This separation can be done only with an extremely precise technique such as laser-based microdissection
. Laser-based microdissection
has been combined with ProteinChip technology to identify protein markers in other cancers (5-11).
Topics include chlorophyll degradation during senescence, laser microdissection
of plant tissue, uncoupling mitochondrial proteins, the biochemistry of seed flavonoids, cell type-specific gene expression, and leaf hydraulics.
Target cells for protein microarrays are gathered using laser-capture microdissection
, a technology developed in the late 1990s to tease out normal, premalignant, and tumor cells from tissue samples.
(26-33) Some studies have used laser capture microdissection
(LCM) to enrich disease-specific material and enhance the probability of discovering biomarkers.
Molecular Machines and Industries AG's SL [mu]CUT system uses a 348 nm UV laser diode, while Bio-Rad's Clonis system and Arcturus' PixCell IIe Laser Capture Microdissection
System favor IR lasers, as the sample can be damaged or chemically altered by high frequency UV lasers.
For scraping, a scalpel or a razor blade or a dissecting needle is used to scrape cells directly from the entire slide (in cases where microdissection
is not necessary) or from circled tumor-rich areas (in cases where tumor enrichment is required).
coupled with SELDI-TOF MS can overcome these limitations (18), but it is a time-consuming and labor-intensive procedure.
Next come contributions discussing confocal scanning laser microscopy, quantitative computer-assisted image analysis, laser scanning cytometry, laser capture microdissection
, microarray image scanning, near-field scanning optical microscopy, atomic force microscopy, and reflection contrast microscopy.
The ultimate linkage of candidate biomarkers to the actual causal processes that lead to specific toxic effects will be accomplished through studies involving in situ hybridization, immunohistochemistry, and the laser-capture microdissection
of cells to relate the expression of the putative biomarkers to the specific cells that have undergone these adverse events.
Some of these individualized techniques include: fluorescence imaging and chemiluminescence imaging, both offered by Molecular Devices; gel and blot imaging from Amersham; fluorescence correlation spectroscopy from Zeiss; laser microdissection
from Leica Microsystems; and multi-well imaging from Atto.