In the 1800s, Theodore Gaillard Thomas gained a remarkable degree of renown as a gynecologist, largely due to his involvement in a peculiar medical practice: the use of milk as a replacement for blood. This unconventional approach was being explored across the United States between 1873 and 1880. Thomas was particularly vocal in his support of this method.
Back then, severe bleeding often meant death. Blood transfusions were attempted, but the process was uncertain. Medical knowledge was still about 30 years behind in understanding blood types. Patients who received incompatible blood experienced symptoms like discolored urine, itching, and in some cases, a deadly condition known as hemolytic shock, where their bodies' immune systems attacked the foreign cells.
In the search for a safer method to control severe bleeding, Thomas was convinced that milk was the solution. In 1875, he administered 175 milliliters of cow's milk to a woman who was experiencing intense bleeding after a surgery to remove her cancerous ovaries. Initially, the patient reported feeling as though her head was about to burst. She went on to develop a fever and a rapid heart rate, but made a full recovery within a week.Following this, Thomas conducted seven distinct milk transfusions, which he documented in various medical publications, and forecasted their "brilliant and useful future."
The utilization of saline solutions, which are still in use today, emerged as a considerably safer, albeit imperfect, temporary solution for managing emergency bleeding in the subsequent decade.
Nevertheless, the necessity for alternatives to blood persists. Last year, within a laboratory situated in downtown Baltimore, a white rabbit represented the most recent beacon of hope in this regard.
The rabbit was confined within a black metal cage, with a catheter directly inserted into its carotid artery. Prior to this procedure, a segment of its blood had been extracted and subsequently replaced with an experimental blood substitute known as ErythroMer. It is important to note that this substitute is not derived from milk. This innovation was the brainchild of Allan Doctor, a physician-researcher in his 61st year, who leads a team at the University of Maryland (UMD) School of Medicine. ErythroMer is constructed from "recycled" human hemoglobin—the protein responsible for oxygen transport within red blood cells to the body's tissues—enclosed within a membrane to resemble a miniature cell. The transfusion seemed to be successful in the rabbit. The animal's heart rate and blood pressure, as monitored on a small device nearby, appeared to be within normal ranges.
Dr. Thomas was as passionate an advocate for hemoglobin-based oxygen carriers (HBOCs), also known as ErythroMer and its predecessors, as he was for lacteal transfusions. It is important to note that donated blood has a limited shelf life of just 42 days. Despite this, there is a significant shortage of blood, even in developed countries with robust blood donation systems. In January 2022, the American Red Cross, which is responsible for distributing 40% of the nation's donor blood, declared the first-ever national blood crisis. This was due to a dangerously low supply, particularly of the rare O-negative blood type, which is considered the universal type. Concurrently, hemorrhagic shock, resulting from severe blood loss, claims the lives of approximately 20,000 individuals in the United States annually and 2 million worldwide.
In such scenarios, the development of an artificial "blood" could potentially address this critical shortage. In areas where access to fresh blood is limited, such as battlefields and rural regions (where the wait times for ambulances can exceed 45 minutes), ErythroMer could be administered immediately to sustain the essential oxygen supply to vital organs until the patient reaches a hospital. This freeze-dried powder is designed to remain effective for years and can be easily rehydrated by mixing it with saline, a solution that is readily available. Furthermore, ErythroMer is expected to be safe for all blood types, as its membrane does not contain the red blood cell surface proteins that are responsible for causing adverse reactions.
Presently, there exists no commercially accessible human blood substitute within the United States. "There is a significant void in our current capabilities, as we lack access to blood for individuals experiencing severe bleeding outside of a hospital setting," states the Doctor, who co-founded and currently serves as the Chief Science Officer of KaloCyte. This company is dedicated to transforming ErythroMer into a commercially viable product.
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