Biomedical Engineering Reference
In-Depth Information
reconstructive surgery of the skin (Abai
et al
., 2004; Blanco
et al
., 2004),
as well
as patients with chronic skin wounds (Gottlieb and Furman, 2004). By 2004, over
13 000 patients had been treated worldwide with Integra®.
14.7
Regeneration of adult organs other than skin
In addition to skin, confirmed observations of at least partial regeneration using
scaffolds with high biological activity (templates) have been also reported for
the following adult organs: peripheral nerves (Chamberlain
et al
., 1998, 2000;
Zhang and Yannas, 2005; Yannas
et al
., 2007b) and conjunctiva (Hsu
et al
.,
2000). Significant progress in the study of regeneration has been reported inde-
pendently in studies of bone (Mistry and Mikos, 2005), heart valves
(Rabkin-Aikawa
et al
., 2005), articular cartilage (Kinner
et al
., 2005), urological
organs (Atala, 2005) and the spinal cord (Verma and Fawcett, 2005). The reader
is referred to the relevant publications for further details (see also a compilation
in Yannas, 2005a).
14.8
Antagonistic relationship between contraction
and regeneration
There are several lines of qualitative evidence suggesting that contraction blocks
induced regeneration. Data supporting this view will be reviewed briefly below.
An extensive discussion of the data has appeared elsewhere (Yannas, 2001,
2005b).
14.8.1
The early-fetal to late-fetal transition in mammals:
emerging dominance of contraction with loss of
regenerative activity
A developmental transition, occurring during late mammalian gestation, leads
from healing by regeneration without contraction to healing by contraction and
scar formation (Soo
et al
., 2002, 2003; Colwell
et al
., 2005).
14.8.2
Amphibian development: gradual replacement of
regeneration by contraction
During tadpole development (North American bullfrog), contraction gradually
becomes dominant at the expense of regeneration. A small component of scar
formation is first observed only after metamorphosis of the tadpole to the adult frog
has been completed. At the adult stage, regeneration is abolished and contraction
accounts for almost all of closure of the defect (Yannas
et al
., 1996).
