Repligen Corporation, a life sciences company, develops and commercializes bioprocessing technologies and systems in North America, Europe, the Asia Pacific, and internationally. It offers Protein A ligands that are the binding components of Protein A affinity chromatography resins; and cell culture growth factor products. The company also provides chromatography products, including OPUS pre-packed chromatography columns, which are used in the purification of biologics; and OPUS smaller-scale columns that are used in the high throughput process development screening, viral clearance validation studies, and scale down validation of chromatography processes, as well as ELISA test kits. In addition, it offers filtration products, such as XCell ATF Cell Retention Systems that are filtration devices used in upstream perfusion and cell culture processing; TangenX flat sheet cassettes, which are used in downstream biologic drug concentration, buffer exchange, and formulation processes; KrosFlo tangential flow filtration and tangential flow depth filtration systems; and ProConnex TFDF flow paths.