Design of a Biomimetic Skin for an Octopus-Inspired Robot - Part Ⅰ: Characterising Octopus Skin

Octopus skin samples were tested under quasi-static and scissor cutting conditions to measure the in-plane material properties and fracture toughness. Samples from all eight arms of one octopus were tested statically to investigate how properties vary from arm to arm. Another nine octopus skins were measured to study the influence of body mass on skin properties. Influence of specimen location on skin mechanical properties was also studied. Material properties of skin, i.e. the Young's modulus, ultimate stress, failure strain and fracture toughness have been plotted against the position of skin along the length of arm or body. Statistical studies were carried out to help analyzing experimental data obtained. Results of this work will be used as guidelines for the design and development of artificial skins for an octopus-inspired robot.     

From Skin Cells to Ovarian Follicles?

Generating oocytes from cells derived from skin in vitro may provide a valuable modelfor identifying factors involved in germ cell formation and oocyte differentiation. In addition, the“oocytes” produced could potentially be useful for therapeutic cloning, and thus offer newpossibilities for tissue therapy. We recently reported the differentiation of cells derived fromporcine fetal skin into cells resembling germ cells and oocytes. A subpopulation of these cellsexpressed germ cell markers and formed aggregate like oocyte-cumulus complexes that secretedovarian steroid hormones and responded to gonadotropin stimulation. Some of these aggregatesextruded large oocyte-like cells that expressed markers appropriate to oocytes. We now showfurther evidence of germ cell marker expression during differentiation. We have also comparedthe oocyte-like cells with natural oocytes for their expression levels of Oct4, growthdifferentiation factor-9b (GDF9b), the deleted in azoospermia -like (DAZL) gene, vasa, zonapellucida (ZP), and the meiosis marker synaptonemal complex protein 3 (SCP3), and haverevealed interesting similarities and differences.     

Identification of Biomarkers of Human Skin Ageing in Both Genders. Wnt Signalling - A Label of Skin Ageing?

The goal of our work has been to investigate the mechanisms of gender-independent human skin ageing and examine the hypothesis of skin being an adequate model of global ageing. For this purpose, whole genome gene profiling was employed in sun-protected skin obtained from European Caucasian young and elderly females (mean age 26.7±4 years [n1 = 7] and 70.75±3.3 years [n2 = 4], respectively) and males (mean age 25.8±5.2 years [n3 = 6] and 76±3.8 years [n4 = 7], respectively) using the Illumina array platform. Confirmation of gene regulation was performed by real-time RT-PCR and immunohistochemistry. 523 genes were significantly regulated in female skin and 401 genes in male skin for the chosen criteria. Of these, 183 genes exhibited increased and 340 decreased expression in females whereas 210 genes showed increased and 191 decreased expression in males with age. In total, 39 genes were common in the target lists of significant regulated genes in males and females. 35 of these genes showed increased (16) or decreased (19) expression independent of gender. Only 4 overlapping genes (OR52N2, F6FR1OP2, TUBAL3 and STK40) showed differential regulation with age. Interestingly, Wnt signalling pathway showed to be significantly downregulated in aged skin with decreased gene and protein expression for males and females, accordingly. In addition, several genes involved in central nervous system (CNS) ageing (f.i. APP, TAU) showed to be expressed in human skin and were significanlty regulated with age. In conclusion, our study provides biomarkers of endogenous human skin ageing in both genders and highlight the role of Wnt signalling in this process. Furthermore, our data give evidence that skin could be used as a good alternative to understand ageing of different tissues such as CNS.     

Shelf-Life Evaluation of Bilayered Human Skin Equivalent, MyDerm™

Skin plays an important role in defense against infection and other harmful biological agents. Due to its fragile structure, skin can be easily damaged by heat, chemicals, traumatic injuries and diseases. An autologous bilayered human skin equivalent, MyDerm™, was engineered to provide a living skin substitute to treat critical skin loss. However, one of the disadvantages of living skin substitute is its short shelf-life, hence limiting its distribution worldwide. The aim of this study was to evaluate the shelf-life of MyDerm™ through assessment of cell morphology, cell viability, population doubling time and functional gene expression levels before transplantation. Skin samples were digested with 0.6% Collagenase Type I followed by epithelial cells dissociation with TrypLE Select. Dermal fibroblasts and keratinocytes were culture-expanded to obtain sufficient cells for MyDerm™ construction. MyDerm™ was constructed with plasma-fibrin as temporary biomaterial and evaluated at 0, 24, 48 and 72 hours after storage at 4°C for its shelf-life determination. The morphology of skin cells derived from MyDerm™ remained unchanged across storage times. Cells harvested from MyDerm™ after storage appeared in good viability (90.5%±2.7% to 94.9%±1.6%) and had short population doubling time (58.4±8.7 to 76.9±19 hours). The modest drop in cell viability and increased in population doubling time at longer storage duration did not demonstrate a significant difference. Gene expression for CK10, CK14 and COL III were also comparable between different storage times. In conclusion, MyDerm™ can be stored in basal medium at 4°C for at least 72 hours before transplantation without compromising its functionality.     

Skin and diabetes mellitus: what do we know?

Diabetes mellitus (DM) is becoming increasingly prevalent worldwide. Although major complications of this condition involve kidney, retina and peripheral nerves, the skin of diabetic patients is also frequently injured. Hence, interest is mounting in the definition of the structural and molecular profile of non-complicated diabetic skin, i.e., before injuries occur. Most of the available knowledge in this area has been obtained relatively recently and, in part, derives from various diabetic animal models. These include both insulin-dependent and insulin-resistant models. Structural work in human diabetic skin has also been carried out by means of tissue samples or of non-invasive methods. Indications have indeed been found for molecular/structural changes in diabetic skin. However, the overall picture that emerges is heterogeneous, incomplete and often contradictory and many questions remain unanswered. This review aims to detail, as much as possible, the various pieces of current knowledge in a systematic and synoptic manner. This should aid the identification of areas in which key questions are still open and more research is needed. A comprehensive understanding of this field could help in determining molecular targets for the prevention and treatment of skin injuries in DM and markers for the monitoring of cutaneous and systemic aspects of the disease. Additionally, with the increasing development of non-invasive optics-based deep-tissue-imaging diagnostic technologies, precise knowledge of cutaneous texture and molecular structure becomes an important pre-requisite for the use of such methods in diabetic patients.     

Resistin-like Molecule α Provides Vitamin-A-Dependent Antimicrobial Protection in the Skin

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Skin aging: a role for telomerase and telomere dynamics?

Skin is a complex tissue composed of two very different compartments -- the continuously renewing epidermis made up mostly by keratinocytes and the underlying matrix-rich dermis with the resting fibroblasts as its major cellular components. Both compartments are tightly interconnected and a paracrine mutual interaction is essential for epidermal growth, differentiation, and tissue homeostasis. Skin aging is commonly viewed as wrinkle formation, hair greying, and impaired wound healing. Nevertheless, the epidermis as the outermost shield needs to remain intact in order to guarantee an inside-out and outside-in barrier function throughout life time of a human being. Furthermore, the epidermis is one of the few regenerative tissues that express telomerase, the ribonucleoprotein complex that can counteract telomere erosion, one of the presently mostly favoured potential mechanisms causing cellular aging. This raises the question whether in the epidermis telomerase is able to counteract telomere erosion and thereby to prevents a telomere-dependent aging process and consequently which part of the skin is responsible for the most obvious changes associated with skin aging.     

FOOD HYPERSENSITIVITY—Correlation of Intradermal Skin Tests with Clinical Allergenicity

A study was made to determine how well the results of skin tests for sensitivity to various foods agreed with observation of clinical reactions to those foods.Test reactions were divided into several categories—negative, and 1, 2, 3 or 4 plus. Then the strong reactions, that is the 3 and 4 plus reactions, the milder reactions and the negative results were studied separately to determine the agreement of results, in each category, with the clinical response. Wide variations were noted. For some foods the agreement was high, for others low. For some foods, the agreement was high in some categories of reaction, low in others. For example, negative results of skin test might match with nonreaction to the food clinically in a high proportion of cases, and 3 or 4 plus reaction to skin test might be in close agreement with the incidence of distress upon ingestion of the food, yet for the same food there might be very poor correlation between mild reaction to skin test and clinical response. This being the case, accuracy of skin tests cannot be determined simply by combining all data on reactions, of whatever degree, and taking the aggregate of agreement in all categories as an index of the validity of the test. Each category of reaction must be considered separately.Combined data and categorized data on accuracy of skin tests for sensitivity to 26 foods were tabulated in the present study.     

Tanning Devices – Fast Track to Skin Cancer?

The use of UVB and/or UVA emitting devices for cosmetic tanning is widespread in Western populations including young people and is especially prevalent in females. Several epidemiological studies, although not all, have shown a significant relationship between the use of tanning devices and malignant melanoma after, in some cases, adjustment for confounding factors such as solar ultraviolet radiation (UVR) exposure. A relationship between solar exposure, especially intermittent exposure, and malignant melanoma is well established so it is not surprising that a similar connection has been reported for the use of tanning devices. Several epidemiological studies show that childhood exposure to sunlight is a risk factor for malignant melanoma and this may also be the case for the use of tanning devices, especially if sunburns are obtained. Some studies have evaluated the relationship between the use of tanning devices and non‐melanoma skin cancer and at least one has suggested an association. The use of tanning devices by a substantial minority of young people is a worrying trend in terms of a likely increased incidence of malignant melanoma, and possibly non‐melanoma cancers in the future. Although two recent reviews by epidemiologists conclude that a clear link between tanning devices and malignant melanoma is yet to be proven, there is a strong case for effective legislation to prohibit the use of tanning devices by people under 18 yr of age.     

The Sandfish＇s Skin： Morphology, Chemistry and Reconstruction

The sandfish is a lizard having the remarkable ability to move in desert sand in a swimming-like fashion. The most outstanding adaptations to this mode of life are the low friction behaviour and the extensive abrasion resistance of the sandfish skin against sand, outperforming even steel. We investigated the topography, the composition and the mechanical properties of sandfish scales. These consist of glycosylated keratins with high amount of sulphur but no hard inorganic material, such as silicates or lime. Remarkably, atomic force microscopy shows an almost complete absence of attractive forces between the scale surface and a silicon tip, suggesting that this is responsible for the unusual tribological properties. The unusual glycosylation of the keratins was found to be absolutely necessary for the described phenomenon. The scales were dissolved and reconstituted on a polymer surface resulting in properties similar to the original scale. Thus, we provide a pathway towards exploitation of the reconstituted scale material for future engineering applications.     

Skin extracellular matrix components accelerate the regenerative potential of Lin− cells

Due to their unique properties, bone marrow-derived Lin^? cells can be used to regenerate damaged tissues, including skin. The objective of our study was to determine the influence of the skin tissue-specific microenvironment on mouse Lin^? cell proliferation and migration in vitro. Cells were analyzed for the expression of stem/progenitor surface markers by flow cytometry. Proliferation of MACS-purified cells in 3D cultures was investigated by WST-8 assay. Lin^? cell migration was evaluated by in vitro scratch assay. The results obtained show that basement membrane matrix is more effective for Lin^? cell proliferation in vitro. However, type I collagen matrix better enhances the re-epithelization process, that depends on the cell migratory properties. These studies are important for preparing cells to be used in transplantation.     

Error-Prone Replication through UV Lesions by DNA Polymerase θ Protects against Skin Cancers

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