Introduction - Microsurgery: Advances, Simulations, and Applications - page 35

1.3.4.5 Membranous microfluidic device (MeME process)
Ikeuchi et al. reported a great breakthrough to achieve membranous
microchannel [104]. They developed a multi-layer hybrid scaffold
consisting of artiicial capillary networks and cell-containing
hydrogels for tissue engineering. In earlier techniques to fabricate
porous scaffolds, compatible achievement of cell accommodation and
microvascular networks was dificult. Especially in soft lithography,
cells have been accommodated in microvascular networks. Because
the volume of microchannel is very small, 3D mass cultures of cells
and tissue reconstruction were very dificult. Also, the space for cell
accommodation and nutrient supply had to be the same. According
to their membrane micro embossing (MeME) process, the space for
cell accommodation and nutrient supply can be separate. Nutrients
were supplied through membranous microchannel while cells were
cultured with hydrogel in the interspaces between each membrane.
In addition, this process contains no concern for cell toxicity because
no organic solvent was used in the polymer fabrication. Heat-
pressing and sealing methods were used to achieve membranous
microluidic device.

1.3.5 Cell Sheet Engineering

Okano and Yamato et al. proposed a novel tissue engineering
methodology layering cell sheets to construct 3D functional
tissues without any artiicial scaffolds [105]. Conluent cells on
temperature-responsive culture surfaces can be harvested as a
viable contiguous cell sheet only by lowering temperature without
any enzymatic digestions. When cells are cultured conluently, they
connect to each other via cell-to-cell junction proteins and. With
enzymatic digestions, these proteins are disrupted and each cell is
released separately. In the case of using PIPAAm-grafted surfaces,
cell-to-cell connections are not disrupted and cells are harvested as
a contiguous cell sheet by decreasing temperature. Furthermore,
adhesive proteins underneath cell sheets are also maintained and
they play a desirable role as an adhesive agent in transferring cell
sheets onto other culture materials or other cell sheets [106]. These
viable cell sheets are composed of cells and biological ECM without
any artiicial scaffolds. Various types of cell sheets have been
successfully lifted up and transferred on other surfaces [107-114].