“I think [the RainDance technology] holds lots of promise in a clinical setting,” says Hegde, who has been working with the technology for the last two years. But she also notes its cost. “The machine is very expensive,” she says, in the range of $200,000 to $250,000.
RainDance’s microdroplet technology is just one of a number of methods under development for selecting relevant genes within the genome. The Emory lab, for example, is also working with a technology from Fluidigm, another microfluidics company. It remains to be seen which will prove most effective in different situations.
One market that RainDance aims to dominate is cancer diagnostics, such as analyzing tumors for specific mutations that make them more likely to respond to certain drugs. Analyzing cancer DNA presents a unique challenge; the technology must be able to detect mutations in the tumor, which may occur in only a small subset of cells. Typical amplification methods expand both normal and cancerous pieces of DNA together, meaning the cancer mutation can get lost. One advantage of RainDance’s droplet technology is that it amplifies only one piece of DNA per droplet.
Foundation Medicine’s Borisy says the company will likely explore RainDance’s technology when developing its cancer genetic test. However, he cautions that cancer diagnostics need to be able to accurately amplify DNA from a very small sample. “For routine oncology, you need to be able to work from 100 nanograms or less,” he says.
RainDance is also working on a number of other applications, such as analysis of single cells, which could be used for drug toxicity testing. For example, drug companies could encapsulate single cells into droplets, expose the cells to experimental compounds, and then add fluorescent tags designed to bind to markers of cell death.