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Chen CZ, Raghunath M. Focus on collagen: in vitro systems to study fibrogenesis and antifibrosis state of the art. FIBROGENESIS & TISSUE REPAIR 2009; 2:7. [PMID: 20003476 PMCID: PMC2805599 DOI: 10.1186/1755-1536-2-7] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Accepted: 12/15/2009] [Indexed: 02/06/2023]
Abstract
Fibrosis represents a major global disease burden, yet a potent antifibrotic compound is still not in sight. Part of the explanation for this situation is the difficulties that both academic laboratories and research and development departments in the pharmaceutical industry have been facing in re-enacting the fibrotic process in vitro for screening procedures prior to animal testing. Effective in vitro characterization of antifibrotic compounds has been hampered by cell culture settings that are lacking crucial cofactors or are not holistic representations of the biosynthetic and depositional pathway leading to the formation of an insoluble pericellular collagen matrix. In order to appreciate the task which in vitro screening of antifibrotics is up against, we will first review the fibrotic process by categorizing it into events that are upstream of collagen biosynthesis and the actual biosynthetic and depositional cascade of collagen I. We point out oversights such as the omission of vitamin C, a vital cofactor for the production of stable procollagen molecules, as well as the little known in vitro tardy procollagen processing by collagen C-proteinase/BMP-1, another reason for minimal collagen deposition in cell culture. We review current methods of cell culture and collagen quantitation vis-à-vis the high content options and requirements for normalization against cell number for meaningful data retrieval. Only when collagen has formed a fibrillar matrix that becomes cross-linked, invested with ligands, and can be remodelled and resorbed, the complete picture of fibrogenesis can be reflected in vitro. We show here how this can be achieved. A well thought-out in vitro fibrogenesis system represents the missing link between brute force chemical library screens and rational animal experimentation, thus providing both cost-effectiveness and streamlined procedures towards the development of better antifibrotic drugs.
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Affiliation(s)
- Clarice Zc Chen
- Division of Bioengineering, Faculty of Engineering, National University of Singapore, DSO Building (Kent Ridge), Medical Drive, Singapore
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Dash A, Inman W, Hoffmaster K, Sevidal S, Kelly J, Obach RS, Griffith LG, Tannenbaum SR. Liver tissue engineering in the evaluation of drug safety. Expert Opin Drug Metab Toxicol 2009; 5:1159-74. [PMID: 19637986 PMCID: PMC4110978 DOI: 10.1517/17425250903160664] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Assessment of drug-liver interactions is an integral part of predicting the safety profile of new drugs. Existing model systems range from in vitro cell culture models to FDA-mandated animal tests. Data from these models often fail, however, to predict human liver toxicity, resulting in costly failures of clinical trials. In vitro screens based on cultured hepatocytes are now commonly used in early stages of development, but many toxic responses in vivo seem to be mediated by a complex interplay among several different cell types. We discuss some of the evolving trends in liver cell culture systems applied to drug safety assessment and describe an experimental model that captures complex liver physiology through incorporation of heterotypic cell-cell interactions, 3D architecture and perfused flow. We demonstrate how heterotypic interactions in this system can be manipulated to recreate an inflammatory environment and apply the model to test compounds that potentially exhibit idiosyncratic drug toxicity. Finally, we provide a perspective on how the range of existing and emerging in vitro liver culture approaches, from simple to complex, might serve needs across the range of stages in drug discovery and development, including applications in molecular therapeutics.
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Affiliation(s)
- Ajit Dash
- Underwood-Prescott Professor of Toxicology and Chemistry, Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Office 56-731A, Cambridge, MA 02139, USA
| | - Walker Inman
- Underwood-Prescott Professor of Toxicology and Chemistry, Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Office 56-731A, Cambridge, MA 02139, USA
| | - Keith Hoffmaster
- Novartis Institute of Biomedical Research, 350 Massachusetts Avenue, Cambridge, Massachusetts, MA 02139, USA
| | - Samantha Sevidal
- Pfizer Research Technology Center, Cambridge, Massachusetts, MA 02139, USA
| | - Joan Kelly
- Pfizer Research Technology Center, Cambridge, Massachusetts, MA 02139, USA
| | - R Scott Obach
- Pfizer Research Technology Center, Cambridge, Massachusetts, MA 02139, USA
| | - Linda G Griffith
- Underwood-Prescott Professor of Toxicology and Chemistry, Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Office 56-731A, Cambridge, MA 02139, USA
| | - Steven R Tannenbaum
- Underwood-Prescott Professor of Toxicology and Chemistry, Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Office 56-731A, Cambridge, MA 02139, USA
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