By: Dominik Zbogar
This is a summary of a paper by researchers in Poland.
Original article: Pawel Tabakow et al. (2014). Functional regeneration of supraspinal connections in a patient with transected spinal cord following transplantation of bulbar olfactory ensheathing cells with peripheral nerve bridging. Cell Transplantation. 23(12):1631-55. Find the original article here.
Olfactory ensheathing cells (OECs) are found deep in the nose as well as in the olfactory bulb that is part of the brain inside the skull just above the nose. In animal experiments, these cells have been transplanted into the damaged spinal cord and have been claimed to promote the regrowth of severed axons (the ‘wires’ that transmit information from one cell to another) by an English group headed by Dr. G. Raisman. This paper describes the results of OEC transplantation into the spine of one patient with an AIS A injury (this is known as a complete injury where the patient has no measurable sensation or motor function at the lowest part of the spine).
The patient was a 38 year-old man named Darek who was stabbed thirteen months earlier. His spinal cord was incompletely severed at the ninth thoracic level with a 2mm rim of spared tissue, i.e. it was anatomically incomplete. Despite spared tissue, functional testing indicated a “complete” injury by the AIS scoring system.
Before the spinal surgery for OEC transplantation, Darek underwent 8 months of intense (5 hours per day, 5 days per week) physiotherapy consisting mostly of locomotor training. Two weeks before the surgery, one of Darek’s olfactory bulbs was removed from the brain and placed in a cell culture to produce OECs for insertion into the spinal cord. On the day of the spinal surgery, scar tissue was removed, the cells were injected above and below the injury site, and strips of nerve tissue obtained from the ankle were placed in the injury gap to provide a bridge for the OECs to grow over.
There were no complications from the surgery and physiotherapy continued for 21 months. After 4 months, Darek experienced the return of some sensation. At the same time as sensation increased, so too did some voluntary motor function. This occurred mostly in the left leg, the thigh of which also increased in muscle mass. Additionally, Darek experienced increased trunk stability and improved visceral sensation. In all, he improved from An AIS A to an AIS C injury, which means there was sensation and some muscle control below the level of the injury.
Along with these signs of improvement, Darek began to walk with assistance. First, at 6 months with assistance from a physiotherapist, leg braces, and parallel bars, and then at the end of the study, with short leg braces and a walker.
Things to consider:
Interestingly, MRI of the spine performed 19 months following treatment did not show new nerve fibres at the site of the lesion, which indicates that regeneration of tissue was not responsible for Darek’s recovery. At this point it is difficult to state what factors were responsible for Darek’s recovery as the surgery, consisting of spinal cord untethering, resection of scar tissue, injection of OECs into the stumps, and transplantation of peripheral nerve segments into the lesion cavity, as well as intensive physiotherapy, may have played a role in recovery.
What does this mean for people living with SCI?
While this study sounds exciting, it is very important to remember that it involved only one patient. It’s not clear whether his improvement was due to the cell transplantation or other major aspects of the study. Much more research must be done with more patients, and the experimental treatment needs to be validated in a clinical trial before it can be considered a viable clinical treatment.