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  Autologous growth factors to promote tissue in-growth in vascular deviceUSPTO Application #: 20060136050Title: Autologous growth factors to promote tissue in-growth in vascular device Abstract: Methods and devices for ameliorating stent graft migration and endoleak using treatment site-specific cell growth promoting compositions in combination with stent grafts are disclosed. Also disclosed is coating of autologous growth factor compositions onto stent grafts prior to stent graft implantation. Additional embodiments include stent grafts having autologous growth factor composition coatings useful for treating aneurysms. (end of abstract) Agent: Medtronic Vascular, Inc.IPLegal Department - Santa Rosa, CA, US Inventors: Jack Chu, Scott Doig, Brian Fernandes, Trevor Huang, Josiah Wilcox USPTO Applicaton #: 20060136050 - Class: 623001420 (USPTO) Related Patent Categories: Prosthesis (i.e., Artificial Body Members), Parts Thereof, Or Aids And Accessories Therefor, Arterial Prosthesis (i.e., Blood Vessel), Drug Delivery The Patent Description & Claims data below is from USPTO Patent Application 20060136050. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001] This application is a continuation-in-part of U.S. patent application Ser. No. 10/977,545, filed Oct. 28, 2004, which is herein incorporated by reference in its entirety. FIELD OF THE INVENTION [0002] Methods and devices for preventing vascular device migration using autologous growth factor composition-coated vascular devices are disclosed. Specifically, methods for producing autologous growth factor compositions and coating vascular devices with the compositions before device implantation are provided. BACKGROUND OF THE INVENTION [0003] A variety of implantable vascular devices, including stent grafts and stents, have been developed to treat abnormalities of the vascular system. Stent grafts are used to treat aneurysms of the vascular system and have also emerged as a new treatment for a related condition, acute blunt aortic injury, where trauma causes damage to an artery. Stents are used to treat areas of vessel narrowing or atherosclerosis. [0004] Aneurysms arise when a thinning, weakening section of vessel wall balloons out to more than 150% of its normal diameter. These thinned and weakened sections of vessel walls can burst, causing an estimated 32,000 deaths in the United States each year. Additionally, aneurysm deaths are suspected of being underreported because sudden unexplained deaths, about 450,000 in the United States alone, are often simply misdiagnosed as heart attacks or strokes while many of them may be due to aneurysms. [0005] U.S. surgeons treat approximately 50,000 abdominal aortic aneurysms each year, typically by replacing the abnormal section of vessel with a plastic or fabric graft in an open surgical procedure. A less-invasive procedure that has more recently been used is the placement of a stent graft at the aneurysm site. Stent grafts are tubular devices that span the aneurysm to provide support without replacing a section of the vessel. The stent graft, when placed within the artery at the aneurysm site, acts as a barrier between blood flow and the weakened wall of the artery, thereby decreasing pressure on the damaged portion of the artery. This less invasive approach to treating aneurysms decreases the morbidity seen with conventional aneurysm repair. Additionally, patients whose multiple medical comorbidities make them excessively high risk for conventional aneurysm repair are candidates for stent grafting. [0006] Stents are rigid, or semi-rigid, tubular scaffoldings that are used to treat vessel narrowing or atherosclerosis, the leading cause of death in the United States. Specifically, atherosclerosis and other forms of coronary artery narrowing are treated with percutaneous transluminal angioplasty ("angioplasty"). The objective of angioplasty is to enlarge the lumen of an affected vessel by radial hydraulic expansion. The procedure is accomplished by inflating a balloon within the narrowed lumen of the affected artery. After (or during) such an angioplasty procedure, stents are deployed at the treatment site within the vessel to reduce the risks of reclosure. Stents are generally positioned across the treatment site, and then expanded to keep the passageway clear. The stent provides a scaffold which overcomes the natural tendency of the vessel walls of some patients to renarrow, thus maintaining the openness of the vessel and resulting blood flow. [0007] While stent grafts and stents (hereinafter collectively referred to as "vascular devices") represent improvements over previously-used vessel treatment techniques, there are still risks associated with them. The most common of these risks is migration of the vascular device due to hemodynamic forces within the vessel. Stent graft migrations lead to endoleaks, a leaking of blood into the aneurysm sac between the outer surface of the graft and the inner lumen of the blood vessel. Stent migration can leave a treated area of a vessel more susceptible to reclosure. Such migrations of vascular devices are especially possible in curved portions of vessels where asymmetrical hemodynamic forces in the area can place uneven forces on the vascular device. Additionally, the asymmetrical hemodynamic forces can cause remodeling of an aneurysm sac which leads to increased risk of aneurysm rupture and increased endoleaks. [0008] Based on the foregoing, one goal of treating aneurysms and vessel narrowings is to provide vascular devices that do not migrate. To achieve this goal, vascular devices with stainless steel anchoring barbs that engage the vessel wall have been developed. Additionally, endostaples that fix vascular devices more readily to the vessel wall have been developed. While these physical anchoring devices have proven to be effective in some patients, improvements continue to be sought to assure the position of stent grafts once placed. [0009] Additionally, the combination of the metal scaffolding of most stent grafts and graft migration in a small percentage of cases has led to the contraindication of magnetic resonance imaging (MRI) in some patients having stent grafts. The magnetic fields used in this imaging process, when moving across the body, may cause insufficiently fixated metal-containing stents to migrate. [0010] One way to improve vascular device fixation is to administer to the treatment site, either before, during or relatively soon after implantation, a cell growth-promoting factor. This administration can be beneficial because, normally, the endothelial cells that make up the portion of the vessel to be treated are quiescent at the time of vascular device implantation and do not multiply. As a result, the vascular device rests against a quiescent endothelial cell layer. If cell growth-promoting compositions are administered immediately before, during or relatively soon after vascular device deployment, the normally quiescent endothelial cells lining the vessel wall, and in intimate contact with the vascular device, will be stimulated to proliferate. The same will occur with smooth muscle cells and fibroblasts found within the vessel wall. As these cells proliferate they can grow into, on and/or around the vascular device such that the vascular device becomes physically attached to the vessel lumen rather than merely resting against it. This endothelialization helps promote vascular device fixation. [0011] Endothelialization has been observed to naturally occur in some human stent grafts within weeks of implantation. This natural endothelialization is not complete or consistent, however, and therefore does not in some cases prevent the stent graft migration and endoleak. Methods to increase endothelialization are sought to improve clinical outcome after stent grafting. [0012] Based on the above discussed issues, additional methods for fixating stent grafts to vessel walls are needed to further prevent occurrences of endoleaks and stent graft migration. SUMMARY OF THE INVENTION [0013] The risk of stent graft migration can be reduced by delivering to the treatment site, as a coating on the stent graft, endothelialization factors such as autologous growth factor compositions. This administration can be beneficial because, normally, the endothelial cells that make up the portion of the vessel to be treated are quiescent at the time of stent graft implantation and do not multiply. As a result, the stent graft rests against a quiescent endothelial cell layer. If autologous growth factor compositions are administered to the treatment site with the stent graft deployment, the normally quiescent endothelial cells lining the vessel wall, and in intimate contact with the stent graft, will be stimulated to proliferate. The same will occur with smooth muscle cells and fibroblasts found within the vessel wall. As these cells proliferate they can grow into and around the stent graft lining such that the stent graft becomes physically attached to the vessel lumen rather than merely resting against it. This endothelialization helps to prevent stent graft migration. These methods can promote healing, reduce endoleaks and minimize device migration by promoting endothelial tissue in-growth. [0014] Based on the foregoing, embodiments according to the present invention provide stent grafts having autologous growth factor compositions coated thereon for the treatment of aneurysms, and associated methods for using and/or manufacturing the stent grafts. Additionally, stent grafts are disclosed which provide structural support for weakened arterial walls while the accompanying compositions promote tissue in-growth to reduce the chance of graft migration and endoleaks. [0015] Therefore, embodiments according to the present invention provide methods for providing a stent graft and a cell growth-promoting composition comprising obtaining autologous platelet rich plasma (PRP) from a patient in need of a stent graft, activating the PRP to form autologous growth factor composition, coating the stent graft with the autologous growth factor composition and implanting the autologous growth factor composition-coated stent graft into a vessel at a treatment site in a patient wherein the autologous growth factor composition-coated stent graft induces endothelialization of the stent graft. [0016] In one embodiment of the method for providing a stent graft and a cell growth-promoting composition, the coating step comprises injecting autologous growth factor composition through at least one injection port in a delivery catheter such that said autologous growth factor composition wets the stent graft disposed within the delivery catheter. [0017] In another embodiment of the method for providing a stent graft and a cell growth-promoting composition, the method further comprises providing a drug in combination with the autologous growth factor composition wherein the drug is selected from the group consisting of small molecules, peptides, proteins, hormones, DNA or RNA fragments, cells, genetically engineered cells, genes, cell growth promoting compositions, matrix metalloproteinase inhibitors, antibiotics, cyclooxygenase-2 inhibitors, angiotensin-converting enzyme inhibitors, glucocorticoids, beta blockers, nitric acid synthase inhibitors, antioxidants and cellular adhesion molecules. [0018] In yet another embodiment of the method for providing a stent graft and a cell growth-promoting composition, the activating step comprises mixing said PRP with an activating agent such as, but not limited to, a platelet agonist. In one embodiment the platelet agonist is adenosine diphosphate (ADP), preferably at a concentration of 5 to 20 .mu.M, or thrombin receptor activating peptide (TRAP), preferably at a concentration of 5 to 10 .mu.M. [0019] In an embodiment of the method for providing a stent graft and a cell growth-promoting composition, the autologous growth factor composition is centrifuged to remove cells and cellular particulates prior to the coating step. [0020] In another embodiment of the method for providing a stent graft and a cell growth-promoting composition, the said treatment site is an aneurysm site Continue reading... 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