The consequence of regional gradients of P-gp and CYP3A4 for drug-drug interactions by P-gp inhibitors and the P-gp/CYP3A4 interplay in the human intestine ex vivo.

Intestinal P-gp and CYP3A4 work coordinately to reduce the intracellular concentration of drugs, and drug-drug interactions (DDIs) based on this interplay are of clinical importance and require pre-clinical investigation. Using precision-cut intestinal slices (PCIS) of human jejunum, ileum and colon, we investigated the P-gp/CYP3A4 interplay and related DDIs with P-gp inhibitors at the different regions of the human intestine with quinidine (Qi), dual substrate of P-gp and CYP3A4, as probe. All the P-gp inhibitors increased the intracellular concentrations of Qi by 2.

P-gp activity and inhibition in the different regions of human intestine ex vivo.

Although intestinal P-glycoprotein (P-gp) has been extensively studied in vitro and in animals, its activity and the consequences of P-gp inhibition for drug disposition and toxicity in humans are still difficult to accurately extrapolate from these studies. Moreover, existing in vitro models do not take into consideration that the intestine is heterogeneous with respect to P-gp expression. Recently, we reported rat precision-cut intestinal slices (PCIS) as a physiological ex vivo model to study the regional gradient of P-gp activity and inhibition.

An integrative view of cisplatin-induced renal and cardiac toxicities: Molecular mechanisms, current treatment challenges and potential protective measures.

Cisplatin is currently one of the most widely-used chemotherapeutic agents against various malignancies. Its clinical application is limited, however, by inherent renal and cardiac toxicities and other side effects, of which the underlying mechanisms are only partly understood. Experimental studies show cisplatin generates reactive oxygen species, which impair the cell's antioxidant defense system, causing oxidative stress and potentiating injury, thereby culminating in kidney and heart failure.

Intracellular RIG-I Signaling Regulates TLR4-Independent Endothelial Inflammatory Responses to Endotoxin.

Sepsis is a systemic inflammatory response to infections associated with organ failure that is the most frequent cause of death in hospitalized patients. Exaggerated endothelial activation, altered blood flow, vascular leakage, and other disturbances synergistically contribute to sepsis-induced organ failure. The underlying signaling events associated with endothelial proinflammatory activation are not well understood, yet they likely consist of molecular pathways that act in an endothelium-specific manner.

The Consequence of Drug-Drug Interactions Influencing the Interplay between P-Glycoprotein and Cytochrome P450 3a: An Ex Vivo Study with Rat Precision-Cut Intestinal Slices.

P-glycoprotein (P-gp) and cytochrome P450 3A (CYP3A) are differentially expressed along the intestine and work coordinately to reduce the intracellular concentration of xenobiotics and the absorption of orally taken drugs. Drug-drug interactions (DDIs) based on P-gp/CYP3A interplay are of clinical importance and require preclinical investigation. We investigated the P-gp/Cyp3a interplay and related DDIs with different P-gp inhibitors in the various regions of the rat intestine ex vivo using precision-cut intestinal slices (PCIS) with quinidine (Qi), a dual substrate of P-gp and Cyp3a, as the probe.

Precision-cut intestinal slices: alternative model for drug transport, metabolism, and toxicology research.

Introduction: The absorption, distribution, metabolism, excretion and toxicity (ADME-tox) processes of drugs are of importance and require preclinical investigation intestine in addition to the liver. Various models have been developed for prediction of ADME-tox in the intestine. In this review, precision-cut intestinal slices (PCIS) are discussed and highlighted as model for ADME-tox studies.

Adjusting the DNA Interaction and Anticancer Activity of Pt(II) N-Heterocyclic Carbene Complexes by Steric Shielding of the Trans Leaving Group.

Five platinum(II) complexes bearing a (1,3-dibenzyl)imidazol-2-ylidene ligand but different leaving groups trans to it were examined for cytotoxicity, DNA and cell cycle interference, vascular disrupting properties, and nephrotoxicity. The cytotoxicity of complexes 3a-c increased with the steric shielding of their leaving chloride ligand, and complex 3c, featuring two triphenylphosphanes, was the most efficacious, with submicromolar IC50 concentrations. Complexes 3a-c interacted with DNA in electrophoretic mobility shift and ethidium bromide binding assays.

Rat precision-cut intestinal slices to study P-gp activity and the potency of its inhibitors ex vivo.

Rat Precision-Cut Intestinal Slices (PCIS) were evaluated as ex vivo model to study the regional gradient of P-gp activity, and to investigate whether the rank order of inhibitory potency of P-gp inhibitors can be correctly reproduced in this model with more accurate IC50 values than with current in vitro models. PCIS were prepared from small intestine (duodenum, jejunum, ileum) and colon. Rhodamine 123 (R123) was used as P-gp substrate, while verapamil, cyclosporine A, quinidine, ketoconazole, PSC833 and CP100356 were employed as P-gp inhibitors.

Precision-cut rat, mouse, and human intestinal slices as novel models for the early-onset of intestinal fibrosis.

Intestinal fibrosis (IF) is a major complication of inflammatory bowel disease. IF research is limited by the lack of relevant in vitro and in vivo models. We evaluated precision-cut intestinal slices (PCIS) prepared from human, rat, and mouse intestine as ex vivo models mimicking the early-onset of (human) IF.

Improved synthesis of N-benzylaminoferrocene-based prodrugs and evaluation of their toxicity and antileukemic activity.

We report on an improved method of synthesis of N-benzylaminoferrocene-based prodrugs and demonstrate its applicability by preparing nine new aminoferrocenes. Their effect on the viability of selected cancer cells having different p53 status was studied. The obtained data are in agreement with the hypothesis that the toxicity of aminoferrocenes is not dependent upon p53 status.

Consequences of Mrp2 deficiency for diclofenac toxicity in the rat intestine ex vivo.

The non-steroidal anti-inflammatory drug diclofenac (DCF) has a high prevalence of intestinal side effects in humans and rats. It has been reported that Mrp2 transporter deficient rats (Mrp2) are more resistant to DCF induced intestinal toxicity. This was explained in vivo by impaired Mrp2-dependent biliary transport of DCF-acylglucuronide (DAG), leading to decreased intestinal exposure to DAG and DCF.

Precision cut intestinal slices are an appropriate ex vivo model to study NSAID-induced intestinal toxicity in rats.

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used therapeutic agents, however, they are associated with a high prevalence of intestinal side effects. In this investigation, rat precision cut intestinal slices (PCIS) were evaluated as an ex vivo model to study NSAID-induced intestinal toxicity. Firstly, PCIS were incubated with 0-200 μM diclofenac (DCF), one of the most intensively studied NSAIDs, to investigate whether they could correctly reflect the toxic mechanisms.

Diclofenac toxicity in human intestine ex vivo is not related to the formation of intestinal metabolites.

The use of diclofenac (DCF), a nonsteroidal anti-inflammatory drug, is associated with a high prevalence of gastrointestinal side effects. In vivo studies in rodents suggested that reactive metabolites of DCF produced by the liver or the intestine might be responsible for this toxicity. In the present study, precision-cut intestinal slices (PCIS) prepared from the jejunum of 18 human donors were used as an ex vivo model to investigate whether DCF intestinal metabolites are responsible for its intestinal toxicity in man.

Nanoparticle formulation of a poorly soluble cannabinoid receptor 1 antagonist improves absorption by rat and human intestine.

The inclusion of nanoparticles dispersed in a hydrophilic matrix is one of the formulation strategies to improve the bioavailability of orally administered Biopharmaceutics Classification System (BCS) class II and IV drugs by increasing their dissolution rate in the intestine. To confirm that the increased dissolution rate results in increased bioavailability, in vitro and in vivo animal experiments are performed, however, translation to the human situation is hazardous. In this study, we used a range of in vitro and ex vivo methods, including methods applying human tissue, to predict the in vivo oral bioavailability of a model BCS class II CB-1 antagonist, formulated as a nanoparticle solid dispersion.

Bilitranslocase is involved in the uptake of bromosulfophthalein in rat and human liver.

Hepatic disposition of bromosulfophthalein (BSP), bilirubin and bile salts partially overlap, as these anions share both uptake and excretion mechanisms. Multiple organic anion transporters mediate hepatic BSP uptake, i.e.

Analysis of gene expression changes to elucidate the mechanism of chilling injury in precision-cut liver slices.

The exact mechanism of chilling injury (by a decrease of temperature to sub-physiological values), especially in the intact organ, is yet unknown. Precision-cut liver slices (PCLS), which closely resemble the organ from which they are derived, are an ideal in vitro model to study the mechanism of chilling injury in the intact organ. In the present study we were able to separate chilling injury from other damaging events such as cryoprotectant toxicity and ice-crystal injury and performed micro-array analysis of regulated genes.

Evaluation of the intestinal toxicity and transport of xenobiotics utilizing precision-cut slices.

1.The precision-cut intestinal slice (PCIS) technology is a relatively new addition to the battery of in vitro assays for evaluation of xenobiotic toxicity, metabolism, and transport. 2.

Cryopreservation of precision-cut tissue slices.

1.Cryopreservation of precision-cut tissue slices (PCTS) would have many advantages for drug development and would encourage more extensive use of the PCTS preparation. 2.

Effects of cryoprotectant addition and washout methods on the viability of precision-cut liver slices.

Successful vitrification of organ slices is hampered by both osmotic stress and chemical toxicity of cryoprotective agents (CPAs). In the present study, we focused on the effect of osmotic stress on the viability of precision-cut liver slices (PCLS) by comparing different CPA solutions and different methods of loading and unloading the slices with the CPAs. For this purpose, we developed a gradient method to load and unload CPAs with the intention of minimizing sudden changes in osmolarity and thereby avoiding osmotic stress in the slices in comparison with the commonly used step-wise loading/unloading approach.

Precision-cut intestinal slices as in vitro tool for studies on drug metabolism.

The role of the intestine in drug metabolism has long been underestimated as a consequence of the technical difficulty to discern the role of the intestine from that of the liver in in vivo experiments and of the lack of in vitro models that are sufficiently viable and fully representing the physiology and anatomy of the intestine. Recently the precision-cut slice model, which is widely used for liver and kidney, was also adapted for the small and large intestine. In this review the application of precision-cut intestinal slices (PCIS) for research in drug metabolism and transport is discussed.

Transport of the coumarin metabolite 7-hydroxycoumarin glucuronide is mediated via multidrug resistance-associated proteins 3 and 4.

Coumarin (1,2-benzopyrone) is a natural compound that has been used as a fragrance in the food and perfume industry and could have therapeutic usefulness in the treatment of lymphedema and different types of cancer. Several previous pharmacokinetic studies of coumarin have been performed in humans, which revealed extensive first-pass metabolism of the compound. 7-Hydroxycoumarin (7-HC) and its glucuronide (7-HC-G) are the main metabolites formed in humans, and via this route, 80 to 90% of the absorbed coumarin is excreted into urine, mainly as 7-HC-G.

On-line HPLC analysis system for metabolism and inhibition studies in precision-cut liver slices.

A novel approach for on-line monitoring of drug metabolism in continuously perifused, precision-cut liver slices (PCLS) in a microfluidic system has been developed using high-performance liquid chromatography with UV detection (HPLC-UV). In this approach, PCLS are incubated in a microfluidic device made of poly(dimethylsiloxane) (PDMS) by continuous, single-pass perifusion with fresh medium. Two syringe pumps are incorporated into the system to infuse substrates or inhibitors at varying concentrations into the perfusion medium just before the chip entrance.

Preparation and incubation of precision-cut liver and intestinal slices for application in drug metabolism and toxicity studies.

Precision-cut tissue slices (PCTS) are viable ex vivo explants of tissue with a reproducible, well defined thickness. They represent a mini-model of the organ under study and contain all cells of the tissue in their natural environment, leaving intercellular and cell-matrix interactions intact, and are therefore highly appropriate for studying multicellular processes. PCTS are mainly used to study the metabolism and toxicity of xenobiotics, but they are suitable for many other purposes.

Reduced ischemia-reoxygenation injury in rat intestine after luminal preservation with a tailored solution.

Background: The intestine is extremely sensitive to ischemic preservation and reoxygenation injury. Current vascular perfusion and cold storage with University of Wisconsin (UW) solution neglect the intestinal lumen and the ongoing mucosal metabolism during hypothermia. This study was designed to test the effects of luminal preservation with an alternative preservation solution in addition to the common vascular flush with UW solution on graft viability after preservation and ex vivo reoxygenation.

Targeted transfection increases siRNA uptake and gene silencing of primary endothelial cells in vitro--a quantitative study.

Applications of small-interfering RNA (siRNA) call for specific and efficient delivery of siRNA into particular cell types. We developed a novel, non-viral targeting system to deliver siRNA specifically into inflammation-activated endothelial cells. This was achieved by conjugating the cationic amphiphilic lipid SAINT to antibodies recognizing the inflammatory cell adhesion molecule E-selectin.