blood_substitute

Today I will introduce you to the centenary quest for artificial blood. We will go through the reasons why this research is so relevant for the medicine community. We will consider what science could reach up to now and we will analyze where it needs to arrive to get a solution.

A research with ancient roots

First of all I want to bring to your attention, that the quest for artificial blood started in the far 1600 and it still goes on nowadays. 

Only in the USA, there are around 17,000 preventable trauma deaths each year due to untreated hemorrhagic shock, a condition that consists in a large loss of blood that leads to a disfunction of the transport of oxygen throughout the body.That’s why we need an alternative substance to human blood.

During history scientists and doctors tried several substances to replace blood.

Firstly, they tried to inject lamb blood into a 15 years old boy, who survived. They thought they solved the problem, but the fellow tries were a set of failures.

Later on, in the 19th century physicians believed they had an answer: Don’t use blood at all but use cow’s milk. It seemed like the perfect choice since they thought that, once in the body veins, it would have transformed in white blood cells. As you can imagine, the experiment didn’t go as expected and the doctors had to abandon this risky idea.

Finally, they attempted the human blood transfusions, but they didn’t know what it could lead to.

Why are blood transfusions not enough?

Unfortunately, blood transfusions are not easy to do. But before we talk about the problems let’s see what they are and how they are used in medicine.

A blood transfusion is a process used to transfer the blood of a person into the veins of another.  Doctors transfuse blood into patients with different illnesses such as sickle cell disease or thalassemia. And not only, for major injuries that involve a consistent loss of blood, transfusions are often required. 

Since human blood is not always available, a form of artificial blood is necessary to save many lives. Moreover the possibility of transferring blood to one person into another depends on many factors. The blood cells only survive for a relatively short amount of time and, in addition, blood needs to be stored in proper refrigerators to be effective. 

But the biggest issue is that to transfuse blood from one person to another, it’s necessary that the donor’s blood type, determined by the molecules on the surface of red blood cells, is the same as the receiver one. A 0- only can receive from 0- and so on for the other blood types that you can see in this image. In addition some types such as AB- are very rare to find, only 1% of the population has it. 

Blood: not only a liquid

During the first part of this presentation we have talked a lot about blood, a substance that has an extremely large amount of functions. But what is it really made of? Let’s turn our attention to its composition. Blood is composed for the 55% of plasma the liquid part, mostly made of water, it transports nutrients and hormones to all the body cells. The remaining 45% is the addiction of erythrocyte even known as red blood cells, leucocyte or white blood cells and platelets. These last ones are responsible of forming clots to stop the bleeding from a cut.

The white cells, which are part of the body immune system, are divided in many cells, each one of whom recognizes and fights specific germs and viruses off the body. In conclusion, most importantly we have the red blood cells that have the responsibility of carrying the oxygen to every single cell of the organism, to assure the production of energy, through hemoglobin, a protein that binds to the oxygen collected in the lungs. 

An artificial set of necessities

The creation of an artificial type of blood would solve many problems, but it’s way more difficult than expected. There are many aspects to consider. The substitute for human blood needs to be compatible with every blood type, and also needs to be accepted by the organism and have the right consistency to circulate properly in the blood vessels.

It also needs to be suitable for transporting oxygen into the organism. It doesn’t necessarily have to carry hormones and other nutrients, since it should replace real blood only for the time necessary to the bones marrow to create more red blood cells.

Moreover it probably won’t be red, since this color is given by the high percentage of iron present in the red cells of our blood.

Solving issues is saving lives

Creating a valid substitute to human blood would solve the problem of being able to find compatible blood types with the most rare types of blood. It would also enable healthcare professionals to prevent patients from having reactions to the donated blood. 

Another aspect to consider is that, if not previously screened, the donor’s blood could contain pathogens that can bring more damage than benefit, especially in the countries where the sanitary system is not well organized. So an artificial solution would be perfect to avoid such inconveniences.

Another thing to keep in mind is that some people refuse to receive blood transfusions for religious reasons, an artificial blood would solve this problem as well.

Also paramedics in battlefields in need of blood for emergency situations would have a large supply of blood ready to be used at any time.

Have we really come to a solution?

Finally we have come to the crucial point: what researches are being done on this topic? 

There are three major attempts in act at the moment.

Many researchers are cooperating to extract the hemoglobin from the red blood cells of our blood, in order to create hemoglobin based oxygen-carriers. The problem is that the hemoglobin outside of a red blood cell is unstable and breaks down into smaller, toxic compounds that can cause heart attacks or strokes.

The second option that we’ll consider is the mimicking of how other species’ blood transport oxygen. Some bioengineers are trying to make synthetic oxygen-carrying molecules, that would result as less toxic than human hemoglobin to the body thanks to their unique structure.

Last but not least other scientists are trying to create a blood substitute out of perfluorocarbons, chemicals that after being pumped into a person’s veins, dissolve the oxygen from the lungs and carry it to every organ of the body. The only trick is that to work the patient should be breathing air composed by the 100% of oxygen, request that is impossible for our body to satisfy.

We are getting close…

In conclusion we don’t have a solution yet, but the first research is making great steps forward. In fact a researcher called Allan Doctor , from the Washington University of St. Louis, had the brilliant idea of coating the extracted hemoglobin with a special synthetic polymer to prevent it from breaking down.

The result is a product that can be freeze-dried as a powder, in addition it’s immune silent, meaning they can be used with any blood type, and can be stored at room temperature and mixed with water, ready for immediate use anywhere. This synthetic cells has been tested in mice, and are now being tested in larger animals. Doctor says he hopes the product will enter human trials within a decade.