Scientists restore mobility and touch in stroke-afflicted rats

New hope for stroke patients as scientists find way to restore mobility and touch using human stem cells to recreate nerve connections in damaged rat brain

  • Experts transplanted reprogrammed stem cells into the cerebral cortex of rats
  • They found that the new cells recreate lost nerve connections in the brain
  • In six months, the procedure had reversed the damage that followed strokes
  • However, the team caution that a similar treatment for human patients is far off

Scientists have found a way to restore mobility and touch in rats after a stroke using human stem cells to recreate nerve connections in damaged brains — offering patients a new hope.

The study — conducted on rats — showed that the new cells could repair the damage caused by a stroke within six months of being transplanted into the brain.

However, the researchers caution that there is much work to be done before the procedure can be considered suitable and safe to try in human patients.

Strokes are life-threatening and occur when there is either a blockage in or the bursting of a blood vessel, which cuts off blood supply to parts of the brain. 

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The study — conducted on rats — showed that the new cells could repair the damage caused by a stroke within six months of being transplanted into the brain. Pictured, transplanted cells send their nerve fibres across to the other side of the brain in a stroke-affected rat

‘It is remarkable to find that it is actually possible to repair a stroke-damaged brain and recreate nerve connections that have been lost,’ said paper author and neurologist Olle Lindvall of Sweden’s Lund University. 

‘The study kindles hope that in the future it could be possible to replace dead nerve cells with new healthy nerve cells also in stroke patients.’

However, he added, ‘there is a long way to go before achieving that.’

Previous studies by Professor Lindvall and his colleagues had shown that it was possible to transplant nerve cells — derived from human stem cells that had been reprogrammed — into the brains of rate afflicted by stroke.

The transplants are made into each rats’ cerebral cortex — the part of the brain which is most commonly damaged following a stroke.

It had been unclear, however, whether such a procedure would allow the transplanted cells to form connections in the rat brain in the correct fashion to restore normal movement and feeling.

‘We have used tracking techniques, electron microscopy and other methods — such as light — to switch off activity in the transplanted cells, as a way to show that they really have connected correctly in the damaged nerve circuits,’ said Zaal Kokaia.

‘We have been able to see that the fibres from the transplanted cells have grown to the other side of the brain, the side where we did not transplant any cells, and created connections,’ the Lund University neurologist added.

‘No previous study has shown this.’  

With their initial study complete, the team are now exploring the effects of the transplant procedure in more detail. 

‘We want to know more about how the transplanted cells affect the opposite hemisphere of the brain,’ said Professor Kokaia.

‘We also want to take a closer look at how a transplant affects intellectual functions such as memory.’

‘In addition, we will study possible side effects. Safety is, of course, extremely important for cell transplantation if it is going to be used clinically in the future.’

The full findings of the study were published in the journal Proceedings of the National Academy of Sciences.


There are two kinds of stroke: 


An ischemic stroke – which accounts for 80 percent of strokes – occurs when there is a blockage in a blood vessel that prevents blood from reaching part of the brain.


The more rare, a hemorrhagic stroke, occurs when a blood vessel bursts, flooding part of the brain with too much blood while depriving other areas of adequate blood supply.

It can be the result of an AVM, or arteriovenous malformation (an abnormal cluster of blood vessels), in the brain.

Thirty percent of subarachnoid hemorrhage sufferers die before reaching the hospital. A further 25 percent die within 24 hours. And 40 percent of survivors die within a week.


Age, high blood pressure, smoking, obesity, sedentary lifestyle, diabetes, atrial fibrillation, family history, and history of a previous stroke or TIA are all risk factors for having a stroke.


  • Sudden numbness or weakness of the face, arm or leg, especially on one side of the body
  • Sudden confusion, trouble speaking or understanding
  • Sudden trouble seeing or blurred vision in one or both eyes
  • Sudden trouble walking, dizziness, loss of balance or coordination
  • Sudden severe headache with no known cause


Of the roughly three out of four people who survive a stroke, many will have life-long disabilities.

This includes difficulty walking, communicating, eating, and completing everyday tasks or chores. 


Both are potentially fatal, and patients require surgery or a drug called tPA (tissue plasminogen activator) within three hours to save them.

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