The effect of the elapsed time between blood draw and processing on the recovery of fetal cells from maternal blood.
OBJECTIVE
To test the hypothesis that a delay in initial fetal cell enrichment processing of maternal blood samples (defined as the time between blood draw and the initial density gradient centrifugation step) compromises the ability to recover fetal cells, we performed a randomized comparison of immediate (within 4 hours of draw) versus delayed (between 18-24 hours of draw) processing.


METHODS
Four centers participated: two centers utilized flow cytometry (FLOW), and two centers utilized magnetic-activated cell sorting (MACS) techniques. Each center collected 34 samples. The outcome was the percentage of gamma positive (gamma(+)) cells for FLOW or the number of nucleated red blood cells (NRBCs) for MACS, found in the final enriched cell population. Both outcomes reflect cell properties that are potentially fetal in origin, thus making them representative of the ability to recover fetal cells.


RESULTS
Our results did not support our hypothesis that delay in processing compromises fetal cell recovery. Instead, in MACS processing, we observed an increase in recovered NRBCs when blood sample processing was delayed compared with immediate processing. There was no significant difference in gamma(+) cells with FLOW.


CONCLUSIONS
Time-related changes in the density of target cells, perhaps associated with their progress towards apoptosis during the delay period, may result in increased intact fetal cells with the study methods utilized.
Dukes
K A
KA
DM-STAT Inc., Medford, Massachusetts 02155, USA. Kim.Dukes@dmstat.com
Sullivan
L M
LM
Lewis
D
D
Johnson
K L
KL
Bianchi
D W
DW
Simpson
J L
JL
Holzgreve
W
W
Hahn
S
S
Bischoff
F Z
FZ
Jackson
L G
LG
D017209:Apoptosis; D001800:Blood Specimen Collection / Q000379:methods*; D002452:Cell Count; D002469:Cell Separation / Q000379:methods; D002499:Centrifugation, Density Gradient; D004900:Erythroblasts; D005260:Female; D005312:Fetal Blood / Q000166:cytology*; D005434:Flow Cytometry; D006801:Humans; D008280:Magnetics; D011247:Pregnancy; D013997:Time Factors