UK-based Gentronix has successfully co-cultured its GreenScreen HC genotoxicity reporter cells with fresh hepatocytes preserved in Abcellute’s matrix in the presence of test material, Abcellute said this week.
These findings, which Gentronix presented at the recent Society of Toxicology meeting in Seattle, are noteworthy because they bring the use of fresh hepatocytes to test drug metabolites one step closer to becoming the methodology of choice for screening drug candidates for hepatotoxicity. S9 liver enzyme extracts, which are currently used to test drug candidates, have limited metabolic activity.
“As proof of principle, we showed that the combination of GreenScreen HC and Abcellute’s cells generates expected results from a small handful of positive and negative compounds — including those where we know the liver does not make a difference. We are now going to widen the study to a larger group of compounds,” said Richard Walmsley, founder, scientific director, and CSO of Gentronix.
Gentronix will now look at different classes of metabolism, Walmsley told CBA News this week. “The data presented at the Society of Toxicology meeting concentrated on just a few phase I, cytochrome p450 enzymes. There are probably four or five p450s responsible for most potentially “bad” metabolic processing, so we are going to look for more representative, drug-like molecules that are metabolized by these various p450s,” Walmsley said.
He added that Gentronix now also needs to look at chemicals that should be metabolized by other, phase II enzymes in Abcellute’s preserved hepatocytes, to make sure all of the relevant activities are present in the cells.
“Then we shall seek some biotech or pharma company who would like to collaborate on perhaps a more meaningful study, where we look at compounds from their library,” said Walmsley. He added that it is too early to have identified a partner.
Abcellute’s method for preserving hepatocytes without freezing them will not alter the cells’ integrity, which is what freezing would do, according to the company. “The technology ... effectively means that cells can be used successfully over five days from preservation.” In addition, because the cells are not frozen, the potential for damage from ice crystals is eliminated.
“We are now going to widen the study to a larger group of compounds.”
Preservation is achieved by immersing the cells in a matrix that coats and protects the cells, the company said. The metabolic function of the cells is preserved, and they remain in their native state. Prior to use, the cells are re-activated and subsequently behave as normal fresh cells, retaining their “intact whole organ” characteristics.
Cells can be shipped at ambient temperatures of between 10° C and 11° C, which means that they can be shipped over long distances.
Walmsley said that he first became interested in Abcellute’s technology when he met Abcellute founder Nathan Griffiths at a scientific meeting in the UK several years ago.
“After I met [Griffiths], and heard about his method for preserving hepatocytes, we got a small grant between us, to investigate whether our cells and his cells were compatible, and whether we could set up an assay,” said Walmsley.
He went on to say that the Gentronix and Abcellute teams found they could add Gentronix’s engineered GreenScreen cells in with Abcellute’s hepatocytes, add drugs known to be metabolized in and toxic to the liver, and Gentronix’s cells would turn green, “as they should when they see genotoxins.”
Abcellute did not respond to a request for comment by press time.
Gentronix has just submitted two papers for publication demonstrating that the Green Screen HC assay can be used with S9 extracts, “and our next submissions may be about this hepatocyte work,” Walmsley said.
“During the last year we have switched about 90 percent of our GreenScreen GC customers to the GreenScreen HC human cell assay,” he said.
Walmsley said that now that Gentronix has better developed the GreenScreen HC with Metabolic Activation [that uses S9 liver extract] protocol to evaluate the genotoxicity of drug metabolites, the company is just starting a transferability exercise with what he would only describe as a “very well-known, top 3 pharma,” to make sure that the protocol works in other labs.
Since Gentronix launched the HC assay last year, a paper was published in Mutation Research/Genetic Toxicology and Environmental Mutagenesis that tested 16 compounds in an inter-laboratory study, and found that the protocol could be successfully used in different labs. Participants in the study included Unilever, Johnson & Johnson, GlaxoSmithKline, and the UK’s University of Manchester and the University of Wales Swansea.
This year, Gentronix launched GreenScreen HC with Metabolic Activation, (see CBA News, 3/14/08). Walmsley declined to name exact sales figures for the GreenScreen HC assay.
In addition to marketing its GreenScreen assay kits, Gentronix does some service testing. “People were so keen to have the metabolism readout, that once we got the HC developed, we started offering that as a service here, before we refined the protocol sufficiently to send out to other people to use themselves,” said Walmsley. The Metabolic Activation S9 version of the HC has been available through Gentronix, and soon will be available through CROs as well, he said.
BioReliance offers the GreenScreen HC assay in the US, and the company has just trained Covance to sell the product in the UK market, said Walmsley.
In an e-mail to CBA News, Susan Riley, a senior business development manager at Covance, said, “We have been aware of Gentronix and GreenScreen for several years, through discussions with Gentronix scientists at meetings, attendance at their scientific presentations, and through their publications.”
Covance is starting to work with the Gentronix GreenScreen HC system to offer it as part of its screening package for candidate selection and lead optimization. “The GreenScreen HC system … has the advantage of speed, specificity, and a low test chemical requirement,” said Riley.
Since last year, Gentronix has also hired a new commercial director, Steven Beasley, and a full-time sales manager, Paul Docherty.