A generic pump-free organ-on-a-chip platform for assessment of intestinal drug absorption

Organ-on-a-chip technology has shown great potential in disease modeling and drug evaluation. However, traditional organ-on-a-chip devices are mostly pump-dependent with low throughput, which makes it difficult to leverage their advantages. In this study, we have developed a generic, pump-free organ-on-a-chip platform consisting of a 32-unit chip and an adjustable rocker, facilitating high-throughput dynamic cell culture with straightforward operation. By utilizing the rocker to induce periodic fluid forces, we can achieve fluidic conditions similar to those obtained with traditional pump-based systems. Through constructing a gut-on-a-chip model, we observed remarkable enhancements in the expression of barrier-associated proteins and the spatial distribution of differentiated intestinal cells compared to static culture. Furthermore, RNA sequencing analysis unveiled enriched pathways associated with cell proliferation, lipid transport, and drug metabolism, indicating the ability of the platform to mimic critical physiological processes. Additionally, we tested seven drugs that represent a range of high, medium, and low in vivo permeability using this model and found a strong correlation between their Papp values and human Fa, demonstrating the capability of this model for drug absorption evaluation. Our findings highlight the potential of this pump-free organ-on-a-chip platform as a valuable tool for advancing drug development and enabling personalized medicine.

A novel 4-cell in-vitro blood-brain barrier model and its characterization by confocal microscopy and TEER measurement

The blood-brain barrier (BBB) is a protective cellular anatomical layer with a dynamic micro-environment, tightly regulating the transport of materials across it. To achieve in-vivo characteristics, an in-vitro BBB model requires the constituent cell types to be layered in an appropriate order. A cost-effective in-vitro BBB model is desired to facilitate central nervous system (CNS) drug penetration studies. Enhanced integrity of tight junctions observed during the in-vitro BBB establishment and post-experiment is essential in these models. We successfully developed an in-vitro BBB model mimicking the in-vivo cell composition and a distinct order of seeding primary human brain cells. Unlike other in-vitro BBB models, our work avoids the need for pre-coated plates for cell adhesion and provides better cell visualization during the procedure. We found that using bovine collagen-I coating, followed by bovine fibronectin coating and poly-L-lysine coating, yields better adhesion and layering of cells on the transwell membrane compared to earlier reported use of collagen and poly-L-lysine only. Our results indicated better cell visibility and imaging with the polyester transwell membrane as well as point to a higher and more stable Trans Endothelial Electrical Resistance values in this plate. In addition, we found that the addition of zinc induced higher claudin 5 expressions in neuronal cells. Dolutegravir, a drug used in the treatment of HIV, is known to appear in moderate concentrations in the CNS. Thus, dolutegravir was used to assess the functionality of the final model and cells. Using primary cells and an in-house coating strategy substantially reduces costs and provides superior imaging of cells and their tight junction protein expression. Our 4-cell-based BBB model is a suitable experimental model for the drug screening process.

Sigmoid isostiffness-lines: An in-vitro model for the assessment of aortic stenosis severity

Introduction

The aortic valve opening area (AVA), used to quantify aortic stenosis severity, depends on the transvalvular flow rate (Q). The currently accepted clinical echocardiographic method assumes a linear relation between AVA and Q. We studied whether a sigmoid model better describes this relation and determined "isostiffness-lines" across a wide flow spectrum, thus allowing building a nomogram for the non-invasive estimation of valve stiffness.

Methods

Both AVA and instantaneous Q (Qinst) were measured at 10 different mean cardiac outputs of porcine aortic valves mounted in a pulsatile flow loop. The valves' cusps were chemically stiffened to obtain three stiffness grades and the procedure was repeated for each grade. The relative stiffness was defined as the ratio between LV work at grade with the added stiffness and at native stiffness grade.AVA peak ¯ corresponding to the selectedQ peak ¯ of the highest 3 and 5 cardiac output values was predicted in K-fold cross-validation using sequentially a linear and a sigmoid model. The accuracy of each model was assessed with the Akaike information criterion (AIC).

Results

The sigmoid model predicted more accuratelyAVA peak ¯ (AIC for prediction of AVA withQ peak ¯ of the 3 highest cardiac output values: -1,743 vs. -1,048; 5 highest cardiac output values: -1,471 vs. -878) than the linear model.

Conclusion

This study suggests that the relation between AVA and Q can be better described by a sigmoid than a linear model. This construction of "isostiffness-lines" may be a useful method for the assessment of aortic stenosis in clinical echocardiography.

Transcriptome of microglia reveals a species-specific expression profile in bovines with conserved and new signature genes

Evidence is growing that microglia adopt different roles than monocyte-derived macrophages (MDM) during CNS injury. However, knowledge about their function in the pathogenesis of neuroinfections is only rudimentary. Cattle are frequently affected by neuroinfections that are either zoonotic or related to diseases in humans, and, hence, studies of bovine neuroinfections as a natural disease model may generate fundamental data on their pathogenesis potentially translatable to humans. We investigated the transcriptomic landscape and lineage markers of bovine microglia and MDM. Although bovine microglia expressed most microglial signature genes known from humans and mice, they exhibited a species-specific transcriptomic profile, including strikingly low expression of TMEM119 and enrichment of the two scavenger receptors MEGF10 and LY75. P2RY12 was amongst the most enriched genes in bovine microglia, and antibodies against P2RY12 labeled specifically resting microglia, but also reactive microglia within neuroinfection foci in-situ. On the other hand, F13A1 was amongst the most enriched genes in bovine monocytes and MDM and, additionally, the encoded protein was expressed in-situ in monocytes and MDM in the inflamed brain but not in microglia, making it a promising marker for infiltrating MDM in the brain. In culture, primary bovine microglia downregulated signature genes, expressed markers of activation, and converged their transcriptome to MDM. However, they retained several microglia signature genes that clearly distinguished them from bovine MDM, making them a promising in-vitro tool to study mechanisms of microglia-pathogen interactions.

Radiobiological Studies of Microvascular Damage through In Vitro Models: A Methodological Perspective

Ionizing radiation (IR) is used in radiotherapy as a treatment to destroy cancer. Such treatment also affects other tissues, resulting in the so-called normal tissue complications. Endothelial cells (ECs) composing the microvasculature have essential roles in the microenvironment's homeostasis (ME). Thus, detrimental effects induced by irradiation on ECs can influence both the tumor and healthy tissue. In-vitro models can be advantageous to study these phenomena. In this systematic review, we analyzed in-vitro models of ECs subjected to IR. We highlighted the critical issues involved in the production, irradiation, and analysis of such radiobiological in-vitro models to study microvascular endothelial cells damage. For each step, we analyzed common methodologies and critical points required to obtain a reliable model. We identified the generation of a 3D environment for model production and the inclusion of heterogeneous cell populations for a reliable ME recapitulation. Additionally, we highlighted how essential information on the irradiation scheme, crucial to correlate better observed in vitro effects to the clinical scenario, are often neglected in the analyzed studies, limiting the translation of achieved results.

Optimizing B-lines on lung ultrasound: an in-vitro to in-vivo pilot study with clinical implications

B-lines on lung ultrasound (US) are the hallmark of pulmonary edema. It is unknown if ultrasound machine settings or probe type matter. We created an in-vitro gelatin model. Using lung presets as baseline, five blinded investigators assessed the impact of 32 distinct settings on B-line visibility based on a Likert-Scale (LS) from 0 to10 (< 5 worse, > 5 better) separately for two probes. The experiment was then repeated in-vivo in a patient with known pulmonary edema. Based on a multivariable regression LS-ratings were similar when comparing the in-vitro versus in-vivo experiment (P = 0.16; partial R² = 0.2%) and when using the curvilinear versus linear probe (P = 0.69; partial R² = 0.02%) but significantly different across machine settings (P < 0.0001; partial R² = 34.4%). Limited by its pilot character, our study suggests that (1) certain US-machine settings heavily impact B-line visibility, with no clear difference between probes; (2) in-vitro models are a valid and practical alternative to more challenging patient-based research; (3) there is significant potential to improve B-line visibility and thus diagnostic yield in the clinical setting by using lung presets, centering the focal zone at the pleural line and increasing the distal time gain compensation, most of which are (in our experience) rarely done.

In-vitro models of human endometriosis

Endometriosis is one of the most common benign gynecological diseases in women of reproductive age worldwide. In past decades, a number of in-vitro models have been used to investigate the pathology and therapeutic methods for the treatment of endometriosis. The current review summarized the majority of currently available in-vitro models, which utilize a variety of cell or tissues types, including endometriotic cell lines, primary endometrial stromal cells, endometrial stem cells, endometrial explants, peritoneal explants and immune cells. These cells or tissues are cultured individually, co-cultured in 2D or 3D systems with various matrices or cultured in chicken chorioallantotic membranes and amniotic membranes culture systems. These models are able to represent one or more aspects of the process of endometriosis. These models are helpful and can be used to investigate the development of endometriosis and the underlying mechanisms of this disorder in detail, and help investigators select appropriate models for their experiments. Recently, the new concept of endometriosis as a fibrotic condition will lead research to investigate the differentiation of myofibroblasts and the development of fibrosis in endometriotic lesions, which will increase the development of novel models that can be used to investigate endometriotic fibrosis.

Real-time monitoring of HT29 epithelial cells as an in vitro model for assessing functional differences among intestinal microbiotas from different human population groups

Several in vitro screening tests have been used for selecting probiotic strains; however they often show low predictive value and only a limited number of strains have demonstrated functionality in vivo. The most used in vitro tests represent a very simplified version of the gut environment, especially since they do not consider the accompanying microbiota. Therefore, there is a need to develop sensitive and discriminating in vitro models including the microbiota. Here we developed an in vitro model to discriminate among microbiotas/fecal waters from different population groups. To this end samples were obtained from seven healthy adults, five IBD-patients, ten full-term and ten preterm newborns. Fecal microbiotas were purified and their impact, as well as that of the fecal waters, on HT29 cells was continuously monitored for 22 h using a real-time cell analyzer (RTCA). The composition of the purified microbiotas was assessed by 16S rRNA gene profiling and qPCR and the levels of short chain fatty acids (SCFA) determined by gas chromatography. The microbiota fractions and SCFA concentrations obtained from IBD-patients, full-term and preterm babies, showed clear differences with regard to those of the control group (healthy adults). Moreover, the purified intestinal microbiotas and fecal waters also differed from the control group in the response induced on the HT29 cells assay developed. In short, we have developed a real-time, impedance-based in vitro model for assessing the functional response induced by purified microbiotas and fecal waters upon intestinal epithelial cells. The capability of the assay for discriminating the functional responses induced, by microbiotas or fecal waters from different human groups, promises to be of help on the search for compounds/strains to restore the functionality of the microbiota-host's interaction.

[Applications of simulated gastro-intestinal model in foodborne pathogens: tolerance and pathogenesis]

We evaluated the tolerance and pathogenesis of foodborne pathogens with a simulated gastro-intestinal tract model that simulates the chemical, physical and biological effects of human digestion process under laboratory conditions. This could be used to study the tolerance, pathogenesis, gut microbiota interaction and vaccine development of foodborne pathogens, so as to contribute to control and treatment of foodborne pathogens. This review introduces the applications of simulated gastro-intestinal tract model tp evaluate foodborne pathogens, which includes in-vitro static gastro-intestinal model, in-vitro dynamic gastro-intestinal model, conventional animal model and humanized animal model. And the concepts and characteristics of all models are described in detail. Also, the shortcomings of existing models are analyzed, and improvements of artificial gastro-intestinal tract model are prospected. In conclusion, this review could provide comprehensive data for promoting the progress of studying tolerance and pathogenesis of foodborne pathogens.

Characterisation, in-vitro and in-vivo evaluation of valproic acid-loaded nanoemulsion for improved brain bioavailability

OBJECTIVE

This study was aimed to investigate the potential of formulated valproic acid-encapsulated nanoemulsion (VANE) to improve the brain bioavailability of valproic acid (VPA).

METHODS

Valproic acid-encapsulated nanoemulsions were formulated and physically characterised (osmolarity, viscosity, drug content, drug encapsulation efficiency). Further investigations were also conducted to estimate the drug release, cytotoxic profile, in-vitro blood-brain barrier (BBB) permeability, pharmacokinetic parameter and the concentration of VPA and VANE in blood and brain.

KEY FINDINGS

Physical characterisation confirmed that VANE was suitable for parenteral administration. Formulating VPA into nanoemulsion significantly reduced the cytotoxicity of VPA. In-vitro drug permeation suggested that VANEs crossed the BBB as freely as VPA. Pharmacokinetic parameters of VANE-treated rats in plasma and brain showed F3 VANE had a remarkable improvement in AUC, prolongation of half-life and reduction in clearance compared to VPA. Given the same extent of in-vitro BBB permeation of VPA and VANE, the higher bioavailability of VANE in brain was believed to have due to higher concentration of VANE in blood. The brain bioavailability of VPA was improved by prolonging the half-life of VPA by encapsulating it within the nanoemulsion-T80.

CONCLUSIONS

Nanoemulsion containing VPA has alleviated the cytotoxic effect of VPA and improved the plasma and brain bioavailability for parenteral delivery of VPA.

Novel organ-slice culturing system to simulate meniscal repair: Proof of concept using a synovium-based pool of meniscoprogenitor cells

Meniscal injuries can occur secondary to trauma or be instigated by the changes in knee-joint function that are associated with aging, osteo- and rheumatoid arthritis, disturbances in gait, and obesity. Sixty percent of persons over 50 years of age manifest signs of meniscal pathology. The surgical and arthroscopic measures that are currently implemented to treat meniscal deficiencies bring only transient relief from pain and effect but a temporary improvement in joint function. Although tissue-engineering-based approaches to meniscal repair are now being pursued, an appropriate in-vitro model has not been conceived. The aim of this study was to develop an organ-slice culturing system to simulate the repair of human meniscal lesions in vitro. The model consists of a ring of bovine meniscus enclosing a chamber that represents the defect and reproduces its sequestered physiological microenvironment. The defect, which is closed with a porous membrane, is filled with fragments of synovial tissue, as a source of meniscoprogenitor cells, and a fibrin-embedded, calcium-phosphate-entrapped depot of the meniscogenic agents BMP-2 and TGF-β1. After culturing for 2 to 6 weeks, the constructs were evaluated histochemically and histomorphometrically, as well as immunohistochemically, for the apoptotic marker caspase 3 and collagen types I and II. Under the defined conditions, the fragments of synovium underwent differentiation into meniscal tissue, which bonded with the parent meniscal wall. Both the parent and the neoformed meniscal tissue survived the duration of the culturing period without significant cell losses. The concept on which the in-vitro system is based was thus validated. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1588-1596, 2016.