, JNK, p38, Wnt/β-catenin, Hedgehog, Notch, Hippo, FAK, Integrin, and Src pathways are involved in these events. These pathways and genes are often dysregulated in DWs leading to impaired healing. The present review sheds light on the pathogenesis, healing process, signaling pathways, and genes involved in DW. Further, various therapeutic strategies that target these pathways and genes via nanotechnology are also discussed. Additionally, clinical trials on DW related to gene therapy are also covered in the present review.

Hair-follicle associated pluripotent (HAP)-cell-sheet implantation enhanced wound healing in diabetic db/db mice

Diabetes often results in chronic ulcers that fail to heal. Effective treatment for diabetic wounds has not been achieved, although stem-cell-treatment has shown promise. Hair-follicle-associated-pluripotent (HAP)-stem-cells from bulge area of mouse hair follicle have been shown to differentiate into keratinocytes, vascular endothelial cells, smooth muscle cells, and some other types of cells. In the present study, we developed HAP-cell-sheets to determine their effects on wound healing in type-2 diabetes mellitus (db/db) C57BL/6 mouse model. Flow cytometry analysis showed cytokeratin 15 expression in 64% of cells and macrophage expression in 3.6% of cells in HAP-cell-sheets. A scratch cell migration assay in vitro showed the ability of fibroblasts to migrate and proliferate was enhanced when co-cultured with HAP-cell-sheets. To investigate in vivo effects of the HAP-cell-sheets, they were implanted into 10 mm circular full-thickness resection wounds made on the back of db/db mice. Wound closure was facilitated in the implanted group until day 16. The thickness of epithelium and granulation tissue volume at day 7 were significantly increased by the implantation. CD68 positive area and TGF-β1 positive area were significantly increased; meanwhile, iNOS positive area was reduced at day 7 in the HAP-cell-sheets implanted group. After 21 days, CD68 positive areas in the implanted group were reduced to under the control group level, and TGF-β1 positive area had no difference between the two groups. These observations strongly suggest that the HAP-cell-sheets implantation is efficient to facilitate early macrophage activity and to suppress inflammation level. Using immuno-double-staining against CD34 and α-SMA, we found more vigorous angiogenesis in the implanted wound tissue. The present results suggest autologous HAP-cell-sheets can be used to heal refractory diabetic ulcers and have clinical promise.

TEM1/endosialin/CD248 promotes pathologic scarring and TGF-β activity through its receptor stability in dermal fibroblasts

BACKGROUND

Pathologic scars, including keloids and hypertrophic scars, represent a common form of exaggerated cutaneous scarring that is difficult to prevent or treat effectively. Additionally, the pathobiology of pathologic scars remains poorly understood. We aim at investigating the impact of TEM1 (also known as endosialin or CD248), which is a glycosylated type I transmembrane protein, on development of pathologic scars.

METHODS

To investigate the expression of TEM1, we utilized immunofluorescence staining, Western blotting, and single-cell RNA-sequencing (scRNA-seq) techniques. We conducted in vitro cell culture experiments and an in vivo stretch-induced scar mouse model to study the involvement of TEM1 in TGF-β-mediated responses in pathologic scars.

RESULTS

The levels of the protein TEM1 are elevated in both hypertrophic scars and keloids in comparison to normal skin. A re-analysis of scRNA-seq datasets reveals that a major profibrotic subpopulation of keloid and hypertrophic scar fibroblasts greatly expresses TEM1, with expression increasing during fibroblast activation. TEM1 promotes activation, proliferation, and ECM production in human dermal fibroblasts by enhancing TGF-β1 signaling through binding with and stabilizing TGF-β receptors. Global deletion of Tem1 markedly reduces the amount of ECM synthesis and inflammation in a scar in a mouse model of stretch-induced pathologic scarring. The intralesional administration of ontuxizumab, a humanized IgG monoclonal antibody targeting TEM1, significantly decreased both the size and collagen density of keloids.

CONCLUSIONS

Our data indicate that TEM1 plays a role in pathologic scarring, with its synergistic effect on the TGF-β signaling contributing to dermal fibroblast activation. Targeting TEM1 may represent a novel therapeutic approach in reducing the morbidity of pathologic scars.

Therapeutic role of growth factors in treating diabetic wound

Wounds in diabetic patients, especially diabetic foot ulcers, are more difficult to heal compared with normal wounds and can easily deteriorate, leading to amputation. Common treatments cannot heal diabetic wounds or control their many complications. Growth factors are found to play important roles in regulating complex diabetic wound healing. Different growth factors such as transforming growth factor beta 1, insulin-like growth factor, and vascular endothelial growth factor play different roles in diabetic wound healing. This implies that a therapeutic modality modulating different growth factors to suit wound healing can significantly improve the treatment of diabetic wounds. Further, some current treatments have been shown to promote the healing of diabetic wounds by modulating specific growth factors. The purpose of this study was to discuss the role played by each growth factor in therapeutic approaches so as to stimulate further therapeutic thinking.

Effect of Flaxseed on TGF-Β, IL-6, and MMP9 Genes Expression during Wound Healing Process in Rabbits

BACKGROUND: Wound healing is a natural restorative response to tissue injury, and it involves regulated order of cellular and biochemical actions to reinstate tissue after injury, which involves resurfacing reconstitution, and restoration of tensile strength of injured skin. Normal and impaired wound healing post-significant problems related to healthcare and expenditure. Most of the chemical medications which widely used for wound healing might cause unwanted side effects with prolonged use such as hyper scarring, thus studies using natural products are now deemed important. Flaxseed is a natural product that enhances the immune system functioning against different diseases. Nevertheless, limited studies have been done looking into the response triggered by immune cells and the wound-healing-related genes with the use of flaxseed extract onto the wounded skin for the healing process. AIM: The main objective of this study is to analyze the expression of wound healing-related genes during different stages of the wound healing process induced by flaxseed in vivo. METHODS: The effect of flaxseed oil in the early stages (day 4 and 7) and late stages (day 14) of wound healing was explored on New Zealand white rabbits by creating a longitudinal full thickness wound on their back. The gene expression profiles of transforming growth factor-beta (TGF-β), IL-6, and metalloproteinase (MMP9) genes which have roles in wound healing through inflammation, proliferation, and remodeling were studied by polymerase chain reaction method. RESULTS: Flaxseed extract has significant effects in up-regulating anti-inflammatory marker TGF-β in wounds. Flaxseed oil also reduces the expression level of MMP9 on day 14 of wound healing. CONCLUSIONS: This suggests that flaxseed extract has the potential to promote wound healing through the regulation of TGF-β and MMP9 in vivo.

Phospholipid-grafted PLLA electrospun micro/nanofibers immobilized with small extracellular vesicles from rat adipose mesenchymal stem cells promote wound healing in diabetic rats

Small extracellular vesicles (sEVs) derived from mesenchymal stem cells (MSCs) can deliver a variety of bioactive factors to create a favorable local microenvironment, thereby holding huge potential in chronic wound repair. However, free sEVs administrated intravenously or locally are usually cleared rapidly, resulting in an insufficient duration of the efficacy. Thus, strategies that enable optimized retention and release profiles of sEVs at wound sites are desirable. Herein, we fabricated novel functional phosphoethanolamine phospholipid-grafted poly-l-lactic acid micro/nanofibers (DSPE-PLLA) to carry and retain sEVs from rat adipose MSCs, enabling the slow local release of sEVs. Our results showed that sEVs@DSPE-PLLA promoted the proliferation, migration and gene expression (Col I, Col III, TGF-β, α-SMA, HIF-1α) of fibroblasts. It also promoted keratinocyte proliferation. In addition, sEVs@DSPE-PLLA helped polarize macrophages toward the M2 phenotype by increasing the expression of anti-inflammatory genes (Arginase 1, CD 206, IL-10) and inhibiting the expression of pro-inflammatory genes (IL-1β, TNF-α). Further in vivo study in diabetic rat models showed that sEVs@DSPE-PLLA improved the wound-healing process by alleviating the inflammatory responses, stimulating cell proliferation, collagen deposition and angiogenesis. These results highlight the potential of using DSPE-grafted scaffolds for extracellular vesicle immobilization and suggest sEVs@DSPE-PLLA micro/nanofibers as promising functional wound dressings for diabetic wounds.

Macrophage Phenotypes in Normal and Diabetic Wound Healing and Therapeutic Interventions

Macrophage differentiation and polarization are essential players in the success of the wound-healing process. Acute simple wounds progress from inflammation to proliferation/regeneration and, finally, to remodeling. In injured skin, macrophages either reside in the epithelium or are recruited from monocytes. Their main role is supported by their plasticity, which allows them to adopt different phenotypic states, such as the M1-inflammatory state, in which they produce TNF and NO, and the M2-reparative state, in which they resolve inflammation and exhibit a reparative function. Reparative macrophages are an essential source of growth factors such as TGF-β and VEGF and are not found in nonhealing wounds. This review discusses the differences between macrophage phenotypes in vitro and in vivo, how macrophages originate, and how they cross-communicate with other cellular components in a wound. This review also highlights the dysregulation of macrophages that occurs in nonhealing versus overhealing wounds and fibrosis. Then, the therapeutic manipulation of macrophages is presented as an attractive strategy for promoting healing through the secretion of growth factors for angiogenesis, keratinocyte migration, and collagen production. Finally, Hoxa3 overexpression is discussed as an example of the therapeutic repolarization of macrophages to the normal maturation state and phenotype with better healing outcomes.

Novel lipophosphonoxin-loaded polycaprolactone electrospun nanofiber dressing reduces Staphylococcus aureus induced wound infection in mice

Active wound dressings are attracting extensive attention in soft tissue repair and regeneration, including bacteria-infected skin wound healing. As the wide use of antibiotics leads to drug resistance we present here a new concept of wound dressings based on the polycaprolactone nanofiber scaffold (NANO) releasing second generation lipophosphonoxin (LPPO) as antibacterial agent. Firstly, we demonstrated in vitro that LPPO released from NANO exerted antibacterial activity while not impairing proliferation/differentiation of fibroblasts and keratinocytes. Secondly, using a mouse model we showed that NANO loaded with LPPO significantly reduced the Staphylococcus aureus counts in infected wounds as evaluated 7 days post-surgery. Furthermore, the rate of degradation and subsequent LPPO release in infected wounds was also facilitated by lytic enzymes secreted by inoculated bacteria. Finally, LPPO displayed negligible to no systemic absorption. In conclusion, the composite antibacterial NANO-LPPO-based dressing reduces the bacterial load and promotes skin repair, with the potential to treat wounds in clinical settings.

The senescence-associated secretory phenotype: Fueling a wound that never heals

Wound healing is impaired with advanced age and certain chronic conditions, such as diabetes and obesity. Moreover, common cancer treatments, including chemotherapy and radiation, can cause unintended tissue damage and impair wound healing. Available wound care treatments are not always effective, as some wounds fail to heal or recur after treatment. Hence, a more thorough understanding of the pathophysiology of chronic, nonhealing wounds may offer new ideas for the development of effective wound care treatments. Cancers are sometimes referred to as wounds that never heal, sharing mechanisms similar to wound healing. We describe in this review how cellular senescence and the senescence-associated secretory phenotype (SASP) contribute to chronic wounds versus cancer.

Topical Application of Conditioned Medium from Hypoxically Cultured Amnion-Derived Mesenchymal Stem Cells Promotes Wound Healing in Diabetic Mice

BACKGROUND

Mesenchymal stem cells or their conditioned medium improve chronic wound healing, and their effect is enhanced by hypoxia. Diabetic foot ulcers are chronic wounds characterized by abnormal and delayed healing, which frequently require amputation. The authors evaluated the effect of topical application of conditioned medium from hypoxically cultured amnion-derived mesenchymal stem cells on wound healing in diabetic mice.

METHODS

Amnion-derived mesenchymal stem cells were cultured under 21% oxygen to prepare normoxic conditioned medium and under 1% oxygen to prepare hypoxic conditioned medium. Hydrogels containing standard medium, normoxic conditioned medium, or hypoxic conditioned medium were topically applied to excisional wounds of mice with streptozotocin-induced diabetes. Ulcer tissues were harvested on day 9; immunohistochemical and quantitative polymerase chain reaction analyses were performed to analyze angiogenesis, inflammatory cell infiltration, and expression levels of inflammation-related genes.

RESULTS

Hypoxic conditioned medium significantly enhanced wound closure, increased capillary density and epithelization, and reduced macrophage infiltration. It also tended to reduce the infiltration of neutrophils and enhance the infiltration of regulatory T cells; it showed a tendency to downregulate the expression of the inflammation-related genes interleukin-1β, interleukin-6, chemokine ligand 1, and chemokine ligand 2. Normoxic conditioned medium exhibited similar effects, although they were of lesser magnitude than those of hypoxic conditioned medium.

CONCLUSIONS

Hydrogels containing hypoxically cultured, amnion-derived mesenchymal stem cell conditioned medium accelerated wound healing in diabetic mice by enhancing angiogenesis, accelerating epithelization, and suppressing inflammation. Therefore, topical application of amnion mesenchymal stem cell-derived hypoxic conditioned medium could be a novel treatment for diabetic foot ulcers.

Interplay between Cell-Surface Receptors and Extracellular Matrix in Skin

Skin consists of the epidermis and dermis, which are connected by a specialized basement membrane-the epidermal basement membrane. Both the epidermal basement membrane and the underlying interstitial extracellular matrix (ECM) created by dermal fibroblasts contain distinct network-forming macromolecules. These matrices play various roles in order to maintain skin homeostasis and integrity. Within this complex interplay of cells and matrices, cell surface receptors play essential roles not only for inside-out and outside-in signaling, but also for establishing mechanical and biochemical properties of skin. Already minor modulations of this multifactorial cross-talk can lead to severe and systemic diseases. In this review, major epidermal and dermal cell surface receptors will be addressed with respect to their interactions with matrix components as well as their roles in fibrotic, inflammatory or tumorigenic skin diseases.

Role of TGF-β in Skin Chronic Wounds: A Keratinocyte Perspective

Chronic wounds are characterized for their incapacity to heal within an expected time frame. Potential mechanisms driving this impairment are poorly understood and current hypotheses point to the development of an unbalanced milieu of growth factor and cytokines. Among them, TGF-β is considered to promote the broadest spectrum of effects. Although it is known to contribute to healthy skin homeostasis, the highly context-dependent nature of TGF-β signaling restricts the understanding of its roles in healing and wound chronification. Historically, low TGF-β levels have been suggested as a pattern in chronic wounds. However, a revision of the available evidence in humans indicates that this could constitute a questionable argument. Thus, in chronic wounds, divergences regarding skin tissue compartments seem to be characterized by elevated TGF-β levels only in the epidermis. Understanding how this aspect affects keratinocyte activities and their capacity to re-epithelialize might offer an opportunity to gain comprehensive knowledge of the involvement of TGF-β in chronic wounds. In this review, we compile existing evidence on the roles played by TGF-β during skin wound healing, with special emphasis on keratinocyte responses. Current limitations and future perspectives of TGF-β research in chronic wounds are discussed.

Dietary Suberic Acid Protects Against UVB-Induced Skin Photoaging in Hairless Mice

Ultraviolet (UV) radiation is a major cause of skin photoaging, which is mainly characterized by dryness and wrinkle formation. In the current study, we investigated the anti-photoaging effects of dietary suberic acid, a naturally occurring photochemical, using UVB-irradiated hairless mice. Mice were exposed to UVB three times weekly and fed diets containing three different suberic acid concentrations (0.05%, 0.1% and 0.2%) for 10 weeks. It was found that suberic acid inhibited UVB-induced skin dryness, wrinkle formation, and epidermal thickness in hairless mice. In parallel with phenotypic changes, suberic acid attenuated UVB-induced matrix metalloproteinase (MMP) genes (MMP1a, MMP1b, MMP3, and MMP9), while accelerating collagen genes including collagen type I alpha 1 chain (COL1A1), COL1A2, and COL3A1 and hyaluronic acid synthases genes (HAS1, HAS2 and HAS3). We further demonstrated that suberic acid upregulated the molecules involved in the transforming growth factor-β (TGF-β)/SMAD pathway, but downregulated the molecules participating in the mitogen-activated protein kinase (MAPK)/activator protein 1 (AP-1) signaling in UVB-irritated hairless mice. Collectively, we propose that suberic acid may be a promising agent for treating skin photoaging.

Experimental models for cutaneous hypertrophic scar research

Human skin wound repair may result in various outcomes with most of them leading to scar formation. Commonly seen in many cutaneous wound healing cases, hypertrophic scars are considered as phenotypes of abnormal wound repair. To prevent the formation of hypertrophic scars, efforts have been made to understand the mechanism of scarring following wound closure. Numerous in vivo and in vitro models have been created to facilitate investigations into cutaneous scarring and the development of antiscarring treatments. To select the best model for a specific study, background knowledge of the current models of hypertrophic scars is necessary. In this review, we describe in vivo and in vitro models for studying hypertrophic scars, as well as the distinct characteristics of these models. The choice of models for a specific study should be based on the characteristics of the model and the goal of the study. In general, in vivo animal models are often used in phenotypical scar formation analysis, development of antiscarring treatment, and functional analyses of individual genes. In contrast, in vitro models are chosen to pathway identification during scar formation as well as in high-throughput analysis in drug development. Besides helping investigators choose the best scarring model for their research, the goal of this review is to provide knowledge for improving the existing models and development of new models. These will contribute to the progress of scarring studies.

Low Degree Hyaluronic Acid Crosslinking Inducing the Release of TGF-Β1 in Conditioned Medium of Wharton's Jelly-Derived Stem Cells

BACKGROUND:

Presently, the application of stem cells and their paracrine effect for anti-ageing therapy has commenced. Wharton’s jelly-derived stem cell conditioned medium (WJSCs-CM) is renowned for increasing proliferation, migrate ageing skin fibroblasts and increase consumption of extracellular transforming growth factor-β (TGF-β). With more than 85% of frequently used dermal filler procedures are hyaluronic acid fillers (HA), a mixture of both with optimal HA crosslinking degree has not yet been identified.

AIM:

This study aimed to determine the discrepancies in the results of various HA crosslinking degree in WJSCs-CM concerning various levels of growth factors (GF).

METHODS:

Conditioned medium was obtained from mesenchymal stem cells Wharton’s jelly of the newborn umbilical cord with caesarean section procedure, fabricated with hypoxia method (HCM). HA was obtained from preparations on the market with crosslinking degrees of 3%, 4%, and 10%. GF levels were measured using sandwich ELISA method based on the protocol provided by anti-TGF-β1, platelet-derived growth factor (PDGF), and basic fibroblast growth factor (bFGF) antibody producers (Cloud-Clone Corp®, Texas, USA).

RESULTS:

Low degree HA crosslinking (3% and 4%) elevated TGF-β1 release in WJSCs-CM. HA crosslinking did not provoke increased levels of PDGF and bFGF in WJSCs-CM, both at low and higher degrees.

CONCLUSION:

Low degree HA crosslinking induced the increase of TGF-β1 release in WJSCs-CM.

α-Ionone Protects Against UVB-Induced Photoaging in Human Dermal Fibroblasts

Ultraviolet (UV) light-induced wrinkle formation is a major dermatological problem and is associated with alteration in collagen. Here, we investigated the potential of α-ionone, a naturally occurring aromatic compound, in regulation of UVB-induced photoaging in human Hs68 dermal fibroblasts and identified the mechanisms involved. We found that in human dermal fibroblasts, α-ionone inhibited UVB-induced loss of collagen. α-Ionone upregulated the molecules participating in the TGF-β–SMAD pathway (TGF-β1, phospho-SMAD2/3, Col1A1, and Col1A2), but downregulated the molecules involved in the MAPK–AP-1 signaling pathway (phospho-p38, phospho-JNK, phospho-ERK, phospho-c-Fos, phospho-c-Jun, MMP1, MMP3, and MMP9), in human dermal fibroblasts. α-Ionone treatment also increased hyaluronic acid contents, and this effect was accompanied by an upregulation of mRNA expression of genes (HAS1 and HAS2) involved in hyaluronic acid synthesis. Thus, α-ionone is effective in the prevention of UVB-induced decrease of collagen and hyaluronic acid in human dermal fibroblasts. We propose that α-ionone may prove beneficial for the prevention of UV-induced wrinkle formation and skin damage.

Natural Selection Equally Supports the Human Tendencies in Subordination and Domination: A Genome-Wide Study With in silico Confirmation and in vivo Validation in Mice

We proposed the following heuristic decision-making rule: "IF {an excess of a protein relating to the nervous system is an experimentally known physiological marker of low pain sensitivity, fast postinjury recovery, or aggressive, risk/novelty-seeking, anesthetic-like, or similar agonistic-intolerant behavior} AND IF {a single nucleotide polymorphism (SNP) causes overexpression of the gene encoding this protein} THEN {this SNP can be a SNP marker of the tendency in dominance} WHILE {underexpression corresponds to subordination} AND vice versa." Using this decision-making rule, we analyzed 231 human genes of neuropeptidergic, non-neuropeptidergic, and neurotrophinergic systems that encode neurotrophic and growth factors, interleukins, neurotransmitters, receptors, transporters, and enzymes. These proteins are known as key factors of human social behavior. We analyzed all the 5,052 SNPs within the 70 bp promoter region upstream of the position where the protein-coding transcript starts, which were retrieved from databases Ensembl and dbSNP using our previously created public Web service SNP_TATA_Comparator (http://beehive.bionet.nsc.ru/cgi-bin/mgs/tatascan/start.pl). This definition of the promoter region includes all TATA-binding protein (TBP)-binding sites. A total of 556 and 552 candidate SNP markers contributing to the dominance and the subordination, respectively, were uncovered. On this basis, we determined that 231 human genes under study are subject to natural selection against underexpression (significance p < 0.0005), which equally supports the human tendencies in domination and subordination such as the norm of a reaction (plasticity) of the human social hierarchy. These findings explain vertical transmission of domination and subordination traits previously observed in rodent models. Thus, the results of this study equally support both sides of the century-old unsettled scientific debate on whether both aggressiveness and the social hierarchy among humans are inherited (as suggested by Freud and Lorenz) or are due to non-genetic social education, when the children are influenced by older individuals across generations (as proposed by Berkowitz and Fromm).

Vascular endothelial Cdc42 deficiency delays skin wound-healing processes by increasing IL-1β and TNF-α expression

Angiogenesis is an important step in skin wound repair. Angiogenesis is affected by the functions of many types of cells, especially endothelial cells. Cdc42 plays a vital role in endothelial cell function and vascular development; however, the role of Cdc42 in skin microvascular permeability and skin wound healing is unclear. This study investigated the involvement of Cdc42 in skin wound-healing processes based on its known roles in angiogenesis. Full-thickness skin wounds were created on wild-type and inducible vascular-endothelial-specific Cdc42^-/- mice. Cdc42 deletion in endothelium affected wound healing in following ways. Reepithelialization of wounds in Cdc42^-/- mice was delayed compared with that of wounds in wild-type mice. The degree of angiogenesis of wound granulation tissue was significantly lower in Cdc42^-/- mice than in wild-type mice. Infiltration of F4/80+ macrophages and the expression of MCP-1, IL-1β, and TNF-α were increased in the wound bed of Cdc42^-/- mice compared with wild-type mice. These results confirm that Cdc42 in endothelium is required for angiogenesis and is an essential regulator of key skin wound-healing processes.

The increase of interfollicular epidermal stem cells and regulation of aryl hydrocarbon receptor and its repressors in the skin through hydroporation with anti-aging cocktail

BACKGROUNDS

Hydroporation is a procedure that involves a subsonic flow of air and microdroplets into the skin. We previously reported that hydroporation treatment with a cocktail solution containing copper-glycyl-L-histidyl-L-lysyl, oligo hyaluronic acid, rhodiola extract, tranexamic acid, and β-glucan yielded positive effects on skin aging.

OBJECTIVES

The aim of this study was to evaluate the effects of hydroporation with anti-aging cocktail on interfollicular epidermal stem cells (IFESCs) and expression of aryl hydrocarbon receptor (AhR)/AhR repressor (AhRR) in the skin.

METHODS

Skin samples from six volunteers who were treated with hydroporation were analyzed via confocal microscopic examination.

RESULTS

Markers for dermal matrix (procollagen type I and fibrillin-1) and basement membrane (type IV collagen and integrin α6) were increased after treatment. Moreover, there was a significant increase in the expression level of histone deacetylase 1-positive/p63-negative basal cells, which we previously reported as interfollicular epidermal stem cells. The expression level of AhR was significantly decreased, whereas that of AhRR was increased. This indicates an alteration in the interaction between the skin and environment posttreatment.

CONCLUSION

Anti-aging hydroporation treatment recovered the stem cell potential of basal cells. Moreover, this treatment decreased AhR and increased AhRR in the skin, which may protect the skin from the harmful environment.

Scar management in burn injuries using drug delivery and molecular signaling: Current treatments and future directions

In recent decades, there have been tremendous improvements in burn care that have allowed patients to survive severe burn injuries that were once fatal. However, a major limitation of burn care currently is the development of hypertrophic scars in approximately 70% of patients. This significantly decreases the quality of life for patients due to the physical and psychosocial symptoms associated with scarring. Current approaches to manage scarring include surgical techniques and non-surgical methods such as laser therapy, steroid injections, and compression therapy. These treatments are limited in their effectiveness and regularly fail to manage symptoms. As a result, the development of novel treatments that aim to improve outcomes and quality of life is imperative. Drug delivery that targets the molecular cascades of wound healing to attenuate or prevent hypertrophic scarring is a promising approach that has therapeutic potential. In this review, we discuss current treatments for scar management after burn injury, and how drug delivery targeting molecular signaling can lead to new therapeutic strategies.

Invariant NKT cells promote skin wound healing by preventing a prolonged neutrophilic inflammatory response

The wound-healing process consists of the inflammation, proliferation, and remodeling phases. In chronic wounds, the inflammation phase is prolonged with persistent neutrophil infiltration. The inflammatory response is critically regulated by cytokines and chemokines that are secreted from various immune cells. Recently, we showed that skin wound healing was delayed and the healing process was impaired under conditions lacking invariant natural killer T (iNKT) cells, an innate immune lymphocyte with potent immuno-regulatory activity. In the present study, we investigated the effect of iNKT cell deficiency on the neutrophilic inflammatory response during the wound healing process. Neutrophil infiltration was prolonged in wound tissue in mice genetically lacking iNKT cells (Jα18KO mice) than in wild-type (WT) control mice on days 1 and 3 after wounding. MIP-2, KC, and IL-17A were produced at a significantly higher level in Jα18KO mice than in WT mice. In addition, neutrophil apoptosis was significantly reduced in the wound tissue in Jα18KO mice than in WT mice. Treatment with anti-IL-17A mAb, anti-Gr-1 mAb, or neutrophil elastase inhibitor reversed the impaired wound healing in Jα18KO mice. These results suggest that iNKT cells may promote the wound healing process through preventing the prolonged inflammatory response mediated by neutrophils.

Transcriptomic responses to wounding: meta-analysis of gene expression microarray data

BACKGROUND

A vast amount of microarray data on transcriptomic response to injury has been collected so far. We designed the analysis in order to identify the genes displaying significant changes in expression after wounding in different organisms and tissues. This meta-analysis is the first study to compare gene expression profiles in response to wounding in as different tissues as heart, liver, skin, bones, and spinal cord, and species, including rat, mouse and human.

RESULTS

We collected available microarray transcriptomic profiles obtained from different tissue injury experiments and selected the genes showing a minimum twofold change in expression in response to wounding in prevailing number of experiments for each of five wound healing stages we distinguished: haemostasis & early inflammation, inflammation, early repair, late repair and remodelling. During the initial phases after wounding, haemostasis & early inflammation and inflammation, the transcriptomic responses showed little consistency between different tissues and experiments. For the later phases, wound repair and remodelling, we identified a number of genes displaying similar transcriptional responses in all examined tissues. As revealed by ontological analyses, activation of certain pathways was rather specific for selected phases of wound healing, such as e.g. responses to vitamin D pronounced during inflammation. Conversely, we observed induction of genes encoding inflammatory agents and extracellular matrix proteins in all wound healing phases. Further, we selected several genes differentially upregulated throughout different stages of wound response, including established factors of wound healing in addition to those previously unreported  in this context such as PTPRC and AQP4.

CONCLUSIONS

We found that transcriptomic responses to wounding showed similar traits in a diverse selection of tissues including skin, muscles, internal organs and nervous system. Notably, we distinguished transcriptional induction of inflammatory genes not only in the initial response to wounding, but also later, during wound repair and tissue remodelling.

MicroRNAs in the skin: role in development, homoeostasis and regeneration

The skin is the largest organ of the integumentary system and possesses a vast number of functions. Due to the distinct layers of the skin and the variety of cells which populate each, a tightly regulated network of molecular signals control development and regeneration, whether due to programmed cell termination or injury. MicroRNAs (miRs) are a relatively recent discovery; they are a class of small non-coding RNAs which possess a multitude of biological functions due to their ability to regulate gene expression via post-transcriptional gene silencing. Of interest, is that a plethora of data demonstrates that a number of miRs are highly expressed within the skin, and are evidently key regulators of numerous vital processes to maintain non-aberrant functioning. Recently, miRs have been targeted as therapeutic interventions due to the ability of synthetic 'antagomiRs' to down-regulate abnormal miR expression, thereby potentiating wound healing and attenuating fibrotic processes which can contribute to disease such as systemic sclerosis (SSc). This review will provide an introduction to the structure and function of the skin and miR biogenesis, before summarizing the literature pertaining to the role of miRs. Finally, miR therapies will also be discussed, highlighting important future areas of research.

TGF-β, Bone Morphogenetic Protein, and Activin Signaling and the Tumor Microenvironment

The cellular and noncellular components surrounding the tumor cells influence many aspects of tumor progression. Transforming growth factor β (TGF-β), bone morphogenetic proteins (BMPs), and activins have been shown to regulate the phenotype and functions of the microenvironment and are attractive targets to attenuate protumorigenic microenvironmental changes. Given the pleiotropic nature of the cytokines involved, a full understanding of their effects on numerous cell types in many contexts is necessary for proper clinical intervention. In this review, we will explore the various effects of TGF-β, BMP, and activin signaling on stromal phenotypes known to associate with cancer progression. We will summarize these findings in the context of their tumor suppressive or promoting effects, as well as the molecular changes that these cytokines induce to influence stromal phenotypes.

TAZ contributes to pulmonary fibrosis by activating profibrotic functions of lung fibroblasts

Transcriptional coactivator with PDZ-binding motif (TAZ) regulates a variety of biological processes. Nuclear translocation and activation of TAZ are regulated by multiple mechanisms, including actin cytoskeleton and mechanical forces. TAZ is involved in lung alveolarization during lung development and Taz-heterozygous mice are resistant to bleomycin-induced lung fibrosis. In this study, we explored the roles of TAZ in the pathogenesis of idiopathic pulmonary fibrosis (IPF) through histological analyses of human lung tissues and cell culture experiments. TAZ was highly expressed in the fibroblastic foci of lungs from patients with IPF. TAZ controlled myofibroblast marker expression, proliferation, migration, and matrix contraction in cultured lung fibroblasts. Importantly, actin stress fibers and nuclear accumulation of TAZ were more evident when cultured on a stiff matrix, suggesting a feedback mechanism to accelerate fibrotic responses. Gene expression profiling revealed TAZ-mediated regulation of connective tissue growth factor (CTGF) and type I collagen. Clinical relevance of TAZ-regulated gene signature was further assessed using publicly available transcriptome data. These findings suggest that TAZ is involved in the pathogenesis of IPF through multifaceted effects on lung fibroblasts.

ILK-PI3K/AKT pathway participates in cutaneous wound contraction by regulating fibroblast migration and differentiation to myofibroblast

The interactions between fibroblasts and the extracellular matrix in wound contraction are mainly mediated via integrin signaling. Integrin-linked kinase (ILK) is a key mediator in integrin signal transduction. We investigated the role of ILK in cutaneous wound contraction. We found that ILK was involved in cutaneous wound healing in rats, and ILK and PI3K/AKT inhibitors inhibited wound contraction and re-epithelialization, consequently delaying wound healing in vivo. Further, using in vitro studies, we demonstrated that ILK and PI3K/AKT inhibitors suppressed the contraction of fibroblast-populated collagen lattices, inhibited fibroblast migration, and interrupted the effect of TGF-β1 on promoting alpha smooth muscle actin (α-SMA) expression in fibroblasts. When ILK expression was directly blocked by ILK small interfering RNA transfection, the migration and α-SMA expression of normal dermal fibroblasts were significantly suppressed as well. The data suggest that the ILK-PI3K/AKT signaling pathway mediates cutaneous wound contraction by regulating fibroblast migration and differentiation to myofibroblasts.

Myofibroblasts contribute to but are not necessary for wound contraction

Wound contraction facilitates tissue repair. The correct balance between too little contraction, which leads to non-healing wounds, and too much contraction, which leads to contractures, is important for optimal healing. Thus, understanding which cells cause wound contraction is necessary to optimize repair. Wound contraction is hypothesized to develop from myofibroblast (cells which express alpha-smooth muscle actin; ACTA2) contractility, while the role of fibroblast contractility is unknown. In this study, we utilized ACTA2 null mice to determine what role fibroblasts play in wound contraction. Human scar contractures were immunostained for ACTA2, beta-cytoplasmic actin (ACTB), and gamma-cytoplasmic actin (ACTG1). Full-thickness cutaneous wounds were created on dorsum of ACTA2(+/+) mice and strain-matching ACTA2(+/-) and ACTA2(-/-) mice. Wound contraction was quantified. Tissue was harvested for histologic, immunohistochemical and protein analysis. Compared with surrounding unwounded skin, human scar tissue showed increased expression of ACTA2, ACTB, and ACTG1. ACTA2 was focally expressed in clusters. ACTB and ACTG1 were widely, highly expressed throughout scar tissue. Wound contraction was significantly retarded in ACTA2(-/-) mice, as compared to ACTA2(+/+) controls. Control mice had increased epithelialization, cell proliferation, and neovascularization. ACTA2(-/-) mice had lower levels of apoptosis, and fewer total numbers of cells. Smaller amount of collagen deposition and immature collagen organization in ACTA2(-/-) mice demonstrate that wounds were more immature. These data demonstrate that myofibroblasts contribute to but are not necessary for wound contraction. Mechanisms by which fibroblasts promote wound contraction may include activation of contractile signaling pathways, which promote interaction between non-muscle myosin II and ACTB and ACTG1.

Nucleolin enhances the proliferation and migration of heat-denatured human dermal fibroblasts

Denatured dermis, a part of dermis in burned skin, has the ability to restore its normal morphology and functions after their surrounding microenvironment is improved. However, the cellular and molecular mechanisms by which the denatured dermis could improve wound healing are still unclear. This study aimed to investigate the role of nucleolin during the recovery of heat-denatured human dermal fibroblasts. Nucleolin mRNA and protein expression were significantly increased time-dependently during the recovery of heat-denatured human dermal fibroblasts (52 °C, 30 seconds). Heat-denaturation promoted a time-dependent cell proliferation, migration, chemotaxis, and scratched wound healing during the recovery of human dermal fibroblasts. These effects were prevented by knockdown of nucleolin expression with small interference RNA (siRNA), whereas overexpression of nucleolin enhanced cell proliferation, migration, and chemotaxis of human dermal fibroblasts with heat-denaturation. In addition, the expression of transforming growth factor-beta 1(TGF-β1) was significantly increased during the recovery of heat-denatured dermis and human dermal fibroblasts. TGF-β1 expression was up-regulated by nucleolin in human dermal fibroblasts. The results suggest that nucleolin expression is up-regulated, and play an important role in promoting cell proliferation, migration, and chemotaxis of human dermal fibroblasts during the recovery of heat-denatured dermis with a mechanism probably related to TGF-β1.

Cross-talk between TGF-β/Smad pathway and Wnt/β-catenin pathway in pathological scar formation

TGF-β1 is a key factor in the process of wound healing, which is regulated by TGF-β/Smad pathway. We previously demonstrated that TGF-β1 contributed to pathological scar formation. And previous studies also suggested Wnt/β-catenin pathway might be involved in wound healing. However, their role and relation in pathological scar formation remains not very clear. For evaluating TGF-β1 and β-catenin, key factors of the two signal pathways, immunohistochemistry, western blot analysis and RT-PCR were used. Simultaneously, immunohistochemistry were used to evaluate Smad2, Smad3 and Wnt-1, which were also the important factors. We found that they all significantly accumulated in pathological scars compared with normal skins (P<0.05), that implied the two signal pathways both contributed to pathological scar formation. Meanwhile, β-catenin expression showed a tendency to increase first and then decrease under the influence of different concentrations of TGF-β1 (P<0.01). It is possible that there is a complicated interaction between the two signal pathways in pathological scar formation (both synergy and antagonism).

Reduced granulation tissue and wound strength in the absence of α11β1 integrin

Previous wound healing studies have failed to define a role for either α1β1 or α2β1 integrin in fibroblast-mediated wound contraction, suggesting the involvement of another collagen receptor in this process. Our previous work demonstrated that the integrin subunit α11 is highly induced during wound healing both at the mRNA and protein level, prompting us to investigate and dissect the role of the integrin α11β1 during this process. Therefore, we used mice with a global ablation of either α2 or α11 or both integrin subunits and investigated the repair of excisional wounds. Analyses of wounds demonstrated that α11β1 deficiency results in reduced granulation tissue formation and impaired wound contraction, independently of the presence of α2β1. Our combined in vivo and in vitro data further demonstrate that dermal fibroblasts lacking α11β1 are unable to efficiently convert to myofibroblasts, resulting in scar tissue with compromised tensile strength. Moreover, we suggest that the reduced stability of the scar is a consequence of poor collagen remodeling in α11^−/− wounds associated with defective transforming growth factor-β–dependent JNK signaling.

Inflammation and pyroptosis mediate muscle expansion in an interleukin-1β (IL-1β)-dependent manner

Muscle inflammation is often associated with its expansion. Bladder smooth muscle inflammation-induced cell death is accompanied by hyperplasia and hypertrophy as the primary cause for poor bladder function. In mice, DNA damage initiated by chemotherapeutic drug cyclophosphamide activated caspase 1 through the formation of the NLRP3 complex resulting in detrusor hyperplasia. A cyclophosphamide metabolite, acrolein, caused global DNA methylation and accumulation of DNA damage in a mouse model of bladder inflammation and in cultured bladder muscle cells. In correlation, global DNA methylation and NLRP3 expression was up-regulated in human chronic bladder inflammatory tissues. The epigenetic silencing of DNA damage repair gene, Ogg1, could be reversed by the use of demethylating agents. In mice, demethylating agents reversed cyclophosphamide-induced bladder inflammation and detrusor expansion. The transgenic knock-out of Ogg1 in as few as 10% of the detrusor cells tripled the proliferation of the remaining wild type counterparts in an in vitro co-culture titration experiment. Antagonizing IL-1β with Anakinra, a rheumatoid arthritis therapeutic, prevented detrusor proliferation in conditioned media experiments as well as in a mouse model of bladder inflammation. Radiation treatment validated the role of DNA damage in the NLRP3-associated caspase 1-mediated IL-1β secretory phenotype. A protein array analysis identified IGF1 to be downstream of IL-1β signaling. IL-1β-induced detrusor proliferation and hypertrophy could be reversed with the use of Anakinra as well as an IGF1 neutralizing antibody. IL-1β antagonists in current clinical practice can exploit the revealed mechanism for DNA damage-mediated muscular expansion.

Expression of transforming growth factor-β after different non-invasive facial rejuvenation modalities

BACKGROUND

Transforming growth factor-β (TGF-β) is a major regulator of the synthesis of extracellular matrix (ECM) proteins in human skin as it stimulates fibroblast proliferation and collagen production. Perturbed TGF-β expression may play a key role in the pathogenesis of skin aging.

OBJECTIVES

This study was conducted to objectively evaluate the effects of different modalities of non-invasive facial rejuvenation on TGF-β expression and to correlate its level with that of newly synthesized collagen.

METHODS

A total of 36 patients with Fitzpatrick skin types III and IV were divided into six groups. Each group of six patients was subjected to a different non-invasive modality for the treatment of skin aging, including radiofrequency (RF), Nd:YAG 1320-nm laser and Er:YAG 2940-nm laser mini-peels, intense pulsed light (IPL), mesotherapy injection, and electro-optical synergy (ELOS). Skin biopsies were obtained before treatment, at the end of treatment, and at three months post-treatment. In addition, biopsies were obtained from 30 control subjects. Levels of TGF-β were quantitatively evaluated using computerized image analysis of immunostained sections.

RESULTS

The expression of TGF-β was statistically significantly increased (P < 0.05) at the end of Nd:YAG 1320-nm and Er:YAG 2940-nm mini-peel treatments compared with baseline levels, and at three months post-treatment with RF and ELOS compared with pretreatment and end-of-treatment levels. However, no significant differences (P > 0.05) were observed in TGF-β level in response to IPL or mesotherapy treatments in comparison with baseline. The level of TGF-β was positively correlated (P < 0.05) to that of newly synthesized collagen at the end of Nd:YAG 1320-nm laser and Er:YAG 2940-nm laser mini-peels, as well as at three months after RF and ELOS treatments.

CONCLUSIONS

Radiofrequency, ELOS, and Nd:YAG 1320-nm laser and Er:YAG 2940-nm laser mini-peels resulted in an increase in TGF-β expression, which may mediate the effects of these modalities in enhancing dermal collagen expression through the activation of fibroblasts and thereby reverse the photoaging of skin.

Analysis of morphological characteristics and expression levels of extracellular matrix proteins in skin wounds to determine wound age in living subjects in forensic medicine

OBJECTIVE

Wound age determination in living subjects is important in routine diagnostics in forensic medicine. Macroscopical description of a wound to determine wound age however is inadequate. The aim of this study was to assess whether it would be feasible to determine wound age via analysis of morphological characteristics and extracellular matrix proteins in skin biopsies of living subjects referred to a forensic outpatient clinic.

METHODS

Skin biopsies (n=101), representing the border area of the wound, were taken from skin injuries of known wound age (range: 4.5h-25 days) in living subjects. All biopsies were analyzed for 3 morphological features (ulceration, parakeratosis and hemorrhage) and 3 extracellular matrix markers (collagen III, collagen IV and α-SMA). For quantification, biopsies were subdivided in 4 different timeframes: 0.2-2 days, 2-4 days, 4-10 days and 10-25 days old wounds. Subsequently, a probability scoring system was developed.

RESULTS

For hemorrhage, collagen III, collagen IV and α-SMA expression no relation with wound age was found. Ulceration was only found in wounds of 0.2-2, 2-4 and 4-10 days old, implying that the probability that a wound was more than 10 days old in case of ulceration is equal to 0%. Also parakeratosis was almost exclusively found in wounds of 0.2-2, 2-4 and 4-10 days old, except for one case with a wound age of 15 days old. The probability scoring system of all analyzed markers, as depicted above, however can be used to calculate individual wound age probabilities in biopsies of skin wounds of living subjects.

CONCLUSIONS

We have developed a probability scoring system, analysing morphological characteristics and extracellular matrix proteins in superficial skin biopsies of wounds in living subjects that can be applied in forensic medicine for wound age determination.

CCN2 expression by fibroblasts is not required for cutaneous tissue repair

The CCN family of matricellular proteins, which includes CCN2 and CCN1, is believed to have a major in vivo role in controlling tissue morphogenesis and repair. In adult skin, the proadhesive matricellular protein connective tissue growth factor (CTGF/CCN2) is specifically up-regulated in fibrosis and wound healing. In mice, CCN2 is required for dermal fibrogenesis, but whether CCN2 is required for cutaneous tissue repair is unknown. To address this question, in this report we subjected adult mice bearing a fibroblast-specific deletion of CCN2 to the dermal punch model of cutaneous tissue repair. Loss of CCN2 did not appreciably affect the kinetics of tissue repair, collagen content, or the number of α-smooth muscle actin-positive cells. CCN1 (cyr61), which has in vitro effect similar to CCN2, is also induced in cutaneous tissue repair. Fibroblast-specific CCN1/CCN2 double knockout mice were also generated; loss of both CCN1 and CCN2 together did not appreciably affect cutaneous tissue repair. However, loss of CCN2 resulted in impaired recruitment of NG2-positive pericyte-like cells to the wound area. Collectively, these results indicate that neither CCN2 nor CCN1 is essential for cutaneous tissue repair; CCN2 appears to be required for recruitment of pericyte-like cells and may represent a specific antifibrotic target.

FOXO1, TGF-β regulation and wound healing

Re-epithelialization is a complex process that involves migration and proliferation of keratinocytes, in addition to the production of cytokines and growth factors that affect other cells. The induction of transcription factors during these processes is crucial for successful wound healing. The transcription factor forkhead boxO-1 (FOXO1) has recently been found to be an important regulator of wound healing. In particular, FOXO1 has significant effects through regulation of transforming growth factor-beta (TGF-β) expression and protecting keratinocytes from oxidative stress. In the absence of FOXO1, there is increased oxidative damage, reduced TGF-β1 expression, reduced migration and proliferation of keratinocytes and increased keratinocytes apoptosis leading to impaired re-epithelialization of wounds.

Response of human skin to esthetic scarification

This study was undertaken to investigate changes in RNA expression in previously healthy adult human skin following thermal injury induced by contact with hot metal that was undertaken as part of esthetic scarification, a body modification practice. Subjects were recruited to have pre-injury skin and serial wound biopsies performed. 4 mm punch biopsies were taken prior to branding and 1 h, 1 week, and 1, 2 and 3 months after injury. RNA was extracted and quality assured prior to the use of a whole-genome based bead array platform to describe expression changes in the samples using the pre-injury skin as a comparator. Analysis of the array data was performed using k-means clustering and a hypergeometric probability distribution without replacement and corrections for multiple comparisons were done. Confirmatory q-PCR was performed. Using a k of 10, several clusters of genes were shown to co-cluster together based on Gene Ontology classification with probabilities unlikely to occur by chance alone. OF particular interest were clusters relating to cell cycle, proteinaceous extracellular matrix and keratinization. Given the consistent expression changes at 1 week following injury in the cell cycle cluster, there is an opportunity to intervene early following burn injury to influence scar development.

Oestrogen receptor-alpha and -beta expression in breast implant capsules: experimental findings and clinical correlates

Myofibroblasts provide a force to decrease the surface area of breast implant capsules as the collagen matrix matures. 17-β-Oestradiol promotes myofibroblast differentiation and contraction. The aim of the study was to investigate the expression of oestrogen receptors α and β in capsular tissue. The study enrolled 70 women (80 capsules) who underwent expander or implant removal, following breast reconstruction. Specimens were stained with haematoxylin/eosin, Masson trichrome and immunohistochemistry and immunofluorescence stainings for alpha-smooth muscle actin (α-SMA), oestrogen receptor-alpha (ER-α) and oestrogen receptor-beta (ER-β). The relationship between anti-oestrogenic therapy and capsular severity was evaluated. A retrospective analysis of 233 cases of breast reconstruction was conducted. Myofibroblasts expressed ER-α, ER-β or both. In the whole sample, α-SMA score positively correlated with ER-α (p = 0.022) and ER-β expression (p < 0.004). ER-β expression negatively correlated with capsular thickness (p < 0.019). In capsules surrounding expanders α-SMA and ER-α, expressions negatively correlated with time from implantation (p = 0.002 and p = 0.016, respectively). The incidence of grade III-IV contracture was higher in patients who did not have anti-oestrogenic therapy (p < 0.036); retrospective analysis of 233 cases confirmed this finding (p < 0.0001). This study demonstrates the expression of oestrogen receptors in myofibroblasts of capsular tissue. A lower contracture severity was found in patients who underwent anti-oestrogenic therapy.

A reciprocal role of prostate cancer on stromal DNA damage

DNA damage found in prostate cancer-associated fibroblasts (CAF) promotes tumor progression. In the absence of somatic mutations in CAF, epigenetic changes dictate how stromal coevolution is mediated in tumors. Seventy percent of prostate cancer patients lose expression of transforming growth factor-beta type II receptor (TGFBR2) in the stromal compartment (n=77, P-value=0.0001), similar to the rate of glutathione S-transferase P1 (GSTP1) silencing. Xenografting of human prostate cancer epithelia, LNCaP, resulted in the epigenetic Tgfbr2 silencing of host mouse prostatic fibroblasts. Stromal Tgfbr2 promoter hypermethylation, initiated by LNCaP cells, was found to be dependent on interleukin 6 expression, based on neutralizing antibody studies. We further found that pharmacologic and transgenic knockout of TGF-β responsiveness in prostatic fibroblasts induced Gstp1 promoter methylation. It is known that TGF-β promotes DNA stability, however, the mechanism is not well understood. Both prostatic human CAF and mouse transgenic knockout of Tgbr2 had elevated DNA methyltransferase I (DNMT1) activity and histone H3 lysine 9 trimethylation (H3K9me3) to suggest greater promoter methylation. Interestingly, the conditional knockout of Tgfbr2 in mouse prostatic fibroblasts, in modeling epigenetic silencing of Tgfbr2, had greater epigenetic gene silencing of multiple DNA damage repair and oxidative stress response genes, based on promoter methylation array analysis. Homologous gene silencing was validated by reverse transcriptase (RT)-PCR in mouse and human prostatic CAF. Not surprisingly, DNA damage repair gene silencing in the prostatic stromal cells corresponded with the presence of DNA damage. Restoring the expression of the epigenetically silenced genes in wild-type fibroblasts with radiation-induced DNA damage reduced tumor progression. Tumor progression was inhibited even when epigenetic silencing was reversed in the Tgfbr2-knockout prostatic fibroblasts. Taken together, fibroblastic epigenetic changes causative of DNA damage, initiated by association with cancer epithelia, is a dominant mediator of tumor progression over TGF-β responsiveness.

Calponin 3 regulates stress fiber formation in dermal fibroblasts during wound healing

Skin wound healing is an intricate process involving various cell types and molecules. In granulation tissue, fibroblasts proliferate and differentiate into myofibroblasts and generate mechanical tension for wound closure and contraction. Actin stress fibers formed in these cells, especially those containing α-smooth muscle actin (α-SMA), are the central machinery for contractile force generation. In the present study, calponin 3 (CNN3), which has a phosphorylation-dependent actin-binding property, was identified in the molecular mechanism underlying stress fiber formation. CNN3 was expressed by fibroblasts/myofibroblasts in the proliferation phase of wound healing, and was associated with α-SMA in stress fibers formed by cultured dermal fibroblasts. CNN3 expression was post-transcriptionally regulated by tension, as demonstrated by disruption of actin filament organization under floating culture or blebbistatin treatment. CNN3 knockdown in primary fibroblasts impaired stress fiber formation, resulting in a phenotype of decreased cellular dynamics such as cell motility and contractile ability. These findings indicate that CNN3 participates in actin stress fiber remodeling, which is required for cell motility and contraction of dermal fibroblasts in the wound healing process.

Integrins as Modulators of Transforming Growth Factor Beta Signaling in Dermal Fibroblasts During Skin Regeneration After Injury

SIGNIFICANCE

Abnormal wound repair results from disorders in granulation tissue remodeling, and can lead to hypertrophic scarring and fibrosis. Excessive scarring can compromise tissue function and decrease tissue resistance to additional injuries. The development of potential therapies to minimize scarring is, thus, necessary to address an important clinical problem.

RECENT ADVANCES

It has been clearly established that multiple cytokines and growth factors participate in the regulation of cutaneous wound healing. More recently, it has become apparent that these factors do not necessarily activate isolated signaling pathways. Rather, in some cases, there is cross-modulation of several cellular pathways involved in this process. Two of the key pathways that modulate each other during wound healing are activated by transforming growth factor-β and by extracellular matrix proteins acting through integrins.

CRITICAL ISSUES

The pathogenesis of excessive scarring upon wound healing is not fully understood, as a result of the complexity of this process. However, the fact that many pathways combine to produce fibrosis provides multiple potential therapeutic targets. Some of them have been identified, such as focal adhesion kinase and integrin-linked kinase. Currently, a major challenge is to develop pharmacological inhibitors of these proteins with therapeutic value to promote efficient wound repair.

FUTURE DIRECTIONS

The ability to better understand how different pathways crosstalk during wound repair and to identify and pharmacologically modulate key factors that contribute to the regulation of multiple wound-healing pathways could potentially provide effective therapeutic targets to decrease or prevent excessive scar formation and/or development of fibrosis.

Transforming Growth Factor Beta Signaling in Cutaneous Wound Healing: Lessons Learned from Animal Studies

SIGNIFICANCE

Wound healing is a complex physiological process involving a multitude of growth factors, among which transforming growth factor beta (TGF-β) has the broadest spectrum of effects. Animal studies have provided key information on the mechanisms of TGF-β action in wound healing and have guided the development of therapeutic strategies targeting the TGF-β pathway to improve wound healing and scarring outcome.

RECENT ADVANCES

Development of tissue-specific expression systems for overexpression or knockout of TGF-β signaling pathway components has led to novel insight into the role of TGF-β signaling in wound healing. This work has also identified molecules that might serve as molecular targets for the treatment of pathological skin conditions such as chronic wounds and excessive scarring (fibrosis).

CRITICAL ISSUES

Many of the mouse models with genetic alterations in the TGF-β signaling pathway develop an underlying skin abnormality, which may pose some limitations on the interpretation of wound-healing results obtained in these animals. Also, TGF-β's pleiotropic effects on many cell types throughout all phases of wound healing present a challenge in designing specific strategies for targeting the TGF-β signaling pathway to promote wound healing or reduce scarring.

FUTURE DIRECTIONS

Further characterization of TGF-β signaling pathway components using inducible tissue-specific overexpression or knockout technology will be needed to corroborate results obtained in mouse models that display a skin phenotype, and to better understand the role of TGF-β signaling during distinct phases of the wound-healing process. Such studies will also provide a better understanding of how TGF-β mediates its autocrine, paracrine, and double paracrine effects on cellular responses in vivo during wound healing.