Human Liver Subcellular Fractions

XenoTech offers the following human liver subcellular fractions:

• Cytosol
• Genotyped Microsomes
• Microsomes
• Mitochondria
• S9 Fraction

We feature pools that approach enzymatic activity rates typically expressed in the general population; however, individual samples are available upon request.  Contact us for assistance.

Overview of XenoTech's Human Liver Pools

• Pools are comprised of a large number of donors to yield results representative of an overall population and to minimize lot-to-lot variation.
• All pool preparations are protocol-driven and are prepared and characterized according to Standard Operating Procedures.
• The Study Director, Study Manager, and Quality Control Unit govern the quality of all human liver subcellular fractions.
• Microsomes from individual donors are prepared and fully characterized for enzymatic activities.  From these enzymatic data, pools can be designed that exhibit average activity rates for most cytochrome P450 enzymes.
• Human pools are prepared by pooling S9 fractions from individual liver donors.  This S9 pool can be characterized and sold as a product and/or further processed to microsomes and cytosol.  By pooling S9 rather than microsomes, a matching pool of microsomes and S9 can be offered.
• Typically, human pools are prepared in large lots (>60 liters of S9).
• Characterization assays for human pools are performed under conditions (i.e., substrate concentrations, incubation conditions, etc.) to obtain Vmax values.  CYP and UGT activity characterization assays are performed with XenoTech’s automated liquid handling and incubation system along with LC/MS/MS analysis.  Enzymatic activity assays are end-point assays performed in triplicate with saturating concentrations of the probe substrate.
• Typically, individual human liver samples are pooled such that each individual is significantly (but not necessarily equally) represented in the pool.
• Established acceptance criteria, and the use of positive controls, are used to determine the acceptability of both individual and pooled human microsomes.