Biomedical Engineering Reference
In-Depth Information
the RWV are rotated at 13 rpm and 37 rpm, respectively. Engineered
cardiac tissues grown in an RWV are found to be structurally and
functionally more superior to those grown in static or spinner flasks
[11]. In this way, an RWV has been studied extensively in the field
of tissue engineering research for improving the efficiency of cell
viability and increasing the differentiation rate of cultured cells by
enhancing the diffusion of nutrients and oxygen [12, 13]. These
results promise to establish new knowledge and a new method for
tissue engineering research.
6e.3
Hollow-Fiber Bioreactor
A hollow fiber is a cellulose-based midair material, and the wall of the
fiber has a thickness
= 180-200 μm, and
a lot of micropores. This fiber is usually used as the main component
of an artificial kidney, and the hollow fiber removes waste products
from and supplies nutrients and oxygen to perfusing blood by its
dialysis function, which is the principle of filtration and diffusion via
micropores. Generally, red and white blood cells, platelets, albumin,
and other complements are unable to pass through the micropores
on a hollow fiber, but smaller-diameter substances can pass through
the membrane by diffusion. A hollow-fiber bioreactor having fibers,
where oxygen and nutrients are allowed to diffuse into cells, is used
in the field of cell culture. A hollow-fiber bioreactor has two spaces
separated by the hollow fiber: cells are cultured outside the hollow
fiber, and the fresh medium is perfused inside the hollow fiber (Fig.
6e.2). This bioreactor can supply enough glucose and amino acids
and remove waste products, including ammonia and lactic acid, from
the medium through the semipermeable wall of the fiber [14-17].
Moreover, growth factors and antibodies produced from cultured
cells can be held outside the fiber. Since a hollow fiber can provide
a stable culture condition, which imitates an adequate in vivo
environment for promoting the proliferation and differentiation
of cells, many scientists use hollow-fiber technology for culturing.
Entcheva et al. seeded cardiac muscle cells into a scaffold that had
a structure similar to a hollow fiber, and after 12-day cultivation,
the hollow-fiber scaffold was found to allow cardiac muscle cells
to grow and make gap junctions, which can pass an electric current
t
= 10-50 μm, a diameter
D
