A paraplegic woman in the USA has developed a growth of nasal tissue in her back eight years after failed stem cell therapy.
Surgeons at the University of Iowa Hospitals and Clinics removed the benign three-centimetre-long growth that was causing the anonymous 28-year-old woman pain, and published the results in the Journal of Neurosurgery: Spine. The removed growth consisted mainly of nasal tissue, including bits of bone and nerve branches that had not connected with spinal nerves. Further, it secreted 'a thick copious mucus-like material', according to neurosurgeon Dr Brian Dlouhy, who removed the growth.
Although rare cases of stem cell treatments causing growths have been recorded before, this seems to be the first one carried out at a Western hospital as part of an approved clinical trial.
'It is sobering', Professor George Daley from Harvard Stem Cell Institute told New Scientist. He added: 'It speaks directly to how primitive our state of knowledge is about how cells integrate and divide and expand'.
The early-stage trials were run by a team at the Hospital de Egas Moniz in Lisbon, Portugal to explore the potential of nasal cells in treating paralysis. In this case, the woman had olfactory stem cells implanted in her spine eight years ago, in hope that they would develop into neural cells and help repair the nerve damage in her spine.
Tissue at the top of the nasal passages contains both olfactory stem cells and olfactory ensheathing cells, which support and guide the growth of the neurons. Olfactory ensheathing cells are often used in spinal cord therapy trials, while olfactory stem cells have the ability to take on the characteristics of other cells in the body because they are partially made up of progenitor cells.
Dr Jean Peduzzi-Nelson, a stem cell researcher at Wayne State University in Michigan, advised the team who conducted the surgical technique, which had previously been tested on rodents. She told New Scientist: 'I am saddened to learn of this adverse event, however, the incidence of this problem is less than one percent'. She added that 'many patients receiving this treatment have had remarkable recovery'.
In 2010, the researchers in Lisbon published their results using this method on 20 people paralysed at various locations in their spine. They found that eleven patients experienced some recovery of movement or sensation, one person's paralysis got worse, whilst one developed meningitis, and four others experienced minor adverse events. However, it is unclear whether the woman from the USA was part of this trial.