With an $11M grant, BIDMC hematologist Bruce Furie, M.D., is putting the clot on the spot
Bruce Furie, M.D., believes that blood clots, despite their obstructive power, don’t get the attention they deserve. As a preeminent authority on thrombosis, the process by which they form, he should know. “What’s the number one killer of people? Heart attack and stroke — and that’s thrombosis,” says Furie. “These diseases kill more people than all types of cancer combined, but for reasons that I do not understand, this field is not attracting much attention and effort at academic centers today. There are only a handful of us that do thrombosis-related research at Harvard Medical School, and yet it is so relevant to major clinical problems.” As chief of the Division of Hemostasis and Thrombosis at BIDMC, Furie has done his share to change that situation. Not only has his lab worked tenaciously to understand the mechanisms that underlie blood clot formation for the last 40 years, but he has also dedicated himself to training an ever-expanding pool of pre- and postdoctoral fellows so that the groundbreaking work he has started in this area will continue at the medical center and beyond.
Ironically, Furie himself did not begin his career in hematology, the study of blood and related diseases, but in protein biochemistry, with a particular focus on how proteins are structured and function. But during medical school, from his work both in the clinic and the lab, he made the connection between protein chemistry and blood coagulation, a link that has carried through his innovative research ever since. Furie and his team have made pioneering discoveries in understanding the role of vitamin K in the synthesis of certain blood clotting proteins. They discovered P-selectin, an adhesion molecule that serves as “molecular Velcro” to capture critical white blood cells at the site of inflammation. They were the first to crystallize and determine the structure of factor VIII, the protein missing in the blood disorder hemophilia, and in collaboration with BIDMC scientist Mingdong Huang, Ph.D., have crystallized eight more proteins involved in coagulation. But perhaps most exciting was their creation of a unique piece of technology that Furie calls “the lifeblood of my lab,” which pulled him into the world
of animal models and ultimately led to an $11 million National Heart, Lung, and Blood Institute (NHLBI) grant to further fuel his work.
This technological marvel, called a widefield and confocal digital video intravital microscopy system, came about as Furie’s team was looking at a certain protein that promotes the interaction of white blood cells and platelets. They realized that the ideal way to get an answer about the protein’s function was to create a knockout mouse, a mouse which researchers genetically engineer to “knock out” the activity of a particular gene, with sometimes lethal results. “No one told me if your knockout mouse survives, you have to study mice,” chuckles Furie, who had found himself in the unusual position of needing to be able to see the effects of the gene manipulation in a live animal. The problem was nothing existed that could sufficiently overcome this obstacle. Furie’s solution? Create something himself. The novel microscopy system he and his colleagues built now allows his team to image and analyze blood clot formation in a living, anesthetized mouse. “The whole concept of how blood clots form emerged over the years from using purified proteins and purified cells in test tubes,” says Furie. “Then suddenly, we could study this process as it was happening in an animal and look at all the components in their natural habitat. It provided a new perspective.”
That the game-changing system even exists underscores the concept that persistence pays off and showcases the importance of seed funding to pursue more out-of-the-box research ideas. “The big problem we had with our microscope is that the NIH (National Institutes of Health) is very risk-averse,” recalls Furie. “When I put in a grant for the microscope, they said, ‘This can’t be done. This belies reality. You can’t do this on a live mouse.’ And they gave 55 reasons. But, with some discretionary money, we built it ourselves. Now, all of our grant funding is derived from studies with this microscope. It is the centerpiece of our research right at the moment.” Ironically, once Furie’s team firmly established the microscope’s potential in this area and made a groundbreaking discovery with it, the NHLBI at the NIH designated BIDMC as a Translational Research Center in Thrombotic and Hemostatic Disorders, which comes with a five-year, $11 million award. BIDMC was one of only five institutions in the country to receive this type of funding.
The NHLBI award is allowing Furie’s laboratory to build upon its novel—and quite accidental—discovery that protein disulfide isomerase (PDI), which is essential for protein synthesis in cells throughout the body, is a critical player in blood clot formation. While studying another protein pathway that was “unproductive,” Furie found that, when using a laser to stimulate an injury to a blood vessel in a living mouse, PDI is rapidly released from both platelets, which circulate in the blood, and endothelial cells, which tile the blood vessel wall. “Sometimes you just have to follow your nose,” recalls Furie. “Using our microscope, we could actually see, for the first time, that PDI is secreted from the cells in the blood vessel during clot formation. After demonstrating that this PDI was absolutely required for the generation of a thrombus, it became clear that PDI outside the cell might be a potential target for thrombus prevention.”
With finding a new class of antithrombotic agents as the ultimate goal, Furie may just have lit upon an option that is potentially more effective than any other developed for treating blood clots before. Clots, which occur in both arteries and veins, develop in one of two ways. Clots in arteries, which lead to strokes and heart attacks, are rich in platelets; venous clots, which cause deep-vein thrombosis and pulmonary embolism, are rich in fibrin. While certain drugs on the market today work by impeding platelet clot formation (most notably aspirin and clopidigrel [Plavix]) and others work by hampering fibrin production (such as warfarin [Coumadin] and heparin), no single agent currently exists to act on both types of clots. But PDI inhibitors may well fill that void. “We have discovered that the inhibition of PDI can work in both scenarios, affecting both platelet thrombus and fibrin formation,” says Furie. “It’s a whole new approach to antithrombotic therapy.”
Pursuing the promise of this lead, Furie—in collaboration with BIDMC investigators Barbara Furie, Ph.D., his wife and longstanding research partner, and Robert Flaumenhaft, M.D., Ph.D., one of his former fellows who is now an established independent investigator—subsequently established that a bioflavonoid called rutin is an inhibitor of PDI. Rutin is a naturally occurring compound found in fruits, vegetables, and teas and is sold over the counter as a supplement. “We really lucked out,” notes Furie. “This compound is available at your local drug store. You can buy it off the shelf. We eat it all the time. And it completely inhibits thrombus formation in the mouse.” Part of the NHLBI funding will go toward three separate clinical trials to test the efficacy of rutin and other similar PDI inhibitors in humans. The project, which will be conducted in collaboration with BIDMC hematologist Jeffrey Zwicker, M.D., will also include a pharmacokinetic study to determine optimal methods
of drug delivery.
But being the biochemist that he is, Furie is also determined to get to the heart of what makes PDI inhibitors tick. “Some of our best drugs have been around forever, and no one has any idea how they do what they do,” says Furie, who is now busily trying to raise funding for functional studies of these protein pathways. “But I just can’t imagine using a new agent without having an understanding of what it’s doing or how it works. So we can prevent blood clots but what are these enzymes really doing? How do they work mechanistically? That is what this is all about.”
Furie points out that uncovering safe and effective agents to prevent blood clots and understanding how they function could not only reduce the impact of the leading killers of heart attack and stroke but also significantly alleviate other major medical problems. With the help of the NHLBI award, his team will soon be embarking on a large clinical trial to try and prevent cancer-induced thrombosis, which is the second leading cause of death in patients with the disease. He and his colleagues have also received grants from the Lupus Research Institute to study the development of blood clots related to this chronic autoimmune disorder.
The broad applications of his specialty is one reason why Furie is passionate about mentoring others to follow in his footsteps. “We’re going to have a shortage of hematologists very soon because my generation is going to die off, and we’re not training anyone to do benign hematology,” he says, noting that the field is often clumped together with oncology. “And that’s a real problem.” It’s a problem that Furie has done his part to solve, having trained more than 110 pre- and postdoctoral fellows in his laboratory over the years. But he strongly feels that it’s an area that could use some philanthropic attention. Furie believes a continued influx of funding and his team’s zealous enthusiasm for the work would be a combination difficult for a young hematologist to resist. “We want to attract the best and the brightest to this field to help us develop a drug that prevents thrombotic disease but doesn’t block the normal process of hemostasis—the minimization of blood loss after tissue injury,” he says, “That’s our holy grail.”