these are useful in mimicking the early stages of embryonic development occurring
in vivo (Wobus and Loser 2011) (Liu et al. 2013; Mori and Hara 2013).
As the results of toxicological analysis performed using mESCs could not be
applied to humans directly due to inter-generic variations, Cezar and group
introduced use human embryonic stem cells (hESCs) as model in toxicology testing
(Gabriela et al. 2007) to overcome the drawbacks associated with mESCs. They
performed small metabolite-based profiling using mass spectrometry and
demonstrated that hESCs and hESC-derived cell types (for example, neural
precursors) exposed to pollutants could be helpful in elucidating the molecular
mechanisms associated with toxicity. On performing metabolomic profiling using
hESC model, biomarkers for developmental toxicity were identified and it was
demonstrated that the teratogenicity was correctly predicted for 88% of drugs and
83% of environmental toxicants.
Further, fibroblasts derived from hESCs were utilized for in vitro toxicology
screening and it was shown that hESCs derived fibroblasts displayed more sensitive
dose response to mitomycin C treatment in comparison to other in vitro models such
as human lung fibroblast L929 cells (Cao et al. 2008). Several studies utilized hESCs
for specifically assessing toxic effects of drugs or compounds on neural
differentiation only.
12.7 Artificial Niche
Harrison et al. in 1907 reported the first cell culture. Since then, with the advent of
new technology and scientific advancements there has been a tremendous improvement in the techniques of cell culture. These advancement culture methods include
mouse ESCs culture established by Evans (Evans and Kaufman 1981), culture of
human ESC by Thomson (Thomson et al. 1998), mouse iPSC culture establishment
of by Shinya Yamanaka (Takahashi and Yamanaka 2006), and recent establishment
of human iPSC culture by Yamanaka and Thomson (Takahashi et al. 2007; Yu et al.
2007).
With establishment of new and advanced culture techniques it has been accepted
that culture protocols require standardization depending upon the cell type. For
example, in case of umbilical cord blood and bone marrow derived MSCs culture,
tissue culture plate surface (TCPS) using a specific cell culture medium is sufficient
for expansion of MSCs. The TCPS properties allow for the adsorption of the serum
proteins present in medium (e.g. fibronectin, vitronectin, etc.) on the TCPS thereby
supporting cellular adherence. Alternatively, while using human ESCs, iPSC and
several other sensitive cultures including neural stem cells, an ECM protein
pre-coated surface is required.
Although TCPS with various surface treatments are commercially available
which provide charged surfaces and low cellular attachment, these surfaces do not
replicate the true physical and structural cues which are important for determining
the correct cell fate. More complicated culture protocols are required involving early
progenitor cells (e.g. ESCs or GSCs) where stem cell niche interactions are
260
A. Kumar et al.
in vivo (Wobus and Loser 2011) (Liu et al. 2013; Mori and Hara 2013).
As the results of toxicological analysis performed using mESCs could not be
applied to humans directly due to inter-generic variations, Cezar and group
introduced use human embryonic stem cells (hESCs) as model in toxicology testing
(Gabriela et al. 2007) to overcome the drawbacks associated with mESCs. They
performed small metabolite-based profiling using mass spectrometry and
demonstrated that hESCs and hESC-derived cell types (for example, neural
precursors) exposed to pollutants could be helpful in elucidating the molecular
mechanisms associated with toxicity. On performing metabolomic profiling using
hESC model, biomarkers for developmental toxicity were identified and it was
demonstrated that the teratogenicity was correctly predicted for 88% of drugs and
83% of environmental toxicants.
Further, fibroblasts derived from hESCs were utilized for in vitro toxicology
screening and it was shown that hESCs derived fibroblasts displayed more sensitive
dose response to mitomycin C treatment in comparison to other in vitro models such
as human lung fibroblast L929 cells (Cao et al. 2008). Several studies utilized hESCs
for specifically assessing toxic effects of drugs or compounds on neural
differentiation only.
12.7 Artificial Niche
Harrison et al. in 1907 reported the first cell culture. Since then, with the advent of
new technology and scientific advancements there has been a tremendous improvement in the techniques of cell culture. These advancement culture methods include
mouse ESCs culture established by Evans (Evans and Kaufman 1981), culture of
human ESC by Thomson (Thomson et al. 1998), mouse iPSC culture establishment
of by Shinya Yamanaka (Takahashi and Yamanaka 2006), and recent establishment
of human iPSC culture by Yamanaka and Thomson (Takahashi et al. 2007; Yu et al.
2007).
With establishment of new and advanced culture techniques it has been accepted
that culture protocols require standardization depending upon the cell type. For
example, in case of umbilical cord blood and bone marrow derived MSCs culture,
tissue culture plate surface (TCPS) using a specific cell culture medium is sufficient
for expansion of MSCs. The TCPS properties allow for the adsorption of the serum
proteins present in medium (e.g. fibronectin, vitronectin, etc.) on the TCPS thereby
supporting cellular adherence. Alternatively, while using human ESCs, iPSC and
several other sensitive cultures including neural stem cells, an ECM protein
pre-coated surface is required.
Although TCPS with various surface treatments are commercially available
which provide charged surfaces and low cellular attachment, these surfaces do not
replicate the true physical and structural cues which are important for determining
the correct cell fate. More complicated culture protocols are required involving early
progenitor cells (e.g. ESCs or GSCs) where stem cell niche interactions are
260
A. Kumar et al.