Live-cell imaging and analysis allows scientists to study dynamic cellular events in real time to gain unique insights into biology. These techniques are in contrast to PCR, flow cytometry, and immunocytochemistry and tissue staining with antibodies, which analyze cellular events as a snapshot. Today, improvements in cameras, live-cell fluorescent dyes, fluorescent proteins, video compression, and time-lapse microscopy have advanced our ability to visualize and analyze living cells, their intercellular interactions, and subcellular processes with remarkable detail and fidelity.
A variety of techniques are used to visualize the complex structures and behavior of cells. In static analyses, cells are fixed and stained, which requires killing the cells and therefore capturing a single instant in cellular time. While static techniques are suitable for some applications, they do not provide insight into cellular activities. Dynamic, live-cell approaches facilitate the visualization of structure, behavior or composition in live cells, without traditional staining. These techniques are ideal for applications that must mimic in vivo conditions, as well as for developing predictive assays for drug screening.
Live-cell imaging systems use advanced optics, environmental control, and reagents that permit long-term studies of mammalian, bacterial, and yeast cells. Culture and imaging systems that also employ microfluidics allow precise control of the culture microenvironment, like flow, gas mixture, and temperature, while limiting physical stress to cells. Live-cell imaging and analysis is suited to a range of applications, including hypoxia, cell migration, 3D cell culture, cytoskeletal dynamics and protein trafficking. Advanced systems automate culture conditions, administration and withdrawal of treatments, and imaging intervals to create images that may be presented as still image or video data.
Live-cell imaging media and supplements are designed to protect cells from light-induced cellular damage during time-lapse experiments. These reagents are also formulated to have low autofluorescence and photobleaching, which dramatically enhances the quality of fluorescent live-cell images.
A variety of live-cell staining dyes are available to study the dynamic processes of live cells. Live-cell fluorescent organelle dyes permit the selective staining of specific organelles, such as the cell membrane, nucleus, cytoplasm, mitochondria, lysosomes, endoplasmic reticulum (ER), Golgi apparatus, and cytoskeleton proteins, all without increased cytotoxicity. Using organelle dyes as counterstains in live-cell imaging is also useful in functional studies.
Biosensors with GFP and RFP can be used to detect a specific protein as well as the subcellular location of that protein within live cells by either fluorescent microscopy or time-lapse video capture. Lentiviral vector systems are a popular tool for introducing genes and gene products into cells, with many advantages over chemical-based transfection. Beyond organelle detection, cell-permeable live-cell dyes are used for applications such as apoptosis detection, cell viability, cell health, hypoxia, reactive oxygen species studies, calcium indicator imaging, and neural or stem cell experiments.