Darien, Illinois, United States
|From Left to Right: Gerald S Moss MD, Richard Brinkman MD, Lakshman Sehgal PhD, Robert Forest DVM. June 1975, photograph of the team with the first baboon resuscitated with stroma free hemoglobin after being bled down to a hemoglobin concentration of zero. Photo taken by the author.|
The ideal blood substitute would retain all of blood’s functions, none of its negative features, and have a long shelf life. Large volumes would be rapidly available, it could be sterilized, and it would not require typing and cross-matching. Current efforts are directed only at imitating the oxygen carrying capacity of blood since its other functions cannot yet be duplicated. These products fall into two groups: hemoglobin-based oxygen carrier (HBOC) and perfluorocarbon-based oxygen carrier (PFBOC).
Animals in the 1930s1 and human subjects in the 1940s2 had been infused with free hemoglobin. Interest waned in the 1950s after the United States Navy had terrible results in forty-seven sailors infused with hemoglobin for anemia.3 In the late 1960s the need for large quantities of blood at short notice during the Vietnam War revived interest. The head of the Army Research and Development command asked Dr. Gerald S. Moss, then Chief of Surgery at the West Side Veterans Administration Hospital Chicago (now the Jesse Brown VA Hospital), to try and develop an HBOC. Soon thereafter Dr. Moss became Chief of Surgery at Cook County Hospital and he carried out his pioneering work at the Hektoen Institute of Medical Research.
Hemoglobin obtained from human or bovine red blood cells, or from human placentas, is a tetramer with two α and two β subunits. It extravasates from blood vessels and combines with nitric oxide (NO). The resultant lack of free NO causes vasoconstriction, hypertension, capillary collapse, strokes, myocardial infarctions, and death. Hemoglobin is also nephrotoxic unless cellular debris and stroma that deposit in and obstruct renal tubules are removed by ultrafiltration. It only has an intravascular half-life of twenty-four hours as it breaks down into dimers that are rapidly cleared by glomerular filtration. Finally, because of its great affinity for oxygen, free hemoglobin is inefficient in unloading oxygen in the tissues. Moss and his team extracted hemoglobin from outdated red blood cells, cross-linked it with glutaraldehyde, pyridoxilated it, and removed all unreacted tetramer.4 This linked polymerized pyridoxylated hemoglobin was too large to leak out of blood vessels. It had a P50 of 20-22 mmHg compared to 26 mmHg of normal red cells and it was stable for a year when stored at 4-8°C. In June 1975 they successfully resuscitated, for the first time, a baboon bled down to a hematocrit of zero.
Northfield Laboratories in Evanston, Illinois was created in 1985 to transition into clinical trials with the HBOC now named PolyHeme. Phase I trials were completed in 1998.5 In forty-four trauma patients it was well tolerated and reduced the need for allogenic blood by 3.5 units. In another trial it maintained hemoglobin levels of 7-10 g/dL in 171 trauma patients during surgery, and had a 30 day mortality rate of 25% compared to 64.5% for 300 historical controls.
However, problems occurred in an Acute Normovolemic Hemodilution trial involving abdominal aortic aneurysm surgery. Ten of eighty-one patients who received PolyHeme suffered myocardial infarctions (MI) and two died, while none of the seventy-one who received blood suffered MIs.6 Northfield blamed the complications on overtransfusion due to physician inexperience with PolyHeme. The United States Food and Drug Administration (FDA) agreed and Northfield was approved for a controlled study of patients in hemorrhagic shock due to trauma, which had two primary end points: those of superiority and non-inferiority between the treatment and control groups. The upper limit of the confidence interval for noninferiority was set at 7% greater than the control.
The results7 can be summarized as follows. For the 30 day mortality, upper limit of confidence intervals for patients treated per protocol were at 6.29% whereas for those evaluated as randomized regardless of actual treatment received and those evaluated as treated were above 7%.
There were no statistically significant differences between PolyHeme and controls regarding secondary efficacy endpoints such as Day 1 mortality, incidence of multiple organ failure, use of donated blood on day 1, or analysis of mortality by mechanism of injury (penetrating or blunt). The PolyHeme group required significantly less blood transfusion than controls (41% vs 51% p[<=]0.05).
The most common adverse events in both groups were anemia, fever, and electrolyte imbalances and the most common severe adverse events in both groups were shock, pneumonia, and respiratory failure.
The lower confidence band for mortality was outside the agreed upon limit and ethicists8, 9 and the Federal Office for Human Research Protections10 objected to the lack of informed consent and continued use of PolyHeme in the hospital setting. Advocates11, 12 of the study presented counter arguments but the FDA denied permission for further trials in May 2009 and Northfield laboratory declared bankruptcy in June.
Two other HBOC products, HemAssist (Baxter Healthcare, Deerfield, IL) and Hemopure (Biopure laboratories, Cambridge, MA), also failed in clinical trials.
HemAssist was created at the Letterman Army Institute of Research (LAIR) by pooling, washing, then lysing and filtering outdated human red blood cells. Hemoglobin was deoxygenated, cross-linked with bisfumarate, and reoxygenated. Its hemoglobin concentration was 10gm/dL and P50 was 32 mmHg. Baxter Healthcare won the bid to carry out clinical trials in 1985. Since initial clinical trials had equivocal results, the Army backed out while Baxter continued with trials. In 1997 a phase III trial was started on trauma patients in the United States and Europe. In the United States 850 patients were to be recruited but the trial was discontinued within a year because mortality rates of the first 100 patients was significantly higher (46%) than that of patients given normal saline (17%). Although there were no such issues in Europe, that arm was also cancelled.13 Baxter has since exited this market.
Hemopure was produced from highly purified bovine hemoglobin polymerized with glutaraldehyde. The first-generation product caused severe gastrointestinal problems. The second-generation product is used in veterinary medicine under the proprietary name of Oxyglobin. The third-generation product (HBOC-201), developed for human use, has the highest hemoglobin concentration and the lowest oxygen affinity of HBOCs. It can be stored at a wide temperature range and has the longest shelf life. However, during initial studies in elective cardiac and infrarenal vascular surgery it appeared to impair oxygen delivery by decreasing cardiac output. The FDA did not permit a Phase III trial on trauma patients due to concerns about study design and justification for the trial.
So far, no other HBOC or PFBOC has reached the clinical trial stage in the United States.
In a 2001 interview for the Nova program “Cancer Warrior” Judah Folkman said, “Most research is failure. You go years and years and years, and then every once in a while there is a tremendous finding, and you realize for the first time in your life that you know something that hour or that day that nobody else in history has ever known, and you can understand something of how nature works.” In this field that day has yet to come.
- Amberson WR, Mulder AG, Steggerda FR, Flexner J, Pankratz DS. 1933. Mammalian life without red blood corpuscles. Science 78;106-107.
- Amberson WR, Jennings JJ, Rhode CM. 1949. Clinical experience with hemoglobin-saline solutions. J Appl Physiol 1;469-489.
- Winslow RM: Hemoglobin based red cell substitutes. 1992. The results of 62 large volume hemoglobin infusions in man. Baltimore & London. Johns Hopkins University Press. Pp 177-178.
- Gould SA, Sehgal LR, Sehgal HL, Moss GS. 1995. The development of hemoglobin solutions as red cell substitutes: hemoglobin solutions. Transfus Sci 16;5-17.
- Gould SA, Moore EE, Hoyt DB, Burch JM, Haenel JB, Garcia J, DeWoskin R, Moss GS. 1998. The first randomized trial of human polymerized hemoglobin as a blood substitute in acute trauma and emergent surgery. J Am Coll Surg 187;113-120 discussion 120-122.
- Burton TM. 2006. “Amid alarm bells, a blood substitute keeps pumping”. The Wall Street Journal, February 22, 2006 (updated on February 26, 2006).
- Northfield Laboratories reports results of pivotal Phase III trauma study [press release] Evanston, IL 2007. Business Wire; [Online] [May 23, 2007]. Available from: http://phx.corporate-ir.net/phoenix.zhtml?c=91374&p=irolnewsArticle&ID=1005951&highlight= [Google Scholar]
- Kipnis K, King NM, Nelson RM. 2006. An open letter to institutional review boards considering Northfield laboratories’ PolyHeme trial. Am J Bioeth 6;18-21.
- Holloway KF. 2006. Accidental communities: Race, emergency medicine and the problem of PolyHeme. Am J Bioeth 6;7-17.
- Burton TM. 2006. “Blood substitute study is criticized by US agency”. The Wall Street Journal, March 10, 2006, Page A3
- Moore EE. 2005. Emerging role of hemoglobin solutions in trauma care. Transfusion Alternatives in Transfusion Medicine. 6;69-77
- Dougherty AH. 2006. Letter to the editor: In defense of the PolyHeme trial. Am J Bioeth 6;W35-37 comment on Am J Bioeth 2006,6;18-21
- Japsen B. 1998. “Baxter ends trial of blood substitute. Chicago Tribune, July 24, 1998
JAYANT RADHAKRISHNAN, MB, BS, MS (Surgery), FACS, FAAP, is an Emeritus Professor of Surgery and Urology at the University of Illinois since 2000. After a Surgery Residency and Fellowship in Pediatric Surgery at the Cook County Hospital, he completed a Pediatric Urology Fellowship at the Massachusetts General Hospital, Boston. He then returned to the County Hospital and worked as an attending pediatric surgeon and served as the Chief of Pediatric Urology. Jayant continued his career at the University of Illinois, Chicago from where he retired as Professor of Surgery & Urology, and the Chief of Pediatric Surgery & Pediatric Urology. He has been an Emeritus Professor of Surgey and Urology at the University of Illinois since 2000.