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Blood plasma fractionation
View on WikipediaBlood plasma fractionation are the general processes separating the various components of blood plasma, which in turn is a component of blood obtained through blood fractionation. Plasma-derived immunoglobulins are giving a new narrative to healthcare across a wide range of autoimmune inflammatory diseases.[citation needed]
Blood plasma
[edit]Blood plasma is the liquid component of whole blood, and makes up approximately 55% of the total blood volume. It is composed primarily of water with small amounts of minerals, salts, ions, nutrients, and proteins in solution. In whole blood, red blood cells, leukocytes, and platelets are suspended within the plasma.[citation needed]
Plasma proteins
[edit]Plasma contains a large variety of proteins including albumin, immunoglobulins, and clotting proteins such as fibrinogen.[1] Albumin constitutes about 60% of the total protein in plasma and is present at concentrations between 35 and 55 mg/mL.[2] 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.[3] Albumin is structurally stable due to its seventeen disulfide bonds and unique in that it has the highest water solubility and the lowest isoelectric point (pI) of the plasma proteins. Due to the structural integrity of albumin it remains stable under conditions where most other proteins denature.[citation needed]
Plasma proteins for clinical use
[edit]Many of the proteins in plasma have important therapeutic uses.[1] Albumin is commonly used to replenish and maintain blood volume after traumatic injury, during surgery, and during plasma exchange.[3] Since albumin is the most abundant protein in the plasma its use may be the most well known, but many other proteins, although present in low concentrations, can have important clinical uses.[1] See table below.[1]
| Plasma Component | Reasons for Use |
|---|---|
| factor VIII | hemophilia A |
| factor IX | hemophilia B |
| Factor X | congenital deficiency |
| factor XIII | congenital deficiency |
| PCC complex | anticoagulant overdose
factor II and factor X if Factor X not available deficiencies liver disease |
| immunoglobulin | passive prophylaxis immune deficiency disorders |
| antithrombin III | congenital deficiency |
| fibrinogen | congenital deficiency
massive haemorrhage |
| C1 inhibitor | hereditary angioedema |
| albumin | hypoalbuminemia
Ascites Restoring of blood volume in trauma, burns and surgery patients |
| alpha-I-antitrypsin | hereditary deficiencies |
Plasma processing
[edit]When the ultimate goal of plasma processing is a purified plasma component for injection or transfusion, the plasma component must be highly pure. The first practical large-scale method of blood plasma fractionation was developed by Edwin J. Cohn during World War II. It is known as the Cohn process (or Cohn method). This process is also known as cold ethanol fractionation as it involves gradually increasing the concentration of ethanol in the solution at 5 °C and 3 °C.[3] The Cohn Process exploits differences in properties of the various plasma proteins, specifically, the high solubility and low pI of albumin. As the ethanol concentration is increased in stages from 0% to 40% the [pH] is lowered from neutral (pH ~ 7) to about 4.8, which is near the pI of albumin.[3] At each stage certain proteins are precipitated out of the solution and removed. The final precipitate is purified albumin. Several variations to this process exist, including an adapted method by Nitschmann and Kistler that uses fewer steps and replaces centrifugation and bulk freezing with filtration and diafiltration.[1][3]
Some newer methods of albumin purification add additional purification steps to the Cohn Process and its variations, while others incorporate chromatography, with some methods being purely chromatographic.[3] Chromatographic albumin processing as an alternative to the Cohn Process emerged in the early 1980s, however, it was not widely adopted until later due to the inadequate availability of large scale chromatography equipment.[3] Methods incorporating chromatography generally begin with cryodepleted plasma undergoing buffer exchange via either diafiltration or buffer exchange chromatography, to prepare the plasma for following ion exchange chromatography steps.[3] After ion exchange there are generally further chromatographic purification steps and buffer exchange.[3]
For further information see chromatography in blood processing.
Plasma for analytical uses
[edit]In addition to the clinical uses of a variety of plasma proteins, plasma has many analytical uses. Plasma contains many biomarkers that can play a role in clinical diagnosis of diseases, and separation of plasma is a necessary step in the expansion of the human plasma proteome.[citation needed]
Plasma in clinical diagnosis
[edit]Plasma contains an abundance of proteins many of which can be used as biomarkers, indicating the presence of certain diseases in an individual. Currently, 2D Electrophoresis is the primary method for discovery and detection of biomarkers in plasma. This involves the separation of plasma proteins on a gel by exploiting differences in their size and pI. Potential disease biomarkers may be present in plasma at very low concentrations, so, plasma samples must undergo preparation procedures for accurate results to be obtained using 2D Electrophoresis. These preparation procedures aim to remove contaminants that may interfere with detection of biomarkers, solubilize the proteins so they are able to undergo 2D Electrophoresis analysis, and prepare plasma with minimal loss of low concentration proteins, but optimal removal of high abundance proteins.[citation needed]
The future of laboratory diagnostics are headed toward lab-on-a-chip technology, which will bring the laboratory to the point-of-care. This involves integration of all of the steps in the analytical process, from the initial removal of plasma from whole blood to the final analytical result, on a small microfluidic device. This is advantageous because it reduces turn around time, allows for the control of variables by automation, and removes the labor-intensive and sample wasting steps in current diagnostic processes.[citation needed]
Expansion of the human plasma proteome
[edit]The human plasma proteome may contain thousands of proteins, however, identifying them presents challenges due to the wide range of concentrations present. Some low abundance proteins may be present in picogram (pg/mL) quantities, while high abundance proteins can be present in milligram (mg/mL) quantities. Many efforts to expand the human plasma proteome overcome this difficulty by coupling some type of high performance liquid chromatography (HPLC) or reverse phase liquid chromatography (RPLC) with high efficiency cation exchange chromatography and subsequent tandem mass spectrometry for protein identification.[2][4]
See also
[edit]References
[edit]- ^ a b c d e Brodniewicz-Proba, T. 1991. "Human Plasma Fractionation and the Impact of New Technologies on the Use and Quality of Plasma-derived Products". Blood Reviews. Vol. 5. pp. 245–57.
- ^ a b Shen, Y., Jacobs, J. M., et al. 2004. "Ultra-High-Efficiency Strong Cation Exchange LC/RPLC/MS/MS for High Dynamic Range Characterization of the Human Plasma Proteome". Anal Chem. Vol. 76. pp. 1134–44.
- ^ a b c d e f g h i Matejtschuk, P., Dash, C.H., and Gascoigne, E.W. 2000. "Production of human albumin solution: a continually developing colloid". British Journal of Anaesthesia. Vol 85. pp. 887–95.
- ^ Wu, S., Choudhary, G., et al. 2003. "Evaluation of Shotgun Sequencing for Proteomic Analysis of Human Plasma Using HPLC coupled with Either Ion Trap or Fourier Transform Mass Spectrometry". Journal of Proteome Research. Vol. 2. pp. 383–93.
Blood plasma fractionation
View on GrokipediaFundamentals of Blood Plasma
Composition and Properties
Blood plasma is the straw-colored liquid component of blood, constituting approximately 55% of total blood volume and serving as the medium in which blood cells are suspended.[7] It consists primarily of water, accounting for 90% to 92% of its composition, with the remaining 8% to 9% comprising dissolved solids such as proteins, electrolytes, nutrients, hormones, and waste products.[8][9] The protein content of plasma totals 60 to 80 g/L, with albumin representing the predominant fraction at 35 to 50 g/L; these proteins collectively contribute to maintaining the plasma's colloidal osmotic pressure, approximately 25 mmHg, which helps regulate fluid balance between blood vessels and tissues.[10][11][8] Non-protein components include electrolytes such as sodium (135–145 mmol/L), potassium (3.5–5 mmol/L), and chloride (98–107 mmol/L), which are essential for osmotic balance and pH regulation; glucose, typically 3.9–5.5 mmol/L in fasting states; lipids like cholesterol and triglycerides transported in lipoprotein forms; and dissolved gases including oxygen, carbon dioxide, and nitrogen.[12][13] Key physical and chemical properties of plasma include a pH range of 7.35 to 7.45, which is slightly alkaline and tightly buffered by electrolytes and proteins to support enzymatic functions and oxygen transport.[14] Its viscosity, approximately 1.2 to 1.3 mPa·s at 37°C, arises mainly from protein concentrations and influences blood flow resistance.[15] Plasma plays a critical role in nutrient transport (e.g., glucose and amino acids), waste removal (e.g., urea and carbon dioxide), and overall homeostasis, making it the foundational material for fractionation processes that isolate therapeutic components.[8][7]Sources and Collection
Blood plasma for fractionation is primarily obtained from two sources: source plasma collected directly via plasmapheresis from healthy donors and recovered plasma derived from whole blood donations.[16] In plasmapheresis, an automated process draws whole blood from the donor, separates the plasma using centrifugation within the apheresis machine, and returns the cellular components (red blood cells, white blood cells, and platelets) along with saline to the donor, allowing for more frequent collections compared to whole blood donation.[17] Recovered plasma, on the other hand, is separated from whole blood units collected for transfusion purposes, where the plasma is removed post-donation via centrifugation, leaving the red blood cells for other uses.[16] The vast majority of plasma used for manufacturing plasma-derived medicinal products comes from source plasma via plasmapheresis, as it enables higher volumes and repeated donations.[18] Collection adheres to strict standards to ensure donor safety and plasma quality. In the United States, regulated by the Food and Drug Administration (FDA), eligible donors must be at least 18 years old, weigh a minimum of 110 pounds (50 kg), and pass a comprehensive health screening, including medical history review and testing for infectious diseases such as HIV, hepatitis B and C, and syphilis.[19] Volume limits per session are determined by FDA-approved nomograms based on donor factors like sex, height, weight, and hematocrit, with a typical maximum of up to 800 mL for qualifying adults.[20] Frequency is capped at no more than twice per week, with at least 48 hours between donations, to minimize risks like protein depletion or dehydration.[21] Post-collection processing begins immediately to preserve protein integrity. For recovered plasma from whole blood, centrifugation separates the plasma within hours of donation, followed by freezing at -20°C or lower within 24 hours to maintain clotting factors and other labile proteins.[22] Source plasma from plasmapheresis is similarly frozen promptly after collection, often at -25°C to -30°C for optimal preservation, using rapid freezing methods to reach core temperatures below -25°C within 12 hours.[23] Frozen plasma units are stored at -20°C or colder, with FDA guidelines permitting a shelf life of up to 10 years for source plasma intended for fractionation, though lower temperatures like -30°C can extend stability further.[24] Globally, the plasma supply for fractionation relies heavily on a mix of paid and voluntary donations, with significant variations by region. The United States dominates as the largest supplier, providing approximately 70-75% of the world's source plasma through high-volume commercial centers that compensate donors, enabling frequent collections and meeting international demand for plasma-derived therapies.[25][26] In contrast, many countries, including those in the European Union, emphasize voluntary unpaid donations, which constitute over 90% of blood supplies in 79 nations but result in lower plasma volumes for fractionation due to less frequent collections.[27] This reliance on U.S. paid plasma underscores the commercial nature of the global market, where the U.S. exports much of its supply to support manufacturing worldwide.[28]Plasma Proteins
Types and Classification
Blood plasma contains a diverse array of proteins, with recent deep proteomic analyses identifying over 13,000 unique proteins as of 2025, though plasma fractionation processes primarily target approximately 50 clinically relevant proteins that are structurally characterized and functionally significant.[29][30] These proteins are classified by their primary functions, including carrier proteins such as albumin, which binds and transports various molecules; immune proteins like immunoglobulins (IgG, IgA, and IgM), which contribute to humoral immunity; clotting factors including fibrinogen and coagulation factors II, V, VIII, and IX, essential for hemostasis; and regulatory proteins such as components of the complement system and enzymes like proteases, which modulate physiological processes.[8][31][9] Plasma proteins are further categorized by their abundance, reflecting their relative concentrations in the protein-rich fluid component of blood. High-abundance proteins include albumin, comprising 50-60% of total plasma proteins at concentrations of 35-50 g/L, and globulins, accounting for 35-45% or about 20-35 g/L. Medium-abundance proteins, such as fibrinogen, are present at 2-4 g/L, representing roughly 4-7% of the total. Low-abundance proteins, including many trace clotting factors and regulatory components, occur at concentrations below 1 mg/L, often in the range of 0.1-0.5 mg/L for specific factors like VIII.[8][32][31] Structurally, most plasma proteins are glycoproteins, featuring carbohydrate moieties that influence their stability and interactions. Key examples include albumin with a molecular weight of approximately 66 kDa, enabling its high solubility; IgG at around 150 kDa, composed of two heavy chains (50 kDa each) and two light chains (22 kDa each); and fibrinogen at about 340 kDa as a dimeric structure. These proteins exhibit varying solubility properties, such as differential precipitation in response to changes in pH, ionic strength, and ethanol concentration, which underpin their separation during fractionation without compromising integrity.[33][30][8]Biological Functions
Plasma proteins serve essential physiological roles in maintaining homeostasis, including osmotic balance, immune defense, and hemostasis. These proteins, primarily synthesized by the liver, constitute about 7% of plasma's dry weight and include albumin, globulins (such as immunoglobulins and clotting factors), and other regulatory components. Their functions are interconnected, ensuring fluid distribution, pathogen clearance, and clot formation to prevent excessive bleeding or thrombosis.[8] Albumin, the most abundant plasma protein at approximately 35-50 g/L, plays a critical role in maintaining colloid osmotic pressure, which is around 25 mmHg and counteracts hydrostatic pressure to retain fluid within the vascular compartment. This oncotic pressure prevents edema by regulating the movement of water across capillary walls. Additionally, albumin acts as a carrier for various substances, binding and transporting fatty acids, bilirubin, hormones, and drugs throughout the bloodstream, thereby facilitating their distribution and metabolism.[8][34] Immunoglobulins, or antibodies, are key components of adaptive immunity, produced by plasma cells in response to antigens. They mediate antibody-dependent immunity through mechanisms such as opsonization, where they coat pathogens to enhance phagocytosis by immune cells like macrophages, and neutralization, which blocks pathogen attachment to host cells by binding to viral or bacterial surface proteins. These actions protect against infections from bacteria, viruses, fungi, and parasites, with major classes including IgG (opsonization and complement activation) and IgM (early response and agglutination).[35][36][37] Clotting factors, a group of plasma proteins such as fibrinogen, prothrombin, and factors VIII and IX, orchestrate the coagulation cascade to achieve hemostasis. This enzymatic cascade amplifies signals to form a stable clot: thrombin cleaves fibrinogen into insoluble fibrin strands that polymerize into a mesh, trapping platelets and red blood cells to seal vascular injuries. Factor VIII, in complex with von Willebrand factor, accelerates factor IX activation in the intrinsic pathway, crucial for amplifying the response; its deficiency underlies hemophilia A, leading to impaired clot formation and prolonged bleeding.[38][39][40] The complement system, comprising over 30 plasma proteins including C3 and C5, contributes to innate immunity by opsonizing pathogens, promoting inflammation through anaphylatoxins like C5a that recruit immune cells, and lysing microbes via the membrane attack complex. Complement enzymes, activated in classical, alternative, or lectin pathways, also modulate inflammation by cleaving proteins to generate chemotactic signals and enhance antibody efficacy. Other plasma enzymes, such as those in the fibrinolytic system (e.g., plasmin derived from plasminogen), facilitate protein degradation by breaking down fibrin clots post-hemostasis, preventing thrombosis while regulating inflammatory responses.[41][42] Deficiencies in plasma proteins disrupt these interdependent functions, often leading to disease. For instance, hypoalbuminemia reduces oncotic pressure, causing fluid leakage into tissues and resulting in edema or ascites, as seen in liver cirrhosis where impaired synthesis exacerbates portal hypertension. Immunoglobulin deficiencies impair pathogen neutralization, increasing infection susceptibility, while clotting factor shortages like factor VIII deficiency provoke hemorrhagic disorders. Complement deficiencies heighten autoimmune or infectious risks due to unchecked inflammation or poor pathogen clearance.[11][34][8]History of Plasma Fractionation
Early Developments
The foundations of blood plasma fractionation emerged in the 19th century through initial explorations of blood protein separation. In 1856, French chemist Paul-Sébastien Denis demonstrated the separation of blood proteins into albumins and globulins using salt precipitation, providing an early method to exploit differences in protein solubility for isolation from serum.[43] During the 1860s, German physiological chemist Felix Hoppe-Seyler advanced the understanding of plasma components through detailed analyses of blood, including the isolation and characterization of several proteins (termed "proteids" at the time), which highlighted the diversity of soluble fractions in plasma.[44] In the early 20th century, plasma gained recognition as a viable blood substitute, particularly amid the demands of World War I, where whole blood transfusions were logistically challenging. Researchers explored plasma's volume-expanding properties to treat hemorrhagic shock, leading to the 1918 introduction of dried plasma for battlefield transfusions, which offered greater stability and ease of transport compared to liquid whole blood.[45] Edwin J. Cohn's research at Harvard University in the 1920s and 1930s built on these foundations by investigating protein solubility curves, employing ammonium sulfate precipitation to fractionate serum proteins and elucidate their physicochemical behaviors under varying salt concentrations. This work addressed persistent challenges in plasma preparation, including coagulation prevention via anticoagulants like sodium citrate and bacterial contamination through aseptic collection, refrigeration, and early sterilization protocols. By 1939, the establishment of the first organized plasma banks in the United States facilitated systematic storage and distribution, marking a pivotal shift toward scalable clinical application.[46]World War II and Cohn Process
During World War II, the urgent need for stable blood products to treat shock, burns, and hemorrhage in combat zones drove rapid advancements in plasma fractionation, as the United States anticipated involvement in the conflict by spring 1940.[47] The U.S. Navy, through the National Research Council, sponsored research led by Edwin J. Cohn at Harvard Medical School from 1940 to 1945, aiming to develop concentrated human albumin as a plasma substitute that could be easily transported and administered in small volumes without the risks associated with whole blood transfusions, such as incompatibility.[47] This wartime effort transformed Cohn's pre-war studies on protein chemistry into a practical industrial process, enabling the production of fractionated plasma components for military use.[48] The Cohn process, a cold ethanol fractionation method, was developed in 1940 and patented in 1945 (filed as a continuation from 1940), involving stepwise precipitation of plasma proteins through controlled adjustments of ethanol concentration (8-40%), temperature (0-5°C), pH (4.8-7.2), ionic strength, and protein concentration.[49][50] This technique separated plasma into five major fractions: Fraction I (rich in fibrinogen), Fractions II and III (containing gamma globulins and other globulins), Fraction IV (alpha and beta globulins), and Fraction V (primarily albumin).[51] Key collaborators included John T. Edsall, who contributed to the biochemical understanding and large-scale procedures for protein separation.[48] The method exploited differences in protein solubility to isolate pure components efficiently, with albumin from Fraction V serving as the primary product for volume expansion therapy.[48] Production scaled up dramatically through a Harvard pilot plant and contracts with seven commercial firms, processing over 2.3 million blood donations and yielding more than 570,000 packages of albumin by the war's end in 1945, alongside other fractions totaling over 1.2 million units. The first commercial human albumin solution (25% concentration) was authorized for production in January 1942 and became available for clinical use by 1944, following successful trials starting in April 1941.[47] This enabled mass distribution to troops, as demonstrated at Pearl Harbor in December 1941, where albumin helped save burn casualties who might otherwise have perished from shock.[47] The Cohn process significantly reduced transfusion risks by providing stable, heat-sterilizable products that avoided whole blood's logistical challenges and serological incompatibilities, while facilitating the isolation of therapeutic proteins for broader medical applications.[52] Its success marked a pivotal shift toward industrialized biopharmaceutical production, saving countless lives during the war and establishing fractionation as a cornerstone of modern plasma therapy.[48]Fractionation Techniques
Cold Ethanol Fractionation
Cold ethanol fractionation is a cornerstone method for initial separation of blood plasma proteins, relying on the differential solubility of proteins in ethanol solutions at low temperatures. Developed by Edwin J. Cohn and colleagues during World War II, this technique precipitates proteins sequentially by adjusting ethanol concentration, pH, ionic strength, and temperature to target their isoelectric points and minimize denaturation.[53] It remains widely used in the early stages of industrial plasma processing due to its scalability and effectiveness in isolating major protein classes like fibrinogen, immunoglobulins, and albumin.[54] The procedure starts with thawing frozen plasma at 1–5°C to remove cryoprecipitate, yielding cryo-poor plasma that undergoes sequential ethanol additions. Proteins are precipitated by gradual increases in ethanol, with each fraction isolated via centrifugation or filtration; the supernatant proceeds to the next step. The classic Cohn method 6 divides plasma into five main fractions: I (fibrinogen-rich), II+III (immunoglobulins and clotting factors), sub-fractions of III and IV (globulins), and V (albumin). Specific conditions for each precipitation are tightly controlled, as summarized below:[53][55]| Fraction | Ethanol (%) | pH | Temperature (°C) | Key Proteins Precipitated | Protein Yield (% of total) |
|---|---|---|---|---|---|
| I | 8–10 | 6.9–7.2 | –3 to –5 | Fibrinogen, Factor VIII, von Willebrand factor | 5–10 |
| II+III | 20–25 | 6.8–7.0 | –5 | IgG, IgA, IgM, clotting factors II, VII, IX, X | 25 |
| III | 18–20 | 5.2–5.4 | –5 | Additional globulins | Not specified |
| IV-1 | 18–25 | 5.2–6.1 | –5 | α- and β-globulins, IgM, antithrombin III | 5–10 |
| IV-4 | 20–40 | 4.8–6.1 | –5 | α- and β-globulins, ceruloplasmin, transferrin | 5–10 |
| V | 40 | 4.8–5.1 | –5 | Albumin (85–98% purity) | 60–70 |
