Who knows where a nose grows? Here’s a curious case. An 18-year-old woman sustained a spinal cord injury that left her legs paralyzed. Three years later, stem cells from her nose were transplanted into the injury site. She developed back pain eight years afterwards, and imaging revealed a mass at the implantation site. The 3-centimeter-long spinal cord mass was mostly nasal tissue and contained large amounts of thick, mucus-like material.

Although the growth wasn’t cancerous, these findings demonstrate just how important safety monitoring is after stem cell treatments and how it should be maintained for years. The team that removed the growth, led by Brian Dlouhy from the University of Iowa, published the surgery results in Journal of Neurosurgery: Spine earlier this month.

The olfactory stem cells were implanted into her spine with the goal of having them develop into neural cells to help repair nerve damage, New Scientist explains. It didn’t work, and even though the unusual growth contained bits of bone and tiny nerve branches, they didn’t connect with the spinal nerves.

"It is sobering," says Harvard’s George Daley, who wasn’t involved with the study. "It speaks directly to how primitive our state of knowledge is about how cells integrate and divide and expand."

This is the first report of a human spinal cord mass complicating spinal cord cell transplantation and neural stem cell therapy.

The unnamed woman was treated at the Hospital de Egas Moniz in Lisbon, where the team received approval for early-stage trials to explore the potential of nasal cells in treating paralysis, New Scientist reports. In 2010, the Lisbon team reported results from a pilot study where 20 patients with spinal cord injuries received implants of “olfactory mucosal autografts,” small pieces of the nasal lining. All the patients survived, and it seemed movement in several of them had improved.

Image: Kurtis Garbutt via Flickr CC BY 2.0