Human Kidney Microsomes, S9, and Cytosol for Preclinical Drug Development

Human kidney microsomes and S9 are commonly used in drug discovery and preclinical drug development to evaluate in vitro drug metabolism. Kidney microsomes are supplied in 250 mM sucrose buffer. S9 and cytosolic fractions are supplied in 50 mM TRIS-HCI, (pH 7.4 at 4ºC) containing 150 mM KCI and 2 mM EDTA.

Using Kidney (Renal) Subcellular Fractions for In Vitro Drug Metabolism Assays

Kidneys express relatively high levels of CYP4A and CYP4B enzymes, efflux transporter P-glycoprotein (P-gp, MDR1), and phase II drug-metabolizing enzymes including UGT1A6, UGT2B7, SULT1C2, and DT-diaphorase (NQO1). We offer human kidney subcellular fractions of the highest quality, specially prepared to maintain high levels of enzymatic activity, and our offerings ensure consistency between assays using different subcellular test systems through availability of matching S9 and cytosol preparations from the same donor pool. Furthermore, our proprietary preparation methods maximize stability over multiple freeze-thaw cycles (see table below). 

Make sure your microsomes and S9 fractions are properly activated

For best results from assays using microsomes and S9 fractions, we recommend using NADPH regeneration to support high metabolism levels by ensuring that the NADPH levels are not a limiting factor in your incubations. Our preferred system, RapidStart^TM , uses an enzymatic reaction that converts NADP to NADPH, which is then used as a cofactor by CYPs and oxidized back to NADP, and the cycle continues ensuring stable NADPH levels throughout the incubation. RapidStart^TM NADPH regeneration is easily activated by simply adding water. Our easy-to-use formula is the most convenient and flexible NADPH regenerating system you’ll find, allowing users to easily tailor the system’s capability by simply varying the amount of water added. RapidStart^TM is perfect for long- and short-term incubations and supports the function of recombinant enzymes and subcellular fractions, allowing you to achieve the most accurate and reliable data during your in vitro assays.

Don’t see what you need? Other preparations can be made available!

If you require human cell fractions outside of what we carry as standard inventory, custom subcellular fractions can be easily ordered to meet the specific needs of your study. Capabilities include additional characterization assays, donor pools customized to meet specific disease-state or demographic criteria, as well as alternative options for buffer and/or protein concentration. Our highly experienced team can also prepare fractions using protocols sourced by the customers or create a tailored protocol to satisfy special requests. See our Custom Products page for examples of past custom preparations or get in touch with a specialist to find out how we can meet your needs.