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Thoughts on the Regenerative Medicine Movement

You can’t open up social media these days without seeing something about “regenerative medicine.” It really is an exciting corner of the medical world with tons of potential but even more uncertainty. Lots of body parts are being injected, shocked, or lasered with the hopes of turning back the clock on the aging process. Skin, joints, hair follicles—even the penis. The goal is often stimulating regrowth of blood vessels and nerves that have withered and failed with age. Platelet-rich plasma, stem cells, exosomes and a slew of other relatively investigational approaches are employed by a number of integrative health clinics. But the key word here is investigational.

Now, investigational does not mean bad. In most cases, there is legitimate theoretical benefit – a reasonable scientific theory for mechanism of action. There are scientific reasons to think that they could work. In contrast, there is truly scant real clinical evidence of efficacy for many of these approaches. Someday, there will be adequate proof (a word that I don’t love in science) for or against many of these approaches. But just not yet. For now, it is truly buyer beware. It is the doctor’s job to make buyers aware.

The good news is that there is probably no significant physical risk for most of these approaches. That being said, we really don’t ever know long-term risks until we have long-term follow-ups. The bad news is that there is often significant financial risk, as many of these are expensive and not covered by insurance. Both physical risk and financial risk should be considered, and weighed against the evidence for benefit that is available. Additionally, if a patient has bothersome symptoms (such as erectile dysfunction) that have not responded to proven conventional therapies, he may be willing to accept the risks and go for a Hail Mary with an investigational strategy.

What is not okay is when doctors or other providers provide unrealistic and unsubstantiated promises about expensive regenerative approaches in order to make money. Not okay. Platelet-rich plasma (the P-shot) is an example. The approach makes sense theoretically, but there is no strong evidence that it actually works for erectile dysfunction (ED) or penis size, as is often presented on clinic websites. Certainly, when patients have exhausted other options it is always reasonable to allow them access to investigational approaches such as this, as long as they truly understand the potential risks (physical and financial) and the available efficacy data (or lack thereof). Meaning, they accept the risk-benefit profile. This is really what medicine should be about. Educating patients honestly and allowing them to make decisions about their bodies and pocketbooks. For one patient, paying $1000 for anecdotal chance of improvement is a no-brainer, whereas others would only do so if there was much stronger evidence.

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As a urologist, I am particularly interested in regenerative approaches for erectile dysfunction. At The Men’s Center, we offer focused linear shockwave as a treatment for vasculogenic ED. There is promising clinical evidence (prospective, randomized, double-blinded placebo-controlled trials) that it is a safe and effective treatment for vasculogenic ED. In fact, at this point it is the only therapy for ED with clinical data supporting the ability to treat the underlying cause of vasculogenic ED, by stimulating regrowth of blood supply to the penis. However, as with any treatment, it doesn’t work for every guy. Twenty to 40% of men do not note significantly improved erection. I have had a few real disappointments but lots of legitimate successes. And the treatment is not cheap. I therefore spend a long time discussing all of these elements with every patient who is leaning towards shockwave. Along the lines of buyer beware, there is no prospective data supporting radial acoustic wave therapy, a therapy often lumped in with *focused linear shockwave and marketed as a treatment for ED. Worse, providers using radial acoustic wave technology rarely make patients aware of the distinction. (*At The Men’s Center, we offer focused linear shockwave–not radial acoustic.)

Most erectile dysfunction is vasculogenic, or related to impairment of blood flow to the penis. This is caused by age, hypertension, high cholesterol, diabetes, and genetics. Vasculogenic ED is caused by cardiovascular disease, the same process that can cause heart attacks and strokes. With regenerative approaches, the hope is that better blood flow can be restored by growth of new blood vessels.
As discussed above, there is promising data for focused linear shockwave therapy (something we offer at The Men’s Center), although it is not yet FDA approved as a treatment for ED. Shockwave has been shown to cause release of growth factors from platelets within the bloodstream as well as the cells lining blood vessels. In clinical trials, the majority of men treated with this type of shockwave experienced greater improvement in erections than those treated with a placebo treatment.

Shockwave aside, what I would like to focus on for the remainder of this blog are injections that have been proposed as potential fountains of youth for the penis – platelet-rich plasma, stem cells, and exosomes.

Platelet-rich plasma (AKA the Priapus shot or P-shot) is commonly employed by providers in sexual health clinics. PRP is essentially a concentrated solution of a patient’s platelets that is the re-injected into the penis. Platelets are loaded with a variety of growth factors that can promote growth of healthy new tissue. For instance, there is data to show that PRP can promote growth of new hair follicles and it is often used to treat male pattern baldness. For erectile dysfunction, PRP is injected into the penis with hopes of improving erections and penis size, and is often advertised as a treatment for ED. A lot of sexual health clinics make a lot of money doing P-shots. Unfortunately, in contrast to hair loss, there is no prospective clinical data that demonstrates clear benefit for ED. Prospective, randomized, double-blinded placebo-controlled trials (the most scientifically valid type of study) looking at PRP for ED have been done. The good news is that the studies did show that PRP for ED is safe. The bad news is that the studies showed that PRP did not appear to be an effective treatment for ED. Now, you may have a friend who swears that the P-shot helped make him a sex machine. This is called anecdotal evidence. It is also a good intro to the placebo effect. Here is some fun data. A study group out of the University of Miami injected a number of ED patients with PRP and an equal number with placebo. No patients knew which of the two they got and the docs didn’t know which they were giving (hence double-blinded). Awesomely, 58% of men injected with PRP reported better erections at 1 month! Sounds like it worked, right? But guess what? The placebo group had the same rate of success. Placebo effect is no joke. This is why anecdotal evidence can be misleading. The conclusion from the Miami study was that PRP works no better than placebo as a treatment for erectile dysfunction.

Like PRP, stem cells are all the craze for treatments of a variety of conditions. Do they help ED? The truth is, we don’t know yet. What are stem cells anyway? Basically, an early embryo is just a cluster of stem cells. Stem cells are the only cells that can become any type of cell they are told to become once they differentiate – into muscle cells, brain cells, nerve cells, blood cells, or skin cells for instance. Cell differentiation during development is truly an amazing and miraculous process. Stem cells can also renew by dividing into more stem cells. The potential therapeutic benefits of stem cells are numerous, but really still in the early stages. Stem cells are also present in umbilical cord blood and tissue, which is why many couples “bank” their kids’ cord blood.

Theoretically, stem cells injected into the penis can become new blood vessel cells or new nerve cells and truly turn back the clock. Some centers, including Wake Forest University where I did my training, are actually growing entire organs from stem cells. There are a lot of sources for obtaining stem cells which are all at slightly different points of the differentiation pathway – these include umbilical cord blood, placental tissue, bone marrow cells, or adipose-derived tissue. There have been some promising pre-clinical studies regarding stem cells for ED, but there are still a lot of gaps to fill regarding which stem cells to use and how much to administer. At this point the data does not indicate any clear safety concerns regarding stem cell treatment for ED. However, I am not aware of any double-blinded, randomized, placebo-controlled trials looking at efficacy of stem cell treatment. This is a topic that I will continue to follow closely.

The last type of regenerative therapy I would like to introduce is exosome treatment. Exosomes are small packets of messenger molecules such as proteins, growth factors, lipids, and nucleic acids surrounded by a small amount of cell membrane. You can think of exosomes as small vesicles that “bud” off of a cell into the extracellular space, and are responsible for cell-to-cell signaling. Exosomes are often advertised for their potential to be superior to PRP, due to greater quantities of growth factors. Exosomes are typically derived from stem cells. Many face creams sold by med spas are said to contain exosomes and touted as a strategy to reduce the signs of aging. Are exosomes the fountain of youth? There is not a lot of data to support the claim that they can predictably and reproducibly slow down the aging process or induce regeneration of aging organs. Is it possible that exosome therapy may be a treatment for erectile dysfunction? Could exosomes actually produce the results that PRP therapy has been advertised to produce despite lack of data? Interestingly, at least one pilot study comparing exosome-type treatment to placebo did show promising results and no adverse side effects, although the study was small and had some design limitations.

So what is the take home message?

I would consider the regenerative therapies for ED to have considerable potential as new modalities. Regenerative medicine is an exciting field with a broad array of possible benefits. These therapies may be able to reverse the underlying pathophysiologic process that cause ED (such as vascular disease or nerve disease) as opposed to just relieving the symptoms (as Cialis and Viagra do). However, further studies are clearly required before we can confidently tout their effectiveness. At this point they really should be considered investigational approaches. Should they be offered to patients? Yes, I think so–but it is certainly not acceptable to make promises or present these therapies as standard of care. I think of it as a balance between risk and benefit, in the context of just how much ED affects a man’s life. Many patients who present to men’s health clinics are very bothered by ED and have tried conventional approaches with disappointing results. These patients may want to consider investigational approaches (but are also easy prey for snake oil salesman). If they are seeking a regenerative strategy, a responsible clinician should discuss potential/theoretical benefit, present any data (or discuss lack thereof) to support use, and discuss risks (both physical and financial). At that point, an informed patient can make the choice.

At The Men’s Center, we want to stay on the very forefront of developments in the sexual health field, such that we can offer our patients the full spectrum of treatments in a conscientious manner.

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