Possible involvement of mast cells in collagen remodeling in the late phase of cutaneous wound healing in mice

The evolving role of mast cells in wound healing: insights from recent research and diverse models

Chronic wounds significantly burden health care systems worldwide, requiring novel strategies to ease their impact. Many physiological processes underlying wound healing are well studied but the role of mast cells remains controversial. Mast cells are innate immune cells and play an essential role in barrier function by inducing inflammation to defend the host against chemical irritants and infections, among others. Many mast cell-derived mediators have proposed roles in wound healing; however, in vivo evidence using mouse models has produced conflicting results. Recently, studies involving more complex wound models such as infected wounds, diabetic wounds and wounds healing under psychological stress suggest that mast cells play critical roles in these processes. This review briefly summarizes the existing literature regarding mast cells in normal wounds and the potential reasons for the contradictory results. Focus will be placed on examining more recent work emerging in the last 5 years that explores mast cells in more complex systems of wound healing, including infection, psychological stress and diabetes, with a discussion of how these discoveries may inspire future work in the field.

Mast cells and ocular surface: An update review

Mast cells (MCs), traditionally viewed as key players in IgE-mediated allergic responses, are increasingly recognized for their versatile roles. Situated at critical barrier sites such as the ocular surface, these sentinel cells participate in a broad array of physiological and pathological processes. This review presents a comprehensive update on the immune pathophysiology of MCs, with a particular focus on the mechanisms underlying innate immunity. It highlights their roles at the ocular surface, emphasizing their participation in allergic reactions, maintenance of corneal homeostasis, neovascularization, wound healing, and immune responses in corneal grafts. The review also explores the potential of MCs as therapeutic targets, given their significant contributions to disease pathogenesis and their capacity to modulate immunity. Through a thorough examination of current literature, we aim to elucidate the immune pathophysiology and multifaceted roles of MCs in ocular surface health and disease, suggesting directions for future research and therapeutic innovation.

Evaluating the Healing Potential of J-Plasma Scalpel-Created Surgical Incisions in Porcine and Rat Models

Cold atmospheric plasma devices generate reactive oxygen and nitrogen species that can be anti-microbial but also promote cell migration, differentiation, and tissue wound healing. This report investigates the healing of surgical incisions created using cold plasma generated by the J-Plasma scalpel (Precise Open handpiece, Apyx Medical, Inc.) compared to a steel scalpel in in vivo porcine and rat models. The J-Plasma scalpel is currently FDA approved for the delivery of helium plasma to cut, coagulate, and ablate soft tissue during surgical procedures. To our knowledge, this device has not been studied in creating surgical incisions but only during deeper dissection and hemostasis. External macroscopic and histologic grading by blinded reviewers revealed no significant difference in wound healing appearance or physiology in incisions created using the plasma scalpel as compared with a steel blade scalpel. Incisions created with the plasma scalpel also had superior hemostasis and a reduction in tissue and blood carryover. Scanning electron microscopy (SEM) and histology showed collagen fibril fusion occurred as the plasma scalpel incised through the tissue, contributing to a sealing effect. In addition, when bacteria were injected into the dermis before incision, the plasma scalpel disrupted the bacterial membrane as visualized in SEM images. External macroscopic and histologic grading by blinded reviewers revealed no significant difference in wound healing appearance or physiology. Based on these results, we propose additional studies to clinically evaluate the use of cold plasma in applications requiring hemostasis or when an increased likelihood of subdermal pathogen leakage could cause surgical site infection (i.e., sites with increased hair follicles).

Immune cells and associated molecular markers in dermal fibrosis with focus on raised cutaneous scars

Raised dermal scars including hypertrophic, and keloid scars as well as scalp-associated fibrosing Folliculitis Keloidalis Nuchae (FKN) are a group of fibrotic raised dermal lesions that mostly occur following cutaneous injury. They are characterized by increased extracellular matrix (ECM) deposition, primarily excessive collagen type 1 production by hyperproliferative fibroblasts. The extent of ECM deposition is thought to be proportional to the severity of local skin inflammation leading to excessive fibrosis of the dermis. Due to a lack of suitable study models, therapy for raised dermal scars remains ill-defined. Immune cells and their associated markers have been strongly associated with dermal fibrosis. Therefore, modulation of the immune system and use of anti-inflammatory cytokines are of potential interest in the management of dermal fibrosis. In this review, we will discuss the importance of immune factors in the pathogenesis of raised dermal scarring. The aim here is to provide an up-to-date comprehensive review of the literature, from PubMed, Scopus, and other relevant search engines in order to describe the known immunological factors associated with raised dermal scarring. The importance of immune cells including mast cells, macrophages, lymphocytes, and relevant molecules such as cytokines, chemokines, and growth factors, antibodies, transcription factors, and other immune-associated molecules as well as tissue lymphoid aggregates identified within raised dermal scars will be presented. A growing body of evidence points to a shift from proinflammatory Th1 response to regulatory/anti-inflammatory Th2 response being associated with the development of fibrogenesis in raised dermal scarring. In summary, a better understanding of immune cells and associated molecular markers in dermal fibrosis will likely enable future development of potential immune-modulated therapeutic, diagnostic, and theranostic targets in raised dermal scarring.

Acute Inflammation in Tissue Healing

There are well-established links between acute inflammation and successful tissue repair across evolution. Innate immune reactions contribute significantly to pathogen clearance and activation of subsequent reparative events. A network of molecular and cellular regulators supports antimicrobial and tissue repair functions throughout the healing process. A delicate balance must be achieved between protection and the potential for collateral tissue damage associated with overt inflammation. In this review, we summarize the contributions of key cellular and molecular components to the acute inflammatory process and the effective and timely transition toward activation of tissue repair mechanisms. We further discuss how the disruption of inflammatory responses ultimately results in chronic non-healing injuries.

Immune Cells in Cutaneous Wound Healing: A Review of Functional Data from Animal Models

The healing of skin wounds involves the activation and recruitment of various immune cell types, many of which are believed to contribute significantly to different aspects of the repair process. Roles for immune cells have been described in practically all stages of wound healing, including hemostasis, inflammation, proliferation and scar formation/remodeling. Over the last decade, tools to deplete immune cell populations in animal models have become more advanced, leading to a surge in the number of studies examining the function of specific immune cell types in skin repair. In this review, we will summarize what is known about distinct immune cell types in cutaneous wound healing, with an emphasis on data from animal studies in which specific cell types have been targeted.

Mast-Cell Tryptase Release Contributes to Disease Progression in Lymphangioleiomyomatosis

Rationale: Lymphangioleiomyomatosis (LAM) is a multisystem disease that causes lung cysts and respiratory failure. Loss of TSC (tuberous sclerosis complex) gene function results in a clone of "LAM cells" with dysregulated mTOR (mechanistic target of rapamycin) activity. LAM cells and fibroblasts form lung nodules that also contain mast cells, although their significance is unknown. Objectives: To understand the mechanism of mast-cell accumulation and the role of mast cells in the pathogenesis of LAM. Methods: Gene expression was examined using transcriptional profiling and qRT-PCR. Mast cell/LAM nodule interactions were examined in vitro using spheroid TSC2-null cell/fibroblast cocultures and in vivo using an immunocompetent Tsc2-null murine homograft model. Measurements and Main Results: LAM-derived cell/fibroblast cocultures induced multiple CXC chemokines in fibroblasts. LAM lungs had increased tryptase-positive mast cells expressing CXCRs (CXC chemokine receptors) (P < 0.05). Mast cells located around the periphery of LAM nodules were positively associated with the rate of lung function loss (P = 0.016). LAM spheroids attracted mast cells, and this process was inhibited by pharmacologic and CRISPR/cas9 inhibition of CXCR1 and CXCR2. LAM spheroids caused mast-cell tryptase release, which induced fibroblast proliferation and increased LAM-spheroid size (1.36 ± 0.24-fold; P = 0.0019). The tryptase inhibitor APC366 and sodium cromoglycate (SCG) inhibited mast cell-induced spheroid growth. In vivo, SCG reduced mast-cell activation and Tsc2-null lung tumor burden (vehicle: 32.5.3% ± 23.6%; SCG: 5.5% ± 4.3%; P = 0.0035). Conclusions: LAM-cell/fibroblast interactions attract mast cells where tryptase release contributes to disease progression. Repurposing SCG for use in LAM should be studied as an alternative or adjunct to mTOR inhibitor therapy.

Oxidative and local histopathological response on skin wound of horses due to Amblyomma sculptum tick parasitism

Amblyomma sculptum is frequently observed parasitizing horses, responsible for economic losses, damage to the host''s skin and transmission of pathogens. The oxidative stress profile and inflammatory mechanisms involved in this parasitism remain poorly studied. Thus, this study aimed to assess the histopathological changes and oxidative profile responses of horses in the attachment site of A. sculptum to find variations that indicate resistance and susceptibility between the breeds to this tick, based on the hypothesis that resistant animals have a greater inflammatory response and lesser number of attached ticks. We analyzed female horses of two breeds, Mangalarga Marchador and Breton Postier, naturally infested by Amblyomma sculptum. The ticks were counted and full-thickness excisional skin wounds of 10 mm were made on the perineal region on the attachment site of partially engorged females for histological and biochemical analyzes. The occurrence of the tick on the skin caused an increase in cellularity, inflammatory infiltrate, mast cells, pyknotic nuclei, and changes in the fibrous components of the matrix. The negative correlation observed between tick infestation and inflammatory response indicated that animals with greater inflammatory response tend to have less tick infestation. The oxidative stress markers, MDA, PCN and NO not present great variation; however, between the antioxidant enzymes levels, SOD was higher in tick attachment of Breton Postier skin, this may mean that these animals had higher oxidative enzymatic activity and consequently less tissue damage, while the GST dropped in the attachment sites compared to the control, which may indicate that animals were in a state of significant oxidative stress or raises the question of the possibility of enzymatic sequestration by ticks. No significant differences were found in the resistance of the two breeds since most of the analyzes varied due to the presence or absence of the tick attached to the skin. We draw attention to the importance of studying characteristics of the animal's antioxidant responses to the tick and the action of tick saliva on antioxidant enzymes and ROS because these characteristics are interdependent with the inflammatory response.

Combined effects of photobiomodulation and curcumin on mast cells and wound strength in wound healing of streptozotocin-induced diabetes in rats

We investigated the probable involvement of mast cell degranulation and their numbers in the remodeling step of wound healing in a diabetic ischemic skin wound model treated with photobiomodulation plus curcumin. A total of 108 adult male Wistar rats were randomized into one healthy control and five diabetic groups. Type I diabetes was inflicted in 90 of the 108 rats. After 1 month, an excisional wound was generated in each of the 108 rats. There were one healthy group (group 1) and five diabetic groups as follows: group 2 was the untreated diabetic control group and group 3 rats were treated with sesame oil. Rats in group 4 were treated with photobiomodulation (890 nm, 890 ± 10 nm, 80 Hz, 0.2 J/cm2) and those in group 5 received curcumin dissolved in sesame oil. Group 6 rats were treated with photobiomodulation and curcumin. We conducted stereological and tensiometric tests on days 4, 7, and 15 after treatment. The results indicated that photobiomodulation significantly improved wound strength in the diabetic rats and significantly decreased the total numbers of mast cells. The diabetic control group had significantly reduced tensiometric properties of the healing wounds and a significant increase in the total numbers of mast cells. Photobiomodulation significantly improved the healing process in diabetic animals and significantly decreased the total number of mast cells. The increased numbers of mast cells in the diabetic control group negatively affected tensiometric properties of the ischemic skin wound.

Harnessing the Power of Mast Cells in unconventional Immunotherapy Strategies and Vaccine Adjuvants

Mast cells are long-lived, granular, myeloid-derived leukocytes that have significant protective and repair functions in tissues. Mast cells sense disruptions in the local microenvironment and are first responders to physical, chemical and biological insults. When activated, mast cells release growth factors, proteases, chemotactic proteins and cytokines thereby mobilizing and amplifying the reactions of the innate and adaptive immune system. Mast cells are therefore significant regulators of homeostatic functions and may be essential in microenvironmental changes during pathogen invasion and disease. During infection by helminths, bacteria and viruses, mast cells release antimicrobial factors to facilitate pathogen expulsion and eradication. Mast cell-derived proteases and growth factors protect tissues from insect/snake bites and exposure to ultraviolet radiation. Finally, mast cells release mediators that promote wound healing in the inflammatory, proliferative and remodelling stages. Since mast cells have such a powerful repertoire of functions, targeting mast cells may be an effective new strategy for immunotherapy of disease and design of novel vaccine adjuvants. In this review, we will examine how certain strategies that specifically target and activate mast cells can be used to treat and resolve infections, augment vaccines and heal wounds. Although these strategies may be protective in certain circumstances, mast cells activation may be deleterious if not carefully controlled and any therapeutic strategy using mast cell activators must be carefully explored.

A Review of the Evidence for and against a Role for Mast Cells in Cutaneous Scarring and Fibrosis

Scars are generated in mature skin as a result of the normal repair process, but the replacement of normal tissue with scar tissue can lead to biomechanical and functional deficiencies in the skin as well as psychological and social issues for patients that negatively affect quality of life. Abnormal scars, such as hypertrophic scars and keloids, and cutaneous fibrosis that develops in diseases such as systemic sclerosis and graft-versus-host disease can be even more challenging for patients. There is a large body of literature suggesting that inflammation promotes the deposition of scar tissue by fibroblasts. Mast cells represent one inflammatory cell type in particular that has been implicated in skin scarring and fibrosis. Most published studies in this area support a pro-fibrotic role for mast cells in the skin, as many mast cell-derived mediators stimulate fibroblast activity and studies generally indicate higher numbers of mast cells and/or mast cell activation in scars and fibrotic skin. However, some studies in mast cell-deficient mice have suggested that these cells may not play a critical role in cutaneous scarring/fibrosis. Here, we will review the data for and against mast cells as key regulators of skin fibrosis and discuss scientific gaps in the field.

Acidic Phospholipase A2-Peptide Derivative Modulates Oxidative Status and Microstructural Reorganization of Scar Tissue after Cutaneous Injury

From in vitro and in vivo models, the proliferative and healing potential of an acidic phospholipase A2 (LAPLA2) from Lachesis muta venom was investigated. The LAPLA2 proliferative activity was evaluated on fibroblasts and keratinocytes cultured, and the antioxidant and regenerative potential of LAPLA2 was analyzed in a murine model. The animal study consisted of four groups: C (negative control): 0.9% NaCl; SS (positive control): 1% silver sulfadiazine; L1 group: 0.5% LAPLA2; and L2 group: 0.25% LAPLA2. Wounds were topically treated daily for 12 days, and scar tissue samples were collected every 4 days. In vitro, LAPLA2 stimulated marked time-dependent cell proliferation. In vivo, it increased the antioxidant activity of superoxide dismutase (SOD) and catalase (CAT) and decreased malondialdehyde (MDA) and carbonyl protein (CP) levels in scar tissue treated with LAPLA2 at 0.5%. This peptide was effective in stimulating cellular proliferation, neoangiogenesis, type I and III collagen deposition, and maturation in a time-dependent-way, reducing the time required for wound closure. Our results indicated that LAPLA2 presented a remarkable potential in improving the oxidative status and microstructural reorganization of the scar tissue by stimulation of cellularity, angiogenesis, colagenogenesis, and wound contraction, suggesting that the peptide could be a potential candidate for a new healing drug.

IL33 and Mast Cells-The Key Regulators of Immune Responses in Gastrointestinal Cancers?

The Interleukin (IL-)1 family IL33 is best known for eliciting type 2 immune responses by stimulating mast cells (MCs), regulatory T-cells (Tregs), innate lymphoid cells (ILCs) and other immune cells. MCs and IL33 provide critical control of immunological and epithelial homeostasis in the gastrointestinal (GI) tract. Meanwhile, the role of MCs in solid malignancies appears tissue-specific with both pro and anti-tumorigenic activities. Likewise, IL33 signaling significantly shapes immune responses in the tumor microenvironment, but these effects remain often dichotomous when assessed in experimental models of cancer. Thus, the balance between tumor suppressing and tumor promoting activities of IL33 are highly context dependent, and most likely dictated by the mixture of cell types responding to IL33. Adding to this complexity is the promiscuous nature by which MCs respond to cytokines other than IL33 and release chemotactic factors that recruit immune cells into the tumor microenvironment. In this review, we integrate the outcomes of recent studies on the role of MCs and IL33 in cancer with our own observations in the GI tract. We propose a working model where the most abundant IL33 responsive immune cell type is likely to dictate an overall tumor-supporting or tumor suppressing outcome in vivo. We discuss how these opposing responses affect the therapeutic potential of targeting MC and IL33, and highlight the caveats and challenges facing our ability to effectively harness MCs and IL33 biology for anti-cancer immunotherapy.

A Comparative Study of Engineered Dermal Templates for Skin Wound Repair in a Mouse Model

Engineered dermal templates have revolutionised the repair and reconstruction of skin defects. Their interaction with the wound microenvironment and linked molecular mediators of wound repair is still not clear. This study investigated the wound bed and acellular "off the shelf" dermal template interaction in a mouse model. Full-thickness wounds in nude mice were grafted with allogenic skin, and either collagen-based or fully synthetic dermal templates. Changes in the wound bed showed significantly higher vascularisation and fibroblast infiltration in synthetic grafts when compared to collagen-based grafts (P ≤ 0.05). Greater tissue growth was associated with higher prostaglandin-endoperoxide synthase 2 (Ptgs2) RNA and cyclooxygenase-2 (COX-2) protein levels in fully synthetic grafts. Collagen-based grafts had higher levels of collagen III and matrix metallopeptidase 2. To compare the capacity to form a double layer skin substitute, both templates were seeded with human fibroblasts and keratinocytes (so-called human skin equivalent or HSE). Mice were grafted with HSEs to test permanent wound closure with no further treatment required. We found the synthetic dermal template to have a significantly greater capacity to support human epidermal cells. In conclusion, the synthetic template showed advantages over the collagen-based template in a short-term mouse model of wound repair.

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

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

The role of mast cells in pediatric gastrointestinal disease

Mast cells are granulocytes derived from CD34+ pluripotent progenitor cells that demonstrate plasticity in their development, leaving the bone marrow and differentiating in the tissue where they ultimately reside. They are best known for their role in the allergic response, but also play a prominent immunoregulatory role in other processes, including immune tolerance, the innate immune response, angiogenesis, wound healing and tissue remodeling. Mast cells are found throughout the gastrointestinal tract; their metabolic products influence and regulate intestinal epithelial and endothelial function, gastrointestinal secretion, intestinal motility and absorption, and contribute to host defense. They also play an important role in the development of visceral hypersensitivity through bidirectional interaction with the enteric nervous system. Mast cells have been found to have an increasingly important role in the pathophysiology of a number of pediatric gastrointestinal diseases. This review summarizes the current understanding of the role that mast cells play in the development of pediatric gastrointestinal disorders, including eosinophilic esophagitis, functional dyspepsia, irritable bowel syndrome, celiac disease, inflammatory bowel disease, histologically negative appendicitis, Hirschsprung’s disease, intestinal neuronal dysplasia, and food protein-induced enterocolitis syndrome.

The Cutaneous Inflammatory Response to Thermal Burn Injury in a Murine Model

Many burn interventions aim to target the inflammatory response as a means of enhancing healing or limiting hypertrophic scarring. Murine models of human burns have been developed, but the inflammatory response to injury in these models has not been well defined. The aim of this study was to profile inflammatory cell populations and gene expression relative to healing and scarring in a murine model of thermal burns. Cutaneous injuries were created on the dorsal region of C57Bl/6 mice using a heated metal rod. Animals were euthanized at selected time points over ten weeks, with the lesions evaluated using macroscopic measurements, histology, immunofluorescent histochemistry and quantitative PCR. The burn method generated a reproducible, partial-thickness injury that healed within two weeks through both contraction and re-epithelialization, in a manner similar to human burns. The injury caused an immediate increase in pro-inflammatory cytokine and chemokine expression, coinciding with an influx of neutrophils, and the disappearance of Langerhans cells and mast cells. This preceded an influx of dendritic cells and macrophages, a quarter of which displayed an inflammatory (M1) phenotype, with both populations peaking at closure. As with human burns, the residual scar increased in size, epidermal and dermal thickness, and mast cell numbers over 10 weeks, but abnormal collagen I-collagen III ratios, fibre organization and macrophage populations resolved 3–4 weeks after closure. Characterisation of the inflammatory response in this promising murine burn model will assist future studies of burn complications and aid in the preclinical testing of new anti-inflammatory and anti-scarring therapies.

Topical folinic acid enhances wound healing in rat model

PURPOSE

Folic acid is an essential vitamin participating in DNA synthesis and repair. Recently folic acid has been shown to stimulate DNA-repair capacity in dermal fibroblasts in response to injury. Thus, the present study aimed to investigate the effects of topical folinic acid, a 5-formyl derivative of tetrahydrofolic acid, on wound healing using rat wound model.

MATERIALS AND METHODS

A rat wound model was established, and the wound healing was evaluated by macroscopic and histological analyses among vehicle control, 2.5% folinic acid, 1% folinic acid, and dexpanthenol treatment groups. While an image-analysis program was used to evaluate macroscopic wound closure, connective tissue properties, mast cell numbers, and the expressions of matrix metalloproteinase 1 (MMP-1) and 9 (MMP-9) were evaluated by microscopy.

RESULTS

The 2.5% folinic acid-treated group exhibited enhanced wound healing by increased reepithelialization, neo-vessel formation, inflammatory cell migration, collagen deposition and progressive mast cell increase. Furthermore, 2.5% folinic acid induced higher expressions of MMP-1 and MMP-9.

CONCLUSIONS

Folinic acid enhances both macroscopic and microscopic wound healing in rat wound model.

Effects of Photobiomodulation on Degranulation and Number of Mast Cells and Wound Strength in Skin Wound Healing of Streptozotocin-Induced Diabetic Rats

BACKGROUND

A lack of effective treatments still exists for patients suffering from diabetes mellitus. Photobiomodulation is proved as a beneficial therapeutic modality for wounds.

OBJECTIVE

The aim of this study is to examine the effect of degranulation of mast cells and total number of mast cells in the remodeling step of an ischemic model of wound healing under the influence of photobiomodulation and conditioned medium (CM) from human bone marrow-derived mesenchymal stem cells (hBM-MSCs-CM), or CM, administered alone and or in combination.

MATERIALS AND METHODS

Initially, type 1 diabetes mellitus was induced in 72 male adult rats. Then, after a month, one incision was made on the back of each rat. Subsequently, the rats were divided into four groups. The first group was considered as the control (placebo) group, the second group received CM, the third group received photobiomodulation, and the fourth group received photobiomodulation+CM. On days 4, 7, and 15, samples were extracted from the wound for histological and tensiometric examinations. The total number of mast cells, including the three types of mast cells, was counted by the stereological methods. The tensiometric properties of the repairing tissue were examined.

RESULTS

The administration of photobiomodulation and CM, alone or in combination, significantly increased the tensiometric properties within the healing wounds. Histologically, photobiomodulation+CM, CM, and photobiomodulation groups showed a significant decrease in the three types of mast cells and in the total number of mast cells compared with the control group on day 15.

CONCLUSIONS

We conclude that photobiomodulation and CM alone and or in combination significantly accelerated the healing process in a rat with a diabetic and ischemic wound, and significantly decreased the total number of mast cells and degranulation of mast cells. We suggest that the increased number of type 2 mast cells in the control group adversely affected the tensiometric properties of wounds in this group.

Pro - inflammatory cytokines and metalloproteinase activation in polypropylene mesh implant in rat subcutaneous tissue

AIMS AND OBJECTIVES

Polypropylene meshes have been increasingly adopted for correction of pelvic organ prolapse due to its lower recurrence rate when compared to surgeries without meshes. The study of the interaction of these materials with the host tissue may contribute to the development of materials with best biocompatibility and, consequently, less complication rates.

MATERIALS AND METHODS

The present study compares the inflammatory reaction of standard-weight (SW) and lightweight (LW) meshes (72 g/m216g/m2 respectively), implanted in the abdomen of 20 adult rats, which were euthanized in four or 30 days. Quantification of pro-inflammatory markers, IL-1 and TNF-α, and of metalloproteinases, MMP2 and MMP3, were carried out through immunohistochemistry with AxioVision ® software.

RESULTS

There were no significant differences in the quantification of IL-1 and TNF-α in LW versus SW meshes. However, IL-1 quantification increased along time (30 days >4 days, p=0.0269). Also, MMP-2 quantification was similar to SW and LW and both presented a significant increase along time (30 days >4 days, p < 0.0001). MMP-3 quantification also showed no difference between the SW and LW groups, but increased along time (30 days >4 days, p=0.02).

CONCLUSIONS

Mesh's density did not influence the quantification of pro-inflammatory cytokines IL-1 and TNF-α and metalloproteinases 2 and 3. The increased expression of IL-1, MMP-2 and MMP-3 over time could represent a longstanding inflammatory response after PP mesh implantation. Possibly, the occurrence of adverse events following PP prosthetic implants can be influenced by other factors, not solely related to the amount of implanted material.

Strychnos pseudoquina modulates the morphological reorganization of the scar tissue of second intention cutaneous wounds in rats

Natural substances are used in folk medicines to treat injuries. Strychnos pseudoquina has scarring, antipyretic, and antimalarial actions. The present study aimed to analyze the effect of S. pseudoquina on cutaneous wound healing in rats. The S. pseudoquina extract was submitted to phytochemical prospection. The levels of flavonoids and total phenolic compounds in the extract were 50.7 mg/g and 2.59 mg/g, respectively. Thirty Wistar rats were individualized in cages with food and water ad libitum (registration no. 730/2014). After anesthesia, three circular wounds (12mm diameter) were made in the animals, which were randomly separated into five treatments: Sal, saline; VO, ointment vehicles (lanolin and Vaseline); SS, positive control (silver sulfadiazine 1%); LE 5, freeze-dried extract 5%; and LE 10, lyophilized extract 10%. The animals were treated with the ointment daily for 21 days. Every seven days, the area and the rate of wound contraction were evaluated. Tissue samples were removed for histopathological analysis of the number of mast cells, elastic and collagen fibers, and biochemical analyses, quantification of malondialdehyde (MDA), carbonylated proteins (PCN), superoxide dismutase (SOD), catalase (CAT), transforming growth factor β (TGF-β), Interleukin 10 (IL-10) and tumor necrosis factor (TNF). The number of mast cells, collagen and elastic fibers in the rat wounds were higher in the treatments with the plant. The extract also stimulated the activity of antioxidant enzymes, particularly SOD, presenting high levels, and maintained low levels of PCN. The TGF-β and IL-10 concentration was higher in the LE5 and LE10 treatment of the extract than in the Sal, OV and SS treatments on day 7. The ointment based on S. pseudoquina closed the wound faster and accelerated wound healing in animals.

Effect of 670 nm laser photobiomodulation on vascular density and fibroplasia in late stages of tissue repair

This study aimed to investigate the effects of gallium-aluminum-arsenium (GaAlAs) (670 nm) laser therapy on neoangiogenesis and fibroplasia during tissue remodelling. Forty male Wistar rats underwent cutaneous surgery and were divided into 2 experimental groups: the Control and Laser group (9 mW, 670 nm, 0.031 W/cm² , 4 J/cm² ). After 14, 21, 28, and 35 days, the animals were euthanised. Descriptive and quantitative analyses were performed in sections stained with haematoxylin-eosin and Sirius Red, respectively. The amounts of VEGF+ and CD31+ cells were evaluated by immunohistochemistry and histomorphometric analysis, respectively. Statistical analysis was performed using the Mann-Whitney, Friedman, and Spearman correlation test, P < 0.05. The collagen expression was significantly higher in the laser group compared with the control group on days 14 and 21 after the creation of the skin wound (P = 0.008; P = 0.016) and in the control group between 14 and 28 and 14 and 35 days (P = 0.001; P = 0.007). There were more blood vessels in three periods of the study only in the (Laser) treated group, with statistical significance at day 14 (P = 0.016). There was no statistically significant difference in VEGF+ cell count in the different experimental groups throughout the study, although a positive correlation was shown with the area of collagen on days 14 and 28 (P = 0.037). Laser treatment had a positive effect in the late course of healing, particularly with regards to collagen expression and the number of newly formed vessels. VEGF+ cells were present in both experimental groups, and VEGF appeared to influence fibroplasia in the treated group.

Attenuation of dermal wounds via downregulating oxidative stress and inflammatory markers by protocatechuic acid rich n-butanol fraction of Trianthema portulacastrum Linn. in wistar albino rats

Oxidative stress and inflammation contribute as a key factor for retarding the process of dermal wound healing. Trianthema portulcastrum Linn. (TP) leaves reported to possess antioxidant, antifungal, anti-inflammatory and antibacterial properties, which could make TP a promising wound healing agent. The current study was aimed to estimate the antioxidant potential of the fractionated hydroethanolic extract of TP leaves and evaluate wound healing activity by excision and incision wound models along with the assessment of possible underlying mechanism. Ethyl acetate, chloroform and n-butanol fractions of the hydroethanolic extract of TP leaves were examined for in vitro antioxidant ability by DPPH method. Strongest antioxidant activity bearing n-butanol fraction (nBuTP) was further analyzed quantitatively by High Performance Liquid Chromatography coupled with Diode Array Detector (HPLC-DAD). Wound healing potential of nBUTP using excision and incision wound model was studied. Wistar albino rats were randomly divided into four groups, containing six animals in each group; group I served as control treated with simple ointment base, group II was standard group, treated with povidone-iodine ointment USP (5%), group III treated with nBuTP 5% w/w ointment, and group IV treated with nBuTP 10%w/w ointment. All the groups were topically applied their respective ointments, once daily, till the complete healing achieved. Wound healing was assessed by analyzing % wound closure, hydroxyproline content, epithelialization period, tensile strength, enzymatic antioxidative status and inflammatory markers. Total phenolic and flavonoid content of the extract was estimated to be 112.32±1.12 and 84.42±0.47mg/g, respectively. HPLC-DAD of nBuTP confirmed the presence of chlorogenic acid (20.74±0.03), protocatechuic acid (34.45±0.02mg/g), caffeic acid (4.31±0.03mg/g) and ferulic acid (1.43±0.01mg/g). 5% and 10%w/w nBuTP ointment significantly accelerated the wound healing process dose-dependently in both wound models, evidenced by the faster rate of wound contraction, epithelialization, increased hydroxyproline content, high tensile strength, increased antioxidant enzyme activity, decreased the level of inflammatory markers compared to the control group. Histopathological studies also revealed the dose-dependant amelioration of wound healing by re-epithelialization, collagenation and vascularization of wounded skin sample in nBuTP treated groups. These results implicate potential medicinal value of nBuTP to heal dermal wounds.

A Novel Nude Mouse Model of Hypertrophic Scarring Using Scratched Full Thickness Human Skin Grafts

Objective: Hypertrophic scar (HTS) is a dermal form of fibroproliferative disorder that develops following deep skin injury. HTS can cause deformities, functional disabilities, and aesthetic disfigurements. The pathophysiology of HTS is not understood due to, in part, the lack of an ideal animal model. We hypothesize that human skin with deep dermal wounds grafted onto athymic nude mice will develop a scar similar to HTS. Our aim is to develop a representative animal model of human HTS. Approach: Thirty-six nude mice were grafted with full thickness human skin with deep dermal scratch wound before or 2 weeks after grafting or without scratch. The scratch on the human skin grafts was made using a specially designed jig that creates a wound >0.6 mm in depth. The xenografts were morphologically analyzed by digital photography. Mice were euthanized at 1, 2, and 3 months postoperatively for histology and immunohistochemistry analysis. Results: The mice developed raised and firm scars in the scratched xenografts with more contraction, increased infiltration of macrophage, and myofibroblasts compared to the xenografts without deep dermal scratch wound. Scar thickness and collagen bundle orientation and morphology resembled HTS. The fibrotic scars in the wounded human skin were morphologically and histologically similar to HTS, and human skin epithelial cells persisted in the remodeling tissues for 1 year postengraftment. Innovation and Conclusions: Deep dermal injury in human skin retains its profibrotic nature after transplantation, affording a novel model for the assessment of therapies for the treatment of human fibroproliferative disorders of the skin.

Review: African medicinal plants with wound healing properties

ETHNOPHARMACOLOGICAL RELEVANCE

Wounds of various types including injuries, cuts, pressure, burns, diabetic, gastric and duodenal ulcers continue to have severe socio-economic impact on the cost of health care to patients, family and health care institutions in both developing and developed countries. However, most people in the developing countries, especially Africa, depend on herbal remedies for effective treatment of wounds. Various in vitro and in vivo parameters are used for the evaluation of the functional activity of medicinal plants by using extracts, fractions and isolated compounds. The aim of the review is to identify African medicinal plants with wound healing properties within the last two decades.

MATERIALS AND METHODS

Electronic databases such as PubMed, Scifinder(®) and Google Scholar were used to search and filter for African medicinal plants with wound healing activity. The methods employed in the evaluation of wound healing activity of these African medicinal plants comprise both in vivo and in vitro models. In vivo wound models such as excision, incision, dead space and burn wound model are commonly employed in assessing the rate of wound closure (contraction), tensile strength or breaking strength determination, antioxidant and antimicrobial activities, hydroxyproline content assay and histological investigations including epithelialisation, collagen synthesis, and granulation tissue formation. In in vitro studies, single cell systems are mostly used to study proliferation and differentiation of dermal fibroblasts and keratinocytes by monitoring typical differentiation markers like collagen and keratin.

RESULTS

In this study, 61 plants belonging to 36 families with scientifically demonstrated or reported wound healing properties were reviewed. Various plant parts including leaves, fruits, stem bark and root extracts of the plants are used in the evaluation of plants for wound healing activities.

CONCLUSION

Although, a variety of medicinal plants for wound healing can be found in literature, there is a need for the isolation and characterization of the bioactive compounds responsible for the wound healing properties. Also, cytotoxicity studies should be performed on the promising agents or bioactive fractions or extracts.

The Review on Properties of Aloe Vera in Healing of Cutaneous Wounds

Treatment of wounds is very important and was subject of different investigations. In this regard, natural substance plays crucial role as complementary medicine. Various studies reported that aloe vera has useful effects on wounds especially cutaneous wounds healing. Therefore in the current review, we examined the effect of aloe vera on cutaneous wound healing and concluded that although aloe vera improves the wound healing as well as other procedures both clinically and experimentally, more studies are still needed to approve the outcomes.

Mast cells in airway diseases and interstitial lung disease

Mast cells are major effector cells of inflammation and there is strong evidence that mast cells play a significant role in asthma pathophysiology. There is also a growing body of evidence that mast cells contribute to other inflammatory and fibrotic lung diseases such as chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis. This review discusses the role that mast cells play in airway diseases and highlights how mast cell microlocalisation within specific lung compartments and their cellular interactions are likely to be critical for their effector function in disease.

Approaches for analyzing the roles of mast cells and their proteases in vivo

The roles of mast cells in health and disease remain incompletely understood. While the evidence that mast cells are critical effector cells in IgE-dependent anaphylaxis and other acute IgE-mediated allergic reactions seems unassailable, studies employing various mice deficient in mast cells or mast cell-associated proteases have yielded divergent conclusions about the roles of mast cells or their proteases in certain other immunological responses. Such "controversial" results call into question the relative utility of various older versus newer approaches to ascertain the roles of mast cells and mast cell proteases in vivo. This review discusses how both older and more recent mouse models have been used to investigate the functions of mast cells and their proteases in health and disease. We particularly focus on settings in which divergent conclusions about the importance of mast cells and their proteases have been supported by studies that employed different models of mast cell or mast cell protease deficiency. We think that two major conclusions can be drawn from such findings: (1) no matter which models of mast cell or mast cell protease deficiency one employs, the conclusions drawn from the experiments always should take into account the potential limitations of the models (particularly abnormalities affecting cell types other than mast cells) and (2) even when analyzing a biological response using a single model of mast cell or mast cell protease deficiency, details of experimental design are critical in efforts to define those conditions under which important contributions of mast cells or their proteases can be identified.

The multifaceted mast cell in inflammatory bowel disease

Mast cells (MCs) are tissue-resident immune cells that carry out protective roles against pathogens. In disease states, such as inflammatory bowel disease, these granulocytes release a diverse array of mediators that contribute to inflammatory processes. They also participate in wound repair and tissue remodeling. In this review, the composition of MCs and how their phenotypes can be altered during inflammation of the gastrointestinal tract is detailed. Animal and human clinical studies that have implicated the participation of MCs in inflammatory bowel disease are reviewed, including the contribution of the cell's mediators to clinical symptoms, stress-triggered inflammation, and fistula and strictures. Studies that have focused on negating the proinflammatory roles of MCs and their mediators in animal models suggest new targets for therapies for patients with inflammatory bowel disease.

The role of mast cells in cutaneous wound healing in streptozotocin-induced diabetic mice

Mast cells (MCs) reside in cutaneous tissue, and an increment of MCs is suggested to induce vascular regression in the process of wound healing. To clarify participation of MCs in diabetic cutaneous wound healing, we created an excisional wound on diabetic mice 4 weeks after streptozotocin injections and subsequently investigated the healing processes for 49 days, comparing them with control mice. The rate of wound closure was not markedly different between the diabetic and control mice. In the proliferative phase at days 7 and 14, neovascularization in the wound was weaker in diabetic mice than in control mice. In the remodeling phase at day 21 and afterward, rapid vascular regression occurred in control mice; however, neovascularization was still observed in diabetic mice where the number of vessels in granulation tissues was relatively higher than in control mice. In the remodeling phase of the control mice, MCs within the wound began to increase rapidly and resulted in considerable accumulation, whereas the increment of MCs was delayed in diabetic mice. In addition, the number of fibroblast growth factor (FGF)- or vascular endothelial growth factor (VEGF)-immunopositive hypertrophic fibroblast-like spindle cells and c-Kit-positive/VEGFR2-positive/FcεRIα-negative endothelial progenitor cells (EPCs) were higher in diabetic wounds. In conclusion, neovascularization in the proliferative phase and vascular regression in the remodeling phase were impaired in diabetic mice. The delayed increment of MCs and sustained angiogenic stimuli by fibroblast-like spindle cells and EPCs may inhibit vascular regression in the remodeling phase and impair the wound-healing process in diabetic mice.

Neurolaena lobata L. promotes wound healing in Sprague Dawley rats

Background:

The leaves of the Neurolaena lobata (Asteraceae) plant are used to control diabetes and heal wounds and infections.

Aim:

The ethanolic extract of N. lobata leaf was evaluated for its ability to heal inflicted wounds in rats using the excision wound model.

Materials and Methods:

Animals were divided into three groups of six each. Test group animals were treated topically with an ethanolic extract of N. lobata (1:1 with petroleum jelly, 100 mg/kg/day). Standard and control group animals were treated with mupirocin and petroleum jelly, respectively. Treatment was given for 13 days and the wound area was measured on alternate days. Parameters of healing assessed were the rate of wound contraction, period of epithelialization and hydroxyproline content. Antimicrobial activity of the extract was observed against Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli.

Results:

Phytochemical analysis of the extract showed the presence of saponins, tannins, alkaloids and flavanoids. Extract-treated animals exhibited 87% reduction in the wound area over 13 days when compared with the control (78%) and standard (83%) groups (P < 0.05). A significant decrease in the epithelialization period was noticed with the extract-treated test group animals compared with the controls and the standard group animals (P < 0.008). The hydroxyproline content of the extract-treated animals was higher (230.5 ± 42.1) when evaluated against the control and (79.0 ± 32.2) and the standard (115.0 ± 44.5) groups (P < 0.05).

Conclusion:

Increase in the rate of wound contraction and hydroxyproline content with decrease in epithelialization time in extract-treated animals support further evaluation of N. lobata as a pharmacotherapy for wound healing.

Efficacy of Annona squamosa L in the synthesis of glycosaminoglycans and collagen during wound repair in streptozotocin induced diabetic rats

The aim of this work was to find out the effects of Annona squamosa on the formation of glycosaminoglycans and collagen during wound healing in normal and diabetic rats. Diabetes induced rats were segregated into 4 groups, each containing six animals. Groups I and III served as the normal and diabetic control while groups II and IV served as normal and diabetic treated. The animals were treated with 200 μL of Annona squamosa extract topically. The granulation tissues formed were removed on the 8th day and the amount of glycosaminoglycans (GAGs) and collagen formed was evaluated by sequential extraction and SDSPAGE, respectively. Histological evaluation was also carried out using Masson's trichrome stain. In vitro wound healing efficacy of A. squamosa in human dermal fibroblast culture (HDF) was also carried out. The fibroblasts treated with varying concentrations of A. squamosa were examined for proliferation and closure of the wound area and photographed. A. squamosa increased cellular proliferation in HDF culture. The granulation tissues of treated wounds showed increased levels of glycosaminoglycans (P < 0.05) and collagen which were also confirmed by histopathology. The results strongly substantiate the beneficial effects of A. squamosa on the formation of glycosaminoglycans and collagen during wound healing.

Foreign body response to subcutaneous biomaterial implants in a mast cell-deficient Kit(w-Sh) murine model

Mast cells (MCs)_are recognized for their functional role in wound-healing and allergic and inflammatory responses - host responses that are frequently detrimental to implanted biomaterials if extended beyond acute reactivity. These tissue reactions impact especially on the performance of sensing implants such as continuous glucose monitoring (CGM) devices. Our hypothesis that effective blockade of MC activity around implants could alter the host foreign body response (FBR) and enhance the in vivo lifetime of these implantable devices motivated this study. Stem cell factor and its ligand c-KIT receptor are critically important for MC survival, differentiation and degranulation. Therefore, an MC-deficient sash mouse model was used to assess MC relationships to the in vivo performance of CGM implants. Additionally, local delivery of a tyrosine kinase inhibitor (TKI) that inhibits c-KIT activity was also used to evaluate the role of MCs in modulating the FBR. Model sensor implants comprising polyester fibers coated with a rapidly dissolving polymer coating containing drug-releasing degradable microspheres were implanted subcutaneously in sash mice for various time points, and the FBR was evaluated for chronic inflammation and fibrous capsule formation around the implants. No significant differences were observed in the foreign body capsule formation between control and drug-releasing implant groups in MC-deficient mice. However, fibrous encapsulation was significantly greater around the drug-releasing implants in sash mice compared to drug-releasing implants in wild-type (e.g. MC-competent) mice. These results provide insights into the role of MCs in the FBR, suggesting that MC deficiency provides alternative pathways for host inflammatory responses to implanted biomaterials.

The Importance of Mast Cells in Dermal Scarring

Significance: Mast cells are resident inflammatory cells present in high numbers in the skin. They are one of the first cell types to respond to damage and they do so by quickly releasing a variety of preformed mediators that are stored within mast cell granules. Mast cells are not only active early on, where they help induce inflammation, but they also stimulate the proliferation of several important cell types and influence the production and remodeling of collagen. Recent Advances: Recent studies have highlighted the importance of mast cells in determining the amount of scar tissue that forms as a result of the repair process. Mast cells are found in low numbers and in a less activated state in scarless wounds, whereas high numbers of activated mast cells are associated with scarring and fibrosis. Furthermore, animals that lack mast cells or have been treated with degranulation inhibitors or drugs that block the activity of mast cell proteases have been shown to heal with reduced scar tissue. Critical Issues: Despite evidence suggesting that mast cells regulate scar tissue development, the entire range of mast cell activities during wound repair and scar formation has not been completely characterized. In addition, the potential therapeutic benefits of targeting mast cells clinically have yet to be fully explored. Future Directions: More studies are needed to determine whether inhibiting mast cell activation and blocking the function of mast cell mediators are viable options to prevent or reduce the appearance of scars.

Are mast cells instrumental for fibrotic diseases?

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disorder of unknown etiology characterized by accumulation of lung fibroblasts and extracellular matrix deposition, ultimately leading to compromised tissue architecture and lung function capacity. IPF has a heterogeneous clinical course; however the median survival after diagnosis is only 3–5 years. The pharmaceutical and biotechnology industry has made many attempts to find effective treatments for IPF, but the disease has so far defied all attempts at therapeutic intervention. Clinical trial failures may arise for many reasons, including disease heterogeneity, lack of readily measurable clinical end points other than overall survival, and, perhaps most of all, a lack of understanding of the underlying molecular mechanisms of the progression of IPF. The precise link between inflammation and fibrosis remains unclear, but it appears that immune cells can promote fibrosis by releasing fibrogenic factors. So far, however, therapeutic approaches targeting macrophages, neutrophils, or lymphocytes have failed to alter disease pathogenesis. A new cell to garner research interest in fibrosis is the mast cell. Increased numbers of mast cells have long been known to be present in pulmonary fibrosis and clinically correlations between mast cells and fibrosis have been reported. More recent data suggests that mast cells may contribute to the fibrotic process by stimulating fibroblasts resident in the lung, thus driving the pathogenesis of the disease. In this review, we will discuss the mast cell and its physiological role in tissue repair and remodeling, as well as its pathological role in fibrotic diseases such as IPF, where the process of tissue repair and remodeling is thought to be dysregulated.

Genetic ablation of mast cells redefines the role of mast cells in skin wound healing and bleomycin-induced fibrosis

Conclusive evidence for the impact of mast cells (MCs) in skin repair is still lacking. Studies in mice examining the role of MC function in the physiology and pathology of skin regenerative processes have obtained contradictory results. To clarify the specific role of MCs in regenerative conditions, here we used a recently developed genetic mouse model that allows conditional MC ablation to examine MC-specific functions in skin. This mouse model is based on the cell type-specific expression of Cre recombinase in connective tissue-type MCs under control of the Mcpt5 promoter and the Cre-inducible diphtheria toxin receptor-mediated cell lineage ablation by diphtheria toxin. In response to excisional skin injury, genetic ablation of MCs did not affect the kinetics of reepithelialization, the formation of vascularized granulation tissue, or scar formation. Furthermore, genetic ablation of MCs failed to prevent the development of skin fibrosis upon bleomycin challenge. The amount of deposited collagen and the biochemistry of collagen fibril crosslinks within fibrotic lesions were comparable in MC-depleted and control mice. Collectively, our findings strongly suggest that significant reduction of MC numbers does not affect skin wound healing and bleomycin-induced fibrosis in mice, and provide to our knowledge previously unreported insight in the long-debated contribution of MCs in skin regenerative processes.

Development of mast cells and importance of their tryptase and chymase serine proteases in inflammation and wound healing

Mast cells (MCs) are active participants in blood coagulation and innate and acquired immunity. This review focuses on the development of mouse and human MCs, as well as the involvement of their granule serine proteases in inflammation and the connective tissue remodeling that occurs during the different phases of the healing process of wounded skin and other organs. The accumulated data suggest that MCs, their tryptases, and their chymases play important roles in tissue repair. While MCs initially promote healing, they can be detrimental if they are chronically stimulated or if too many MCs become activated at the same time. The possibility that MCs and their granule serine proteases contribute to the formation of keloid and hypertrophic scars makes them potential targets for therapeutic intervention in the repair of damaged skin.

Mast cells are dispensable for normal and activin-promoted wound healing and skin carcinogenesis

The growth and differentiation factor activin A is a key regulator of tissue repair, inflammation, fibrosis, and tumorigenesis. However, the cellular targets, which mediate the different activin functions, are still largely unknown. In this study, we show that activin increases the number of mature mast cells in mouse skin in vivo. To determine the relevance of this finding for wound healing and skin carcinogenesis, we mated activin transgenic mice with CreMaster mice, which are characterized by Cre recombinase-mediated mast cell eradication. Using single- and double-mutant mice, we show that loss of mast cells neither affected the stimulatory effect of overexpressed activin on granulation tissue formation and reepithelialization of skin wounds nor its protumorigenic activity in a model of chemically induced skin carcinogenesis. Furthermore, mast cell deficiency did not alter wounding-induced inflammation and new tissue formation or chemically induced angiogenesis and tumorigenesis in mice with normal activin levels. These findings reveal that mast cells are not major targets of activin during wound healing and skin cancer development and also argue against nonredundant functions of mast cells in wound healing and skin carcinogenesis in general.

Mast cell activity in the healing wound: more than meets the eye?

Mast cells (MCs) are an important part of the innate immune system and are abundant in barrier organs such as the skin. They are known primarily for initiating allergic reactions, but many other biological functions have now been described for these cells. Studies have indicated that during wound repair, MCs enhance acute inflammation, stimulate reepithelialization and angiogenesis, and promote scarring. MCs have also been linked to abnormal healing, with high numbers of MCs observed in chronic wounds, hypertrophic scars and keloids. Although MCs have gained attention in the wound healing field, several unique features of MCs have yet to be examined in the context of cutaneous repair. These include the ability of MCs to: (i) produce anti-inflammatory mediators; (ii) release mediators without degranulating; and (iii) change their phenotype. Recent findings highlight the complexity of MCs and suggest that more information is needed to understand their complete range of activities during repair.

Evidence that mast cells are not required for healing of splinted cutaneous excisional wounds in mice

Wound healing is a complex biological process involving the interaction of many cell types to replace lost or damaged tissue. Although the biology of wound healing has been extensively investigated, few studies have focused on the role of mast cells. In this study, we investigated the possible role of mast cells in wound healing by analyzing aspects of cutaneous excisional wound healing in three types of genetically mast cell-deficient mice. We found that C57BL/6-Kit^W-sh/W-sh, WBB6F₁-Kit^W/W-v, and Cpa3-Cre; Mcl-1^fl/fl mice re-epithelialized splinted excisional skin wounds at rates very similar to those in the corresponding wild type or control mice. Furthermore, at the time of closure, scars were similar in the genetically mast cell-deficient mice and the corresponding wild type or control mice in both quantity of collagen deposition and maturity of collagen fibers, as evaluated by Masson’s Trichrome and Picro-Sirius red staining. These data indicate that mast cells do not play a significant non-redundant role in these features of the healing of splinted full thickness excisional cutaneous wounds in mice.

In vivo wound-healing efficacy and antioxidant activity of Achyranthes aspera in experimental burns

CONTEXT

The floral richness of the North-East Indian region cannot be neglected in context to its medicinal importance. Achyranthes aspera Linn. (Amaranthaceae; Prickly Chaff flower) is an indigenous plant species of this region. Although the local traditional healers have ethnomedical knowledge on the use of this plant, there is no scientific study on wound-healing activity of this plant.

OBJECTIVE

The healing efficacy of methanol leaf extract of A. aspera (MEAA) in granulation tissue of burn wound and its antioxidant activity are investigated.

MATERIALS AND METHODS

Methanol extract of leaves of A. aspera was used for compounding 5% (w/w) ointment, which was applied topically twice daily in experimental burn wound in rats. Healing potential was assessed by rate of wound contraction, antioxidant and biochemical assay which was supported by gelatin zymography and histopathology.

RESULTS

In the present study, 5% ointment of A. aspera showed significant (p < 0.05) wound healing, which was evident by wound contraction, elevation of various antioxidant enzymes viz. SOD, catalase, vitamin C and prohealing and biochemical parameters like hydroxyproline and protein content than the control animals. Up-regulated expression of matrix metalloproteinases (MMP-2 and 9) was also observed by gelatin zymography. Histopathological examination of the granulation tissues in the A. aspera-treated animals showed collagen deposition, fibroblast proliferation and formation of epidermis.

DISCUSSION AND CONCLUSION

The methanol leaf extract of A. aspera showed excellent wound-healing activities which has great potential for development of plant-based product.

Protective effects of an extract from Citrus bergamia against inflammatory injury in interferon-γ and histamine exposed human keratinocytes

AIMS

The present work evaluated the anti-inflammatory/antioxidant activity of a well characterized extract from Citrus bergamia Risso and Poiteau (CBE), containing neoeriocitrin, naringin, neohesperidin and other flavonoids, on human NCTC 2544 keratinocytes treated with interferon-gamma (IFN-γ) and histamine (H).

MAIN METHODS

High performance liquid chromatography (HPLC) coupled with diode array detectors was used to characterize and quantify phenolic compounds in CBE. Anti-inflammatory/antioxidant ability on keratinocytes was determined through evaluation of inter-cellular adhesion molecule-1 (ICAM-1) and inducible nitric oxide synthase (iNOS) expression by Western blot, production of nitric oxide (NO) with Griess reagent and concentration of reactive oxygen species (ROS) by fluorescent quantitative analysis with 2',7'-dichlorfluorescein-diacetate (DCFH-DA). Cell viability was assessed using 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Antioxidant activity was also measured by oxygen radical absorbance capacity (ORAC) assay. Glycosaminoglycans (GAGs) were quantified using 1.9-dimethyl methylene blue (DMB).

KEY FINDINGS

CBE exhibited high antioxidant activity confirmed by elevated ORAC values related to high capacity in oxygen radical scavenging. The assays on keratinocytes demonstrated that CBE does not inhibit cell proliferation and is shown to significantly reduce dose-dependently ICAM-1, iNOS, NO, ROS and GAG production in cells exposed to IFN-γ and H.

SIGNIFICANCE

Our study demonstrates that the pools of compounds of an extract from C. bergamia efficiently block the proinflammatory actions induced by IFN-γ and H on human keratinocytes. CBE may be used for topic employment in some inflammatory diseases of the skin and to represent an important opportunity for the essential oil processing industries.