Blood Substitutes: A Quest for Artificial Blood

Greetings everyone! Let's talk about blood today. Blood is a unique form of connective tissue made up of plasma, platelets, red blood cells, and white blood cells. It serves a number of purposes in the body. Together with platelets, the supernatant fluid plasma, which is the extracellular substance consisting of water, ions, and other proteins, promotes blood clotting. To stop additional bleeding, proteins in the plasma react with the air and solidify. White blood cells are our bodies first line of defense and the immunological defense is carried out by them.

What is a blood substitute?

About one billion red blood cells can be found in as little as two drops of blood. The movement of carbon dioxide and oxygen throughout the body is carried out by these cells. The body recognizes certain proteins on the membranes of these cells as being its own. A person can only use blood that is compatible with their kind because of this.

So since natural blood is so unique, is there some sort of artificial form of bloods in the market? To answer this question, here comes the blood substitutes. Now, what are they?

A blood substitute, also called as artificial blood or blood surrogate is a substance used to mimic and fulfil some functions of natural blood, usually its oxygen carrying ability. The main aim is to provide an alternative for blood transfusion, which is transferring of blood and blood based products from one person to another.

The history for the quest to develop blood substitutes

From doctors to medical professionals experimented with several things after when William Harvey described how blood circulates in the body. These includes milk, beer, urine, plant resins to sheep blood in place of blood. They had imagined that altering a person's blood may have a variety of positive outcomes, like healing illnesses or even altering a person's immunity. In 1667, the first successful transfusion of human blood had place. Sadly, the practice was discontinued due to the deaths of patients who got subsequent transfusions of blood.

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Salt or saline solutions were still another possible replacement. Through several tests conducted on frogs, scientists discovered that by completely replacing the frogs' blood with a saline solution, they could prolong the frogs' lives. However, it was later discovered that frogs could survive for a little period of time without any blood circulation at all, thus these results were a little misleading. Saline was created as a plasma volume expander after a more in-depth research.

With the discovery of Ringer's solution in 1883 which is basically a mixture of sodium, potassium and calcium salts, opened a new ray of hope in the manufacturing of artificial blood. Using a part of a frog's heart, researchers discovered that by applying the solution, the heart could be kept beating. This subsequently led to the discovery that Ringer's solution may be used to restore the blood pressure fall brought on by a loss of blood volume. When lactate was added, this product changed into a human product. Ringer's solution is still used today as a blood-volume expander, but it is not a genuine blood substitute because it does not take the place of red blood cells' function.

What do they have to possess?

Now, let's talk about what characteristics should a blood substitute possess to become an ideal one. First and foremost, it must be compatible with and safe for use in the human body. Its ability to carry oxygen throughout the body and release it when required is its second requirement. Thirdly, it needs to be shelf stable. Artificial blood, in contrast to blood that we donate, can be kept for a year or more. Natural blood, on the other hand, has a one-month shelf life before it degrades. Two very distinct compounds are now being developed as alternatives to blood. The main distinction between them is how they transport oxygen. One is a product based on PFC (perfluorocarbons) and the other is based on hemoglobin.

Perfluorocarbons (PFC)

The capacity of a class of synthetic molecules known as perfluorocarbons to dissolve a large amount of gases, such as carbon dioxide and oxygen has drawn significant interest. PFCs act as oxygen carriers on their own, in contrast to regular blood that depends on hemoglobin for oxygen delivery. Because of this unique quality, they are a good option to replace blood, particularly in situations where conventional transfusions are not possible or are not readily available.

The stability and long shelf life of PFCs are among their main benefits. PFC-based replacements do not require refrigeration or blood type and they can be kept for longer lengths of time than natural blood supplies that can not be stored for a longer period of time. Because of this quality, they are especially useful in emergency scenarios where there may not be easy access to natural blood.

Hemoglobin-Based Blood Substitutes

Blood replacements based on hemoglobin attempts to separate and purify hemoglobin from human or animal sources or even using recombinant DNA (rDNA) technologies and formulates a solution suitable for blood transfusion. The fact that hemoglobin-based replacements resemble natural blood more closely is one of their main benefits. These replacements imitate the physiological role of red blood cells by using hemoglobin as the oxygen transporter, which enables effective oxygen delivery to tissues. Because of this feature, patients in need of blood transfusions may find them appealing even when there may be a shortage of donated blood or compatibility problems.

Hemoglobin-based alternatives also provide the possibility of targeted oxygen delivery which enables medical professionals to treat individuals according to the needs of each patient. In emergency situations when maximizing oxygen delivery is crucial this precision may prove to be quite helpful.

Have we cracked the code?

Despite these promising advantages, PFCs and hemoglobin-based substitutes also comes bearing its challenges. While PFCs can effectively transport oxygen in a laboratory setting, what we call an in-vitro, their efficiency diminishes in the complex environment of the human body. Likewise, PFCs comes with the potential for oxidative damage caused by free hemoglobin released into the bloodstream.

The Final Words

Both hemoglobin-based blood replacements and perfluorocarbons are exciting options for resolving the issues related to conventional blood transfusions. Even if each strategy has pros and cons of its own, further study and technical developments could eventually allow them to reach their full potential.

Until we meet again!