DYNAMIC CELL CULTURE METHODS FOR FUNCTIONALIZED BIOMATERIALS - Biologically-Responsive Hybrid Biomaterials - page 398

The concentration, distance, and method of functionalization are all
important factors when incorporating a biomolecule on a scaffold's surface.
Furthermore, these characteristics multiply when more than one biomolecule are
introduced. However, just as the native ECM contains many components, it is
possible that a variety of biomolecules or bioactive motifs should be immobilized
to the material. Moreover, it is concentration gradients which instruct developing
organs, and they can also be used to create complex engineered tissues and tissue
interfaces [152].
It is possible that in the future bioreactors could also be adapted to combine
stimuli to culture hybrid grafts of tissue interfaces. In this way, the organization
of the neotissue may more closely resemble the anatomical interface. For
example, to create an osteochondral graft consisting of both bony and
cartilaginous portions, one cell type could be used: mesenchymal stem cells.
Then, the tissue-specific stimulation could cause regions of the construct to grow
in apposition to one another. Tissue-specific growth factors would also need to
be incorporated, necessitating a complex bioreactor with capabilities for multiple
stimuli [153, 154].
Finally, for tissue engineering to become clinically applicable,
manufacturing techniques need to be scaled up to accommodate a sterile, rapidly
accessible product. This will also involve close communication between
bioengineers and the surgeons who perform implantations of the engineered
grafts. It should be noted that in many instances, the grafts will be patient
specific, whether with cells, composition, size, or shape making the development
of industrial-scale processes a challenge that is currently in progress.
The continuation of research incorporating synergistically both chemical and
mechanical stimuli by combining functionalized materials with dynamic cell
culture systems can only bring us closer to the realization of fully functional
engineered grafts. As our understanding of the consequences of each stimulus
grows, so can our understanding of how stimuli act in concert to shorten the time
of generating an engineered tissue graft.
References
[1] Langer, R. and Vacanti J. P., "Tissue Engineering," Science , Vol. 260, No. 5110, 1993, pp.
920-6.
[2] Bonassar, L. J. and Vacanti C. A., "Tissue Engineering: The First Decade and Beyond," J
Cell Biochem Suppl , Vol. 30-31, No. 1998, pp. 297-303.
[3] Hench, L. L. and Polak J. M., "Third-Generation Biomedical Materials," Science , Vol. 295,
No. 5557, 2002, pp. 1014-7.