[Sharper diagnostic tool the future promise of laser-assisted microdissection]

The paper describes the use of laser-assisted microdissection to retrieve microscopically defined cell populations including single cells from tissue sections for subsequent analysis of genomic DNA and mRNA. A general background is given on the techniques available and requirements for PCR based on minute templates. Different pre-PCR approaches are briefly described and possibilities and limitations of using archival material compared to fresh frozen tissue are discussed. In the article we give one example on how we have used the PALM laser microscopy system in combination with a nested, multiplex PCR system to analyze single normal keratinocytes as well as tumor cells from a case of basal cell cancer. We found that p53 mutations are common in normal, chronically sun-exposed skin. Widespread yet common mutations in the p53 gene that were unrelated to immunoreactivity for the p53 antibody were found in tumor cells. In addition there were rare mutations in occasional tumor cells that apparently did not result in selective growth advantage. Perspectives for the future are presented and the potential of laser assisted microdissection is highlighted within the fields of cancer research, developmental studies as well as studies of inflammatory and degenerative diseases. The combination of a method that allows careful selection of defined cells with powerful micro array based techniques, provides a setting with potential to uncover pathogenic mechanisms for large variety of human diseases.