Michael Schirm

Senior scientist, Protein chemistry, Caprion Proteomics, Montreal

Challenges of Plasma Proteomic Biomarker Discovery

New biomarkers are urgently needed to improve the diagnosis of diseases. The preferred diagnostic sample for biomarker discovery is human blood. It is easily accessible and, along with the common plasma proteins, it contains secreted proteins from all organs and tissues of the human body. Therefore, it may potentially allow the detection of any disease or disease state. However, discovery of biomarkers in plasma is very challenging. Plasma protein concentrations span a wide dynamic range >10 orders of magnitude with the top 10 most abundant proteins accounting for around 90% of the total plasma proteins. This makes the detection of low abundant proteins difficult.

We have developed highly multiplexed multiple reaction monitoring (MRM) assays allowing the accurate and precise quantification of hundreds of low and medium abundance plasma proteins within a single 30 min run. The lower limit of detection (LLOD) of these assays is in the low ng/mL range. The development of these MRM assays has been automated, with development for around 5,000 peptides within a week. These MRM assays were then applied to identify potential biomarkers for several diseases such as lung cancer.