Cellscape Hunts for Fetal Cells in Mom, Pushing Diagnostic Frontier
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with about 16-17 milliliters of blood from the mom, which has about 100 billion cells of all different types, Drexler says. The company runs a physical process to filter out the red blood cells, separating the ones that don’t have a nucleus, leaving about 1 billion cells.
Other companies at this point have used chemical or magnetic processes to separate out cells of interest, which have been too harsh for fetal cells, Drexler says. So Cellscape uses what it calls “optical enrichment” which uses a stain to highlight the nucleus under fluorescent lighting, in a high-resolution manner. This method is gentler, and allows the company to whittle down the sample down from 1 billion cells to about 1,000 cells for analysis, Drexler says.
And that’s not the end. The fetal cells still need to be identified as distinct from the mother’s. Cellscape does that by looking for a protein that is more heavily expressed in maternal cells, which it says is a core part of its intellectual property. Once they are sure they have “tens to hundreds” of cells from the fetus, and not the mom, then they go through the final steps. The DNA gets taken out for amplification through standard PCR methods, and the amplified DNA from the fetal cells is hybridized on a chromosomal microarray. The results are analyzed on an array scanner from Agilent Technologies. [Correction 3:15 pm PT: An earlier version said gene expression patterns are analyzed.]
By looking at certain targeted regions of the fetus’s genome, Cellscape believes this method will be able to detect not only the chromosomal abnormalities that today’s DNA-based methods spot, but also another 20-30 “microdeletion” syndromes in which a small stretch of DNA is missing or defective, Drexler says. (DiGeorge Syndrome is one example). Results from the sample should take about one week to send back to the doctor, Drexler says.
Cellscape has spent the past few years trying to nail down this process. It has run some blood samples through its system, but hasn’t yet published the big kind of controlled clinical trial in a medical journal that would show its test is ready for prime time.
The stakes are about as high as it gets in medicine, as people make life-altering decisions based on prenatal diagnostic information. “We want to be 100 percent sure that the cells we say are fetal are actually fetal,” Snelgrove says. Not only that, but you can be sure that physicians are going to want to double-check the results they get from a Cellscape analysis with another analysis that comes from a traditional invasive procedure, like CVS or amniocentesis, where there’s no doubt about what kind of cells you’re analyzing. “It’s important to have a way to confirm the result,” Drexler says.
Cellscape doesn’t have traditional venture capital backing, but its investor group does include RA Capital, a Boston-based hedge fund. The company, still in R&D mode, has grown to 36 employees.
The next phase of growth for Cellscape is about gathering convincing data. The clinical trials that it develops to test its process will go a long way toward determining what kind of price it can command, and whether it can persuade insurers to pay for its product. If things move fast, Cellscape could hit the market by late 2014, but it is likely shooting for early 2015, Snelgrove says.
The day will come when Cellscape will want to tout its offering, but it’s not ready yet. There’s still a lot of work to do.