Introduction To Advancedy Tem On Chip Te T De Ign And Optimization Pdf
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Abstract: The paper considers the potential of freeform optics for Li -Fi techno logy and presents design appro aches f or. Simulation results are then presented for m odels validation. The pr oce edi ng dig ita liz ati on of our env iron ment lead s. In ter-c han nel inte rfe renc e is an. Th e so -call ed.
Handbook of Advanced Lighting Technology
Current available in vitro placental transfer models are often inappropriate for translocation studies of macromolecules or NPs and do not consider barrier function of placental endothelial cells EC. Translocation studies with four model substances and two polystyrene PS NPs across the individual and co-culture layers revealed that for most of these compounds, the trophoblast and the EC layer both demonstrate similar, but not additive, retention capacity. Only the paracellular marker Na-F was substantially more retained by the BeWo layer.
Furthermore, simple shaking, which is often applied to mimic placental perfusion, did not alter translocation kinetics compared to static exposure. In conclusion, we developed a novel placental co-culture model, which provides predictive values for translocation of a broad variety of molecules and NPs and enables valuable mechanistic investigations on cell type-specific placental barrier function.
The placenta acts as an interface between the fetus and the expecting mother. This transient organ enables and supports pregnancy by e. However, it has been recognized that various drugs, environmental pollutants and even certain nanoparticles NP are able to cross the placental barrier 1 , 2 , 3 , 4 , 5 , 6.
Nevertheless, the pregnant woman is still considered a drug orphan, and medication development, evaluation and safety trials in pregnancy are markedly under-represented 8. Despite the fact that comprehensive drug safety and efficacy data are often lacking, the use of drugs in pregnancy is widespread 9 , Drugs that are used to treat acute or chronic diseases of the expecting mother could jeopardize pregnancy and the health of the unborn child 11 , 12 , 13 , In contrast, prenatal drug treatment of fetal diseases or placental complications could elicit adverse side effects in the mother 15 , Thus safe and highly specific therapeutic strategies to treat the mother, the fetus or placental conditions without off-target effects are of great interest.
A highly promising strategy to enhance targeted therapy and avoid undesired side effects is the use of NPs as drug carriers 17 , 18 , 19 , However, the impact of NP properties and surface modifications on placental uptake, accumulation and translocation as well as the underlying transport mechanisms are not yet clearly understood 21 , 22 , Animals, mainly rodents, can provide information on placental transfer of substances or NPs in a living organism as well as on their potential adverse effects on the offspring.
However, an extrapolation to the human situation is highly questionable since the placenta is the most species-specific organ 24 , Therefore, predictive in vitro and ex vivo placenta models using human cells or tissue are necessary to avoid species-specific differences.
In contrast, widely used in vitro translocation models i. However, this model does not fully resemble the physiological structure of the placental barrier. In the first trimester, the placental barrier is composed of four different layers, namely the syncytiotrophoblast STB , the cytotrophoblast CTB , the fetal stroma and the fetal endothelial cells EC of the capillaries Fig.
During pregnancy the placental barrier becomes thinner as the STB layer thins, fetal capillaries move to the periphery of the villi and the phenotype of the CTBs transforms from cuboidal to flat. Scheme of the human placental barrier at term and the co-culture translocation model. Huang et al. However, access to term placentae is restricted and isolation of primary trophoblasts is laborious and expensive. Other research groups developed first dynamic co-culture placenta models exploiting macro- or microfluidic approaches 33 , 34 , In all models, co-cultures of trophoblastic and endothelial cells were cultivated on either a denuded amniotic membrane 33 , a microporous PDMS poly -dimethylsiloxane membrane 34 or a vitrified collagen membrane For instance, FITC-dextran 4.
Moreover, PDMS-based microfluidic devices are known to absorb small hydrophilic molecules and so impede reliable drug transfer studies 37 , 38 , To conclude, the different improvement strategies co-cultures, primary cells, dynamic exposure are very promising but further model optimization is urgently needed to render them suitable for translocation studies not only of small molecules but also of macromolecules and NPs.
In this study a new in vitro co-culture model simulating the human placental barrier was developed. Given that not only the syncytiotrophoblast but also the microvasculature endothelium strongly contributes to the total placental permeability 40 , 41 , 42 , a co-culture barrier with trophoblast cells on the apical side and endothelial cells on the basolateral side of the microporous membrane was established Fig.
Among the different trophoblast cell lines, the BeWo b30 clone best resembles human villous trophoblasts, when considering structure and function 43 , 44 , 45 , In addition, the relative transfer rates of small substances determined in monolayer BeWo models correlate well with transfer indices from ex vivo placenta perfusions 47 , In contrast to previous co-culture models that used macrovascular endothelial cells e.
HUVECs 33 , 34 , 35 , we exploited a microvascular human placental venous endothelial cell line HPEC-A2 since major phenotypic and physiologic differences exist between micro-and macrovascular endothelial cells 49 , 50 , To our knowledge, this is the first placental co-culture model that incorporates the two key cellular barriers of the human placenta as well as the currently most suitable porous support to assess translocation of a large variety of low to high molecular weight compounds and NPs.
Translocation rates were assessed under static and shaken conditions to determine the need of a simple dynamic experimental set up, when investigating placental translocation in vitro , since horizontal shaking is often performed to mimic in vivo exposure.
Here, a microporous membrane system was used to develop a co-culture model representing the human placental barrier at the end of pregnancy Fig. BeWo cells mimicking the trophoblast layer were grown on the apical side of the membrane and were co-cultured with microvascular endothelial cells HPEC-A2 on the basolateral side. To identify a suitable medium for optimal growth and viability of the co-cultures, cells were cultivated in the recommended media for each cell type TM or EM as well as in a mixture of both media for up to 5 days see Supplementary Fig.
Since BeWo cells have been cultivated in a variety of different media while microvascular ECs were exclusively grown in EM, we have chosen EM as the co-culture medium.
To establish a confluent monolayer BeWo cells in EM, different cell seeding numbers of 1. Cell numbers were chosen close to the recommended seeding number of 1. A lower or higher cell number 1. In contrast to BeWo cells, HPECs are contact-inhibited and formed a confluent monolayer after 3 d when using an initial cell number of 1. Establishment of the co-culture. TEER values of co-cultures highly increased over time and reached In addition, TEM and LM images of 3 d co-cultures showed that HPEC cells formed a confluent monolayer, while the BeWo cell layer was mostly present as a monolayer containing small areas where bilayer formation was evident Fig.
TEM micrographs further revealed the formation of tight cell-cell contacts in both cell types after 3 d of cultivation and the polarization of the BeWo layer due to microvilli formation Fig.
Morphological investigation of the co-culture after 3 d of cultivation. Since the co-culture model showed placenta specific structural characteristics and formed a sufficiently tight barrier, translocation studies were conducted with different model substances and PS NPs. Translocation studies across mono- and co-cultures were performed under static and shaken conditions. Investigation of size-dependent paracellular transport was performed using two hydrophilic substances Na-F 0.
Antipyrine, widely used as reference compound in placenta perfusion experiments, and indomethacin were used as transcellular markers, since both compounds are known to rapidly cross the human placental barrier. To exclude that collagen-coating blocked the insert pores, transfer of Na-F, FITC-dextran and PS NPs was investigated across empty control inserts in the presence or absence of a collagen-coating see Supplementary Fig.
No considerable difference between collagen-coated and uncoated membranes was observed for all substances and particles. Na-F did easily pass the empty membrane. Only a small amount of 6. Translocation of FITC-dextran was even further diminished in the presence of a BeWo monolayer or in co-cultures median 0.
Translocation profiles of antipyrine and indomethacin across either BeWo and HPEC monolayers or the co-culture were highly similar Fig. In contrast to indomethacin, antipyrine was transported faster and in higher amounts. When PS NPs were applied, the membrane started to contribute more substantially towards the overall barrier function but transfer across control inserts was still In the presence of the single cell layers or co-cultures, both NPs were highly retained since only 2.
To assess the impact of horizontal shaking, transfer kinetics of the same substances and NPs were determined under shaken conditions. In general, similar transfer rates as in static conditions were determined for all substances and NPs see Supplementary Fig. To compare the translocation of the different substances and NPs with each other and with published data, permeability factors were calculated according to the formulas given in the materials and methods description.
Moreover, no statistical significance was found comparing the P e values obtained in static and shaken conditions. Translocation studies at the placental barrier are key to predict potential fetal exposure and teratogenic effects. A comprehensive knowledge on uptake and translocation mechanisms is indispensable for the safe design and use of drugs and NPs in industrial and medical applications.
Predictive human placenta models are a prerequisite to achieve meaningful results since the placenta is considered to be the most species-specific mammalian organ.
Although complex ex vivo placenta models exist, their applicability for mechanistic translocation studies is limited due to the restricted access to human placental tissue or high donor-to-donor variations, among others.
Consequently, there is a strong need for advanced in vitro alternatives but the most frequently used BeWo transfer model does not take into account the multilayered placental barrier structure or the highly dynamic environment of the physiological situation. First studies highlighting the importance of including endothelial cells in placental translocation models are emerging 33 , For instance, it has been shown that the endothelial cell layer seems more resistive to glucose transfer than the trophoblast layer Therefore the aim of this study was to increase the predictive value of the widely used in vitro BeWo transfer model and to make it suitable for transfer studies of large molecules and NPs.
Larger pore sizes would lead to transmigration of the cells through the membrane pores while smaller pore sizes are imposing a major barrier for the free transfer of larger compounds or NPs. After optimization of the cultivation conditions, tight cell layers were obtained already 3 days after cell seeding. In contrast, published BeWo transfer models mostly require 5—6 days to achieve confluency.
The reason for the faster BeWo monolayer formation was most likely due to a combination of a slightly increased cell seeding number and the use of a different cultivation media. Importantly, the increased seeding number did not result in multiple cell layer formation. Polarization of the trophoblast layer was verified by the presence of microvilli at the apical surface, and is an important key characteristic that determines specific asymmetric transport of e.
Na-F exclusion and TEER measurements confirmed the formation of a tight barrier suitable for translocation studies across the individual monolayers and the co-culture.
To confirm a size-dependent transport, we investigated the translocation of Na-F 0. Recently Na-F was also found to be a substrate of organic anion transporting polypeptides OATP , which are present in BeWo cells and placental tissue in vivo 57 , 58 , 59 , Our transport studies on the individual monolayers further revealed a higher translocation of both markers across the HPEC layer than the BeWo layer, suggesting that the trophoblast barrier is tighter than the endothelial barrier.
Moreover, the barrier capacity of the co-culture was equal to the one of the BeWo layer, which indicates that the BeWo cells constitute the key cell barrier layer of the placenta for paracellular transport. Antipyrine is widely used as a reference compound in ex vivo perfusions and in vitro translocation studies and exhibits a fast translocation across the placental barrier via transcellular passive diffusion 5 , 26 , 47 , 48 , 61 , 62 , 63 , 64 , 65 , 66 , Indomethacin is known to easily pass the human placenta in vitro 47 , ex vivo 68 and in vivo throughout gestation 69 , In a previous study using the BeWo monoculture transfer model, Li et al.
These values were highly similar to the permeability values measured in this study for antipyrine P 1h : Importantly, it has been shown that the relative transfer rates of small substances determined in monolayer BeWo models correlate well with transfer indices from ex vivo placenta perfusions 47 , 48 , 71 , suggesting that our model delivers results with a high predictive value.
The applicability of our co-culture model for NP translocation studies was evaluated using PS NPs since for those NPs, there is a reasonable amount of in vitro and ex vivo data available for comparison. A similar limited transport of 3.
PDF | Significant advances have been made in the development of micro-scale Advanced Drug Delivery Reviews 55 () – and review microﬂuidic concepts, microconstruction techniques, and Introduction to micro-scale phenomena on chip directly from normal, complex and heteroge-.
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The early MIPS architectures were bit only; bit versions were developed later. The MIPS architecture has several optional extensions. Computer architecture courses in universities and technical schools often study the MIPS architecture. A  : It was designed for use in personal, workstation, and server computers.
Thesis submitted to the Royal Institute of Technology in partial fulfillment namely, on-chip network architectures, NoC network performance analysis, optimization for a classical wormhole architecture. has very limited concurrent communication capability since only one de- The non-contentional latency T for trans-.
In that book, we focused on presenting guidelines and best practices to aid engineers beginning to design complex System-on-Chip devices SoCs. Now, in , facing the mid-point of that revolution, we believe that it is time to focus on winning. In this book, Winning the SoC Revolution: Experiences in Real Design , we gather the best practical experiences in how to design SoCs from the most advanced design groups, while setting the issues and techniques in the context of SoC design methodologies. We hope that by utilizing this book, you too, will win the SoC Revolution. Skip to main content Skip to table of contents.