Cellular models for studying the human urogenital system

The urogenital system is the organ system of the reproductive organs and the urinary system. These are grouped together because of their proximity to each other, their common embryological origin and the use of common pathways, like the male urethra.

Today, I’ll be taking a look at human primary cells derived from urogenital organs (and in one of my next posts, we’ll explore models for the digestive system.

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Hepatic Cellular Models

A wide range of in vitro models are used in preclinical drug testing for the investigation of ADME-Tox (Absorption, Distribution, Metabolism, Excretion and oxicity) properties of New Chemical Entities (NCEs). The liver is the main organ with regards to ADME-Tox, it’s the place of more than 500 different functions, including: metabolism of lipids, carbohydrates, and vitamins, detoxification, production of bile, albumin, fibrinogen, globulin, etc (1). The liver lobule is composed of parenchymal cells (hepatocytes) and nonparenchymal cells (Kupffer cells, hepatic stellate cells, and sinusoidal endothelial cells).

Hepatocytes – the Gold Standard

Hepatocytes represent 80% of liver volume. Hepatocytes are commonly used in drug discovery and preclinical drug development to perform experiments requiring intact cellular systems. Intact hepatocytes contain the major hepatic drug-metabolizing enzymes required to study the four categories of xenobiotic biotransformation: hydrolysis, reduction, oxidation and conjugation.

Because of these enzymes, hepatocytes provide a viable and cost-effective alternative to in vivo testing. [Read more…]

5 most popular posts in ADME-Tox in 2014!

Take a look at the 5 posts on our blog in the field of ADME-Tox that saw the most visits in 2014!

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Predicting CYP induction in stable cell lines

Assessing gene transcription as an endpoint for determining induction of drug metabolizing enzymes and transporters has become the “method of choice” in the FDA’s latest draft Guidance for Industry drug interaction studies. Increased gene transcription due to NCE exposure can be determined by two distinct methods, nuclear receptor activation and changes in mRNA levels in primary hepatocyte cultures.

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Biomimetic Chemistry, a new route for metabolite synthesis

In 2008, the FDA released guidance for drug metabolite safety testing (MIST), emphasizing the importance of metabolite toxicity testing in the drug development process. Indeed, drug toxicity, which accounts for roughly 40% of clinical drug failures, is a leading cause of the high drug attrition rates that have contributed to the skyrocketing drug development costs witnessed over the past few decades.

Traditionally, drug metabolites have been both difficult and hugely expensive to synthesize. Conventional methods of metabolite synthesis, such as those that employ the use of microsomes (while they have proven valuable as a predictive tool, their productive capabilities could be limited by NCE stability) or synthetic chemistry, can be extremely costly and time consuming. Consequently, drugmakers often choose to forego metabolite synthesis (and subsequent metabolite toxicity testing ) early on in the drug development process, opting instead to wait until lead compounds are further along in development before carrying out these essential functions. This decision, perceived to be a calculated risk, ultimately comes at huge price, as drug makers lose millions each year on investments in lead drug candidates that eventually turn out to be failures due to toxicity.

Biomimetic Chemistry, on the other hand, possesses the advantages of both chemistry and biology and is thus a much more efficient tool for metabolite synthesis. In fact, with biomimetic chemistry, large scale metabolite generation is enabled in one step, by mimicking and optimizing the same biotransformation reactions that occur in the liver. [Read more…]

Plateable Hepatocytes… the “one cell type doesn’t fit all” syndrome

Hepatocytes are commonly used in drug discovery and preclinical drug development to perform experiments requiring intact cellular systems. Intact hepatocytes contain the major hepatic drug-metabolizing enzymes required to study the four categories of xenobiotic biotransformation: Hydrolysis, Reduction, Oxidation and Conjugation. Because of these enzymes, hepatocytes provide a viable and cost-effective alternative to in vivo compound testings.

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6 tips for thawing hepatocytes

Cryopreserved hepatocytes contain the major hepatic drug-metabolizing enzymes required to study the four categories of xenobiotic biotransformation: hydrolysis, reduction, oxidation and conjugation. Cryopreserved hepatocytes are ready when you are. A simply quick-thaw protocol is performed to remove cryoprotectant and have viable cells… However, the functionality and the viability of these cells can be impaired by an incorrect thawing procedure… [Read more…]

Maximise availability & reduce variability in hepatocytes studies

ADMEPooled human hepatocytes are a preferred test system in many drug discovery and development applications which require intact cellular systems for in vitro testing. Intact hepatocytes contain the major hepatic drug-metabolizing enzymes and co-factors required to evaluate the metabolism and potential drug-drug interactions of drug candidates effectively.

Over the last decade, improvements of cryopreservation technologies make possible using cryopreserved human hepatocyte more conveniently. Pooled cryopreserved hepatocytes reduce the inter-individual differences and polymorphic distribution of liver enzymes. However, this is crucial to carefully select a pool according to its performance but also the application used for. [Read more…]

Stellate cells – models for liver studies

Introduction

Hepatic stellate cells (HSC, also known as perisinusoidal cells or Ito cells), are liver-specific mesenchymal cells found in the space of Disse. HSC maintain interactions with sinusoidal endothelial cells and hepatic epithelial cells. The stellate cells are involved in liver physiology and fibrogenesis (formation of scar tissue in response to liver damage). [Read more…]

Activation & de-activation pathways of hepatic fibrosis

Liver fibrosis is the result of an imbalance between production and dissolution of extracellular matrix. It has been described that Stellate cells, liver myofibroblasts, and bone marrow derived cells converge in a complex interaction with hepatocytes and immune cells to induce response to liver injury.

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