Biomedical Engineering Reference
In-Depth Information
Figure 9. Microphotographs of cell-enclosing (a-c) unmodified agarose and (d-f) agarose-gelatin
conjugate microcapsules (a, d) immediately after encapsulation, at (b, e) 14 d, and (c, f) 28 d of
cultivation (Bars are 150 μm). Transition of mitochondrial activity of cells enclosed in (■) unmodified
agarose microcapsules and (●) agarose-gelatin conjugate microcapsules. (Data are reproduced with
permission, from Sakai S et al. Biotechnol. Lett. [37] @ 2007 Springer).
Significant low cell adhesiveness and cell proliferation are two features of unmodified
agarose [63]. When transplanting a proliferative cell line
in vivo
, these features are useful for
suppressing an excess proliferation of enclosed cells to avoid the risk of tumorigenesis [64].
However, these features are not advantageous for applications such as the bioproduction of
therapeutic proteins
in vitro
. For enhancing the growth of enclosed cells, we developed
microcapsules from an agarose-gelatin conjugate [37]. The conjugate shows a sol-to-gel
transition, but no gel-to-sol transition, around body temperature, similar to native agarose
[65]. Gelatin is a natural polymer derived from collagen, and has been used for medical
applications such as wound dressings and as scaffolding material for tissue engineering [66-
69]. Gelatin hydrogel is obtained by cooling the aqueous gelatin solution obtained by heating
