Establishment of a Cavernous Fibrosis Model in a Rat Using Adenovirus Expressing Transforming Growth Factor-beta1

Ryu, Ji Kan; Oh, Seung Min; Jin, Hai Rong; Kim, Do Kyung; Kang, Yong Jin; Jang, Jin Hyuk; Suh, Jun Kyu

Abstract

PURPOSE
Transforming growth factor-beta1 (TGF-beta1) has been implicated in cavernous fibrosis due to a variety of causes of erectile dysfunction (ED), such as diabetes mellitus and post-radical prostatectomy. To examine the role of the TGF-beta signaling pathway in cavernous fibrosis, we established a rat model of cavernous fibrosis by using adenovirus expressing TGF-beta1 (ad-TGF-beta1).
MATERIALS AND METHODS
Four-month-old male Sprague-Dawley rats received intracavernous injection of ad-TGF-beta1 (1x10(8), 1x10(9), or 1x10(10) virus particles [vp] in 100 microliter of PBS) and the penis was harvested for histologic examination at 10, 20, or 30 days after injection (n=4 per group and per time point). Based on the initial findings, the animals were divided into three groups (n=6 per group): Group 1, age-matched control; Group 2, intracavernous injection of ad-LacZ (1x10(10) vp/100 microliter); and Group 3, intracavernous injection of ad-TGF-beta1 (1x10(10) vp/100 microliter). At 30 days after injection, erectile function was evaluated during electrical stimulation of the cavernous nerve. The penis was then harvested and stained with Masson's trichrome and antibody to smooth muscle alpha-actin.
RESULTS
Masson's trichrome staining revealed that intracavernous delivery of ad-TGF-beta1 sufficiently induced cavernous fibrosis in a dose-dependent manner. The fibrotic scars persisted up to 30 days after injection at the highest dosage (1x10(10) vp/100 microliter), whereas no histologic evidence of cavernous fibrosis was found in the control rats or the ad-LacZ-injected rats. The rats receiving ad-TGF-beta1 showed a higher cavernous collagen content and less smooth muscle content than the control rats or ad-LacZ-injected rats. Erectile function was significantly decreased in rats receiving ad-TGF-beta1 compared with that in controls or rats receiving ad-LacZ.
CONCLUSIONS
This model induced by ad-TGF-beta1 may play an important role in understanding the pathophysiologic mechanisms of cavernous fibrosis-associated TGF-beta signaling and the development of new therapeutics targeting this pathway.