Size-exclusion chromatography (SEC) was then performed using qEV columns (Izon Science) to further purify the exosomes by size. Eluted fractions containing exosomes were pooled and concentrated using Amicon Ultra-15 centrifugal filters with a 100 kDa molecular weight cutoff. The final purified exosome preparations were stored at -80°C for subsequent characterization and experimental use. These well-validated processes for stem cell isolation and exosome purification produced high-purity exosome samples, which were subsequently used in a series of in vitro and in vivo studies to investigate their therapeutic potential for neuroregeneration.