Karin Schütze

Noncontact Laser Microdissection and Catapulting for Pure Sample Capture

The understanding of the molecular mechanisms of cellular function, growth, and proliferation is based on the accurate identification, isolation, and finally characterization of a specific single cell or a population of cells and its subsets of biomolecules. For the simultaneous analysis of thousands of molecular parameters within one single experiment as realized by DNA, RNA, and protein microarray technologies, a defined number of homogeneous cells derived from a distinct morphological origin are required. Sample preparation is therefore a very crucial step preceding the functional characterization of specific cell populations. Laser microdissection and laser pressure catapulting (LMPC) enables pure and homogeneous sample preparation resulting in an increased specificity of molecular analyses. With LMPC, the force of focused laser light is utilized to excise selected cells or large tissue areas from object slides down to individual single cells and subcellular components like organelles or chromosomes. After microdissection, the sample is directly catapulted into an appropriate collection vial. As this process works entirely without mechanical contact, it enables pure sample retrieval from morphologically defined origin without cross-contamination. LMPC has been successfully applied to isolate and catapult cells from, for example, histological tissue sections, from forensic evidence material, and also from tough plant matter, supporting biomedical research, forensic science, and plant physiology studies. Even delicate living cells like stem cells have been captured for recultivation without affecting their viability or stem cell character, an important feature influencing stem cell research, regenerative medicine, and drug development. The combination of LMPC with microinjection to inject drugs or genetic material into individual cells and to capture them for molecular analyses bears great potential for efficient patient-tailored medication.

6 – Noncontact Laser Microdissection and Pressure Catapulting: A Basic Tool in Genomics, Transcriptomics, and Proteomics

Noncontact Laser Microdissection and Pressure Catapulting: A Basic Tool in Genomics, Transcriptomics, and Proteomics Cellular dissection and micromanipulation techniques have become important in genomic, transcriptomic and proteomic research. Among various options for specimen capture, only the PALM laser microdissection system enables the transfer by means of focused laser light, which allows noncontact sample preparation—a paramount prerequisite for pure sample generation. The chapter discusses the noncontact laser microdissection and pressure catapulting, which is a basic tool in genomics, transcriptomics, and proteomics. The microdissection and capture system are based on the patented laser pressure catapulting (LPC) technology; in LPC, the sample transfer from the objective plane toward a collection device is solely driven by a laser-induced transportation process. In principle, a pulsed nitrogen laser is coupled through the epifluorescence path into an inverted microscope and focused to a micron-sized spot via the objective lenses. By this means, the microscope known as an opto-analytical device has become a most versatile micromanipulation tool: selected specimen of differing origins can be first laser microdissected and thereafter ejected directly into a capture device only by the force of focal light. Thus, the PALM micromanipulation system has no physical or mechanical contact to the specimen so the risk of contamination or infection of the isolated probes is minimized.