Short-term Morphological and Growth Factor Changes in Rat Bladders Augmented with a Porcine Small Intestinal Submucosa

Byun, Seok Soo; Kim, Joo Heon; Oh, Ji Eun; Kim, Hyeon Hoe; Lee, Eun sik; Lee, Chong wook

Abstract

PURPOSE: This study was performed to investigate the short-term changes in the morphology and growth factors after the augment of rat bladders with a porcine small intestinal submucosa (SIS).
MATERIALS AND METHODS
The experiments were performed in 39 female Sprague- Dawley rats, comprised of 3 controls, 18 sham-operated and 18 SIS-augmented rats. The sham-operated group underwent a primary closure after a longitudinal incision of the bladder. The augmentation cystoplasty was performed using a porcine SIS after a hemi-cystectomy. The rats were postoperatively sacrificed at periods ranging between 12 hours and 14 days, and their bladders procured for histological examination. Reverse transcription-polymerase chain reactions (RT-PCR) were performed to evaluate the expressions of the keratinocyte growth factor (KGF) and the transforming growth factor-alpha (TGF-alpha).
RESULTS
Both groups showed an acute inflammatory reaction during the immediate postoperative period, and chronic inflammatory cells appeared 48 hours postoperatively, with new capillaries and fibroblasts appearing 4 days postoperatively. The disrupted urothelial barrier was restored on the 7th postoperative day in the sham group, and epithelialization began to appear on day 4 in the augmented group. New granulation tissue covered the small intestinal submucosa, like a sheet of membrane, by the 4th postoperative day, and its thickness and cellularity increased with time. The mRNA expressions of the KGF and TGF-alpha increased during the initial postoperative period, but tended to derease with time. Their expressions coincided with acute inflammatory reactions.
CONCLUSIONS
In conclusion, the short-term morphological changes after the augmentation cystoplasty, with a porcine small intestinal submucosa, were initially composed of acute inflammation, chronic inflammation, fibroblast aggregation, neoangiogenesis, epithelialization and formation of granulation tissue. The mRNA expressions of the KGF and TGF-alpha coincided with acute inflammatory reactions.