Single-extracellular vesicle (EV) analyses validate the use of L1 Cell Adhesion Molecule (L1CAM) as a reliable biomarker of neuron-derived EVs

However, full methodological validation requires demonstration of L1CAM in individual NDEVs and lower levels or absence of L1CAM in individual EVs from other cells. Here, we used multiple single-EV techniques to establish the neuronal origin and determine the abundance of L1CAM-positive EVs in human blood.

L1CAM epitopes of the ectodomain are shown to be co-expressed on single-EVs with the neuronal proteins β-III-tubulin, GAP43, and VAMP2, the levels of which increase in parallel with the enrichment of L1CAM-positive EVs. Levels of L1CAM-positive EVs carrying the neuronal proteins VAMP2 and β-III-tubulin range from 30-63%, in contrast to 0.8-3.9% of L1CAM-negative EVs. Plasma fluid-phase L1CAM does not bind to single-EVs.