As research links more genes to the predisposition for specific diseases, diagnosticians are clamoring to measure multiple genetic alterations in developing or diseased tissues. However, the contamination of tumor specimens by even a small proportion of non-tumor cells may confound analysis, and the genetic signature of the disease can be lost. To overcome the drawbacks of current tissue microdissection techniques, we have developed a laser capture microdissection (LCM) system. The method entails placing a thin transparent film over a tissue section, visualizing the tissue microscopically, and selectively transferring the cells of interest to the film by a short, focused pulse from a laser. The film with the procured tissue is removed from the section and placed into DNA, RNA, or enzyme buffer for processing. LCM is a simple, one-step procedure requiring no moving parts or manual manipulation. The transferred tissue on the film retains its original morphology, thereby allowing microscopic verification of the efficacy of the targeted transfer, and transfers can be done in substantially less time than an experienced microdissector can do manually. The use of sterile, disposable transfer films minimizes potential contamination, which is particularly important for PCR-based analyses. Using LCM allows PCR detection of the pattern of loss of heterozygosity (LOH) on chromosome 8p in prostate cancer, with sensitivity identical to using manual tissue microdissection. LCM can also be used for recovery and subsequent RT-PCR analysis of mRNA with the targeted sample, thus allowing determination of patterns of gene expression in specific pathologies.
