Laser microdissection

Abstract

Solid tissues and organs, especially diseased tissues, are complex structures composed of heterogeneous mixtures of morphologically and functionally distinct cell types. The purposeful molecular study of cytologically and/or phenotypically specific cell types from tissues either normal or often more importantly abnormal or diseased requires the availability of rapid, efficient and accurate methods for obtaining specific defined groups of cells for further study. Whereas for example circulating blood cells can readily be separated into their distinct morphological and phenotypic classes by cell sorting using flow cytometry obtaining specific types of cells from solid tissues for analysis has until recently been much more difficult. Although manual methods of tissue microdissection have been described they are slow, cumbersome and not very specific. However, the development of laser based methods of microdissection for selecting specific types of cells from thin sections of tissues with direct microscopic visualisation of the process has greatly facilitated the appropriate and meaningful molecular analysis of specific types of cells and thus providing new insights into normal cell biology and disease mechanisms. There are two major systems for performing laser-Assisted tissue based microdissection namely laser capture microdissection and laser cutting microdissection and both types of system have now been commercially available for several years. This chapter will outline the principles of these technologies and consideration will also be given to the main downstream molecular applications. There are a wide range of powerful and increasingly sophisticated molecular technologies including expression microarrays and proteomics which are now available to analyse the biology of cells. To fully exploit the value of these technologies in the analysis of specific tissues or organs requires that the investigator must be certain that the appropriate type or types of cells are analysed. Laser based microdissection techniques have allowed this to be achieved in a straightforward and non-time consuming manner. It is now even possible to microdissect a single cell and analyse its molecular properties. There are two different technologies that have been developed for laser based microdissection systems. One technology is laser capture microdissection using an infra red laser while the other technology is based laser cutting using an ultraviolet laser. With either of these technologies it is possible to mcicrodissect cells based on their morphology or select cells according to their phenotype. Positive or negative selection of cells is also possible i.e. The microdissection acquires the cells of interest or microdissection is used to remove all the unwanted cells leaving behind the cells of interest. © 2008 Humana Press.