Image-Based High-Content Analysis, Stem Cells and Nanomedicines: A Novel Strategy for Drug Discovery - Harnessing Biomaterials in Nanomedicine: Preparation, Toxicity, and Applications - page 267

immortalized or cancerous cell could have vast diff erences in its gene
expression pattern and, in turn, in its biochemistry, when compared
with its non-immortalized counterpart. Recent advances in stem cell
(SC) technology have the potential to allow production of a virtually
limitless supply of normal human cells that can be diff erentiated
into any specific cell type, except those cell types that make up the
extra-embryonic tissues such as the placenta [15]. If this potential is
realized, we may witness a leap in our ability to screen for new cell
type specific drugs.
SC can diff erentiate into clinically relevant cell types with
uniform physiological characteristics that allow improved target
validation decisions [16]. Additionally, SC may allow inclusion of
previously unavailable cell types to be used to screen the libraries of
therapeutic candidates [17].
These reasons make the use of SC for image-based high-content
screening a very valuable option for novel drug discovery.
9.3.1 StemCells
During the first stages of life for multi-cellular organisms, a fertilized
oocyte is the progenitor for an entire organism. This single cell
creates all the diff erent tissues and cell types with all their various
characteristics and functions needed to perform as a multicellular
organism. During embryogenesis, cells both proliferate and
diff erentiate, thus enabling the growth of tissues and organs.
In an adult organism, most tissues and organs maintain a
homeostasis wherein cells continually die and are continually
replenished. The extent of this ability varies considerably among
organisms and among diff erent types of tissues. Some flatworms are
capable of regenerating most of their bodies and even use this as a
method of reproduction by splitting into two parts, with each half
subsequently repairing itself into a whole [18-21]. While mammals
in general and humans specifically do have regenerative capabilities,
they do not enjoy anything similar to this spectacular level of plasticity.
The liver, epidermis, small intestine and hematopoietic system are a
few examples of relatively replenishable cells in mammals [22-25].
We owe this fantastic and necessary capability to SC.
SC are capable of undergoing both self-renewal and diff erentiation
into specific specialized cell types. Embryonic stem cells (ESC) are
pluripotent; hence, they bear the potential to produce all the cell types