Plasma contains a large variety of proteins including albumin, immunoglobulin, and clotting proteins such as fibrinogen in it. These proteins present in it have many important therapeutic uses and clinical uses and can work wonders when used in development of various medicines. These substances are also widely used in medical researches to develop therapies and vaccines for chronic diseases like cancer, tumors and AIDS etc.
In order to get the benefit of these live saving substances plasma is extracted from the human blood through a process called blood fractionation. Human Plasma is the yellowish liquid present in the human blood that constitutes 55% of its volume and is responsible for all the major circulation of it throughout the human body. When this extraction is carried out we get a clear solution of plasma in the upper phase, the Buffy coat, which is a thin layer of leukocytes mixed with platelets in the middle and Erythrocytes (Red Blood Cells) at the bottom of the centrifuge tube. After getting these components separately in the tube, plasma can be separated easily and stored for further use.
Now once the Human Plasma is obtained, its various components can be separated for further usage. However it is also very beneficial and can be used in various forms to create medications wholly. The process of separating the various components of Human Blood Plasma is called as Blood plasma fractionation.
The Human Blood Plasma contains thousands of proteins, however, identifying them presents challenge due to the wide range of concentrations present in it. Let us see different components and their concentration in it.
- Albumin constitutes about 60% of the total protein in plasma and is present at concentrations between 35 and 55 mg/mL. It is the main contributor to osmotic pressure of the blood and it functions as a carrier molecule for molecules with low water solubility such as lipid soluble hormones, enzymes, fatty acids, metal ions, and pharmaceutical compounds. Due to the structural integrity of albumin it remains stable under conditions where most other proteins denature.
- Fibrinogen is present at concentrations 1.5-4.0 g/L in Human Blood Plasma or about 7 µM. It is the principal protein responsible for clotting in the human body.
- Immunoglobulins are the substances that fight against infections in human body. Our bodies create antibodies (Immunoglobulin’s) against disease causing agents when infections occur.
Apart from these there are many other proteins and substances present in the human plasma in minute quantities that also can be separated through the process of Blood plasma fractionation.
The first practical large scale method of blood plasma fractionation was developed by Edwin J. Cohn during World War II. This process is also known as cold ethanol fractionation as it involves gradually increasing the concentration of ethanol in the solution at 5oC and 3oC. The Cohn Process exploits differences in properties of the various proteins, specifically, the high solubility and low pl of albumin. However, at each stage certain proteins are precipitated out of the solution and removed. The final precipitate is purified albumin.
Several variations to this process also exist, including an adapted method by Nitschmann and Kistler that uses fewer steps, and replaces centrifugation and bulk freezing with filtration and diafiltration. However, the ultimate goal of processing is to get a purified component that can be used for making injection or transfusions. In addition to the clinical uses of a variety of its proteins, it has many analytical uses too. Blood plasma fractionation obtains it in purified state that can be utilized for many purposes and have many beneficial factors in it.