Is it a Poison, or is it a Life-Saving Drug?
by Bobby Buckheit, Karen Buckheit and Tracy Hartman
May 26, 2016
"Poison is in everything, and no thing is without poison. The dosage makes it either a poison or a remedy." Paracelsus, Father of Toxicology, 1493-1541
More than 500 years since Paracelsus articulated the relationship between poison and dosage, the concept remains the bedrock of toxicology and underlies the methods used to test potential drugs for safety and toxicity whether in vivo or in vitro. Technological advances in in vitro methods and the costs associated with in vivo studies have driven the increased use of in vitro and ex vivo approaches to preclinical drug safety testing.
ImQuest BioSciences has developed the ToxiSENS program to rapidly and efficiently analyze the in vitro and ex vivo toxicity of potential drugs, and answer the age old question in drug development: is this a potential drug, or is this simply a poison? We offer time-tested cytotoxicity assays performed using established cell lines and primary cells to evaluate the toxicity and off-target effects of new therapeutic entities. We additionally offer flow cytometric-based apoptosis assays, immunotoxicology testing and genomic toxicology services.
As we continue to develop our services, we highlight some of the cutting edge technological advances in the toxicology field presented this year at the Society of Toxicology Meeting in New Orleans. As the field evolves, ImQuest looks to enhance our capabilities utilizing these technologies:
Primary Hepatocyte Donor Variability: Primary human hepatocytes are still the gold standard for ADME/Tox evaluations, but have limited supply, inter-lot variability and the need to qualify each lot for CYP induction and transporter activity. Corning has developed HepatoCells that are derived from primary human hepatocytes that are a homogenous population of cells that maintain mature hepatocyte-like morphology with the use of only one medium for all phases of culturing and confirmed wild type genotype for common cytochrome P450s. The HepatoCell lot variability is 5-8 times lower than that experienced with primary hepatocytes.
3D Organ Models: The next advancement from organs on a chip is 3D bioprinting of human liver tissue by Organovo. They’ve developed bioink, comprised of primary hepatocytes, quiescent stellates and endothelial cells (not sinusoidal yet but working toward that) in a hydrogel. This is loaded into a 3D bioprinter cartridge that the grows compartmentalized, patterned human liver tissue in 96-well microtiter plates in approximately 60 hours. These exVive3D tissues last longer in culture than 2D sources to allow for chronic and extended dose studies.
Zebra Fish Animal Model: Zebrafish have become an increasingly popular animal model for toxicity evaluations and an alternative to the use of mammalian species. Zebrafish are known to have genetic similarity to humans; to date all proteins studied have a similar function in zebrafish and in mammals. The embryos are able to absorb chemicals in their aqueous environment, making drug delivery more effective and easier. The impact of any genetic mutations can be easily observed using non-invasive imaging since the embryos are transparent. Compared to rodents, Zebrafish also generate a high number offspring and grow and develop more quickly. Additionally, the use of zebra fish is cost-effective as they are less expensive, requiring less space per animal and a lower feeding cost.
Impedence endpoint/monolayers: Measuring cell impedance has become a valuable tool as a non-invasive assay endpoint for short- or long-term detection of cellular responses for toxicology, oncology and drug discovery. Impedance technology, such as the Bionas Discovery adcon reader that applies an alternative voltage to interdigitated electrodes of each well at a fixed frequency, provides cellular information about cell viability, morphology, adhesion/confluence, proliferation and membrane integrity.
Pig Heart Innovations: The Texas Heart Institute presented data on their early attempts to build a heart for transplantation. Using a decellularization technique to remove cells but leave the underlying porcine heart scaffold within a sterile, incubated bioreactor containing artificial lungs and blood pressure apparatus, human stem cells were then added and the cardiac progenitor cells grew into heart muscle that pumped on its own. The hurdles are the hundreds of billions of stem cells required, keeping the bioreactors sterile, and obtaining reliable, approved matrix sources (porcine at this time).
We look forward to next year's Society of Toxicology meeting, which is being held in nearby Baltimore, MD. The use of in vitro and ex vivo toxicology, and the development of novel technologies for toxicology assessment is a key component in the selection and identification of a lead compound. At ImQuest BioSciences, we specialize in services for the preclinical development of drugs, vaccines and biologics for the treatment and prevention of infectious disease, cancer and inflammatory disease. So let us help you determine if your lead compound is a poison, or is a game-changing, and lifesaving pharmaceutical product.Return to the Blog