Biomedical Engineering Reference
In-Depth Information
high degree of correlation in cytotoxic sensitivity with the cells in the bulk hydrogel
and as well as with cells in the conventional medium culture. Therefore, the PMBV/
PVA hydrogel behaved as uniformly in the microscale as in the bulk, which is
important, useful, and meaningful for use of the PMBV/PVA hydrogel system in
cell-based applications from a bulk level to a microscale level.
9 Conclusion and Future Perspectives
A spontaneously forming hydrogel composed of MPC polymer with phenyl boronic
acid group and PVA can encapsulate cells under ordinary conditions. The PMBV/
PVA hydrogel dissociates again by addition of sugar, and a cell suspension is
obtained. During this encapsulation-recovery process, cells do not lose their activity
and functions. That is, the PMBV/PVA hydrogel can regulate excessive prolifera-
tion, provide normalized cells with uniform cell cycle phases, and maintain cell-
specific functions when the cells are encapsulated in the hydrogel. In the case of ES
cell encapsulation, the cells maintain their undifferentiated characteristics during
the preservation period in the PMBV/PVA hydrogel. Thus, we conclude that the
PMBV/PVA hydrogel is a novel and powerful soft device for controlling cell
functions in cell engineering fields.
It is usual during differentiation of stem cells for them to form an embryoid body
on suspension culture. However, the cell clusters formed on suspension culture are
aggregations derived from various different cells. Individual cells from the same
tissue may actually differ from each other and have different roles. Furthermore, it
has been recently revealed that the absolute amounts of complementary DNA
expression differ from cell to cell even if the cells derive from the same cell line
[
71
]. Thus, inducing homogeneous cell clusters derived by expansion of single
cells, and not derived by aggregation of various different cells, may maintain high
cell-specific functions and highly efficient differentiation of stem cells.
Acknowledgments The authors appreciate Prof. Madoka Takai, Dr. Ryosuke Matsuno,
Dr. Yuuki Inoue and Prof. Takehiko Kitamori at The University of Tokyo for helpful discussions
during preparation of the manuscript. One of the authors, Dr. Xu Yan, moved to Osaka Prefecture
University, Osaka, Japan in April 2011.
References
1. Lutolf MP, Hubbell JA (2005) Synthetic biomaterials as instructive extracellular micro-
environments for morphogenesis in tissue engineering. Nat Biotechnol 23:47-55
2. Lutolf MP (2009) Spotlight on hydrogels. Nat Mater 8:451-453
3. Lutolf MP (2009) Integration column: artificial ECM: expanding the cell biology toolbox
in 3D. Integr Biol 1:235-241
