Brain cell transplants capable of restoring the failing minds of Alzheimer’s patients are on the horizon, after scientists created mature neurons from stem cells.
Currently little can be done to reverse the damage caused to the brain in patients with dementia, or other neurodegenerative diseases, with families forced to watch their loved ones mentally, and physically, slip away.
But US scientists at Northwestern University have proven it is possible to turn stem cells into neurons, in a breakthrough which they say could allow damaged or lost brain cells to be replaced, potentially restoring cognition.
Neurons could also be transplanted into patients with spinal cord injuries to help bring back nerve sensations.
Previous attempts to create neurons have stalled because the cells remained immature and unable to perform complex signalling, or the branching and electrical activity normally seen in mature brain cells.
“When you have a stem cell that you manage to turn into a neuron, it’s going to be a young neuron,” said Samuel Stupp, a professor of Materials Science, Chemistry, and Medicine at Northwestern University in Chicago.
“But, in order for it to be useful in a therapeutic sense, you need a mature neuron. Otherwise, it is like asking a baby to carry out a function that requires an adult human being.
“Mature neurons are better able to establish the synaptic connections that are fundamental to neuronal function.”
Doctors could convert skin cells into stem cells
To solve the problem, researchers cultured the immature neurons on a tiny mesh containing rapidly moving synthetic signalling molecules – a process which mimics the conditions that surround neurons as they develop over time in the body.
The more rapidly the molecules moved, the more mature the neurons became.
It means that in future, doctors could take skin cells from a patient, convert them into stem cells and then use the technique to create a bank of healthy neurons for transplant into the brain or spinal cord.
The cells would genetically match the patient so there would be no chance of rejection.
The team believes it could provide a promising therapy for spinal cord injuries as well as neurodegenerative diseases, including Alzheimer’s disease, amyotrophic lateral sclerosis (ALS), Parkinson’s disease, or multiple sclerosis.
There are nearly 950,000 people living with dementia in Britain, 145,000 people with Parkinson’s, 130,000 with multiple sclerosis and 5,000 with ALS. But there is currently no way to cure or reverse the conditions.
Breakthrough will allow scientists to study diseases in more detail
The breakthrough will also allow scientists to study those diseases in more detail, as they will now be able to grow very mature diseased brain cells in a dish, and test out new therapies and drugs.
As part of the research, the team took skin cells from a patient with ALS and converted them into stem cells then motor neurons, before ageing them considerably until they started showing signs of the protein build-up which causes the disease.
“For the first time, we have been able to see adult-onset neurological protein aggregation in the stem cell-derived ALS patient motor neurons,” said Northwestern’s Evangelos Kiskinis, the co-corresponding author of the study.
“It’s unclear how the aggregation triggers the disease. It’s what we are hoping to find out for the first time.”
“Cell replacement therapy can be very challenging for a disease like ALS, as transplanted motor neurons in the spinal cord will need to project their long axons to the appropriate muscle sites in the periphery but could be more straightforward for Parkinson’s disease.
“Either way this technology will be transformative.”
‘Well beyond’ current capabilities
However, experts in Britain warned that therapy using stem cells was likely to be a long way off, and could face many challenges.
Commenting on the research, Prof Selina Wray, Alzheimer’s Research UK senior research fellow, said: “Some researchers think that stem cell therapies could one day replace damaged brain cells and restore people to perfect cognitive health but this is well beyond our current capabilities.
“The brain is an extremely complex organ and Alzheimer’s doesn’t just impact one type of nerve cell or a specific region of the brain.
“Each individual nerve cell in the brain can have thousands of connections to other cells. The total number of these connections reaches hundreds of trillions.
“While the prospect of stem cell therapies for Alzheimer’s is tantalising, there are huge challenges to this approach. Even if we were able to promote the growth of new cells that directly replace those damaged by Alzheimer’s – unless we also tackle the disease processes, the newly grown cells would also become damaged.
“So there’s a long road ahead before stem cell based therapies could reach people with disease like Alzheimer’s”
The research was published in the journal Cell Stem Cell.