Artificial Blood - History, Types, Applications, and Limitations

Introduction:

Blood is a type of connective tissue that contains red blood cells, white blood cells, platelets, and plasma. All these components in the blood have unique functions. For example, plasma is the extracellular fluid that contains water, plasma proteins, and salts. It also has platelets, which contribute to blood coagulation (clotting). The white blood cells (WBCs) are responsible for providing the immune defense. They fight the infectious agents in the body. The red blood cells (RBCs) provide the characteristic red color to the blood. They transport oxygen and carbon dioxide throughout the body. Oxyglobin is mainly responsible for transporting oxygen. These RBCs are also responsible for the typing phenomena. They consist of certain proteins on their outer membrane that are mainly responsible for identifying the blood type. It is because of this typing phenomenon that a person can receive blood only of their type. The other type that is not compatible with the person’s blood will be rejected.

Since ages, there has been an urgent need for blood replacements, as many patients have bled to death due to serious trauma or accidents. Scientists had been looking for blood substitutes until they developed artificial blood. Artificial blood is, therefore, designed to replace the sole functions of RBCs (red blood cells). In other words, artificial blood can be referred to as oxygen carriers.

What Is Artificial Blood?

Artificial blood is a blood surrogate or a red blood cell substitute that is developed to mimic and carry out some of the important physiological functions of biological blood (precisely red blood cells). They are also known as blood mimics. They are mainly responsible for transporting oxygen and carbon dioxide throughout the body, hence referred to as oxygen carriers. However, it is not designed to replace all the key functions of the blood, such as blood coagulation and immune defense mechanisms. Its sole purpose is to serve as a temporary support for oxygen delivery and provide life support in patients where blood transfusions are not feasible.

What Is the History of Blood Substitutes?

In the past, many scientists have tried using various fluids as substitutes for blood, such as beer, wine, urine, milk, opium, and even non-human animal blood. But no success was granted. Even saline solutions were tried to replace the biological blood, but the experiments failed. The saline solution was then used as a plasma volume expander (plasma expander).

The breakthrough in the research for blood substitutes came when Professor Landsteiner in the 1900s discovered blood groups and immunochemistry.

Later, plasma donated by humans was being stored and used for blood replacement in the needy patients. In 1966, perfluorochemicals (PFCs) were identified as a new blood substitute. However, the need to develop synthetic oxygen carriers and hemoglobin solutions gained momentum when the shortcomings of the Blood Bank organization came to light during the Vietnam conflict. Efforts to replace blood with blood substitutes are still in progress, and the search for an appropriate synthetic blood substitute is still being made.

Still waiting for human trials in the field of synthetic blood research to find the best red blood cell substitute.

What Are the Ideal Characteristics of Artificial Blood?

• It should be designed in a way that is safe for human use.

• It should be biocompatible within the human body.

• It should be free from any blood typing or blood grouping.

• It should be germ-free and disease-free.

• It should have a good shelf life (for up to a year or so).

• It should be able to transfer oxygen throughout the body.

What Are the Types of Artificial Blood Products?

There are two main types of artificial blood products that are currently being developed and being researched.

Hemoglobin-based Oxygen Carriers (HBOCs) - They are hemoglobin-based products derived from hemoglobin. Hemoglobin (oxyglobin) is the protein present in the red blood cells that is mainly responsible for transporting oxygen to various organs and tissues. So, these HBOCs can be derived from -

1. Human hemoglobin.

2. Animal hemoglobin (bovine or cow blood).

3. Genetically engineered recombinant hemoglobin.

Benefits -

1. It is not contained in a membrane, unlike the natural human blood. Hence, there is no problem with blood type matching.

2. It can be available readily.

3. It has a good shelf life.

4. It can be processed and sterilized to eliminate the blood-borne infections.

5. They mimic the natural function of the biological blood by transporting oxygen throughout the body.

Limitations -

1. Issues with stability as raw hemoglobin will disintegrate into smaller molecules that might cause toxicity in the body.

2. Potential risk of side effects such as oxidative damage and vasoconstriction.

Hemoglobin-based oxygen carriers can be developed using different mechanisms like synthetic production, chemical synthesis, or recombinant biotechnology. Usually an E.coli bacterial strain is used to harvest the synthetic hemoglobin molecule which is then stored in a seed tank and then fermented.

Perfluorocarbon Emulsions - PFCs are biologically inert substances or compounds that can dissolve large volumes of oxygen and carbon dioxide. They can be prepared as emulsified surfactant solutions to be injected intravenously.

Benefits -

1. High oxygen carrying capacity.

2. Long shelf life.

3. Can be manufactured on a large scale.

4. No blood type matching is required.

Challenges -

1. Oxygen delivery is limited as compared to hemoglobin-based oxygen carriers.

2. It can accumulate in the body.

3. Have a slow clearance.

What Are the Applications of Artificial Blood?

Artificial blood can be used to address several clinical problems, including -

• Trauma Cases - To provide immediate care during emergency situations in cases of extreme blood loss.

• Surgery - To manage blood loss and reduce the dependency on donor blood.

• Disaster Cases - To handle situations where the resources are insufficient (limited).

• Chronic Anemia and Other Conditions - Conditions where traditional blood transfusions are not suitable.

• Hemopure - It is currently derived from cow (bovine) hemoglobin and is used in veterinary medicine.

• Oxygent - It is a PFC which is developed for use in surgical procedures but not yet approved for human use.

Conclusion:

More research is needed to improve the potency, safety, and production of artificial blood. Artificial blood (blood mimics) promises a significant role in improving medical care and in conditions where donor blood is hard to get. Scientists should aim to overcome the current challenges and bring these blood substitutes for clinical consumption.