We're still learning about stem cells and what they can and can't do, so it's unsurprising that there will be a few strange accidents. One such accident happened to a woman who underwent stem cell treatment for paralysis.
Eight years ago, the anonymous woman, a US citizen, was treated at Hospital de Egas Moniz in Lisbon, Portugal, according to New Scientist. Doctors took stem cells from her nose and implanted them into her spine, hoping that the olfactory cells would develop into neural cells to help repair spinal nerve damage.
The operation was part of an early stage clinical trial exploring the potential of nasal cells in treating paralysis. Other researchers usually remove and isolate the cells, cultivating them in the lab before transplanting them, but the Lisbon team skipped this step and transplanted the cells directly.
The cells did grow -- but they remained olfactory cells, and the woman's pain worsened. Last year, surgeons removed a three-centimetre growth of nasal tissue, bone and nerve branches from the site; but it wasn't causing the pain by itself. The tissue was also producing mucus, which was pressing on her spine.
"It is sobering," Harvard Medical School stem cell researcher George Daley. "It speaks directly to how primitive our state of knowledge is about how cells integrate and divide and expand."
The Lisbon team published a paper in 2010 detailing the effects of the trial on 20 patients. Of those 20 -- out of an estimated 140 given the treatment to date -- eleven experienced improvement in their condition, one patient's condition worsened, one developed meningitis, and four others had minor adverse reactions.