Involvement of Growth Factors in the Process of Post-Vasectomy Micro-Recanalization

Abstract

We investigated the role of growth factors in the process of post-vasectomy micro-recanalization using real-time polymerase chain reaction, enzyme-linked immunosorbent assay and histopathological analyses of the vasectomy sites and controls at different time points in a rat model. Unilateral vasectomies were performed in 18 rats with sham surgery on the contralateral side. Vasectomy sites and vas segments of similar length from the sham operated sides were taken for analysis at 2, 8 and 12 weeks. Real-time polymerase chain reaction was used to test the expression of mRNA of 7 common growth factors and select growth factor receptors. Enzyme-linked immunosorbent assay was performed for growth factors with strong positive polymerase chain reaction findings. Histopathological examination was performed by a staff pathologist (BRD) to detect micro-recanalization, defined as tubules visible on hematoxylin and eosin staining with an epithelial lining of cuboidal or columnar cells. Micro-canals were found in 2 of 18 rat specimens. Real-time polymerase chain reaction of all specimens demonstrated a 12-fold increase in platelet-derived growth factor-beta, a 6-fold increase in platelet-derived growth factor-beta receptor, an 11-fold increase in platelet-derived growth factor-alpha, a 7-fold increase in platelet-derived growth factor-alpha receptor and a 9-fold increase in transforming growth factor-beta compared to the sham operated side. All increases were sustained and statistically significant (p <0.05). Enzyme-linked immunosorbent assay revealed statistically significantly increased expression of platelet-derived growth factor-beta protein. The demonstrated micro-recanalization and sustained growth factor up-regulation at vasectomy sites suggest a possible mechanism for post-vasectomy ejaculate sperm identification. There is a need for further research on the potential role of select growth factors in reconstruction of the male reproductive tract.