Primary human hepatocytes are essential tools for drug discovery, ADME/DMPK, and toxicology studies — but it is important to remember that not all lots are the same. Taking time to ask key questions up front about donor history, histopathology, hepatocyte function, and other issues can help researchers get the best match for each project. Here are a few issues to consider:
- Plateability, which describes the attachment efficiency of each batch of cells. “Not all batches will attach well to standard plasticware or collagen-coated 96-well plates, which is the most commonly used platform among most hepatocyte users,” said LifeNet Health Chief Scientist Ed LeCluyse, PhD. Issues to consider during and after plating hepatocytes include proper handling, assessing optimal seeding density, monolayer confluence, morphological features and hepatic functions over time, and whether a lot is designated for suspension vs. plateable applications.
- Tissue and cell sourcing. Access to quality human cells from both healthy and diseased donors is crucial for toxicity testing, ADME, and disease modeling. While there are well established guidelines for tissue banks, these standards often do not cover all aspects related to preclinical applications. The lack of universal protocols for recovering, processing, preserving, documenting, and qualifying tissues can make it challenging for researchers to determine the best source and specifications for lot selection. One solution is to look for sources with a vertically integrated process that can offer more assurances and information across the donation continuum – including consent, recovery, preservation, isolation, characterization, and quality control.
- The breadth and depth of donor information. While it is understood that hepatocyte lots will vary based on a donor’s demographics and health status, other factors can also come into play when it comes to ensuring a good fit for a given study. Researchers should look for detailed information, including medical history, laboratory blood values, warm/cold ischemia times, and exposure to infectious diseases.
- Pathology assessment. Researchers should ensure histopathology scores are available for fibrosis, inflammatory activity, steatosis, hepatocellular ballooning, non-alcoholic fatty liver disease, and nonalcoholic steatohepatitis. Pathology notes can also be helpful.
- Viability and yield of recovered hepatocytes. This represents cell recovery, survival, and integrity after cryopreservation. “The post-thaw viability can vary significantly between hepatocyte batches which impacts their suitability for different culture formats, including 2D vs 3D platforms, and applications,” Dr. LeCluyse said. Typical yields are between 5 and 10 million viable cells per vial for most hepatocyte lots, but with today’s co-culture and microphysiological technologies, the optimal number of cells required for a given application may be below or above this range.
- Enzyme profiling. Researchers should look for information about major CYP enzymes, which are important in drug metabolism and drug-drug interactions, as well as information for other key substrates, such as 7-ethoxycoumarin, the industry standard for phase 2 metabolism. “Make sure you’re asking about the enzyme profiling data and whether it represents normal or average values, as well as indications of polymorphic alleles,” Dr. LeCluyse said.
- Assessment of induction potential. While this has evolved over the years, the latest recommendations from working groups call for a ten-fold increased mRNA expression of CYP3A4, relative to a vehicle control, after treatment with a prototypical inducer, such as rifampicin.
- Optional or custom data. Researchers may find it helpful to have additional information to assess whether a hepatocyte lot will fit their specific application or express a specific biomarker. This can include transporter expression, receptor pathways, disease markers, or other metabolic pathways of interest such as FMOs or AOs. Finding the right partner who has the knowledge and expertise to identify and help qualify suitable hepatocyte lots can greatly impact the likelihood of success.
Taking time up front to consider the many factors that can influence hepatocyte performance can pay off over the course of a project. LifeNet Health LifeSciences is committed to offering unparalleled partnership and service, starting with expert help with lot selection. We also offer post-purchase follow-up, including troubleshooting advice from our world-class scientists.