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7036077 
Journal Article 
Endothelial cell proliferation and progenitor maturation by fibrin-bound VEGF variants with differential susceptibilities to local cellular activity 
Ehrbar, M; Metters, A; Zammaretti, P; Hubbell, JA; Zisch, AH; , 
2005 
ELSEVIER 
AMSTERDAM 
93-109 
15588897 
WOS:000226086800010 
A number of vascular therapies could benefit from advanced methods for presentation of angiogenic growth factors, including growth of endothelium oil small caliber vascular grafts and revascularization of ischemic tissue through induction of collateral vessels and microvessels. To explore methods to optimize the presentation and release of angiogenic factors ill such applications in device integration and tissue repair, we studied three variant forms of vascular endothelial growth factor 121 (VEGF(121)), each with differential susceptibility to local cellular proteolytic activity, formulated within fibrin matrices. (1) The prototypic variant alpha 2PI1-8-VEGF(121) remains immobilized in fibrin matrices until its liberation by cell-associated enzymes, such as plasmin, that degrade the fibrin network [slow, cell-demanded release; J. Control. Release 72 (2001) 101-113]; the alpha 2PI1-8 domain serves as a site for covalent attachment to fibrin during coagulation. (2) We created a new VEGF variant, alpha 2PI1-8-Pla-VEGF(121) that couples to fibrin via a plasmin-sensitive sequence (Pla). Cleavage of this target site by plasmin enables direct release Of alpha 2PT1-8-Pla-VEGF(121) from bulk matrix degradation (accelerated, cell-demanded release). (3) Native VEGF(121) (burst, passive release) was considered as a reference. VEGF release profiles were determined experimentally as well as mathematically, alpha 2PI1-8-Pla-VEGF(121) being released ca. fourfold more quickly than alpha 2PI1-8-VEGF(121), both being retained compared to native VEGF(121); the differences in release could be accounted for based on knowledge of the plasmin sensitivity of the bound growth factor and the structure of the fibrin network. The bound factors were competent in inducing endothelial cell proliferation, the matrix-bound forms being more effective than native VEGF(121); as well as competent in inducing endothelial progenitor cell maturation into endothelial cells. These matrix-bound variants of VEGF(121) may be particularly useful where retention in locally applied surgical sites is desired, such as prevention of washout from vascular graft coatings and slowing loss from tissue ingrowth matrices used in local tissue revascularization and repair. (c) 2004 Elsevier B.V. All rights reserved. 
8th European Symposium on Controlled Drug Delivery 
Noordwijk, NETHERLANDS