Biomedical Engineering Reference
In-Depth Information
construct with a straight configuration as well as a 3D configuration such as the wavy
configuration observed in hydrogels (Figure 14).
Conclusion
In this chapter, we described the methods for the production of cell-enclosing
microcapsules of about 100 μm in diameter, much smaller than conventional microcapsules,
by extruding a cell-suspending aqueous polymer solution from a needle with a diameter of
several hundred micrometers. Droplets of about 100 μm in diameter that subsequently
become microcapsules were obtained via a jetting process in a water-immiscible liquid. The
gelation of the droplets suspended in a water-immiscible liquid was achieved via a thermal
gelation process using agarose and agarose-based materials and an enzyme-catalyzed gelation
process. The size of the microcapsules is too small to encapsulate pancreatic islets, but is
large enough to encapsulate single cells. Studies using such small microcapsules are still at an
early stage in respect of practical applications. However, we believe that these small
microcapsules of about 100 μm diameter will become useful devices in the field of cell
therapy and bioproduction considering the recent advances made in genetic engineering that
enable the use of cells as reactors to produce desired proteins. We also think that
microcapsules, smaller than the maximum allowed size for a tightly packed cell mass that
does not limit the oxygen supply [76], would be a useful tool for the production of spherical
tissues from individual cells.
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