Artificial Skin Model Research Articles

Development and Validation of an Artificial Mechanical Skin Model for the Study of Interactions between Skin and Microneedles

Microneedles are small needle‐like structures that are almost invisible to the naked eye. They have an immense potential to serve as a valuable tool in many medical applications, such as painless vaccination. Microneedles work by breaking through the stratum corneum, the outermost barrier layer of the skin, and providing a direct path for drug delivery into the skin. A lot of research has been presented over the past two decades on the applications of microneedles, yet the fundamental mechanism of how they interact, pressure, and penetrate the skin in its native state is worth examining further. As such, a major difficulty with understanding the mechanism of microneedle–skin interaction is the lack of an artificial mechanical human skin model to use as a standardized substrate. In this research news, the development of an artificial mechanical skin model based on a thorough mechanical study of fresh human and porcine skin samples is presented. The artificial mechanical skin model can be used to study the mechanical interactions between microneedles and skin, but not diffusion of molecules across skin. This model can assist in improving the performance of microneedles by enhancing the reproducibility of microneedle depth insertions for optimal drug delivery and biosensing. image

The depigmenting effect and mechanism S of Kuwanon O and Sanggenon T from the roots of Morus australi

Kuwanon O and sanggenon T, two resorcinol-type polyphenols from the root extract of Morus australis, were found to reveal significant depigmenting effects in both murine b16f10 and melan-a cell lines. But their depigmenting mechanisms are slightly different in two cell systems. In b16 cells, kuwanon O and sanggenon T, together with other two phenolics, induced post-transcriptional degradations of MITF without suppressing its mRNA expression, leading to significant decreases of TRP-1 and TRP-2 production. While in melan-a cells, the levels of tyrosinase families were suppressed via MITF downregulation at both transcription and translation level by them, with kuwanon O inducing the greatest suppression. Further evaluations in artificial skin model demonstrated the outstanding depigmenting effects of kuwanon O and sanggenon T. Meanwhile, according to the structure-activity relationship study of theses compounds, to screen or synthesize resorcinol flavonone derivatives with isoprenyl group in the Diels-Alder substituent might be a new direction for the search of potent hypopigmenting agents

Oxyresveratrol and trans-dihydromorin from the twigs of Cudrania tricuspidata as hypopigmenting agents against melanogenesis

The depigmenting effects of oxyresveratrol and trans-dihydromorin were investigated in b16F10 cell line and its synergetic melan-a cells, as well as in 3-dimensional skin models. But their inhibitory effects were different in two cell lines. In b16 cells, oxyresveratrol showed stronger depigmenting effect than trans-dihydromorin, with greater suppression on tyrosinase activity. Both of them induced post-transcriptional degradations of microphthalmia-associated transcription factor (MITF), leading to significant decreases of tyrosinase related protein 1 (TRP-1) and tyrosinase related protein 2 (TRP-2) production. In melan-a cells, trans-dihydromorin exhibited stronger inhibition on melanin synthesis. It also induced greater suppression on the levels of tyrosinase, TRP-1 and TRP-2 via MITF down-regulation at both transcription and translation level. Evaluations in artificial skin model also demonstrated the depigmenting effects of trans-dihydromorin. In conclusion, we found that trans-dihydromorin is an effective hypopigmenting agent in normal skin cells. Furthermore we demonstrated that hypopigmenting agents effective in melanoma system may not be effective on normal melanocytes, indicating that a non-tumor melanocyte system is more suitable for the screening of hypopigmenting agents.

引っ掻き音計測による引っ掻き動作評価に関する研究

Itch is an unpleasant sensation associated with various disease, and can trigger scratching. Management of itch and scratching is important for treatment of disease. Therefore, quantitative and objective evaluation of itch and scratching is demanded. This work aims to develop the sensor system for evaluating the scratching motion. For the purpose, we focus on scratch sounds induced by scratching motion and, propose a nail mounted sensor system . In the sensor system a small microphone is attached on a nail for measuring scratching sounds. First, for investigating the relationship between the scratch sounds and the mechanical characteristics of human scratch motion, the artificial skin model made of polyurethane was used as a scratched object. The measurement system that can measure force and a motion of fingertip during scratching was constructed. Using the measurement system, various kinds of human scratch motions and sounds were measured. By signal processing of the scratch sounds, the several sound features were calculated and characteristics of scratch motions were extracted. Then, correlation coefficients between sound features and scratch motion properties were calculated. From the results, two pairs of the parameters were found as the most adequate parameter pair to evaluate the mechanical characteristics of human scratch motion. And using these parameters, “scratch evaluation map” was proposed as a method to evaluate the mechanical characteristics of human scratch motion. From the results, it was found that the developed sensor system has possibility to evaluate the mechanical characteristics of human scratch motion by the scratch sounds.

Superhydrophobicity-Enabled Interfacial Microfluidics on Textile

ABSTRACTCapillary-driven microfluidics, utilizes the capillary force generated by fibrous hydrophilic materials (e.g., paper and cotton) to drive biological reagents, has been extended to various biological and chemical analyses recently. However, the restricted capillary-driving mechanism persists to be a major challenge for continuous and facilitated biofluidic transport. In this abstract, we have first introduced a new interfacial microfluidic transport principle to automatically and continuously drive three-dimensional liquid flows on a micropatterned superhydrophobic textile (MST). Specifically, the MST platform utilizes the surface tension-induced Laplace pressure to facilitate the liquid motion along the fibers, in addition to the capillary force existing in the fibrous structure. The surface tension-induced pressure can be highly controllable by the sizes of the stitching patterns of hydrophilic yarns and the confined liquid volume. Moreover, the fluidic resistances of various configurations of connecting fibers are quantitatively investigated. Furthermore, a demonstration of the liquid collection ability of MST has been demonstrated on an artificial skin model. The MST can be potentially applied to large volume and continuous biofluidic collection and removal.

A comparison of Raman, FTIR and ATR-FTIR micro spectroscopy for imaging human skin tissue sections

Raman and infrared absorption spectroscopies are compared for the analysis of human hand skin tissue sections. The tissue sections have been formalin fixed and paraffin processed, and subsequently dewaxed. Fourier Transform Infrared (FTIR) spectra are preprocessed using the resonant Mie-extended multiplicative scattering algorithm to remove spectral artefacts. FTIR images of resolution 4 cm−1, analysed using K-means cluster analysis, reveal the double layer structure of the dermis and epidermis, but no further layer differentiation is achieved using the higher spatial resolution of the Attenuated Total Reflection imaging or improved spectral resolution of 2 cm−1. At comparable spectral and spatial resolutions and measurement on the same samples, Raman scattering produces spectra of significantly higher spectral detail and can differentiate the stratum corneum from the underlying epithelial layer, and, in the absence of melanin in an artificial skin model, can further differentiate the basal layer from the overlying epithelium. The differences in the performance of the techniques are therefore not instrumentational and are discussed in terms of the technological and fundamental differences between the two complementary techniques.

Raman spectroscopic mapping for the analysis of solar radiation induced skin damage

The effects of simulated solar irradiation of an artificial skin model have been examined using Raman spectroscopy and the results are compared with cytotoxicological and histological profiling. Samples exposed for times varying between 30 minutes and 240 minutes were incubated post exposure for a period of 96 hours. The cytotoxicological response as measured by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay demonstrated a ~50% loss of viability of the artificial tissue after 120 minutes exposure. Histological staining of tissue sections showed considerable loss of cellular content in the epidermal layer at this endpoint. Raman spectroscopic mapping of tissue sections, coupled with K-means cluster analysis (KMCA) clearly identified the dermal and stratum corneum layers and differentiated further substructures of the epidermis. Post irradiation, a significant loss of DNA features in the basal layer was apparent in the results of the KMCA. Principal Components Analysis (PCA) of layers identified by the KMCA post exposure compared with controls indicated a significant increase in the lipidic signatures of the stratum corneum. In the dermal layer, little photodamage was observed, but a similar increase in lipidic signatures in the basal layer was accompanied by a decrease in DNA and protein contributions. The spectral profiles of the photodamage to the basal layer as identified by PCA are consistent over the exposure periods of 30-240 minutes, but an examination of the evolution of features associated with specific biochemical components indicated DNA damage and loss of lipidic signatures at the early exposure times, whereas changes in protein signatures appeared to evolve over longer periods. In comparison to the cytotoxicological responses, the study demonstrates that Raman spectroscopy can identify biochemical changes as a result of solar exposure at time points significantly earlier than changes in tissue viability are observed.

Proteasome inhibition and ROS generation by 4‐nerolidylcatechol induces melanoma cell death

Induction of apoptotic cell death in response to chemotherapy and other external stimuli has proved extremely difficult in melanoma, leading to tumor progression, metastasis formation and resistance to therapy. A promising approach for cancer chemotherapy is the inhibition of proteasomal activity, as the half-life of the majority of cellular proteins is under proteasomal control and inhibitors have been shown to induce cell death programs in a wide variety of tumor cell types. 4-Nerolidylcatechol (4-NC) is a potent antioxidant whose cytotoxic potential has already been demonstrated in melanoma tumor cell lines. Furthermore, 4-NC was able to induce the accumulation of ubiquitinated proteins, including classic targets of this process such as Mcl-1. As shown for other proteasomal inhibitors in melanoma, the cytotoxic action of 4-NC is time-dependent upon the pro-apoptotic protein Noxa, which is able to bind and neutralize Mcl-1. We demonstrate the role of 4-NC as a potent inducer of ROS and p53. The use of an artificial skin model containing melanoma also provided evidence that 4-NC prevented melanoma proliferation in a 3D model that more closely resembles normal human skin.

The Use of an Artificial Skin Model to Study Transdermal Absorption of Drugs in Inflamed Skin

Studies on drug disposition in inflamed skin are important for safe and effective application of topical drugs. Here, the absorption of flurbiprofen (FP) through inflamed skin was examined in vivo and in a skin-mimicking artificial model system. The model skin system consisted of a silicone membrane acting as a model stratum corneum, laminated dialysis membranes acting as a model of viable skin, and 2 microdialysis probes-one used for determination of FP concentration and one acting as a model vessel. This model system could be used for quantitative evaluation of complicated permeation processes. In the in vivo experiments, FP absorption was suppressed in rats with inflamed skin induced by an intracutaneous injection of a mixed solution of λ-carrageenan, zymosan, and casein. Bovine serum albumin solution was placed between the dialysis membranes in the model skin system to mimic protein leaching in skin; the results suggested that the delayed absorption of FP in inflamed skin was due to binding to serum proteins leaching in the tissue. Such a combination of in vivo experiments and a model skin system is useful for understanding complex phenomena in inflamed and damaged skin and reduces experimental animal use.

Study of a Drug Interaction Involving the Permeation Process Using an Artificial Skin Model as an Alternative to Animal Skin

Study of a Drug Interaction Involving the Permeation Process Using an Artificial Skin Model as an Alternative to Animal Skin

The fibroblast-derived paracrine factor neuregulin-1 has a novel role in regulating the constitutive color and melanocyte function in human skin

Interactions between melanocytes and neighboring cells in the skin are important in regulating skin color in humans. We recently demonstrated that the less pigmented and thicker skin on the palms and soles is regulated by underlying fibroblasts in those areas, specifically via a secreted factor (DKK1) that modulates Wnt signaling. In this study, we tested the hypothesis that dermal fibroblasts regulate the constitutive skin color of individuals ranging from very light to very dark. We used microarray analysis to compare gene expression patterns in fibroblasts derived from lighter skin types compared to darker skin types, with a focus on secreted proteins. We identified a number of genes that differ dramatically in expression and, among the expressed proteins, neuregulin-1, which is secreted by fibroblasts derived from dark skin, effectively increases the pigmentation of melanocytes in tissue culture and in an artificial skin model and regulates their growth, suggesting that it is one of the major factors determining human skin color.

Development of a method for assessing non-targeted radiation damage in an artificial 3D human skin model

Purpose: Despite the increasing concern about the effect of doses below 0.5 Gy and non-targeted exposures of ionising radiation on living organisms, the majority of radiobiological studies are conducted using in vitro cell lines. In order to be able to extrapolate the in vitro results to in vivo models with confidence, it would be of great benefit to develop a reproducible tissue system suitable for critical radiobiological assays. This manuscript describes the development of a reliable protocol to harvest cells from tissue samples and investigate the radiation damage induced on a single cell basis.Materials and methods: To validate this approach as a potential tool for bystander experiments, the method focuses on analysing radiation damage in individual cells as a function of their relative position in the tissue. The experiments reported describe the micronucleus formation following partial irradiation with 3.5 MeV protons (0.1, 0.5 and 1 Gy) in an artificial human skin construct.Results: The reproducible and low background frequency of micronuclei measured in this system allows detection of small increases following radiation exposures. The effect was statistically significant at doses as low as 0.1 Gy in the directly irradiated as well as in the bystander cells.Conclusions: The data presented provide evidence of a spatially dependent bystander effect whose magnitude decrease as a function of the distance from the directly exposed area.

Rat epidermal keratinocyte organotypic culture (ROC) compared to human cadaver skin: The effect of skin permeation enhancers

The objective of this study was to evaluate the response of the rat epidermal keratinocyte organotypic culture (ROC) to permeation enhancers, and to compare these responses to those in human cadaver skin. Different concentrations of two mixtures for enhancing permeation were investigated, sodium dodecyl sulfate:phenyl piperazine and methyl pyrrolidone:dodecyl pyridinium chloride, using skin impedance spectroscopy and two experimental compounds, the lipophilic corticosterone and the hydrophilic sucrose. The chemical irritation effects of the formulations were evaluated based on leakage of lactate dehydrogenase enzyme (LDH) and cellular morphological perturbation. This study provides evidence for direct correlations of permeation/permeation, impedance/impedance and permation/impedance between the culture model and human skin. The only exception was the enhancer induced permeation of sucrose which was 1–40-fold higher in ROC compared to human skin, reflecting the more disordered lipid organization in stratum corneum and consequently the greater number of polar pathways. LDH leakage and cellular morphology indicated that it was possible to differentiate between safe permeation enhancers from irritating agents. This is not only the first study to have compared the enhancer effects on a cultured skin model with human skin, but also it has demonstrated enhancer induced irritation using an artificial skin model.

Clinical Results of an Autologous Engineered Skin

An artificial complete skin (dermis and epidermis) model has been developed in the Tissue engineering unit of the Centro Comunitario de Sangre y Tejidos del Principado de Asturias (CCST) and CIEMAT. This engineered skin has been employed for the treatment of severe epithelial injuries. In this paper, the clinical results obtained with this engineered skin during the last 18 months were evaluated. (a) Culture: Cells (fibroblasts and keratinocytes) were obtained from biopsies by a double enzymatic digestion. After an expansion period, fibroblasts were seeded in an artificial dermis based on human plasma. Keratinocytes were seeded over this dermal surface. (b) 20 skin biopsies were processed (13 burned patients, 5 giant nevus, 1 GVHD, 1 neurofibromatosis), which came from different hospitals across the country. About 97,525 cm(2) of engineered skin were cultured. The engineered skin took in all patients. The take percentage depended on previous pathology (burned patients 10-90%; non-critical patients 70-90%). The epithelization obtained was permanent in all cases. During the follow-up period, epithelial loss, blistering injuries or skin retractions were not observed. The aesthetic and functional results were acceptable. This artificial skin has demonstrated to be useful for the definitive treatment of patients with severe skin injuries. This work shows that it is possible to produce this prototype in an hospitalarian laboratory and distribute it to different hospitals across the country.

Priority claims for surgical techniques

To the Editor: In “Surgical Pearl: Artificial skin model for simulation of flap mechanics,” Garcia et al1Garcia C. Haque R. Poletti E. Surgical pearl: artificial skin model for simulation of flap mechanics.J Am Acad Dermatol. 2005; 53: 143-144Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar demonstrate a way to simulate flap movement. Although clever, this is not novel; in fact, a very similar approach has been both published2Lewis L.A. Nusbaum B.P. VaraDerm: a skin substitute for surgical workshops.J Dermatol Surg Oncol. 1987; 13: 473-474Crossref PubMed Scopus (5) Google Scholar and patented.3Lewis LA, Nusbaum BP, Leeds HR. US Patent 4,596,528. June 24, 1986. Simulated skin and method. Available at: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=4,596,528.WKU.&OS=PN/4,596,528&RS=PN/4,596,528. Accessed November 28, 2005.Google Scholar In essence, the publication makes an indirect false priority claim by failing to cite directly pertinent prior work. In recent issues of this journal, there have been a number of letters discussing firstness, firstedness, and false firstedness with examples of erroneous claims and scenarios of unintentional false claims.4Summers J.B. Journalology and citation etiquette: firstedness might matter, but only if you're really first!.J Am Acad Dermatol. 2003; 48 (author reply 310): 309-310Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar, 5Summers J.B. Kaminski J.M. False firstedness: the dilemma of priority claims in biomedical publications.J Am Acad Dermatol. 2005; 52: 735-736Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar, 6Barankin B. False firstedness.J Am Acad Dermatol. 2005; 53: 367-368Abstract Full Text Full Text PDF PubMed Scopus (3) Google Scholar, 7Cropley T.G. Bernhard J.D. Another first.J Am Acad Dermatol. 2005; 53: 368Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar As the number of global medical journals, online journals, Internet chat rooms, and listservs increase, it becomes more difficult for an author to make priority or firstness claims. It all depends on sleuthing skills and thoroughness to identify previously published work and inventions online and offline. The Internet is an invaluable resource for the savvy user to dig out both old and new information about almost any product, technique, or invention. We believe that in contrast to medical or research articles, authors of Surgical Pearls who think they have invented a technique do not realize they need to search for precedents, do not know how, or do not realize how simple it is to do. A simple search via PUBMED using the search terms “skin substitute” or “skin surgery teaching” would have identified preceding descriptions of the approach. There are many different methods of searching, using multiple search engines, and using Boolean logic to narrow the search and locate information. Sites such as www.searchbug.com allow users to link to many other focused search engines; www.archive.org allows users to find World Wide Web sites that are no longer in existence. Meta-search engines such as www.dogpile.com and www.mamma.com allow users to search many search engines simultaneously. The World Wide Web site www.soople.com, which simplifies advanced searches, is the “Google for Dummies,” as it allows Boolean searches without the need for understanding Boolean principles. Perhaps we are the first to suspect that authors who report on what they believe are new surgical techniques may not realize that a search for prior work can and should be achieved through a variety of search techniques, and that this is important whether a claim of firstness is being made or not. Even when no such direct claim is made, failure to identify earlier work may lead to an indirect first priority claim, perhaps a new concept, but we are cautious and scared enough not to commit the false firstedness fallacy here.4Summers J.B. Journalology and citation etiquette: firstedness might matter, but only if you're really first!.J Am Acad Dermatol. 2003; 48 (author reply 310): 309-310Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar

Surgical Pearl: Artificial skin model for simulation of flap mechanics

Cadaveric skin and currently available artificial skin models are not suitable for performance of skin flaps. They do not accurately resemble the elastic nature of skin while maintaining an underlying component of tension that increases proportionately to force applied. We have developed a simple model to manipulate flaps three-dimensionally and then secure them in place with either sutures or staples. A superimposed grid pattern clearly portrays the movement of tissue and the concomitant force vectors produced.

Effect of the 1,450 nm diode non-ablative laser on collagen expression in an artificial skin model

The 1,450-nm Smoothbeam Laser is a diode laser equipped with a cryogen cooling spray. Primary objectives were to evaluate the effects of this non-ablative laser on Apligraf (bioengineered skin-substitute) and to document its use as a model for non-ablative procedures. We also measured the effects of laser fluence levels on collagen and elastin expression. Three sheets of Apligraf were used for this study. Each received six separate laser applications at 4J, 6J, 8J, 10 J, 12J, and 14J. The sheets were then incubated with 10% CO(2) at 37 degrees C and samples were collected and analyzed 3 days later, using RT-PCR and immunofluorescent staining. Collagen III expressions significantly increased in both mRNA and protein levels at approximately 12 J. There appears to be a threshold effect where there is very little increased collagen III mRNA and protein expression until the laser fluence reaches around 12J.

Optical coherence tomography for in vitro monitoring of wound healing after laser irradiation

We demonstrate a novel application of optical coherence tomography (OCT) to monitor post-laser irradiation collagen injury in model skin. An artificial skin model (RAFT), which closely approximates human skin, was irradiated with a Perovskite laser (/spl lambda/=1341 nm), which is under investigation for potential use as a nonablative laser skin rejuvenation device (NALSR). OCT was used to determine the extent of laser injury immediately post irradiation and, subsequently, to monitor tissue recovery over a seven-day period. OCT images clearly delineated areas of post-irradiation collagen injury and allowed noninvasive monitoring of the wound healing process. Histology was used for comparison and correlated well with OCT images. OCT offers advantages over standard histology as it is noninvasive and allows serial monitoring at the same site over time. Our results indicate that OCT has potential as a method for characterization of collagen injury post-laser irradiation and may be a useful tool for determination of optimal parameters for NALSR using different devices under investigation for this indication.

Evaluation of the cytotoxic effects of bis-quaternary ammonium antimicrobial reagents on human cells

The cytotoxic effects of newly synthesized bis-quaternary ammonium compounds (bis-QACs) and benzalkonium chloride were investigated on skin and blood cells, namely normal human epidermal keratinocytes of neonatal foreskin, a normal human skin fibroblast cell line NB1RGB, erythrocytes and a lymphoma cell line JM. The bis-QACs tested were 4,4′-(1,6-hexamethylenedithio)bis(1-octylpyridinium iodide) (4DTBP-6,8), N, N′-tetramethylenebis(1-dodecyl-4-carbamoylpyridinium iodide) (4BCAP-4,12), N, N′-hexamethylenebis(1-decyl-4-carbamoylpyridinium iodide) (4BCAP-6,10), 4,4′-(1,4-tetramethylenedicarbonyldiamine) bis (1-decylpyridinium iodide) (4DCABP-4,10), 4,4′-(1,4-tetramethylenedicarbonyldiamine) bis (1-dodecylpyridinium iodide) (4DCABP-4,12), 4,4′-(1,4-phenyldicarbonyldiamine)bis(1-dodecylpyridinium iodide) (4DCABP-P,12), and 4,4′-(1,6-hexamethylenedioxydicarbonyl)bis(1-dodecylpyridinium iodide) (4DOCBP-6,12). All bis-QACs consisted of two identical alkylpyridinium rings and bridge structure linking rings to each other have a methylene bridge but only 4DCABP-P,12 has a phenyl ring as a bridge. Most of the LD 50 values in acute cytotoxic assays of these bis-QACs tended to be lower than those of benzalkonium chloride. However, the comparison of the antibacterial activity against cytotoxic effects on several human cells revealed that bis-QACs, especially 4DTBP-6,8, have wide concentration ranges showing sufficient antibacterial activity and lower cytotoxic effect on human cells (except for 4DOCBP-6,12), although benzalkonium chloride caused significant human cell damage at the concentrations necessary for antibacterial activity. Moreover, judging from the LD 50 value of 4DTBP-6,8 [67 μ m, a 6.7-fold higher concentration than the upper value of MIC] obtained in an artificial human skin model TESTSKIN, 4DTBP-6,8 is thought to be a more effective and safer antiseptic reagent for application to the skin surface than benzalkonium chloride. Taken together, bis-QACs are expected to be a promising new generation of antimicrobial QACs.

Flexibilized gelatin film based on an artificial skin model, III

Flexibilized gelatin film based on an artificial skin model, III