A Bioengineered Microliver Platform
Primary hepatocytes display a precipitous decline in phenotypic functions when cultured in a sandwich of extracellular matrix proteins (i.e. collagen, Matrigel). This severely limits the ability of these model systems to accurately predict clinical outcomes. Hepregen’s HepatoPac platform is a bioengineered, in vitro co-culture with precise cyto-architecture and optimal stromal interactions that displays high levels of liver-specific functions for several weeks. Microfabrication and tissue engineering technologies have been combined to create a precise, organized and miniaturized human liver model. Micropatterned industry-standard multiwell plates contain tiny colonies of organized primary hepatocytes surrounded by supportive stroma resulting in a highly functional model of the in vivo human liver. HepatoPac technology is available to researchers via Hepregen DMPK and Toxicology Services.
- Long-term Stability and Functionality (several weeks)
- Highly Organized Architecture
- Modular Design
- Miniaturized in an Industry- standard Multiwell Format
- Broad Utility in Drug Development (drug discovery and toxicity screening)
- High Content, Predictive Data
- Cost Savings
- No Major Procedure Change
- No Specialized Instrumentation Required
- Minimal Compound Usage
HepatoPac's ability to closely mimic the human liver's in vivo functionality makes it well-suited for a broad range of applications.
- Preclinical Toxicity Screening and Mechanistic/Investigative Toxicology
- Metabolite Identification
- Transporter-Mediated Drug Uptake and Biliary Efflux
- Clearance Predictions
- Drug-Drug Interactions
- Efficacy Assessment
Within the HepatoPac; co-culture, primary hepatocytes are organized into colonies of prescribed, optimized dimensions using microfabrication tools and subsequently surrounded by supportive, non-parenchymal cells. The HepatoPac microliver structures result in a “high-fidelity tissue model” which closely mimics the functions of a human liver. HepatoPac cultures secrete albumin, synthesizes urea, display functional bile canaliculi, and metabolize compounds using active Phase I and Phase II drug metabolism enzymes (1). The gene expression profiles of the microliver structures are very similar to those found in fresh liver cells. The tiny liver colonies are viable and functional in vitro for up to six weeks for the human model or ten weeks for non-human models, such as rodent models. The HepatoPac platform has been shown to outperform conventional culture models (i.e. collagen gel sandwich, Matrigel overlay) in the magnitude and longevity of liver-specific functions (2).
Non-Human HepatoPac Models
Pre-clinical animal species models of HepatoPac (eg. Rat, Monkey, and Mouse) have been developed for refining and reducing live animal testing. Additional in vitro animal liver model systems, such as dog and guinea pig, are under development.
Industry Need & HepatoPac Solution
Species-specific variations in organ functions between animals and humans can be significant, especially in liver-specific metabolic pathways (i.e. CYP450). This, along with other factors, can limit the utility of animal models for predicting human-specific responses. Isolated primary human hepatocytes in adherent culture are widely considered to be the most suitable for in vitro testing (3). They are relatively simple to use and maintain an intact cellular architecture with complete, undisrupted enzymes and cofactors. Conventional culture models used for industrial ADME/Tox screening expose primary hepatocytes to tumor-derived Matrigel and/or collagen-I gels (sandwich cultures). When used with near confluent monolayers, these models allow better retention of hepatocyte cyto-architecture and activities of specific CYP450s for several more days (3-5 days) than that observed in cultures grown on rigid collagen (3). Sandwich cultures, however, are inherently unstable in their phenotypic functions and their short-term functionality does not allow for chronic drug metabolism and toxicity to be measured. The current sensitivity of sandwich cultures, even with highly sensitive high content imaging readouts, is estimated to be approximately 50-60% (i.e. false negative rate of 40-50%) (4). Furthermore, sandwich cultures are notoriously difficult to scale down to 24- and 96-well formats well-suited for medium-to-high throughput screening due to instability of the overlaying gels and heterogeneity in monolayer confluence and cellular viability across the culture well, becoming especially noticeable at well edges (i.e. edge effect). Accordingly, there is a need for better in vitro models of primary human liver tissue that are more predictive of clinical outcomes and can be used with existing industrial automation for high-throughput screening in industry-standard multi-well formats (i.e. 96-well format).
The HepatoPac platform from Hepregen uses the predictive nature of human primary hepatocytes while extending the cultures stability and sensitivity by organizing hepatocytes into colonies of prescribed, optimized dimensions surrounded by supportive, non-parenchymal cells.
HepatoPac- A Bioengineered Micro-Liver Platform for Predictive Drug
Metabolism and Toxicity Studies
A Predictive, In Vitro Micro-Liver Co-culture System Providing In Vivo Performance
1. Assessment of a Micropatterned Hepatocyte Coculture System to Generate Major Human Excretory and Circulating Drug Metabolites. Wang, W. W. et al. Drug Metab Dispos. 38(10), p1900-1905 (2010). (title links to the page for this resource)
2. Microscale culture of human liver cells for drug development. Khetani, S.R. & Bhatia, S.N. Nat Biotechnol, 26(1), 120-126 (2007).
3. Primary hepatocytes: current understanding of the regulation of metabolic enzymes and transporter proteins, and pharmaceutical practice for the use of hepatocytes in metabolism, enzyme induction, transporter, clearance, and hepatotoxicity studies. Hewitt, N. J. et al. Drug Metab Rev. 39(1), p159-234 (2007).
4. Cellular imaging predictions of clinical drug?induced liver injury. Xu, J.J. et al. Toxicol Sci. 105(1), 97-105 (2008).
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