Apheresis-Evolving practices in treatment of patients
Transfusion medicine has undergone diverse and fascinating advancements since its initiation in the early 20th century. One of these is the discovery of apheresis technology. In this blood is drawn from a healthy donor and is separated into components (red blood cells, white blood cells, platelets, and plasma). Required components are transfused to the patients and the remainder is returned to the donor.
Apheresis has been widely used as the primary therapy or as an adjunct to other treatments in critically ill patients suffering from diseases like myasthenia gravis, sickle cell disease, thrombotic thrombocytopenic purpura, hemolytic uremic syndrome, autoimmune disease, and sepsis.
India has 2760 registered blood banks as per Central Drug Standard Control Organization (CDSCO). However not all have facilities for apheresis. Availability of apheresis is mainly restricted to major cities. Key factors in this regard are high equipment cost and availability of skilled manpower.
Apheresis technology is mainly restricted to collection of platelets (plateletpheresis) commonly known as single donor platelets (SDPs). With emergence of dedicated hematological and oncological centers, demand for other subsets like peripheral stem cell collection, therapeutic plasma exchange, cascade filtration, immunoadsorption, leucapheresis, erythrocytapheresis, is steadily increasing.
The elementary techniques in apheresis are well represented by three physical separation methods of blood components: Differential centrifugation; membrane filtration; and adsorption of proteins or cells, from whole blood or from plasma already separated.
Centrifugation technique allows separation of the component fraction based on specific gravity, with RBCs having the greatest relative density followed by granulocytes, monocytes, lymphocytes, platelets, and lastly plasma. Membrane filtration devices separate component fractions based on their size i.e. platelets (2-3µm), RBCs (6-8µm), lymphocytes (10-14µm), and granulocytes (12-15µm). Adsorption technique by use of adsorption columns is used in conjunction with the above two methods.
In comparison to the membrane filtration method, the centrifugation method is more efficient in terms of cellular and plasma extraction. Hence less blood volume is processed at lower blood flow rate thereby reducing the complications associated with the procedure.
Indian market is dominated by three manufacturers namely Fresenius Kabi, Terumo Penpol, and Haemonetics. Apheresis devices available in India are either based on intermittent flow or continuous flow centrifugation.
One of the most attractive features of the newer machines is that they give cleaner products; contaminants’ such as red blood cells are minimal. Best yield of the desired product is obtained in lower volumes and in the shortest time which also facilitates storage.
COVID-19 has a surprisingly positive impact on the growth of the apheresis market in India. As of now all treatments for COVID-19 are on an experimental basis and convalescent plasma for COVID-19 has shown promising results in various trials worldwide. Increased focus of the government on plasma therapy has provided the necessary stimulus for the apheresis market including the remote areas of the country.
The coming years will continue to see an increase in indications of apheresis treatment; thereby leading to increase in components collected by apheresis and treatment of patients. Use of stem cells is unlikely to recede as more transplantation occurs across the globe to treat a greater number of malignancies. Furthermore, the emergence of immune therapies requiring cells to be engineered to treat a malignancy will lead to an even greater number of procedures.
As a result, there is reason for optimism that apheresis will remain one of the strongest treatment modalities in the future.
