Frequently Asked Questions
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Cryopreserved Hepatocytes
Is it possible to get donor information for human-derived products?
Certain demographics are available on all human donors, including sex, age, race, limited medical history (major illnesses, recent medications, etc.) and limited social history (smoking, alcohol, drug habits, etc.). Information that may reveal the identity of the donor is not available.
How do you prepare your cryopreserved hepatocytes?
The liver tissue is perfused and the cells are isolated. Percoll® centrifugation is performed to improve the cell viability. Finally, the cells are cryopreserved as described in our manuscript: "Effect of cryopreservation on cytochrome P450 enzyme induction in cultured rat hepatocytes," A Madan, R DeHaan, D Mudra, K Carroll, E LeCluyse and A Parkinson, Drug Metab Dispos, 27:327-335, 1999.
How should cryopreserved hepatocytes be handled?
Hepatocytes should be stored in liquid nitrogen vapor phase. They should be thawed in accordance with our thawing protocol, which is shipped with your hepatocytes. For best results, we recommend that the cells be isolated with our Hepatocyte Isolation Kit, as described in our CD-ROM video tutorial.
How are cryopreserved hepatocytes shipped?
The hepatocytes are shipped in a "dry dewar." This is a cryogenic shipper containing vapor phase liquid nitrogen. The containers include a return airbill for easy return to XenoTech.
What is the advantage of purchasing hepatocytes based on assured minimum vs. average yield?
Hepatocytes sold by average yield can leave the end user with less viable cells than expected. With Assured Minimum Yield (AMY) categories, the user knows how many viable cells to expect after thawing. This added detail allows our customers to plan their purchases to meet their study needs. Vials are priced according to their AMY category, so customers also get what they pay for.
Some cryopreserved human hepatocyte vials contain fewer viable cells than others; should I be concerned about their performance?
No. Cell yield should not be used as a predictor of the enzymatic activity of cryopreserved human hepatocytes, but rather as a tool for the end user to predict how many cells will be available to perform the required tests. See our study on the topic here.
Can cryopreserved hepatocytes be used for metabolism and induction studies?
This table provides a quick reference for the potential use of cryopreserved hepatocytes from different species.
Species |
Recommended Application |
Metabolism Studies
(short-term incubations) |
Induction Studies
(long-term incubations) |
Human |
Yes |
Sometimes * |
Monkey |
Yes |
Not recommended * |
Dog |
Yes |
Not recommended * |
Rat |
Yes |
Yes |
* Most cryopreserved human, monkey and dog hepatocytes do not attach in culture; therefore, they may not be suitable for enzyme induction studies. Please
contact us for availability of inducible human hepatocytes.
Can I order pooled human hepatocytes?
XenoTech offers individual human hepatocytes in a “Pooling Category.” Each vial has an assured minimum viable yield of 1.0 x 106 cells based on post-thaw data. This provides a cost-effective method for purchasing several different individuals human vials, which can be pooled upon thawing.
Why does XenoTech sell human hepatocytes by category?
Categories give our customers a greater range of choices. By grouping cells by yield for appropriate pricing, we ensure that you get the most for your money with each vial.