人造血液已经问世?

Getting fresh, uncontaminated blood to field medical units and hospitals can mean the difference between life and death. Supplies are not guaranteed and often heavily reliant on voluntary donors.

A mismatch in blood grouping can also prove fatal. Sometimes, it's not just the shortage of blood that is a problem. It's the shortage of safe, uncontaminated blood products that's important.

That's why scientists are trying to find an alternative manufactured blood in the laboratory. Some British scientists are hoping to produce enough red blood cells for their first human trials in the next 12 to eighteen months.

One of them is Professor Mark Turner who is hopeful that his team's work on red blood cells will be a precursor to work on other cell types.

For example, it could lead to the production of heart muscle cells for people who've had heart attacks, or liver cells for people with liver failure. Lessons learned in developing this product could be applicable to other cell therapies. But Turner admits that that's a long way off.

"The cultured blood would have to undergo testing on animals and then a complex series of clinical trials, again to demonstrate its safety and its effectiveness and those do take several years to complete."

Chris Cooper is the Professor of Biochemistry at Britain's University of Essex. He says there are other difficulties to overcome too as trials in other countries have shown.

"There doesn't seem to be a problem in creating a product that will deliver oxygen and stay in the circulation, so that was a big challenge that has been essentially solved, the problem is that it does other things and there are really two other things it can do. One is that it will remove some important molecules in the body one of which is nitrous oxide which is a gas that is important in controlling blood flow and blood pressure in the body, so you're removing a good molecule. The other is that they generally appear to create bad molecules, they're made of iron - so our products are like the normal blood product for carrying oxygen consists of iron it, so it can transport oxygen. At the same time that iron can what's called oxidize, just like iron in your car can rust. And that oxidation can be damaging when that product is outside the safe environment of the red blood cell."

Some scientists believe they've overcome the obstacles at a molecular level in the laboratory. But scaling up production for anything like the quantities needed for transfusion services is a long way off. Cooper says:

"There's a long way to get from the laboratory to the animal trials and the clinical trials. Particular problems of the blood substitutes are you have to make so much of the product that as opposed to a normal pharmaceutical where you have to make a tiny amount in a pill, we have to make an armful, so a huge amount. So there's a big problem in making enough even to start the animal trials and that's the challenge people like me as basic scientists have."

Turner believes trials are about eight years away. In the meantime all the scientists want to remind us all of the importance of donating blood.

For CRI, I am Li Dong.