A novel approach to stabilize fetal cell-free DNA fraction in maternal blood samples for extended period of time.

This study was undertaken to evaluate a novel method for stabilizing and preserving the original proportion of cell-free fetal DNA (cffDNA) in maternal blood for extended periods of time without using crosslinking agents, such as formaldehyde, which compromise DNA integrity and extraction efficiency. Blood was drawn from pregnant donors into K3EDTA and Blood Exo DNA ProTeck® (ProTeck) tubes. Blood drawn into both tubes were aliquoted and stored at three different temperatures.

Analysis of human blood plasma cell-free DNA fragment size distribution using EvaGreen chemistry based droplet digital PCR assays.

Background: Plasma cell-free DNA (cfDNA) fragment size distribution provides important information required for diagnostic assay development. We have developed and optimized droplet digital PCR (ddPCR) assays that quantify short and long DNA fragments. These assays were used to analyze plasma cfDNA fragment size distribution in human blood.

New evidence that a large proportion of human blood plasma cell-free DNA is localized in exosomes.

Cell-free DNA (cfDNA) in blood is used as a source of genetic material for noninvasive prenatal and cancer diagnostic assays in clinical practice. Recently we have started a project for new biomarker discovery with a view to developing new noninvasive diagnostic assays. While reviewing literature, it was found that exosomes may be a rich source of biomarkers, because exosomes play an important role in human health and disease.

Stabilization of white blood cells and immunologic markers for extended analysis using flow cytometry.

We evaluated whole blood samples drawn from 25 healthy donors and 20 HIV-infected donors into K3EDTA and Cyto-Chex BCT blood collection tubes for CD4, CD8, and CD3 cell counts (HIV Panel). Samples collected in Cyto-Chex BCT were stored at room temperature and tested by 4-color flow cytometry at 6 h, 3 days, and 7 days after isolation for CD4, CD8, and CD3 absolute cell counts/microl and compared with samples collected in K3EDTA tubes and tested at 6 h. Regardless of donor type, the samples collected in Cyto-Chex BCT and tested on day 7 yielded results that were statistically indistinguishable (with correlation coefficients of 0.