1. Leukoreduction

Leukoreduction of cellular blood products has become the standard of care for patients with cancer and leukemia receiving chemotherapy, and others requiring chronic transfusion therapy. By preventing febrile reactions and alloimmunization (and refractoriness), they contribute greatly to favorable patient outcomes and reduced hospital costs. Reported studies have shown that the risk of cytomegalovirus transmission may be reduced by leukoreduction. There is also increasing evidence that removing leukocytes may reduce the incidence of harmful immunomodulary effects of transfusion in surgical patients (manifest as post-op infections) and those with latent viral infections.

Until recently, bedside filtration has been the customary method of removing leukocytes from blood products. With studies showing inconsistent leukoreduction with this method and failure to remove fever-inducing cytokines that accumulate during storage, there has been a trend nationwide toward prestorage leukoreduction – where leukocytes are removed by filtration soon after collection. In this way, hospitals receive a ready-to-infuse product with an assured level of leukoreduction. This will undoubtedly eliminate most of the requests for washed red cells for patients with febrile reactions in spite of bedside filtration. Eliminating the costs of staff training, inventory maintenance, failed bedside filters, and investigation of febrile reactions results in a product that has medical and economic advantages over non-leukoreduced products.

2. Inactivation of infectious agents

a. Solvent-detergent (SD) treatment

By inactivating the major lipid-enveloped blood-borne viruses (HIV, hepatitis B and C, HTLV-I and II), this technology represents a major breakthrough in blood safety. Unlike existing strategies that rely on tests to identify known agents in donor blood, it works proactively like pasteurization of milk, killing both known agents as well as those not yet recognized. Its effectiveness has been amply demonstrated in the over 15 million doses of SD-treated clotting factor concentrates and IV immune globulin infused since 1985. This method has now been extended to fresh-frozen plasma (FFP). In Europe, where over three million units have been transfused, there have been no reports of infection with these viruses. In Norway and Belgium it has completely replaced FFP. Because it is made from pooled plasma and the solvent-detergent treatment does not affect non-lipid enveloped viruses such as hepatitis A and parvovirus, there is concern that the risk of infections with such viruses may be increased. There have been no reports of clinical disease from these agents in recipients of this product in Norway, possibly related to the high concentration of antibody to these viruses in the product. Pooled plasma, solvent detergent treated, known as "Plas+SD" in the USA and made by Vitex, was licensed by the FDA in May, 1998, and is now available through the American Red Cross.  Both Vitex and Red Cross are continuing their research into extending viral inactivation to include non-enveloped viruses.

b. Photochemical treatment

Other methods of inactivation of infectious agents in cellular blood products have been studied for some time by investigators at Holland Laboratories, ARC's national biomedical research facility in Rockville, MD, and others. Among these are a photochemical method consisting of treating the blood component with a photosensitizing dye (such as psoralen) followed by exposure to ultraviolet (UV-A) light.

This results in generation of singlet oxygen and other radicals that bind to nucleic acids of a number of infectious agents, leading to their inactivation. Cerus Corporation (Concord, CA) has applied similar methodology for treating platelets, with initial promising results. Of interest, this treatment also inactivates lymphocytes and prevents accumulation of cytokines; therefore it may reduce the incidence of febrile transfusion reactions, and perhaps help prevent alloimmunization and graft-versus-host disease. To inactivate viruses in red cells, the photosensitizing dye must be one that absorbs red light. A number of agents have been studied, the biggest obstacle being to produce viral kill without damaging the red cell membrane. Most promising so far are a derivative of methylene blue and a light-independent compound S303 (also developed by Cerus Corp.). Of interest, the latter also inactivates bacteria, including Yersinia enterocolitica, a troublesome contaminant of red cells known to cause post-transfusion endotoxic shock. All of these approaches, although promising, are still in the investigational phase.

Since the advent of the AIDS crisis, blood centers have been under great pressure to improve existing tests and introduce new tests to prevent transmission of blood-borne infections. American Red Cross has participated actively in this process, through its Transmissible Diseases Department at the Holland Laboratory and its leadership in adopting new technologies to reduce viral threats to blood safety. Over the past 10 years, within days of licensure of new tests for HTLV-I/II, HIV-1/2, hepatitis C and HIV antigen, American Red Cross had not only begun testing but replaced untested products on hospital tranfusion service shelves with units screened by the new test. In addition, investigators at the Holland Lab have played a key role in coordinating national studies on emerging threats to blood safety, such as Chagas' Disease. This is a serious blood-borne disease due to T. cruzi, common in South and Central America, and a possible threat in the USA due to blood donations by immigrants from these countries.

Although the blood supply today is very safe, there remains a small risk of infection with viruses such as hepatitis C and HIV due to so-called "window period donations" – donations made between acquisition of infection and the development of a positive result with existing tests. With the availability of nucleic acid  amplification testing ("NAT") methods to detect viral nucleic acids, it is now theoretically possible to eliminate most of these window period donations. Preliminary studies suggest the greatest reduction in window period will occur for hepatitis C. NAT includes well-known methods such as PCR (polymerase chain reaction), along with newer ones such as TMA (transcription-mediated amplification). Again, American Red Cross has been a leader in this research, working aggressively with companies who have developed these technologies to adapt them to screening of routine blood donations. On March 1, 1999 American Red Cross began a nationwide study of the effectiveness and feasibility of this methodology for screening routine blood donations, under an investigational new drug (IND) application.

1. Quality Assurance

Without a system to ensure that all blood products consistently meet all specifications for quality (safety, purity, potency, effectiveness and traceability), hospital customers could not have the confidence needed to deliver these products to patients in need. American Red Cross was the first major blood-collecting organization in the US to develop a quality assurance system that met all requirements of the FDA. Working to oversee and audit staff who collect, process, test, store and ship blood, our quality assurance team has strengthened our operation immeasurably.

2. National Testing Laboratories (NTLs)

All blood collected in the 36 regional blood centers of the American Red Cross is now tested at one of five National Testing Laboratories. By concentrating testing in a few standardized laboratories, each with state-of-the-art equipment and staffed with highly qualified and trained staff operating 24 hours a day, we are able to ensure top quality test results and rapid turnaround times. When a new test is implemented it is now much easier and faster to implement systemwide than ever before.

3. "MACS"

MACS refers to Manufacturing and Computer Standardization – a system developed in parallel with our new National Blood Computer System to ensure synchrony between operating procedures and the computer system. Our goal is to ensure that a blood product with the ARC label consistently meets our high specifications for quality, no matter where it was made.

1. Plasma proteins

Recombinant Plasma proteins

Although the Red Cross has not been directly involved in the development of these products (synthetic coagulation factor concentrates such as factors VIII and IX), they are mentioned here for the sake of completeness. The technology is adaptable to other therapeutic proteins such as albumin.

Transgenic therapeutic proteins

Researchers at the Holland Lab, under the direction of William Drohan, PhD, have pioneered the development of technologies for producing synthetic human proteins in the milk of animals. By inserting the genes for human coagulation factors (protein C and factor VIII to date) into pig embryos, they showed that the adult pigs synthesized the corresponding human proteins in their milk, which then could be purified for therapeutic use. This model can serve as a source of other therapeutic proteins, which have the advantage of virtually unlimited production, low cost and freedom from human infectious diseases. This research has led to Red Cross recently signing an agreement with a major biopharmaceutical company for further development and commercialization of these products.

2. Hemoglobin solutions

Research into finding safe effective red cell substitutes has been going on for many years, and now is being pursued mainly by biopharmaceutical companies. The two main classes of oxygen-carrying agents are stroma-free hemoglobin solutions and non-hemoglobin solutions, notably perfluorohydrocarbon emulsions. Toxicity of the latter has limited its use to support oxygen delivery during percutaneous coronary angioplasty.

Hemoglobin solutions appear very attractive, offering the advantages of a product devoid of red cell antigens, able to be virally inactivated, stored for long periods of time, and available in the field for use in mass trauma situations. However, because of its high oxygen affinity and rapid renal excretion, it requires chemical modification with crosslinking and polymerizing agents such as pyridoxal phosphate. Toxicity remains a major challenge - risks of bacterial sepsis (due to the the effect of iron on bacterial growth) and vasoconstriction due to binding of nitric oxide by the hemoglobin. A few products have reached the clinical trial stage – the most promising to date being a pyridoxalated polymerized hemoglobin solution ("PolyHeme") developed by Northfield Laboratories in Illinois. If successful, this product, and others likely to follow, may replace red cells for many of the current indications such as acute blood loss.

3. "Infusible Platelet Membranes"

By fragmenting the membrane of outdated platelets, investigators at a company in Watertown, Massachusetts extracted key hemostatic components of platelets (factor 3 and the glycoprotein 1b receptor). After a viral inactivation (heat) step and lyophilization, they infused the product into thrombocytopenic rabbits and demonstrated a reduction in the bleeding time. Cypress Bioscience has assumed further development of this product (now named "Cyplex Platelet Alternative"). In human volunteers with aspirin-induced prolongation of the bleeding time Cyplex caused shortening of the bleeding time. In thrombocytopenic patients it resulted in control of mucosal bleeding; of interest, this also occurred in 2/3 of patients refractory to platelet transfusions. To date, no significant toxicity has been observed; in particular, there were no antibodies to platelets, HLA or Cyplex.