Laser capture microdissection (LCM) is a technique used in biological laboratories which enables technicians to remove a specified area or type of cells from a sample. A dehydrated cellular sample is placed on the stage of a microscope, and a thin layer of thermoplastic material, such as ethylene vinyl acetate, is then placed on a section of it. When a laser beam is focused on the selected cells, a layer of membrane melts and bonds with them, and these cells become embedded in the film once it is removed. The process is also known as laser microdissection (LMD).
Originally created by the National Cancer Institute, laser capture microdissection is used to study various types of tumors and to analyze and identify the nature of different types of cancers. It enables the study of different parts of tumors and their stages of development. The technique is also utilized for a variety of kinds of genetic analysis and to study complex brain and immunological cells. It can be used in conjunction with other DNA and gene expression experiments.
LCM is not the only type of microdissection procedure. Another type of laser capture microdissection system uses only a laser to separate cell samples. There is no contact between the cells and any type of material, and the energy of the laser itself moves the microdissected cells into a sample vessel. A different system removes unwanted cells with an ultraviolet light, which takes longer to complete but also does not require the use of a polymer film.
Due to its ability to obtain pure samples of cells for molecular analysis, laser capture microdissection has been enhanced through various studies and alterations. It has been found that using frozen tissue yields better results. Adhesives have been used on microscope slides, but instead of helping to attach cells, this makes it difficult to capture specific tissue samples. The presence of moisture has a negative affect on getting cells onto a film, so dehydrated tissue sections are preferred during the technique.
Despite its benefits, laser capture microdissection has a few disadvantages. The costs of the microscopes, computers, and software can be high. It can also be hard to see samples because a microscope slide cover slip is not used, which is a problem with many similar techniques. Researchers also find themselves needing more time to carry out the process, but the purity of the samples obtained with LCM still outweighs the benefits of other methods.