Coordinated Motion of Epithelial Layers on Curved Surfaces

Coordinated cellular movements are key processes in tissue morphogenesis. Using a cell-based modeling approach we study the dynamics of epithelial layers lining surfaces with constant and varying curvature. We demonstrate that extrinsic curvature effects can explain the alignment of cell elongation with the principal directions of curvature. Together with specific self-propulsion mechanisms and cell-cell interactions this effect gets enhanced and can explain observed large-scale, persistent, and circumferential rotation on cylindrical surfaces. On toroidal surfaces the resulting curvature coupling is an interplay of intrinsic and extrinsic curvature effects. These findings unveil the role of curvature and postulate its importance for tissue morphogenesis.

[Further development of regional early care-Many roads lead to Rome : Developmental stages of four established rheumatological early care concepts in different regions of Germany]

In order to shorten the prognostically relevant waiting time until diagnosis and initiation of appropriate treatment in inflammatory rheumatic diseases, rheumatological centers in many regions across Germany have established and continuously developed specific early care concepts. Evaluated models from Altötting·Burghausen, Berlin Buch, Düsseldorf and Heidelberg and their developmental stages as a response to internal and external challenges are presented in this overview. The transparent publication of the developmental steps and the exchange of experiences aim at promoting new early care concepts in other regions and continuing the joint dialogue for improvement of the early detection and quality of care of inflammatory rheumatic diseases in Germany.

Impact of contact inhibition on collective cell migration and proliferation

Contact inhibition limits migration and proliferation of cells in cell colonies. We consider a multiphase field model to investigate the growth dynamics of a cell colony, composed of proliferating cells. The model takes into account the mechanism of contact inhibition of proliferation by local mechanical interactions. We compare nonmigrating and migrating cells, in order to provide a quantitative characterization of the dynamics and analyze the velocity of the colony boundary for both cases. Additionally, we measure single cell velocities, number of neighbor distributions, as well as the influence of stress and age on positions of the cells and with respect to each other.

Multiphase field models for collective cell migration

Confluent cell monolayers and epithelia tissues show remarkable patterns and correlations in structural arrangements and actively driven collective flows. We simulate these properties using multiphase field models. The models are based on cell deformations and cell-cell interactions and we investigate the influence of microscopic details to incorporate active forces on emerging phenomena. We compare four different approaches, one in which the activity is determined by a random orientation, one where the activity is related to the deformation of the cells, and two models with subcellular details to resolve the mechanochemical interactions underlying cell migration. The models are compared with respect to generic features, such as coordination number distribution, cell shape variability, emerging nematic properties, as well as vorticity correlations and flow patterns in large confluent monolayers and confinements. All results are compared with experimental data for a large variety of cell cultures. The appearing qualitative differences of the models show the importance of microscopic details and provide a route towards predictive simulations of patterns and correlations in cell colonies.

Metabolic activation and toxicological evaluation of polychlorinated biphenyls in Drosophila melanogaster

Degradation of polychlorinated biphenyls (PCBs) is initiated by cytochrome P450 (CYP) enzymes and includes PCB oxidation to OH-metabolites, which often display a higher toxicity than their parental compounds. In search of an animal model reflecting PCB metabolism and toxicity, we tested Drosophila melanogaster, a well-known model system for genetics and human disease. Feeding Drosophila with lower chlorinated (LC) PCB congeners 28, 52 or 101 resulted in the detection of a human-like pattern of respective OH-metabolites in fly lysates. Feeding flies high PCB 28 concentrations caused lethality. Thus we silenced selected CYPs via RNA interference and analyzed the effect on PCB 28-derived metabolite formation by assaying 3-OH-2',4,4'-trichlorobiphenyl (3-OHCB 28) and 3'-OH-4',4,6'-trichlorobiphenyl (3'-OHCB 28) in fly lysates. We identified several drosophila CYPs (dCYPs) whose knockdown reduced PCB 28-derived OH-metabolites and suppressed PCB 28 induced lethality including dCYP1A2. Following in vitro analysis using a liver-like CYP-cocktail, containing human orthologues of dCYP1A2, we confirm human CYP1A2 as a PCB 28 metabolizing enzyme. PCB 28-induced mortality in flies was accompanied by locomotor impairment, a common phenotype of neurodegenerative disorders. Along this line, we show PCB 28-initiated caspase activation in differentiated fly neurons. This suggested the loss of neurons through apoptosis. Our findings in flies are congruent with observation in human exposed to high PCB levels. In plasma samples of PCB exposed humans, levels of the neurofilament light chain increase after LC-PCB exposure, indicating neuronal damage. In summary our findings demonstrate parallels between Drosophila and the human systems with respect to CYP mediated metabolism and PCB mediated neurotoxicity.

NanoPASS: an easy-to-use user interface for nanoparticle dosimetry with the 3DSDD model

Nanoparticles exhibit a specific diffusion and sedimentation behavior under cell culture conditions as used in nantoxicological in vitro testing. How a particular particle suspension behaves depends on the particular physicochemical characteristics of the particles and the cell culture system. Only a fraction of the nanoparticles applied to a cell culture will thus reach the cells within a given time frame. Therefore, dosimetric calculations are essential not only to determine the exact fraction of nanoparticles that has come into contact with the cells, but also to ensure experimental comparability and correct interpretation of results, respectively. Yet, the use of published dosimetry models is limited. Not the least because the correct application of these in silico tools usually requires bioinformatics knowledge, which often is perceived a hurdle. Moreover, not all models are freely available and accessible. In order to overcome this obstacle, we have now developed an easy-to-use interface for our recently published 3DSDD dosimetry model, called NanoPASS (NanoParticle Administration Sedimentation Simulator). The interface is freely available to all researchers. It will facilitate the use of in silico dosimetry in nanotoxicology and thus improve interpretation and comparability of in vitro results in the field.

Biomimetic reconstruction of the hematopoietic stem cell niche for in vitro amplification of human hematopoietic stem cells

Hematopoietic stem cell transplantation is successfully applied since the late 1950s; however, its efficacy still needs to be increased. A promising strategy is to transplant high numbers of pluripotent hematopoietic stem cells (HSCs). Therefore, an improved ex vivo culture system that supports proliferation and maintains HSC pluripotency would override possible limitations in cell numbers gained from donors. To model the natural HSC niche in vitro, we optimized the HSC medium composition with a panel of cytokines and valproic acid and used an artificial 3D bone marrow-like scaffold made of polydimethylsiloxane (PDMS). This 3D scaffold offered a suitable platform to amplify human HSCs in vitro and, simultaneously, to support their viability, multipotency and ability for self-renewal. Silicon oxide-covering of PDMS structures further improved amplification of CD34+ cells, although the conservation of naïve HSCs was better on non-covered 3D PDMS. Finally, we found that HSC cultivated on non-covered 3D PDMS generated most pluripotent colonies within colony forming unit assays. In conclusion, by combining biological and biotechnological approaches, we optimized in vitro HSCs culture conditions, resulting in improved amplification, multipotency maintenance and vitality of HSCs.

Analysis of microscopic bone properties in an osteoporotic sheep model: a combined biomechanics, FE and ToF-SIMS study

The present study deals with the characterization of bone quality in a sheep model of postmenopausal osteoporosis. Sheep were sham operated ( n = 7), ovariectomized ( n = 6), ovariectomized and treated with deficient diet ( n = 8) or ovariectomized, treated with deficient diet and glucocorticoid injections ( n = 7). The focus of the study is on the microscopic properties at tissue level. Microscopic mechanical properties of osteoporotic bone were evaluated by a combination of biomechanical testing and mathematical modelling. Sample stiffness and strength were determined by compression tests and finite-element analysis of stress states was conducted. From this, an averaged microscopic Young's modulus at tissue level was determined. Trabecular structure as well as mineral and collagen distribution in samples of sheep vertebrae were analysed by micro-computed tomography and time-of-flight secondary ion mass spectrometry. In the osteoporotic sheep model, a disturbed fibril structure in the triple treated group was observed, but bone loss only occurred in form of reduced trabecular number and thickness and cortical decline, while quality of the residual bone was preserved. The preserved bone tissue properties in the osteoporotic sheep model allowed for an estimation of bone strength which behaves similar to the human case.

[Early recognition and screening consultation: a necessary way to improve early detection and treatment in rheumatology? : Overview of the early recognition and screening consultation models for rheumatic and musculoskeletal diseases in Germany]

In order to reduce the prognostically relevant time interval between the initial manifestation of a rheumatic and musculoskeletal disease and diagnosis as well as the consecutive initiation of an appropriate treatment, several rheumatological centers in Germany have improved the access to initial rheumatologic evaluation by establishing early recognition/screening clinics at their respective sites. Corresponding models located at Altoetting·Burghausen, Bad Pyrmont, Berlin Buch, Duesseldorf, Heidelberg, Herne, Mannheim as well as supraregional/multicenter initiatives Rheuma Rapid, RhePort and Rheuma-VOR are presented in this overview along with the respective characteristics, potential advantages and disadvantages, but also first evaluation results of several models. The aim of this publication is to promote early detection of rheumatic and musculoskeletal diseases as one of the most important challenges in current rheumatology by encouraging further rheumatologic centers and practices to launch their own early recognition/screening consultation model on the basis of aspects presented herein.

Testicular organoids to study cell-cell interactions in the mammalian testis

BACKGROUND

Over the last ten years, three-dimensional organoid culture has garnered renewed interest, as organoids generated from primary cells or stem cells with cell associations and functions similar to organs in vivo can be a powerful tool to study tissue-specific cell-cell interactions in vitro. Very recently, a few interesting approaches have been put forth for generating testicular organoids for studying the germ cell niche microenvironment.

AIM

To review different model systems that have been employed to study germ cell biology and testicular cell-cell interactions and discuss how the organoid approach can address some of the shortcomings of those systems.

RESULTS AND CONCLUSION

Testicular organoids that bear architectural and functional similarities to their in vivo counterparts are a powerful model system to study cell-cell interactions in the germ cell niche. Organoids enable studying samples in humans and other large animals where in vivo experiments are not possible, allow modeling of testicular disease and malignancies and may provide a platform to design more precise therapeutic interventions.

Controlling Grain Boundaries by Magnetic Fields

The ability to use external magnetic fields to influence the microstructure in polycrystalline materials has potential applications in microstructural engineering. To explore this potential and to understand the complex interactions between electromagnetic fields and solid-state matter transport we consider a phase-field-crystal model. Together with efficient and scalable numerical algorithms this allows the examination of the role that external magnetic fields play on the evolution of defect structures and grain boundaries, on diffusive timescales. Examples for planar and circular grain boundaries explain the essential atomistic processes and large scale simulations in 2D are used to obtain statistical data on grain growth under the influence of external fields.

In vitro nanoparticle dosimetry for adherent growing cell monolayers covering bottom and lateral walls

Background

Even though a continuously high number of in vitro studies on nanoparticles are being published, the issue of correct dose matter is often not sufficiently taken into account. Due to their size, the diffusion of nanoparticles is slower, as compared to soluble chemicals, and they sediment slowly. Therefore, the administered dose of particles in in vitro experiments is not necessarily the same (effective) dose that comes into contact with the cellular system. This can lead to misinterpretations of experimental toxic effects and disturbs the meaningfulness of in vitro studies. In silico calculations of the effective nanoparticle dose can help circumventing this problem.

Results

This study addresses more complex in vitro models like the human intestinal cell line Caco-2 or the human liver cell line HepaRG, which need to be differentiated over a few weeks to reach their full complexity. During the differentiation time the cells grow up the wall of the cell culture dishes and therefore a three-dimensional-based in silico model of the nanoparticle dose was developed to calculate the administered dose received by different cell populations at the bottom and the walls of the culture dish. Moreover, the model can perform calculations based on the hydrodynamic diameter which is measured by light scattering methods, or based on the diffusion coefficient measured by nanoparticle tracking analysis (NTA). This 3DSDD (3D-sedimentation-diffusion-dosimetry) model was experimentally verified against existing dosimetry models and was applied to differentiated Caco-2 cells incubated with silver nanoparticles.

Conclusions

The 3DSDD accounts for the 3D distribution of cells in in vitro cell culture dishes and is therefore suitable for differentiated cells. To encourage the use of dosimetry calculating software, our model can be downloaded from the supporting information.

Electronic supplementary material

The online version of this article (10.1186/s12989-018-0278-9) contains supplementary material, which is available to authorized users.

[Improved early diagnostics of rheumatic diseases : Monocentric experiences with an open rheumatological specialist consultation]

AIM OF THE PROJECT

To establish an open rheumatological outpatient consultation service for early diagnosis of inflammatory rheumatic diseases and initiation of further diagnostics and treatment.

METHODS

In 2015 an open consultation service was initiated for patients with signs of an early rheumatic disease after referral by primary care physicians. Patients could attend once a week without the need for a prior appointment if they fulfilled at least one of the following criteria: positive rheumatoid factor, increased CRP, anti-CCP antibody or antinuclear antibody, joint pain or back pain for over 3 months, swollen joints, fever of unknown origin or acute muscle pain with or without headache of unknown origin. This article presents the results of the retrospective descriptive data analysis of the first 2 years of this project.

RESULTS

A total of 1262 patients were treated with an average of approximately 20 patients per consultation. In nearly half of the patients an inflammatory rheumatological disease could be diagnosed and immediate diagnostic and treatment measures could be initiated. The diagnostic delay for patients with rheumatoid arthritis was 12 weeks, for patients with polymyalgia rheumatica 11 weeks and for patients with psoriatic arthritis or axial spondylarthritis 18 and 44 weeks, respectively. The time expenditure was a total of 4-5 h per week for an experienced rheumatologist and a specialized rheumatology nurse.

CONCLUSION

Through this open rheumatological outpatient consultation a low threshold opportunity for the early diagnosis of rheumatologic diseases could be established. The diagnostic delay for many rheumatological diseases could be considerably shortened. Cooperation with rheumatologists in private practice guaranteed the subsequent specialized rheumatological care of the identified patients in the early stages of their illness.

Pregnancy in Upshaw-Schulman syndrome

The Upshaw Schulman syndrome (MIM #274150) is a hereditary deficiency of the von Willebrand factor cleaving protease (ADAMTS13) due to homozygous or compound heterozygous mutations in the ADAMTS13 gene. Patients are prone to bouts of thrombotic thrombocytopenic purpura. However, disease manifestation needs a second trigger event. Pregnancy is a known risk factor for TTP. Patients with USS may manifest during pregnancy and the postpartum period or relapse with a TTP bout. Before plasma therapy mortality for both the mother and the fetus was high, but even nowadays when plasma is delivered, therapy is challenging, still bearing a high risk for miscarriage or long term sequelae for the mother.

In this report on pregnancies in three mothers with USS, plasma therapy was increased in frequency and amount given with regard to platelet count or ADAMTS13 activity, thus leading to a successful outcome.

Electrically Tunable Dye Emission via Microcavity Integrated PDMS Gel Actuator

Electrically tunable microcavities are essential elements for tunable laser sources indispensable for modern telecommunication and spectroscopy. However, most device concepts suffer from extensive lithography or etching for membrane processing. Here, we present an electrically and continuously tunable, multi-half-wavelength microcavity with a quality factor > 1000 as an easy-to-fabricate platform with potential use for vertical-cavity surface-emitting lasers. The microcavity has a Fabry-Pérot structure consisting of ultrasoft PDMS gel with a thickness of 14-15 μm and capped by a distributed Bragg reflector on the bottom end and a silver layer serving as top mirror and electrode. Additionally, we have embedded a pyrromethene dye into the PDMS matrix to prove efficient gain medium integration. By means of an integrated dielectric elastomer actuator, the microcavity thickness is varied 1.3 μm (9%) with a driving voltage of 70 V. The subsequent silver mirror deflection achieves a reversible 40 nm tuning of the cavity resonance wavelength. The tuning range is limited by the lateral bending of the electrodes for increasing voltages. This characteristic bending is confirmed by simulations with finite elements method. The dynamic behavior of the microcavity is characterized by capacitance measurements and modeled by viscoelastic theory. Our research provides in-depth examinations of electrically tunable, PDMS gel-based microcavities with the future goal of building simple, miniaturized, and cost-efficient laser sources with high tuning range.

Suspended Liquid Subtractive Lithography: One-step generation of 3D channel geometries in viscous curable polymer matrices

The miniaturization of synthesis, analysis and screening experiments is an important step towards more environmentally friendly chemistry, statistically significant biology and fast and cost-effective medicinal assays. The facile generation of arbitrary 3D channel structures in polymers is pivotal to these techniques. Here we present a method for printing microchannels directly into viscous curable polymer matrices by injecting a surfactant into the uncured material via a steel capillary attached to a 3D printer. We demonstrate this technique using polydimethylsiloxane (PDMS) one of the most widely used polymers for the fabrication of, e. g. microfluidic chips. We show that this technique which we term Suspended Liquid Subtractive Lithography (SLSL) is well suited for printing actuators, T-junctions and complex three dimensional structures. The formation of truly arbitrary channels in 3D could revolutionize the fabrication of miniaturized chips and will find broad application in biology, chemistry and medicine.