In this post, I’d like to introduce the new Human liver Lysosomes developed by Sekisui-Xenotech that are indeed opening a new era in catabolism models.
NADPH RapidStart regeneration system for long-term metabolism
NADPH is a critical cofactor supporting numerous biochemical reactions. In ADME-Tox studies, NAD(P)H regeneration is strongly recommended when using drug metabolizing enzymes (ex. Cytochrome P450 (CYP), Flavin-containing MonoOxygenases (FMO)), Recombinant CYPs (incl. bactosomes) or cellular fractions (Microsomes, S9). Currently, the most simple and cost-effective way to regenerate the NAD(P)H in situ and enzymatically is to use the commercially-available RapidStart™ NADPH Regenerating System (Xenotech-Sekisui). [Read more…]
Toxicity Assessment of Co-Culture Human Systems
The inadequacy of animal models to predict human biology in the drug development process is becoming increasingly clear, due to species differences in uptake and metabolism at both cellular and organ levels.
As a result, there is a need for more human model systems to be incorporated earlier in research and development.
Innovative concepts such as “body on a chip” have been introduced, but the complexity and miniaturization of many of the formats has limited applicability on a commercial scale.
SciKon is developing tools that better recapitulate biological systems in bench-top cell culture formats, which are amenable to mass manufacturing (introduced recently in the post Cell Signaling isn’t static…your cell culture shouldn’t be either!). [Read more…]
Cell signaling isn’t static… your cell culture shouldn’t be either
Complex cell culture systems are emerging as key tools to improve physiological relevance of in vitro assay systems. There have been two main ways by which investigators attempt to improve mimicking of physiological conditions in cell and tissue culture. The first is to develop more complex model systems where two or more cell types are co-cultured in a 3D structure either separated by membranes or in spheroids [1]. The second is to incorporate fluidic-flow where the motion of the media itself has been shown to improve metabolic function and lifespan [2,3].
Despite the success of better recapitulating function at the cellular level using these two methods, neither of these approaches addresses the issue of the non-linear nature of the drug or toxicant exposure as is observed in an in vivo system [4]. As a result, the capacity to accurately predict in vivo pharmacokinetics and pharmacodynamics still falls short reaching at best 60-70% accuracy [5,6].
So what’s new in this area? We were interested to discover the following system, which we think will be of interest to many researchers. Let’s take a closer look at the characteristics and how it can be used. [Read more…]
Solute Carrier (SLC) Transporter studies made easy
EMA Guidance on transporters (Click to view)
Transporters have become increasingly important in drug development due to the major role they play in absorption, distribution and excretion of endogenous and exogenous compounds, as transporter-mediated drug-drug interactions (DDI) are associated with potential toxicological and pharmacological consequences. As shown in numerous publications, the effects of transporters on the pharmacokinetics of several drugs and associated DDI have been reported. Consequently, recent guidance documents released by the US FDA and European Medicines Agency (EMA) emphasize the importance of evaluating the potential of new drug candidates for transporter-mediated DDI.
Solute carrier (SLC) transporters are located in the small intestine, liver, kidney, blood-brain barrier, and so on. They play a role in the up-take of various drugs, as well as endogenous nutrients into cells and thus may influence the ADME properties of, or indeed adverse reactions to, a compound of interest. Thus, investigation of SLC transporters is expected to be helpful during drug development. [Read more…]
Rat liver tritosomes in the endosome-lysosome pathway
Rat liver tritosomes are hepatic lysosomes that have been loaded with Tyloxapol (Triton WR 1339), a non-ionic surfactant. Tyloxapol is taken up by hepatocytes through endocytosis and is trafficked to lysosomal compartments. Tyloxapol containing lysosomes exhibit decreased density and can be more efficiently isolated away from contaminating cellular organelles that have overlapping densities with native lysosomes (1-3). [Read more…]
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.
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!
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.