DMMC Course: TECHNIQUES & STRATEGIES IN MOLECULAR MEDICINE

1610-1650 Friday 10 December 2004. Houston Lecture Theatre, RCSI

Laser Capture Microdissection, tissue arrays, in situ hybridisation Dr Orla Sheils, TCD

Laser Capture Microdissection is a method for procuring pure cells from specific microscopic regions of tissue sections. Under the microscope, tissues are heterogeneous complicated structures with hundreds of different cell types locked in morphologic units. In disease pathologies, the diseased cells of interest are surrounded by these heterogeneous tissue elements. Laser Capture Microdissection constitutes an essential upstream technology to molecular analysis methods studying evolving disease lesions in actual tissue.

In Situ Hybridization techniques allow the demonstration of specific nucleic acid sequences within their cellular environment. A logical extension of early in situ hybridization (ISH) techniques, which exploited the ability to label DNA with high-energy fluorophores, is FISH. This technique is now applied in an increasing number of molecular diagnostic areas, including karyotype analysis, gene mapping, disease diagnosis, and therapeutic targeting.

Tissue Microarrays are produced by a method of re-locating tissue from conventional histology paraffin blocks such that tissue from multiple patients or blocks can be seen on the same slide. Unlike cDNA or SNP arrays, tissue microarrays comprise spotted collections of unique tissues or tumours. TMAs are amenable to a wide range of techniques including histochemical stains, immunologic stains with either chromogenic or fluorescent visualization, in situ hybridization (including both mRNA ISH and FISH), and even tissue micro-dissection techniques.