Ultracentrifugation is regarded as the gold standard method for exosome isolation. The ultracentrifugation process is time consuming and may introduce protein and nucleic acid contamination. Pre-clearing samples by one or more low speed centrifugation steps will deplete the cells, platelets, and large apoptotic bodies. Larger extracellular vesicles can be pelleted at forces between 10000-20000 x g. Smaller extracellular vesicles can be pelleted at higher speeds, ranging from 100000-200000 x g. Depending on the protocol, it can take up to 24 hours to isolate exosomes by ultracentrifugation. It is impossible to achieve absolute separation due to potential contamination of proteins and nucleic acids.
Exosomes are cell-derived vesicles originating from multi-vesicular bodies and found in biological fluids such as blood, saliva, urine, and breast milk. Sizes of these extracellular vesicles (EVs) range between 30-100 nm. Due to their capacity to transfer proteins, lipids and nucleic acids, exosomes can influence various physiological and pathological functions (Yañez-Mo et al., 2015).
Exosomes play a key role in cell-cell communication and circulate in bloodstream, and therefore, are implicated as a disease biomarker for cancer and immune system disorders. However, there is limited information regarding efficient methods for obtaining pure exosomes. MBL offers a unique exosome purification kit that can help researchers purify exosomes from their sample.