Three elderly women from Florida were blinded after Bioheart, a private clinic, injected fat cells into their eyeballs in an unregulated clinical trial costing $5,000.

Stem cells have become a modern equivalent of philosopher's stone, promising treatments for aging-related illnesses and potential cure for previously untreatable diseases. But the field of stem cell research is still young, and despite of its potential dangers, is often unregulated.

For the three women, aged 72, 78 and 88, it was a surgery gone wrong. Determined to win against age-related macular degeneration, they joined what they thought was a federally monitored clinical trial. However, their treatment turned out to be unproven and was conducted at a loosely regulated clinic in Florida.

According to a paper published in the New England Journal of Medicine, the three patients visited a private clinic owned by a company named Bioheart, now called U.S. Stem Cell. All the women suffer from age-related macular degeneration and had some visual impairment but could still see well enough to drive.

During their treatment, adipose tissue-derived stem cells, or fat cells, were taken from the patients' stomach using liposuction. After extracting the stem cells, clinic staffs injected it to the patients' eyeballs. After the procedure, the patients were told to avoid any strenuous activities.

The patients were back in the hospital just days after the procedure due to vision loss. Two of the patients lost much of their eyesight, while the other one went completely blind. Authors of the case study associated the vision loss with ocular hypertension, hemorrhagic retinopathy, vitreous hemorrhage, combined traction and rhegmatogenous retinal detachment or lens dislocation.

"There's a lot of hope for stem cells, and these types of clinics appeal to patients desperate for care who hope that stem cells are going to be the answer, but in this case these women participated in a clinical enterprise that was off-the-charts dangerous," said Dr. Thomas Albini, an associate professor of clinical ophthalmology at the University of Miami, in a report from NBC News.

Experts cautioned people about the dangers of unproven treatments and unregulated clinical trials. They noted that not all research posted on were endorsed by the NIH. Furthermore, legitimate clinical trials rarely, if ever, charges patients for their participation.