Imagine driving your car along your typical
commute, when suddenly you are in an accident. Waking up in the hospital, you find out that
your spinal cord was damaged. Immediately, everyday tasks like walking,
eating, and taking a shower become huge challenges. Patients with spinal cord injuries can lose
the ability to move their legs and upper extremities and even lose their sense of touch. But that’s not all: these patients often
suffer from pain, ulcers, bowel issues, difficulty breathing, depression and an overall reduced
life expectancy. A team of scientists and clinicians at Asterias
Biotherapeutics is currently conducting a clinical trial in patients with spinal cord
injuries, with the goal of restoring some of the lost motor function and sensation,
and, as a result, improving the quality of these patients’ lives. Before we jump in, let’s understand what
happens in spinal cord injury. The spinal cord is a big bundle of nerves
and supporting cells, including specialized nerve cells called motor neurons, which are
responsible for movement. Nerves connect our brains to our bodies by
carrying sensory and motor signals from the brain, down the spinal cord, and to the muscles
throughout the body.
The information is transmitted across large
distances through a part of the neuron called the axon, which acts like a wire. Axons are protected by a material called myelin,
which you can think of as the insulation around the wire. This insulation helps the nerve signals move
rapidly down the spinal cord to the muscle to allow for movement. When the spinal cord is injured, two things
can happen: 1) the nerve axons can get damaged, blocking the nerves from sending important
motor and sensory signals, and 2) the myelin insulation can also break down, leaving the
nerves exposed and unable to function normally. The Asterias team has begun a human clinical
trial to test a new experimental therapy – called AST-OPC1 – to see if it can be effective in
restoring function back to patients who have suffered severe spinal cord injuries. Because the major damage in these types of
injuries is done to the nerves, and to their protective myelin insulation, the scientists
are tackling this first. Their approach uses a cell type known as oligodendrocyte
progenitor cells (OPCs). These OPCs are made from human embryonic stem
cells, which can become any type of cell in the body.
The stem cell-derived OPCs are introduced
directly into the spinal cord at the site of the injury, where they can help repair
damaged nerves and can produce more myelin in the spinal cord. This therapy is exciting because it utilizes
a type of cell similar to one found naturally in the body, and harnesses its normal function
to reinsulate and repair the nerves damaged in spinal cord injury. With support from the introduced OPCs, damaged
nerves at the sites of injury might recover their functional abilities to conduct motor
and sensory signals between the brain and the hands, arms and fingers—and, hopefully,
reverse some of the devastating paralysis that affects many patients with spinal cord
injuries. By utilizing the latest stem cell based technologies,
scientists are hoping to significantly improve the quality of life of spinal cord injury
patients and restore their ability to interact with the world around them! So far, Asterias’ animal studies, and their
ongoing human clinical trial, have shown promising results: safe implantation of the cells and
as a result increased motor function.
But it is important to remember these results
are early, and this stem cell based therapy must be tested further. With the successes we will celebrate, there
will inevitably also be setbacks and obstacles along the way. However, even setbacks will provide learning
opportunities for further scientific and medical exploration that will bring us closer to curing
or mitigating devastating conditions such as severe spinal cord injury. As we build on the progress enabled by California’s
Proposition 71 and the funding agency it created, the California Institute of Regenerative Medicine,
we must keep the momentum going: we are now at the point of seeing, for the first time,
clinical research results in human patients with devastating conditions such as severe
spinal cord injury, and we can make even more progress as we learn from these ongoing studies. Only with continued support for biomedical
research can we increase our understanding of the therapeutic potential of stem cells
and translate that understanding into meaningful treatments that help give patients their lives
back..