Biomedical Engineering Reference
In-Depth Information
cytotoxic agent at a high concentration, CoCl
2
is a noncytotoxic or weak cytotoxic
agent [
70
]. Therefore, a CoCl
2
solution with a high concentration (50 mM) and
methanol solutions with low (7%, v/v) and a high (7%, v/v) concentrations were
prepared in PBS for toxin exposure experiments. The cytotoxic sensitivity of cells
in the miniaturized hydrogel (initial density 1.0
10
6
cells/mL, 4-day encapsula-
tion) was compared with that of cells in the bulk hydrogel (initial density 1.0
10
6
cells/mL, 4-day encapsulation).
As shown in Fig.
18
, cytotoxicity responses expressed as the percentage of dead
cells were in accordance with the cytotoxicity of the toxins. Exposure to noncyto-
toxic (or weakly cytotoxic) solutions (50 mM CoCl
2
and 7% v/v methanol) resulted
in a very low percentage of dead cells, whereas a cell death of 100% was observed
in exposures to the strongly cytotoxic solution (70% v/v methanol). This indicates
that cells encapsulated in both hydrogel formats exhibited high cytotoxic sensi-
tivities. Most importantly, for each toxin solution, the cytotoxicity response of cells
in the miniaturized hydrogel was not only as uniform as that of cells in the bulk
hydrogel, but also as uniform as that of cells cultured in medium. This reveals that,
after 4 days of encapsulation, cells in the miniaturized hydrogel maintained a high
degree of correlation in cytotoxic sensitivity with the cells in the bulk hydrogel and
as well as in the conventional medium culture.
A comparative investigation on the performance of the PMBV/PVA hydrogel in
a miniaturized format and in a bulk format was performed. Aspects of hydrogel
formation were studied, i.e., cell encapsulation, long-term cell viability, and cell
cytotoxicity. Cell encapsulations in the miniaturized hydrogel and in the bulk
hydrogel were prepared in a glass microfluidic chip and in a standard 96-well
microplate, respectively. The high viability of the cells in the miniaturized hydrogel
was maintained, as in the bulk hydrogel, after long-term (4 days and 8 days)
encapsulation. Remarkably, not only did the cells in both hydrogel formats exhibit
high cytotoxic sensitivities against different toxins with different cytotoxicity after
4 days of encapsulation, but also the cells in the miniaturized hydrogel maintained a
Fig. 18 Cytotoxic response
of L929 cells after 4 days of
encapsulation in miniaturized
PMBV/PVA hydrogel formed
in a microfluidic chip and in
bulk PMBV/PVA hydrogel
formed in a 96-well
microplate
