Last month saw a major medical breakthrough: a man paralyzed
from the chest down is now able to walk with a frame after transplantation of specialized
cells from the nasal cavity into the spinal cord. Darek Fidyka, 38, became paraplegic after being stabbed in the back multiple times 2010. This
resulted in almost complete severing of the spinal cord the injury. In 2012,
team of researchers from Poland and the UK transplanted cells from the
olfactory bulb into the spinal cord of the man at the site of damage. Roughly
two years after the procedure, the patient is able to walk with assistance and
has regained feeling in his lower body. The results were published in Cell Transplantation in October (1).
The procedure takes advantage of the fact that olfactory
nerves, responsible for our ability to smell, continue to regenerate in
adulthood. Nerves from the nose epithelium travel to the olfactory bulb,
located in the base of the brain, which further transmits the smell signal to other
parts of the brain. Specialized cells called olfactory ensheathing cells (OECs)
surround the nerve fibers and support cellular regeneration.
Researchers hypothesized that these cells could help
regenerate other nerve fibers, such as those in the spinal cord.
Transplantation of OECs to damaged spinal cords in mice and rats led to
improvement; however, the procedure had never been done in humans before (2). To
harvest the OECs, part of the patient’s skull was temporarily removed. The
olfactory bulb was then removed from one side and cultured in a petri dish.
Other cells, such as blood vessels, were removed and the OECs and their
accompanying olfactory nerve fibroblasts were allowed to grow for 12 days. The cells
were then injected into the spinal cord stumps and along the rim of the
residual cord with a tiny needle. Nerves from the patient’ leg were grafted to
bridge the 8 mm gap between the spinal cord break.
The first signs of improvement occurred around 4 months
after the transplant with restoration of some sensation in parts of the body
and voluntary muscle contractions at around 5 months. But the road to recovery
was still long with pivotal progress occurring 10 months after the procedure
when Fidyka was able to flex muscles in the legs and muscle mass increased. However, most of the improvement has been to
the left side of his body. As expected, Fidyka initially lost sense of smell on
the side where the olfactory bulb was removed, but surprisingly, he later regained
some sense of smell.
It is unlikely that Fidyka’s ability to walk was due to spontaneous
recovery as several studies have concluded that spontaneous recovery in
paraplegic patients of this type most likely occurs within the first six
months. In contrast Fidyka showed no sign of improvement up to the procedure,
21 months after injury. He had undergone extensive rehabilitation prior to and
after the transplantation.
Fidyka’s drastic improvement indicates the spinal cord was
able, with the help of OECs and the nerve graft, to repair itself. However
researchers stress that this is only one patient and needs to be repeated
before drawing too many conclusions. Additionally, the spinal cord injury was
relatively new and the cord was not completely severed. Still the study
highlights the potential of OECs as a therapy in spinal cord injuries as well
as possibly, in neurodegenerative disorders.
References:
1. Tabakow, P., 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 Transplant. Online
