Overview

Transfusion Medicine (TM), commonly known as Blood Bank, has undergone a huge advancement in the last few decades. It would be fair to call Transfusion Medicine the backbone of the hospital since it provides support to surgeries, transplants, trauma patients, routine transfusion support in dialysis, chronically transfused cancer patients etc.

Transfusion Medicine has diversified from a laboratory-based approach to a patient-centred clinical speciality. Modern transfusion medicine not only deals with the blood components, its storage & issue, but it has evolved into a multidisciplinary approach encompassing various other specialities & super specialities in terms of life-saving therapeutic procedures.

The clinical TM deals with therapeutic procedures collectively known as “Apheresis”. The term Apheresis means “to take away”. This process uses a centrifuge that separates the blood into its components by density. It is a broad term which is applicable to any procedure that involves removing whole blood from a donor or patient and separating the blood into discrete components so that one specific component can be removed. Therefore, for a donor, it may be used to collect a particular blood component such as WBC, platelets or plasma while for a patient, one or more blood components can be removed to treat a disease. 

All apheresis procedures involve directing the blood in the patient/donor's veins through tubing to an Apheresis machine that separates the blood components. The separation is done by either a centrifuge process on the blood in the machine. After the separation, the desired component of the blood is removed, while the rest of the blood components are reinfused back into the patient/donor. The entire procedure is painless which is definitely an added advantage. After removing a blood component, the remaining blood components are then returned to the bloodstream of the patient/donor.  

Cellular therapy is a recent field of increasing interest in transfusion medicine. It includes-

1. PERIPHERAL BLOOD STEM CELL COLLECTION (PBSC)

Stem cells are immature cells from the bone marrow that can turn into mature red blood cells, white blood cells, or platelets. Two of the most common types of stem cell transplants are autologous and allogeneic transplants. 

An Autologous transplant uses a patient’s own stem cells. In this procedure, stem cells are collected from the patient and reinfused into the patient to help produce healthy red and white blood cells and platelets.

An Allogeneic transplant uses stem cells from a donor whose human leukocyte antigens (HLA) match with the patient. Such stem cell donors may be related to the patient, or they may be an unrelated volunteers found through a donor registry (Matched Unrelated Donor). Both kinds of stem cell transplantations are common treatment options for cancers such as leukaemia, lymphoma, multiple myeloma etc.

These patients often require intensive chemotherapy that can destroy their bone marrow and prevent them from creating enough blood cells. Stem cells normally circulate in the blood in very small quantities and can be collected from the blood through a small catheter inserted into a patient/donor’s vein.

The department of TM deals with the collection of these stem cells from the blood using the Apheresis machine. The stem cells thus collected can restore the normal cells of the bone marrow. These cells are collected into a bag and the rest of the blood is returned to the patient/donor. 

Today, essentially all stem cell transplants are performed by this method since it is associated with less pain & discomfort to the patient/donor with rapid recovery of blood cell counts in such patients. 

Peripheral blood stem cell collection is a safe procedure but just like any other medical/surgical procedure, it is not devoid of side effects. Nevertheless, it is often lifesaving for patients with blood cancer and other serious blood disorders.

This procedure is most commonly used for cancers of the blood system. It can also be used to treat other diseases of the immune system.

1. Platelet Depletion- It may also be used to reduce severe thrombocytosis (increased platelet count above normal) & prevent serious complications like heart attack, kidney failure or stroke etc. 
2. White blood cell depletion- is a medical condition known as leukocytosis (increased WBC count) in Acute Leukemia patients that can impair blood flow to the brain, lungs, eyes and other sites, and also cause damage to small blood vessels. TM specialists can effectively reduce the high load of WBCs in such patients &thus prevent complications.
3. Therapeutic Plasma exchange- TPE specifically refers to the removal of plasma from a patient and replacement with donor plasma/ Albumin. It is typically indicated in patients having autoimmune conditions like Myasthenia Gravis, Guillain –Barre syndrome, Multiple sclerosis, SLE, TTP; ABO incompatible Renal or Stem cell transplantation, poisoning etc.

Donor apheresis –

The process of apheresis has become essential in providing blood components for therapy. A volunteer donor will undergo apheresis to supply specific components. Donors can give platelet or plasma via this mechanism more often than they can donate whole blood.

Examples include:

• Plateletpheresis or Single donor platelet apheresis (SDP): this is the most common means of supplying platelets to patients who have low platelet count. Patients with Dengue, ITP, Aplastic anaemia or other types of blood cancer often require platelet support.
• Plasmapheresis: the plasma can be removed from a healthy donor to supply plasma containing clotting factors. 
• Granulocyte collection- Collection of granulocyte concentrates (a type of WBC) for patients with low granulocyte counts who have severe & often lethal infections. In such cases, granulocytes can be harvested from a donor to help fight infection in such patients.

In the due course of time, the following procedures will also be started –

1. Cryopreservation of stem cells- after the stem cells are collected by the above-mentioned technique, these cells can be stored at very low temperatures to prevent cell death. This method also provides long-term storage of stem cells for at least 8-10 years at very low temperatures while preventing microbial contamination. Besides this, the Red blood cells of a rare blood group person can also be cryopreserved.
2. Red Blood Cell Exchange- Removal of defective RBCs and substituting them with healthy & normal RBCs in patients with Sickle cell disease.
3. HLA typing- Human leukocyte antigen typing to match patients & donors for stem cell transplantation to ensure the safety & suitability of the transplant.
4. Immunoadsorption – it will be exclusively used for patients having autoantibodies or to prevent organ transplant rejection in ABO incompatible transplant patients.

Chimeric Antigen Receptor-T cell therapy (CAR T-CELL) - It is a breakthrough in the treatment of cancer where the patient’s own immune cells will be engineered to fight against cancer especially those patients with leukaemia & lymphoma. It is an upcoming technology which has the potential to cure cancer.