Abstract
Vascular surgery is undergoing a sea of change, with recent advances in technology enabling surgeons to do more than ever for our patients. Also very exciting is the continued steady rate of advances and discoveries reported by basic science research laboratories, especially those studying vascular biology. This issue of Vascular provides a small glimpse into this new world of scientific exploration. Each of the articles in this issue is written from the laboratory of a vascular surgeon-scientist and relates new concepts in basic science that may emerge into the commonplace technology of the future, perhaps incorporated into everyday use for practicing surgeons.
Vascular surgeons are well aware of the significance of lower extremity chronic critical ischemia to the lives and functionality of our patients. Although conventional open surgical techniques as well as recent endovascular approaches have allowed surgeons to revascularize the major arteries of the leg, our inability to deal with the disease of smaller vessels still relegates many patients to amputation. Thus, it is natural to be excited about the prospect of therapeutic angiogenesis, the formation of additional collateral blood vessels that will supply the ischemic leg in spite of the surgeon's inability to do so. However, such trials are clearly in their infancy, with current debate even on simple points, such as which agents to use and the regimen to deliver the agent, including dose, frequency, method, and site of delivery. In this context, Dr. Ho and colleagues review the biology of hypoxia-inducible factor (HIF)-1, a master regulator of cellular response to ischemia. Understanding the biology of HIF-1 will likely lead to increased understanding of how to regulate therapeutic angiogenesis, allowing this technology to be part of the surgeon's armamentarium in the struggle against ischemia.
Understanding how to regulate angiogenesis, the formation of collateral vessels from preexisting vessels, allows natural comparison with vasculogenesis, the formation of entirely new blood vessels from circulating precursor cells. Gallagher and colleagues review new data regarding the function of endothelial progenitor cells (EPCs), newly described stem cells that normally reside in our patients' bone marrow but that can be stimulated to enter the circulation and home to ischemic areas. The ability to understand vasculogenesis is critical to the ability to regulate it for patients in whom the ability to heal wounds is abnormal, such as patients with advanced diabetes. Most vascular surgeons have extensive experience with these patients, and advances in EPC biology may lead to novel therapies that future surgeons can deliver.
Although stem cells are exciting and may seem like a technology relegated to the distant future, DiMuzio and colleagues show us how these cells may provide us with improved capacity for patients to tolerate bypass grafts. Although this review is couched in the language of tissue engineering, the new field that combines cells and organizational matrix into “neotissue,” it will be clear to most vascular surgeons that our everyday performance of surgical bypass, and placement of endoluminal stents, is simply the process of tissue engineering in patients. Given that use of stem cells in vascular devices may allow improved healing, incorporation of stem cells into new technology is a natural progression started from the founding fathers of our specialty and should be a comfortable step for most surgeons.
Blood vessel pathology is traditionally divided into diseases that narrow the lumen, leading to stenosis and distal ischemia, and diseases that expand the lumen, leading to aneurysmal expansion and rupture. The second group of articles in this issue is thus centered on aneurysmal disease. Chaer and colleagues review several models of aneurysmal disease that are currently being used in vascular surgery laboratories. Some of these models are based in smaller animals, such as mice, which allow understanding of the pathophysiology of aneurysmal disease on a molecular basis and will undoubtedly lead to new treatments and perhaps even prevention of aneurysms. Other models, in larger animals, are critical to test new devices and implants and lead to improved understanding of our patients' post-treatment biology, such as the significance of endoleak and endotension.
Endovascular aneurysm repair has been a primal force in the endovascular revolution. Vascular surgeons remain advocates of the access vessels and continue to recognize the need for creative access to allow endovascular work and to repair vessels damaged by our own interventions. Lin and colleagues demonstrate the molecular consequences of adverse sheath–vessel interaction, suggesting new ways to test future devices and perhaps minimize the adverse impact on access vessels. Although this work may suggest paths to develop lower-profile devices, as well as new metals that capitalize on vessel–device interaction, it is clear that better understanding of our interventions is critical.
Many vascular surgeons enjoy teaching our medical students and fellows how blood vessel pathology, both atherosclerotic and often aneurysmal disease, is inflammatory, with tumor-like invasion of surrounding structures. Thus, Albadawi and colleagues review the critical role of poly(ADP-ribose) polymerase (PARP) in vascular inflammation. Understanding PARP biology may lead to novel agents that will prevent spinal cord ischemia after open or endovascular treatment of thoracic and thoracoabdominal aneurysms and may ultimately provide insights into atherosclerotic disease as well.
Recent advances in patient care are critically dependent on technology, spurring patient care in both preoperative diagnosis and operative treatment. Fitzgerald and colleagues review recent advances in magnetic resonance (MR) imaging. Although most surgeons are quite familiar with the importance of MR angiography to the care of vascular patients, analysis of the quantitative MR data is an area of expanding application. It is likely that the quantitative analysis of carotid plaque morphology will lead to improved risk stratification for patients for whom a diagnosis, or a treatment plan, is unclear.
Each of these articles, although not an exhaustive list, provides a different perspective of what future technology holds. I would like to thank the sponsors of this issue for their endorsement of the future of vascular surgery. In addition, I would like to thank Dr. Veith, editor-in-chief of this journal, for the courage to dedicate this issue to the future of our specialty. Lastly, I would encourage your continued support of the American Vascular Association, which continues to support the ownership of vascular disease by vascular surgeons in its continued support of basic science research in the laboratories of vascular surgeons. I hope that you enjoy this issue and keep it on your shelf for future reference.