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Tissue Microarrays: Current Status
By Anil Sehgal Ph.D.
With the cost of drug discovery and development increasing, there is
critical need for tools and technologies that can reduce the cost or time length
from discovery to marketing of a product. In the past decade, a large number of
gene targets have been identified, and it is estimated that there are over
30,000 genes that may encode for over 100,000 proteins. With such a huge number
of potential gene and protein targets being identified, the pharmaceutical
industry is faced with the daunting task of filtering targets to pick the right
ones for further development. Target validation is a critical step in sifting
through such targets, allowing for identification of lead compounds for serious
development consideration. In the past, target validation was done with static
assays such as Northern blot analysis, RT-PCR, macroarray, microarray, and gene
chips. With these technologies, even though the differential expression of
specific genes can be evaluated, only rudimentary clinical information is
obtained. In the majority of molecular biology techniques, tissue is homogenized
to isolate the RNA for expression analysis. Furthermore, the tissue obtained is
not made up of only the disease cell population. Such a tissue homogenate can
contain normal cells, tumor cells, blood cells, muscle cells, and other cell
types that may dilute and/or result in misleading information. In the majority
of drug discovery cases, target validation is done by analyzing expression of
genes and proteins in tissue samples. In the past, most target validation was
done one tissue at a time on single slide section. Such studies require large
amount of precious human tissue samples.
With the inception of tissue microarray technology, it is now
possible to study the expression of a single gene target in hundreds of human
tumor or normal tissue samples. One of the shortcomings of the tissue microarray
technology is that only a small portion of the tissue section is represented.
Tissue microarray vendors are now picking tissue samples from multiple different
areas to overcome this problem. With hundreds of tissue samples from discovery
and clinical studies, the amount of information generated from tissue
microarrays is increasing at a fast pace. To overcome this problem, several
companies have developed devices, scanners, automated scanners, and software.
Pathologists in major hospitals and research centers are now utilizing several
tissue microanalysis instruments and software. One of the major bottlenecks that
has been realized in the past few years is the quantitative, efficient, and
specific analysis of the data generated from tissue microarrays. Extensive
progress has now been made in the analysis of tissue microarrays by several
vendors listed below (Table 1). Tissue microarray analysis can now be done based
on staining intensity, shape, as well as mitotic figures. Additional software is
also being developed to analyze expression of particular antigens on the cell
membrane. As the evolution of tissue microarray analysis and application takes
place, it will continue to make fruitful contributions in speeding and reducing
the cost of drug discovery and development.
Table 1
Tissue Microanalysis: Vendors and Products
|
Company |
Product Information |
|
Aperio Technologies |
ScanScope Systems - Instrumentation & software for virtual microscopy
ScanScope T2 - Ultrafast slide scanner
ImageServer - Access virtual slides efficiently
Annotation Authoring - Annotation authoring software for
ImageScope
ImageScope - Virtual slide viewing software
TMALab - Organize, analyze, and share tissue microarray data
|
|
BioImagene |
PATHIAM - Information driven, histopathological and cytopathological
image analysis, quantification, management, and retrieval software system;
Based on a self learning framework that uses artificial intelligence and
expert systems; Analyzes images based on color intensity and morphological
patterns; Lends itself to customization and remote communication; Powered by
iHARNESSTM, a patent pending expert system framework for analyzing
histopathological and cytopathological biopsy slides, stained with either
hematoxillin-eosin or immunohisto-chemical reagents. |
|
Bacus
Laboratories |
BLISS - Next-generation microscope imaging workstation
WebSlide Browser - For viewing digital microscope slides with
diagnostic quality
IHCscore - Quantitative tissue scoring; Easily select measurement
regions directly on the virtual slide using mouse
TMAscore - Quantitative tissue microarray scoring
SlideTray™ - Keep virtual slides organized on your personal
computer |
|
Chromavision Medical Systems |
Automated Cellular Imaging System (ACIS) - Quantifies staining
intensities, percent positive nuclei, and area measurements on
immunohistochemically stained tissue sections; ACIS quantitation provides an
objective analysis that allows for precise, reproducible, and standardized
results. |
|
Molecular Devices |
Discovery-TMA™ - High-speed automated optical platform and integrated
software system optimized for the acquisition, processing, and analysis of
images from tissue microarrays; System enables a revolution in assay
development by bringing high content screening technology to tissue
microarray applications. |
|
Tissue Informatics |
TissueAnalytics™ - A protocol driven, study-based tissue analysis
software package for the data management, processing, and automated
quantitative analysis of histological slides; Software automatically
determines immunostain area and intensity, enables fixed reference
comparisons, and quantifies identified structural elements within tissue -
including cells, vasculature, and matrix organization - by a range of
feature metrics, such as type, shape, size, and distribution. |
Source: D&MD.
This
update was written by Anil Sehgal Ph.D., Freelance Writer, Dublin, CA. He may be
contacted via e-mail at
cancersci@hotmail.com.
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view and purchase D&MD reports click
here!
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