INVESTIGATIVE UROLOGY

Intracavernosal injection of vascular endothelial growth factor improves erectile function in aged rats
Park K, Ahn KY, Kim MK, Lee SE, Kang TW, Ryu SB
Department of Urology, Chonnam National University Medical School, Donggu, Gwangju, Republic of Korea
Eur Urol. 2004; 46: 403-7

• Objectives: To investigate whether intracavernosal injection of vascular endothelial growth factor (VEGF) can restore erectile function in the aging rat.
• Materials and Methods: Ten young (4-5 months) and 30 old (24 months) Sprague-Dawley male rats were used. The old rats were divided into 3 groups: vehicle-only (phosphate buffered saline plus 0.1% bovine serum albumin; n = 10), VEGF 1 microg/kg (n = 10), and VEGF 10 microg/kg (n = 10). At 2 and 4 weeks after treatment, erectile function and histology were evaluated by hemodynamic study, histomorphometric analysis, and immunohistochemistry.
• Results: After 4 weeks of treatment, the ratio of peak intracavernosal pressure to systemic arterial blood pressure in response to neurostimulation was significantly higher in both the VEGF 1 microg/kg (79.9 +/- 7.7%) and the VEGF 10 microg/kg group (76.8 +/- 5.8%) compared to the vehicle-only group (63.1 +/- 8.5%; p < 0.05). The percentage of cavernosal smooth muscle was significantly higher in the VEGF 10 microg/kg group (16.1 +/- 1.4%) compared to the vehicle-only group (12.8 +/- 2.2%; p = 0.047). VEGF treatment in old rats increased e-NOS and VEGF expression in both treatment groups.
• Conclusion: Intracavernosal injection of VEGF appears to restore smooth muscle integrity and improve erectile function in aged rats.
  
  
• Editorial Comment
  This is an interesting and welcome study in the era of tissue engineering techniques. After old rats treatment as described, the authors elegantly evaluated through hemodynamic study, histomorphometric analysis and immunohistochemistry, whether an intracavernosal injection of VEGF could restore erectile function and whether it was related to trabecular structural changes in aged rats.
  The authors found that intracavernosal injection of VEGF resulted in significant increases in intracavernous pressure in response to neurostimulation after 4 weeks in both VEGF treatment groups. VEGF treatment in old rats increased not only e-NOS and VEGF expression in endothelial lining, but also the percentage of corpus cavernosal smooth muscle. Thus, intracavernosal injection of VEGF improves penile erectile quality in aged rats.

Dr. Francisco J.B. Sampaio
Full-Professor and Chair, Urogenital Research Unit
State University of Rio de Janeiro
Rio de Janeiro, Brazil