Spokane, Washington, United States
|Creation in a test tube. Photo courtesy of Pixabay.|
Sarah Smith* thought today would be like any other day. She would take her kids to school, then go to her job as an office secretary. But Sarah never made it. Passing through an intersection, Sarah’s car was hit when another driver ran a red light. Paramedics arrived at the scene where Sarah was rapidly losing blood. Unfortunately, a blood shortage and lack of shelf-life stability meant that no blood was on hand for an immediate blood transfusion. Sarah did not survive.
Blood shortage is a crisis, one exacerbated by donated blood being shelf stable for only about one month. The Red Cross has been trying to keep up with the demand for blood donations, but supplies still fall short. One proposed solution is using artificial blood.
Finding a blood substitute has been a goal for centuries, beginning with unsuccessful attempts with materials such as milk and animal plasma. It was not until the late nineteenth century that a truly viable solution was created, called Ringer’s solution, a reagent still used as a blood expander today.1 During the twentieth century, artificial blood experiments included a galactoso-gluconic acid based solution around the time of World War I, extracted plasma donated from humans during World War II, and the adaption of perfluorochemicals (PFC) in the 1960s.1 These had varying degrees of success, but eventually it was determined that focusing on one specific purpose might be the key for temporary blood transfusions. In recent years, scientists have been working to produce a synthetic blood whose primary function is to carry oxygen, mimicking the job of red blood cells.
Artificial blood today can be manufactured from adult human blood, umbilical or placental blood, or from cow blood. These are classified as hemoglobin-based oxygen carriers (HBOCs) and involve modifying the hemoglobin in the donated blood into a more stable structure. One of the main obstacles scientists have to overcome with this procedure is that pure hemoglobin has very toxic effects in the body, effects that are normally neutralized by surrounding the hemoglobin with the rest of the red blood cell. In order to overcome this problem, Dr. Allan Doctor from the University of Washington developed a blood substitute called ErythroMer, which is purified human hemoglobin surrounded by a synthetic polymer.2 The polymer protects the body from hemoglobin’s toxic effects, keeping it from degrading into toxic elements. ErythroMer can be stored as a freeze-dried powder, which makes it available in hot and hostile climates such as war zones, where soldiers die from blood loss in the field at alarming rates.
Scientists in Britain announced in 2015 that they had devised a technique for growing red blood cells by extracting stem cells from donated human adult or umbilical cord blood and growing them in culture. While promising, that method produced relatively low numbers of cells and still required multiple donations. Fortunately, by 2017 the procedure was improved upon. Using similar principles, the University of Bristol and NHS Blood and Transport devised a protocol to manufacture greater quantities of an immortalized erythroid cell line. Erythroid cells are a type of immature red blood cell that can be stored for long periods of time and cultured into mature red blood cells as needed.3 These methods avoid the toxicity problem by creating fully formed red blood cells that naturally have a protective coating around the hemoglobin.
There are currently no FDA approved artificial blood products available, but there are several unapproved ones becoming available for emergencies. These include Hemopure, from a Pennsylvania company that currently markets it for transporting organs but is approved as an artificial blood source in South Africa. Hemo2Life is also used for organ transport in France, and a product called Fluosol has been approved as a blood substitute in Russia since 1997.4 These are just a few examples of artificial blood products already in use. Many scientists and researchers hope to use these products as evidence to obtain more funding for a federally approved artificial blood supply.
If the products already exist, why are they not being approved? The historic toxicity of the HBOCs ended or prevented many subsequent clinical trials. As mentioned, researchers have been working on ways to render the oxygen carriers safe, but that history has stigmatized further work. The FDA has not given up on the idea entirely, though, and proposes to study the hemoglobin pathway and HBOCs while searching for a safe and effective artificial blood product.5
HBOCs are not blood type specific so they can be used for anyone. This is most important for those with rare blood types, and even more so for those with a rare blood type and a disease that requires frequent blood transfusions. Even without a rare blood type, many products are currently being marketed for those who require frequent blood transfusions as it helps to prevent blood shortages. It also eliminates the risk of transmitting infectious diseases such as hepatitis or HIV.
Doctors, scientists, and organizations like the Red Cross maintain the need for blood donations, but expanding options for artificial blood may help to prevent tragedies like Sarah Smith from being commonplace.
*Sarah Smith is meant as a representative of many times where similar situations occur and does not indicate a real person.
- Sarkar, Suman. “Artificial Blood.” Indian Journal of Critical Medicine 12, no. 3(2008): 140-144. doi: 10.4103/0972-5229.43685
- Gammon, Katherine. “The Long Quest to Create Artificial Blood May Soon be Over.” NBCNews. January 19, 2017. https://www.nbcnews.com/mach/science/long-quest-create-artificial-blood-may-soon-be-over-n708576.
- “Major breakthrough in the manufacture of red blood cells.” NHS. March 24, 2017. https://www.nhsbt.nhs.uk/news/major-breakthrough-in-the-manufacture-of-red-blood-cells/.
- Notman, Nina. “Red blood cell substitutes.” Chemistry World. February 16, 2018. https://www.chemistryworld.com/features/artificial-blood/3008586.article.
- Alayash, A.I. “Evaluating the Safety and Efficacy of Hemoglobin-based Blood Substitutes.” March 22, 2018. https://www.fda.gov/vaccines-blood-biologics/biologics-research-projects/evaluating-safety-and-efficacy-hemoglobin-based-blood-substitutes
KELSEY RUUD is a technical assistant focused on cancer research studies who likes to write in her spare time. She has one published children’s novel and several scientific articles out for review.