After dozens of procedures in Europe, a promising therapy for people with SCI crosses the Atlantic
“A stem cell is a cell that has not begun to develop into any specific tissue type, and it really has the potential to become any different type of tissue in the body,” explains Dr. Steven Hinderer, director of the Center for SCI Recovery at the Rehabilitation Institute of Michigan. “In normal human growth and development in a fetus, there are various signals from the environment, in utero, that prompt cells to begin to differentiate into specific tissue types, and it’s even possible outside the uterus and fetus to acquire stem cells.”
Dr. Hinderer is investigating a procedure that entails harvesting cells from one’s own body and implanting them into the spinal cord. The technique, called autografting or stem cell transplantation, was developed by a team in Portugal in July 2002. Forty-one people have had the surgery so far, including one American.
“The surgery involves untethering,” Dr. Hinderer explains, “which means there’s a lot of scarring around the spinal cord after an injury like this, and so the surgeon tries to remove as much scar pressure off of the spinal cord as possible, so that may help some of its cells. Then, the tissue is often harvested from the sinuses, on the underside of the skull.”
Why is this sinus tissue important? “It has a couple of different kinds of cells in it that are helpful. There are cells that are already in different stages of becoming sense of smell, or olfactory nerves. They’re not stem cells, in the true sense. They’ve already begun to become nerves. Nonetheless, they’re not well-developed. The advantage is that, even though their intended path was to become olfactory nerves, they’re not too far down the road of development, and, because they’re in the spinal cord, they can be prompted by that environment to become spinal cord nerves.
“There’s a second type of cell in there that’s a helper cell, and, in addition to supporting the development of the stem cells, they can help with the repair of any surviving spinal cord tissue that’s damaged. There are really a lot of different things happening there at the same time.”
Cells are taken from a person’s own body through a technique referred to as an autograft. “The advantage of using one’s own body tissue is that there’s no chance of rejection,” Dr. Hinderer points out. “As soon as you start using tissue from some other source, there is a risk.”
“There are a lot of folks who have done work in this area, but the person who really brought this to the level that it is now is Dr. Carlos Lima. He is a neuropathologist and neurologist from Portugal who also studies diseases under the microscope, and he spent a lot of years looking at this tissue on slides and in human beings, to see how it changes over time, with age and other tissues. Carlos did some animal studies with transplants into the spinal cord, and he spent thirteen years of work before the first human being had the operation.”
Dr. Lima now works with Dr. Gene Peduzzi, a neuroscientist at Wayne State University in Detroit.
“There’s a lot of work currently being done to learn what the necessary ingredients, or stimuli, are to help cells develop into specific types of tissue that would be helpful for treating various diseases,” Dr. Hinderer says. “One of the things we would like to do is take these cells and grow them in a laboratory. There’s been no one who has gotten the cells to do this. It’s an ongoing process to try to improve and further develop the procedure to get better and better outcomes.”
This is one of the reasons that it is unclear whether embryonic stem cells would be as effective in the procedure as the adult varieties. “We don’t know. We have to know how to get the umbilical stem cells to grow into spinal cord nerve cells, and, currently, we don’t know how to get that done. There are a lot of cells that can be grown, or cultured, but these particular cells from this tissue that are stem cells have not been successfully grown that way. That’s why the procedure is a direct transplant. Pretty much everyone who has had the surgery has experienced some improvement in muscle function below the level of the injury, and at least some sensory return. Whether that results in the ability to perform more functional tasks remains to be seen.” A few patients with spinal cord injury experience recovery of bladder function, as well.
These benefits, however, are not immediate. Recovery from this procedure can take two years, or possibly longer. “The best chance of how this kind of recovery will likely occur is how Mother Nature already does things. The example I use is of a newborn infant. Newborns are helpless, because, even though they have an undamaged brain and spinal cord, the nerves in those areas have not made the necessary connections and they continue to develop. Once they make those connections, they insulate with myelin covering, and they begin to work. That’s why a baby develops over the first two years of life. It takes almost two and a half years, on average, for an infant to develop that nervous system and reach a point where they can walk in an adult pattern.” Since the adult stem cells used in the procedure are so immature, they must go through a similar process. Physical activity is important during recovery, to help the new nerve cells learn their job in the spinal cord.
Erica Nader was the first American to receive such a transplant. “Erica has worked extraordinarily hard. We don’t have a large group of people that we’ve followed yet to know for sure, but in those who have worked as hard, we’ve seen opportunity for important improvement, with a combination of the procedure, hard work in therapy and other treatments.”
“I’m very happy to have had the opportunity to have the surgery and also help make it more accessible to others,” Nader says. “I feel I’ve made gains that otherwise would not have been possible.”
With the manipulation of the spinal cord comes a risk. “Patients could lose neurologic function, compared to what they had. It hasn’t happened to us, but there is a risk.” For this reason, people injured above C-5 are not desirable procedure candidates, as they may wind up on a respirator. Thus, only those with complete injuries are considered. “Patients have a fair amount of pain around the incision, which lasts for a couple of months, getting better over time.” Sinus headaches, nose pain, and a temporary reduction of sense of smell are also common. Because it is experimental, the $45,000 procedure is not currently covered by medical insurance.
“We don’t encourage somebody to do this,” Dr. Hinderer says. “We cannot make the decision for the patient. This is not a cure for SCI; it’s an opportunity to provide better outcomes. Everyone who’s working on the cure agrees that it will be a combination of different treatments coming together that will get the job done.”
Lori A. Wood is a frequent contributor to Orbit.
