You may have heard about the patented CryostaX® format of hepatocyte pellets, but do you know why SEKISUI XenoTech and countless other researchers have made the switch from traditional hepatocyte preparations to pellets? Depending on who you ask the reasons will vary, from the needs of the study to simple convenience. In this post, let’s look at the primary factors so you can see for yourself why you should make the switch.
Pooling – Maximize metabolic activities by limiting Hepatocyte cryoinjury
Cryopreservation and thawing of primary hepatocytes causes inherent damage to the cells. Traditional pooling methods require cells to undergo two separate cryopreservation and thaw steps, leading to increased cryoinjury and decreased metabolic activity.
The patented CryostaX® hepatocyte cryopreservation process eliminates one of those steps. Individual donor hepatocytes are cryopreserved into CryostaX® pellets, instead of to the inside of a vial. Those pellets can then be easily combined as required, without having to thaw, mix, and re-cryopreserve a second time.
As you can see in a poster presented by Sekisui Xenotech at the 9th International ISSX Meeting in 2010, data indicates that minimizing cryoinjury leads to a modest conservation of CYP450 and SULT activities and has significant benefits to UGT activity. So why choose hepatocytes with unnecessary cryoinjury?
Hepatocyte pellets enable fast, no-cost customization of Human hepatocyte pools
As mentioned above, single-donor CryostaX® hepatocyte pellets can be combined into customized pools very easily, which interprets as quickly at no additional cost. Once the proposed pool is approved by the customer, the pool can be typically made and out the door within one and a half weeks. This allows scientists to create pools with up to 20 donors in a standard vial based on the specific needs of their study. Each individual donor is extensively characterized, so custom pools can be designed based on donor demographics, medical histories, genotyping, metabolic activity and more. Common options include:
- Specific Enzyme Activity
- Pool Size
- Disease State
- Age, Ethnicity &/or Gender
- Alcohol, Tobacco &/or Drug Use
Use with microsome stable, slower turnover compounds
Compounds that exhibit high metabolic stability in suspension hepatocytes and subcellular fractions (S9, microsomes and cytosol) can be a challenge for ADME scientists, as they are traditionally limited to an incubation window of up to 6 hours depending on the test system, taking advantage of the time when they are the most metabolically active and can generate quality data. As previously mentioned, the absence of the second freeze/thaw step when pooling results in less cryoinjury. Less cryoinjury leads to higher quality cells. When used with SEKISUI XenoTech’s optimized medium and protocol, plateable CryostaX human hepatocytes can be cultured for up to 48 hours without a medium change, giving a significantly extended incubation window in which to collect metabolism data (Fig. 1). We successfully used plated hepatocytes to measure substrate loss and calculate intrinsic clearance, even for notoriously low-turnover small molecule drugs. When compared to alternative methodologies used to assess low-turnover compound metabolism, CryostaX® generates comparable metabolism data in a format that is easier to use and more cost effective. (Fig. 2). Discounted test vials can be ordered to evaluate and qualify specific lots for this purpose if you have an applicable compound.
Hepatocyte pellets are easier to use and reduce the risk of contamination
CryostaX® hepatocytes also eliminate the need for water baths that are traditionally required to thaw cryopreserved hepatocytes and release them from the vial. By removing water baths in or near culture hoods and incubators, a significant source of tissue culture contamination can be decreased or even eliminated. CryostaX® hepatocytes can be taken directly from nitrogen storage and simply poured into pre-warmed thaw medium. Watch the Hepatocyte Thawing Demo Video to see them in use.
In addition to negating potential contamination, researchers have stated that they enjoy the increased efficiency and performance consistency from eliminating the thawing step. As there is no longer a danger of cell damage from over-thawing, users have expressed increased confidence in using CryostaX® hepatocytes because of reduced or eliminated variability due to differences in user skill levels and experience.
All of the benefits above are just the beginning. What are the other notable features of CryostaX®?
- The only single-freeze, pooled plateable human hepatocyte product on the market
- Reduce costs by customizing Assured Minimum Yield (AMY) to only what you need
- Pooling pellets leads to each donor contributing more equally to the pooled population and metabolic activity
- Pooled lots are extensively characterized for metabolism and uptake transport, with CYP induction (10-Donor Attaching Pool)
- Highly competitive pricing
- Large lot sizes
So even when researchers don’t have specific study requirements that would benefit from CryostaX®, they’re still choosing to switch to a pellet format for the other benefits as stated in these comments from CryostaX® customers:
“We have used 2 different lots of Human 10 donor pooled CryostaX and overall the viability has been very good. Typically I have observed close to or above the noted viability from the product specification sheets. In addition the yields per vial have been consistent to the product sheets. What is most helpful are the enzyme activity numbers as our in vitro clearance results match well with activity results provided by XenoTech. The CryostaX pellets were very easy to work with as there was no need for a thawing step.”
“I found the CryostaX very easy to work with and I’m definitely comfortable using them. The onsite training we received was excellent but I think the video and protocol would be sufficient for many users.”
“Whoa, I love the cryo pellets. That really takes the ‘art’ out of thawing. You guys should do that with all of your cryo, I’m not kidding.”
Reactions such as these are why Sekisui Xenotech are expanding the CryostaX® options beyond individual-donor and pooled human hepatocytes for suspension or plating. You can also obtain monkey, mouse and rat hepatocyte pellets and more options will continue to be added to the CryostaX® lineup in the future.
Dr. Chris Bohl, Global Technical Support Manager for Products at Sekisui Xenotech, commented, “We’re excited about the convenience our CryostaX hepatocytes offer for our customers. We have hepatocytes available from numerous species in many formats to fit the needs of different types of research, but the patented, unique format of CryostaX is truly a game-changer for the increased efficiency, unparalleled flexibility, and greater utility they provide for drug development.”
Special thanks to Michael Millhollen and Dr Chris Bohl, our partners at Sekisui Xenotech for sharing this post content with us.
Keen to start using hepatocyte pellets?
Access the full range of hepatocyte pellets and all of Sekisui Xenotech’s products through Tebubio in Europe – reach out to your local Tebubio office near to find the best all-round solutions to facilitate your research.