Research Units are designed to provide clear summaries of results and impacts of research conducted at Canadian Blood Services. Written by Canadian Blood Services researchers in collaboration with the knowledge mobilization team, these summaries will help in further disseminating research findings to facilitate informed decision-making.
Immune thrombocytopenia (ITP) is a blood disorder characterized by bleeding due to a shortage of platelets. The symptoms of ITP are highly variable, ranging from tiny bruises to life-threatening brain hemorrhages. Identifying ITP is difficult because there are no specific diagnostic criteria or biomarkers, apart from a low platelet count with no apparent other causes.
Maintaining a sufficient inventory of blood products for patients in need is of critical importance. The supply of Type O red blood cells is especially important because these “universal donor” products can be safely transfused to patients of any ABO blood type. This makes Type O red blood cells critical for emergency transfusions when the recipient’s blood type is unknown, or if there is an insufficient supply of ABO-matched blood products available for a patient in need.
The immune system includes an army of white blood cells that help protect the body from foreign invaders. A T cell is a type of white blood cell that plays a central role in the body’s immunity. T cells recognize and react to foreign markers on bacteria and viruses as well as non-self tissues and organs and thus are a significant barrier to successful transplantation of organs and tissues.
Fetal and neonatal alloimmune thrombocytopenia, or FNAIT, is a life-threatening disease affecting approximately 1 in 1,000 live births, but what is it? To break down its name: fetal and neonatal – affecting newborns and babies still in the womb; alloimmune — an immune response from the mother against the baby; thrombocytopenia – resulting in low platelet counts. FNAIT is characterized by severe bleeding, brain hemorrhage, growth restriction and, in some cases, death of the fetus or newborn. The bleeding symptoms are explained by the low platelet counts and other identified factors, but it is not yet clear why FNAIT results in growth restriction or miscarriage.
Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-related death. This rare but serious transfusion reaction is characterized by severe respiratory distress within six hours of receiving a transfusion. Currently, there are no treatments available other than supportive care (oxygen and lung ventilation).
Platelet concentrates (PCs) are derived from blood donors and consist of platelets suspended in plasma. PCs are transfused into patients with bleeding disorders. The greatest safety threat involved with PC transfusion is bacterial contamination. Staphylococcus epidermidis, a bacterium normally found on human skin, is the main PC contaminant. S. epidermidis can stick to the inner walls of PC storage bags, forming attached bacterial colonies known as biofilms that prevent detection of the bacteria during routine PC bacteria screening performed on a small sample of the liquid product. Approximately 1 in 3,000 PC units are contaminated with bacteria.
Platelets are important for controlling bleeding and healing wounds. Platelet transfusions can restore normal platelet levels in patients who have platelet disorders or who have undergone hemorrhaging or chemotherapy. One of the major problems in transfusion medicine is the bacterial contamination of platelet units, which causes transfusion reactions, sometimes with fatal outcomes. Bacteria that are normally found on the skin are the main contaminants.
Hematopoietic stem cells (HSCs) present in our bone marrow generate all the cells of our blood system. Throughout our lifetime, they continuously generate our red blood cells, white blood cells and platelets. HSCs can be isolated and transplanted to save the lives of patients with some types of cancer or blood disorders. After transplantation, HSCs settle (engraft) in the recipient’s bone marrow, where they begin to proliferate and generate the cells of the hematopoietic system to replace the defective or malignant cells that were originally there.
There are three ways to collect HSCs for transplantation. The two most common ways are collecting from the bone marrow or whole blood of an adult donor. HSCs can also be collected from the cord blood that remains in the umbilical cord and placenta after birth. There are several advantages to using HSCs from cord blood, including availability (umbilical cord blood is usually discarded after birth) and flexibility: because the immune cells in cord blood are less mature, a patient who is unable to find a matching adult donor may be able to find a matching cord blood unit.
Blood clots are necessary to control bleeding; however, too much clotting can be harmful. Heart attacks and stroke, which are leading causes of death around the world, are often caused by clots blocking the flow of blood to the heart and brain.
Blood clots in the body are normally broken up by the clot-dissolving enzyme, plasmin. Plasmin is generated when its inactive form, plasminogen, is activated by an enzyme called tissue plasminogen activator (tPA). Nearly three decades ago, tPA produced in the lab (recombinant tPA; rtPA) was developed as a drug to treat and dissolve potentially harmful clots. Despite saving many lives, rtPA sometimes causes internal bleeding because to be effective it must be given at a very high dose compared to the amount of tPA that is normally in the body. As a consequence, plasmin gets generated throughout the body and not just at the clot location where it is needed.
After blood is collected from donors, red blood cells are isolated from the blood and stored at 4°C in a solution containing anti-clotting agents and nutrients. This allows the cells to survive for several weeks (up to 42 days) before transfusion. Red blood cell transfusions help save lives at risk due to severe blood loss, low red blood cell levels as a result of chemotherapy, or diseases related to dysfunctional red blood cells.
During storage, red blood cells remain biologically active and gradually use up their energy stores. The red blood cell membranes become more fragile, and some cells burst, releasing their contents into the storage bag. These accumulated changes are referred to as the “storage lesion”. However, it is unclear whether these cellular changes have any effect on transfusion outcome.
For general enquiries about research at Canadian Blood Services, please contact us at:
