Advances in Proteomic Sample Preparation Strategies for Human Disease Biomarker Discovery

Proteomic techniques are widely used as strategies to identify pathological changes that can be reflected in plasma/serum protein levels. These techniques are employed in searching for new clinical biomarkers that may be useful in diagnosis, prognosis, assessment of disease progression, and treatments for a specific condition. Several research groups are dedicated to screening and identifying potential biomarkers for various conditions such as cancer, viruses, neurodegenerative diseases, diabetes, among others. Typically, biomarkers are low-abundance proteins, which are presented in complex matrixes and can be masked by high-abundance proteins (such as albumin, transferrin, apolipoprotein and immunoglobulins), representing a challenge for proteomic studies. Approaches involving sample fractionation, depletion of high-abundance proteins, and enrichment of low-abundance proteins are employed to reduce sample complexity, increase analytical sensitivity and accurately identify and quantify the target molecules, overcoming some of the limitations of the proteomic analyses. In this review, we proposed an in-depth discussion of the more important and moderns proteomic sample preparation strategies, as well as their practical application in the search for specific biomarkers in biological samples.