Over the past six years, researchers at Trinity College Dublin have been exploring the intersection of nanofluidics and cell biology in an attempt to create a new type of assay that mimics the natural environment of cells: the extensive network of capillaries found in the human body.
Those researchers now believe they have developed the technology to the point where it can market it early next year through startup biotechnology company Cellix.
The technology, a biochip tentatively called Structor, is a transparent, plastic, microfluidics chip that has up to eight separate channels, each of which is around 200 microns wide, 20 microns deep, and 20 millimeters long, and holds fluid volumes ranging from one to 15 microliters. It is to be coupled with Mirus, the firm’s microfluidics pumping system, which can adjust the increment, composition, and flow rate with which assay materials are pumped into the chip.
Cellix was spun out of a collaboration between Trinity’s nanofluidics group, within the department of physics, and the cell signaling group that is part of the college’s department of clinical medicine. The head of the nanofluidics group is Igor Shvets, who is also one of Cellix’ directors, while the cell signaling team is fronted by Dermot Kelleher.
In a typical assay, Structor’s microcapillaries may be coated with antibodies, or specific cells of interest, the firm said. Researchers would inject cell suspensions into the chip and analyze the cells’ reactions under continuous flow conditions to the antibody- or cell-coated microcapillary walls.
Last week, Shvets, Kelleher, and the other scientists involved in developing the technology received US patent number 6,770,434, the latest of several US and European patents that have been issued to the group recently. To be sure, though the title of the patent — “Biological assay method” — may be broad, the sales and business development manager for Cellix last week told Inside Bioassays that the primary manifestation of the intellectual property is a microfluidics-based biochip and accompanying nanopump system designed to change the way cell-based assays are performed.
“For many years now, cell-based assays have been performed in isolation in a well plate setting, [which] … has many limitations with respect to mimicking an in vivo environment,” according to Chief Technology Officer Siobhan Mitchell. “Given that cells are in constant communication with each other and with their local microenvironment through a multitude of interactions, it is important to strive to reproduce this setting as closely as possible to yield more informative results.
“Analyzing cells under flow replicates the body’s exquisite transport network, where key sensing activity alerts the body to invading pathogens, changes in blood gas composition, and toxic compound presence,” Mitchell added. “Also, examination of cells under flow allows [a] detailed dissection of disease processes where controlled cell migration from the blood stream to sites of infection and injury is paramount to mounting an efficient immune response.”
Asthma is a good example of a disease state in which cell migration — or, rather, inappropriate cell migration. Mitchell said beta-testers at an undisclosed Scottish institution are currently using Cellix’ system to evaluate new modulators for these kinds of cellular behaviors.
Cellix has also developed accompanying software for the nanopump, called FlowAssay, and for cellular analysis, known as CellProfiler. The CellProfiler allows researchers to quantify and analyze changes in cell adhesion and shape, and can be used in with images that are recorded with currently available image acquisition programs.
As far as readout instrumentation goes, Mitchell said that “all you need is a microscope and a camera that allows magnified analysis of what is happening in the channels,” but that the biochips are compatible with many fluorescent plate readers, “allowing researchers to read absorbance [or] fluorescence along the length of the channels.”
“This is particularly useful to quantify exact receptor expression or activity status using GFP or alternatively labeled molecules in the cell, or to examine basic cell adhesion to alternate matrices [or] inflammatory ligands,” Mitchell added.
Cellix is currently not partnered with an instrumentation company, Mitchell said, adding that “if … an instrumentation company would like to work with us, we would be delighted to cooperate.”
For the past two years, Cellix has been funded by Enterprise Ireland, a Dublin-based government agency that helps nurture Irish industry. In addition, Mitchell said Cellix is currently in discussions with potential private investors. Whether under current funding or with the help of private equity, Cellix is ready to go forward with the product in early 2005 in its current form, Mitchell said, as the company has initiated a “design freeze” on the platform.
“Initially, we intended to target the academic market, primarily research laboratories working in … cancer and inflammation … [which would allow] us to gain validation of the product for the pharmaceutical market,” Mitchell said. “With respect to the pharmaceutical market, this technology will be utilized to enhance low throughput high content screening of lead compounds.”
Recently, she added, a number of pharmas have approached Cellix with the idea of implementing continuous flow assays into their drug discovery. “As … researchers in the academic and pharmaceutical industry are embracing the product, we now intend to target both markets simultaneously,” she said.
Continuous flow assays are a relatively new area in high-content screening, falling somewhere between flow cytometry and standard microtiter plate-based assays. Cellix has some competition in this area, most notably Caliper Life Sciences, the publicly traded, Hopkinton, Mass.-based company whose LabChip platform for cell-based assays uses sipper chips developed in-house to perform numerous continuous flow assays in parallel.
Other companies making a splash in this area include Guava Technologies, of Hayward, Calif., with its Personal Cell Analysis system, and fledgling Swedish biotech firm Cellectricon, whose DynaFlow platform has been available in Europe since October and is currently being introduced in the US.
Besides the unidentified Scottish institution, Mitchell said Cellix has beta-testers for its product at the US National Cancer Institute. The company is still looking for its first big pharma or biotech partner, and it eventually plans to upgrade the platform from eight assay channels to make it more attractive.
“We decided to start with a simple design that is easy to use,” Mitchell said. “However, we have had requests to increase the number of capillaries in a single biochip. This is definitely possible, and future biochip modules will have greater numbers of capillaries, and hence, higher throughput.”