A new methodology to preserve the original proportion and integrity of cell-free fetal DNA in maternal plasma during sample processing and storage.

Objective: To develop a standardized blood collection device that preserves fetal cell-free DNA and minimizes the cell-free DNA background in maternal plasma.

Methods: Blood samples were drawn from healthy pregnant donors into K(3)EDTA (BD vacutainer) and Cell-free DNA BCT tubes (Streck, Inc.) and kept at ambient temperature. Plasma was separated by centrifugation and cell-free DNA was extracted. Cell-free DNA from plasma was quantified by quantitative real-time polymerase chain reaction.

Results: Blood drawn into Cell-free DNA BCT tubes showed no change in the original proportion of fetal cell-free DNA during a 14-day storage period at ambient temperature. Conversely, maternal blood drawn into K(3)EDTA tubes showed a steady reduction in the original proportion of fetal cell-free DNA over the same time period. Using maternal plasma stored in Cell-free DNA BCT tubes for 14 days, fetal cell-free DNA was amplified 80-fold using whole genome amplification (WGA).

Conclusion: Using Streck's Cell-free DNA BCT tubes, it is possible to preserve the original proportion of fetal cell-free DNA for extended times as well as minimize the post-sampling maternal cell-free DNA background. Preserved in this way, fetal cell-free DNA can be amplified by WGA technology to be used in prenatal diagnostic tests.