Intestinal Cells-on-Chip for Permeability Studies.

Background: To accurately measure permeability of compounds in the intestine, there is a need for preclinical in vitro models that accurately represent the specificity, integrity and complexity of the human small intestinal barrier. Intestine-on-chip systems hold considerable promise as testing platforms, but several characteristics still require optimization and further development.

Methods: An established intestine-on-chip model for tissue explants was adopted for intestinal cell monolayer culture.

Thermoforming for Small Feature Replication in Melt Electrowritten Membranes to Model Kidney Proximal Tubule.

A novel approach merging melt electrowriting (MEW) with matched die thermoforming to achieve scaffolds with micron-sized curvatures (200 - 800 µm versus 1000 µm of mandrel printing) for in vitro modeling of the kidney proximal tubule (PT) is proposed. Recent advances in this field emphasize the relevance of accurately replicating the intricate tissue microenvironment, particularly the curvature of the nephrons' tubular segments. While MEW offers promising capabilities for fabricating highly and porous precise 3D structures mimicking the PT, challenges persist in approximating the diameter of tubular scaffolds to match the actual PT.

Proceedings of a membrane update symposium: advancements, scientific insights, and future trends for dialysis membranes for enhanced clinical outcomes in end stage kidney disease patients.

Purpose Of Symposium: From September 6 - 8 2022, the Life/2022 Membrane Symposium was held in Frankfurt, Germany, and transmitted live to a worldwide internet audience. The event was part of the Life/Nephrology Campus initiative, a continuous educational platform for the nephrology community to expand knowledge and share expertise on contemporary topics in chronic kidney disease. We describe recent questions and advances in the field, and we underline challenges in the care of dialysis patients and opportunities for integration of new findings into clinical practice to improve patient outcomes in end stage kidney disease patients.

Dietary protein intake and the tubular handling of indoxyl sulfate.

Background And Hypothesis: Chronic kidney disease (CKD) patients are advised to limit their protein intake. A high protein diet is known to induce glomerular hyperfiltration, as well as hypertrophy of the remnant kidney, and glomerulosclerosis. Whether the diet causes changes in kidney tubule transport via gut microbiome metabolites is still unknown.

KCNJ16-depleted kidney organoids recapitulate tubulopathy and lipid recovery upon statins treatment.

Background: The KCNJ16 gene has been associated with a novel kidney tubulopathy phenotype, viz. disturbed acid-base homeostasis, hypokalemia and altered renal salt transport. KCNJ16 encodes for Kir5.

Vascular units as advanced living materials for bottom-up engineering of perfusable 3D microvascular networks.

The timely establishment of functional neo-vasculature is pivotal for successful tissue development and regeneration, remaining a central challenge in tissue engineering. In this study, we present a novel (micro)vascularization strategy that explores the use of specialized "vascular units" (VUs) as building blocks to initiate blood vessel formation and create perfusable, stroma-embedded 3D microvascular networks from the bottom-up. We demonstrate that VUs composed of endothelial progenitor cells and organ-specific fibroblasts exhibit high angiogenic potential when embedded in fibrin hydrogels.

Cholangiocyte organoids to study drug-induced injury.

Background: Drug induced bile duct injury is a frequently observed clinical problem leading to a wide range of pathological features. During the past decades, several agents have been identified with various postulated mechanisms of bile duct damage, however, mostly still poorly understood.

Methods: Here, we investigated the mechanisms of chlorpromazine (CPZ) induced bile duct injury using advanced in vitro cholangiocyte cultures.

Development of an adverse outcome pathway network for nephrotoxicity.

Adverse outcome pathways (AOPs) were introduced in modern toxicology to provide evidence-based representations of the events and processes involved in the progression of toxicological effects across varying levels of the biological organisation to better facilitate the safety assessment of chemicals. AOPs offer an opportunity to address knowledge gaps and help to identify novel therapeutic targets. They also aid in the selection and development of existing and new in vitro and in silico test methods for hazard identification and risk assessment of chemical compounds.

Mesenchymal stromal cells secretome restores bioenergetic and redox homeostasis in human proximal tubule cells after ischemic injury.

Background: Ischemia/reperfusion injury is the leading cause of acute kidney injury (AKI). The current standard of care focuses on supporting kidney function, stating the need for more efficient and targeted therapies to enhance repair. Mesenchymal stromal cells (MSCs) and their secretome, either as conditioned medium (CM) or extracellular vesicles (EVs), have emerged as promising options for regenerative therapy; however, their full potential in treating AKI remains unknown.

Semisynthetic polymyxins with potent antibacterial activity and reduced kidney cell toxicity.

The growing incidence of infections caused by multi-drug resistant Gram-negative bacteria has led to an increased use of last-resort antibiotics such as the polymyxins. Polymyxin therapy is limited by toxicity concerns, most notably nephrotoxicity. Recently we reported the development of a novel class of semisynthetic polymyxins with reduced toxicity wherein the N-terminal lipid and diaminobutyric acid residue are replaced by a cysteine-linked lipid featuring a reductively labile disulfide bond.

Protein-Bound Uremic Toxins in Senescence and Kidney Fibrosis.

Chronic kidney disease (CKD) is a progressive condition of kidney dysfunction due to diverse causes of injury. In healthy kidneys, protein-bound uremic toxins (PBUTs) are cleared from the systemic circulation by proximal tubule cells through the concerted action of plasma membrane transporters that facilitate their urinary excretion, but the endogenous metabolites are hardly removed with kidney dysfunction and may contribute to CKD progression. Accumulating evidence suggests that senescence of kidney tubule cells influences kidney fibrosis, the common endpoint for CKD with an excessive accumulation of extracellular matrix (ECM).

Animal Models for Studying Protein-Bound Uremic Toxin Removal-A Systematic Review.

Protein-bound uremic toxins (PBUTs) are associated with the progression of chronic kidney disease (CKD) and its associated morbidity and mortality. The conventional dialysis techniques are unable to efficiently remove PBUTs due to their plasma protein binding. Therefore, novel approaches are being developed, but these require validation in animals before clinical trials can begin.

Food allergen sensitization on a chip: the gut-immune-skin axis.

The global population is growing, rapidly increasing the demand for sustainable, novel, and safe food proteins with minimal risks of food allergy. In vitro testing of allergy-sensitizing capacity is predominantly based on 2D assays. However, these lack the 3D environment and crosstalk between the gut, skin, and immune cells essential for allergy prediction.

Bioengineered Kidney Tubules Efficiently Clear Uremic Toxins in Experimental Dialysis Conditions.

Patients with end-stage kidney disease (ESKD) suffer from high levels of protein-bound uremic toxins (PBUTs) that contribute to various comorbidities. Conventional dialysis methods are ineffective in removing these PBUTs. A potential solution could be offered by a bioartificial kidney (BAK) composed of porous membranes covered by proximal tubule epithelial cells (PTECs) that actively secrete PBUTs.

The application of organ-on-chip models for the prediction of human pharmacokinetic profiles during drug development.

Organ-on-chip (OoC) technology has led to in vitro models with many new possibilities compared to conventional in vitro and in vivo models. In this review, the potential of OoC models to improve the prediction of human oral bioavailability and intrinsic clearance is discussed, with a focus on the functionality of the models and the application in current drug development practice. Multi-OoC models demonstrating the application for pharmacokinetic (PK) studies are summarized and existing challenges are identified.

Portable, wearable and implantable artificial kidney systems: needs, opportunities and challenges.

Haemodialysis is life sustaining but expensive, provides limited removal of uraemic solutes, is associated with poor patient quality of life and has a large carbon footprint. Innovative dialysis technologies such as portable, wearable and implantable artificial kidney systems are being developed with the aim of addressing these issues and improving patient care. An important challenge for these technologies is the need for continuous regeneration of a small volume of dialysate.

Blood-brain barrier perturbations by uremic toxins: Key contributors in chronic kidney disease-induced neurological disorders?

Chronic kidney disease is multifactorial and estimated to affect more than 840 million people worldwide constituting a major global health crisis. The number of patients will continue to rise mostly because of the aging population and the increased prevalence of comorbidities such as diabetes and hypertension. Patients with advanced stages display a loss of kidney function leading to an accumulation of, a.

CORAL Models for Drug-Induced Nephrotoxicity.

Drug-induced nephrotoxicity is a major cause of kidney dysfunction with potentially fatal consequences. The poor prediction of clinical responses based on preclinical research hampers the development of new pharmaceuticals. This emphasises the need for new methods for earlier and more accurate diagnosis to avoid drug-induced kidney injuries.

The Uremic Toxin Indoxyl Sulfate Accelerates Senescence in Kidney Proximal Tubule Cells.

Kidney fibrosis is the common final pathway of nearly all chronic and progressive nephropathies. One cause may be the accumulation of senescent cells that secrete factors (senescence associated secretory phenotype, SASP) promoting fibrosis and inflammation. It has been suggested that uremic toxins, such as indoxyl sulfate (IS), play a role in this.

Tubuloid culture enables long-term expansion of functional human kidney tubule epithelium from iPSC-derived organoids.

Kidney organoids generated from induced pluripotent stem cells (iPSC) have proven valuable for studies of kidney development, disease, and therapeutic screening. However, specific applications have been hampered by limited expansion capacity, immaturity, off-target cells, and inability to access the apical side. Here, we apply recently developed tubuloid protocols to purify and propagate kidney epithelium from d7+18 (post nephrogenesis) iPSC-derived organoids.

Bioengineered intestinal tubules as a tool to test intestinal biological efficacy of lettuce species.

Lettuce (Lactuca sativa) is one of the most consumed and cultivated vegetables globally. Its breeding is focused on the improvement of yield and disease resistance. However, potential detrimental or beneficial health effects for the consumer are often not targeted in the breeding programs.