Extracellular Matrix and Dermal Fibroblast Function in the Healing Wound

The Reparative Abilities of Menstrual Stem Cells Modulate the Wound Matrix Signals and Improve Cutaneous Regeneration

Considerable advances have been made toward understanding the cellular and molecular mechanism of wound healing, however, treatments for chronic wounds remain elusive. Emerging concepts utilizing mesenchymal stem cells (MSCs) from umbilical cord, adipose tissue and bone marrow have shown therapeutical advantages for wound healing. Based on this positive outcome, efforts to determine the optimal sources for MSCs are required in order to improve their migratory, angiogenic, immunomodulatory, and reparative abilities. An alternative source suitable for repetitive, non-invasive collection of MSCs is from the menstrual fluid (MenSCs), displaying a major practical advantage over other sources. This study aims to compare the biological functions and the transcriptomic pattern of MenSCs with umbilical cord MSCs in conditions resembling the wound microenvironment. Consequently, we correlate the specific gene expression signature from MenSCs with changes of the wound matrix signals in vivo. The direct comparison revealed a superior clonogenic and migratory potential of MenSCs as well as a beneficial effect of their secretome on human dermal fibroblast migration in vitro. Furthermore, MenSCs showed increased immunomodulatory properties, inhibiting T-cell proliferation in co-culture. We further, investigated the expression of selected genes involved in wound repair (growth factors, cytokines, chemokines, AMPs, MMPs) and found considerably higher expression levels in MenSCs (ANGPT1 1.5-fold; PDGFA 1.8-fold; PDGFB 791-fold; MMP3 21.6-fold; ELN 13.4-fold; and MMP10 9.2-fold). This difference became more pronounced under a pro-inflammatory stimulation, resembling wound bed conditions. Locally applied in a murine excisional wound splinting model, MenSCs showed a significantly improved wound closure after 14 days, as well as enhanced neovascularization, compared to the untreated group. Interestingly, analysis of excised wound tissue revealed a significantly higher expression of VEGF (1.42-fold) among other factors, translating an important conversion of the matrix signals in the wound site. Furthermore, histological analysis of the wound tissue from MenSCs-treated group displayed a more mature robust vascular network and a genuinely higher collagen content confirming the pro-angiogenic and reparative effect of MenSCs treatment. In conclusion, the superior clonogenicity, immunosuppressive and migration potential in combination with specific paracrine signature of MenSCs, resulted in an enhanced wound healing and cutaneous regeneration process.

A built-in electric field with nanoscale distinction for cell behavior regulation

To mimic the electrical properties of collagen fibrils on a bone surface, a built-in nanoscale electric field is formed on the surface of a polypyrrole (PPy) coating-decorated potassium-sodium niobate (KNN) piezoceramic. With the fabrication strategy, the piezoelectricity of KNN after polarization results in the formation of an electric field on the surface, which could be regulated by adjusting the polarization process. Then, conductive PPy nanoarrays (CPNAs) are obtained on the surfaces of the KNN piezoceramics. The conductive PPy transports the electric field to the coating surface, and the nanoarray morphology results in variations in the surface potential, leading to a built-in nanoscale electric field. Biological characterization indicates that CPNAs exhibit acceptable biocompatibility. Moreover, the nanoscale electric field regulates cell behavior, and the relatively high surface potential promotes cell proliferation, cell attachment and osteogenic differentiation.

Differential response of human dermal fibroblast subpopulations to visible and near-infrared light: Potential of photobiomodulation for addressing cutaneous conditions

BACKGROUND OBJECTIVES

The past decade has witnessed a rapid expansion of photobiomodulation (PBM), demonstrating encouraging results for the treatment of cutaneous disorders. Confidence in this approach, however, is impaired not only by a lack of understanding of the light-triggered molecular cascades but also by the significant inconsistency in published experimental outcomes, design of the studies and applied optical parameters. This study aimed at characterizing the response of human dermal fibroblast subpopulations to visible and near-infrared (NIR) light in an attempt to identify the optical treatment parameters with high potential to address deficits in aging skin and non-healing chronic wounds.

MATERIALS AND METHODS

Primary human reticular and papillary dermal fibroblasts (DF) were isolated from the surplus of post-surgery human facial skin. An in-house developed LED-based device was used to irradiate cell cultures using six discrete wavelengths (450, 490, 550, 590, 650, and 850 nm). Light dose-response at a standard oxygen concentration (20%) at all six wavelengths was evaluated in terms of cell metabolic activity. This was followed by an analysis of the transcriptome and procollagen I production at a protein level, where cells were cultured in conditions closer to in vivo at 2% environmental oxygen and 2% serum. Furthermore, the production of reactive oxygen species (ROS) was accessed using real-time fluorescence confocal microscopy imaging. Here, production of ROS in the presence or absence of antioxidants, as well as the cellular localization of ROS, was evaluated.

RESULTS

In terms of metabolic activity, consecutive irradiation with short-wavelength light (⇐530 nm) exerted an inhibitory effect on DF, while longer wavelengths (>=590 nm) had essentially a neutral effect. Cell behavior following treatment with 450 nm was biphasic with two distinct states: inhibitory at low- to mid- dose levels (<=30 J/cm² ), and cytotoxic at higher dose levels (>30 J/cm² ). Cell response to blue light was accompanied by a dose-dependent release of ROS that was localized in the perinuclear area close to mitochondria, which was attenuated by an antioxidant. Overall, reticular DFs exhibited a greater sensitivity to light treatment at the level of gene expression than did papillary DFs, with more genes significantly up- or down- regulated. At the intra-cellular signaling pathway level, the up- or down- regulation of vital pathways was observed only for reticular DF, after treatment with 30 J/cm² of blue light. At the cellular level, short visible wavelengths exerted a greater inhibitory effect on reticular DF. Several genes involved in the TGF-β signaling pathway were also affected. In addition, procollagen I production was inhibited. By contrast, 850 nm near-infrared (NIR) light (20 J/cm² ) exerted a stimulatory metabolic effect in these cells, with no detectable intracellular ROS formation. Here too, reticular DF were more responsive than papillary DF. This stimulatory effect was only observed under in vivo-like low oxygen conditions, corresponding to normal dermal tissue oxygen levels (approximately 2%).

CONCLUSION

This study highlights a differential impact of light on human skin cells with upregulation of metabolic activity with NIR light, and inhibition of pro-collagen production and proliferation in response to blue light. These findings open-up new avenues for developing therapies for different cutaneous conditions (e.g., treatment of keloids and fibrosis) or differential therapy at distinct stages of wound healing. Lasers Surg. Med. 50:859-882, 2018. © 2018 Wiley Periodicals, Inc.

Wound Healing and Omega-6 Fatty Acids: From Inflammation to Repair

Wound healing is an evolutionarily conserved process that is essential for species survival. Wound healing involves a series of biochemical and cellular events that are tightly controlled, divided into 3 concomitant and overlapping phases: inflammation, proliferation, and remodelling. Poor wound healing or a chronic wound represents a silent epidemic that affects billions of people worldwide. Considering the involvement of immune cells in its resolution, recent studies are focused on investigating the roles of immune nutrients such as amino acids, minerals, and fatty acids on wound healing. Among the fatty acids, much attention has been given to omega-6 (ω-6) fatty acids since they can modulate cell migration and proliferation, phagocytic capacity, and production of inflammatory mediators. The present review summarizes current knowledge about the role of ω-6 fatty acids in the wound healing context.

Fabrication and In Vitro Characterization of Electrochemically Compacted Collagen/Sulfated Xylorhamnoglycuronan Matrix for Wound Healing Applications

Skin autografts are in great demand due to injuries and disease, but there are challenges using live tissue sources, and synthetic tissue is still in its infancy. In this study, an electrocompaction method was applied to fabricate the densely packed and highly ordered collagen/sulfated xylorhamnoglycuronan (SXRGlu) scaffold which closely mimicked the major structure and components in natural skin tissue. The fabricated electrocompacted collagen/SXRGlu matrices (ECLCU) were characterized in terms of micromorphology, mechanical property, water uptake ability and degradability. The viability, proliferation and morphology of human dermal fibroblasts (HDFs) cells on the fabricated matrices were also evaluated. The results indicated that the electrocompaction process could promote HDFs proliferation and SXRGlu could improve the water uptake ability and matrices' stability against collagenase degradation, and support fibroblast spreading on the ECLCU matrices. Therefore, all these results suggest that the electrocompacted collagen/SXRGlu scaffold is a potential candidate as a dermal substitute with enhanced biostability and biocompatibility.

Insights into the key roles of epigenetics in matrix macromolecules-associated wound healing

Extracellular matrix (ECM) is a dynamic network of macromolecules, playing a regulatory role in cell functions, tissue regeneration and remodeling. Wound healing is a tissue repair process necessary for the maintenance of the functionality of tissues and organs. This highly orchestrated process is divided into four temporally overlapping phases, including hemostasis, inflammation, proliferation and tissue remodeling. The dynamic interplay between ECM and resident cells exerts its critical role in many aspects of wound healing, including cell proliferation, migration, differentiation, survival, matrix degradation and biosynthesis. Several epigenetic regulatory factors, such as the endogenous non-coding microRNAs (miRNAs), are the drivers of the wound healing response. microRNAs have pivotal roles in regulating ECM composition during wound healing and dermal regeneration. Their expression is associated with the distinct phases of wound healing and they serve as target biomarkers and targets for systematic regulation of wound repair. In this article we critically present the importance of epigenetics with particular emphasis on miRNAs regulating ECM components (i.e. glycoproteins, proteoglycans and matrix proteases) that are key players in wound healing. The clinical relevance of miRNA targeting as well as the delivery strategies designed for clinical applications are also presented and discussed.

Mechanical forces in skin disorders

Mechanical forces are known to regulate homeostasis of the skin and play a role in the pathogenesis of skin diseases. The epidermis consists of keratinocytes that are tightly adhered to each other by cell junctions. Defects in keratins or desmosomal/hemidesmosomal proteins lead to the attenuation of mechanical strength and formation of intraepidermal blisters in the case of epidermolysis bullosa simplex. The dermis is rich in extracellular matrix, especially collagen, and provides the majority of tensile force in the skin. Keloid and hypertrophic scar, which is the result of over-production of collagen by fibroblasts during the wound healing, are associated with extrinsic tensile forces and changes of intrinsic mechanical properties of the cell. Increasing evidences shows that stiffness of the skin environment determines the regenerative ability during wound healing process. Mechanotransduction pathways are also involved in the morphogenesis and cyclic growth of hair follicles. The development of androgenetic alopecia is correlated to tensile forces generated by the fibrous tissue underlying the scalp. Acral melanoma predominantly occurs in the weight-bearing area of the foot suggesting the role of mechanical stress. Increased dermal stiffness from fibrosis might be the cause of recessive dystrophic epidermolysis bullosa associated squamous cell carcinoma. Strategies to change the mechanical forces or modify the mechanotransduction signals may lead to a new way to treat skin diseases and promote skin regeneration.

Biomaterials for Skin Substitutes

Patients with extensive burns rely on the use of tissue engineered skin due to a lack of sufficient donor tissue, but it is a challenge to identify reliable and economical scaffold materials and donor cell sources for the generation of a functional skin substitute. The current review attempts to evaluate the performance of the wide range of biomaterials available for generating skin substitutes, including both natural biopolymers and synthetic polymers, in terms of tissue response and potential for use in the operating room. Natural biopolymers display an improved cell response, while synthetic polymers provide better control over chemical composition and mechanical properties. It is suggested that not one material meets all the requirements for a skin substitute. Rather, a composite scaffold fabricated from both natural and synthetic biomaterials may allow for the generation of skin substitutes that meet all clinical requirements including a tailored wound size and type, the degree of burn, the patient age, and the available preparation technique. This review aims to be a valuable directory for researchers in the field to find the optimal material or combination of materials based on their specific application.

The peritoneal "soil" for a cancerous "seed": a comprehensive review of the pathogenesis of intraperitoneal cancer metastases

Various types of tumors, particularly those originating from the ovary and gastrointestinal tract, display a strong predilection for the peritoneal cavity as the site of metastasis. The intraperitoneal spread of a malignancy is orchestrated by a reciprocal interplay between invading cancer cells and resident normal peritoneal cells. In this review, we address the current state-of-art regarding colonization of the peritoneal cavity by ovarian, colorectal, pancreatic, and gastric tumors. Particular attention is paid to the pro-tumoral role of various kinds of peritoneal cells, including mesothelial cells, fibroblasts, adipocytes, macrophages, the vascular endothelium, and hospicells. Anatomo-histological considerations on the pro-metastatic environment of the peritoneal cavity are presented in the broader context of organ-specific development of distal metastases in accordance with Paget's "seed and soil" theory of tumorigenesis. The activity of normal peritoneal cells during pivotal elements of cancer progression, i.e., adhesion, migration, invasion, proliferation, EMT, and angiogenesis, is discussed from the perspective of well-defined general knowledge on a hospitable tumor microenvironment created by the cellular elements of reactive stroma, such as cancer-associated fibroblasts and macrophages. Finally, the paper addresses the unique features of the peritoneal cavity that predispose this body compartment to be a niche for cancer metastases, presents issues that are topics of an ongoing debate, and points to areas that still require further in-depth investigations.

Comparison of Human Dermal Fibroblasts and HaCat Cells Cultured in Medium with or without Serum via a Generic Tissue Engineering Research Platform

A generic research platform with 2-dimensional (2D) cell culture technology, a 3-dimensional (3D) in vitro tissue model, and a scaled-down cell culture and imaging system in between, was utilized to address the problematic issues associated with the use of serum in skin tissue engineering. Human dermal fibroblasts (HDFs) and immortalized keratinocytes (HaCat cells) mono- or co-cultured in serum or serum-free medium were compared and analyzed via the platform. It was demonstrated that serum depletion had significant influence on the attachment of HaCat cells onto tissue culture plastic (TCP), porous substrates and cellulosic scaffolds, which was further enhanced by the pre-seeded HDFs. The complex structures formed by the HDFs colonized within the porous substrates and scaffolds not only prevented the seeded HaCat cells from filtering through the open pores, but also acted as cellular substrates for HaCat cells to attach onto. When mono-cultured on TCP, both HDFs and HaCat cells were less proliferative in medium without serum than with serum. However, both cell types were successfully co-cultured in 2D using serum-free medium if the initial cell seeding density was higher than 80,000 cells/cm² (with 1:1 ratio). Based on the results from 2D cultures, co-culture of both cell types on modular substrates with small open pores (125 μm) and cellulosic scaffolds with open pores of varying sizes (50–300 µm) were then conducted successfully in serum-free medium. This study demonstrated that the generic research platform had great potential for in-depth understanding of HDFs and HaCat cells cultivated in serum-free medium, which could inform the processes for manufacturing skin cells or tissues for clinical applications.

Damage-induced reactive oxygen species regulate vimentin and dynamic collagen-based projections to mediate wound repair

Tissue injury leads to early wound-associated reactive oxygen species (ROS) production that mediate tissue regeneration. To identify mechanisms that function downstream of redox signals that modulate regeneration, a vimentin reporter of mesenchymal cells was generated by driving GFP from the vimentin promoter in zebrafish. Early redox signaling mediated vimentin reporter activity at the wound margin. Moreover, both ROS and vimentin were necessary for collagen production and reorganization into projections at the leading edge of the wound. Second harmonic generation time-lapse imaging revealed that the collagen projections were associated with dynamic epithelial extensions at the wound edge during wound repair. Perturbing collagen organization by burn wound disrupted epithelial projections and subsequent wound healing. Taken together our findings suggest that ROS and vimentin integrate early wound signals to orchestrate the formation of collagen-based projections that guide regenerative growth during efficient wound repair.

Transplantation of human amnion prevents recurring adhesions and ameliorates fibrosis in a rat model of sciatic nerve scarring

Peripheral nerve fibrosis and painful adhesions are common, recurring pathological sequelae following injury. In this study, vital human amnion (hAM), an increasingly interesting biomaterial for regenerative medicine, was investigated as a novel therapy. hAM was first analyzed in vitro regarding its anti-adhesive characteristics. Then, the reflected region of hAM which was identified as more suitable, was transplanted into female Sprague Dawley rats with recurring sciatic nerve scarring (n = 24) and compared with untreated controls (n = 30) at one, four and twelve weeks. Immune response and fibrosis were investigated by (immuno)histochemical analysis. Nerve structure was examined and function determined using electrophysiology and gait analysis. Here we identified strongly reduced adhesions in the hAM-treated rats, displaying a significant difference at four weeks post transplantation compared to untreated controls (p = .0052). This correlated with the in vitro cell attachment test on hAM explants, which demonstrated a distinctly limited ability of fibroblasts to adhere to amniotic epithelial cells. Upon hAM transplantation, significantly less intraneural fibrosis was identified at the later time points. Moreover, hAM-treated rats exhibited a significantly higher sciatic functional index (SFI) after four weeks compared to controls (p < .05), which indicated a potentially pro-regenerative effect of hAM. As a possible explanation, an impact of hAM on the endogenous immune response, including T cell and macrophage subsets, was indicated. We conclude that hAM is strongly effective against recurring nerve scarring and induces an anti-fibrotic and pro-regenerative effect, making it highly promising for treating adhesion-related disorders.

STATEMENT OF SIGNIFICANCE

Abnormal fibrotic bonding of tissues, frequently involving peripheral nerves, affects millions of people worldwide. These so-called adhesions usually cause severe pain and drastically reduce quality of life. To date, no adequate treatment exists and none is routinely used in the clinical practice. In this study, vital human amnion, the innermost of the fetal membranes, was transplanted in a rat model of peripheral nerve scarring and recurring adhesions as novel therapeutic approach. Amniotic cells have already demonstrated to feature stem-cell like properties and produce pro-regenerative factors, which makes the amnion an increasingly promising biomaterial for regenerative medicine. We identified that its transplantation was very effective against peripheral nerve scarring and distinctly reduced recurring adhesions. Moreover, we identified a pro-regenerative effect. This study showed that the amnion is a highly promising novel therapeutic approach for adhesion-related disorders.

Extracellular matrix contribution to skin wound re-epithelialization

The ability of skin to act as a barrier is primarily determined by cells that maintain the continuity and integrity of skin and restore it after injury. Cutaneous wound healing in adult mammals is a complex multi-step process that involves overlapping stages of blood clot formation, inflammation, re-epithelialization, granulation tissue formation, neovascularization, and remodeling. Under favorable conditions, epidermal regeneration begins within hours after injury and takes several days until the epithelial surface is intact due to reorganization of the basement membrane. Regeneration relies on numerous signaling cues and on multiple cellular processes that take place both within the epidermis and in other participating tissues. A variety of modulators are involved, including growth factors, cytokines, matrix metalloproteinases, cellular receptors, and extracellular matrix components. Here we focus on the involvement of the extracellular matrix proteins that impact epidermal regeneration during wound healing.

Tissue Engineered Skin Substitutes

The fundamental skin role is to supply a supportive barrier to protect body against harmful agents and injuries. Three layers of skin including epidermis, dermis and hypodermis form a sophisticated tissue composed of extracellular matrix (ECM) mainly made of collagens and glycosaminoglycans (GAGs) as a scaffold, different cell types such as keratinocytes, fibroblasts and functional cells embedded in the ECM. When the skin is injured, depends on its severity, the majority of mentioned components are recruited to wound regeneration. Additionally, different growth factors like fibroblast growth factor (FGF), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF) are needed to orchestrated wound healing process. In case of large surface area wounds, natural wound repair seems inefficient. Inspired by nature, scientists in tissue engineering field attempt to engineered constructs mimicking natural healing process to promote skin restoration in untreatable injuries. There are three main types of commercially available engineered skin substitutes including epidermal, dermal, and dermoepidermal. Each of them could be composed of scaffold, desired cell types or growth factors. These substitutes could have autologous, allogeneic, or xenogeneic origin. Moreover, they may be cellular or acellular. They are used to accelerate wound healing and recover normal skin functions with pain relief. Although there are a wide variety of commercially available skin substitutes, almost none of them considered as an ideal equivalents required for proper wound healing.

Wound healing-related properties detected in an experimental model with a collagen gel contraction assay are affected in the absence of tenascin-X

Patients with tenascin-X (TNX)-deficient type Ehlers-Danlos syndrome (EDS) do not exhibit delayed wound healing, unlike classic type EDS patients, who exhibit mutations in collagen genes. Similarly, in TNX-knockout (KO) mice, wound closure of the skin is normal even though these mice exhibit a reduced breaking strength. Therefore, we speculated that the wound healing process may be affected in the absence of TNX. In this study, to investigate the effects of TNX absence on wound healing-related properties, we performed collagen gel contraction assays with wild-type (WT) and TNX-KO mouse embryonic fibroblasts (MEFs). Collagen gels with embedded TNX-KO MEFs showed significantly greater contraction than those containing WT MEFs. Subsequently, we assessed collagen gel contraction-related properties, such as the activities of matrix metalloproteinase (MMP)-2 and MMP-9 and the protein and mRNA expression levels of transforming growth factor β1 (TGF-β1) in the collagen gels. The activities of MMP-2 and MMP-9 and the expression level of TGF-β1 were elevated in the absence of TNX. Furthermore, filopodia-like protrusion formation, cell proliferation, migration, and collagen expression in MEFs were promoted in the absence of TNX. These results indicate that these wound healing-related properties are affected in a TNX-deficient extracellular environment.

Zinc in Wound Healing Modulation

Wound care is a major healthcare expenditure. Treatment of burns, surgical and trauma wounds, diabetic lower limb ulcers and skin wounds is a major medical challenge with current therapies largely focused on supportive care measures. Successful wound repair requires a series of tightly coordinated steps including coagulation, inflammation, angiogenesis, new tissue formation and extracellular matrix remodelling. Zinc is an essential trace element (micronutrient) which plays important roles in human physiology. Zinc is a cofactor for many metalloenzymes required for cell membrane repair, cell proliferation, growth and immune system function. The pathological effects of zinc deficiency include the occurrence of skin lesions, growth retardation, impaired immune function and compromised would healing. Here, we discuss investigations on the cellular and molecular mechanisms of zinc in modulating the wound healing process. Knowledge gained from this body of research will help to translate these findings into future clinical management of wound healing.

The role of bone marrow mononuclear cell-conditioned medium in the proliferation and migration of human dermal fibroblasts

Background

Several recent studies have demonstrated the great potential of bone marrow cells in regenerative medicine, not only for their ability to differentiate to match a damaged cell type, but also because they synthesize and release various growth factors and cytokines.

We examined the effect of bone marrow cell-conditioned medium in the healing process, especially in terms of fibroblast proliferation and migration.

Methods

These in vitro studies consisted of co-culture (without direct contact) of dermal fibroblasts with mononuclear bone marrow cells and the use of conditioned medium obtained from these cultures in a scratch wound model.

Results

Mononuclear cells were found to increase the proliferation of fibroblasts, and the conditioned medium showed a stimulatory effect on the migration of fibroblasts.

Conclusion

When considered together with the observed increase in growth factor levels in conditioned medium, it appears that these cells act through a paracrine mechanism.

Inhibition of the receptor for advanced glycation promotes proliferation and repair of human periodontal ligament fibroblasts in response to high glucose via the NF-κB signaling pathway

OBJECTIVE

To observe if inhibition of the receptor for advanced glycation endproducts (RAGE) promotes proliferation and repair of human periodontal ligament fibroblasts (hPDLFs) stimulated by high glucose. In addition, we also discuss the effects of the NF-κB signaling pathway in relation to this process.

METHODS

Primary cultured hPDLFs were exposed to either low glucose (5.5 mmol/L) or high glucose (25 mmol/L), and RAGE expression was measured by Western blot analysis. Cells were cultured in high glucose with different concentrations of the RAGE inhibitor, FPS-ZM1. We measured cell proliferation using the Cell Counting Kit-8 and expression of collagen type 1 and fibronectin by real-time PCR and ELISA, respectively. The relative protein expression levels of NF-κB p65 and phosphorylated p65 were measured by Western blot analysis.

RESULTS

High glucose enhanced RAGE expression and suppressed cell growth. While FPS-ZM1 increased proliferation and expression of repair-related factors in high glucose, there was a concurrent decline in the phosphorylation level of NF-κB p65.

CONCLUSION

FPS-ZM1 rescued the proliferative capacity and repair capability of hPDLFs via the RAGE-NF-κB signaling pathway in response to high glucose.

Immunological challenges associated with artificial skin grafts: available solutions and stem cells in future design of synthetic skin

The repair or replacement of damaged skins is still an important, challenging public health problem. Immune acceptance and long-term survival of skin grafts represent the major problem to overcome in grafting given that in most situations autografts cannot be used. The emergence of artificial skin substitutes provides alternative treatment with the capacity to reduce the dependency on the increasing demand of cadaver skin grafts. Over the years, considerable research efforts have focused on strategies for skin repair or permanent skin graft transplantations. Available skin substitutes include pre- or post-transplantation treatments of donor cells, stem cell-based therapies, and skin equivalents composed of bio-engineered acellular or cellular skin substitutes. However, skin substitutes are still prone to immunological rejection, and as such, there is currently no skin substitute available to overcome this phenomenon. This review focuses on the mechanisms of skin rejection and tolerance induction and outlines in detail current available strategies and alternatives that may allow achieving full-thickness skin replacement and repair.

Subcellular Interactions during Vascular Morphogenesis in 3D Cocultures between Endothelial Cells and Fibroblasts

Background: Increasing the complexity of in vitro systems to mimic three-dimensional tissues and the cellular interactions within them will increase the reliability of data that were previously collected with in vitro systems. In vivo vascularization is based on complex and clearly defined cell–matrix and cell–cell interactions, where the extracellular matrix (ECM) seems to play a very important role. The aim of this study was to monitor and visualize the subcellular and molecular interactions between endothelial cells (ECs), fibroblasts, and their surrounding microenvironment during vascular morphogenesis in a three-dimensional coculture model. Methods: Quantitative and qualitative analyses during the generation of a coculture tissue construct consisting of endothelial cells and fibroblasts were done using transmission electron microscopy and immunohistochemistry. Results: Dynamic interactions were found in cocultures between ECs, between fibroblasts (FBs), between ECs and FBs, and between the cells and the ECM. Microvesicles were involved in intercellular information transfer. FBs took an active and physical part in the angiogenesis process. The ECM deposited by the cells triggered endothelial angiogenic activity. Capillary-like tubular structures developed and matured. Moreover, some ECM assembled into a basement membrane (BM) having three different layers equivalent to those seen in vivo. Finally, the three-dimensional in vitro construct mirrored the topography of histological tissue sections. Conclusion: Our results visualize the importance of the physical contact between all cellular and acellular components of the cocultures.

The effects of artocarpin on wound healing: in vitro and in vivo studies

The skin protects the body against harmful substances and microorganisms. When the skin is damaged, wound healing must be finely regulated to restore the normal function of skin tissue. Artocarpin (ARTO), a prenylated flavonoid purified from the plant Artocarpus communis, has been reported to have anti-inflammatory and anti-cancer properties. The aim of the present study was to evaluate the wound healing potential and therapeutic mechanism of ARTO. Immunohistochemical staining of neutrophils and macrophages and mouse cytokine array analysis demonstrated that ARTO accelerates inflammatory progression and subsequently decreases persistent inflammation. ARTO increases collagen production and increases human fibroblast proliferation and migration by activating the P38 and JNK pathways. Moreover, ARTO increases the proliferation and migration of human keratinocytes through the ERK and P38 pathways and augments human endothelial cell proliferation and tube formation through the Akt and P38 pathways. Together, our data suggested that ARTO enhances skin wound healing, possibly by accelerating the inflammatory phase and by increasing myofibroblast differentiation, proliferation and migration of fibroblasts and keratinocytes, collagen synthesis and maturation, re-epithelialization, and angiogenesis. These findings indicate that ARTO has potential as a potent therapeutic agent for the treatment of skin wounds.

Effects of Dermatopontin gene silencing on apoptosis and proliferation of osteosarcoma MG‑63 cells

The present study aimed to investigate the effect of Dermatopontin (DPT) gene silencing on the apoptosis and proliferation of osteosarcoma MG‑63 cells. Three eukaryotic expression vectors of short hairpin (sh)RNA fragments targeting different loci of DPT were designed and transfected into an osteosarcoma cell line MG‑63. The cells were assigned to a blank, shRNA‑control, DPT‑shRNA‑a, DPT‑shRNA‑b or DPT‑shRNA‑c group. The shRNA with the highest silencing efficiency was screened using reverse transcription‑quantitative polymerase chain reaction and western blotting. The screened shRNA was transfected into MG‑63 cells. The proliferation, cell cycle and apoptosis of MG‑63 cells were measured using a Cell Counting Kit‑8 assay, flow cytometry and Annexin V‑fluorescein isothiocyanate assay. The recombinant plasmids containing DPT shRNA were successfully constructed. DPT gene silencing was able to significantly reduce the proliferation rate of MG‑63 cells (P<0.05). The proportion of cells in the G0/G1 phase and in the G2/M phase increased significantly (both P<0.05), while the proportion of cells in the S phase decreased (P<0.05). Furthermore, the cell apoptosis rate increased significantly (P<0.05). These results demonstrate that DPT gene silencing is able to reduce the proliferation of MG‑63 cells, slow down cell cycle progression and promote apoptosis, hence may become a novel target for the treatment of osteosarcoma.

Redox Signaling in Diabetic Wound Healing Regulates Extracellular Matrix Deposition

SIGNIFICANCE

Impaired wound healing is a major complication of diabetes, and can lead to development of chronic foot ulcers in a significant number of patients. Despite the danger posed by poor healing, very few specific therapies exist, leaving patients at risk of hospitalization, amputation, and further decline in overall health. Recent Advances: Redox signaling is a key regulator of wound healing, especially through its influence on the extracellular matrix (ECM). Normal redox signaling is disrupted in diabetes leading to several pathological mechanisms that alter the balance between reactive oxygen species (ROS) generation and scavenging. Importantly, pathological oxidative stress can alter ECM structure and function.

CRITICAL ISSUES

There is limited understanding of the specific role of altered redox signaling in the diabetic wound, although there is evidence that ROS are involved in the underlying pathology.

FUTURE DIRECTIONS

Preclinical studies of antioxidant-based therapies for diabetic wound healing have yielded promising results. Redox-based therapeutics constitute a novel approach for the treatment of wounds in diabetes patients that deserve further investigation. Antioxid. Redox Signal. 27, 823-838.

Collagen peptides modulate the metabolism of extracellular matrix by human dermal fibroblasts derived from sun-protected and sun-exposed body sites

Clinical data published in recent years have demonstrated positive effects of collagen hydrolysate (CH) on skin aging clinical signs. CH use as food supplement has a long history; however, few studies have addressed the underlying purpose of CH on the cellular and molecular biology of skin cells that could elucidate clinical improvement findings. Wide diversity of characteristics has been reported for dermal fibroblasts derived from different body sites and it is unknown whether collagen peptides could modulate differently cells from chronological aged and photoaged skin areas. This study investigated the influence of CH on the extracellular matrix metabolism and proliferation of human dermal fibroblasts (HDFs) derived from chronological aged (sun-protected) and photoaged (sun-exposed) body sites. CH treatment did not affect cellular proliferation of either cell cultures, but notably modulated cell metabolism in monolayer model, increasing the content of dermal matrix precursor and main protein, procollagen I and collagen I, respectively. These effects were confirmed in the human dermal equivalent model. The increase in collagen content in the cultures was attributed to stimulation of biosynthesis and decreased collagen I metabolism through inhibition of metalloproteinase activity (MMP) 1 and 2. Modulation of CH in dermal metabolism did not differ between cells derived from sun-protected and sun-exposed areas, although lower concentrations of CH seemed to be enough to stimulate sun-exposed-derived HDFs, suggesting more pronounced effect in these cells. This study contributes to understanding the biological effects of CH on skin cells and viability of its use as a functional ingredient in food supplements.

Stem Cell Secretome and Its Effect on Cellular Mechanisms Relevant to Wound Healing

Stem cells introduced to site of injury primarily act via indirect paracrine effects rather than direct cell replacement of damaged cells. This gives rise to understanding the stem cell secretome. In this study, in vitro studies demonstrate that the secretome activates the PI3K/Akt or FAK/ERK1/2 signaling cascades and subsequently enhances the proliferative and migratory abilities of various types of skin cells, such as fibroblasts, keratinocytes, and vascular epithelial cells, ultimately accelerating wound contraction. Indeed, inhibition of these signaling pathways with synthetic inhibitors resulted in the disruption of secretome-induced beneficial effects on various skin cells. In addition, major components of the stem cell secretome (EGF, basic FGF, and HGF) may be responsible for the acceleration of wound contraction. Stimulatory effects of these three prominent factors on wound contraction are achieved through the upregulation of PI3K/Akt or FAK/ERK1/2 activity. Overall, we lay the rationale for using the stem cell secretome in promoting wound contraction. In vivo wound healing studies are warranted to test the significance of our in vitro findings.

Zoledronate Impairs Socket Healing after Extraction of Teeth with Experimental Periodontitis

Osteonecrosis of the jaws (ONJ) is a rare but severe complication of antiresorptive medications, such as bisphosphonates, used in the treatment of bone malignancy or osteoporosis. Tooth extraction and dental disease have been strongly associated with ONJ development. Here, we investigated molecular and cellular markers of socket healing after extraction of healthy or teeth with experimental periodontitis (EP) in Wistar-Han rats treated with zoledronic acid (ZA). We included 4 experimental groups: vehicle-treated animals with extraction of healthy teeth or teeth with ligature-induced EP and ZA-treated animals with extraction of healthy teeth or teeth with EP. Animals were pretreated with vehicle or ZA for a week, and EP was induced. Four weeks later, the second maxillary molars were extracted; sockets were allowed to heal for 4 wk; animals were euthanized; and maxillae were isolated. Radiographically, extraction sockets in groups 1, 2, and 3 demonstrated normal healing. Contrary incomplete socket healing was noted after extraction of teeth with EP in ZA-treated rats of group 4. Histologically, persistent inflammation and extensive osteonecrosis were seen in group 4. Disorganization of the collagen network, collagen type III predominance, and lack of collagen fiber insertion in the necrotic bone were associated with impaired socket healing. Cells positive for MMP-9, MMP-13, and α-SMA expression were present at the areas of epithelial invagination and adjacent to osteonecrotic bone. Importantly, human biopsies from patients with ONJ showed similar findings. Our data emphasize the importance of dental disease and tooth extraction in ONJ pathogenesis and help delineate an altered profile in wound-healing markers during ONJ development.

Characterizing Cell Migration Within Three-dimensional In Vitro Wound Environments

Currently, most in vitro models of wound healing, such as well-established scratch assays, involve studying cell migration and wound closure on two-dimensional surfaces. However, the physiological environment in which in vivo wound healing takes place is three-dimensional rather than two-dimensional. It is becoming increasingly clear that cell behavior differs greatly in two-dimensional vs. three-dimensional environments; therefore, there is a need for more physiologically relevant in vitro models for studying cell migration behaviors in wound closure. The method described herein allows for the study of cell migration in a three-dimensional model that better reflects physiological conditions than previously established two-dimensional scratch assays. The purpose of this model is to evaluate cell outgrowth via the examination of cell migration away from a spheroid body embedded within a fibrin matrix in the presence of pro- or anti-migratory factors. Using this method, cell outgrowth from the spheroid body in a three-dimensional matrix can be observed and is easily quantifiable over time via brightfield microscopy and analysis of spheroid body area. The effect of pro-migratory and/or inhibitory factors on cell migration can also be evaluated in this system. This method provides researchers with a simple method of analyzing cell migration in three-dimensional wound associated matrices in vitro, thus increasing the relevance of in vitro cell studies prior to the use of in vivo animal models.

18ß-glycyrrhetinic acid derivative promotes proliferation, migration and aquaporin-3 expression in human dermal fibroblasts

Licorice (Glycyrrhiza) species have been widely used as a traditional medicine and a natural sweetener in foods. The 18β-glycyrrhetinic acid (18β-GA) is a bioactive compound in licorice that exhibits potential anti-cancer, anti-inflammatory, and anti-microbial activities. Many synthesized derivatives of 18β-GA have been reported to be cytotoxic and suggested for the treatment of malignant diseases. In this study, we explored the possible pharmacological roles of an 18β-GA derivative in skin biology using primary human dermal fibroblasts and HaCaT keratinocytes as cell models. We found that this 18β-GA derivative did not cause cell death, but significantly enhanced the proliferation of dermal fibroblasts and HaCaT keratinocytes. A scratch wound healing assay revealed that the 18β-GA derivative promoted the migration of fibroblasts. Due to the important role of aquaporin-3 in cell migration and proliferation, we also investigated the expression of aquaporin-3 and found this compound up-regulated the expression of aquaporin-3 in dermal fibroblasts and HaCaT keratinocytes. In dermal fibroblasts, the 18β-GA derivative induced the phosphorylation of Akt, ERK, and p38. The inhibitor of Akt predominantly suppressed the 18β-GA derivative-induced expression of aquaporin-3. Collectively, this compound had a positive effect on the proliferation, migration, and aquaporin-3 expression of skin cells, implying its potential role in the treatment of skin diseases characterized by impaired wound healing or dermal defects.

Identification of a myofibroblast-specific expression signature in skin wounds

After skin injury fibroblasts migrate into the wound and transform into contractile, extracellular matrix-producing myofibroblasts to promote skin repair. Persistent activation of myofibroblasts can cause excessive fibrotic reactions, but the underlying mechanisms are not fully understood. We used SMA-GFP transgenic mice to study myofibroblast recruitment and activation in skin wounds. Myofibroblasts were initially recruited to wounds three days post injury, their number reached a maximum after seven days and subsequently declined. Expression profiling showed that 1749 genes were differentially expressed in sorted myofibroblasts from wounds seven days post injury. Most of these genes were linked with the extracellular region and cell periphery including genes encoding for extracellular matrix proteins. A unique panel of core matrisome and matrisome-associated genes was differentially expressed in myofibroblasts and several genes not yet known to be linked to myofibroblast-mediated wound healing were found (e.g. Col24a1, Podnl1, Bvcan, Tinagl1, Thbs3, Adamts16, Adamts19, Cxcl's, Ccl's). In addition, a complex network of G protein-coupled signaling events was regulated in myofibroblasts (e.g. Adcy1, Plbc4, Gnas). Hence, this first characterization of a myofibroblast-specific expression profile at the peak of in situ granulation tissue formation provides important insights into novel target genes that may control excessive ECM deposition during fibrotic reactions.

The impact of quercetin on wound healing relates to changes in αV and β1 integrin expression

Overly fibrotic wound healing can lead to excess scar formation, causing functional impairment and undesirable cosmetic results. However, there are few successful treatments available to prevent or remediate scars. This study sought to explore the molecular mechanisms by which quercetin, a naturally-occurring antifibrotic agent, diminishes scar formation. Using both mice and fibroblast cells, we examined quercetin's impact on fibrosis and the wound healing rate, and potential molecular mechanisms underlying the quercetin-mediated reduction of fibrosis. While cultured fibroblasts demonstrated normal growth in response to quercetin, quercetin increased surface αV integrin and decreased β1 integrin. These changes in surface integrin expression may impact factors that contribute to fibrosis including cell migration, proliferation, and extracellular matrix production. In both quercetin-treated and control mice, wounds healed in about 14 days. Masson's trichrome stain revealed diminished fibrosis at the wound site in quercetin-treated animals despite the normal healing rate, indicating the potential for better cosmetic results without delaying healing. An in vitro scratch wound model using cells plated on an artificial extracellular matrix demonstrated delayed closure following quercetin treatment. The extracellular matrix also ameliorated quercetin's effect on αV integrin. Thus, αV integrin recruitment in response to quercetin treatment may promote the quercetin-mediated decrease extracellular matrix because cells require less extracellular matrix to migrate into a wound. With added extracellular matrix, β1 integrin remained diminished in response to quercetin, indicating that quercetin's effect on β1 integrin expression is independent of extracellular matrix -mediated signaling and is likely driven by inhibition of the intracellular mechanisms driving β1 expression. These findings suggest that quercetin could alter the cells' interactions with the extracellular matrix through the regulation of integrin expression to promote a decrease in fibrosis. Furthermore, this work demonstrates that this naturally occurring and commercially available supplement could be used to improve wound healing by impacting integrin expression, leading to a lower extracellular matrix requirement to achieve healing. Impact statement Scar formation during wound healing can be problematic for patients but there are limited therapies available to treat or prevent excess fibrosis at wound sites. This work examines the impact of quercetin, a flavonoid that decreases fibrosis, on wound healing, and relates quercetin's effects to changes in integrin expression on the surface of fibroblast cells. To our knowledge, this is the first report that quercetin alters integrin expression or that this impact may be part of the mechanism by which quercetin prevents fibrosis. This work demonstrates that quercetin can be used to modulate integrin expression and that this effect may in turn reduce fibrosis during wound healing. Furthermore, this paper identifies the modulation of integrin expression as a possible therapeutic target in preventing scars. This information could be used to improve therapeutics to aid in the cosmetic and functional results following wound healing.

Spatial distributions of pericellular stiffness in natural extracellular matrices are dependent on cell-mediated proteolysis and contractility

Bulk tissue stiffness has been correlated with regulation of cellular processes and conversely cells have been shown to remodel their pericellular tissue according to a complex feedback mechanism critical to development, homeostasis, and disease. However, bulk rheological methods mask the dynamics within a heterogeneous fibrous extracellular matrix (ECM) in the region proximal to a cell (pericellular region). Here, we use optical tweezers active microrheology (AMR) to probe the distribution of the complex material response function (α=α'+α″, in units of µm/nN) within a type I collagen ECM, a biomaterial commonly used in tissue engineering. We discovered cells both elastically and plastically deformed the pericellular material. α' is wildly heterogeneous, with 1/α' values spanning three orders of magnitude around a single cell. This was observed in gels having a cell-free 1/α' of approximately 0.5nN/µm. We also found that inhibition of cell contractility instantaneously softens the pericellular space and reduces stiffness heterogeneity, suggesting the system was strain hardened and not only plastically remodeled. The remaining regions of high stiffness suggest cellular remodeling of the surrounding matrix. To test this hypothesis, cells were incubated within the type I collagen gel for 24-h in a media containing a broad-spectrum matrix metalloproteinase (MMP) inhibitor. While pericellular material maintained stiffness asymmetry, stiffness magnitudes were reduced. Dual inhibition demonstrates that the combination of MMP activity and contractility is necessary to establish the pericellular stiffness landscape. This heterogeneity in stiffness suggests the distribution of pericellular stiffness, and not bulk stiffness alone, must be considered in the study of cell-ECM interactions and design of complex biomaterial scaffolds.

STATEMENT OF SIGNIFICANCE

Collagen is a fibrous extracellular matrix (ECM) protein widely used to study cell-ECM interactions. Stiffness of ECM has been shown to instruct cells, which can in turn modify their ECM, as has been shown in the study of cancer and regenerative medicine. Here we measure the stiffness of the collagen microenvironment surrounding cells and quantitatively measure the dependence of pericellular stiffness on MMP activity and cytoskeletal contractility. Competent cell-mediated stiffening results in a wildly heterogeneous micromechanical topography, with values spanning orders of magnitude around a single cell. We speculate studies must consider this notable heterogeneity generated by cells when testing theories regarding the role of ECM mechanics in health and disease.

Interspecies NASH disease activity whole-genome profiling identifies a fibrogenic role of PPARα-regulated dermatopontin

Nonalcoholic fatty liver disease prevalence is soaring with the obesity pandemic, but the pathogenic mechanisms leading to the progression toward active nonalcoholic steatohepatitis (NASH) and fibrosis, major causes of liver-related death, are poorly defined. To identify key components during the progression toward NASH and fibrosis, we investigated the liver transcriptome in a human cohort of NASH patients. The transition from histologically proven fatty liver to NASH and fibrosis was characterized by gene expression patterns that successively reflected altered functions in metabolism, inflammation, and epithelial-mesenchymal transition. A meta-analysis combining our and public human transcriptomic datasets with murine models of NASH and fibrosis defined a molecular signature characterizing NASH and fibrosis and evidencing abnormal inflammation and extracellular matrix (ECM) homeostasis. Dermatopontin expression was found increased in fibrosis, and reversal of fibrosis after gastric bypass correlated with decreased dermatopontin expression. Functional studies in mice identified an active role for dermatopontin in collagen deposition and fibrosis. PPARα activation lowered dermatopontin expression through a transrepressive mechanism affecting the Klf6/TGFβ1 pathway. Liver fibrotic histological damages are thus characterized by the deregulated expression of a restricted set of inflammation- and ECM-related genes. Among them, dermatopontin may be a valuable target to reverse the hepatic fibrotic process.

The extracellular matrix of eggshell displays anti-inflammatory activities through NF-κB in LPS-triggered human immune cells

Avian eggshell membrane (ESM) is a natural biomaterial that has been used as an alternative natural bandage on burned and cut skin injuries for >400 years in Asian countries, and is available in large quantities from egg industries. Our aim was to characterize ESM that was separated and processed from egg waste, and to study whether this material possesses anti-inflammatory properties, making it suitable as an ingredient in industrial production of low cost wound healing products. Our results show that the processed ESM particles retain a fibrous structure similar to that observed for the native membrane, and contain collagen, and carbohydrate components such as hyaluronic acid and sulfated glycosaminoglycans, as well as N-glycans, mostly with uncharged structures. Furthermore, both processed ESM powder and the ESM-derived carbohydrate fraction had immunomodulation properties in monocytes and macrophage-like cells. Under inflammatory conditions induced by lipopolysaccharide, the ESM powder and the isolated carbohydrate fraction reduced the activity of the transcription factor nuclear factor-κB. The expression of the immune regulating receptors toll-like receptor 4 and ICAM-1, as well as the cell surface glycoprotein CD44, all important during inflammation response, were down-regulated by these fractions. Interestingly, our experiments show that the two fractions regulated cytokine secretion differently: ESM depressed inflammation by increased secretion of the anti-inflammatory cytokine IL-10 while the carbohydrate fraction reduced secretions of the pro inflammatory cytokines IL-1β and IL-6. Also, the phosphorylation of p65 and p50 subunits of nuclear factor-κB, as well as nuclear localization, differed between processed ESM powder and carbohydrate fraction, suggesting different down-stream regulation during inflammation. In conclusion, processed ESM powder and its soluble carbohydrate components possess anti-inflammatory properties, demonstrating the potential of ESM as a novel biological wound dressing for treatment of chronic inflammatory wounds.

Antimicrobial peptide KSL-W promotes gingival fibroblast healing properties in vitro

We investigated the effect of synthetic antimicrobial decapeptide KSL-W (KKVVFWVKFK) on normal human gingival fibroblast growth, migration, collagen gel contraction, and α-smooth muscle actin protein expression. Results show that in addition to promoting fibroblast adhesion by increasing F-actin production, peptide KSL-W promoted cell growth by increasing the S and G2/M cell cycle phases, and enhanced the secretion of metalloproteinase (MMP)-1 and MMP-2 by upregulating MMP inhibitors, such as tissue inhibitors of metalloproteinase (TIMP)-1 and TIMP-2 in fibroblasts. An in vitro wound healing assay confirmed that peptide KSL-W promoted fibroblast migration and contraction of a collagen gel matrix. We also demonstrated a high expression of α-smooth muscle actin by gingival fibroblasts being exposed to KSL-W. This work shows that peptide KSL-W enhances gingival fibroblast growth, migration, and metalloproteinase secretion, and the expression of α-smooth muscle actin, thus promoting wound healing.

Current Advancements and Strategies in Tissue Engineering for Wound Healing: A Comprehensive Review

Significance: With an aging population leading to an increase in diabetes and associated cutaneous wounds, there is a pressing clinical need to improve wound-healing therapies. Recent Advances: Tissue engineering approaches for wound healing and skin regeneration have been developed over the past few decades. A review of current literature has identified common themes and strategies that are proving successful within the field: The delivery of cells, mainly mesenchymal stem cells, within scaffolds of the native matrix is one such strategy. We overview these approaches and give insights into mechanisms that aid wound healing in different clinical scenarios. Critical Issues: We discuss the importance of the biomimetic niche, and how recapitulating elements of the native microenvironment of cells can help direct cell behavior and fate. Future Directions: It is crucial that during the continued development of tissue engineering in wound repair, there is close collaboration between tissue engineers and clinicians to maintain the translational efficacy of this approach.

Effect of BTXA on Inhibiting Hypertrophic Scar Formation in a Rabbit Ear Model

BACKGROUND

Hypertrophic scar (HS) is a refractory skin disease caused by major physical damage or other inflammation. Some reports found that botulinum toxin type A (BTXA) could be an alternative treatment of the HS. Therefore, the authors studied the effects of BTXA on the treatment of HS and the dose response of BTXA.

METHODS

Hypertrophic scars were harvested from the ears of 18 young adult New Zealand big-eared rabbits and treated with BTXA or triamcinolone acetonide (TAC) in vivo experiment. The hypertrophic index (HI) was measured by histological examination. Collagen fibrils were checked by sirius red straining, and the cell nucleuses of fibroblasts were checked by Ki67.

RESULTS

The HI of hypertrophic scars with BTXA treatment was lower than that with phosphate-buffered saline treatment (P < 0.05). Compared with the TAC treatment group, the efficacy of treatment with the middle dose of BTXA (1.0, 1.5 IU) had no significant difference, as shown by sirius red staining and immunohistochemistry Ki67.

CONCLUSION

These results demonstrated that BTXA effectively improved the appearance of hypertrophic scars and inhibited the formation of collagen fibrils and fibroblasts in vivo. Treatment with the middle dose of BTXA achieved similar efficacy as TAC treatment, indicating that BTXA might be useful for inhibiting hypertrophic scars and worth investigating further.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Effect of a high-fat diet and alcohol on cutaneous repair: A systematic review of murine experimental models

BACKGROUND AND PURPOSE

Chronic alcohol intake associated with an inappropriate diet can cause lesions in multiple organs and tissues and complicate the tissue repair process. In a systematic review, we analyzed the relevance of alcohol and high fat consumption to cutaneous and repair, compared the main methodologies used and the most important parameters tested. Preclinical investigations with murine models were assessed to analyze whether the current evidence support clinical trials.

METHODS

The studies were selected from MEDLINE/PubMed and Scopus databases, according to Fig 1. All 15 identified articles had their data extracted. The reporting bias was investigated according to the ARRIVE (Animal Research: Reporting of in Vivo Experiments) strategy.

RESULTS

In general, animals offered a high-fat diet and alcohol showed decreased cutaneous wound closure, delayed skin contraction, chronic inflammation and incomplete re-epithelialization.

CONCLUSION

In further studies, standardized experimental design is needed to establish comparable study groups and advance the overall knowledge background, facilitating data translatability from animal models to human clinical conditions.

Fabrication of a three dimensional spongy scaffold using human Wharton's jelly derived extra cellular matrix for wound healing

The Wharton's jelly (WJ) contains significant amounts of extracellular matrix (ECM) components and rich source of endogenous growth factors. In this study, we designed a new biomimetic spongy scaffold from decellularized WJ-derived ECM and used it as a skin substitute. Histological analysis and biochemical assays showed that bio-active molecules preserved in the fabricated scaffolds and that the scaffolds have highly interconnected porous structure. Cytotoxicity and mechanical evaluation of the scaffold indicated that it is non-toxic and has appropriate mechanical properties. MTT assay, SEM and histological analysis of human fibroblast, seeded on the scaffolds, confirmed cellular viability, attachment, penetration and proliferation. The effectiveness of WJ-derived scaffolds in the regeneration of full-thickness wound was assessed through an in vivo experiment. Our results demonstrated that the scaffolds were well integrated into the mouse tissue and absorbed the exudates after one week. Unlike the controls, in WJ group there were not only complete wound closing and disappearance of the scab, but also complete reepithelialization, newly generated epidermal layers and appendages after 12days of implantation. Taken together, our results indicate that WJ-derived scaffolds are able to improve attachment, penetration and growth of the fibroblast cells and speed up the healing processes, which would offer a proper skin graft for wound healing.

Mammalian fibroblast cells show strong preference for laser-generated hybrid amorphous silicon-SiO2 textures

BACKGROUND

In this study, we investigated a method to produce bioactive hybrid amorphous silicon and silicon oxide patterns using nanosecond laser pulses.

METHODS

Microscale line patterns were made by laser pulses on silicon wafers at different frequencies (25, 70 and 100 kHz), resulting in ablation patterns with frequency-dependent physical and chemical properties.

RESULTS

Incubating the laser-treated silicon substrates with simulated body fluid demonstrated that the physicochemical properties of the laser-treated samples were stable under these conditions, and favored the deposition of bone-like apatite. More importantly, while NIH 3T3 fibroblasts did colonize the untreated regions of the silicon wafers, they showed a strong preference for the laser-treated regions, and further discriminated between substrates treated with different frequencies.

CONCLUSIONS

Taken together, these data suggest that laser materials processing of silicon-based devices is a promising avenue to pursue in the production of biosensors and other bionic devices.

Multimodal vaginal toning for bladder symptoms and quality of life in stress urinary incontinence

Introduction and hypothesis

Treatment options for women with stress urinary incontinence (SUI) have limitations. We hypothesized that multimodal vaginal toning therapy would improve bladder symptoms and quality of life in women with postpartum SUI and sexual function complaints.

Methods

Patients self-administered 24 sessions of multimodal vaginal toning therapy lasting 10 min each over 50 days. Outcomes included 1-h pad weight test, Urogenital Distress Inventory Short Form (UDI-6), Incontinence Impact Questionnaire-Short Form (IIQ-7), Female Sexual Distress Scale-Revised 2005 (FSDS-R), Female Sexual Function Index (FSFI), pelvic floor muscle strength, patient satisfaction, and adverse events.

Results

Of the 55 patients enrolled (safety population), 48 completed the study per-protocol (PP population). A total of 38 (79%) patients had a positive 1-h pad weight test at baseline. In this group, urine leakage was moderate or severe in 82% of patients at baseline, but in only 18% after treatment. Treatment success was 84%, defined as >50% improvement in pad weight relative to baseline. In the PP population, mean UDI-6 score improved by 50% (p < 0.001) and IIQ-7 score improved by 69% (p < 0.001). Sexual function quality of life improved by 54% for FSDS-R and 15% for FSFI (both p < 0.001). Pelvic floor muscle strength significantly improved (p < 0.001). Patient satisfaction with therapy was reported in 83% of patients. In the safety population, 2 (3.6%) adverse events were reported—1 urinary tract infection and 1 report of discomfort due to excessive warmth.

Conclusions

Multimodal vaginal toning therapy yields clinically meaningful improvements in bladder symptoms, pelvic floor muscle strength, and quality of life in women with SUI.

Conditional knockout of N-WASP in mouse fibroblast caused keratinocyte hyper proliferation and enhanced wound closure

Neural-Wiskott Aldrich Syndrome Protein (N-WASP) is expressed ubiquitously, regulates actin polymerization and is essential during mouse development. We have previously shown that N-WASP is critical for cell-ECM adhesion in fibroblasts. To characterize the role of N-WASP in fibroblast for skin development, we generated a conditional knockout mouse model in which fibroblast N-WASP was ablated using the Cre recombinase driven by Fibroblast Specific Protein promoter (Fsp-Cre). N-WASP^FKO (N-WASP^fl/fl; Fsp-cre) were born following Mendelian genetics, survived without any visible abnormalities for more than 1 year and were sexually reproductive, suggesting that expression of N-WASP in fibroblast is not critical for survival under laboratory conditions. Histological sections of N-WASP^FKO mice skin (13 weeks old) showed thicker epidermis with higher percentage of cells staining for proliferation marker (PCNA), suggesting that N-WASP deficient fibroblasts promote keratinocyte proliferation. N-WASP^FKO mice skin had elevated collagen content, elevated expression of FGF7 (keratinocyte growth factor) and TGFβ signaling proteins. Wound healing was faster in N-WASP^FKO mice compared to control mice and N-WASP deficient fibroblasts were found to have enhanced collagen gel contraction properties. These results suggest that N-WASP deficiency in fibroblasts improves wound healing by growth factor-mediated enhancement of keratinocyte proliferation and increased wound contraction in mice.

Bioelectric Field Enhancement: The Influence on Membrane Potential and Cell Migration In Vitro

Objective: The extracellular matrix consists of critical components that affect fibroblast polarization and migration. The existence of both intrinsic and extrinsic electrical signals that play essential roles in the development, physiology, regeneration, and pathology of cells was discovered over a century ago. In this study, we study how the Bioelectric Field Enhancement (BEFE) device and its generated electromagnetic field (EMF) by continuous direct current (DC) significantly affect the membrane potential and cell migration of fibroblasts in vitro. Approach: This is an experimental analysis of membrane potential and cell migration of murine fibroblasts when grown in treated media that has been reconstituted with an aqueous solution that has been exposed to an EMF, which is generated by this device versus fibroblasts grown in identically prepared control media that has not been exposed to the EMF. Results: The growth of fibroblasts in the treated media shows a strong percent change in polarization of the plasma membrane and significant increase in cell migration compared to control groups. Innovation: These experiments show the potential for an adjunct wound care therapy using a continuous DC EMF application through a medium of water. Conclusion: Growth media that was reconstituted with an aqueous solution that had been exposed to this DC derived EMF shows significant changes in cell polarity and cell migration of fibroblasts in vitro. The BEFE device has shown enhanced chronic wound healing in anecdotal reports from patients globally for decades when used as a footbath/bath and could lead to a novel EMF application in wound healing.

Skin-on-a-chip model simulating inflammation, edema and drug-based treatment

Recent advances in microfluidic cell cultures enable the construction of in vitro human skin models that can be used for drug toxicity testing, disease study. However, current in vitro skin model have limitations to emulate real human skin due to the simplicity of model. In this paper, we describe the development of ‘skin-on-a-chip’ to mimic the structures and functional responses of the human skin. The proposed model consists of 3 layers, on which epidermal, dermal and endothelial components originated from human, were cultured. The microfluidic device was designed for co-culture of human skin cells and each layer was separated by using porous membranes to allow interlayer communication. Skin inflammation and edema were induced by applying tumor necrosis factor alpha on dermal layer to demonstrate the functionality of the system. The expression levels of proinflammatory cytokines were analyzed to illustrate the feasibility. In addition, we evaluated the efficacy of therapeutic drug testing model using our skin chip. The function of skin barrier was evaluated by staining tight junctions and measuring a permeability of endothelium. Our results suggest that the skin-on-a-chip model can potentially be used for constructing in vitro skin disease models or for testing the toxicity of cosmetics or drugs.

Preoperative vitamin C supplementation improves colorectal anastomotic healing and biochemical parameters in malnourished rats

PURPOSES

The objective of this study was to evaluate the effect of supplementation with vitamin C on intestinal anastomosis healing in malnourished rats.

METHODS

Male Wistar rats were divided into three groups: (1) sham, well-nourished rats that received vehicle; (2) FR+Veh, rats that were subjected to food restriction and received vehicle; and (3) FR+VC, rats that were subjected to food restriction and received vitamin C. Four days before surgery, the animals received vitamin C (100 mg/kg/day) via gavage and underwent colon resection with anastomosis in a single plane. The survival rate of rats was monitored until day 7 after surgery. Regarding anastomosis tissues, we examined intra-abdominal adhesion index, hydroxyproline content, collagen density, inflammatory parameters, and oxidative damage to proteins and lipids.

RESULTS

Malnutrition decreases body weight and increases mortality; the survival rate was 90 % in group 1, 60 % in group 2, and 80 % in group 3. Vitamin C was able to increase hydroxyproline concentration and density of collagen and decrease the intra-abdominal adhesion index, as well as the infiltration of neutrophils and oxidative damage to proteins in malnourished rats compared to group treated with vehicle.

CONCLUSIONS

Preoperative vitamin C supplementation can improve the intestinal anastomosis healing, biochemical alterations, and prolong survival in rats subjected to food restriction.

Nanocrystalline cerium dioxide efficacy for prophylaxis of erosive and ulcerative lesions in the gastric mucosa of rats induced by stress

In our previous works, the important therapeutic properties of nanocrystalline cerium dioxide such as strong antioxidant ability, prebiotical and antibiotic activity were shown. Such properties were obtained due to stabilization of nanoparticles with precise size 3-7nm. Such modification of nanocrystalline cerium dioxide has contributed to its remarkable efficacy and low toxicity. We have carried out the investigation of toxicity of the nanodrug and revealed that in the condition of the acute toxicity test, LD 50 was 2000mg/kg when it was administered per os. This indicator is approximately 1000 times greater than effective dose of the compound that proved the possibility of its usage for humans. Considering the strong antioxidant properties of this substance, we have performed the investigation of the influence of nanocrystalline cerium dioxide on the erosive-ulcerative lesions in gastric mucosa of rats induced by Selye's restraint stress. It was established that the studied compound significantly reduced the lesions area by 58.3% (p<0.05) induced by Selye's restraint stress. The attenuation of inflammation and decrease of lipid peroxidation in the conditions of gastric lesions and prophylactic administration of nanocrystalline cerium dioxide were shown. That was confirmed by the decrease of pro-inflammatory cytokines content (interleukin (IL) 1β, 12B p40) and raise of anti-inflammatory cytokines content (IL-10 and transforming growth factor β). Measurement of lipid peroxidation products has proved the antioxidant properties of nanocrystalline cerium dioxide as it decreased the content of conjugated dienes and thiobarbituric acid active products in the conditions of gastric ulceration induced by stress.