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Blood transfusions could protect stroke patients from brain damage, mouse trial shows 

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)

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)

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.

THE CAUSES OF STROKE

There are two kinds of stroke: 

1. ISCHEMIC 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.

2. HEMORRHAGIC STROKE 

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.

RISK FACTORS

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.

SYMPTOMS OF 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

OUTCOMES 

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. 

TREATMENT 

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

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