from “The Bizarre Quest for Artificial Blood”
By Jacqueline Adams
Read the text, and then answer the questions.
Picture yourself in a hospital about to undergo surgery. Your doctor enters the operating room with a live goat. In 1878, Joseph Howe, a physician in New York City, did just that. His patient was suffering from tuberculosis, and Howe wanted to find out if he could cure her by injecting the goat’s milk directly into her veins. Fortunately the patient survived, but not all who received this treatment were so lucky. Back in Howe’s day, some doctors thought milk could work as a replacement for human blood.
The quest for a blood substitute started in the 1600s. Over the centuries, doctors injected patients with substances such as cow’s milk, sheep’s blood, and even urine. Such treatments were not only ineffective but also quite dangerous.
Today, people with certain blood disorders or those who have lost a great deal of blood because of an injury commonly receive blood transfusions. Medical staff transfer blood provided by human donors into a patient’s body. Donated blood is often in short supply though, and only certain types can be given safely to specific individuals.
That’s why scientists are still searching for a viable alternative to human blood. And they want to make sure any potential substitute actually has properties similar to real human blood so it helps people who are ill, instead of making them sicker. If scientists succeed, many lives could be saved. But the hunt for artificial blood has turned out to be trickier than anyone imagined.
A COMPLEX FLUID
Blood is a remarkable substance. “The number of functions that blood has in our bodies is extremely large,” says Pedro Cabrales. He’s a bioengineer who is developing blood substitutes at the University of California, San Diego. Blood moves through a person’s veins, delivering nutrients to all the cells that make up the body. Blood also carries away waste, helps regulate body temperature, and transports chemical messengers called hormones between organs. And it contains white blood cells that fight off disease-causing germs.
One of blood’s most important functions is transporting oxygen. Red blood cells contain hemoglobin. This molecule binds to oxygen breathed in by the lungs, enabling red blood cells to carry it to tissues throughout the body. This process is essential to life. Cells need oxygen to produce energy—that’s why a person who loses a lot of blood might not survive without a transfusion.
But a transfusion isn’t always ideal or even possible. Donated blood requires refrigeration and has a short shelf life, so it’s not always available. All blood isn’t alike, either. Every person has one of eight different blood types, determined by molecules on the surface of red blood cells. Patients must receive a compatible blood type from a donor, or they could have a severe reaction and die.
Sometimes patients refuse a blood transfusion because it conflicts with their religious beliefs. Others don’t want transfusions because they fear contracting a disease from an infected donor. That risk is small in the U.S., where donated blood is screened for common pathogens that can make people sick. [...]
Artificial blood could solve these problems. “Blood substitutes that can be transported, stored easily for a longer period, and transfused without matching for blood type have potential as replacements for standard blood transfusions,” says Abdu Alayash. He’s a biomedical research chemist at the U.S. Food and Drug Administration in Maryland.
POSSIBLE SOLUTIONS
Artificial blood wouldn’t have to perform all the functions of real blood to save lives. In most cases, it just needs to transport oxygen until the body produces enough red blood cells to do the job.
One strategy scientists are trying is taking hemoglobin from human or animal red blood cells and using it to create substances called hemoglobin-based oxygen carriers (HBOCs). But “hemoglobin outside a red blood cell is unstable and breaks down into smaller, toxic compounds,” says Alayash. These compounds increase a patient’s blood pressure and his or her risk of heart attack or stroke.
Some researchers are looking for ways to prevent this toxic effect, while others are trying a different tactic: mimicking how other animal species’ blood transports oxygen. For example, bioengineer Cabrales and his team are making synthetic oxygen-carrying molecules inspired by earthworm blood. “These molecules have a unique structure that makes them less toxic than human hemoglobin,” he says.
Other researchers are trying to create synthetic blood substitutes out of chemicals called perfluorocarbons (PFCs). After PFCs are pumped into a patient’s veins, they dissolve oxygen from the lungs and carry it throughout the body. But in order for PFCs to work, the patient must be breathing in 100 percent oxygen. The air we normally breathe is just 21 percent oxygen. Higher oxygen concentrations can cause dangerous heart and lung problems.
THE QUEST CONTINUES
Despite these challenges, scientists have made some promising advances toward a true blood substitute. In South Africa [...] a hemoglobin-based oxygen carrier has been approved to treat patients. The U.S. permits this experimental treatment only in rare cases, since blood transfusions here are relatively safe.
When a blood transfusion isn’t possible, doctors do have options besides artificial blood. They can use devices to seal off severed blood vessels to minimize blood loss. They can inject the element iron (Fe)—the main component of hemoglobin—or hormones to boost red blood cell production. Certain fluids can increase blood volume, helping the patient’s remaining red blood cells continue to circulate and deliver oxygen.
But artificial blood remains highly sought after, and researchers are determined to succeed in their quest. “A safe alternative to blood will help a lot of people,” says Cabrales.
Adams, Jaqueline. “The Bizarre Quest for Artificial Blood.” ScienceWorld. October 21, 2019.
Question
Drag and drop the statements that show a claim the author of each text makes.
Put responses in the correct input to answer the question. Select a response, navigate to the desired input and insert the response. Responses can be selected and inserted using the space bar, enter key, left mouse button or touchpad. Responses can also be moved by dragging with a mouse.
from “The Bizarre Quest for Artificial Blood”
(1 answer)from “Blood: There Is No Substitute”
(1 answer)Both
(2 answers)
Doctors can rely on options other than artificial blood.
There are benefits that artificial blood could provide that human blood does not.
Many substances have been tested and proved unsuccessful as a human blood substitute.
Blood donors play an important role in helping patients in need of blood.
from “The Bizarre Quest for Artificial Blood”
Doctors can rely on options other than artificial blood.
Many substances have been tested and proved unsuccessful as a human blood substitute.
from “Blood: There Is No Substitute”
There are benefits that artificial blood could provide that human blood does not.