Live Cell Imaging

Short definition:
Live Cell Imaging is a method to optically investigate living cells over a period of time using time-lapse microscopy. Thus, processes such as fertilization and cellular development, cell signaling, cell migration or cell differentiation can be envisioned and comprehended.

What is Live Cell Imaging?

Live Cell Imaging is a method to optically investigate living cells over a period of time using time-lapse microscopy. Therefore, cells can be monitored over long periods of time to be able to visualize very slow processes that are below the threshold of human perception. Typical applications of live cell imaging experiments include cell migration, wound healing, as well as fertilization, cell development and differentiation processes.

How does Live Cell Imaging work?

In live cell imaging, living cells are observed over a period of time under a live cell imaging microscope. To allow for automated live cell imaging workflows, today’s live cell imaging solutions mainly consist of a fully motorized research microscope, including a digital microscope camera and a dedicated software solution to design and run the experiment as well as to analyze the data. Images of a single field of view or even of the whole sample area are recorded sequentially after certain time points over a longer period of time. To keep cells in physiological conditions throughout the experiment, live cell imaging systems are typically equipped with incubation chambers to precisely control temperature, humidity and CO2 concentration. It is essential that these parameters can be adjusted to the cells’ requirements and that they can be kept at a constant level for the entire period of the experiment.

Cells can be imaged with different imaging modes such as brightfield microscopy, supported for example by phase contrast methods. In addition, several live cell imaging techniques have evolved using specific live cell imaging fluorescent dyes to be able to identify cells of interest and also to selectively monitor development, differentiation or viability of the cells. Thus, live cell fluorescence microscopy is a helpful tool which can visualize a lot of additional information on the individual cells. Live cell super resolution microscopy or 3D live cell imaging provide additional depth and insights into the analysis of living cells.

The recorded images can be opened, viewed and analyzed using dedicated live cell analysis software packages. The series of single images can be turned into live cell imaging videos and the software algorithms provide detailed analyses of cells over time such as trajectories of migrating cells. Time is therefore not just another dimension in live cell imaging, but it allows to perceive processes which we would otherwise not be able to sense.

When did Live Cell Imaging first emerge?

“The Cheese Mites” by Martin Duncan has been recorded in 1903 and is one of the first microcinematographic films. In 1907, Julius Ries used this new method to teach medical students. He made one of the first time-lapse films showing the fertilization and development of the sea urchin egg. Individual images were taken during live cell microscopy experiments already in the 19th century. However, the sequential recording of images and their analysis with live cell imaging now allowed to study cellular processes in more detail. Today, live cell imaging can be performed in many imaging modes, such as phase contrast, fluorescence imaging, confocal imaging, super resolution imaging or 3D imaging. With the introduction of digital cameras in the early 2000s, live cell imaging has become easily accessible. Time-lapse settings can be pre-defined for automated recording of the individual images and thus also allows for long-lasting hands-off experiments. A still increasing number of scientific publications include live cell imaging data thus highlights the importance of spatiotemporal analysis of cells.

When is Live Cell Imaging used?

Live Cell Imaging is applied to visualize very slow cellular processes, which are typically below the threshold of human perception. Thus, processes such as fertilization and cellular development, cell signaling, cell migration, or cell differentiation can be envisioned and comprehended. In addition to basic research, live cell imaging plays an important role in drug discovery and development.

Live cell fluorescence imaging allows to selectively stain different cell types as well as cells in diverse differentiation stages providing profound insights into cellular mechanisms and processes. In addition, fluorescent dyes can also be applied to stain cellular compartments and structures. Therefore, even the dynamics within a cell can be visualized in live cell imaging experiments for example during development or cell migration.

What methods & techniques are there for Live Cell Imaging?

To study detailed cellular processes, live cell imaging can be combined with different microscopy technologies. Live cell fluorescence microscopy or live cell super resolution microscopy provide detailed insights into cellular identity and dynamics. Fluorescent dyes can be coupled to antibodies which target cell surface proteins specifically for one cell type or developmental stage. Moreover, cellular structures can be selectively visualized as the protein components can be expressed as fluorescent fusion proteins such as GFP fusion proteins. 3D live cell imaging adds an additional dimension to the spatiotemporal analysis of a cell. Dedicated live cell analysis systems are commercially available today and offer both hardware and software solutions for high-end live cell imaging.

How do the solutions of MMI help me with Live Cell Imaging?

With the MMI CellScan, MMI offers an open platform for whole slide imaging and scanning to provide digital images in full resolution. Time-lapse options, multi-color fluorescence imaging as well as z-stack settings provide detailed insights into the live cell culture as well as into single cells. The MMI CellScan system is based on a standard research microscope which can be individually configured with microscope objectives, fluorescence light sources and filter sets as well as with incubation chambers of your choice to optimally fit the system to your application and your requirements in live cell imaging.

Intriguingly, the MMI CellScan can be uniquely combined with all other MMI systems, such as the MMI CellManipulator to manipulate or measure forces between individual cells, the MMI CellCut to excise single cells using laser microdissection, or the MMI CellEctor to pick individual cells using an automated capillary-based system. Both systems, the MMI CellCut and the MMI CellEctor can be employed to isolate single cells from cell culture conditions into tubes or petri dishes for sequencing or further cultivation, respectively. The MMI CellScan can also be combined with the MMI CellExplorer software module which can identify target cells based on parameters such as fluorescence and size. Live cell imaging can therefore be easily combined with image recognition and single cell isolation technologies.

Since all systems are integrated on the MMI CellTools software platform, workflows covering more than one device can easily be conducted without switching the software interface and without losing spatial information between the different applications. Possible workflows using the MMI CellTools platform can cover scanning or live cell imaging, automated identification of target cells and their selective isolation into new cell culture dishes. Re-cultivation, development or differentiation of the isolated cells can again be followed by live cell imaging.