Small intestinal submucosa as a tunica albuginea graft material.
OBJECTIVE
We evaluated the morphological, immunological and functional response to small intestinal submucosa grafting of the tunica albuginea to determine its potential as a grafting material for penile surgery.


METHODS
Male New Zealand White rabbits underwent a sham procedure (6) or tunical excision and grafting with small intestinal submucosa (6). The erectile response to the intracavernous vasoactive agents sodium nitroprusside plus a papaverine, phentolamine and prostaglandin E1 combination (Sigma Chemical Co., St. Louis, Missouri) was evaluated 45-day postoperatively. The area under the graft was evaluated for stromal collagen and smooth muscle content by Masson's trichrome stain. Protein expression of smooth muscle specific alpha-actin and the inflammatory markers inducible nitric oxide synthase (NOS) and transforming growth factor-beta1 (TGF-beta1) was evaluated by immunohistochemical methods. Total RNA was extracted from the corpora cavernosum underlying the small intestinal submucosa graft and reverse transcriptase-polymerase chain reaction (RT-PCR) was done using an Access system (Promega, Madison, Wisconsin) with gene specific primers for inducible NOS, TGF-beta1 and vascular endothelial growth factor (VEGF).


RESULTS
Grafting of the tunica albuginea with small intestinal submucosa had no significant effect on the magnitude or duration of the erectile response to intracavernous vasoactive agents. Histological examination demonstrated no inflammatory changes in the tunica albuginea or corporeal tissue underlying the area of the small intestinal submucosa graft and there was no appreciable alteration in smooth muscle or collagen content. The 2 groups showed intense positive immunostaining to alpha-actin. Weak expression of TGF-beta1 predominantly associated with smooth muscle fibers was identified in the 2 groups of rabbits by immunostaining and RT-PCR. No significant inducible NOS was detected by immunostaining or RT-PCR in either group. Strong VEGF expression was observed in grafted rabbits. The most noticeable (3-fold) increase in expression was detected in splice variant 165.


CONCLUSIONS
Small intestinal submucosa grafting of the tunica albuginea preserves the duration and magnitude of the erectile response to vasoactive agents. This type of tunical grafting does not stimulate a significant inflammatory response, or cause corporeal fibrosis or loss of cavernous smooth muscle content. Stimulating VEGF may facilitate wound healing and the maintenance of normal erectile function.
Monga
Manoj
M
Department of Urologic Surgery, University of Minnesota, Minneapolis, Minnesota, USA.
Cosgrove
Danny
D
Zupkas
Paul
P
Jain
Amita
A
Kasyan
Armen
A
Wilkes
Nathan
N
Rajasekaran
Mahadevan
M
D000199:Actins / Q000032:analysis; D000527:Alprostadil / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000637:transplantation*; D007421:Intestine, Small; D008297:Male; D009130:Muscle, Smooth / Q000737:chemistry; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000032:analysis; D052247:Nitric Oxide Synthase Type II; D009599:Nitroprusside / Q000494:pharmacology; D010208:Papaverine / Q000494:pharmacology; D010410:Penile Erection / Q000187:drug effects; D010411:Penile Induration / Q000601:surgery; D010413:Penis / Q000737:chemistry / Q000601:surgery*; D010646:Phentolamine / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D011817:Rabbits; D016212:Transforming Growth Factor beta / Q000032:analysis / Q000235:genetics; D014665:Vasodilator Agents / Q000494:pharmacology
D000199:Actins; D020030:Nitric Oxide Donors; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D014665:Vasodilator Agents; D009599:Nitroprusside; D010208:Papaverine; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D000527:Alprostadil; D010646:Phentolamine