Transport under various conditions: Evaluating blood sample stability across seasons

INTRODUCTION: For analysis of circulating cell-free DNA (ccfDNA) in cancer screening or monitoring, specialized blood collection tubes - such as the PAXgene ® Blood ccfDNA Tube (PreAnalytiX) - offer a reliable solution for users who are unable to process samples within 4 hours of collection. These tubes stabilize ccfDNA profiles by preventing blood cells from releasing genomic DNA (gDNA) during transport, thereby preserving sample integrity for sensitive downstream ccfDNA analyses. According to international standards and regulations (ISO 20186-3:2019, (EU) 2017/746 on In Vitro Diagnostic Medical Devices) preanalytical conditions like sample collection, transport, and storage must be validated to ensure that the quality of ccfDNA is maintained. Here, we evaluated sample packaging, temperature fluctuations during transit, and the impact of shipment on downstream assay performance to assess whether blood samples in PAXgene tubes can be transported at ambient temperature. METHODS: Blood was collected from 30 apparently healthy consented donors into PAXgene Blood ccfDNA Tubes. Filled tubes were processed within 4 hours after phlebotomy or stored refrigerated (2-8°C), at 15°C or at room temperature (15-25°C) for 10 days and at 30°C for 7 days. For international transport tubes were shipped from the collection site (QIAGEN, Hilden, Germany) to an external processing site (BD, Franklin Lakes, USA). Samples were placed in insulated boxes compliant with IATA standards and without active temperature control. This included a leakproof triple packaging concept with a primary receptacle, a secondary package, and a rigid outer package. Upon arrival, blood samples were processed directly or subjected to an additional transport simulation test according to requirements defined in the standard ASTM D4169. Plasma and cellular fraction were separated, frozen and shipped back to QIAGEN for ccfDNA and gDNA extraction and analysis. RESULTS: Temperature fluctuations during transport were in the range of 18-35°C during summer and 7-25°C during winter. Additional drop, vibration and altitude tests to simulate transportation by truck, rail and air did not compromise yield or quality of DNA. The relative yield of ccfDNA from plasma, measured by qPCR, between samples processed immediately and after storage or transport and simulation was only slightly increased with mean values between 1.0- to 1.3-fold. gDNA yield and purity measured by spectrophotometry were high for all conditions in the range of 26 to 55 µg of gDNA per mL of cellular fraction and mean 260/280 ratios between 1.80 and 1.82. CONCLUSION: Excellent sample stability could be demonstrated in whole blood samples collected into PAXgene Blood ccfDNA Tubes under both controlled storage and real-world transport conditions. The data confirm that sample integrity is maintained following air and ground transportation at ambient temperatures across both summer and winter seasons.