A pioneering US-Irish collaboration is working towards reversing spinal-cord injuries by using stem cells, writes Dr Claire O'Connell.
A scientist from the US Mayo Clinic has joined with Irish researchers in Galway to pioneer new approaches in spinal cord repair.
Prof Tony Windebank, professor of neurology at the Mayo Clinic College of Medicine in Minnesota, has teamed up with the Regenerative Medicine Institute (Remedi) at NUI Galway to encourage damaged spinal cord tissue to re-grow through structural scaffolds loaded with stem cells.
Nerves relay messages between the brain and the rest of the body. They run through the brain and spinal cord, or central nervous system, then radiate out through a network known as the peripheral nervous system (PNS) to reach other parts of the body.
If nerves in the spinal cord are damaged they do not repair well by themselves, but severed nerve fibres in the PNS can regenerate and get back to doing their job, explains Prof Windebank, who is on a year-long visit to Ireland as a Science Foundation Ireland ETS Walton Fellow at Remedi.
"So what's important is the environment of the damage," he says. "It's not so much what has happened as where it has happened."
Several years ago Windebank had informal, corridor conversations with a colleague in the Mayo Clinic about how to "fool" spinal nerves into thinking they are like the PNS by implanting a temporary scaffold carrying environmental factors to promote re-growth.
This prompted them to develop a cylinder with a series of hollow channels bored lengthways through it. The structure can be implanted into the severed spinal cord to physically bridge the disconnected ends. The hollow channels provide guide tunnels through which nerves can regenerate, then the scaffold biodegrades harmlessly over time
The Mayo Clinic researchers found that in rats the spinal nerves re-grew quite well through the 2-5mm channels in the scaffold, says Windebank.
Next they wanted to improve the biological environment within the scaffold's guide channels to help stimulate better nerve regeneration. One plan was to line the channels with adult stem cells taken from the bone marrow, which have the capability to develop into a number of cell types. This is why Prof Windebank came to Remedi last September. "We were looking to get expertise in adult stem cells and in this field clearly one of the best and most rapidly growing places in the world is Galway," he says.
The team at Remedi are now looking at traumatic spinal cord injury in rats where the bone has literally crashed into the cord and damaged the nerves, explains orthopaedic registrar Dr Cathal Moran, who is working on the project. He says that in humans spinal cord injury is a major clinical problem. "It primarily affects young adults - up to 80 per cent of victims are male and many of them are between 16 and 30."
The Remedi researchers have now implanted the cylindrical scaffolds into damaged spinal cords in the rat and are starting to measure recovery following the surgery, says Moran. They have also grown adult rat stem cells on the scaffolds in the lab and are working on implanting scaffolds plus stem cells into injured spinal tissue.
The amount of regeneration will be a critical measure of success. Of the roughly 10 million nerves that run along the spinal cord, Prof Windebank estimates that around one million are needed to get a return of useful function.
The group also plans to use the scaffold as a platform for other therapies, such as engineering the stem cells on the scaffold to produce biochemical factors to help stimulate nerve growth even further. "Conceptually we feel the scaffold provides a way that you can systematically manipulate the environment and show what it is that really works and then put those things together in combination," he says.
However the researchers stress that it will take time before their approach could be trialled for human treatments. "We see the horizon here as being of the order of 10 years," says Prof Windebank, who is setting up the infrastructure to sustain a long-term collaboration with Remedi for this and other projects. "We have got all the equipment and we have had various exchanges, so everything is in place here to do it."