Biology Reference
In-Depth Information
INTRODUCTION
ling of
in vitro
cultured cells
has proven to be an invaluable tool for under-
standing biological/pathological processes and
holds excellent potential for biomarker develop-
ment.
1
However, it is critical that diseased and
healthy cells/tissues are pro
Molecular pro
led directly
in vivo
at the site of the pathological process within the
tissue microenvironment.
2
Molecular pro
les
obtained from tissue may lead to distinct insights
that are not readily evident using
in vitro
cultured
cells. For this reason, molecular pro
ling of clin-
ical tissues is increasingly used in biomarker
research employing advanced mass spectrom-
etry (MS) technologies.
3
e
5
Processing tissue for
proteomic analysis requires several steps that
must be carefully conducted.
Tissue is de
ned as an aggregate of cells found
in an organism that are characterized by similar
function and structure. The basic types of
mammalian tissues are epithelial, nerve, connec-
tive, muscle, and vascular tissue. Two or more
tissues functionally linked around a speci
c task
form an organ (e.g., liver, kidney). Based on the
physical attributes characterizing organs/tissues
and their suitability for homogenization, they
can be divided into soft (e.g., brain, liver), elastic
(e.g., muscle, skin), and hard (e.g., bone, cartilage)
tissues. Tissue preparation is complex, often
encompassing a greater number of experimental
steps and sample variables compared to cultured
cells.
3,6
As shown in
Figure 1
, tissue preparation
includes acquisition, evaluation, storage, homog-
enization, protein extraction/solubilization, and
digestion. These processing steps are typically fol-
lowed by fractionation to reduce sample
complexityprior to liquid chromatography
e
mass
spectrometry (LC-MS) analysis. Tissue selection
and upstream sample preparation are critical
steps for any biomarker study using MS-based
proteomics. Regardless of the origin, tissue speci-
mens must be procured and stored in accordance
with legal and ethical regulations and protocols.
Every step
d
including the experimental design,
FIGURE 1
Workflow depicting tissue using MS-based
clinical proteomics.
donors
cation, tissue quality assessment,
pathology review/diagnosis, and preparation
for MS analysis
d
must be carefully planned and
executed.
'
identi
TYPES OF TISSUES AVAILABLE FOR
MS-BASED PROTEOMICS
Currently, there are two distinct types of
archived tissues available for molecular pro
ling
using MS-based proteomics. These are fresh or
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