Biomedical Engineering Reference
In-Depth Information
leading to restoration of the original organ (regeneration). However, in the adult
mammal, injury to the stroma is typically irreversible and leads to formation of
nonphysiological scar (repair). Every organ in the adult can be irreversibly injured,
resulting in repair with scar formation. In certain organs injury is irreversible when
it leads to damage of specific tissues whereas in others it becomes irreversible when
the injury exceeds a critical size.
A number of theories have been proposed to explain the inability of the adult to
regenerate its organs. Among these scar formation has been frequently cited as the
cause for inhibition of regeneration.
Several approaches have been used to restore the loss of organ function that
results from an extensive acute or chronic repair process in the adult. They include
organ transplantation, autografting, implantation of permanent prostheses, use of
stem cells, in vitro synthesis, and induced regeneration. The topic of this volume,
induced regeneration, is a process in which physiological tissue, rather than scar,
is deliberately synthesized at the anatomical site of the adult host that has been ir-
reversibly injured. This approach is embodied in the collagen scaffold regeneration
paradigm, which is based on five empirical rules and which explains at each of the
scales of tissue, cell and molecule, the mechanism of induced regeneration.
