I’ve written numerous times about veterinary stem cell therapies, and I’ve been quite critical about the proliferation of such interventions in veterinary medicine. This is not because I don’t see great hope in stem cell therapies, for I do. But to be clear, I’ll repeat what I’ve said before on the subject:
One of the hottest, most fashionable new therapies for a wide range of ailments in veterinary patients is stem cell therapy. There is extensive theoretical and laboratory work in animals and humans to indicate a variety of effects of these cells, and there is good reason to believe that clinical benefits may be possible. Unfortunately, there is no agreement about what these cells do in living animals and how they do it, and there is very little clinical research evidence to support any one of the many different commercial stem cell therapies marketed for dogs and cats. Leading researching in human and veterinary stem cell therapies caution that our knowledge about these cells and what they do is too preliminary to justify claims that they are safe or effective in real patients. I am hopeful that safe and effective stem cell therapies will one day be available, but so far none have proven themselves and using them is still a gamble.
Most media coverage of stem cell therapies is unfailingly positive, and the difficulties of developing and validating a complex set of entirely new therapeutic practices are generally glossed over. So I was pleased to see some mention of these challenges and uncertainties in a recent article at Philly.com. As usual, the notes of caution come from stem cell researchers themselves, who certainly cannot be viewed as an ignorant or reflexively negative source on the subject. The reality is that the very scientists who will hopefully one day bring us revolutionary new therapies based on stem cells are those who see most clearly that commercial stem cell therapies currently marketed are insufficiently understood and not yet proven safe and effective to a reasonable standard.
The article tells the story of Bernie, a pit bull abandoned on a hot roof who suffered severe burns to his paw pads. The veterinarian who treated him was concerned the burns would not heal with conventional wound therapy, so he obtained a compassionate use dispensation from the FDA to try a stem cell therapy not licensed for use in dogs and marketed by Celavet, Inc, a company apparently run by one of the veterinarian’s clients. According to the company, the cells it markets are taken from fetal dogs and cats but have some of the properties of embryonic stem cells, which should enable them to grow into mature cells of any type, including skin. Bernie’s wounds healed, and the case was lauded as an example of a miraculous recovery credited to stem cell therapy.
Of course, I have discussed many times why anecdotes about individual patients aren’t reliable evidence of the safety or efficacy of a particular treatment. In the Philly.com article, researchers from the University of Pennsylvania discusses why this story should not be taken as proof of the usefulness of this therapy.
The stem cells may not have been necessary for Bernie’s recovery, said John Gearhart, director of the University of Pennsylvania’s Institute of Regenerative Medicine and one of the first to isolate human embryonic stem cells.
From examining the company’s literature and pictures of the dog’s paws, he concluded that the new skin was unlikely to have been made from the stem cells. The cells may have helped to produce a protective covering, but Bernie’s paws in the after pictures are most likely covered in his own skin.
“Ultimately, was this animal helped or harmed?” Gearhart asked. “That’s the key question.”
Penn dermatology professor George Costarelis had the same skeptical reaction to the images before and after treatment. In the before pictures, he noted that the dog still had some skin around the wounds and this might have been capable of slowly growing slowly over the injured site.
The stem cells may have covered the wound temporarily, Costarelis said, but he agreed that they probably had been rejected and replaced with the dog’s own skin.
“I’m skeptical this is any different from what would have happened if the dog had good wound care” without stem cells. With no controlled studies, he said, it’s impossible to know.
Such sensible caveats are seldom found in mainstream media coverage of cases like this, and are never mentioned in the advertising materials that promote veterinary stem cell therapies. So while the use of this experimental therapy may be appropriate in such desperate circumstances, the outcome should not be used to fan the flames of public enthusiasm for as yet unproven stem cell treatments. As Dr. Gearhart put it,
The publicity surrounding stem cells has made the public “nuts,” he said. Desperate people contact him all the time, the most emotional of whom are seeking treatments for their animals. “There’s a long history, from the animal side of things,” he said, “of clinics popping up that take advantage of folks.”
He also points out that Celavet did not profit from the use of its product for Bernie, so one cannot criticize the motives of the company. But heartwarming stories like this are the core marketing tool for all unproven and outright bogus medical therapies, and even though they are ultimately unreliable, they are emotionally very compelling. It is up to scientists like Gearhart and Costarelis, and to us as veterinarians, to point out that stories like this do not justify widespread sale or use of such therapies before they have met appropriate standards of scientific scrutiny. Ultimately, the risks of bypassing proper study are greater than the potential benefits.