Laser micromanipulation systems as universal tools in cellular and molecular biology and in medicine.

The UV-laser microbeam has been established as a valuable tool in a wide area of molecular biology as well as in medical research and applications. This system allows to cut or fuse microscopically small specimen. An important application of the cutting laser is laser microbeam microdissection (LMM) combined with laser pressure catapulting (LPC), which allows to procure single cells or small homogeneous cell areas for subsequent molecular analysis in an entirely "non-contact" manner. With LMM minute tissue areas, single cells or chromosomes are microdissected and separated from their surroundings. Subsequently, LPC ejects the dissectates directly into the cap of a sample tube without any mechanical contact. This enables the rapid procurement of homogeneous specimen from less than one up to several hundreds of micrometers in diameter without encroachment of the adjacent region. The mRNA information of the selected specimen as well as of the remaining probe are well preserved, as demonstrated with laser isolated samples from a routinely prepared tissue section of a differentiated colorectal adenocarcinoma. Reverse transcription of specific mRNA coding for cytoplasmic beta-actin and subsequent hemi-nested PCR amplification was not impaired. Any kind of tissue, as well as single cells from different sources and even subcellular structures can be captured using this laser method. Wherever homogeneous samples are required to analyze cell or chromosome-specific genetic alterations such as in cancer research or prenatal diagnosis this unique and rapid laser micropreparation method will become a key technology of great value.