Figure 9. Potential future treatment options for erectile dysfunction.

Current treatments provide temporary symptomatic relief, but do not interfere with the progress of the disease itself. The first-line treatment of phosphodiesterase type 5 (PDE5) inhibition depends on bioavailable nitric oxide (NO) to exert any effect. Accordingly, future pharmacological therapies will need to be efficacious in patients who do not respond to PDE5 inhibition (thereby providing treatment to men with neurogenic erectile dysfunction) and provide temporary relief or ‘erections on demand’. The site of action may be the central nervous system (CNS), or a variety of peripheral pathways that control the balance between vasoconstriction and vasorelaxation. By contrast, the aim of regenerative medicine is definitive symptomatic relief (cure) by reversing or halting the progression of degeneration in erectile dysfunction. Regenerative medicine intends to change the course of the disease and in many instances will regenerate failing cells, tissues or whole organ systems. Depending on the severity of tissue damage or the severity of the clinical presentation, various tools, such as growth factors, gene transfer, (stem) cells and tissue engineering could be used to achieve this goal. eNOS, endothelial nitric oxide synthase; Maxi-K channel, calcium-activated potassium channels; ROCK, RHO-associated protein kinase.