July 10, 2020

The Niche

Knoepfler lab stem cell blog

Several more reports of spinal tumors from nasal stem cell transplants

At least four cases of spinal tumors have now been reported following experimental nasal stem cell transplants for paralysis.

There’s some risk of tumor development with just about any stem cell transplant, but risks are higher with experimental injections of unproven stem cells. Whill risks of tumor formation come along even with standard bone marrow and whole organ transplants (both extremely low), there’s a lot more data in those contexts to understand these tiny risks. With unproven stem cell transplants things are often much murkier and riskier. Update: note that the nasal tissue/cell transplant in some of these cases may or may not have contained stem cells. It’s unclear.

Woodworth, et al. Figure 1 spinal tumor imaging after nasal stem cell transplant. CMAJ 2019.
Woodworth, et al. Figure 1 spinal tumor imaging after nasal stem cell transplant. CMAJ 2019.

In the relatively newly reported cases of olfactory stem cell-related tumors, things are only now coming into focus. A worry is that the tumors often develop many years after injections making them hard to track. I’ve written before about how nasal transplants can lead to tumors such as this past case.

A new case report describes a spinal tumor in a 38-year-old patient with paralysis. The paper entitled “Intramedullary cervical spinal mass after stem cell transplantation using an olfactory mucosal cell autograft” is from authors Claire F. WoodworthGregory JenkinsJane Barron and Nanette Hache. In this case a patient developed a nasal-like tumor a dozen years after getting an olfactory mucosal stem cell transplant. You can see in a screenshot from Figure 1 above that there’s an odd area (the tumor) right in the middle of the spinal cord (more clearly apparent in panels A and C). Look for the two parallel bright “lines” vertically which are interrupted roughly in the middle (on the vertical axis) by the heterogeneous mass in A.

Woodworth, et al. do a nice job of putting this tumor in context of previous reports of similar tumors in other patients who also have nasal stem cell transplants. It’s unclear if these transplants have much upside for potential benefit so the tumor risk in my view makes it inadvisable to continue this type of research without some serious contemplation of how to make it safer first. The paper leaves things unclear as to the patient’s prognosis. It concludes:

“Given the vulnerability of patients who are chronically ill, especially those with spinal cord injury or neurologic disorders who may be targets of Internet-based marketing for stem cell therapy), physicians in Canada should be aware of the rationale behind stem cell therapy as well as the reported adverse events. Both family physicians and specialists may need to counsel patients on stem cell transplantation or diagnose complications in those who have had these procedures.”

Overall, this report also highlights how transplants of adult stem cells are not by definition safe or free from risk of tumors, contrary to some myths out there.

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