Background
Saving Suicidal Hearts
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Jagat Narula of the University of California at Irvine, where he is Professor of Medicine, Head of Cardiology and Associate Dean, was the Hein Wellens Visiting Professor at the University of Maastricht' s School of Medicine for the academic year 2004-05. Hein Wellens, the 'Grand Old Man' of the discipline in the Netherlands, became chairman of the Department of Cardiology at Maastricht University in 1977 and a member of the Netherlands Royal Academy of Sciences in 1990. One of the fathers of clinical Electrophysiology, he made seminal contributions to an understanding of arrhythmias in his own work and in the work of his colleagues and students in a Cardiology and Arrhythmology in a career lasting 33 Years. |
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Jagat Narula completed his medical training in India, including a fellowship in cardiology at the All India Institute of Medical Sciences in New Delhi, where he also received a Ph.D. in cardiovascular immunology. He subsequently trained in cardiology and in heart failure/ transplantation at Massachusetts General Hospital and Harvard Medical School and later joined the faculty at Harvard. Most recently, he held the endowed chair of cardiology, as Professor of Medicine, and Director of the Heart Failure/Transplantation Center at Philadelphia's Hahnemann University Hospital. A major development in Professor Narula's work came with a breakthrough in unveiling the secrets of end-stage heart failure, a malady that had puzzled scientists for years. Narula and his colleague discovered that when heart failure sets in, heart muscle cells become so distressed that they program themselves to die. However, in subsequent revelations, he demonstrated that, although the cascade of cell death is initiated, it does not conclude and leaves the cells in suspended animation. "While that contributes to inability of the heart to pump, the shells of the cells remain viable," he says.
Professor Narula insists that heart failure is reversible and raises hope for millions of sufferers across the world. Before this interview in Maastricht recently, Jagat Narula was talking toan enthusiastic group of students and colleagues about the clinical feasibility of noninvasive detection of apoptosis (cell death) in heart failure as well as vulnerable atherosclerotic lesions. This work has resulted from the collaborative efforts between his laboratory and the one in Maastricht. Professor Narula, the man, is a youth ful 47 and an unusual man in many ways. His daily schedule would be a daunting experience to any lesser being, for he gets up at three o'clock every morning when his working day starts, which usually runs to about 7 in the evening. Then it is time to go home again for some quality time with the family - his wife who is a pathologist and his two teenage children, a boy and a girl - and dinner until about 9. He works again, usually on his editorial responsibilities, until 10.30 or 11.00 when he goes to bed again for another brief night's sleep. It is accordingly not altogether surprising that his resumé extends to cover more than 80 pages. To use a modern analogy, drawn from IT, Jagat Narula is an Open Source man believing in synergy and international cooperation. Modern cardiology is a good reflection of this, with scholars crossing continents and clinicians and the lab people joining hands. The exchange fellows are on the same team and the Wellens Chair is extremely valuable in providing funding. Leo Hofstra and Chris Reutlingsperger, from Maastricht, have been over several times to his laboratories in the US. Three fellows have rotated through the lab and three PhD students from this side have worked with Professor Narula; one PhD student is expected to arrive in Maastricht. The program has led to 20 manuscripts and book chapters, numerous long-term collaborative projects with a strong focus on molecular imaging. Dean Narula has visited Maastricht three times for the Wellens visiting professorial assignment and has contributed extensively to develop common research endeavors and has taught students and cardiology fellows in Maastricht. This openness and the interaction allows scholars to identify individual strengths, is all to the good of the scientific community. Dr. Narula will visit again in August, as the concluding trip in his tenure of the Wellens Chair. This, Hofstra maintains, will be a celebration of a glorious year and fitting tribute and honor to the legacy of Hein Wellens. It is not just California, Maastricht, Boston and Philadelphia that are part of the circuit; Barcelona is in, as is Pavia and Ospedale Bufalini near Bologna in Italy and Oxford too. Irvine's cardiology lab instills focus and induces global atmosphere of collaboration and camaraderie. Jagat Narula is an ambassador for the translational research and constantly strives to close the gap between the clinic and the lab bench. His golden message to the budding cardiologists, "Clinical medicine and basic research are not mutually exclusive. Basic Science makes you a better clinician." And that is music to the ears of the Old Master, Hein Wellens. When all is said and done, Professor Narula has no time to waste. He might play a bit of badminton or tennis with his son, but his focus is on the preventive medicine at the molecular level. His battle is directed at the identification of patients that are likely to develop heart failure as also those who harbor the atherosclerotic lesions that are likely to result in heart attacks or sudden death.
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European Vascular Genomics Network
On the 10th of May 2004, the operational launch of the European Vascular Genomics Network (EVGN), the first ever European Union funded Network of Excellence in the field of cardiovascular disease, was announced in Paris. EVGN promotes multidisciplinary interaction by uniting 25 basic and clinical institutions (encompassing 35 academic groups), 2 biotechnology companies and 1 management company, from 10 EU Member or Associated States.
CARIM is participating in 8 "work packages" under supervision of the professors Harry Struijker Boudier, Mat Daemen, Marten Hofker, Cathrien Bruggeman and Jo De Mey. Within these "work packages" 46 researchers, Phd-students and technicians from CARIM are involved.
This Network is one of the Networks of Excellence funded by the European Union within its 6th Framework Programme "Life Science, genomics and biotechnology for Health", aiming at integrating and strengthening the European research area. The EVGN benefits from a global budget of 59.317.827 Euros including 9 million Euros granted by the European Union over a 5 year-period. The EVGN focuses on the study of cardiovascular disease. It integrates new post-genomic approaches (i.e. advanced techniques based on the simultaneous investigation of thousands and thousands of genes and proteins) into more conventional biomedical and biotechnological approaches.
EVGN was implemented on January 1st, 2004, to act as an interface between basic and clinical scientists in order to promote and accelerate the transition of knowledge in vascular biology to improve diagnosis and treatment of cardiovascular diseases.
EVGN is headed by an Executive Committee consisting in 15 European leading scientists in vascular biology, and coordinated by Dr. Alain Tedgui, Inserm, Paris, France. This is a unique effort with the main goal bundling the scientific potential of European research in Vascular Biology. This will be accomplished by persuing a joint research programme and building a communication platform, facilitating data exchange, sharing research tools, and introducing training and scientific exchange programs.
The research activities of the EVGN concentrate on three major areas of cardiovascular disease and therapy:
1. endothelial dysfunction that plays a crucial role in the development of atherosclerosis (the endothelium is the inner lining of blood vessels);
2. instability of the atherosclerotic plaque that is the main cause of arterial thrombus (blood clot) formation leading to coronary artery occlusion and heart attack (the atherosclerotic plaque is an accumulation of scar tissue, blood cells, cholesterol, and other fatty substances into the artery wall; the build-up of plaque narrows the arteries and slows the flow of blood);
3. therapeutic angiogenesis that opens avenues for novel treatment of heart disease meant to improve cardiac oxygenation and reduce heart failure (angiogenesis - from the Greek words angêion, which means "vase", and génesis, which means "birth" - is the science that studies the formation of new vessels which would improve cardiac blood perfusion).
Each of the three areas has the potential for the development of new diagnostic and therapeutic strategies that will provide permanent benefits for patients. This project integrates post-genomic research into the more established biomedical and biotechnological approaches to cardiovascular disease.
The work plan of the EVGN schedules several workshops on different EVGN research area or tools called "work packages". The first workshop on "Genomics and proteomics of the unstable plaque" was organized on May 14th in Amsterdam, The Netherlands. The purpose is to make an inventory of the requirements for bioinformatics and to examine how to integrate different platforms on bioinformatics.
The first EVGN Summer School for 60 PhD students of all the participating institutes has been organized by CARIM in Maastricht, The Netherlands In July 2005.
topMolecular Imaging in Ischemic heart disease
2004 marked the start of the research program "Molecular Imaging in ischemic heart disease". This program was initiated by CARIM and is carried out in a consortium, consisting of CARIM, the faculty of Biomedical Engineering of TU/ e, Philips Research and Organon; it is subsidized by the Dutch government in the framework of BSIK. The aim of the consortium is to establish a knowledge platform for molecular imaging in ischemic heart disease. It harbors expertise in all areas that are required for the development of the technologies (see figure). The two core technologies that will be developed in the project are chemical, i.e. the skill of designing functional probes, and instrumental, i.e. the imaging of the in vivo distribution of the probe. Both the chemical research and the instrumental research will concentrate on the study of probes for MRI and Ultrasound, because of the expected leading role of these two modalities in future clinical molecular imaging. | ||
| Building blocks for moluecular imaging |  | In the probes for MRI and Ultrasound, polymer based scaffolds are often present as carrier for both the targeting ligand and the imaging label. Selected polymers with potential application in the development of MRIprobes (e.g. dendrimers) will be studied in depth to increase understanding of the efficacy of the MRI imaging label. |
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Three of these processes, "atherosclerosis", "angiogenesis" and "infarct healing" will be topic of focus in our project. Not only do they represent important aspects of ischemic disease, but molecular imaging targets and significant progress in ligand finding for these is already available. For each topic an expertise group has been brought together | ||
CARIM molecule of the year: Annexin A5
 | Nowadays the name "annexin five" is for most of us synonymous to the detection of apoptosis, a process of cell suicide that counterbalances cell proliferation of multicellular organisms. Few people know its discovery and its semantics. This condensed overview highlights aspects of the evolution of annexin A5 that were critical for its current status. If one looks back to annexin A5's history one sees a bumpy and curved road that was unpredictable in its course while one were on it and tried to peek into the future. Its trajectory, however, conformed to the method called science, which is observation, reasoning and experimentation. |
| Impression of the folding of the primary structure of the annexin A5- molecule. This impression is based on its resolved tertiary structure. | |
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In the mean time other laboratories discovered identical proteins and dubbed those while being inspired by the scientific framework in which the discovery was made. This led to an exotic collection of names for a single protein. VAC was also named PP4, placental anticoagulant protein I, anchorin CII, endonexin II, calphobindin I and lipocortin V. During our search for the VACcDNA we picked up a clone of a similar but not identical protein. We termed this protein VACß and renamed VAC with VACa. Elucidation of VACa and ß's primary structures revealed that they both belong to a multigene family of proteins that share a set of structural and functional features. Proteins of this family were called annexins and accordingly VACa and VACß received the consensus names annexin V and annexin VIII, respectively. Later these names were changed into annexin A5 and annexin A8 for the human proteins due to the explosive expansion of the family by the awareness of its presence in other phyla. The studies on the antithrombotic activity regrettably did not enjoy the support required for successful development of annexin A5 (anxA5). In the late 80ties and beginning 90ties of the last century the paradigm of a specific interaction was a protein-protein interaction. AnxA5's interaction with the phospholipid PS was regarded as being far from specific, at least within the scientific community of Thrombosis and Haemostasis. The road of its research would have been certainly terminated in our laboratory if a publication of Valerie Fadok would not have come for its rescue. In 1992 she published a paper in the Journal of Immunology, which reported on the cell surface exposure of PS during apoptosis of lymphocytes. The cell surface exposed PS appeared to function as an "eat me" signal towards macrophages, which, in response, engulf the apoptotic cell through phagocytosis. Reading this paper I figured that if a macrophage could "see" the cell surface exposed PS of the apoptotic cell then anxA5 would be able do the same. This created a new and unforeseen curve in the road of anxA5 research bending it to a "bright" future. Multiple collaborations within and outside of the University Maastricht explored anxA5 in this novel setting. The collaborations with Bert Schutte (University Maastricht), Christl Vermeij- Keers and Stefan van den Eijnde (Erasmus University Rotterdam), Rien van Oers (AMC, Amsterdam), Dirk Roos (CLB, Amsterdam), Istvan Vermes and Clemens Haanen (Medisch Spectrum Twente) and Douglas Green and Seamus Martin (La Jolla Institute for allergy and immunology, San Diego) merged into a firm establishment of anxA5 as a universal imaging probe for the detection of apoptosis in vitro, and in vivo in a mouse embryo model. Most of these studies were performed with optical imaging using fluorescently labeled anxA5. As became apparent later during its development anxA5 was a Molecular Imaging probe "avant la lettre". The phenomenon of PS exposure during apoptosis appeared to be ubiquitous regardless of the cell type and cell death inducing trigger. The interaction of anxA5 with PS indeed appeared to have a flavor of being unspecific but only in the sense that the affinity of their interaction is not determined by the phylogenetic origin of the cell in apoptosis. AnxA5's interaction with PS is not restricted to mammalian apoptotic cells expressing PS. AnxA5 recognizes also apoptotic cells from worms, flies and plants. As such anxA5 rapidly gained name and fame in a broad part of the scientific community of the Life Sciences. I vividly recall a discussion about anxA5 as an imaging probe with a famous pathologist of the University Hospital of Maastricht. He proclaimed "Ah, niks zien", which is a phonetic similarity of annexin in the Dutch tongue and meaning "Ah, nothing to see". What's in a name? The interpretation of the pathologist appeared to be correct for the healthy tissues but incorrect for pathological tissues as turned out afterward. Apoptotic cells are efficiently cleared in healthy tissues by phagocytosis. The balance of apoptosis and phagocytosis is disturbed in pathological tissues giving rise to a sustained presence of apoptotic cells in these tissues. Hence, pathological tissues should show more uptake of anxA5 and, consequently, the uptake of anxA5 by a tissue could tell us something about the pathological state of the tissue. This notion propelled the popularity of anxA5. The next significant step forward for anxA5 was made in collaboration with Leo Hofstra. He developed a Molecular Imaging setup to visualize apoptosis in a mouse model of ischemia/reperfusion injury of the heart. It was demonstrated that anxA5 uptake by the heart was a function of the time of ischemia and reperfusion. Together we translated with the help of Guido Heidendal the anxA5 imaging protocol from preclinical application into clinical evaluation. The first patients, who were evaluated, were patients with acute myocardial infarction undergoing reperfusion therapy. These patients were injected intravenously with Technetium-labeled anxA5 and imaged with a gammacamera. SPECT analysis clearly revealed the infarcted area of the heart as a hot-spot of accumulated Technetiumlabeled anxA5. This study was the first to demonstrate the feasibility of the anxA5 imaging protocol in the clinical arena. Currently, the Technetium-anxA5 imaging protocol has been applied to image cell death in cardiovascular and oncologic patients. In close collaboration with Jagat Narula (University of California Irvine) it was demonstrated that the anxA5-imaging protocol shows the promise to discriminate between stable and unstable plaques in patients with lesions in the carotid arteries. This promise was substantiated by the findings that the biology of the unstable plaque is characterized by the presence of apoptotic cells. Looking back it is clear that the bumpy and curved road has traversed anxA5 right into the spotlight of Molecular Imaging, a new and popular link of the chain of personalized medicine. AnxA5 is to date one of the few examples of a successful Molecular Imaging agent. That is the reason why it is a welcomed guest for academia and companies such as Philips, GE and Siemens that are involved in the intriguing and promising concept of personalized medicine. Will the road end here? Probably not because anxA5 is moving on. While still being attractive in the Molecular Imaging arena it has entered already the new arena of the nanotechnological approach of therapeutics. Recently we discovered that anxA5 opens a novel portal of cell entry in a nanomechanical manner that is driven by its ability to form a 2-dimensional crystal on the surface with expressed PS. We showed that anxA5 bears a key of nanotechnological nature to open cellular doors and to carry attached compounds into the cell having surface expressed PS. This phenomenon has gained particular interest in the light of our findings that tumor cells and stressed cardiomyocytes express transiently PS at their surface without committing apoptosis. Without being foreseen, a novel curve of its road was thus created. We now regard this novel property as the "Seek, Enter and Act" paradigm. AnxA5 targets an attached drug to the PS expressing cell and delivers the drug into the cell where it can act. The acting should be cell killing in the case of tumor cells and cell rescue in the case of stressed cardiomyocytes. Where the road will lead us to remains to be seen. However, if applying the rules of the method called science the road will very likely provide unexpected and exciting points for dazzling sightseeing, no matter what the name of anxA5 then will be. | |