Evaluation of genomic DNA stability and white blood cell integrity in TFLB and Streck blood collection tubes for oncology diagnostics application.

Abstract

e22563 Background: Reliable stabilization of genomic DNA (gDNA) and cellular integrity is critical for oncology clinical trials and molecular diagnostics, specifically for germline mutations. The stability of gDNA is required to extend transport times. TFLB is a single-tube solution designed to stabilize intact cells, nucleic acids, and proteins for five days or more. This study aimed to characterize the long-term stability and extractability of gDNA and the white blood cell (WBC) integrity characterization via flow cytometry from buffy coat samples stored in TFLB compared to Streck Nucleic Acid (NA) and Streck cfDNA tubes at ambient temperature. Methods: Whole blood was collected into TFLB, Streck Nucleic Acid (NA), and Streck cfDNA tubes and stored at 22°C. gDNA was extracted from buffy coat fractions at Days 1, 3, 5, and 7. In a parallel evaluation, WBC stability is being assessed via flow cytometry for 24-hour intervals up to 96 hours (T0–T4). Flow parameters include Forward/Side Scatter for cell morphology and CD45+ gating to monitor apoptosis and membrane integrity. Results: TFLB demonstrated high and consistent gDNA recovery through the first 72 hours (~60 ng/µl), followed by a significant increase in extractable concentration to ~110 ng/µl by Day 7. In contrast, both Streck NA and Streck cfDNA tubes exhibited a catastrophic decline in extractable gDNA after Day 3. Yields for Streck NA dropped from ~54 ng/µl at Day 3 to ~4 ng/µl at Day 5, while Streck cfDNA yields fell from ~36 ng/µl to ~4 ng/µl in the same period. Streck BCT variants maintained near-zero extractable gDNA levels through Day 7. Flow cytometry analysis determined that the gDNA correlates with the stabilization of WBCs in TFLB for up to 96 hours. Streck’s loss of gDNA concentration correlates with aggressive cell fixation or early-stage apoptosis in Streck tubes. Conclusions: TFLB effectively maintains gDNA extractability from buffy coat for up to 7 days at ambient temperature, whereas Streck tubes showed a loss of extractable DNA after 72 hours. The sharp decline in Streck tubes likely reflects aggressive cell fixation or DNA cross-linking rather than DNA degradation, making them unsuitable for delayed gDNA extraction from cellular fractions using standard protocols. The integration of flow cytometry further defines how these tubes preserve cellular surface markers and viability. These findings suggest that TFLB provides a more robust platform for clinical trials requiring integrated cellular and molecular analysis from a single blood draw.