Portal de Periódicos da CAPES

A Century of Heparin

2019; Elsevier BV; Volume: 108; Issue: 3 Linguagem: Inglês

10.1016/j.athoracsur.2019.03.104

1552-6259

Chin Siang Ong, James A. Marcum, Kenton J. Zehr, Duke E. Cameron,

Medical and Biological Sciences

The year 2018 was the centennial of the naming of heparin by Emmett Holt and William Howell and the 102nd anniversary of Jay McLean’s discovery of an anticoagulant heparphosphatide at Johns Hopkins Hospital in Baltimore. This article discusses recently discovered historical artifacts that shed new light on heparin’s christening, including McLean’s unpublished letter written in 1950 that represents one of the most complete accounts of heparin’s discovery before his untimely death. In addition, the article describes the finding of a plaque dedicated to McLean and explores the circumstances of its removal from public display, as learned from interviews with present and former staff members. The year 2018 was the centennial of the naming of heparin by Emmett Holt and William Howell and the 102nd anniversary of Jay McLean’s discovery of an anticoagulant heparphosphatide at Johns Hopkins Hospital in Baltimore. This article discusses recently discovered historical artifacts that shed new light on heparin’s christening, including McLean’s unpublished letter written in 1950 that represents one of the most complete accounts of heparin’s discovery before his untimely death. In addition, the article describes the finding of a plaque dedicated to McLean and explores the circumstances of its removal from public display, as learned from interviews with present and former staff members. The Appendix can be viewed in the online version of this article [https://doi.org/10.1016/10.1016/j.athoracsur.2019.03.104] on http://www.annalsthoracicsurgery.org. The Appendix can be viewed in the online version of this article [https://doi.org/10.1016/10.1016/j.athoracsur.2019.03.104] on http://www.annalsthoracicsurgery.org. The term heparin was coined by William H. Howell (Figure 1A) and L. Emmett Holt, Jr (Figure 1B) at the Johns Hopkins Hospital in 19181Howell W.H. Holt E. Two new factors in blood coagulation - heparin and pro-antithrombin.Am J Physiol. 1918; 47: 328-341Google Scholar by adding the suffix -in (used to denote a type of biochemical compound or substance), to the Latin word for the liver, hepar. This name was given to a water-soluble anticoagulant “phosphatid, not previously described, … found in greatest abundance in the liver.”1Howell W.H. Holt E. Two new factors in blood coagulation - heparin and pro-antithrombin.Am J Physiol. 1918; 47: 328-341Google Scholar This linguistic morphologic derivation was intentional, to “indicate (the phosphatide’s) origin from liver,” and it follows the similar naming convention of a series of compounds that had been isolated and named, such as cephalin (a group of phospholipids from the brain) and cuorin (a group of phosphatides from the heart).2Levene P.A. Komatsu S. Lipoids of the heart muscle.J Biol Chem. 1919; 39: 83-89Google Scholar In explaining why heparin is novel and different from previously isolated substances, Holt and Howell first acknowledged Jay McLean’s (Figure 1C) efforts in the laboratory 2 years earlier and credited him with drawing attention to the existence of this anticoagulant. They wrote that McLean used a method previously published by Erlandsen to isolate cuorin and managed to obtain the corresponding nitrogen to phosphorus (N/P) ratio for cuorin. However, when McLean tried to isolate heparphosphatide using a method published by Baskoff, he did not obtain the corresponding N/P ratio for heparphosphatide (1:1.5). After McLean left the laboratory for a research fellowship in Philadelphia,3McLean J. The discovery of heparin.Circulation. 1959; 19: 75-78Crossref PubMed Scopus (151) Google Scholar Holt worked on heparphosphatides in Howell’s laboratory in Baltimore, by separating cephalin within heparphosphatide using a modified protocol to yield a water-soluble anticoagulant without opalescence. The presence of opalescence, Holt and Howell wrote, was an indication of contamination with cephalin and reduced heparin’s anticoagulant properties. The difficulty in separating cephalin and heparin was the result of their roughly similar solubilities. Repeated purifications to remove cephalin or prolonged exposure of the compound to air led to decreased prothrombotic activity and increased anticoagulant properties of heparin in preparations that contained cephalin. This new water-soluble substance, named heparin, had a consistent N/P ratio of 2.5:1, caused potent anticoagulation, and was thus distinct from the heparphosphatide isolated by McLean in 1916. Holt and Howell believed this new substance was a phosphatide because it gave reactions for nitrogen and phosphorus. In his unfinished account of this discovery,3McLean J. The discovery of heparin.Circulation. 1959; 19: 75-78Crossref PubMed Scopus (151) Google Scholar McLean wrote that he was initially interested in the prothrombotic properties of cephalin and wanted to isolate phosphatides from other organs, not just the brain. In reading the German chemical literature, he found that Erlandsen and Baskoff had extracted substances from the heart (cuorin) and the liver (heparphosphatide), in a way similar to how cephalin was extracted from the brain. For brain extracts, the end result was “almost all cephalin, but in the heart and especially in the liver it was something else which was mixed with cephalin.” McLean wrote that he made multiple batches of cuorin and heparphosphatide and tested their prothrombotic power. He noted that with the passage of time and with exposure to air, the earlier batches of cuorin and heparphosphatide not only lost their prothrombotic activity, presumably from the degradation of cephalin or the deactivation of cephalin’s prothrombotic activity, but also started to exhibit anticoagulant activity, more so in the heparphosphatide preparations than the cuorin preparations.3McLean J. The discovery of heparin.Circulation. 1959; 19: 75-78Crossref PubMed Scopus (151) Google Scholar, 4McLean J. The thromboplastic action of cephalin.Am J Physiol. 1916; 41: 250-257Crossref Google Scholar With these data in hand and having performed repeated experiments, McLean wrote that he then approached Howell and discussed the presence of a natural anticoagulant in the liver phosphatide preparation, albeit masked by cephalin, that gradually became unmasked with time. In an attempt to overcome Howell’s initial skepticism, McLean demonstrated the anticoagulant activity by adding the liver phosphatide to fresh feline blood—the blood did not clot. After multiple in vitro studies, McLean and Howell proceeded to administer this substance in vivo in dogs. In a newly uncovered letter in the Johns Hopkins Medical Archives (Appendix), McLean gave a detailed description of the in vivo canine experiments in which an intravenous injection of heparin led to uncontrolled bleeding over the femoral incision site. In a letter to Charles Best of the University of Toronto (Toronto, Canada), one of the co-discovers of insulin, McLean wrote that he never received the appropriate academic credit for his role in heparin’s discovery and the discovery of an anticoagulant in heparphosphatide.5Best C.H. Preparation of heparin and its use in the first clinical cases.Circulation. 1959; 19: 79-86Crossref PubMed Scopus (65) Google Scholar After McLean and Holt had left Howell’s research laboratory, Howell continued to pursue isolation of heparin from liver and worked to refine isolation protocols for the anticoagulant. He soon realized that “heparin” does not contain phosphorus, and therefore is not a phosphatide, but rather a complex carbohydrate. In December 1922, at the 35th Annual Meeting of the American Physiological Society,6Howell W.H. Heparin, an anticoagulant.Am J Physiol. 1923; 63: 434-435Google Scholar Howell reported on an aqueous isolation protocol for water-soluble heparin, which was subsequently published in the February 1923 issue of the society’s journal. With a Baltimore pharmaceutical company, he also commercialized this particular compound for experimental work. In 1924, he published the full protocol for the aqueous extraction of the anticoagulant.7Howell W.H. The purification of heparin and its presence in blood.Am J Physiol. 1925; 71: 553-562Google Scholar Howell discovered that the inhibitor was a complex carbohydrate rather than a phosphatide and contained glucuronic acid. He further discussed the chemical composition of heparin in a 1924 Pasteur lecture.8Howell W.H. The problem of coagulation. Pasteur Lecture 1925.Proc Inst Med Chic. 1925; 5: 139-163Google Scholar Notably, as Howell told the audience, the anticoagulant was still water soluble, free of protein, and contained no phosphorus. However, Howell continued to use the name heparin for the inhibitor because other researchers, such as Henry Best and colleagues in Toronto,5Best C.H. Preparation of heparin and its use in the first clinical cases.Circulation. 1959; 19: 79-86Crossref PubMed Scopus (65) Google Scholar had begun to adopt it. Whether this water-soluble carbohydrate form of heparin reported in 1922 was a completely new compound different from the water-soluble phosphorus-containing heparin he had already named with Holt in 1918 is not clear. Howell himself wrote in February 1924, in a letter to Frank Hartman of the Henry Ford Hospital,9Lam C.R. The strange story of Jay McLean, the discoverer of heparin.Henry Ford Hosp Med J. 1985; 33: 18-23PubMed Google Scholar that it was the same compound, but in his publication in November 1924 detailing the aqueous method to extract heparin,7Howell W.H. The purification of heparin and its presence in blood.Am J Physiol. 1925; 71: 553-562Google Scholar he highlighted that the active material in fact does not contain phosphorus, contrary to what he and Holt had previously reported in 1918.1Howell W.H. Holt E. Two new factors in blood coagulation - heparin and pro-antithrombin.Am J Physiol. 1918; 47: 328-341Google Scholar Some later authors opined that this “new heparin was strangely similar to Doyon’s 1911 water-soluble anticoagulant from peptone shock.”10Mueller R.L. Scheidt S. History of drugs for thrombotic disease. Discovery, development, and directions for the future.Circulation. 1994; 89: 432-449Crossref PubMed Google Scholar Recent chronologic narration and historical reconstructions11Marcum J.A. The origin of the dispute over the discovery of heparin.J Hist Med Allied Sci. 2000; 55: 37-66Crossref PubMed Scopus (41) Google Scholar, 12Baird R.J. Presidential address: “Give us the tools…”: the story of heparin—as told by sketches from the lives of William Howell, Jay McLean, Charles Best, and Gordon Murray.J Vasc Surg. 1990; 11: 4-18Abstract Full Text Full Text PDF PubMed Scopus (12) Google Scholar, 13Wardrop D. Keeling D. The story of the discovery of heparin and warfarin.Br J Haematol. 2008; 141: 757-763Crossref PubMed Scopus (250) Google Scholar attribute the controversy over credit for heparin’s discovery to McLean’s campaign in the middle 1940s and later. Although McLean always considered himself the discoverer of heparin,11Marcum J.A. The origin of the dispute over the discovery of heparin.J Hist Med Allied Sci. 2000; 55: 37-66Crossref PubMed Scopus (41) Google Scholar he began his campaign for credit of the discovery in the mid-1940s. It is likely that he was discreet initially to prevent controversy with Howell and his colleagues in Baltimore. After Howell’s death in 1945, however, McLean set out to claim credit for heparin’s discovery. Just 3 months after Howell’s death, McLean participated in an interview with radio celebrity Milton Cross, in which he was introduced as the “discoverer of heparin.” From 1945 to his death in 1957, McLean wrote letters to numerous scientists and physicians, compiled a monograph on heparin, conducted further heparin-related research, gave lectures to professional audiences, and assembled a biography. The campaign was largely successful because McLean convinced many of his contemporaries that he was the discoverer of heparin, or at least a co-discoverer, despite the issues regarding the naming, organic solubility, and chemical structure of heparin. At the time McLean commenced his campaign, heparin was widely recognized as a water-soluble and complex carbohydrate and thus chemically different from the heparphosphatides he had isolated in 1916 by organic extraction and from the water-soluble heparin isolated by Howell and Holt using organic extraction in 1918. McLean asserted that the preparations isolated in 1916 and 1918 exhibited anticoagulant properties because of the presence of a water-soluble carbohydrate form of heparin isolated by aqueous extraction by Howell in 1922 (Appendix, last page: “so the 1916 heparin was heparin and strong too!”). McLean even created a custom stamp espousing his views (Figure 2) to imprint on reprints (Charles Best papers, Thomas Fisher Rare Book Library, University of Toronto, Toronto, Canada) of his 1916 article.4McLean J. The thromboplastic action of cephalin.Am J Physiol. 1916; 41: 250-257Crossref Google Scholar McLean’s claim was disputed 2 years after his death by Silver and colleagues,14Silver J. Turner D. Tocantins L. Lipid anticoagulants.Prog Hematol. 1959; 2: 264-281Google Scholar who demonstrated that McLean’s heparphosphatide in 1916 was likely a combination of phospholipids, inositol phosphatides, sphingomyelin, and phosphatidylserine, all of which had anticoagulant activity.10Mueller R.L. Scheidt S. History of drugs for thrombotic disease. Discovery, development, and directions for the future.Circulation. 1994; 89: 432-449Crossref PubMed Google Scholar, 14Silver J. Turner D. Tocantins L. Lipid anticoagulants.Prog Hematol. 1959; 2: 264-281Google Scholar Another notable dissenter to McLean’s campaign was Louis Jaques,15Jaques L.B. Addendum: the discovery of heparin.Semin Thromb Hemost. 1978; 4: 350-353Crossref PubMed Scopus (18) Google Scholar who believed that McLean simply did not isolate water-soluble, carbohydrate-form heparin because McLean was studying fat-soluble phosphatides derived from the liver. Thus, Jaques concluded that McLean could not have discovered the carbohydrate-form heparin we know today. The only way McLean could have “discovered” heparin would be to redefine the term “scientific discovery,” shifting the focus from the biochemical isolation of the compound to crediting “work (that) led directly to development and application, as is true of history in general, e.g. the discovery of America by Christopher Columbus in 1492.”15Jaques L.B. Addendum: the discovery of heparin.Semin Thromb Hemost. 1978; 4: 350-353Crossref PubMed Scopus (18) Google Scholar Howell remained steadfast that he first isolated the water-soluble form of heparin. In a February 1924 letter to Dr Frank Hartman at the Henry Ford Hospital in Detroit, Michigan,9Lam C.R. The strange story of Jay McLean, the discoverer of heparin.Henry Ford Hosp Med J. 1985; 33: 18-23PubMed Google Scholar Howell wrote that heparin is “not a liver phosphatid prepared according to the findings of McLean” and it is a “substance [Howell] discovered and isolated by a method worked out by (himself) and published an account of it in the paper by Holt and [himself].”1Howell W.H. Holt E. Two new factors in blood coagulation - heparin and pro-antithrombin.Am J Physiol. 1918; 47: 328-341Google Scholar In his papers from the 1920s characterizing heparin,6Howell W.H. Heparin, an anticoagulant.Am J Physiol. 1923; 63: 434-435Google Scholar, 8Howell W.H. The problem of coagulation. Pasteur Lecture 1925.Proc Inst Med Chic. 1925; 5: 139-163Google Scholar, 16Howell W. The purification of heparin and its chemical and physiological reactions.Bull John Hopkins Hosp. 1928; 42: 199-206Google Scholar Howell did not credit McLean’s work with the anticoagulant phosphatides. Finally, in an autobiographical sketch, he listed one of his chief accomplishments the discovery of the polysaccharide blood anticoagulant, which he named heparin.11Marcum J.A. The origin of the dispute over the discovery of heparin.J Hist Med Allied Sci. 2000; 55: 37-66Crossref PubMed Scopus (41) Google Scholar Howell’s claim as heparin’s discoverer is understandable; by 1910 Howell had switched his research to focus almost exclusively on the study of blood coagulation,17Fye W.B. Heparin: the contributions of William Henry Howell.Circulation. 1984; 69: 1198-1203Crossref PubMed Scopus (11) Google Scholar and he dedicated the latter part of his life to this subject. In a 1951 biography of Howell,18Erlanger J. William Henry Howell 1860-1945.Biogr Mem Natl Acad Sci. 1951; 26: 151-180Google Scholar Erlanger noted that 34 of 38 papers written by Howell from 1909 to 1945, in the final stage of Howell’s career, dealt with blood coagulation. More recent accounts of heparin’s discovery11Marcum J.A. The origin of the dispute over the discovery of heparin.J Hist Med Allied Sci. 2000; 55: 37-66Crossref PubMed Scopus (41) Google Scholar, 12Baird R.J. Presidential address: “Give us the tools…”: the story of heparin—as told by sketches from the lives of William Howell, Jay McLean, Charles Best, and Gordon Murray.J Vasc Surg. 1990; 11: 4-18Abstract Full Text Full Text PDF PubMed Scopus (12) Google Scholar, 13Wardrop D. Keeling D. The story of the discovery of heparin and warfarin.Br J Haematol. 2008; 141: 757-763Crossref PubMed Scopus (250) Google Scholar, 19Marcum J.A. William Henry Howell and Jay McLean: the experimental context for the discovery of heparin.Perspect Biol Med. 1990; 33: 214-230PubMed Google Scholar, 20Ricci S. Agus G. Ninety years from discovery of heparin. Story of a loser.Acta Phlebologica. 2006; 7: 91-97Google Scholar generally acknowledge the controversy over academic credit. Several articles have focused on McLean’s prolonged absence from the heparin story.9Lam C.R. The strange story of Jay McLean, the discoverer of heparin.Henry Ford Hosp Med J. 1985; 33: 18-23PubMed Google Scholar, 21Couch N.P. About heparin, or … whatever happened to Jay McLean?.J Vasc. Surg. 1989; 10: 1-8Abstract Full Text Full Text PDF PubMed Scopus (12) Google Scholar A number of articles have been disparaging of McLean.9Lam C.R. The strange story of Jay McLean, the discoverer of heparin.Henry Ford Hosp Med J. 1985; 33: 18-23PubMed Google Scholar, 20Ricci S. Agus G. Ninety years from discovery of heparin. Story of a loser.Acta Phlebologica. 2006; 7: 91-97Google Scholar, 21Couch N.P. About heparin, or … whatever happened to Jay McLean?.J Vasc. Surg. 1989; 10: 1-8Abstract Full Text Full Text PDF PubMed Scopus (12) Google Scholar A plaque dedicated to McLean (Figure 3) was displayed for many years outside the Department of Pharmacology12Baird R.J. Presidential address: “Give us the tools…”: the story of heparin—as told by sketches from the lives of William Howell, Jay McLean, Charles Best, and Gordon Murray.J Vasc Surg. 1990; 11: 4-18Abstract Full Text Full Text PDF PubMed Scopus (12) Google Scholar at the Johns Hopkins Hospital, before it was taken down in the mid-2000s with “a moderate amount of intentionality” (personal communication, Philip Arthur Cole, MD, PhD, Director of the Johns Hopkins Department of Pharmacology and Molecular Sciences [1999 to 2017]), a decision influenced by the controversy surrounding credit.11Marcum J.A. The origin of the dispute over the discovery of heparin.J Hist Med Allied Sci. 2000; 55: 37-66Crossref PubMed Scopus (41) Google Scholar The discovery of anticoagulants dates back to Schmidt-Mulheim and the observation of peptone shock, which was first reported in the German medical literature in 1880.22Marcum J.A. Tampering With Nature: Empirical Methodology and Experimental Onto-epistemology. Nova Scientific Publishers, New York, NY2013Google Scholar The mechanism of peptone shock was found to be the result of release of heparin from liver mast cells in the blood circulation.23Marcum J.A. The discovery of heparin revisited: the peptone connection.Perspect Biol Med. 1996; 39: 610-625Google Scholar Subsequent efforts to purify heparin by Howell, Best and colleagues in Toronto,24Marcum J.A. The development of heparin in Toronto.J Hist Med Allied Sci. 1997; 52: 310-337Crossref PubMed Scopus (17) Google Scholar and Clarence Crafoord and Erik Jorpes of Stockholm,23Marcum J.A. The discovery of heparin revisited: the peptone connection.Perspect Biol Med. 1996; 39: 610-625Google Scholar eventually led to reduction of the toxicity of early heparin preparations, further characterization of heparin, and the recognition of its clinical utility. Heparin has been on the World Health Organization Model Lists of Essential Medicines since 1977,25The selection and use of essential medicines.World Health Organ Tech Rep Ser. 2015; (vii-xv, 1-546)Google Scholar when the first list was published, and has remained on the list since then, thus attesting to its value in modern medicine. In conclusion, the story of heparin is intriguing and has a large cast of characters and no shortage of different perspectives, by the characters themselves as well as by contemporary scientists, physicians and surgeons, and biographers, and medical historians. The intention of this narrative is to be historical and neutral, and its purpose is to celebrate surgical heritage in light of the centennial of the naming of heparin,1Howell W.H. Holt E. Two new factors in blood coagulation - heparin and pro-antithrombin.Am J Physiol. 1918; 47: 328-341Google Scholar as well as to illustrate the role of serendipity, persistence, and an open investigative mind. Indeed, the discovery of heparin is an example of complex progressive scientific discovery and its assimilation into the corpus of scientific and clinical knowledge. The authors wish to express their gratitude to Marjorie Kehoe and Nancy McCall from the Alan Mason Chesney Medical Archives of the Johns Hopkins Medical Institutions for their kind assistance and the permission to reproduce and reuse the historical artifacts discussed in this paper (Figures 1A, 1C, Figure 3, Appendix) and wish to thank Natalya Rattan and Jennifer Toews from the Thomas Fisher Rare Book Library at the University of Toronto for giving them access to the Charles Best papers and the permission to reproduce and reuse Figure 2. They wish to thank Glenda S. Barahona from the Lillian and Clarence de la Chapelle Medical Archives at New York University for the permission to reproduce and reuse Figure 1B and acknowledge Elbert Heng, who was involved in the first draft of the abstract. Download .pdf (1.08 MB) Help with pdf files Appendix 1Letter from McLean to the Jam Handy Organization, which was willing to make a film on heparin and its possible use in coronary thrombosis, copied to Dr. Shryock, the then-Director of the Institute of History of Medicine, Johns Hopkins Medical School. A search of the Jam Handy records in the Burton Historical Collection by the Archivist of Special Collections at the Detroit Public Library did not contain the original letter sent to McLean by the Jam Handy Organization. There was no information confirming the production of the heparin film. (Courtesy of the Alan Mason Chesney Medical Archives, Johns Hopkins Medical Institutions).