Blood: This is what makes people’s elixir of life so special

Man dies without blood. The elixir of life supplies the body with oxygen, vitamins and hormones. Will it ever be possible to make it without someone else having to bleed for it?

People cannot live without blood: four and a half to six liters flow through the vessels of an adult. If a third is missing, the cycle breaks down. Blood carries oxygen from the lungs and nutrients from the digestive tract to all cells. Hormones circulate in the blood, as do killer cells that eat viruses and other pathogens along the way. The body transports superfluous substances out through the blood to the kidneys, while toxins are flushed to the liver, which takes care of their breakdown.

And that’s not all: blood keeps the acid-base balance stable and even the temperature constant. When it is hot, the blood vessels widen so that the body can give off heat. When it’s cold, they contract so as not to lose any heat. If a blood vessel is injured, highly specialized blood cells close the leak. So blood is truly an elixir of life.


This is made possible by its finely dosed mixture of cells and fluid. What can doctors read from it? What are the consequences if blood cells or proteins are disturbed? And will you ever be able to receive a blood donation without someone else having to bleed for it?

What’s in the blood?

Blood looks liquid, but only plasma is liquid. The mixture makes up more than half, namely 55 percent. It contains nutrients and minerals, vitamins, electrolytes, hormones, waste products and proteins. The latter are responsible for blood clotting and important for the body’s immune defense.

There are billions of solid particles floating around in every liter of blood, the blood cells. 44 percent of these are red blood cells. These erythrocytes bind oxygen, more precisely the dye hemoglobin, which gives them their red color. The final percent is made up of white blood cells and platelets – called leukocytes and platelets. Leukocytes are used for defense, platelets are responsible for clotting.


Because the blood has to be constantly renewed, there is a blood factory in the bone marrow: Two million new blood cells are created there every second from stem cells, says doctor Edgar Jost, specialist in internal medicine at the RWTH Aachen University Hospital. The replenishment is urgently needed: “Most white blood cells and platelets have a lifespan of three to four days. Red blood cells last for three to four months.”

What if the blood is disturbed?

To prevent people from bleeding to death if a vessel ruptures or if you injure yourself, blood has the ability to clot. Again, while it flows through the body, it must not become too thick. Otherwise blood vessels threaten to close up. The coagulation system is correspondingly complex.

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Various enzymes ensure that everything runs correctly. The principle is based on an enzyme chain in which ineffective precursors of the coagulation factors become effective enzymes. One change causes the next. This also means that if one enzyme does not do exactly what it should, the system is disturbed.

A particularly important enzyme is thrombin. This coagulation factor ensures that fibrinogen becomes thread-like fibrin. If there is enough, liquid blood becomes gelatinous. This is very good when it comes to sealing a damaged vessel, but bad when it is blocked. Possible serious consequences are a heart attack or stroke.

The opposite is the case in people with hemophilia, also known as hemophilia. For example, you can bleed to death from a tiny injury because the body does not properly produce a single coagulation factor (see p. XX). There are essentially two types of the disease: In people with haemophilia A, the gene for coagulation factor VIII is changed. About one in 5000 newborns is affected. Hemophilia B – with factor IX changed – is up to six times less common. The severity of the disease depends on the type and extent of the mutation.

What is blood cancer (leukemia)?

Stem cells divide and mature. Again and again until a blood cell is formed. However, it can happen that an immature cell mutates. The cells do not continue to grow from now on, but they multiply diligently. Ultimately, billions of these degenerate cells are buzzing around in the body, accumulating and displacing the healthy ones. The result: fewer red and white blood cells and platelets are produced.

Without this, however, the blood is no longer functional. The risk of contracting pathogens is increased; anemia or bleeding may occur. If the degenerated cells spread in the body, organs such as the kidney, liver or even the brain weaken.

According to the German Cancer Society, more than 13,000 people develop leukemia every year in Germany. Depending on the cell type involved, doctors differentiate between myeloid and lymphatic leukemia. Myeloid leukemia originates from the preliminary stages of erythrocytes, thrombocytes, granulocytes and monocytes, the others from preliminary stages of lymphocytes.

In addition, doctors differentiate between acute and chronic diseases. “Chronic lymphocytic leukemia in people aged 50 and over is the most common but less dangerous form,” explains Edgar Jost, a doctor from Aachen. The second most common form, acute myeloid leukemia, “must be treated immediately so that it does not become fatal”.

What are blood samples good for?

To this day, modern medicine would be inconceivable without blood samples. Because doctors can use the sample to see how the body is doing. Diseases can be seen in the blood long before symptoms appear. Or the other way around: Doctors can prove a heart attack that has gone unnoticed, even if the EKG shows normal values ​​again. Namely via the enzyme creatine kinase, which accumulates in the blood due to a heart attack.

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Just a few milliliters tell doctors a lot: “The blood shows whether the liver and kidneys are healthy or someone has diabetes,” says Jost. “We also see how well a person is supplied with nutrients and whether cholesterol and triglycerides increase their risk of cardiovascular disease.”

To check how the patient is doing, doctors do a blood count. You determine the size and shape of the red and white blood cells and see how many red blood cells are on the move. If something is suspicious, a doctor needs a differential blood count, in which a device counts the different types of white blood cells. The ratio reveals more about the possible disease: Does a virus cause problems? A medicine? Is it even a tumor?

Jost is convinced that the blood will soon reveal a lot more: “The PSA test for the early detection of prostate cancer has been around for a long time. In two to ten years, I am sure, we will be able to test blood on the diseased genetic material of various tumor cells investigate.” Such tests are still in the development phase, but a lot has happened recently in research into breast and lung cancer. “Tests for viral, bacterial and fungal DNA are also on the rise.”

Can blood be produced artificially?

People get sick or have accidents. Blood from donors can help them, even save lives. But there are too few regular donors to ensure that everyone is taken care of. The hope: artificial blood.

However, so far all attempts to artificially produce human blood have failed. “Scientists have been trying to replicate red blood cells in the laboratory for several decades,” reports doctor Edgar Jost. Above all, the shell of human erythrocytes complicates the work – it can hardly be imitated. “Up until now, the artificial oxygen carriers were either too big and clogged the kidney’s filter systems, or they were too small and simply excreted in the urine.”

It would be an advantage in future not to be dependent on blood supplies from humans for transfusions: there would no longer be a risk of transmitting diseases with the substitute blood; And you don’t have to worry about suitable blood groups, correct storage or the limited availability and shelf life. The artificial products would also last longer than real blood. “But technically it’s not that easy,” says Jost.

There are many ideas. In Germany, researchers are working on stem cells that can develop into functioning red blood cells. A team of Chinese and US researchers has recreated artificial blood cells with the help of silica gel covers and tried them out in chicken eggs and mice. The particles from the laboratory should later be at least good enough to bring drugs to their destination in the body, according to the specialist magazine “ACS Nano”.

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In addition, doctors have been using the carbon compound perfluorocarbon for “liquid ventilation” since the 1960s. Patients do not receive air, but a liquid enriched with oxygen. The method never became the standard, but research is still being carried out at some universities.

What about hemoglobin research?

Some researchers want to create replacement blood with the help of the blood pigment hemoglobin. In the United States, a team developed a product made from bovine blood that is already approved for human use in South Africa. The oxygen-binding solution also makes donor livers usable again, which initially seem unsuitable for a transplant.

The Frenchman Franck Zal thinks he is close to perfect fake blood. The biologist from France sees the hemoglobin of the lugworm as the ideal blood substitute for humans. The molecule binds 40 times more oxygen than human hemoglobin and is compatible with all blood groups, he says. Zal has already tested his product on mice and rabbits and used it to preserve donor organs – allegedly without complications. The further examination is pending.

As exciting as these approaches sound, they have a catch. Because at the end of all ideas there are only oxygen carriers that only take on one of the many functions of the blood. As long as vital components such as platelets or white blood cells are missing, there can be no question of a real replacement. “Making artificial blood is a wonderful dream,” says the Aachen-based hematologist Jost. “But for a few decades we will still be dependent on blood donors.”

What can I do to improve my blood?

The options are limited. Jost advises a healthy diet with plenty of fresh vegetables. For example, lettuce, asparagus, peas and tomatoes contain folic acid, which the body needs to produce red and white blood cells. Vitamin B too12 is important for the construction of the erythrocytes. Because it is mainly found in liver, fish, eggs and cheese, vegans risk a deficiency, warns Jost: “Take vitamin B.12 if you don’t add one, they often develop anemia. “

Regular blood donation is also recommended to keep the blood healthy. For example, it stimulates the renewal process in the bone marrow. The donation can also lower the blood pressure of hypertensive patients, thereby reducing the risk of cardiovascular disease. Before making a donation, the blood is also checked for possible weaknesses, such as iron deficiency. Afterwards, in many places there is a test for infectious diseases such as syphilis, HIV or hepatitis. And what is known can be treated.