TY - JOUR A1 - Brendtke, Rico A1 - Wiehl, Michael A1 - Groeber, Florian A1 - Schwarz, Thomas A1 - Walles, Heike A1 - Hansmann, Jan T1 - Feasibility Study on a Microwave-Based Sensor for Measuring Hydration Level Using Human Skin Models JF - PLoS ONE N2 - Tissue dehydration results in three major types of exsiccosis—hyper-, hypo-, or isonatraemia. All three types entail alterations of salt concentrations leading to impaired biochemical processes, and can finally cause severe morbidity. The aim of our study was to demonstrate the feasibility of a microwave-based sensor technology for the non-invasive measurement of the hydration status. Electromagnetic waves at high frequencies interact with molecules, especially water. Hence, if a sample contains free water molecules, this can be detected in a reflected microwave signal. To develop the sensor system, human three-dimensional skin equivalents were instituted as a standardized test platform mimicking reproducible exsiccosis scenarios. Therefore, skin equivalents with a specific hydration and density of matrix components were generated and microwave measurements were performed. Hydration-specific spectra allowed deriving the hydration state of the skin models. A further advantage of the skin equivalents was the characterization of the impact of distinct skin components on the measured signals to investigate mechanisms of signal generation. The results demonstrate the feasibility of a non-invasive microwave-based hydration sensor technology. The sensor bears potential to be integrated in a wearable medical device for personal health monitoring. KW - gels KW - microwave radiation KW - collagens KW - skin physiology KW - reflection KW - skin anatomy KW - epidermis KW - antennas Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-179934 VL - 11 IS - 4 ER - TY - JOUR A1 - Groeber, Florian A1 - Engelhardt, Lisa A1 - Lange, Julia A1 - Kurdyn, Szymon A1 - Schmid, Freia F. A1 - Rücker, Christoph A1 - Mielke, Stephan A1 - Walles, Heike A1 - Hansmann, Jan T1 - A First Vascularized Skin Equivalent as an Alternative to Animal Experimentation JF - ALTEX - Alternatives to Animal Experimentation N2 - Tissue-engineered skin equivalents mimic key aspects of the human skin, and can thus be employed as wound coverage for large skin defects or as in vitro test systems as an alternative to animal models. However, current skin equivalents lack a functional vasculature limiting clinical and research applications. This study demonstrates the generation of a vascularized skin equivalent with a perfused vascular network by combining a biological vascularized scaffold (BioVaSc) based on a decellularized segment of a porcine jejunum and a tailored bioreactor system. Briefly, the BioVaSc was seeded with human fibroblasts, keratinocytes, and human microvascular endothelial cells. After 14 days at the air-liquid interface, hematoxylin & eosin and immunohistological staining revealed a specific histological architecture representative of the human dermis and epidermis including a papillary-like architecture at the dermal-epidermal-junction. The formation of the skin barrier was measured non-destructively using impedance spectroscopy. Additionally, endothelial cells lined the walls of the formed vessels that could be perfused with a physiological volume flow. Due to the presence of a complex in-vivo-like vasculature, the here shown skin equivalent has the potential for skin grafting and represents a sophisticated in vitro model for dermatological research. KW - alternative to animal testing KW - skin equivalents KW - tissue engineering KW - vascularization Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-164438 VL - 33 IS - 4 ER - TY - JOUR A1 - Weigel, Tobias A1 - Malkmus, Christoph A1 - Weigel, Verena A1 - Wußmann, Maximiliane A1 - Berger, Constantin A1 - Brennecke, Julian A1 - Groeber‐Becker, Florian A1 - Hansmann, Jan T1 - Fully Synthetic 3D Fibrous Scaffolds for Stromal Tissues—Replacement of Animal‐Derived Scaffold Materials Demonstrated by Multilayered Skin JF - Advanced Materials N2 - The extracellular matrix (ECM) of soft tissues in vivo has remarkable biological and structural properties. Thereby, the ECM provides mechanical stability while it still can be rearranged via cellular remodeling during tissue maturation or healing processes. However, modern synthetic alternatives fail to provide these key features among basic properties. Synthetic matrices are usually completely degraded or are inert regarding cellular remodeling. Based on a refined electrospinning process, a method is developed to generate synthetic scaffolds with highly porous fibrous structures and enhanced fiber‐to‐fiber distances. Since this approach allows for cell migration, matrix remodeling, and ECM synthesis, the scaffold provides an ideal platform for the generation of soft tissue equivalents. Using this matrix, an electrospun‐based multilayered skin equivalent composed of a stratified epidermis, a dermal compartment, and a subcutis is able to be generated without the use of animal matrix components. The extension of classical dense electrospun scaffolds with high porosities and motile fibers generates a fully synthetic and defined alternative to collagen‐gel‐based tissue models and is a promising system for the construction of tissue equivalents as in vitro models or in vivo implants. KW - 3D scaffolds KW - electrospinning KW - highly porous materials KW - multilayered skin KW - stromal tissues Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-276403 VL - 34 IS - 10 ER - TY - JOUR A1 - Gensler, Marius A1 - Leikeim, Anna A1 - Möllmann, Marc A1 - Komma, Miriam A1 - Heid, Susanne A1 - Müller, Claudia A1 - Boccaccini, Aldo R. A1 - Salehi, Sahar A1 - Groeber-Becker, Florian A1 - Hansmann, Jan T1 - 3D printing of bioreactors in tissue engineering: A generalised approach JF - PLoS One N2 - 3D printing is a rapidly evolving field for biological (bioprinting) and non-biological applications. Due to a high degree of freedom for geometrical parameters in 3D printing, prototype printing of bioreactors is a promising approach in the field of Tissue Engineering. The variety of printers, materials, printing parameters and device settings is difficult to overview both for beginners as well as for most professionals. In order to address this problem, we designed a guidance including test bodies to elucidate the real printing performance for a given printer system. Therefore, performance parameters such as accuracy or mechanical stability of the test bodies are systematically analysed. Moreover, post processing steps such as sterilisation or cleaning are considered in the test procedure. The guidance presented here is also applicable to optimise the printer settings for a given printer device. As proof of concept, we compared fused filament fabrication, stereolithography and selective laser sintering as the three most used printing methods. We determined fused filament fabrication printing as the most economical solution, while stereolithography is most accurate and features the highest surface quality. Finally, we tested the applicability of our guidance by identifying a printer solution to manufacture a complex bioreactor for a perfused tissue construct. Due to its design, the manufacture via subtractive mechanical methods would be 21-fold more expensive than additive manufacturing and therefore, would result in three times the number of parts to be assembled subsequently. Using this bioreactor we showed a successful 14-day-culture of a biofabricated collagen-based tissue construct containing human dermal fibroblasts as the stromal part and a perfusable central channel with human microvascular endothelial cells. Our study indicates how the full potential of biofabrication can be exploited, as most printed tissues exhibit individual shapes and require storage under physiological conditions, after the bioprinting process. KW - stem cells KW - technology Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-231368 VL - 15 IS - 11 ER -