An exosome is a vesicle with a lipid bilayer structure secreted by cells with a diameter of 30~150 nm, which is released from cells in the form of exocrine secretion after the fusion of intracellular multivesicular body and cell membrane. The shape of the exosome is similar to a saucer or a hemisphere with a concave side. The donor cells of exosomes come from various sources, such as dendritic cells, lymphocytes, platelet, macrophage, epithelial cell, endothelial cell, and nerve cells. And the functions of exosomes secreted by the same cell are different in different physiological environments.
Exosomes widely exist in cell culture supernatants and various body fluids (blood, lymph fluid, saliva, urine, semen, breast milk), carrying a variety of proteins, lipids, DNA, mRNA, and miRNA, etc. related to cell origin, and participate in intercellular communication, cell migration, angiogenesis, and immune regulation. Up to now, according to the statistics of the Exocarta database, 9769 kinds of proteins, 3408 kinds of RNA, 2838 kinds of microRNA, and 1116 kinds of lipids have been found in exosomes. Therefore, exosome has great potential and value in disease diagnosis, treatment, and prognosis assessment.
The extraction and purification of exosomes is the main problem limiting its research and application. The main reason for the problem is that body fluid and other samples contain many substances with similar size and properties to exosome, making it difficult to purify exosomes completely. Obtaining high-quality and effective exosomes is the first step in the study of exosomes. Extracting exosomes with complete structure, high concentration, and high quality effectively while eliminating the interference of other substances is the premise and key to carrying out exosome research.
The commonly used extraction methods in previous experimental studies, including ultracentrifugation, PEG precipitation and others, generally have the problems of low purity and recovery rate. Ultracentrifugation is the most commonly used method for exosome extraction and purification, which uses low-speed centrifugation and high-speed centrifugation alternately to separate similar vesicle particles. The ultra-high-speed centrifuges are expensive, low in popularity, and time-consuming. Repeated centrifugation operations will easily lead to cell destruction and reduce sample quality, limiting the rapid extraction of exosomes by ultracentrifugation in general laboratories.
Polyethylene glycol (PEG) can combine with hydrophobic proteins and lipid molecules to produce precipitation. Over half a century ago, the polymer precipitation method was applied to enrich and purify viruses in serum. Because exosomes and virus particles have similar sizes and biochemical properties, PEG is currently used to extract exosomes. Due to its strong hydrophilicity, PEG will absorb the water molecules around exosomes in the solution, which reduces the water content of exosomes and then aggregates. And then, under low-speed centrifugation, the aggregates can be precipitated. This simple method can be extracted with high flux and rapidly enrich large-volume samples. However, the purity of the exosomes obtained is low, and there may be substances that interfere with downstream experiments, such as Argo2 protein, which may interfere with the sequencing of exosomes nucleic acid.
Guochu Technology has developed a new exosome filtration technology that can separate and purify biomolecules quickly and efficiently. This technology adopts the principle of crossflow filtration, and the pump pushes the sample through the surface of the filter membrane to scour away the molecules trapped on it to minimize the fouling accumulated on the membrane surface. The pressure close to the filter membrane is generated in the retentate fluid to filter the solute and small molecules to the other side of the membrane to achieve the purpose of separation and complete the filtration and concentration of the sample.
Technical features and advantages:
1. Simple operation, small footprint, and it can work as long as connect the device, which is suitable for use in the laboratory;
2. Fast and efficient, easy to assemble, fast processing speed, and it can obtain a higher concentration of samples in a shorter time;
3. The synchronous operation, complete sample concentration and infiltration in the same system, save time and avoid the loss of products, and retain the sample size to a large extent;
4. Corresponding devices can be provided to handle samples as low as 10mL or as high as kiloliter.
The exosome filtration technology of Guochu Technology can ensure consistent filtration effect and high filtration volume without destroying the biological activity of exosomes, simplify the filtration process and streamline the processing. It solves the problems of low purity and low recovery rate of exosomes in traditional extraction methods, reduces operation time, reduces sample loss, improves sample recovery rate, enhances exosome purity, and improves experimental efficiency. For more information on exosome filtration technology, please call +86-592-6518670.
