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SEM image of elastic fibrous network in adult dermis. The collagen has been removed by autoclaving. Micrograph courtesy of T. Tsuji, R. Lavker and A. Kligman [21J (x 3(0).
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To describe a normal adult dermis is a seemingly simple task considering the diverse microscopic methods available for examination of the tissue, staining procedures to delineate the fibrous and cellular components, and immunolabeling techniques to identify precisely the various fibrous elements. Yet it is not simple because the range of normal in...
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Context 1
... fibers comprise only 4% of the adult dermal proteins [20) yet they form a surprisingly extensive network in the skin [21) (Fig 5). Mature elastic fibers have 2 components, a micro fibrillar scaffolding and a matrix of elastin "cement." Of these, the elastin constitutes as much as 90% of the fiber [22]. The microfibrils are 10-12 nm tubular-appearing structures com posed of 2 glycoproteins [23]. These are biochemically distinct from elastin within which they are embedded, exposed only at the surface or as darkly staining linear streaks within the unstained matrix. Alone, the microfibrils have no mechanical properties [24]. An individual fibroblast can secrete more than one type of collagen, and elastin, simultaneously [25,26], al though during development collagen and elastin are synthesized as independent events; collagen synthesis is presumed to occur ahead of synthesis of the elastin matrix ...
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Objective
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Citations
... Examination of the proteolysis of several host skin structural molecules by SmCI-1 was predicated upon the knowledge that S. mansoni products have been known to degrade host ECM at a distance from the invading larval schistosome, as well GP63's ability to degrade host ECM proteins [45, 83,84]. We elected to examine elastin and collagen type I V cleavage given their abundance in human skin [85,86]. SmCI-1 was capable of cleaving elastin, gelatin, collagen type IV, albeit at relatively low levels as compared to our a positive controls. ...
Schistosoma mansoni employs immune evasion and immunosuppression to overcome immune responses mounted by its snail and human hosts. Myriad immunomodulating factors underlie this process, some of which are proteases. Here, we demonstrate that one protease, an invadolysin we have termed SmCI-1, is released from the acetabular glands of S. mansoni cercaria and is involved in creating an immunological milieu favorable for survival of the parasite. The presence of SmCI-1 in the cercarial stage of S. mansoni is released during transformation into the schistosomula. SmCI-1 functions as a metalloprotease with the capacity to cleave collagen type IV, gelatin and fibrinogen. Additionally, complement component C3b is cleaved by this protease, resulting in inhibition of the classical and alternative complement pathways. Using SmCI-1 knockdown cercariae, we demonstrate that SmCI-1 protects schistosomula from complement-mediated lysis in human plasma. We also assess the effect of SmCI-1 on cytokine release from human peripheral blood mononuclear cells, providing compelling evidence that SmCI-1 promotes an anti-inflammatory microenvironment by enhancing production of IL-10 and suppressing the production of inflammatory cytokines like IL-1B and IL-12p70 and those involved in eosinophil recruitment and activation, like Eotaxin-1 and IL-5. Finally, we utilize the SmCI-1 knockdown cercaria in a mouse model of infection, revealing a role for SmCI-1 in S. mansoni survival.
... A epiderme superficial forma uma barreira ininterrupta que varia em espessura de 0,07 mm a 0,12 mm, em grande parte da Research, Society and Development, v. 11, n. 16, e565111638359, 2022 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v11i16.38359 7 superfície do corpo, contribuindo pouco para as propriedades mecânicas (Ramshaw, 1986;Smith, Holbrook, & Byers, 1982 Comportamento semelhante foi observado na literatura (Kamoun et al., 2015). ...
A pele é o maior órgão do corpo humano e tem como principal função proteger todo o organismo contra a ação de agentes externos. Devido às lesões provocadas nesse órgão e ao avanço tecnológico nas diversas áreas, investigações têm sido cada vez mais frequentes sobre as membranas poliméricas para uso como curativos, tendo em vista que elas devem ser atóxicas, possuir alta capacidade de intumescimento, consistência macia, que minimiza o atrito entre o tecido e a membrana. Uma ampla diversidade de polímeros hidrofílicos vem sendo utilizados na preparação de membranas. Neste trabalho, as propriedades de membranas constituídas a partir de um polipeptídeo de alta massa molar proveniente da desnaturação e degradação estrutural do colágeno animal, gelatina (GE) tipo I, e do polímero produzido através da polimerização do acetato de vinila seguido de reação de hidrólise do poli(acetato de vinila), poli(álcool vinílico) (PVA) com 80% de grau de hidrólise, foram investigadas. A mistura desses materiais na preparação de membranas visa obter um material com excelentes propriedades, devido estes, por si só, já apresentarem boas propriedades ópticas, hidrofilicidade, boa resistência mecânica, características essenciais para uso como curativos. Para tanto, foram produzidas pelo método casting, membranas puras de GE e PVA, bem como diferentes composições de 1/3, 1/4, 3/1 e 4/1 v/v de GE/PVA, respectivamente. A partir do aspecto visual, pôde-se observar membranas macias, flexíveis, translúcidas e incolores à luz visível com espessura média de 27,01 μm, para aplicação em lesões/ferimentos superficiais na região da derme, que possui de 70 a 120 μm de espessura.
... These injury depths indicate deeper dermal tissue, such as the papillary dermis layer is removed along with the epidermis, indicating partial-thickness avulsions occur. This increased depth is attributable to strong adhesion from the high surface area, interdigitated DEJ pulling some of the dermis along as the skin surface is stripped 8,15,62 . ...
Partial-thickness cutaneous injuries distributed over exposed body locations, such as the face and extremities, pose a significant risk of infection, function loss, and extensive scarring. These injuries commonly result from impact of kinetic debris from industrial accidents or blast weaponry such as improvised explosive devices. However, the quantitative connections between partial-thickness injuries and debris attributes (kinetic energy, shape, orientation, etc.) remain unknown, with little means to predict damage processes or design protection. Here we quantitatively characterize damage in near-live human skin after impact by debris-simulating kinetic projectiles at differing impact angles and energies. Impact events are monitored using high-speed and quantitative imaging to visualize skin injuries. These findings are utilized to develop a highly predictive, dynamic computational skin-injury model. Results provide quantitative insights revealing how the dermal-epidermal junction controls more severe wound processes. Findings can illuminate expected wound severity and morbidity risks to inform clinical treatment, and assess effectiveness of emerging personal protective equipment. Berkey and colleagues quantitatively characterized partial-thickness cutaneous injuries after impact from projectiles simulating ballistic fragments. A corresponding damage model was developed to simulate and predict the cutaneous damage from impact, which could guide protective equipment design and clinical treatment.
... Therefore 2 mm (average thickness of dermis layer) was considered for the thickness of the skin graft model [1,14]. Previous studies reported the computational work on the angles of 0°and 90°only [15][16][17]. In this work, the slit angles of the skin graft models were varied from 0°to 90°with the interval of 15°to investigate the effect of slit orientation on graft expansions. ...
The ability to expand skin grafts is essential in treating severe burn injuries that require donor skin for transplantation. While most graft mesh manufacturers claim high expansions, the practical expansions observed to date with skin grafts are much lower. To investigate this gap, we studied the biomechanics of skin grafts, considering the common graft pattern orientation, and varied the slit angle to evaluate the mesh expansion and induced stresses. Seven skin graft patterns were designed and modeled for this study, ranging from 0° to 90° with a gap of 15° between the two-consecutive models. A detailed mesh convergence study was carried out to estimate an optimal mesh for accurate and time-efficient results. The results of the finite element modeling were analyzed in terms of deformation, induced stresses up to the ultimate tensile stress (UTS), and meshing or expansion ratio. The expansion ratio was reported to be below 1 for low stretching and increased significantly up to 2.8 at the UTS. High applied strains were associated with high localized induced stresses, which varied with the graft orientation. With varying slit patterning in skin grafts, it was observed that expansions higher than that of traditional grafts could be achieved without overstretching. These findings will aid in the development of novel graft designs with high expansion in the future.
... [24][25][26][27] For epidermis, the thickness values range from 0.07 to 0.12 mm, whereas for dermis, it is between 1 and 4 mm depending upon the location considered over the body. [28][29][30] In this work, split-thickness skin grafts (STSG) were studied, which contain a full portion of epidermis and partial portions of dermis. Therefore, the skin was simulated as a two-layered model having 0.1 and 1.9 mm as the thicknesses of epidermis and dermis, respectively, with a width and length as 25 mm each ( Figure 1). ...
Over 20 million burn injuries are reported every year, with severe cases requiring skin grafting. Traditionally, split thickness skin grafts are preparedby excising a small portion of healthy skin and its incision patterning using a suitable meshing device, which allows the graft to be expandedbeyond its capacity. To date, the maximum expansion achieved through skin graftinghas been reported to be less than 3 times, which is notsufficient for covering large burn sites with limited donor site skin.In this work, we have attempted to study skin graft expansion potential with novel auxetic patterns, which are known to exhibit negative Poisson’s effect. Two‐layer skin graft models were developed using eight different auxetic incision patterns,and subjected to uniaxial and biaxial tensile strains.The Poisson’s ratio, meshing ratio, and induced stresses were characterized for all graft models. The numerical results indicated expansion potentials greater than that of traditional skin grafts across all loads. Extremely high expansions (i.e., >30 times) were estimated for the I‐Shaped Re‐entrant andRotating Triangles shaped auxetic models without rupture. Such pioneering findings are anticipated to initiate ground‐breaking advances towards skin graft researchand improved outcomes in burn surgeries. This article is protected by copyright. All rights reserved.
... The dermis, the middle layer, has a variety of collagens in various orientations. All multi-layered heterogeneous materials make up the bottom layer, hypodermis, which generally contains subcutaneous fat covering the muscles [10][11][12].The epidermis thickness varies from 0.07 mm to 0.12 mm, while the dermis thickness varies from 1 mm to 4 mm, depending on the body area [13][14][15]. A two-layer skin model geometry was created with a complete epidermis layer and a partial dermis layer for split thickness skin graft based simulations. ...
Due to a dearth of skin substitutes, severe burn injuries result in millions of deaths every year. Split thickness skin grafting, which involves the projection of a parallel incision pattern on a small section of excised healthy skin, is commonly used to improve the expansion and cover a large burn site. The true expansion capacity of such grafts is currently limited to less than three times, which is insufficient for treating severe burn damage. In this work, we investigated the expansion potential of skin grafts using alternating slit based auxetic incision designs, with the hypothesis that this would lead to greater expansion than standard graft models. Nine two-layer skin graft models were developed with varying slit lengths and spacing, and the Poisson's ratio, meshing ratios, and induced stresses were estimated under uniaxial and biaxial load tests. For up to 100% applied strains, the Poisson's ratio increased with increase in the unit cell spacing. For the biaxial tests, equal lengths of the slits of the pattern, with a high unit cell spacing, was found to lead to a greater skin cover and lower stress localization in the graft models. However, when the graft models were tested up to the ultimate tensile strength of skin, a low unit cell spacing was found to be more desirable. Maximum uniaxial and biaxial meshing ratios, approximately 13 and 5 times higher than that of traditional grafts respectively, were quantified. Such expansion potentials and stress estimations with skin grafts have not been reported previously and would be indispensable for ground breaking advances in burn surgery research.
... The design of skin grafts was developed with the open-source 3D modeling software called Rhinoceros (Robert McNeel & Associates, Seattle, USA). Grafts were modeled with a specific dimension and thickness of 3 mm, and a wide range of slit sizes and spacings as shown in figure 1 [23][24][25]. The slits were placed horizontally side by side in line with literature based computational studies [16], and varying slit sizes, spacings, and orientations were implemented. ...
Skin graft expansion is the key to the treatment of severe burn injuries requiring skin transplantation. While high expansions have been claimed by a majority of graft manufacturers, the realistic expansions reported to date with skin grafts are much lower. To clarify this discrepancy, we attempted to understand the biomechanics of skin grafts through the study of common graft pattern sizes, spacing, and orientation, and their influence on mesh expansion and induced stress. A novel skin simulant material and additive manufacturing were employed to develop the skin graft models. Tensile testing experiments were conducted to study expansion and overall stresses, and a finite element model (FEM) was used to characterize the local trends. At low strains (i.e., <1), the mesh expansion ratio was reported to be below 1, which increased up to 1.93 at a high strain of 2. The pattern size and spacing were not observed to affect the expansion much (i.e., <10%). With a change in orientation, the expansion decreased across all graft models and strains. High localized induced stresses were reported for high strains, which varied with graft orientation. The novel observations highlight the achievable expansions without overstressing, with standard slit patterning in skin grafts. These findings will not only help achieve better mesh expansion outcomes in burn surgeries but also guide the development of novel graft patterns for enhanced expansion in the future.
... Hypodermis contains the subcutaneous fat covering the muscles, and are all multilayered heterogeneous materials [16,22]. The thickness of the epidermis ranges from 0.07 mm to 0.12 mm, while the thickness of the dermis ranges from 1 mm to 4 mm, depending on the region of the body [23][24][25]. Herein, we developed a two-layer skin model with a complete epidermis and partial dermis layer. Figure 1 shows the unit cell model and a complete skin graft design with both the skin layers. ...
Severe burn injures lead to millions of fatalities every year due to lack of skin replacements. While skin is a very limited and expensive entity, split thickness skin grafting, which involves the projection of a parallel incision pattern on a small section of healthy excised skin, is typically employed to increase the expansion and cover a larger burn site. To date, the real expansion capacity of such grafts are low (<3 times) and insufficient for treatment of severe burn injuries. In this study, novel I-shaped auxetic incision patterns, which are known to exhibit high negative Poisson’s ratios, have been tested on the skin to investigate their expansion potential. Fourteen two-layer skin graft models with varying incision pattern parameters (i.e., length, spacing, and orientation) were developed using finite element modelling and tested under uniaxial and biaxial tensile loads. The Poisson’s ratio, meshing ratios, and induced stresses were quantified across all models. Graft models tested uniaxially along the orthogonal directions indicated opposite trends in generated Poisson’s ratios, as the length of the I-shape incisions were increased. Biaxially, with a symmetric and closely spaced I-shape pattern, graft meshing ratios up to 15.65 were achieved without overstressing the skin. Overall, the findings from the study indicated that expansion potentials much higher than that of traditional skin grafts can be achieved with novel I-shaped auxetic skin grafts, which would be indispensable for covering large wounds in severe burn injuries.
... The skin is also an interesting and sophisticated collagen-based organ [16]. The skin structure resembles a net consisting of differently oriented collagen fibers [17][18][19]. ...
The growing applications of tissue engineering technologies warrant the search and development of biocompatible materials with an appropriate strength and elastic moduli. Here, we have extensively studied a collagenous membrane (GSCM) separated from the mantle of the Giant squid Dosidicus Gigas in order to test its potential applicability in regenerative medicine. To establish the composition and structure of the studied material, we analyzed the GSCM by a variety of techniques, including amino acid analysis, SDS-PAGE, and FTIR. It has been shown that collagen is a main component of the GSCM. The morphology study by different microscopic techniques from nano-to microscale revealed a peculiar packing of collagen fibers forming laminae oriented at 60-90 degrees in respect to each other, which, in turn, formed layers with the thickness of several microns (a basketweave motif). The macro-and micromechanical studies showed high values of the Young's modulus and tensile strength. No significant cytotoxicity of the studied material was found by the cytotoxicity assay. Thus, the GSCM consists of a reinforced collagen network, has high mechanical characteristics, and is non-toxic, which makes it a good candidate for the creation of a scaffold material for tissue engineering.
... The skin is largely divided into the epidermis and the dermis, of which the dermis occupies most of the skin structure, with a thickness 10 to 40 times that of the epidermis [29]. Collagen type I is the most abundant component of the ECM that comprises the dermis and is responsible for the strength and elasticity of the skin [30]. ...
Resveratrol (RES) and oxyresveratrol (OXYRES) are considered and utilized as active ingredients of anti-aging skin cosmetics. However, these compounds are susceptible to oxidative discoloration and unpleasant odor in solutions, limiting their use in cosmetics. Accordingly, RES and OXYRES were chemically modified to acetylated derivatives with enhanced stability, and their anti-aging effect on the skin and detailed molecular mechanism of their acetylated derivatives were investigated. Acetylated RES and OXYRES lost their acetyl group and exerted an inhibitory effect on H2O2-induced ROS levels in human dermal fibroblast (HDF) cells. In addition, RES, OXYRES, and their acetylated derivatives suppressed UVB-induced matrix metalloproteinase (MMP)-1 expression via inhibition of mitogen-activated protein kinases (MAPKs) and Akt/mTOR signaling pathways. Furthermore, RES, OXYRES, and their acetylated derivatives suppressed type I collagen in TPA-treated HDF cells. Collectively, these results suggest the beneficial effects and underlying molecular mechanisms of RES, OXYRES, and their acetylated derivatives for anti- skin aging applications.
