Blood transfusions may have the potential to protect patients from brain damage following a stroke, a study on mice has suggested.
Caused by inadequate blood supply reaching parts of the brain — either via a blood clot or burst vessel — strokes often lead to long-term disabilities.
The condition is also one of Britain’s biggest killers — with the more than 100,000 strokes that occur in the UK each year leading to around 38,000 deaths.
Researchers from the US found that mice given induced strokes had reduced symptoms after being given an injection of blood from a healthy peer.
The team believe that the infusion helps lower post-stroke levels of a protein that has the potential to damage brain cells.
Blood replacement is a growing area of interest in medicine — one being explored in the treatment of conditions including COVID-19 and Parkinson’s disease.
Blood transfusions may have the potential to protect patients from brain damage following a stroke, a study on mice has suggested (stock image)
‘Acute stroke causes complex, pathological and systemic responses that have not been treatable by any single medication,’ said paper author and neuroscientist Sophie Ren of the West Virginia University.
‘A novel therapeutic strategy is proposed, where blood replacement robustly reduces damage and improves neurological deficits in mice.’
Among the side-effects of stroke are the risk of the blood-brain barrier breaking down — allowing plasma components of the blood to damage brain cells — along with a harmful systemic reaction that can occur outside of the brain.
In their study, Professor Ren and colleagues demonstrated that blood replacement therapy can minimise this damage by performing tests on 333 male mice, which were give blood injections seven hours after receiving an induced stroke.
The treatment worked by lowering levels of the protein matrix metalloproteinase-9 — or MMP-9, for short — in the mice’s bloodstream, along with inflammatory chemicals and immune cells. Also, it may provide oxygen and other neuro-protective factors.
In a healthy body, MMP-9 is involved in breaking down the so-called ‘extracellular matrix’ that provide structural and biochemical support to cells.
The protein plays a role in normal bodily functions like bone growth, embryonic development and wound healing — but it can also harm grey matter.
‘Levels of MMP-9 in the blood are known to be increased in mice — and humans — in the first few hours after a stroke occurs,’ Professor Ren explained.
The researchers found that the blood infusion resulted in their being less dead tissue as a result of oxygen deficiency — while brain function was also improved.
In contrast, when MMP-9 was artificially added to the blood being injected, the replacement therapy did not work — proving that removing the protein is key.
In their study, Professor Ren and colleagues demonstrated that blood replacement therapy can minimise this damage by performing tests on 333 male mice, which were give blood injections seven hours after receiving an induced stroke (stock image)
‘These findings suggest blood replacement combats inflammation by reducing MMP-9 levels in the blood and brain of mice after a stroke,’ Professor Ren said.
‘Our study is the first to show the therapy leads to profoundly better outcomes that are controlled via MMP-9. It offers new insights into stroke damage mechanisms.’
Stroke remains a major cause of disease and death across the globe, Professor Ren explained — but current treatments for the condition tend to focus on the surgical removal or drug-induced break down of the clots that cause them.
‘However, these methods have limited time windows. In the clinical field of stroke, the mantra is “time is brain”, because damage evolves every minute,’ Prof. Ren said.
‘Currently, blood based therapies are emerging as treatments to combat ageing and fight neurodegenerative diseases,’ Professor Ren continued.
‘The results of this study could lead to a breakthrough in stroke therapy, because this innovative therapeutic strategy may reduce the mortality of stroke patients and improve stroke outcomes.’
‘These results can provide a foundation for the future use of blood replacement therapy in clinical trials for improved treatment of strokes.’
The full findings of the study were published in the journal Nature Communications.