Blood is essential to life.
This constantly circulating fluid provides the body with nutrition, oxygen, and waste removal. It is made up of four components, namely red and white blood cells, platelets, and plasma.
Plasma:
Plasma is the light, amber colored liquid component, which makes up about 55% of the volume of blood, with the remaining 45 % made up of red blood cells, white blood cells, and platelets, all suspended in the plasma. Plasma makes the blood a fluid and consists of about 90-92% water. It contains solutes which are critical for sustaining health and life, including electrolytes such as sodium, potassium, chloride, magnesium, calcium, and bicarbonate. Within the plasma are about 7% vital proteins such as albumin, gamma globulin and anti-hemophilic factor, and 1% mineral salts, sugars, fats, hormones, and vitamins.
Plasma serves additional vital functions in the body:
- Helping to maintain blood pressure and volume.
- Carrying critical proteins for blood clotting and immunity.
- Helping to maintain the pH balance in the body, which supports cell functions.
Our blood is the river of nourishment for the cells in our bodies and the health of our cells depends on healthy blood.
Plasma exchange for therapeutic reasons:
Plasma is derived when all the blood cells and platelets are separated from whole blood. Healthcare providers use a process called plasmapheresis to obtain plasma from blood by taking blood and using a cell separator machine to separate plasma from the cellular component of blood. This process is often used to obtain donor plasma from healthy people, for use when treating certain medical conditions.
Plasma exchange refers to a process when healthcare providers use plasmapheresis to separate plasma from the rest of the blood. The old plasma is discarded, and replacement fluid (healthy plasma from a donor or albumin fluid) is added to the blood, which is then returned to the patient, in a continuous process.
Modern technology and the availability of the latest upgraded apheresis machines allow the most selective possible removal of pathological components in the blood.
How plasma exchange is done:
A plasma exchange procedure involves a few steps:
- A needle or intravenous line is inserted into one arm of the patient.
- Small amounts of blood are gradually removed and fed into a plasma apheresis machine.
- The plasma apheresis machine (also known as a cell separator machine) separates the plasma from the cellular blood components – red blood cells, white blood cells, and platelets.
- The filtered plasma is removed and discarded.
- The preserved blood cells are then reconstituted with replacement fluid such as (healthy) plasma or albumin fluid with cellular function promoting factors.
- The reconstituted blood is then reinfused back into the body through an intravenous line in the other arm.
A plasma exchange may take several hours. One such procedure typically would remove about 65-70% of disease-causing proteins (antibodies) in the plasma. Several procedures may be needed to result in clinical improvement.
Conditions treated with plasma exchange:
According to the Cleveland Clinic, therapeutic plasma exchange is used to treat a number of blood disorders, neurologic disorders, and blood cancers – as an initial treatment or by combining it with other treatments. It may also be used to support recovery from organ transplants.
Blood disorders: Healthcare providers treat a few blood disorders with plasma exchange:
- Cryoglobulinemia is a condition where proteins called cryoglobulins clamp together in the blood, which results in clogging of the arteries, as well as causing inflammation and organ damage. Plasma exchange removes cryoglobulins which may block the arteries.
- Thrombotic thrombocytopenic purpura is a condition in which blood clots form in small blood vessels, using up the platelets and resulting in a low platelet count. Plasma exchange remove unhealthy antibodies from the blood.
Neurological disorders: Healthcare providers may use plasma exchange to remove harmful antibodies from patient’s plasma for several disorders:
- Multiple sclerosis (MS) – when proteins in the plasma attack the body with sudden, severe symptoms in patients with MS, plasma exchange is used to help patients cope with these severe symptoms.
- Guillain-Barre syndrome happens when the immune system attacks the nerves and plasma exchange is used to filter out the attacking antibodies in the plasma.
- Myasthenia gravis happens when antibodies in the immune system attack healthy tissue instead of intruders and plasma exchange is used to filter out the abnormal antibodies.
Cancer: A few types of cancer are treated with plasma exchange:
- Lymphoplasmacytic lymphoma is a type of blood cancer that occurs when unusually large amounts of the antibody immunoglobin M are produced in the lymphoid cells in the bone marrow or lymph nodes and plasma exchange is used to filter out the antibodies.
- Multiple myeloma is a type of blood cancer that occurs when the bone marrow produces abnormal plasma cells, which become cancerous and multiply. These abnormal plasma cells are removed with plasma exchange.
In addition to these conditions, the academic medical center at the University of Texas’ (UT Southwestern Medical Center) includes several other conditions where therapeutic plasma exchange is used at their facilities:
- Antibody-mediated rapidly progressive glomerulonephritis – a syndrome characterized by progressive loss of kidney function.
- Chronic inflammatory demyelinating polyradiculoneuropathy – an autoimmune disease destroying myelin, the protective fatty covering of nerves.
- Hyper-viscosity syndrome – a condition that prevents blood flowing freely through veins.
- Recurrent focal segmental glomerulosclerosis – this condition can occur after a kidney transplant and may lead to end-stage renal disease.
- Transplant rejection of solid organs – this may occur after transplants of organs such as the heart, lung, or kidney.
- Neuromyelitis optica spectrum disorder – this neurological disease is characterized by inflammation of the optic nerve and the spinal cord.
- Autoimmune encephalitis – a disorder in which the immune system attacks the brain. Clinical manifestations include behavioral and psychiatric symptoms, autonomic disturbances, movement disorders, and seizures.
- Stiff-person syndrome – this neurological disorder causes muscle stiffness.
Potential of plasma exchange to treat Alzheimer’s disease:
Alzheimer’s disease results from loss of the brain’s neurons and synapses. The brain of an Alzheimer’s patient displays tangles and plaques that affects the transfer of impulses between neurons. The tangles and plaques are the main contributors to Alzheimer’s disease, and these were identified by researchers as tau protein tangles and amyloid-beta plaque build-up.
Tau is a normal protein that transports nutrients into brain cells and move waste products out of brain cells. Aging, or errant genes, can cause tau to become abnormal, resulting in pieces of the tau protein to tangle and clump together. In this event the nutrients and toxic waste products can no longer move freely within brain cells and these cells may eventually die. The neurofibrillary tangles are bundles of filaments composed primarily of tau protein, which often first form in the regions in the brain that is used for memory but can soon spread across the rest of the brain.
The fatty membrane that surrounds brain cells contain a protein molecule called amyloid-beta, which can cause plaque build-up outside the cells of the brain when it clumps together.
As amyloid-beta tends to bind to circulating albumin (the most abundant protein in plasma), researchers investigated the possibility that routine plasma exchange might inhibit the forming and disassembly of amyloid-beta in the blood as well as in the cerebrospinal fluid that soaks the brain. In theory the removal of amyloid-beta from plasma may result in the amyloid-beta in cerebrospinal fluid segregating into the plasma.
A major international study in Spain and the USA, called Alzheimer’s Management by Albumin Replacement (AMBAR), found that plasma exchange could slow down cognitive decline, with improved language fluency and processing speed in patients with mild Alzheimer’s and improved short-term verbal memory in patients with moderate Alzheimer’s, with an improvement in quality of life as measured by caregivers.
Further studies are needed to investigate the mechanisms by which albumin replacement appears to improve moderate Alzheimer’s symptoms.
Plasma exchange facilities in South Africa:
The South African National Blood Service (SANBS) provides therapeutic plasma exchange services for hematology, neurology, oncology, and nephrology conditions to patients in private and public hospitals. The following conditions are listed for treatment:
- Guillain-Barre syndrome
- Myasthenia gravis
- Chronic inflammatory demyelinating polyradiculoneuropathy
- N-Methyl-D-Aspertate Receptor Encephalitis – a type of brain inflammation caused by antibodies.
- Neuromyelitis optica spectrum disorder.
- Multiple sclerosis (MS).
- Acute transverse myelitis – a rare, acquired neurological condition caused by inflammation of the spinal cord.
Conclusion:
Plasma exchange forms part of the overall treatment for conditions such as blood disorders, blood cancers and neurological diseases. It may potentially improve Alzheimer’s disease symptoms, pending further research. While plasma exchange does not cure these conditions, it does ease the symptoms that may impact quality of life.
References:
Therapeutic plasma exchange – an emerging treatment modality in patients with neurologic and non-neurologic diseases. Published 1 August 2017. Journal of Clinical and Diagnostic Research. PubMed Central. (www.ncbi.nlm.nih.gov).
Plasmapheresis and plasma exchange. Reviewed 20 September 2022. Cleveland Clinic. (www.clevelandclinic.org)
Therapeutic plasma exchange for neurology patients. Published online. South African National Blood Services. (www.sanbs.org.za)
Therapeutic plasma exchange. Published online. University of Texas Southwestern Medical Center. Dallas USA. (www.utswmed.org)
The importance of plasma in blood. Published online. American Red Cross. (www.redcrossblood.org)
Plasma exchange for Alzheimer’s disease management by Albumin replacement (AMBAR) trial: study design and progress. Published 26 February 2019. PubMed Central. (www.ncbi.nlm.nih.gov).
Plasma. Published 1 June 2020. Encyclopedia Britannica. (www.britannica.com)
Blood plasma exchange slows Alzheimer’s in landmark clinical trial. Published 10 January 2022. The official information source for Nicotinamide Mononucleotide, a project of ALSET Foundation. (www.nmn.com)
Plasma exchange in Alzheimer’s disease. Published 5 September 2022. ScienceDirect. (www.sciencedirect.com)
HEALTH INSIGHT
