Overview of Recombinant Skin Models and Progress in Their Application in Vitro Assessment of Toxicity and Efficacy

A recombinant skin model is a model in which skin cells are grown in vitro on a bioactive scaffold and provided with adequate nutrition to promote cell proliferation and differentiation to produce a mock skin structure and biological features. The development of recombinant skin models allows for effective and scientifically sound in vitro evaluation tests. This review briefly summarizes the overview of recombinant skin models and the progress of their application in in vitro evaluation which focuses on three aspects: skin irritation, skin corrosivity, and anti-skin aging. Moreover, an outlook on the future development of recombinant skin models is also provided in this review.

Antitumor Activity of Diallyl Sulfide in Two-StageMouse Skin Model of Carcinogenesis

It has been reported that diallyl sulfide (DAS), a sulfur-containing volatile compound in garlic (Allium sativum ), exerts anticarcinogenic activity in various rodent tumor models. In the present study, the antitumor property of DAS was tested in Swiss albino mice in the two steqe initiation-promotion mouse skin carcinogenesis. Skin cancers were initiated topically with a single subcarcinOgenic dose (52μg) of 7, 12-dimethyl benz (a) anthracene (DMBA). Promotion was performed by twice weekly applications of 12-O-tetradecanoyl phorbol-13-acetate (TPA) at a dose of 5μg/animal for 32 weeks. DAS was applied topically (250μg/animal) thrice weekly for 3 weeks for anti-initiating and 1 h prior to each promotion treatment for anti-promoting studies. The results showed that the treatment schedule of DAS can effectively delay the onset of tumorigenesis and reduce the cumulative number of tumors and the average number of tumors per mouse. In groups in which DAS applied prior to initiation or promotion, a significant population of the aniinals remained tumor-free till the termination of experiment. These findings suggest that DAS can effectively inhibit chemically induced mouse skincarcinogenesis.

Chemopreventive Effects of Black Tea Polyphenols in Mouse Skin Model of Carcinogenesis

In the present investigations, the antitumorigenic effect of black tea polyphenols (BTP) in twcrstage mouse skin model of carcinogenesis was studied. The animals were initiated with a single 'subcarcinogenic' topical dose (52 μg/200 μl acetone ) of 7, 12-dimethylbenzanthracene (DMBA). To evaluate the anti-tumour initiating activity, BTP was topically applied twice a week for three weeks prior to DMBA application, followed by topical treatment with 12-o-tetradecanoyl phorbol-13-acetate (TPA) (5 μg/200 μl acetone, 2x/wk. ) as promoter. For evaluation of antitumor promoting activity, BTP was applied prior to each treatment of TPA. BTP application showed marked inhibitory effect as antitumour initiator as well as antitumour promoter in mouse skin medel of two-stage carcinogenesis. Since initiation involves genetic pathway and tumour promotion involves epigenetic pathway, it seems that BTP exerts its antitumorigenic effect by altering both genetic and epigenetic pathways

Integrated Organ-on-a-chip with Human-induced Pluripotent Stem Cells Directional Differentiation for 3D Skin Model Generation

Keratinocytes and fibroblasts,derived from hiPSCs,were used to construct the human epidermal model by a culture patch made by monolayer poly-(lactic-co-glycolic acid)(PLGA)nanofibers and a human skin-on-a-chip device.Unlike the conventional culture dish method,two different epidermal cells are successfully adhered to the front and back sides of the patch,which produces a three-dimensional nanofibrous scaffold similar to a natural extracellular matrix before the patch was cultured in the skin-on-a-chip device to mimic the physiological conditions of human skin.As expected,the differentiated hiPSCs show the expression of keratinocyte-and fibroblast-specific proteins on the patch,and the layering is found between these two kinds of cells,indicating that this approach creates a powerful in vitro system for modeling skin development and diseases.

Validation of the Suitability of Stripped Lipid as a Skin Model in Plasma Medical Investigations

In this work, the suitability of lipid stripping as an alternative model of stratum corneum for plasma medical studies was investigated. Plasma treatment experiments were performed on samples prepared by the cyanoacrylat stripping method. Therefore, two different dielectric barrier discharge-based plasma sources driven by high-voltage pulses in the microsecond and nanosecond range were applied. The lipid sample heating, change in pH-value, and the interaction with plasma-induced UV-radiation are presented and discussed with respect to existing findings on skin samples. After the plasma treatment, the lipid stripping shows similar changes compared to human skin relating to sample heating and pH-value. The investigation of the interplay with UV- radiation shows a high absorption in the wavelength range of 250 nm up to 400 nm. Further, the thickness, surface structure, and composition of lipid stripping samples were determined. The stripped sample shows a thickness of 3 ± 1 μm whereby approximately 30% of the sample surface is covered by lipids. In addition, it was shown that there are no changes in structure caused by the sample preparation. Based on the results of this work, it can be stated that lipid stripping represents an appropriate skin model for plasma medical investigations.

Apple of Sodom (<em>Calatropis procera</em>) Callus Extract, a Novel Skincare Active and Its Biological Activity in Skin Models When Combined with Dead Sea Water

Background: Calotropis procera (C. procera), is an authentic plant naturally grown in the flora of Dead Sea region. Despite its toxicity, C. procera presents healing properties. However, it has not been implemented yet in cosmetics as an active ingredient. Objective: The biological effects of C. procera callus extract on skin were elucidated solely and in combination with Dead Sea water (DSW). Methods: The capability of C. procera extract to protect against skin inflammation and irritation was tested on ex vivo human skin organ culture by LPS and SDS addition respectively. Viability and cytokine secretion were evaluated. The combination of C. procera extract with Dead Sea water was tested on full thickness skin equivalents. Gene expression and relevant biochemical markers for glycolysis, hypoxia and extracellular matrix balance were tested. Results: C. procera extract exhibits a protective biological activity against skin irritation and inflammation at the biochemical level. Furthermore, a combination of C. procera extract and DSW demonstrates a potential contribution for skin wellbeing via enhance energy production, resistance to hypoxia and extracellular matrix balance. Conclusions: Topical application of C. procera callus extract might support skin balance and wellbeing at the molecular level. Hence, it is recommended for new cosmetic formulae as standalone or in combination with Dead Sea water, in the effort to achieve anti-aging bio-activity that is working beyond skin aging symptoms, especially via skin calming effects and skin energy enhancement.

Influence of Surface Topography on the Tactile Friction of Medical Compression Textiles against a Mechanical Skin Model

Influence of surface topography on the tactile friction of medical compression textiles was studied in this paper. The friction behavior was investigated for three kinds of medical textiles with various structures and compositions by using a textile friction analyzer under dry condition. In order to simulate the contacts of textiles/human finger, a mechanical skin model with similar texture to the skin and applied normal load oflN were selected. Meanwhile, the 3D surface topography of textiles was measured using a digital microscope. The topographical data were analyzed concerning height distribution and material ratio, and the real contact area was estimated as a function of penetration depth. Results showed that the investigated textiles revealed a significant variation on the friction coefficients, which were （ 0.41 ± 0.01 ） （ polyamide, jersey 2 × 2 ）, （0.56 ± 0. 01） （cotton, jersey 2×2） and （0. 47 ± 0. 01） （polyamide, jersey 1 × 1 ）, respectively. The textile with higher friction coefficient was found to own a relative compact and homogenous surface and larger contact area, vice versa.

Fingertip skin models for analysis of the haptic perception of textiles

This paper presents finite element models of the fingertip skin which have been created to simulate the contact of textile objects with the skin to gain a better understanding of the perception of textiles through the skin, the so-called hand of textiles. Many objective and subjective techniques have already been developed for analysing the hand of textiles;however, none of them provide exact overall information concerning the sensation of textiles through the skin. As the human skin is a complex heterogeneous hyperelastic body composed of many particles, some simplifications had to be made at the early stage of building the models;however, their utilitarian value was maintained. The models relate only to mechanical loading of the skin. They predict a low deformation of the fingertip skin under the pressure of virtual heterogeneous material: acrylic, coarse wool, and steel.

Reconstruction of 3D Skin Model and Its Application in Evaluation the Efficacy of Cosmetic Raw Materials and Active Intredients

Via the use of Mimedisc~? as a scaffold, the normal human dermal fibroblasts were first seeding into the scaffold to form a dermal equivalent after three weeks, and then seeding normal human epidermal keratinocytes on it, followed by immersion and air-liquid interphase culture stage, to finally form a 3 D sponge matrix skin model which has a very similar structure of normal human skin(NHS). The results of Masson staining, and immunohistochemistry(IHC), immunofluorescence(IF) staininccg show that this skin model has a very similar structure and key protein expression of NHS. Meanwhile, this model was used as a tool to investigate the effect of Himalaya cedar extract on Dermal-Epidermal Junction(DEJ) in vitro. Results show that the Himalayan cedar extract can significantly increase the thickness of the epidermis, thus increase the barrier capacity of the skin to resist external environment. Further, this Himalaya cedar extract can promote the expressions of Laminin 5 and Collagen VII of DEJ. The expressions of the Laminin 5 and Collagen VII increased 20% and 47% respectively.So the Himalaya cedar extract displays the potential to be applied in development of anti-aging cosmetics.

3D skin models along with skin-on-a-chip systems:A critical review

Skin is the largest organ in human body,and it plays an important role in regulating physiological microenvironments and acts as a barrier to protect human body from harmful intrusions.The demand for fully functional skin models(also called skin equivalents,SE)in an in-vivo mimicking culturing microenvironment has been increased dramatically due to the fast development in skin disease treatments and skin care products.Owing to the emerging of the concept and technology of organ-on-chips along with the three-dimensional(3D)bioprinting technology,3D skin models and their applications have been fast evolving.In this paper,the advances in the development of 3D skin models along with skin-on-a-chip(SOC)are reviewed and commented.One of the findings with this paper is that the SOC together with the 3D bioprinting technology is promising to construct fully functional 3D skin models in the field of pharmaceutical and cosmetic industries.

Establishment of Mus Skin Photo-damage Model by 8-MOP plus UVA Irradiation

To establish a simple and reliable animal model of skin photo-damage, 20 mice were treated with 8-MOP and exposed to UVA （UVA 320-400 nm） for 24 h. After irradiation, the structure of the epidermis and dermis, collagen fibers, elastic fibers were observed by using HE staining and Weigert technique and compared with the normal controls. The acanthosis and epidemis proliferation with accompanying hyperkeratosis and parakeratosis were observed. Inflammatory infiltration was noted in the dermis. The elastic fibers became coarse, irregularly arranged and clustered, with their number increased. The collagen fibers showed obvious degeneration and some amorphous materials could also be observed. The blood vessels were irregularly dilated and vascular walls were thickened, with infiltration of inflammatory cells. It is concluded that murine photodamage model can be quickly, conveniently and reliably established by means of 8-MOP/UVA.

3D Numerical Simulation of Epidermal Skin Turnover Process Using a Particle Model

Skin is the largest organ of the human body. In recent years, concern regarding the cosmetics area has increased, and research studies on anti-aging therapy or cosmetics have been rapidly conducted. Skin cells are not only changing its shape but also its physical properties during the epidermal skin turnover process. Computational simulation can be useful in further understanding the mechanisms of skin formation. We propose a particle model that can handle complex biological phenomena, including cell interactions and is a suitable method for simulating skin formation. The particle model was applied to simulate three-dimensional skin formation accompanied by proliferation and cornification of skin cells. The simulation results represented and reproduced the epidermal skin turnover phenomenon.

Use of Acellular Fish Skin for Dura Repair in an Ovine Model: A Pilot Study

Recently the use of biologic materials as dura mater repair patches has been increasing. The purpose of this study is to assess the basis for efficacy and safety of using a novel fish derived acellular dermis (Kerecis Omega3 DuraTM). In an ovine model a craniotomy under general anaesthesia was performed. A defect was produced in the dural covering of approximately 1 × 2 cm and closed with an onlay technique, with Kerecis Omega3 Dura. The bone defect was covered with the bony flap and the overlying tissues closed in layers. At 2, 5, 8 and 11 weeks the sheep underwent MRI scanning followed by euthanasia, necropsy and histological assessment. MRI images taken at 2, 5, 8 and 11 weeks showed initially moderate inflammatory response, which diminished over time, and at 11 weeks no evidence of inflammation existed. There was evidence of cerebrospinal fluid leakage at no time point. Necropsy revealed some adhesions at 5 and 8 weeks, in particular at 5 weeks, but at 11 weeks there were no adhesions found. From 2 - 11 weeks, there was evidence of initially an inflammatory reaction followed by neodura formation at the defect site through cellular ingrowth and remodeling of the acellular fish skin. Histology showed a histiocytic foreign body reaction initially that subsided over time. As early as 8 weeks there was evidence of neodura formation and by 11 weeks there was a minimal inflammatory response with an intact neodura formed. In this pilot study the Kerecis Omega3 Dura patches performed in a safe and efficacious manner. This new material needs to be fully assessed and compared with other products that are currently on the market in a larger scale animal study.

水下高速外流减摩擦阻力功效测试方案设计与验证

为了支撑高速水下航行器减摩擦阻力(摩阻)方案的选型和优化,本文提出较好的减摩阻试验研究技术方案和特征参量表达方法以提高测量精度的技术途径,并以聚氧化乙烯(PEO)减摩阻实际试验演示上述方案和途径的可行性。相关结果可为高速水下航行器减摩阻方案的选型和优化提供支撑。

基于单视图的带纹理三维人体网格参数化重建

针对计算机视觉中的三维人体重建问题,文章提出一种端到端的的网络框架,在三维和二维混合监督下,从单幅彩色图像重建带纹理信息的精准三维人体网格。使用4个编码器分别提取形状姿态特征、纹理特征、光照参数和像机参数,得到的图像特征被送入三维回归模块,迭代推断出三维人体参数;纹理参数送入纹理解码器网络得到纹理图;学习到的人体参数可转化为三维人体网格;对于损失函数的设置,预测的人体网格顶点与真实顶点的差值用来进行三维监督;通过预测的像机参数、光照参数和纹理计算二维渲染损失;通过三维关节投射得到的二维关节与图像上的二维关节真值计算二维关节重投影损失;生成对抗网络的鉴别器使得渲染图像更加真实。该文方法与现有的三维人体重建方法相比具有竞争力,而且重建的三维人体网格带有纹理信息。

基于角色建模的运动员动作动画交互演示方法

为了更好地展示动画交互效果,提升用户的体验感,提出基于角色建模的运动员动作动画交互演示方法。基于人体骨骼模型和骨骼蒙皮实现角色建模,建立三维场景,为人物活动提供虚拟环境。通过PD控制器实现对角色模型的行为控制,虚拟交互技术则实现了动画制作交互式演示。实验结果表明:该研究方法能够较好地完成人体动作交互演示,并通过交互演示延迟时间验证,证明该方法应用下的交互演示灵敏度实现了研究的预期目标。

柔性变形翼结构设计、建模与分析研究进展

未来飞行器设计将面临空域、速域不断扩大、任务适应性要求不断提高的严峻挑战,变体飞行器可为提高飞行性能、扩大飞行包线提供新思路与新方法。采用柔性蒙皮配合相应的支撑结构成为克服传统变体飞行器缺点的主要解决方案。本文首先综述了柔性蒙皮、蜂窝支撑结构、新型智能材料在变体飞行器设计中的研究现状,然后对现有文献中柔性变形翼结构设计、建模与分析方法进行讨论。最后提出现有柔性变形翼结构设计、建模与分析方法存在的问题,以及未来可能的研究方向。

人体皮肤偏振特性随其结构参数变化的研究

本文基于圆柱-双折射的皮肤真皮层简化模型,研究了人体皮肤偏振特性随其结构参数的变化特性。该工作第一次利用偏振敏感光学相干层析成像系统所测得的人体皮肤的双折射参数值,分析了其双折射、二相色性以及退偏特性随结构参数的变化而变化的特性。该研究结果对于解释偏振试验测量结果、进行临床人体皮肤病的诊断以及治疗效果的在体监测具有重要的帮助。

乙酰化透明质酸钠改善皮肤的功效

为研究乙酰化透明质酸钠(AcHA)改善皮肤的功效,以AcHA为原料,测试其对皮肤的保湿、修护、紧致、抗氧化性能。结果表明,AcHA累积渗透量为35.9%,性能良好;选用3D表皮皮肤模型,检测表皮皮肤模型的皮肤含水量和天然保湿因子含量的变化评估其保湿功效,观测表皮皮肤模型的组织形态、屏障相关蛋白含量和经表皮失水率的变化以评估其修护功效,研究表明体积分数0.25%的AcHA具有良好的保湿、修护、紧致以及抗氧化功效,为AcHA的进一步开发利用提供了理论基础。