Fibrin Gel-Immobilized VEGF and bFGF Efficiently Stimulate Angiogenesis in the AV Loop Model
The modulation of angiogenic processes in matrices is of great interest in tissue engineering. We assessed the angiogenic effects of fibrin-immobilized VEGF and bFGF in an arteriovenous loop (AVL) model in 22 AVLs created between the femoral artery and vein in rats. The loops were placed in isolation chambers and were embedded in 500 µL fibrin gel (FG) (group A) or in 500 µL FG loaded with 0.1 ng/µL VEGF and 0.1 ng/µL bFGF (group B). After two and four weeks specimens were explanted and investigated using histological, morphometrical, and ultramorphological [scanning electron microscope (SEM) of vascular corrosion replicas] techniques. In both groups, the AVL induced formation of densely vascularized connective tissue with differentiated and functional vessels inside the fibrin matrix. VEGF and bFGF induced significantly higher absolute and relative vascular density and a faster resorption of the fibrin matrix. SEM analysis in both groups revealed characteristics of an immature vascular bed, with a higher vascular density in group B. VEGF and bFGF efficiently stimulated sprouting of blood vessels in the AVL model. The implantation of vascular carriers into given growth factor-loaded matrix volumes may eventually allow efficient generation of axially vascularized, tissue-engineered composites.
This study was supported by research grants from Xue-Hong and Hans Georg Geis, Baxter Healthcare Corporation, as well as the University of Erlangen (ELAN Program). The authors thank Professor Peter Greil and Mr. Peter Reinhard for production of the Teflon chambers. This work contains parts of Ms. Lucia Grabinger’s doctoral thesis. The authors thank Mr. Tobias Fey for preparation of the SEM specimens. The authors also thank Kristina Heidner and Simon Euler for their technical assistance.
- 25.Lametschwandtner A, Lametschwandtner U, Weiger T. (1984) Scanning electron microscopy of vascular corrosion casts—technique and applications. Scan. Electron Microsc. 663–95.Google Scholar
- 30.Polykandriotis E, Tjiawi J, Euler S, et al. (2007) The venous graft as an effector of early angiogenesis in a fibrin matrix. Microvasc. Res. 2007 Apr. 18 [Epub ahead of print].Google Scholar