Carbon monoxide is often called the “silent killer” because it is odorless and invisible, and can enter the body without being noticed. CO builds up in poorly ventilated spaces, leaks through faulty gas heaters, or is released when natural gas and propane are burned, such as on stoves. It is also a major component of smoke from fires. When CO enters the bloodstream, it latches onto red blood cells, blocking oxygen delivery to the brain, heart, and other organs. CO binds to hemoglobin 200 to 400 times more effectively than oxygen, which can cause unconsciousness and permanent damage in minutes.
Each year in the United States, about 50,000 people seek emergency room treatment for CO poisoning, and about 1,500 cases are fatal. Treating the poisoning is a race against time to quickly rid the blood of trapped CO. Currently, the only treatment available to those who make it to the hospital is to pump pure oxygen into the body, often using a hyperbaric chamber. This process is slow: It can take an hour or more for the CO to be cleared from the blood. If the patient survives, there is a risk of serious heart or brain damage.
The new therapy is based on a protein called RcoM, found in the bacterium Paraburkholderia xenovorans. In nature, it responds to trace amounts of CO in the environment. The researchers modified it to be used to remove CO from human blood. In doing so, the protein selectively binds to carbon monoxide, leaving oxygen (O₂) and nitric oxide (NO), which regulates blood pressure in the body, unaffected.
Experiments in mice showed that the drug, called RcoM-HBD-CCC, removed CO from the blood in minutes. Half of the carbon monoxide molecules were eliminated in less than a minute, allowing hemoglobin to resume carrying oxygen.
Other protein-based drugs bind not only to CO but also to vital NO, causing vasoconstriction and increased blood pressure. RcoM-HBD-CCC selectively absorbs only carbon monoxide and has almost no effect on the body. This makes it a promising rapid antidote that can be administered both in the hospital and in the field.
Although the research is still in the preclinical stage, scientists see huge potential. In addition to treating carbon monoxide poisoning, RcoM-HBD-CCC could find use in severe anemia or hemorrhagic shock.
