Increased expression of nestin in the major pelvic ganglion following cavernous nerve injury.

In an effort to identify neuronal repair mechanisms of the major pelvic ganglion (MPG), we evaluated changes in the expression of nestin, an intermediate filament protein and neural stem cell marker following cavernous nerve crush injury (CNI). We utilized two groups of Sprague Dawley rats: (i) sham and (ii) bilateral CNI. Erectile responses to cavernous nerve stimulation (CNS) were determined at 48 h in a subset of rats. The MPG was isolated and removed at 48 h after CNI, and nestin immunolocalization, protein levels and RNA expression were evaluated. At 48 h, erectile responses to CNS in CNI rats were substantially reduced (P<0.05; ∼70% decrease in intracavernous pressure/mean arterial pressure) compared with sham surgery controls. This coincided with a dramatic 10-fold increase (P<0.05) in nestin messenger RNA expression and protein levels in the MPG of rats with CNI. Immunoflourescence microscopy demonstrated that nestin upregulation after CNI occurred within the ganglion cell bodies and nerve fibers of the MPG. In conclusion, CNI induces nestin in the MPG. These data suggest that nestin may be involved in the regenerative process of the cavernous nerve following crush injury.

Stem and endothelial progenitor cells in erection biology.

Erectile dysfunction (ED) is defined as the consistent inability to obtain or maintain an erection for satisfactory sexual relations. The past 20 years of basic science research on erection physiology has been devoted to investigating the pathogenesis of ED and has led to the conclusion that ED is predominately a disease of vascular origin with dramatic changes occurring in the endothelium. Research has also led to an understanding of the biochemical factors and intracellular mechanisms responsible for corporal smooth muscle contraction and relaxation and the influence of endothelium-derived relaxing factors. The development of methods to deliver both stem and endothelial cells to the penis has kindled a keen interest in treating ED with gene- and cell-based therapies. In this paper, erection physiology and stem cell biology is reviewed, and the potential application of novel cell-based therapies for the treatment of ED is discussed.