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.
In Canada, red blood cells for transfusion are stored in the refrigerator at 1-6°C for up to 42 days, after which they are discarded. During storage, the cells change as they metabolize and age. This leads to accumulated degradation of their function and safety, which is seen as the cells change shape from a smooth disc to spiky sphere then a smooth sphere. This red blood cell “storage lesion” can be analyzed by laboratory tests. For example, cell shape is usually measured by experts who prepare the cells, spread them on a slide, look at them using a microscope and categorize their shape according to standard definitions, which places each cell into one of six shape sub-classes or “buckets”. These data are used to give a “morphology index” (MI) for the red blood cells. Using this traditional method, the loss of quality of red blood cells during storage has been very well characterized by researchers. However, the method is complex, time- and labour-intensive, prone to subjective bias, and limited by small sample sizes. The researchers aimed to address these limitations and come up with better methods to assess cell quality using label-free imaging and deep convoluted neural network learning algorithms.
Red blood cell (RBC) transfusion is an important treatment for some patients with sickle cell disease (SCD), one of the most common blood disorders in the world. Transfusion can reduce morbidity and mortality in patients with SCD, but it comes with risks: if donor RBCs have antigens that are not found on the patient’s RBCs, the patient’s immune system attacks the donor’s foreign RBC antigens through a process called alloimmunization. Alloimmunization puts SCD patients at risk of a haemolytic transfusion reaction (HTR), life-threatening hyperhaemolysis (rapid destruction of red blood cells) and other adverse outcomes. To minimize these risks, SCD patients are antigen matched to donors whose blood is typed for key RBC antigens through serology-based phenotyping. However, serological phenotyping is not foolproof; even when patients receive antigen-matched blood, alloimmunization rates can still reach 15% due to weak and partial antigen expression—this happens when mutations in one of the genes that code for a blood group antigen creates a variant of an RBC antigen. This study assessed whether genotyping could identify antigens not detected through serologic matching alone. By identifying differences in RBC antigen prediction and retrospectively evaluating alloimmunization-related outcomes, this study could help ensure safer transfusions for SCD patients.
Hemophilia is a genetic disorder that prevents blood from clotting normally, leading to prolonged bleeding. The two major types of hemophilia are caused by a mutation in either the F8 (hemophilia A) or F9 (hemophilia B) gene, which causes a deficiency in clotting factors VIII and IX, respectively. The severity of the disease (ranging from mild to severe) depends on the mutation or deletion observed in the F8 and F9 genes. The main treatment for hemophilia is replacement therapy, which involves injecting a patient with the missing clotting factor. This treatment can be expensive or, in lower-income countries, not available. When replacement therapy is available, serious problems associated with hemophilia A or B can be prevented and the life expectancy of the individual should approximate that of the general population.
To better understand the global burden of hemophilia, it is essential to have accurate data on the number of males with hemophilia across countries. Men are almost exclusively affected as the genes for these proteins are located on the X chromosome of which men have only one copy. The aim of this study was to accurately estimate prevalence at birth of hemophilia and life expectancy by type (A or B) and severity. Global comparisons of expected and observed numbers of patients with hemophilia can provide insights into the efficiency of healthcare systems.
Stem cell transplants are used to treat more than 80 diseases and disorders, including blood cell cancers such as leukemia. Cord blood — the blood left in the umbilical cord after a baby is born — is a rich and important source of stem cells for transplantation. The national Canadian Blood Services’ Cord Blood Bank collects, processes and freezes cord blood units. These units are available to any patient worldwide who needs a stem cell transplant and finds a match in the bank.
Before a cord blood unit that matches a patient can be released for transplantation, it must be tested for quality. To do these tests, the Cord Blood Bank uses a segment of the unit. Segments are small portions of the main unit that can be thawed separately. The results of tests conducted on thawed segments are used to make decisions about whether the cord blood unit will be suitable for transplantation. The tests count the numbers of certain types of cells. The tests also measure cell viability — the percentage of cells that can grow and divide into healthy cells to replace a patient’s damaged cells. Regulations and standards provide criteria for the number and viability of certain cells in cord blood units that must be met for the unit to be considered suitable for transplantation.
In this study, the researchers set out to improve the pre-transplant quality tests of thawed cord blood. The aim was to develop a standard approach that minimizes cell loss while maintaining cell viability, thus increasing the chance that units meet the standards and are found suitable for transplantation.
After cardiac surgery, it’s common for patients to lose so much blood that they need to replace some blood components (red blood cells, platelets, plasma) through transfusion. Excessive bleeding can happen when fibrinogen, a protein essential to the blood clotting process, is in short supply in a patient’s blood. Having abnormally low levels of fibrinogen for reasons that are not hereditary is a condition called acquired hypofibrinogenemia.
Hypofibrinogenemia is treated by replacing the patient’s fibrinogen with either cryoprecipitate or fibrinogen concentrate. Although both products come from blood plasma, they differ in purity, fibrinogen content and shelf life. They also have different storage and shipping requirements. In North America, cryoprecipitate is the most common product used, while in most European countries, fibrinogen concentrate is the preferred product.
This study examined whether fibrinogen concentrate performs as well as cryoprecipitate in patients who have cardiac surgery and require fibrinogen replacement.
When a unit of red blood cells is selected for transfusion, compatibility is determined by the blood type of the donor and the recipient, but not their sex. However, observational studies that have looked at the relationship between donor characteristics and patient outcomes suggest that identifying a compatible donor may involve knowing more than just their blood type. Research findings point to donor characteristics like sex, age and parity (the number of times a woman has carried a pregnancy to a viable stage), as factors that may affect patient outcomes after blood transfusion.
This study summarized evidence from studies that examined the impact of sex-mismatched transfusions (when a patient receives a red blood cell transfusion from a donor of the opposite sex) on patient outcomes.
Inflammation is characterized by redness, heat, swelling, pain and loss of function. It is a sign that the immune system is fighting something harmful. While helpful to fight injury or infection, excessive or inappropriate inflammation can cause disease. Inflammatory diseases include autoimmune diseases, which occur when the immune system attacks the body with inappropriate immune and inflammatory responses. Approximately 80 disorders are considered autoimmune, affecting an estimated 4.5 per cent of people. Autoimmune diseases include rheumatoid arthritis, type 1 diabetes and Crohn’s disease.
Blood type is determined by whether specific molecules (called antigens) are present or absent on the surface of red blood cells. There are over 300 red blood cell antigens and over 30 blood group systems, including the well-known ABO and Rh groups. Some combinations of antigens are far less common than others, making some blood types rarer than others. Blood is considered rare if the combination of antigens is only found in one person in 500, and is very rare if only found in one person in 1000.
At Canadian Blood Services, blood safety is paramount. At every step along the path from donor to recipient, measures are taken to protect recipients from receiving blood that contains infectious disease agents such as viruses or bacteria. Donors are screened for risk factors, blood donations are tested for infectious disease agents, and production processes and storage conditions that limit the risk are use.
Plasma is the protein-rich, fluid portion of blood. It contains proteins important for blood clotting and fighting infections. Biological drugs derived from plasma are essential, life-saving treatments for a variety of diseases. They include coagulation factors used to treat bleeding disorders and immunoglobulins, including intravenous immunoglobulin (IVIg), which are used to treat immune disorders. To manufacture these drugs, blood plasma from thousands of donations is pooled together, treated to reduce the risk of transfusion-transmitted infections, and fractionated into components that are used to manufacture biological drugs.