@article{AppeltMenzelCubukovaGuentheretal.2017, author = {Appelt-Menzel, Antje and Cubukova, Alevtina and G{\"u}nther, Katharina and Edenhofer, Frank and Piontek, J{\"o}rg and Krause, Gerd and St{\"u}ber, Tanja and Walles, Heike and Neuhaus, Winfried and Metzger, Marco}, title = {Establishment of a Human Blood-Brain Barrier Co-culture Model Mimicking the Neurovascular Unit Using Induced Pluri- and Multipotent Stem Cells}, series = {Stem Cell Reports}, volume = {8}, journal = {Stem Cell Reports}, number = {4}, doi = {10.1016/j.stemcr.2017.02.021}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170982}, pages = {894-906}, year = {2017}, abstract = {In vitro models of the human blood-brain barrier (BBB) are highly desirable for drug development. This study aims to analyze a set of ten different BBB culture models based on primary cells, human induced pluripotent stem cells (hiPSCs), and multipotent fetal neural stem cells (fNSCs). We systematically investigated the impact of astrocytes, pericytes, and NSCs on hiPSC-derived BBB endothelial cell function and gene expression. The quadruple culture models, based on these four cell types, achieved BBB characteristics including transendothelial electrical resistance (TEER) up to 2,500 Ω cm\(^{2}\) and distinct upregulation of typical BBB genes. A complex in vivo-like tight junction (TJ) network was detected by freeze-fracture and transmission electron microscopy. Treatment with claudin-specific TJ modulators caused TEER decrease, confirming the relevant role of claudin subtypes for paracellular tightness. Drug permeability tests with reference substances were performed and confirmed the suitability of the models for drug transport studies.}, language = {en} } @article{BaurNietzerKunzetal.2020, author = {Baur, Florentin and Nietzer, Sarah L. and Kunz, Meik and Saal, Fabian and Jeromin, Julian and Matschos, Stephanie and Linnebacher, Michael and Walles, Heike and Dandekar, Thomas and Dandekar, Gudrun}, title = {Connecting cancer pathways to tumor engines: a stratification tool for colorectal cancer combining human in vitro tissue models with boolean in silico models}, series = {Cancers}, volume = {12}, journal = {Cancers}, number = {1}, issn = {2072-6694}, doi = {10.3390/cancers12010028}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-193798}, pages = {28}, year = {2020}, abstract = {To improve and focus preclinical testing, we combine tumor models based on a decellularized tissue matrix with bioinformatics to stratify tumors according to stage-specific mutations that are linked to central cancer pathways. We generated tissue models with BRAF-mutant colorectal cancer (CRC) cells (HROC24 and HROC87) and compared treatment responses to two-dimensional (2D) cultures and xenografts. As the BRAF inhibitor vemurafenib is—in contrast to melanoma—not effective in CRC, we combined it with the EGFR inhibitor gefitinib. In general, our 3D models showed higher chemoresistance and in contrast to 2D a more active HGFR after gefitinib and combination-therapy. In xenograft models murine HGF could not activate the human HGFR, stressing the importance of the human microenvironment. In order to stratify patient groups for targeted treatment options in CRC, an in silico topology with different stages including mutations and changes in common signaling pathways was developed. We applied the established topology for in silico simulations to predict new therapeutic options for BRAF-mutated CRC patients in advanced stages. Our in silico tool connects genome information with a deeper understanding of tumor engines in clinically relevant signaling networks which goes beyond the consideration of single drivers to improve CRC patient stratification.}, language = {en} } @article{GroeberSchoberSchmidetal.2016, author = {Groeber, Florian and Schober, Lena and Schmid, Freia F. and Traube, Andrea and Kolbus-Hernandez, Silvia and Daton, Karolina and Hoffmann, Sebastian and Petersohn, Dirk and Schaefer-Korting, Monika and Walles, Heike and Mewes, Karsten R.}, title = {Catch-up validation study of an in vitro skin irritation test method based on an open source reconstructed epidermis (phase II)}, series = {Toxicology in Vitro}, volume = {36}, journal = {Toxicology in Vitro}, doi = {10.1016/j.tiv.2016.07.008}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-187311}, pages = {254-261}, year = {2016}, abstract = {To replace the Draize skin irritation assay (OECD guideline 404) several test methods based on reconstructed human epidermis (RHE) have been developed and were adopted in the OECD test guideline 439. However, all validated test methods in the guideline are linked to RHE provided by only three companies. Thus,the availability of these test models is dependent on the commercial interest of the producer. To overcome this limitation and thus to increase the accessibility of in vitro skin irritation testing, an open source reconstructed epidermis (OS-REp) was introduced. To demonstrate the capacity of the OS-REp in regulatory risk assessment, a catch-up-validation study was performed. The participating laboratories used in-house generated OS-REp to assess the set of 20 reference substances according to the performance standards amending the OECD test guideline 439. Testing was performed under blinded conditions. The within-laboratory reproducibility of 87\% and the inter-laboratory reproducibility of 85\% prove a high reliability of irritancy testing using the OS-REp protocol. In addition, the prediction capacity was with an accuracy of 80\% comparable to previous published RHE based test protocols. Taken together the results indicate that the OS-REp test method can be used as a standalone alternative skin irritation test replacing the OECD test guideline 404.}, language = {en} } @article{StrasserSchrauthDembskietal.2017, author = {Straßer, Marion and Schrauth, Joachim H. X. and Dembski, Sofia and Haddad, Daniel and Ahrens, Bernd and Schweizer, Stefan and Christ, Bastian and Cubukova, Alevtina and Metzger, Marco and Walles, Heike and Jakob, Peter M. and Sextl, Gerhard}, title = {Calcium fluoride based multifunctional nanoparticles for multimodal imaging}, series = {Beilstein Journal of Nanotechnology}, volume = {8}, journal = {Beilstein Journal of Nanotechnology}, doi = {10.3762/bjnano.8.148}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170657}, pages = {1484-1493}, year = {2017}, abstract = {New multifunctional nanoparticles (NPs) that can be used as contrast agents (CA) in different imaging techniques, such as photoluminescence (PL) microscopy and magnetic resonance imaging (MRI), open new possibilities for medical imaging, e.g., in the fields of diagnostics or tissue characterization in regenerative medicine. The focus of this study is on the synthesis and characterization of CaF\(_{2}\):(Tb\(^{3+}\),Gd\(^{3+}\)) NPs. Fabricated in a wet-chemical procedure, the spherical NPs with a diameter of 5-10 nm show a crystalline structure. Simultaneous doping of the NPs with different lanthanide ions, leading to paramagnetism and fluorescence, makes them suitable for MR and PL imaging. Owing to the Gd\(^{3+}\) ions on the surface, the NPs reduce the MR T\(_{1}\) relaxation time constant as a function of their concentration. Thus, the NPs can be used as a MRI CA with a mean relaxivity of about r = 0.471 mL·mg\(^{-1}\)·s\(^{-1}\). Repeated MRI examinations of four different batches prove the reproducibility of the NP synthesis and determine the long-term stability of the CAs. No cytotoxicity of NP concentrations between 0.5 and 1 mg·mL\(^{-1}\) was observed after exposure to human dermal fibroblasts over 24 h. Overall this study shows, that the CaF\(_{2}\):(Tb\(^{3+}\),Gd\(^{3+}\)) NPs are suitable for medical imaging.}, language = {en} } @article{HeydarianYangSchweinlinetal.2019, author = {Heydarian, Motaharehsadat and Yang, Tao and Schweinlin, Matthias and Steinke, Maria and Walles, Heike and Rudel, Thomas and Kozjak-Pavlovic, Vera}, title = {Biomimetic human tissue model for long-term study of Neisseria gonorrhoeae infection}, series = {Frontiers in Microbiology}, volume = {10}, journal = {Frontiers in Microbiology}, number = {1740}, issn = {1664-302X}, doi = {10.3389/fmicb.2019.01740}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-197912}, year = {2019}, abstract = {Gonorrhea is the second most common sexually transmitted infection in the world and is caused by Gram-negative diplococcus Neisseria gonorrhoeae. Since N. gonorrhoeae is a human-specific pathogen, animal infection models are only of limited use. Therefore, a suitable in vitro cell culture model for studying the complete infection including adhesion, transmigration and transport to deeper tissue layers is required. In the present study, we generated three independent 3D tissue models based on porcine small intestinal submucosa (SIS) scaffold by co-culturing human dermal fibroblasts with human colorectal carcinoma, endometrial epithelial, and male uroepithelial cells. Functional analyses such as transepithelial electrical resistance (TEER) and FITC-dextran assay indicated the high barrier integrity of the created monolayer. The histological, immunohistochemical, and ultra-structural analyses showed that the 3D SIS scaffold-based models closely mimic the main characteristics of the site of gonococcal infection in human host including the epithelial monolayer, the underlying connective tissue, mucus production, tight junction, and microvilli formation. We infected the established 3D tissue models with different N. gonorrhoeae strains and derivatives presenting various phenotypes regarding adhesion and invasion. The results indicated that the disruption of tight junctions and increase in interleukin production in response to the infection is strain and cell type-dependent. In addition, the models supported bacterial survival and proved to be better suitable for studying infection over the course of several days in comparison to commonly used Transwell® models. This was primarily due to increased resilience of the SIS scaffold models to infection in terms of changes in permeability, cell destruction and bacterial transmigration. In summary, the SIS scaffold-based 3D tissue models of human mucosal tissues represent promising tools for investigating N. gonorrhoeae infections under close-to-natural conditions.}, language = {en} } @article{SchwedhelmZdziebloAppeltMenzeletal.2019, author = {Schwedhelm, Ivo and Zdzieblo, Daniela and Appelt-Menzel, Antje and Berger, Constantin and Schmitz, Tobias and Schuldt, Bernhard and Franke, Andre and M{\"u}ller, Franz-Josef and Pless, Ole and Schwarz, Thomas and Wiedemann, Philipp and Walles, Heike and Hansmann, Jan}, title = {Automated real-time monitoring of human pluripotent stem cell aggregation in stirred tank reactors}, series = {Scientific Reports}, volume = {9}, journal = {Scientific Reports}, doi = {10.1038/s41598-019-48814-w}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-202649}, pages = {12297}, year = {2019}, abstract = {The culture of human induced pluripotent stem cells (hiPSCs) at large scale becomes feasible with the aid of scalable suspension setups in continuously stirred tank reactors (CSTRs). Innovative monitoring options and emerging automated process control strategies allow for the necessary highly defined culture conditions. Next to standard process characteristics such as oxygen consumption, pH, and metabolite turnover, a reproducible and steady formation of hiPSC aggregates is vital for process scalability. In this regard, we developed a hiPSC-specific suspension culture unit consisting of a fully monitored CSTR system integrated into a custom-designed and fully automated incubator. As a step towards cost-effective hiPSC suspension culture and to pave the way for flexibility at a large scale, we constructed and utilized tailored miniature CSTRs that are largely made from three-dimensional (3D) printed polylactic acid (PLA) filament, which is a low-cost material used in fused deposition modelling. Further, the monitoring tool for hiPSC suspension cultures utilizes in situ microscopic imaging to visualize hiPSC aggregation in real-time to a statistically significant degree while omitting the need for time-intensive sampling. Suitability of our culture unit, especially concerning the developed hiPSC-specific CSTR system, was proven by demonstrating pluripotency of CSTR-cultured hiPSCs at RNA (including PluriTest) and protein level.}, language = {en} } @article{RamachandranVivaresKlieberetal.2015, author = {Ramachandran, Sarada D. and Vivar{\`e}s, Aur{\´e}lie and Klieber, Sylvie and Hewitt, Nicola J. and Muenst, Bernhard and Heinz, Stefan and Walles, Heike and Braspenning, Joris}, title = {Applicability of second-generation upcyte\(^{®}\) human hepatocytes for use in CYP inhibition and induction studies}, series = {Pharmacology Research \& Perspectives}, volume = {3}, journal = {Pharmacology Research \& Perspectives}, number = {5}, doi = {10.1002/prp2.161}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-149564}, pages = {e00161}, year = {2015}, abstract = {Human upcyte\(^{®}\) hepatocytes are proliferating hepatocytes that retain many characteristics of primary human hepatocytes. We conducted a comprehensive evaluation of the application of second-generation upcyte\(^{®}\) hepatocytes from four donors for inhibition and induction assays using a selection of reference inhibitors and inducers. CYP1A2, CYP2B6, CYP2C9, and CYP3A4 were reproducibly inhibited in a concentration-dependent manner and the calculated IC\(_{50}\) values for each compound correctly classified them as potent inhibitors. Upcyte\(^{®}\) hepatocytes were responsive to prototypical CYP1A2, CYP2B6, CYP2C9, and CYP3A4 inducers, confirming that they have functional AhR-, CAR-, and PXR-mediated CYP regulation. A panel of 11 inducers classified as potent, moderate or noninducers of CYP3A4 and CYP2B6 were tested. There was a good fit of data from upcyte\(^{®}\) hepatocytes to three different predictive models for CYP3A4 induction, namely the Relative Induction Score (RIS), AUC\(_{u}\)/F\(_{2}\), and C\(_{max,u}\)/Ind\(_{50}\). In addition, PXR (rifampicin) and CAR-selective (carbamazepine and phenytoin) inducers of CYP3A4 and CYP2B6 induction, respectively, were demonstrated. In conclusion, these data support the use of second-generation upcyte\(^{®}\) hepatocytes for CYP inhibition and induction assays. Under the culture conditions used, these cells expressed CYP activities that were equivalent to or higher than those measured in primary human hepatocyte cultures, which could be inhibited or induced by prototypical CYP inhibitors and inducers, respectively. Moreover, they can be used to predict in vivo CYP3A4 induction potential using three prediction models. Bulk availability of cells from multiple donors makes upcyte\(^{®}\) hepatocytes suitable for DDI screening, as well as more in-depth mechanistic investigations.}, language = {en} } @article{SchulteSchweinlinWestermannetal.2020, author = {Schulte, Leon N. and Schweinlin, Matthias and Westermann, Alexander J. and Janga, Harshavardhan and Santos, Sara C. and Appenzeller, Silke and Walles, Heike and Vogel, J{\"o}rg and Metzger, Marco}, title = {An Advanced Human Intestinal Coculture Model Reveals Compartmentalized Host and Pathogen Strategies during Salmonella Infection}, series = {mBio}, volume = {11, 2020}, journal = {mBio}, number = {1}, doi = {10.1128/mBio.03348-19}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-229428}, year = {2020}, abstract = {A major obstacle in infection biology is the limited ability to recapitulate human disease trajectories in traditional cell culture and animal models, which impedes the translation of basic research into clinics. Here, we introduce a three-dimensional (3D) intestinal tissue model to study human enteric infections at a level of detail that is not achieved by conventional two-dimensional monocultures. Our model comprises epithelial and endothelial layers, a primary intestinal collagen scaffold, and immune cells. Upon Salmonella infection, the model mimics human gastroenteritis, in that it restricts the pathogen to the epithelial compartment, an advantage over existing mouse models. Application of dual transcriptome sequencing to the Salmonella-infected model revealed the communication of epithelial, endothelial, monocytic, and natural killer cells among each other and with the pathogen. Our results suggest that Salmonella uses its type III secretion systems to manipulate STAT3-dependent inflammatory responses locally in the epithelium without accompanying alterations in the endothelial compartment. Our approach promises to reveal further human-specific infection strategies employed by Salmonella and other pathogens. IMPORTANCE Infection research routinely employs in vitro cell cultures or in vivo mouse models as surrogates of human hosts. Differences between murine and human immunity and the low level of complexity of traditional cell cultures, however, highlight the demand for alternative models that combine the in vivo-like properties of the human system with straightforward experimental perturbation. Here, we introduce a 3D tissue model comprising multiple cell types of the human intestinal barrier, a primary site of pathogen attack. During infection with the foodborne pathogen Salmonella enterica serovar Typhimurium, our model recapitulates human disease aspects, including pathogen restriction to the epithelial compartment, thereby deviating from the systemic infection in mice. Combination of our model with state-of-the-art genetics revealed Salmonella-mediated local manipulations of human immune responses, likely contributing to the establishment of the pathogen's infection niche. We propose the adoption of similar 3D tissue models to infection biology, to advance our understanding of molecular infection strategies employed by bacterial pathogens in their human host.}, language = {en} } @article{LotzSchmidRossietal.2016, author = {Lotz, Christian and Schmid, Freia F. and Rossi, Angela and Kurdyn, Szymon and Kampik, Daniel and De Wever, Bart and Walles, Heike and Groeber, Florian K.}, title = {Alternative Methods for the Replacement of Eye Irritation Testing}, series = {ALTEX - Alternatives to Animal Experimentation}, volume = {33}, journal = {ALTEX - Alternatives to Animal Experimentation}, number = {1}, doi = {10.14573/altex.1508241}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-164444}, pages = {55-67}, year = {2016}, abstract = {In the last decades significant regulatory attempts were made to replace, refine and reduce animal testing to assess the risk of consumer products for the human eye. As the original in vivo Draize eye test is criticized for limited predictivity, costs and ethical issues, several animal-free test methods have been developed to categorize substances according to the global harmonized system (GHS) for eye irritation. This review summarizes the progress of alternative test methods for the assessment of eye irritation. Based on the corneal anatomy and current knowledge of the mechanisms causing eye irritation, different ex vivo and in vitro methods will be presented and discussed with regard to possible limitations and status of regulatory acceptance. In addition to established in vitro models, this review will also highlight emerging, full thickness cornea models that might be suited to predict all GHS categories.}, language = {en} } @article{RosenbaumSchickWollbornetal.2016, author = {Rosenbaum, Corinna and Schick, Martin Alexander and Wollborn, Jakob and Heider, Andreas and Scholz, Claus-J{\"u}rgen and Cecil, Alexander and Niesler, Beate and Hirrlinger, Johannes and Walles, Heike and Metzger, Marco}, title = {Activation of Myenteric Glia during Acute Inflammation In Vitro and In Vivo}, series = {PLoS One}, volume = {11}, journal = {PLoS One}, number = {3}, doi = {10.1371/journal.pone.0151335}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-146544}, pages = {e0151335}, year = {2016}, abstract = {Background Enteric glial cells (EGCs) are the main constituent of the enteric nervous system and share similarities with astrocytes from the central nervous system including their reactivity to an inflammatory microenvironment. Previous studies on EGC pathophysiology have specifically focused on mucosal glia activation and its contribution to mucosal inflammatory processes observed in the gut of inflammatory bowel disease (IBD) patients. In contrast knowledge is scarce on intestinal inflammation not locally restricted to the mucosa but systemically affecting the intestine and its effect on the overall EGC network. Methods and Results In this study, we analyzed the biological effects of a systemic LPS-induced hyperinflammatory insult on overall EGCs in a rat model in vivo, mimicking the clinical situation of systemic inflammation response syndrome (SIRS). Tissues from small and large intestine were removed 4 hours after systemic LPS-injection and analyzed on transcript and protein level. Laser capture microdissection was performed to study plexus-specific gene expression alterations. Upon systemic LPS-injection in vivo we observed a rapid and dramatic activation of Glial Fibrillary Acidic Protein (GFAP)-expressing glia on mRNA level, locally restricted to the myenteric plexus. To study the specific role of the GFAP subpopulation, we established flow cytometry-purified primary glial cell cultures from GFAP promotor-driven EGFP reporter mice. After LPS stimulation, we analyzed cytokine secretion and global gene expression profiles, which were finally implemented in a bioinformatic comparative transcriptome analysis. Enriched GFAP+ glial cells cultured as gliospheres secreted increased levels of prominent inflammatory cytokines upon LPS stimulation. Additionally, a shift in myenteric glial gene expression profile was induced that predominantly affected genes associated with immune response. Conclusion and Significance Our findings identify the myenteric GFAP-expressing glial subpopulation as particularly susceptible and responsive to acute systemic inflammation of the gut wall and complement knowledge on glial involvement in mucosal inflammation of the intestine.}, language = {en} } @article{AlzheimerSvenssonKoenigetal.2020, author = {Alzheimer, Mona and Svensson, Sarah L. and K{\"o}nig, Fabian and Schweinlin, Matthias and Metzger, Marco and Walles, Heike and Sharma, Cynthia M.}, title = {A three-dimensional intestinal tissue model reveals factors and small regulatory RNAs important for colonization with Campylobacter jejuni}, series = {PLoS Pathogens}, volume = {16}, journal = {PLoS Pathogens}, number = {2}, doi = {10.1371/journal.ppat.1008304}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-229454}, year = {2020}, abstract = {The Gram-negative Epsilonproteobacterium Campylobacter jejuni is currently the most prevalent bacterial foodborne pathogen. Like for many other human pathogens, infection studies with C. jejuni mainly employ artificial animal or cell culture models that can be limited in their ability to reflect the in-vivo environment within the human host. Here, we report the development and application of a human three-dimensional (3D) infection model based on tissue engineering to study host-pathogen interactions. Our intestinal 3D tissue model is built on a decellularized extracellular matrix scaffold, which is reseeded with human Caco-2 cells. Dynamic culture conditions enable the formation of a polarized mucosal epithelial barrier reminiscent of the 3D microarchitecture of the human small intestine. Infection with C. jejuni demonstrates that the 3D tissue model can reveal isolate-dependent colonization and barrier disruption phenotypes accompanied by perturbed localization of cell-cell junctions. Pathogenesis-related phenotypes of C. jejuni mutant strains in the 3D model deviated from those obtained with 2D-monolayers, but recapitulated phenotypes previously observed in animal models. Moreover, we demonstrate the involvement of a small regulatory RNA pair, CJnc180/190, during infections and observe different phenotypes of CJnc180/190 mutant strains in 2D vs. 3D infection models. Hereby, the CJnc190 sRNA exerts its pathogenic influence, at least in part, via repression of PtmG, which is involved in flagellin modification. Our results suggest that the Caco-2 cell-based 3D tissue model is a valuable and biologically relevant tool between in-vitro and in-vivo infection models to study virulence of C. jejuni and other gastrointestinal pathogens.}, language = {en} } @article{GroeberEngelhardtLangeetal.2016, author = {Groeber, Florian and Engelhardt, Lisa and Lange, Julia and Kurdyn, Szymon and Schmid, Freia F. and R{\"u}cker, Christoph and Mielke, Stephan and Walles, Heike and Hansmann, Jan}, title = {A First Vascularized Skin Equivalent as an Alternative to Animal Experimentation}, series = {ALTEX - Alternatives to Animal Experimentation}, volume = {33}, journal = {ALTEX - Alternatives to Animal Experimentation}, number = {4}, doi = {10.14573/altex.1604041}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-164438}, pages = {415-422}, year = {2016}, abstract = {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.}, language = {en} } @article{JannaschGaetznerWeigeletal.2017, author = {Jannasch, Maren and Gaetzner, Sabine and Weigel, Tobias and Walles, Heike and Schmitz, Tobias and Hansmann, Jan}, title = {A comparative multi-parametric in vitro model identifies the power of test conditions to predict the fibrotic tendency of a biomaterial}, series = {Scientific Reports}, volume = {7}, journal = {Scientific Reports}, number = {1689}, doi = {10.1038/s41598-017-01584-9}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170908}, year = {2017}, abstract = {Despite growing effort to advance materials towards a low fibrotic progression, all implants elicit adverse tissue responses. Pre-clinical biomaterial assessment relies on animals testing, which can be complemented by in vitro tests to address the Russell and Burch's 3R aspect of reducing animal burden. However, a poor correlation between in vitro and in vivo biomaterial assessments confirms a need for suitable in vitro biomaterial tests. The aim of the study was to identify a test setting, which is predictive and might be time- and cost-efficient. We demonstrated how sensitive in vitro biomaterial assessment based on human primary macrophages depends on test conditions. Moreover, possible clinical scenarios such as lipopolysaccharide contamination, contact to autologous blood plasma, and presence of IL-4 in an immune niche influence the outcome of a biomaterial ranking. Nevertheless, by using glass, titanium, polytetrafluorethylene, silicone, and polyethylene representing a specific material-induced fibrotic response and by comparison to literature data, we were able to identify a test condition that provides a high correlation to state-of-the-art in vivo studies. Most important, biomaterial ranking obtained under native plasma test conditions showed a high predictive accuracy compared to in vivo assessments, strengthening a biomimetic three-dimensional in vitro test platform.}, language = {en} } @article{JannaschWeigelEngelhardtetal.2017, author = {Jannasch, Maren and Weigel, Tobias and Engelhardt, Lisa and Wiezoreck, Judith and Gaetzner, Sabine and Walles, Heike and Schmitz, Tobias and Hansmann, Jan}, title = {\({In}\) \({vitro}\) chemotaxis and tissue remodeling assays quantitatively characterize foreign body reaction}, series = {ALTEX - Alternatives to Animal Experimentation}, volume = {34}, journal = {ALTEX - Alternatives to Animal Experimentation}, number = {2}, doi = {10.14573/altex.1610071}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-172080}, pages = {253-266}, year = {2017}, abstract = {Surgical implantation of a biomaterial triggers foreign-body-induced fibrous encapsulation. Two major mechanisms of this complex physiological process are (I) chemotaxis of fibroblasts from surrounding tissue to the implant region, followed by (II) tissue remodeling. As an alternative to animal studies, we here propose a process-aligned \({in}\) \({vitro}\) test platform to investigate the material dependency of fibroblast chemotaxis and tissue remodeling mediated by material-resident macrophages. Embedded in a biomimetic three-dimensional collagen hydrogel, chemotaxis of fibroblasts in the direction of macrophage-material-conditioned cell culture supernatant was analyzed by live cell imaging. A combination of statistical analysis with a complementary parameterized random walk model allowed quantitative and qualitative characterization of the cellular walk process. We thereby identified an increasing macrophage-mediated chemotactic potential ranking of biomaterials from glass over polytetrafluorethylene to titanium. To address long-term effects of biomaterial-resident macrophages on fibroblasts in a three-dimensional microenvironment, we further studied tissue remodeling by applying macrophage-material-conditioned medium on fibrous \({in}\) \({vitro}\) tissue models. A high correlation of the \({in}\) \({vitro}\) tissue model to state of the art \({in}\) \({vivo}\) study data was found. Titanium exhibited a significantly lower tissue remodeling capacity compared to polytetrafluorethylene. With this approach, we identified a material dependency of both chemotaxis and tissue remodeling processes, strengthening knowledge on their specific contribution to the foreign body reaction.}, language = {en} }