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INVESTIGATIVE
UROLOGY
Autologous
penile corpora cavernosa replacement using tissue engineering techniques
Kwon TG, Yoo JJ, Atala A
Department of Urology, Children’s Hospital and Harvard Medical School,
Boston, Massachusetts, USA
J Urol. 2002; 168:1754-8
- Purpose:
The availability of engineered tissues would be beneficial to patients
undergoing penile reconstruction. We explored the possibility of replacing
an entire cross-sectional segment of both corporal bodies with autologous
engineered tissues in rabbits, and investigated the structural and functional
integrity of the neo-corpora.
- Materials
and Methods:
Acellular corporal collagen matrices were obtained from donor rabbit
penis. Autologous corpus cavernosal smooth muscle and endothelial cells
were harvested, expanded and seeded on the matrices. An entire cross-sectional
segment of protruding rabbit phallus was excised, leaving the urethra
intact. A total of 26 matrices, including 18 seeded with cells and 8
without cells, were interposed into the excised corporal space. An additional
4 rabbits that did not undergo surgical intervention served as normal
controls. Functional and structural parameters (cavernosography, cavernosometry,
mating behavior and sperm ejaculation) were followed for 6 months. Gross
examination, and histochemical, immunocytochemical and Western blot
analyses were performed at 3 and 6 months after implantation.
- Results:
The
experimental corporal bodies demonstrated intact structural integrity
on cavernosography and decreased maximal intracavernosal pressures on
cavernosometry compared to normal controls. Mating activity in animals
with engineered corpora normalized by 3 months postoperatively. The
presence of sperm was confirmed during mating and was present in all
rabbits with engineered corpora but in only 2 with the matrix alone.
Histologically sinusoidal spaces and walls lined with endothelial and
smooth muscle cells were observed in the engineered grafts. Each cell
type was identified immunocytochemically. Grafts without cells contained
fibrotic tissue and calcifications with sparse corporal elements. Western
blot analysis of engineered grafts showed nitric oxide synthase activity
similar to normal controls.
- Conclusions:
Autologous corpus cavernosal smooth muscle and endothelial cells seeded
on collagen matrices can form corpora cavernosa tissue structures in
a rabbit model. Engineered corpora cavernosa achieved adequate structural
and functional parameters. This technology may be applicable to patients
who require additional tissue for phallic reconstruction.
- Editorial
Comment
The authors replaced in vivo entire cross-sectional segments of corpora
cavernosa in the protruding penis in rabbits by interposing autologous
engineered tissue, and provided encouraging data on erectile function
and structural integrity. The authors should be commended for this wonderful
work that represents a very important step towards the replacement of
human penile tissue.
The authors have used acellular matrices obtained from homologous corpus
cavernosum, seeded with autologous smooth muscle and endothelial cells.
The engineered grafts had sinusoidal structures similar to normal controls,
and were composed of multiple smooth muscle layers surrounding layers
of endothelial cells. The functional evaluation showed that the present
engineered corpora cavernosa may not achieve full erection, but it can
show sufficient erectile activity for penetration and adequate sexual
function.
Phallic reconstruction using conventional methods, such as free flaps
or prosthetic devices, has not been uniformly satisfactory. Thus, a
large number of congenital and acquired abnormalities of the genitalia
would benefit from the availability of transplantable, autologous corpus
cavernosum tissue for reconstructive procedures.
Dr.
E. Alexsandro da Silva
Urogenital Research Unit
State University of Rio de Janeiro
Rio de Janeiro, Brazil
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