Primary cells for in vitro research are widely used in biomedical studies because they closely represent the natural characteristics and biological behavior of cells in the human body. Researchers use primary cells to investigate disease mechanisms, drug responses, toxicity, cell signaling, and molecular pathways. Compared with immortalized cell lines, primary cells can provide more physiologically relevant results for many experimental applications. They are valuable in cancer research, immunology, tissue studies, and therapeutic development. High-quality primary cells can help researchers conduct reliable and reproducible in vitro research. When selecting primary cells, researchers should consider factors such as cell type, donor information, quality, viability, and experimental requirements. Reliable primary cell products can support advanced research and help scientists gain meaningful insights into complex biological processes.