Biomedical Engineering Reference
In-Depth Information
of oxygen consumption as the study progresses. Bioreactor inputs should be
adjusted to refl ect changes in these parameters. Understanding regenera-
tion phenomena, such as the different signaling pathways stimulated by cell
interactions with ECM, will allow the appropriate scaffold parameters and
reaction rates to be chosen (Maes
et al.
, 2009).
5.7 Future trends
It is imperative to keep in mind that each bioreactor should be tailored
specifi cally to the environment it tries to simulate (Griffi th and Naughton,
2002). Over time, bioreactor designs will improve on their ability to simu-
late a given tissue environment. Future trends in bioreactor development
should focus on automating the culturing process if this form of therapy and
artifi cial organs are to become the future of medicine. The parameters of
bioreactors need to be automatically adjusted to keep the construct grow-
ing and to avoid necrosis. The oxygen requirements change as cells pro-
liferate. Porosity decrease inhibits internal transfer as the volume of the
construct increases; this must be refl ected in nutrient supply as well as in
other parameters.
The future of bioreactor design will be heavily infl uenced by computa-
tional fl uid mechanics. It is to be hoped that future designs will include less
invasive sensors for accurate real-time assessment of the reproduced envi-
ronment. Martin and Vermette (2005) also expect future designs to build
on physiology of the placenta, as 'ideal model reactor'. Future bioreactor
studies might see greater use of nanotechnology and other means of supple-
menting cultures with oxygen. Numerous studies recognize that oxygen dif-
fusion is inadequate as the sole means of oxygen transport. As bioreactors
become more complex they will try to mimic the oxygen delivery system of
red blood cells. However, methods of waste removal from the growing sys-
tem have so far has escaped the attention of most researchers. The bioreac-
tors of the future should be able to better mimic the vascular system found
in tissues that are cultured. There have been some studies that pre-vascu-
larized constructs before implanting them. Although the porous scaffolds
allow for infi ltration of cells and diffusion of nutrients and wastes, they do
not mimic the internal vascular system in the tissue. Tissue engineers must
be able to mimic this micro-vasculature in order to improve mass delivery
in a large tissue construct.
5.8
Conclusion
In summary, signifi cant progress has been made in the development of bio-
reactor- related technologies in recent years. Bioreactors are essential for
cell growth and tissue regeneration in physiologically relevant complex
