(CNN) Stem cells have the potential to divide and develop into many different cell types in the body. They are so enchanting and so promising -- they may help paralyzed patients regain use of their limbs or help the nearly blind to see -- that they have Food and Drug Administration officials scratching their heads.
Officials are mulling regulations to address how stem cells are used in various medical and cosmetic procedures, to avoid any exploitation of and harm to patients, and they have asked for input from the public.
The FDA hosted a public hearing at the National Institutes of Health campus in Bethesda, Maryland, last week to discuss draft documents relating to the regulation of human cells (PDF).
Doctors, business owners, academics and patients spoke at the two-day event and weighed in on what they think needs to change. The public can submit comments to the FDA online or in the mail by September 27.
Some are pleading for the FDA to establish merciful regulation so that sick patients can have better access to regenerative medicine. They believe stem cell therapies can help.
Others are calling for the FDA to crack down on clinics, especially those that are marketing unproven stem cell treatments. They believe some stem cell therapies can harm.
How are stem cell therapies currently regulated? The FDA has approved only one stem cell therapy product: a therapy called Hemacord that can restore low blood counts in patients with certain blood disorders.
"Stem cells, like other medical products that are intended to treat, cure or prevent disease, generally require FDA approval before they can be marketed. FDA has not approved any stem cell-based products for use, other than cord blood-derived hematopoietic progenitor cells (blood forming stem cells) for certain indications," according to the administration's website.
Nonetheless, 570 stem cell clinics have emerged across the country, offering stem cell interventions that are not approved in the United States or don't fit within the FDA's regulations, according to a paper published in the journal Cell Stem Cell in June.
The researchers manually conducted an Internet search and analysis to count the number of American-based clinics.
"I was surprised by the huge scope of this industry. I would have predicted half or fewer the number of clinics we found. I was also struck by the coast-to-coast extent of this industry," said Paul Knoepfler, professor of cell biology and human anatomy at the University of California, Davis School of Medicine and a co-author of the paper.
"To date, regulators such as the FDA have not taken significant action on stem cell clinics in the United States, and it is not clear why. As a result, the clinics and those considering opening new clinics view the lack of action as a green light for them to proceed," he said.
Though the researchers discovered hundreds of clinics, Knoepfler said that the FDA seems to have issued only one warning letter to a clinic in recent years. That letter was sent to the Irvine Stem Cell Treatment Center in December.
"Which seems wildly out of proportion with the scope of the stem cell clinic industry," he said. "At the state level, we haven't seen state medical boards take actions as well, which also contributes to the problem."
However, a wave of new studies in recent years has revealed the enticing potential of stem cell therapies, prompting some doctors and patients alike to cross their fingers that the FDA institutes more lenient and less sweeping rules.
"There are a lot of people interested in using stem cells to try to repair orthopedic problems, shooting them in the joints in the knees to try and regrow bone and cartilage. That's been around for a while. There are lots of folks trying to use stem cells in more research settings to regrow spinal cord; there are clinical trials going on of that," said Dr. Arthur Caplan, a professor and founding head of the division of bioethics at New York University Langone Medical Center, who wasn't involved in the FDA hearing.
"Stem cells have been used to regrow gums in dentistry. Stem cells are used in cosmetic surgery. People use them to grow fat tissue when they're trying to reconstruct, usually for breast augmentation," he added. "You'll see stem cell advertisements all around."
What really turns heads, however, is how some stem cell therapies have shown promise in repairing the damage caused by various diseases, such as eye diseases that cause blindness, neurodegenerative diseases such as amyotrophic lateral sclerosis and immune-mediated diseases such as multiple sclerosis.
As such therapies are not available in the United States, some patients have accessed them elsewhere.
It was an overseas experimental stem cell therapy that gave Sara Hughes, 24, new hope for her future -- and the future of the nearly 300,000 other patients who have been diagnosed with the same rare type of juvenile arthritis as she.
Last week, Hughes spoke at the FDA's hearing along with her mother, Fiona Cunningham. The last time they were at the National Institutes of Health campus, a few years ago, Hughes' body was an 83-pound skeletal frame crippled by constant pain.
She was diagnosed with systemic juvenile idiopathic arthritis at 11 months old and became so sick in her adolescence that she was evaluated, treated and studied at the NIH in collaboration with her doctors from the University of Texas Health Science Center at Houston. Hughes could barely walk, was bed-bound and in agony, and spent most of her life hospitalized. She thought fleetingly about the future because she didn't think she had one.
"If not for the help of high-dose autologous mesenchymal stem cell therapy, I would not be here today," Hughes said in her speech at the hearing, adding that she is now "in fairly good health" to share her testimony.
In 2014, Hughes had her own healthy stem cells cultured at Celltex Therapeutics, a FDA-regulated biotechnology company in Houston. Once infused back into her, such cells could help strengthen her body and normalize her immune system, which was overactive due to her autoimmune disease.
However, to have the healthy cells introduced back into her body to treat her arthritis symptoms, Hughes had to travel to Mexico. The procedure was not approved in the United States, where her "own stem cells are considered to be a drug," she said.
Each of her infusions had approximately 200 million stem cells in them -- and Hughes has received about 22 infusions over almost two years, said her mother.
"I was running out of time, but I was willing to put my life at risk to get on an airplane. My quality of life had become so dismal, even one small improvement from my own stem cells would have been enough for me," Hughes said in her speech.
"What happened in the days, weeks and years following my first infusion has changed my outlook. It's hard to believe, in my sick body, I had a wealth of healthy adult stem cells with the ability to so significantly improve my quality of life," she said. "It's sad knowing the people who could benefit most from adult stem cell therapy are probably too sick to get on an airplane. ... We can do better than this."
As some people are hoping for tolerant regulation, others are calling for the FDA to take a stricter approach to stem cell therapies.
The FDA is seeking comment from all of them before official rules are established.
"To be clear, what the hearing is about is feedback on guidelines that are being proposed by the FDA, and these are not binding regulations; they are just points to consider," said Dr. Insoo Hyun, associate professor of bioethics at the Case Western Reserve University School of Medicine, who did not attend the hearing.
"Officially, what the regulations say is that any time a doctor puts a patient's own stem cells back into that patient for therapy, it has to essentially be a medical bedside service. It can't be the transfer of a product that needs FDA regulation," he said. "The cells must be put back into the patient's body, where they will perform the same basic functions as before."
A stem cell transplant can pose many -- and potentially fatal -- risks of complication, from infections to organ damage. A patient who underwent a stem cell therapy in Florida several years ago died during the procedure, according to state authorities.
Knoepfler said he hopes that the FDA will quickly move forward to "more appropriately" regulate the stem cell industry.
"There are a number of relevant regulations that apply to stem cells. When stem cell products are significantly changed or used in a manner not consistent with their tissue of origin, the stem cells are defined as drugs and need to be approved by the FDA before they are put into patients, who are often paying tens of thousands of dollars a pop for these unproven offerings," he said.
At the hearing, there was community-wide frustration in the air from both sides, said Rosario Isasi, research assistant professor in the University of Miami School of Medicine's department of human genetics, who attended the hearing and other FDA meetings this week.
Most experts agree that the current regulatory system needs to change, but opinions on what that change should been polarizing, Isasi said of the hearing.
"I think this polarization of views and interests is eroding the spirit of cooperation that has largely united the regenerative medicine community during the past two decades. This erosion of the community is an issue often missing in the debate."
The frustration was in response to three key issues, she said: the slowness of the FDA to translate how clinical therapies and regenerative medicine products may be regulated, the absence of clarity on how certain products and therapies are defined in such regulation, and the time and expense to obtain regulatory approval.
Obtaining FDA approval is a long process, said Hyun, the Case Western Reserve University School of Medicine professor who did not participate in the hearing.
"FDA approval comes after a series of clinical trials. So in the first phase, you want to look for safety, and then in the second phase, with a larger number of patients, you look for efficacy and whether the therapy works compared to other options, and in the third phase, it's on a grander scale with more patients," he said. "After phase three, if the data prove it's safe and efficacious, the FDA approves it to enter the marketplace."
While it's important for the FDA to focus on "rogue clinics" that are promoting unproven stem cell interventions, Isasi said, doing so shouldn't overshadow the current FDA-approved stem cell clinical trials that are underway.
Her colleague Dr. Joshua Hare, director of the Interdisciplinary Stem Cell Institute at the University of Miami Health System, who attended the FDA hearing, agrees.
"Many doctors are trying to pursue the rigorous pathway and conduct the serious clinical trials with actual stem cells 'to move this field forward,' " Hare said. "This, however, is very expensive and takes a very long time. This is why Congress is looking at ways to accelerate this. We favor a quicker pathway. We do not support cutting any corners that would compromise safety. We think there is a reasonable middle ground."
The discussions the FDA and scientific community are having about stem cell therapies are somewhat similar to the discussions that have been had about the supplement industry, said Caplan, the stem cell expert at New York University Langone Medical Center.
"You might say, in a weird way, all of the supplement industry is like this. That is to say, the FDA didn't regulate it. It grew into a gigantic industry of tens of billions of dollars. No one's really sure what the hell works. Nobody knows what's actually in most of the products, but people take them and use them and have all sorts of testimonials that they'll fix everything," he said. "So we've seen a dangerous explosion in that area. I'd say that's somewhat like stem cells now."
Now that the issues surrounding stem cell clinics are being discussed, Hyun said hopes that doctors and patients alike -- on both sides of issues -- can better understand each other.
"I hope what emerges out of these discussions is much greater clarity about what the concerns are on either side and a more realistic view about where the state of stem cell research is," Hyun said. "One thing that many people have also realized is that the idea of stem cell therapy is very exciting to many people, and it gives many people hope, but it also provides the opportunity to exploit patients."
Isasi said it's crucial to recognize that reasonable differences of opinion exist in order to move forward with establishing new regulation, which is the FDA's end goal.
"I think that common goal remains: promoting medical innovation to serve the needs of patients and the public's health in an ethically responsible manner," she said.