Brian J Dlouhy (Department of Neurosurgery, University of Iowa Hospital and Clinics, Iowa City, USA) and others report in the Journal of Neurosurgery: Spine the case of a patient who developed a spinal cord mass eight years after undergoing cell transplantation to treat a spinal cord injury. Based on their observations from the case, Dlouhy et al state that patients who undergo cell transplantation procedures should be monitored for many years.
Dlouhy et al write that there are safety concerns over the use of human stem cells and cell transplantation to treat spinal cord injuries, commenting: “Most concerning is whether de novo tumours can develop from transplanted stem cells or supporting cells.” They add that olfactory mucosal cells have been used as experimental strategies to treat spinal cord injuries, but state that their long-term efficacy and safety is not clear.
In their report, the authors detail the case of a female with an American Spinal Injury Association (ASIA) impairment scale grade A spinal cord injury with sensory level at T-11 and no motor strength in the lower extremities. Three years after sustaining the injury, Dlouhy et al state, the patient sought experimental therapies and underwent “intraspinal olfactory mucosal cell transplantation at the site of spinal cord injury” at institution different from that of the authors’. Eight years after the transplant, she presented at the authors’ institution complaining of progressively worsening mid/low back pain of one year’s duration but with no improvement in her spinal cord injury. After imaging revealed a 3.9×1.2cm intramedually mass at the level of the injury, the patient underwent surgery for diagnosis and resection of the mass.
Dlouhy et al comment: “Histological examination with H&E revealed multiple cysts lined by respiratory mucosa with underlying submucosal glands, some containing globlet cells.” They add the intraoperative finding of thick “copious mucus-like material” within the cysts suggested that these glands “maintained secretory function after transplantation”. The authors also found some evidence that there were newly developing nerve fibres (identified as “nerve twigs”) within the mass, which would indicate the capacity of olfactory mucosa to support nerve fibre regeneration or new nerve formation. However, they write: “Given the lack of clinical improvement in the patient, the functional capacity of these nerve twigs was clinically insignificant.”
According to Dlouhy et al, there is still a need to understand how to control cell proliferation, survival, migration, and differentiation in the pathological environment to “foresee or prevent uncontrolled or abnormal cell growth” in patients undergoing cell transplantation for neurological conditions. They conclude: “Given the prolonged time to presentation [seen in the case report], safety monitoring of all patients treated with cell transplantation and neural stem cell implantation should be maintained for many years.”
Robert Heary (Department of Neurological Surgery, Rutgers New Jersey Medical School, Newark, USA) writes in an accompanying editorial that patients with spinal cord injury are some of the “most vulnerable people on the planet” and spinal specialists “need to watch out for them and assure that they are being cared for properly.” He explains that people with spinal cord injury are “desperate for any potential cure”, which puts them at risk to agreeing to treatments prior to proof of efficacy being demonstrated. He concludes that Dlouhy et al’s case report shows the need for formal follow-up and reporting of long-term outcomes of patients who undergo experimental therapies.
Dlouhy told Spinal News International: “Stem cell therapy and cell transplantation holds great promise; however, we must continue to further our understanding of the very basics of stem cells. Stem cell therapy in animal models of disease will be crucial. But even then, what happens when these cells are transplanted in humans is still a question.”