Methods and kits for exosome isolation and quantification

A method for isolating exosomes in a sample, comprising the steps of,

• (a) contacting a plurality of lectin-modified magnetic beads with the sample to obtain a first mixture, wherein the plurality of lectin-modified magnetic beads are suspended in an exosome-free buffer, and each lectin-modified magnetic bead comprises a plurality of lectin molecules that are covalently bonded to the magnetic bead, wherein the exosome-free buffer is an exosome-free bovine serum albumin or exosome-free human serum albumin, and the lectin is galectin-3;
• (b) incubating the first mixture at a condition allowing the exosomes to conjugate with the lectin molecules of the lectin-modified magnetic beads thereby obtaining a second mixture comprising a plurality of exosome-bead complexes;
• (c) subjecting the second mixture from the step (b) to a magnetic field, thereby separating the exosome-bead complexes from the remainder of the second mixture;
• and
• (d) separating the exosomes from the magnetic beads by eluting the exosome-bead complexes from the step (c) using an elution buffer having a pH value of 6.8 to 7.6, wherein the elution buffer is a lactose solution consisting essentially of lactose.