Reaching the Remote: Dried blood spot analysis for disease diagnosis on a protein microarray platform

Cancer remains one of the leading causes of death globally with an estimated 19.3 million cases and 10 million mortalities in 2020. In Africa and Asia, where remoteness is prevalent, access to healthcare facilities is limited, providing a significant barrier to effective screening and early detection of cancers in at-risk groups and thus, incomplete registries. Here, we utilised low resource, low-cost dried blood spots (DBS)-based sample collection coupled with robust, protein microarray technology to enable quantitative, multiplexed measurements of diagnostic autoantibody biomarkers of disease, in minimal sample volumes. Specifically, we describe the development of a DBS extraction and elution method from low cost, home-made blood cards. We then show that DBS stored at room temperature (25 {square}, RT) for up to 15 d yield comparable autoantibody signatures to autologous serum samples stored at -80 {square} and those from samples prepared on a commercially available blood card. We further conducted a pilot study, comparing total IgG and three previously identified autoantibodies upregulated in pancreatic cancer (PC), in DBS from 11 PC patients stored at RT for up to 15 d. We found comparable protein profiles across commercially developed blood cards and our low cost, in-house kit with no significant difference in autoantibody profiles over 15 d (p > 0.05). Such low cost, DBSbased sample collection methods, combined with regular, RT courier shipments and ultrasensitive protein microarraybased detection in a remote laboratory, thus have the potential to facilitate future, unbiased, large scale serosurveys and serological diagnostic testing within remote, rural communities.