One hundred years since the discovery of heparin, not so long ago. The story of a loser

Stefano Ricci, Giovanni Agus

This article is part of an issue appeared in the Journal Acta Phlebologica 2006 August; 7(2): 91-7 (by kind permission).

Introduction

The discovery of heparin dates back to 1916. In 2016, there will be the hundredth anniversary since this event which was initially considered as a curious physiological phenomenon, but subsequently became the basis for the evolution of vascular and cardiac surgery, haemodialysis, blood conservation, and prevention and treatment of thrombo-embolic disease.
Heparin discovery, its subsequent understanding, production, experimental and clinical application, and its final introduction into clinical use like a major pharmacological aid in many treatments almost resemble the script of a drama, full of joys and tears.
Jay McLean is credited (see photo and biographic reference of G. Agus elsewhere in the journal) to the first description of a natural substance acting as inhibitor of coagulation (1916). This was done in the occasion of a relatively simple biological research on the pro-coagulation activity of cephalin, a phosphatid compound of many body tissues, mostly in the brain.
McLean was a 2nd year medicine student eager to satisfy his pretension of independence and his self esteem: The discovery of heparin came as a result of my determination to accomplish something by my own ability.1
The observation of an anti-coagulating function of a fraction of a heart and liver phosphatid was mainly a serendipitous event, even if associated to logic procedures.
Later on, McLean underlined that the common opinion that he discovered this by chance was not correct. It was discovered serendipitously in the course of a problem, but not merely by chance.2 This to explain that chance, when displaying its effects must be guided in some ways by a human contribution.
Subsequently, heparin was divulgated and studied by W.H. Howell (1918), chief of the physiology department where the research was accomplished; it was licenced for production by C.H. Best (1931), a Canadian physiologist; it was clinically employed for the first time by Murray, in Canada, and by Crafoord in Sweden at the same time (1936).
More than 30 years were needed before passing from discovery to clinical use, though. All the characters of this story achieved fame and honor for their contribution in developing heparin, except for poor McLean, a real born-to-lose guy. In fact, he rapidly followed a diverting career (1917), and realized only a long time after (1940) that he had been part of an historical event, though only skimming over it.
His battle for achieving recognition as heparin discoverer had a minor result only after his death, when a bronze plaque was placed at the Department of Pharmacology of the Johns Hopkins Medical School.1
This is what the plaque reads:

Jay McLean, MD, 1890-1957. In recognition of his major contribution to the discovery of heparin in 1916, as a second-year medical student in collaboration with Professor William H. Howell. This plaque is presented to Johns Hopkins Medical School at the Conference on Bleeding in the Surgical Patient, held by the New York Academy of Sciences. May 3, 1963.

Biography of Jay McLean

Jay McLean was born in San Francisco in 1890. His childhood was unfortunate, scarred by tragic events like his father’s death when he was 4, the re-marriage of his mother five years later, and the the earthquake fire in San Francisco in 1906. Also, he had a bad relationship with his stepfather, who stopped supporting his studies when he was 22. This notwithstanding, he managed to obtain his Bachelor of Science Degree in 1914 at the University of California. Recalling those days he wrote:2

My argument was that Johns Hopkins offered me more preparation in the field of academic surgery, that is, research and teaching, for a lifetime career. Also I felt deeply the responsibility of being a physician. I doubted if I possessed the qualifications to become one; and I deliberately chose the fiercest student competition, as Johns Hopkins' matriculants were meticulously chosen.

He entered Johns Hopkins University in 1915 and met William H. Howell, chairman of the Department of Physiology, already famous at that time, with a long-lasting experience in blood coagulation research. Indeed, in 1910 he had found a way to isolate thrombin and his Textbook of Physiology published in 1905 would have gone through 14 editions.

Dr. Howell gave me the problem of determining the value of the thromboplastic substance of the body. He thought this to be kephalin (cephalin),..... It was kept in a glass vessel with ground glass cover (vaselined), as it was observed that access of air decreased its ability to accelerate clotting. In three months it was decayed. My problem was to determine what portion of this crude extract was the active accelerator of the clotting process and to that end, to prepare cephalin as pure as possible and determine if it had thromboplastic action. I was also to test the other components of the crude ether-alcohol extract. I was assigned a sink and attached table-drain board with a shelf over the sink in a large student physiology laboratory (not used as such then) across the hall from Dr. Howell's office and private laboratory.2

After one year (1916), he could send for publication to the American Journal of Physiology the following paper, below reported only in those parts concerning the findings of an anticoagulating substance.

The thromboplastic action of cephalin3

In 1912, Howell reported the results of a study of the thromboplastic action of the tissues in which he showed that the active substance is a phosphatid having the general properties of cephalin.
At the suggestion of Dr. Howell I have undertaken a re-examination of this subject to determine if possible whether the thromboplastic effect may be attributed to an impurity, or is a property of the cephalin itself, and also to determine in how far a similar property is exhibited by other related phosphatids. The phosphatids which have been examined in regard to their thromboplastic action are cephalin, lecithin, sphingomyelin, cuorin and heparphosphatid.
The cuorin, when purified by repeated precipitation in alcohol at 60”, has no thromboplastic effect-indeed it possesses an anticoagulating power as may be illustrated by the following experiment.
Dog’s oxalated plasma and dog’s serum Using-Plasma, 8 drops; phosphatid, 3 drops; serum, 3 drops. Control-Plasma, 8 drops; water, 3 drops; serum, 3 drops.
Heart cephalin.. . . . . . . . . . . . . . . . . .;.. . . . . . . . . . . . . . .solid clot 3 min.
Cuorin.. . . . . . . . . . . . . . . . . . . . . . . .;.. . . . . . . . . . . . . . .not clotted in 6 hours.
Control.. . . . . . . . . . . . . . . . . . . . . . .;.. . . . . . . . . . . . . . sliding clot in 9 min.
Cuorin added to blood fresh from the artery will delay its coagulation remarkably. Baskoff in his work on the phosphatids of the liver, succeeded in isolating a phosphatid which resembles cuorin. To this phosphatlid he gave the name of heparphosphatid.
The heparphosphatid on the other hand when purified by many precipitations in alcohol at 60” has no thromboplastic action and in fact shows a marked power to inhibit the coagulation. The anticoagulating action of this phosphatid is being studied and will be reported upon later.
Conclusions: Cephalin when prepared as pure as possible exhibits marked thromboplastic activity, as indicated by it’s effect, in increasing the thrombic action of fresh serum. The other phosphatids that have been described, lecithin, cuorin, heparphosphatid and sphingomyelin have no thromboplastic action.

In the conclusions, no mention is found about the discovered properties of cuorin and heparfosphatid to inibit coagulation.
In a letter written 24 years later, in 1940, he explained to Dr. Best in Toronto:4

[…] the Professor thought the findings were tentative and should not be included in an article on the clotting properties of cephalin, but rather should be studied further and written about in a separate paper. He finally agreed to permit its inclusion in the body of the paper, but not in its conclusions.

McLean completed his work and at the end of the year moved to Philadelphia for a fellowship at the University of Pennsylvania, further studying purification of the coagulant cephalin (1917).
He graduated in 1919, had a surgical training till 1924 in New York, when he entered private practice. Thereafter (1939 at the age of 49 years), he moved from New York to Columbus, Ohio, working as an assistant in private pathology laboratories and becoming involved in the use of radiation for cancer.
His sporadic research efforts with heparin did not obtain any important results. In 1940 heparin was already universally recognized as a fundamental pharmacological progress and now in worldwide use.
McLean, finally aware of the importance of heparin, began a campaign based on letters to the most important physiologists and on literature harvesting, with the aim of publishing a monograph and achieving recognition as the discoverer of heparin. This useless and sad campaign was vigorously pursued for 7 years.
His collection of reprints grew to monumental proportions, but the article on the discovery of heparin was never completed.
This material referred to more than 1300 numbered, abstracted, and cardboard mounted reprints, collected in an Index and Abstracts of the Heparin Literature, as well as his notebooks from 1916. The collection was sent to Toronto, where it remained for many years in the library of the Best Institute.1
His recollection of the events of 1916, although written and rewritten during the next 17 years, was published only two years after his death, in 1959.2
Ironically, the heparin of 1940 had nothing to do with the liver and was not a phosphatid: it was extracted from beef lung and was a complex carbohydrate containing sulfur, but this was not the real problem for McLean.
In his last paper – more similar to a will than a scientific paper (it was published after his death) – we can feel the atmosphere of those days and the details of that discovery.2 In this very personal report we can understand a substantial polemical position toward Howell. He also underlined his personal initiative in the research development and in finding the anticoagulant effect of some substances (although incidental):

By this time, what little cephalin remained from my former studies with brain tissue was deteriorated by the process of extraction plus air and time....I had saved batches of cuorin and heparphosphatide and from time to time tested these in serum plasma to determine whether or not the cephalin from the heart and liver deteriorated and lost its thromboplastic power as did that from the brain. If I had not saved them, I would probably not have found heparin. This was a fortuitous decision. All I was trying to prove was that an ether-soluble, alcohol- insoluble extract of cephalin would accelerate coagulation of blood, and it did.
I became interested in the deterioration of cephalin (an unsaturated fatty acid), which I assumed became saturated on exposure to air (and ether-alcohol purification. The various batches were tested down to the point of no thromboplastic activity, but two of those first prepared appeared not only to have lost their thromboplastic action, but actually to retard slightly the coagulation of the serum-plasma mixture. I had in mind, of course, no thought of an anticoagulant, but the experimental fact was before me; and I retested again and again until I was satisfied that an extract of liver (more than heart) possessed a strong anticoagulant action after its contained cephalin had lost its thromboplastic action.
After more tests and the preparation of other batches of heparphosphatide, I went one morning to the door of Dr. Howell's office, and standing there (he was seated at his desk), I said, Dr. Howell, I have discovered antithrombin. He smiled and said, Antithrombinis a protein, and you are working with phosphatides. Are you sure that salt is not contaminating your substance? I told him I was not sure of that, but it was a powerful anticoagulant. He was most skeptical.*

*(we arbitrarily underlined the sentences related to the discovery of the anticoagulation effects)

However, in 1940, in a letter to Dr. Best,5 he recalled:

While I was in Philadelphia, Dr. Howell wrote me and offered to place my name on his 1918 paper in consideration of the intravascular injection work we had done. I declined and told him I had participated to such a small extent in this later work that I did not feel I was entitled to the privilege offered; also that the work which I had done in discovering the anticoagulant action of the substance was already published in my paper of 1916 and that future work, such as the chemical purification and mechanism of its action, etc., I should be content to leave in his laboratory.6

In 1947, McLean moved from Columbus to become Director of the Bureau of Cancer Control of the District of Columbia.
In 1957, Dr. Irving Wright, who was organizing a historic symposium on heparin, asked him to write his recollection of the events of 1916. Ironically, Jay McLean was unable to complete his story before he died of myocardial ischemia on Nov. 14, 1957, at 67 years of age. His unfinished autobiographic paper was published in Circulation in January 1959 with the title The Discovery of Heparin, and is partially reported above.
Although initially sceptical, Professor Howell was strongly interested by the new anticoagulating substances and, with the assistance of another medical student, L. Emmett Holt Jr., he continued to work on the subject trying to achieve its purification. In April 1917, he delivered the prestigious Harvey Lecture in New York on the topic of The Coagulation of the Blood.7 He stated:

In some work done in my laboratory by J. McLean and published in 1916, an investigation was made of the action of the various phosphatids in regard to their influence on the process of coagulation. It was found that phosphatids from the heart and liver.., have a marked inhibiting effect upon coagulation.7

Heparin was named by Howell for the first time in Two New Factors in Blood Coagulation. Heparin and Pro-Antithrombin (1918), submitted to the American Journal of Physiology:6

The first new factor is a phosphatid not previously described, which exists in various tissues but is found in greatest abundance in the liver. This phosphatid is designated as heparin to indicate its origin from the liver. It inhibits coagulation partially or completely, according to the concentration... Attention was first called to this substance during some work done in this laboratory by Jay McLean in the course of his work.

In 1923, the product was no more an ether but an aqueous extraction, 5 times more effective than the initial.
It was licensed for commercial production by Hynson, Westcott and Dunning (H, W & D) not for clinical use, but [...] as an aid to laboratory workers who need an effective anticoagulant in their experimental work.8
Nevertheless, some clinical thoughts were already in the air at the Johns Hopkins Hospital. Although no patient had ever received a direct injection of heparin, it was used as an anti-coagulant for blood transfusions to six patients, two of whom developed toxic reactions.
Howell continued to work on dog liver trying to obtain a purified heparin and retired in 1930 at the age of 70 years, leaving the research activities, but very busy in revising the fourteenth edition of his famous textbook. He died of a myocardial infarction at 85.
A clinically useful form of heparin was introduced in Canada and Sweden in 1937. Simultaneously, Crafoord9 and Murray10 published their first clinical experiences. Heparin became available in the USA only in 1940, 34 years after its descovery.

References

1. Baird RJ. "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;11:4-18.[Pubmed]
2. McLean J. The Discovery of Heparin. Circulation 1959;19;75-78.[Pubmed]
3. McLean J. The thromboplastic action of cephalin. Am J Physiol 1916;41:250-7.[Full-Text]
4. Best CH. Preparation of heparin and its use in the first clinical cases. Circulation 1959;19;79-86.[Pubmed]
5. Best CH. Collected papers and correspondence. Toronto: University of Toronto. Cited by Ronald J. Baird
6. Howell WH, Holt E. Two new factors in blood coagulation--heparin and pro-antithrombin. Am J Physiol 1918;47:328-41.[Full-Text]
7. Howell WH. The coagulation of the blood. Harvey Lect 1916-1917;12:272-323.
8. Howell WH. Heparin, an anticoagulant, preliminary communication. Am J Physiol 1923;63:434-5.
9. Crafoord C. Preliminary report on postoperative treatment with heparin as a preventive of thrombosis. Acta Chir Scand 1937;79:407.
10. Murray DWG, Jaques LB, Perret TS, Best CH. Heparin and the thrombosis of veins following injury. Surgery 1937;2:163.

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