There are some pretty freakish, but well-substantiated, reports this week that demonstrate just how much we still have to learn about stem cells and how they work (and don't work).
Eight years ago, a US citizen traveled to Portugal to take part in a trial of a treatment meant to restore function to nerves in her spine. Doctors there injected her with nasal stem cells. This week, doctors removed a benign-but-painful tumor from her back. It was made up mostly of nasal tissue, plus some bone and nerves, and was (here's the really freaky part) secreting mucous.
This is not a case of somebody flying overseas to visit the Portuguese version of The Simpsons Dr. Nick, writes Clare Wilson at New Scientist. Although there are plenty of sketchy doctors, all over the world, who will inject you with stem cells as part of some hand-wavey rejuvenation treatment, this woman was taking part in a legitimate research trial of a technique that had been successful in animals.
The woman at the centre of today's news was treated at the Hospital de Egas Moniz in Lisbon, where a team got approval for early-stage trials to explore the potential of nasal cells in treating paralysis. 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.
Other groups are experimenting with taking such tissue from the nose, growing it in the lab to isolate the desired cells and transplanting them. But the Lisbon clinic was trialling a procedure that bypassed this isolation step. They took small pieces of the nasal lining and directly transplanted them into their patients' spines. That could be why it retained its capacity to make mucus, says Dlouhy.
In 2010, the Lisbon researchers published their results using this method on 20 people paralysed at various locations in their spine. Eleven experienced some recovery of movement or sensation; one person's paralysis got worse, one developed meningitis and four others experienced minor adverse events. It is not clear whether the woman from the US was part of this trial.
This is a reminder that participating in clinical trials isn't a risk-free proposal, writes Paul Knopfler, a stem-cell researcher at the UC Davis School of Medicine. What's more, though, Knopfler says it shines a light on a critical factor in doing stem cell research with human subjects — the follow-up and tracking of patients doesn't go on long enough after the treatment.
... long-term follow up of stem cell treatments is crucial and most of the follow up done by stem cell clinics is too short. Usually follow up outside of academic clinical trials only lasts months. This case of a benign, but harmful tumor showing up eight years after treatment shows that follow up should be measured in decades.