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Why Switch to Hepatocyte Pellets?

You may have heard about the patented CryostaX® format of hepatocyte pellets, but do you know why XenoTech and countless other researchers have made the switch to pellets from traditional hepatocyte preparations? The reasons vary depending on who you ask, from the needs of the study to simply convenience, so we’re going to outline the primary factors and let you decide for yourself.

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 in any combination without having to thaw, mix, and re-cryopreserve a second time.

As you can see in a poster that we presented 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?

Pooling: Fast No-Cost Customization of Human Hepatocyte Pools

As mentioned above, single-donor CryostaX® hepatocyte pellets can be combined into customized pools very easily, and easy means 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
  • BMI
  • Disease State
  • Age, Ethnicity &/or Gender
  • Alcohol, Tobacco &/or Drug Use
  • Serologies

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 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 are available to evaluate and qualify specific lots for this purpose if you have an applicable compound.