An Isolation System to Collect High Quality and Purity Extracellular Vesicles from Serum

Jian Yang,1,2 Xin Gao,1,2 Xiaotao Xing,1,2 Haisen Huang,1,2 Qi Tang,1,3 Shixing Ma,1,2 Xun Xu,1,2 Cheng Liang,1,2 Maojiao Li,1,2 Li Liao,1,2 Weidong Tian1,2 1State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Engineering Research Center of Oral Translational Medicine, Ministry of Education & National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, People’s Republic of China; 2Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, People’s Republic of China; 3West China School of Public Health & West China Fourth Hospital, Sichuan University, Chengdu, 610041, People’s Republic of ChinaCorrespondence: Li Liao; Weidong TianState Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Engineering Research Center of Oral Translational Medicine, Ministry of Education & National Engineering Laboratory for Oral Regenerative Medicine, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, People’s Republic of ChinaTel/ Fax +86-28-85503499Email lliao@scu.edu.cn; drtwd@sina.comPurpose: Extracellular vesicles (EVs) are membrane-encapsulated nanoparticles that function as carriers and play a role in intercellular communication. There are a large number of EVs in the blood and serve as an indicator of pathophysiological conditions. Studies on the basics and application of EVs are hampered by the limitations of current protocols to isolate EVs from blood. However, current isolation methods are difficult to achieve a balance between yield and purity.Methods: Firstly, we use Sepharose-4B to build a self-made size exclusion chromatography (SEC) column and perform separation and characteristics. Then, we use the SEC column to systematically compare the efficiency with the most common EV isolation methods: Ultracentrifugation (UC) and total exosomes isolation commercial kit (TEI). The EVs isolated through different methods were characterized the yield and size of EVs, analyzed their protein profiles, the morphology and purity were observed under the transmission electron microscope. To further improve the quality and purity, we combined SEC and UC methods and established a two-steps method to isolated EVs from serum.Results: Self-made SEC column can well separate EVs from complex serum protein, and EVs enriched in the 8– 13 fractions with good morphology and yield. By systematically compare SEC with the commonly used UC and TEI kit, SEC is outstanding in all aspects and balances both isolation purity and yield. However, using the SEC method alone still has certain limitations and residual impurities. The SEC+UC combined method can cleverly solve the shortcomings of SEC and optimize the quality and purity of EVs from serum, which is much better than using one method alone.Conclusion: Our study presents the combination of size-exclusion chromatography and ultracentrifugation as a feasible and time-saving method to isolate high-quality and purity extracellular vesicles from serum.Keywords: extracellular vesicles, size-exclusion chromatography, ultracentrifugation, total exosomes isolation, combination methods