The separation and sorting of cells is essential for basic cell biology research and a variety of biomedical applications including diagnostic and therapeutic applications. Cell separation is mainly based on differences in physical or chemical properties of different cells. Physical cell separation methods include density gradient centrifugation, dielectrophoresis, field-flow fractionation, filtration, and elutriation centrifugation. In these methods, there must be significant differences between size, dielectric potential, buoyancy, or other parameters. Density gradient centrifugation is a common method for the isolation of specific cell populations from whole blood. In cellular sieving methods, cells are separated by size, morphology, and deformability of them. Affinity-based separation has become the commonly used technique for cell isolation because they meet the need for high yield and purity as well as scalability and sterility. In affinity cell separation, ligands such as antibodies, proteins, or lectins bind to unique or overexpressed proteins on the cell membrane of the target population. Fluorescence activated cell sorting (FACS) and magnetic activated cell sorting (MACS) techniques separate cells based on the specific binding of antibodies to cell surface antigens. Antibody-based separation methods are the gold standard for selecting individual cell populations, and both FACS and MACS can be used to isolate cell populations to high purity. Ligands with high selectivity and reduced nonspecific binding contribute to improve the efficiency of affinity cell separation methods. Aptamers are developed as capture molecules for the isolation of rare cells from blood. Aptamers exploit the hydrogen bonding properties of DNA or RNA to produce conformational geometries that preferentially bind to target molecules with high affinity and specificity. Advantages of using aptamers instead of antibodies include ease of synthesis and the ability to capture non-protein targets. Aptamers are also more robust than antibodies and can remain stable for longer periods of time under suboptimal conditions.
Cell separation methods can be divided into positive isolation and negative isolation. The positive isolation techniques are commonly used for cell separation because of high purity of collection. In these methods, cells of interest are collected as the target cell population. Negative isolation techniques isolate the non-specific cells from heterogeneous suspension, leaving the target cells in the suspension. The significant advantage of negative isolation techniques is the ability to separate cells without deleterious labeling or stresses and selectively isolate cells without known markers. Studying the distinct characteristics of a select cell depends on the pure, homogeneous population of desired population in the research system. The enrichment of a target cell population and cultivation of the desired cells from a defined cell population is an important first step in the field of molecular genetics and proteomics, as well as in many basic biological assays. Amerigo Scientific provides products for positive isolation, negative isolation, and depletion to enrich a specific cell population.
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