Erectile Dysfunction & Its Incidence

Erectile dysfunction (ED) refers to the inability to achieve or to maintain an erection that is satisfactory for sexual intercourse.  This is a common condition that increases in prevalence with aging. Overall, it is estimated that 30 million Americans have ED (1). According to one study, 39% of men at age 40 experience ED, whereas by age 70 the incidence rises to 67% (2). In older patients, 50-85% of ED cases are associated with high blood pressure, diabetes, and cardiovascular disease.  Many other lifestyle factors and medical conditions can also be associated with ED (3).

What Causes Erectile Dysfunction?

The penis consists of paired chambers of spongy tissue (called the corpus cavernosa) that are filled with blood vessels (arteries and veins). The paired chambers are surrounded by smooth muscle that can relax or contract, thereby controlling the blood supply to the penis and whether an erection occurs.

In response to an arousing stimulus, nerve impulses from the central nervous system signal for the smooth muscles along the penile chambers to relax, allowing the arteries to dilate and fill with blood. As the arteries swell and the blood supply to the spongy tissue of the penis increases, the penis expands in size and becomes erect. Due to increased pressure in the penis, the veins become compressed and closed off, trapping the blood that has entered and maintaining the erection.

When sexual arousal stops, smooth muscles in the penis contract to stop blood inflow through the arteries. At the same time, the veins open up to permit blood outflow and the erection ceases.

Many psychological and physical factors can impair a man’s ability to achieve or maintain an erection. For example, nerve damage can prevent signals from being relayed to the smooth muscles or atherosclerosis (hardening and narrowing of the arteries) may impair the ability of blood to enter the penis via the arteries. However, the majority of cases of erectile function in men of all ages are caused by “venous leakage” where reduced smooth muscle mass in the penis allows the blood to escape, leading to “soft” erections or rapid loss of erections (4,5).  Thus, a healthy vascular system is essential for maintaining proper erectile function.  Therapies that can restore and maintain the blood supply are therefore desirable.

Current Treatments For Erectile Dysfunction

The most commonly prescribed treatments for ED are phosphodiesterase (PDE5) inhibitors, which are drugs that are taken orally to increase the ability to achieve and sustain erections.  These drugs, which include Viagra®, Levitra®, Cialis®, and Stendra®, work by relaxing smooth muscles in the penis so that blood flow inflow is increased, resulting in an erection.  While oral medications can be effective at improving sexual function, 30-35% of patients are still unable to achieve an erection (6,7). Numerous medical factors can contribute to ineffectiveness of PDE5 inhibitors including cardiovascular conditions, nerve damage, hormonal deficiencies, psychological factors, and interference by other medications, such as anti-depressants. In addition, some patients experience side effects of taking PDE5 inhibitors, including headaches, flushing or ingestion, as well as rare, serious cardiovascular side effects.

In cases where other oral medications are ineffective, other treatment options for ED are more invasive and include injections of vasodilators into the penis, vacuum pumps, penile prostheses, and vascular surgery. The majority of these treatments do not allow for spontaneous natural erections to occur. Injections administered to achieve erections “on demand” as well as pumps that are placed externally over the penis, can be difficult for men to use. Penile prostheses (surgical implants) are irreversible and can cause penile deformity. The rate of success of vascular surgery is highly variable.  There is clearly a need for additional treatments for addressing ED.

Why Choose the CaverStem® Method For Treating Erectile Dysfunction?

The CaverStem® procedure for treating ED uses cells from the patient’s own bone marrow, the body’s own natural source of stem cells, which are injected into the penis. Treatment with stem cell therapy is performed to restore the individual’s ability to have natural erections. For men who do not benefit satisfactorily from using Viagra® or other first-line oral medications, stem cell therapy can revive erectile function and allow the individual to avoid second-line treatment options that are unnatural, invasive or irreversible.

Stem cells have healing properties to promote the growth and repair of damaged tissue throughout the body. Delivery of a concentrated source of stem cells directly into the penis allows for the full healing potential of these cells to be realized. Research has shown that stem cell therapy for treating ED can safely and effectively restore the areas of the tissue that absent or damaged, including smooth muscle, blood vessels, and nerves (8, 9).


  1. Nunes KP et al. New Insights into Hypertension-Associated Erectile Dysfunction. Curr Opin Nephrol Hypertens 2012; 21(2): 163-70.
  2. Feldman HA et al. Impotence and its medical and psychosocial correlates: results of the Massachusetts Male Aging Study. J Urol 1994; 151: 54–61.
  3. Aversa A et al. Erectile dysfunction: expectations beyond phosphodiesterase type 5 inhibition. J Endocrinol Invest, 2004. 27(2): 192-206.
  4. Rajfer J et al. Prevalence of corporeal venous leakage in impotent men. J Urol. 1988;140:69–71.
  5. Clavijo RI et al. Erectile dysfunction and essential hypertension: the same aging-related disorder? Rev Urol 2014; 16(4): 167-71.
  6. Padma-Nathan H et al. Efficacy and safety of oral sildenafil in the treatment of erectile dysfunction: a double-blind, placebo-controlled study of 329 patients. Sildenafil Study Group. Int J Clin Pract 1998; 52: 375-379.
  7. Goldstein I et al. Oral sildenafil in the treatment of erectile dysfunction. Sildenafil Study Group. New Engl J Med 1998; 338: 1397-1404.
  8. Albersen M et al. Stem cell therapy for erectile dysfunction. Arab J Urol 2013;11(3): 237-44.
  9. Soebadi MA et al. Advances in stem cell research for the treatment of male sexual dysfunctions. Curr Opin Urol 2016; 26(2): 129-39.