-
Journal of Visualized Experiments : JoVE Jan 2020Biomedical optical imaging is playing an important role in diagnosis and treatment of various diseases. However, the accuracy and the reproducibility of an optical...
Biomedical optical imaging is playing an important role in diagnosis and treatment of various diseases. However, the accuracy and the reproducibility of an optical imaging device are greatly affected by the performance characteristics of its components, the test environment, and the operations. Therefore, it is necessary to calibrate these devices by traceable phantom standards. However, most of the currently available phantoms are homogeneous phantoms that cannot simulate multimodal and dynamic characteristics of biological tissue. Here, we show the fabrication of heterogeneous tissue-simulating phantoms using a production line integrating a spin coating module, a polyjet module, a fused deposition modeling (FDM) module, and an automatic control framework. The structural information and the optical parameters of a "digital optical phantom" are defined in a prototype file, imported to the production line, and fabricated layer-by-layer with sequential switch between different printing modalities. Technical capability of such a production line is exemplified by the automatic printing of skin-simulating phantoms that comprise the epidermis, dermis, subcutaneous tissue, and an embedded tumor.
Topics: Automation; Biomimetics; Computer Simulation; Computer-Aided Design; Dermis; Epidermis; Humans; Multimodal Imaging; Phantoms, Imaging; Printing, Three-Dimensional; Reproducibility of Results; Subcutaneous Tissue
PubMed: 31984957
DOI: 10.3791/60563 -
Journal of Cutaneous Pathology Feb 2016Lipomatous metaplasia is an uncommon phenomenon. After identifying the presence of a band of adipocytes in the superficial reticular dermis underlying two excisions for...
Lipomatous metaplasia is an uncommon phenomenon. After identifying the presence of a band of adipocytes in the superficial reticular dermis underlying two excisions for basal cell carcinoma, we prospectively reviewed all skin specimens accessioned in our laboratory over a 6-month period and identified eight additional cases. In each example there was a band of adipocytes in the upper dermis, at the level of solar elastosis that was widely separated from the subcutaneous fat by a normal appearing reticular dermis. The cells were positive for S100 and negative for CD163. No connection between the superficial band of adipocytes and the subcutaneous or periappendageal fat was seen. The alterations were flat in configuration without polypoid changes. Eyerich et al. reported lipomatous metaplasia in the dermis of a patient with acute generalized exanthematic pustulosis and psoriasis, and postulated this to be a postinflammatory phenomenon. Fatty metaplasia occurs within a variety of cutaneous neoplasms including nevi, adnexal tumors and peripheral nerve sheath tumors. However, superficial dermal fatty metaplasia beneath cutaneous neoplasms is a newly described phenomenon and we suspect this process represents fatty metaplasia within solar elastosis and that it may occur more frequently than recognized.
Topics: Adipocytes; Adult; Aged; Aged, 80 and over; Dermis; Female; Humans; Male; Metaplasia; Middle Aged; Skin Neoplasms
PubMed: 26443669
DOI: 10.1111/cup.12631 -
Skin Research and Technology : Official... Aug 2017Collagenous tissues store, transmit and dissipate elastic energy during mechanical deformation. In skin, mechanical energy is stored during loading and then is...
BACKGROUND
Collagenous tissues store, transmit and dissipate elastic energy during mechanical deformation. In skin, mechanical energy is stored during loading and then is dissipated, which protects skin from mechanical failure. Thus, energy storage (elastic properties) and dissipation (viscous properties) are important characteristics of extracellular matrices (ECMs) that support the cyclic loading of ECMs without tissue failure.
METHODS
Uniaxial stress-strain measurements on decellularized human dermis have been made and compared to results of a non-destructive technique involving optical coherence tomography (OCT) combined with vibrational analysis. In addition, Poisson's ratio has been determined for tensile deformation of decellularized dermis.
RESULTS
The modulus of decellularized dermis measured using standard tensile stress-strain tests and that determined from calculations derived from natural frequency measurements give similar results. It is also observed that Poisson's ratio for dermis is between 0.38 and 0.63 after correction for changes in volume that occur during tensile deformation. These results suggest that the assumption that dermis and other ECMs deform at constant volume is incorrect and will lead to differences in the calculated modulus by conventional tensile stress-strain measurements.
CONCLUSIONS
It is proposed that OCT in conjunction with vibrational analysis is a convenient way to non-destructively measure the modulus of decellularized dermis, ECMs and other materials that have a positive curvature to their stress-strain curves. Tensile deformation of dermis and possibly other ECMs is associated with an increase in Poisson's ratio consistent with a model of fluid expulsion from collagen fibrils during stretching. The value of Poisson's ratio should be considered in analyzing the mechanical properties of ECMs since at least dermis appears to be compressible during tensile deformation. Fluid expression during tensile deformation may play a role in mechanotransduction in skin in a similar manner to cartilage and bone tissue.
Topics: Collagen; Dermis; Elasticity; Extracellular Matrix; Humans; Mechanotransduction, Cellular; Models, Biological; Observational Studies as Topic; Poisson Distribution; Skin Physiological Phenomena; Stress, Mechanical; Tensile Strength; Tomography, Optical Coherence; Vibration; Viscosity
PubMed: 27891678
DOI: 10.1111/srt.12349 -
Wound Repair and Regeneration :... 2016Oral wounds heal faster and with better scar quality than skin wounds. Deep skin wounds where adipose tissue is exposed, have a greater risk of forming hypertrophic...
Oral wounds heal faster and with better scar quality than skin wounds. Deep skin wounds where adipose tissue is exposed, have a greater risk of forming hypertrophic scars. Differences in wound healing and final scar quality might be related to differences in mesenchymal stromal cells (MSC) and their ability to respond to intrinsic (autocrine) and extrinsic signals, such as human salivary histatin, epidermal growth factor, and transforming growth factor beta1. Dermis-, adipose-, and gingiva-derived MSC were compared for their regenerative potential with regards to proliferation, migration, and matrix contraction. Proliferation was assessed by cell counting and migration using a scratch wound assay. Matrix contraction and alpha smooth muscle actin was assessed in MSC populated collagen gels, and also in skin and gingival full thickness tissue engineered equivalents (reconstructed epithelium on MSC populated matrix). Compared to skin-derived MSC, gingiva MSC showed greater proliferation and migration capacity, and less matrix contraction in full thickness tissue equivalents, which may partly explain the superior oral wound healing. Epidermal keratinocytes were required for enhanced adipose MSC matrix contraction and alpha smooth muscle actin expression, and may therefore contribute to adverse scarring in deep cutaneous wounds. Histatin enhanced migration without influencing proliferation or matrix contraction in all three MSC, indicating that salivary peptides may have a beneficial effect on wound closure in general. Transforming growth factor beta1 enhanced contraction and alpha smooth muscle actin expression in all three MSC types when incorporated into collagen gels. Understanding the mechanisms responsible for the superior oral wound healing will aid us to develop advanced strategies for optimal skin regeneration, wound healing and scar formation.
Topics: Actins; Adipose Tissue; Cell Movement; Cell Proliferation; Dermis; Extracellular Matrix; Fibroblast Growth Factor 6; Gingiva; Humans; Keratinocytes; Mesenchymal Stem Cells; Regeneration; Wound Healing
PubMed: 26542883
DOI: 10.1111/wrr.12380 -
Biofabrication Nov 2018This study describes a perfusable and stretchable culture system for a skin-equivalent. The system is comprised of a flexible culture device equipped with connections...
This study describes a perfusable and stretchable culture system for a skin-equivalent. The system is comprised of a flexible culture device equipped with connections that fix vascular channels of the skin-equivalent and functions as an interface for an external pump. Furthermore, a stretching apparatus for the culture device can be fabricated using rapid prototyping technologies, which allows for easy modifications of stretching parameters. When cultured under dynamically stretching and perfusion conditions, the skin-equivalent exhibits improved morphology. The epidermal layer becomes thicker and more differentiated than that cultured without the stretching stimuli or under statically-stretched conditions, and the dermal layer was more densely populated with dermal fibroblasts than that cultured without perfusion due to the nutrient and oxygen supply by perfusion via the vascular channels. Therefore, the system is useful for the improvement and biological studies of skin-equivalents.
Topics: Bioprinting; Cell Culture Techniques; Cell Differentiation; Cells, Cultured; Dermis; Elasticity; Fibroblasts; Humans; Keratinocytes; Oxygen; Printing, Three-Dimensional; Skin
PubMed: 30431022
DOI: 10.1088/1758-5090/aaed12 -
Scientific Reports Jun 2021The skin barrier is provided by the organized multi-layer structure of epidermal cells, which is dynamically maintained by a continuous supply of cells from the basal...
The skin barrier is provided by the organized multi-layer structure of epidermal cells, which is dynamically maintained by a continuous supply of cells from the basal layer. The epidermal homeostasis can be disrupted by various skin diseases, which often cause morphological changes not only in the epidermis but in the dermis. We present a three-dimensional agent-based computational model of the epidermis that takes into account the deformability of the dermis. Our model can produce a stable epidermal structure with well-organized layers. We show that its stability depends on the cell supply rate from the basal layer. Modeling the morphological change of the dermis also enables us to investigate how the stiffness of the dermis affects the structure and barrier functions of the epidermis. Besides, we show that our model can simulate the formation of a corn (clavus) by assuming hyperproliferation and rapid differentiation. We also provide experimental data for human corn, which supports the model assumptions and the simulation result.
Topics: Computer Simulation; Dermis; Epidermis; Homeostasis; Humans; Skin Diseases
PubMed: 34168195
DOI: 10.1038/s41598-021-92540-1 -
Vaccine Jan 2020In the context of precision medicine and in response to the highly needed capacity of rapid interventions towards new infectious diseases and pandemic outbreaks,...
BACKGROUND
In the context of precision medicine and in response to the highly needed capacity of rapid interventions towards new infectious diseases and pandemic outbreaks, intradermal immunization is gaining increased attention. However, the currently used Mantoux technique for ID injection is difficult to standardize and requires training, especially when used in children. To allow determining the maximum penetration depth and needle characteristics for the development of a platform of medical devices suited for intradermal injection, VAX-ID® and to ensure an accurate ID injection in children, the epidermal and dermal thickness at the proximal ventral and dorsal forearm (PVF & PDF) and at the deltoid region in children aged 8 weeks to 18 years were assessed. The lateral part of the upper leg was assessed as well in children aged 8 weeks to 2 years since it is a commonly used injection site in this population.
MATERIALS & METHODS
Mean thickness of the PVF, PDF, lateral part of the upper leg and deltoid were measured using high-frequency ultrasound. Association with gender, age and BMI was assessed using Mann-Whitney U Test, Spearman correlation and Wilcoxon Signed Ranks Test, respectively.
RESULTS
Results showed an overall mean skin thickness of 0.99 mm (SD: 0.14 mm) at the PVF, 1.20 mm (SD: 0.17) at the PDF, 1.28 mm (SD: 0.16) at the lateral part of the upper leg and increasing to 1.32 mm (0.25) at the deltoid region. Age and BMI correlated significantly (p < 0.001) with skin thickness at all investigated body sites. Gender did not affect skin thickness in the investigated population.
CONCLUSION
Significant differences in skin thickness at the PVF, PDF and deltoid region were seen according to age and BMI. An optimal needle length of 0.7 mm is advised to guarantee intradermal injection in children at all investigated injection sites. (NCT02727114).
Topics: Adolescent; Age Factors; Body Mass Index; Child; Child, Preschool; Dermis; Epidermis; Female; Humans; Infant; Injections, Intradermal; Male; Needles; Sex Factors; Skin; Ultrasonography; Vaccination
PubMed: 31767463
DOI: 10.1016/j.vaccine.2019.11.002 -
Developmental Biology Nov 2019Salamanders are capable of full-thickness skin regeneration where removal of epidermis, dermis and hypodermis results in scar-free repair. What remains unclear is...
Salamanders are capable of full-thickness skin regeneration where removal of epidermis, dermis and hypodermis results in scar-free repair. What remains unclear is whether regeneration of these tissues recapitulates the cellular events of skin development or occurs through a process unique to regenerative healing. Unfortunately, information on the post-embryonic development of salamander skin is severely lacking, having focused on compartments or cell types, but never on the skin as a complete organ. By examining coordinated development of the epidermis and dermis in axolotls we establish six distinct stages of skin development (I-VI): I-V for normally paedomorphic adults and a sixth stage following metamorphosis. Raising animals either in isolation (zero density pressure) or in groups (density pressure) we find that skin development progresses as a function of animal size and that density directly effects developmental rate. Using keratins, p63, and proliferative markers, we show that when the dermis transforms into the stratum spongiosum and stratum compactum, keratinocytes differentiate into at least three distinct phenotypes that reveal a cryptic stratification program uncoupled from metamorphosis. Lastly, comparing skin regeneration to skin development, we find that dermal regeneration occurs through a unique process, relying heavily on remodeling of the wound extracellular matrix, rather than proceeding through direct development of a dermal lamella produced by the epidermis. By preventing fibroblast influx into the wound bed using beryllium nitrate, we show that in the absence of fibroblast generated ECM production skin regeneration occurs through an alternate route that recapitulates development.
Topics: Ambystoma mexicanum; Animals; Dermis; Embryonic Development; Epidermis; Extracellular Matrix; Fibroblasts; Keratinocytes; Keratins; Male; Regeneration; Signal Transduction; Skin; Time Factors; Wound Healing
PubMed: 31279726
DOI: 10.1016/j.ydbio.2019.07.001 -
Cell and Tissue Banking Sep 2015Many of the decellularised dermis products on the market at present are aspectically produced. NHS Blood and Transplant Tissue Services have developed a method of...
Many of the decellularised dermis products on the market at present are aspectically produced. NHS Blood and Transplant Tissue Services have developed a method of producing a dCELL human dermis which has been terminally sterilised by gamma irradiation. The terminally sterilised decellularised dermis was compared with cellular tissue and examined for histology, residual DNA content, biomechanical and biochemical properties, in vitro cytotoxicity and in vivo implantation in a mouse model. No alterations in morphology as viewed by light microscopy were observed and DNA removal was 99%. There were no significant changes in ultimate tensile stress or evidence for collagen denaturation or cytotoxicity. The in vivo studies did not indicate any adverse tissue reactions in the mouse model and demonstrated incorporation of dCELL human dermis into the host. Decellularisation, followed by terminal sterilisation with gamma irradiation, is an appropriate method to produce a human dermis allograft material suitable for transplantation.
Topics: Acellular Dermis; Animals; Collagen; Dermis; Elastic Modulus; Materials Testing; Mice; Sterilization; Tensile Strength; Tissue Engineering
PubMed: 25341645
DOI: 10.1007/s10561-014-9479-0 -
Tissue Engineering. Part C, Methods Apr 2015Porcine skin is commonly used as a model for human skin injury and as a source material for biologic scaffold materials. Although remarkable similarities between porcine...
Porcine skin is commonly used as a model for human skin injury and as a source material for biologic scaffold materials. Although remarkable similarities between porcine and human skin exist, regional anatomic variations present in human skin are also present in porcine skin. The objective of this study was to evaluate the structure of porcine skin from 11 different anatomic regions in the American Yorkshire crossbreed. Both qualitative and quantitative methods were used, with emphasis on epidermal and dermal thickness, hair follicle density, and collagen and elastin composition and distribution. The results showed that significant regional differences in skin histology exist, particularly with regard to the thickness of the dermis and epidermis and the amount of collagen and elastin within each tissue. Differences were also seen in the distribution of type I and type III collagen within the dermis. Therefore, while porcine skin shares many similarities with human skin, distinct regional differences in composition and morphology exist. This study highlights the importance of appreciating these regional differences to avoid misinterpretation of experimental results when using porcine skin as a human analogue.
Topics: Animals; Dermis; Epidermal Cells; Humans; Species Specificity; Swine
PubMed: 25205147
DOI: 10.1089/ten.TEC.2014.0246