Immobilized Neuroglobin Scavenges Carbon Monoxide From Circulating Carboxyhemoglobin

Carbon monoxide (CO) poisoning is responsible for around 50,000 emergency department visits per year in the United States alone. Currently, there is no available antidote for CO poisoning. We have previously developed an antidotal therapy based on an engineered hemeprotein, human neuroglobin (Ngb-H64Q-CCC). Intravenous infusion of Ngb-H64Q-CCC removes CO from circulating red blood cells and improves survival in a lethal CO poisoning mouse model. However, the infusion of heme-containing proteins has inherent heme toxicity risks that may limit the dose that can be used safely without liver or kidney toxicity. To overcome these problems, we have investigated the development of immobilized Ngb in a solid matrix. This approach allows for the development of a CO removal system using an extracorporeal blood-circulating system coupled with a stationary matrix with immobilized Ngb-H64Q-CCC. Such a system avoids drug infusion and possible organ injury, allows for antidote recycling, and provides advantages for storage and handling of the antidote. Here we have developed Ngb-H64Q-CCC covalently bound to N-hydroxysuccinimide agarose. The immobilized protein shows preserved heme redox activity and retains its CO removal capacity after successive regeneration cycles. We expect that this novel approach will advance the development of new scavenger-based therapies for CO poisoning.