Investigational Prenatal Test Uses Endocervical Mucus


COPENHAGEN — An investigational prenatal diagnostic test that uses fetal cells taken from maternal endocervical mucus could offer all the advantages of chorionic villus sampling, according to a study sponsored by Biocept Inc., the San Diego company that's developing the test.

“This is a completely noninvasive diagnostic test that you can do in the first trimester. It's not just a screening test, which is what the other noninvasive tests are,” said study investigator Farideh Bischoff, Ph.D., of Baylor College of Medicine in Houston.

The idea of analyzing trophoblast cells taken from maternal blood or cervical mucus has been pursued for some time. However, inefficient endocervical sampling procedures and the scarcity of trophoblasts in maternal blood have hampered attempts to develop a reliable prenatal test.

The Biocept test involves collecting maternal endocervical mucus with a brush similar to that used to collect samples for Pap smears. A cell capture device is used to isolate fetal trophoblasts from the mucus. Next, an antibody-based purification system filters out the maternal cells.

In a study she presented at the annual meeting of the European Society of Human Reproduction and Embryology, Dr. Bischoff described immunohistochemical staining and fluorescence in situ hybridization testing on purified cells from 100 women.

The initial endocervical mucus sample contains very small numbers of trophoblasts and following the purification technique can strengthen the concentration to a purity of 85%–95%.

Diagnostic testing of the remaining trophoblast cells is then possible to detect chromosomal aneuploidies, she said.

“If you run a panel of probes you can detect trisomies. Alternatively, you can do DNA testing on the cells to screen for mutations. It basically allows you to do the same tests that investigators are doing with preimplantation embryos,” she said.

Dr. Bischoff said Biocept is running a clinical evaluation study at centers nationwide to compare the results of the test with those of standard chorionic villus sampling in a group of pregnant women.

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