Biomedical Engineering Reference
In-Depth Information
promising candidates in the generation of tissue-engineered liver
constructs and other epithelia
in vitro
and
in vivo
.
The integrated approach to construct a precision-engineered
scaffold for epithelial tissue engineering would find other appli-
cations in lung, esophagus, intestine, pancreas, and kidney tissue
regeneration as well. In the lung, sheets of polymer membrane-
supported cell constructs with fine structural and functional
integrity would be used to seal leakages in the airways to pre-
vent lung collapse due to infection-induced lung damage. In intes-
tineandesophagus,multilayeredconstructswithmultiplecelltypes
are being developed to repair the digestive functions; and kidney
glomeruli or proximal tubules are being reconstructed for eventual
treatment of kidney failure.
Thecellsourceremainsonemajorbottleneckinlivertissueengi-
neering. Due to the instability of adult hepatocytes, hepatic progen-
itors are becoming an alternative. Hepatic progenitors display both
proliferationanddifferentiationcapacity.Afewstudieshavedemon-
strated differentiation and maturation of hepatic progenitors in
PEG hydrogels,
71
macroporous alginate hydrogels,
119
porous PLA
scaffolds,
120
and alginate microspheres.
87
Cell-cell contact seems to
be critical in initiation of polarity and subsequent differentiation
and functionality,
71
,
119
while stronger cell-matrix contact prevents
hepatic differentiation.
119
Because of the bipotential differentiation
capacity of hepatoblasts, both hepatocytes and cholangiocytes can
be derived, which will eventually form the complex liver tissue with
bile duct structure.
87
Soluble factors perform better in 3D porous
PLLA scaffolds.
120
However, scaffolds capable of regulating progen-
itor cell differentiation and maturation are still lacking. With the
detailed understanding of stem cell biology, integration of novel
engineering approaches with stem cell technology is becoming one
major direction in epithelial tissueengineering.
Acknowledgments
Nur Aida Abdul Rahim is a recipient of the Global Enterprise
for Micro-Mechanics and Moledular Medicine (GEM4) postdoctoral
fellowship.
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