Trophoblast retrieval and isolation from the cervix for noninvasive prenatal screening at 5 to 20 weeks of gestation

Capsule:
Fetal cells retrieved by endocervical cytobrush at 5–20 weeks of pregnancy and isolated with immunomagnetic nanoparticles are extravillous trophoblast cells that contain intact fetal DNA useful for prenatal testing.

Authors:
Jay M. Bolnick, M.D., Brian A. Kilburn, B.S., Swati Bajpayee, B.S., Nitya Reddy, B.S., Roohi Jeelani, M.D., Barbara Crone, R.N., Neil Simmerman, M.D., Manvinder Singh, M.D., Michael P. Diamond, M.D., D. Randall Armant, Ph.D.

Volume 102, Issue 1, Pages 135–142.e6

Abstract:

Objective:
To use trophoblast cells accumulating in the endocervical canal at the beginning of pregnancy for noninvasive prenatal testing.

Design:
Prospective, double-blinded test for fetal gender.

Setting:
Academic medical center.

Patient(s):
Fifty-six women with singleton pregnancies at gestational age 5–20 weeks.

Intervention(s):
Isolation of fetal cells from resident maternal cells in endocervical specimens using anti-human leukocyte antigen G coupled to magnetic nanoparticles; cell phenotyping immunofluorescently with a panel of trophoblast subtype-specific proteins; DNA integrity assessment with terminal dUTP nick-end labeling (TUNEL); and polymerase chain reaction (PCR) and fluorescent in situ hybridization (FISH) to detect sex chromosomes in individual cells.

Main Outcome Measure(s):
Trophoblast phenotype, TUNEL index, and percentage male cells.

Result(s):
The women were given a routine Papanicolaou test; fetal genders were verified from medical records. Recovery after immunomagnetic isolation averaged 746 ± 59 cells across gestational age, with 99% expressing chorionic gonadotropin, whereas the depleted cell fraction expressed none. The isolated cells had an extravillous trophoblast phenotype and intact nuclear DNA (>95%). Fetal gender was determined in 20 specimens without error by PCR. The FISH analysis of isolated cells from male specimens validated their fetal origin.

Conclusion(s)
Noninvasive prenatal testing is feasible beginning at a gestational age of 5 weeks.

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