Just Add Water: Artificial Blood to the Rescue
If ultimately confirmed safe for use in humans, this nanotechnology-based product, called ‘ErythroMer’, could represent a new and innovative alternative to blood transfusions that would be especially valuable in situations where stored blood is needed, but difficult to obtain or use, such as in pre-hospital setting. The artificial cells are designed to be freeze-dried, stored for extended periods at ambient temperatures, and simply reconstituted with water for immediate use.
This year, the National Academy of Sciences estimated that 30,000 trauma deaths each year are preventable and of these, two-thirds arise from hemorrhage in the pre-hospital phase of care.
“One key goal is to advance treatment for trauma victims by initiating resuscitation at the scene,” said lead study author critical care specialist Allan Doctor, MD, pediatrics, of Washington University School of Medicine. “ErythroMer would be a blood substitute that first responders could carry with them and, when needed take it out, add water, and inject. There are currently no simple, practical means to bring transfusion to most trauma victims outside of hospitals. Delays in resuscitation significantly impact outcomes. It is our goal to push timely, effective care to patients even before the reach the hospital. ”
Studies in mice, conducted in partnership with Greg Hare, MD, PhD, an expert in rodent transfusion models at the University of Toronto, demonstrate that the artificial cells, also known as ‘nano-cytes’ capture oxygen in the lungs and release it to tissues — the main function of red blood cells — in a pattern indistinguishable from that seen in a control group of mice injected with their own blood. In rats, ErythroMer effectively resuscitated animals in shock from controlled, acute loss of 40 percent of their blood volume.
The donut-shaped artificial cells are formulated with bio-synthetic nanotechnology in partnership with Dipanjan Pan, PhD, a synthetic chemist and bioengineer at the University of Illinois at Urbana-Champaign, and are about one-fiftieth the size of human red blood cells. A specifically crafted polymer lining encodes a control system that links ErythroMer’s oxygen-binding behavior to tissue-specific changes in pH that blood cells encounter during circulation, thus enabling the ‘nano-cytes’ to effectively capture oxygen in the lungs (high pH) and then release it where most needed: in tissues with the greatest oxygen debt from shock (low pH). Tests show ErythroMer matches the oxygen capture/release characteristics of human red blood cells within 10 percent, a level the researchers say should be sufficient to stabilize bleeding patients until a blood transfusion can be obtained.
So far, tests suggest ErythroMer has overcome key barriers that halted development of previous blood substitutes, including unintentional vasodilator molecule trapping, which restricts flow by narrowing blood vessels. The team’s next steps are testing in larger animals, optimizing circulation time, metabolism and safety, scaling efficient production, and ultimately conducting in-human clinical trials. If further testing goes well, they estimate ErythroMer could be ready for use by field emergency responders within 10-12 years.
[Erythromer development has been supported by the Children’s Discovery Institute at Washington University and St. Louis Children’s Hospital, the Skandalaris Center at Washington University and the BioSTL Fundamentals Program, + updates on pending NIH/DoD grants]