A female patient in the US has grown a nose on her back following a failed experimental stem cell treatment that was intended to cure her paralysis. The nose-like growth, which was producing a “thick mucus-like material,” has recently been removed as it was pressing painfully on her spine. If you ever needed an example of the potential perils of stem cell therapy, and just how little we actually know about the function of stem cells, this is it. It’s also notable that this stem cell therapy was carried out in a developed country, as part of an approved trial (apparently unwanted growths are more common in developing nations with less stringent medical safeguards).

Eight years ago, olfactory stem cells were taken from the patient’s nose and implanted in her spine. The stem cells were meant to turn into nerve cells that would help repair the woman’s spine, curing her of paralysis. Instead, it seems they decided to do what they were originally meant to do and attempt to build a nose. Over a number of years, the nose-like growth eventually became big enough and nosy enough to cause pain and discomfort to the patient. As reported by New Scientist, “surgeons removed a 3-centimetre-long growth, which was found to be mainly nasal tissue, as well as bits of bone and tiny nerve branches that had not connected with the spinal nerves.” [DOI: 10.3171/2014.5.SPINE13992 – “Autograft-derived spinal cord mass following olfactory mucosal cell transplantation in a spinal cord injury patient”]

What went wrong, then? Basically, at the top of your nasal passages there is the olfactory mucosa. This region contains all of the machinery for picking up odors, and the neurons for sending all of that data off to your brain’s olfactory bulb for processing. Cells from this region can be easily and safely harvested, and with the correct processing they behave just like pluripotent embryonic stem cells that can develop into many other cell types. These olfactory stem cells could develop into cartilage, or mucus glands, or neurons. The researchers obviously wanted the latter, to cure the patient’s spinal nerve damage — but seemingly they got it wrong, and thus she sprouted a second nose. Moving forward, newer olfactory stem cell treatments have an “isolation” stage to prevent this kind of thing from happening. [Read: The first 3D-printed human stem cells.]

It’s important to note that medicine, despite being carried out primarily on humans, is still ultimately a scientific endeavor that requires a large amount of trial and error. In the western world, it’s very, very hard to get a stem cell therapy approved for human trials without lots of animal testing. Even then, the therapies are often only used on people who have “nothing to lose.” Obviously it’s hard to stomach news like this, and I’m sure that stem cell critics will be quick to decry the Frankensteinian abomination created by these scientists. But when you think about the alternative — no advanced medicine and significantly reduced lifespans for billions of people — then really, such experimental treatments are nothing to sneeze at.