The effect of penile urethral fat graft application on urethral angiogenesis

Abstract

Background: Autologous fat grafts are rich in adipose-derived stem cells, providing optimal soft-tissue replacement and significant quantities of angiogenic growth factor. Although fat grafts (FG) are used in several clinical conditions, the use of FG in urethral repairs and the effects of FG to urethral repairs have not yet been reported.

Objective: An experimental study was performed to evaluate the effect of FG on urethral angiogenesis and tissue growth factor (GF) levels.

Study design: Sixteen Wistar albino, adult, male rats were allocated into two groups: the control group (CG) (n = 8) and the experiment group (EG) (n = 8). After anesthetization of all rats, 3-mm vertical incisions were made on the urethras, and then sutured with interrupted 5/0 vicryl sutures. The operations were performed under a stereo dissecting microscope under magnification (×20). In the CG, no additional procedure was performed. In the EG after the same surgical procedure, 1 mm(3) FG was removed from the inguinal region by sharp dissection with a knife. The grafts were trimmed to 1 × 1 mm dimensions on millimeter paper. The FGs were placed on the repaired urethras. The skin was then closed. Samples from urethral and penile skin were taken 21 days after surgery in both groups. Density and intensity of staining with vascular-endothelial GF (VEGF), VEGF-receptor, and endothelial-GF receptor (EGFR) in the endothelial and mesenchymal cells of the penile urethral vessels were immunohistochemically evaluated. Data obtained from immunohistochemical evaluations were analyzed with SPSS 15.0. The P-values lower than 0.05 were considered as significant.

Results: Density of VEGF staining was significantly decreased in the vascular endothelium of the EG compared to the CG (P < 0.05). Density of the EGFR staining was significantly decreased in the vascular endothelium of the EG compared to the CG (P < 0.05) (Table). Intensity of VEGF, VEGF-R and EGFR staining was not significantly different between the two groups. There were no significant differences between groups regarding to VEGFR staining and mesenchymal examination.

Discussion: Decreased density was found in the VEGF staining in the vascular endothelium. This could be explained by the day that the tissues were harvested or because autologous fat grafts might cause decreased growth factor levels, which is contrary to the literature data.

Conclusion: Fat grafting has an immunohistochemical effect on the growth factor levels that are related to angiogenesis after urethral repair. It is difficult to make a firm conclusion about the role of fat grafting on urethral healing. Therefore, future studies are needed to see if FG can be used as an alternative to other procedures in order to avoid complications.

Keywords: Angiogenesis; Fat graft; Hypospadias; Urethra.