Biomedical Engineering Reference
In-Depth Information
technology provides a valuable technique to prolong hepatocyte
functionality and enable more efficient development of liver tissue
engineering methodologies to create liver-targeted regenerative
therapies and a better in vitro model, which is important in pharma-
cological and pharmacokinetical studies.
4b.3.9
Thyroid Cell Sheets for Hypothyroidism
While some patients who undergo surgical excision of endocrine
organs need restoration of their serum hormone levels by
hormonal replacement therapy, there are some limitations to
maintaining the complex homeostatic interactions of hormones
via oral administration. Here again, cell-based therapy and tissue
engineering are believed to provide an alternative physiological
therapy for endocrine disorders. For this purpose, our laboratory has
proposed a novel method using cell sheet-based tissue engineering.
A 3D thyroid cell sheet has been fabricated by using a temperature-
responsive culture dish and rat thyroid gland, and the fabricated cell
sheet has been used for the therapy of a rat hypothyroidism model
after receiving a total thyroidectomy [70]. After transplantation into
the rat models, the thyroid cell sheet graft had sufficient functional
microvessels and tissue became thicker compared with an in vitro
cell sheet. The tissue organizes into honeycomb-like structures of
thyroid follicles, and the inner surface of the follicles is continuously
covered with follicular epithelial cells. These results show that an
implanted thyroid cell sheet graft was reconstructed into the thyroid
tissue, very similar to the native thyroid. While serum levels of free
triiodothyronine (fT[3]) and free thyroxine (fT[4]) significantly
decreased after the total thyroidectomy, transplantation of the
thyroid cell sheet restored thyroid function, and the resulting
improvement was maintained for at least one month. These results
shows that thyroid cell sheets transplanted into a total thyroidectomy
model can reorganize histologically to resemble a typical thyroid
gland and restore thyroid function in vivo, suggesting that cell sheet
transplantation of endocrine organs is suitable for the therapy of
hormonal deficienc y.
4b.4 Conclusion
Various types of cells can be cultured into a biologically functional
cell sheet by using a temperature-responsive culture dish, and 3D
