Proteomic Profiling Using a Proximity Extension Assay Panel on Serum Samples Stored at −25°C Over Several Decades

The advent of proteomics assays that provide accurate levels of thousands of proteins from relatively small sample volumes opens possibilities for biomarker research in biobanks with valuable samples. In this study, we leverage the applicability of the Olink proximity extension assay to profile serum samples of the Janus Serum Bank, which have been stored at –25°C for several decades. We perform association analysis for the body mass index, sex, smoking status and storage time, and compare these associations against protein associations of these traits in the UK Biobank. We identify significant and plausible associations of proteins levels for the analysed phenotypes. Furthermore, these associations showed a high degree of correlation to the analyses performed on the large‐scale studies by the UK Biobank. The samples obtained in the UK Biobank were collected according to modern standards, with short processing time for the blood samples, and storage at very low temperatures, whereas samples in the Janus Serum Bank were collected over larger timespans, with storage in sub‐optimal temperature and over prolonged periods of time as compared to todays’ standards. This research shows that samples stored under sub‐optimal conditions and over extreme periods of time (up to 50 years) yield reliable protein associations for common traits using a proximity extension assay. Therefore, archived biosamples that were not stored in optimal conditions, including samples of the Janus Serum Bank, remain a highly valuable resource in disease and risk biomarker research using modern and emerging proteomics assay methods.