Biomedical Engineering Reference
In-Depth Information
Chapter 13
Tissue Engineering: Regenerative Medicine
13.1
It Has Been Described Before!
The Greek poet Hesiod (Eighth century B.C.) has given us, in his Theogony, exam-
ples of interesting cross-breeding creatures, such as the Lernea Hydra, which was
born as the third offspring of Echidna and Typhon. This Hydra was multiheaded and
had the capacity of
immediate
regeneration of a severed head. Actually, according
to the story, in the place of one cut head the regeneration produced two (a siamese
analog?), and Heracles had to ask the help of Iolaos to stop the regeneration process
by denaturing the biological molecules (severed necks) through the application of
heat (Fig.
13.1
).
Another, very prophetic, example of regeneration, described in the same text
more than 2700 years ago, is presented as a mode of punishment: that of Prometheus
being chained on a mountain rock and an eagle eating his liver every day, while it
had to be regenerated within 24 h so that it could be eaten up again, and so on.
Prometheus was punished by Dias, the king of gods in this way, because he had
stolen the fire from Olympus and had given it to the mortal people. Nevertheless, it
was again Heracles who saved Prometheus from his perpetual martyrdom.
Almost everyone is aware, and many people all over the world have observed
that in various species of salamanders, after a limb is cut off, regeneration of that
limb takes place. Recent studies have further revealed that a salamander can regen-
erate limbs, tail, jaws, ocular tissues, intestine and parts of the heart [
402
]. The
mechanisms responsible for this great versatility in the regenerative ability of the
blastemas of salamanders are under intense investigation, and in general, the regen-
erative properties of salamanders have been identified as autonomy, scaling, and
plasticity.
1
The regenerative ability of salamanders, and of other animal species, such as
fish, echinoderms, etc. is currently under intense investigation, as, apart from its
intrinsic interest in understanding the process at the molecular level, it may offer
1
Blastema is a mass of undifferentiated cells, such as the mound of mesenchymal stem cells at the
end of a limb stump, capable of growth and regeneration into an organized structure.
