BACKGROUND:
Fluid biomarkers are useful tools in disease detection, monitoring, and treatment. However, current sampling methodologies are invasive and timely procedures that require patients to travel to clinics, trained staff, and resources costly to the healthcare system. The use of micro-sampling offers a solution: it requires only a finger-prick blood sample which can be performed at home and mailed to a lab for analysis. However, thorough validation of micro-samples for biomarker detection and assessment of the feasibility of at-home sampling are needed.
METHODS:
Quanterix’s Single Molecule Array (SIMOA) platform was used to compare pTau-217, NfL, and GFAP concentrations in Capitainer SEP-10 DPS made from venous (DPS ven) blood against matched plasma. Each Capitainer SEP-10 card uses ~70uL of whole blood and performs on-board plasma separation to produce two 10uL DPS ven. Different storage conditions and extraction protocols involving the use of one (1x DPS ven) or two (2x DPS ven) DPS were assessed.
RESULTS:
Concentrations of pTau-217, GFAP and NfL were detectable in 1x DPS ven stored at RT. Concentration of pTau-217 and GFAP correlated to concentrations measured in matched plasma (R 2 = 0.82 from 2x DPS ven and 0.78 from1x DPS ven), respectively), but not NfL (R 2 = 0.37 from 1x DPS ven). Concentrations of pTau-217, were detectable in DPS ven stored at room temperature (RT) for up to 6 weeks. Storage at -70°C saw no significant difference in DPS ven pTau-217 concentration compared to RT (p = 0.73, from 2x DPS ven).
CONCLUSION:
These results display that DPS can be used to detect pTau-217, NfL and GFAP in plasma, and suggests that DPS have potential to be used as a screening tool for some neurodegenerative diseases. However, further validation is required for different biomarkers, immunoassays, and card types, as well as assessing the feasbility and challenges of at-home sampling.