Abstract

Applying Phage-Displayed Random Peptide Libraries to Identify Exosomes as Biomarkers in Patients with Central Nervous System Disorders

Xiaoli Yu, Assistant Professor, University of Colorado Anschutz Medical Campus

Like most other cells, brain tumor cells shed extracellular vesicles (EV) into their external environment and are considered potentially high-value biomarker reservoirs. We hypothesize that phage-displayed random peptide libraries can be applied to identify EV of CNS origin, and high affinity phage peptides can be used for rapid isolation and characterization of extracellular vesicles from blood of patients with brain tumors. Phage display has been successfully applied to many different areas of research, including immunology, cancer, drug discovery, epitope mapping, protein-protein interactions, and infectious diseases, targeting a broad cross section of protein families. Phage display technology is based on the construction of a polypeptide library fused to a bacteriophage coat protein. Phage are screened (“panned”) on surfaces coated with potential targets. We have applied two Phage-display peptide libraries (7mer &12 mer) and identified high affinity peptides specific to exosomes derived from brain tumor cell-lines and plasma of patients with other CNS disorders. The peptides shared high sequence homologies within the ones selected by the same panning targets as well as with others panned by exosomes from different sources. Our data suggest that phage peptide technologies can be used for enrichment, isolation, and characterization of EVs derived from different CNS cell types from blood of brain tumor patients and other CNS disorders.