ABSTRACT
Effective vascularization is a prerequisite for the success of various different tissue engineering concepts. While simultaneous administration of basic fibroblast growth factor (FGF-2) and vascular endothelial growth factor (VEGF) has been previously demonstrated to boost angiogenesis, the combined long-term delivery of both growth factors from biomaterials is still a major challenge. In this work, two important heparin binding cytokines were delivered in parallel from a modular starPEG (multi-armed polyethylene glycol)--heparin hydrogel system to human umbilical vein endothelial cells (HUVECs) grown in culture and in a chicken embryo chorioallantoic membrane (CAM) model. As the utilized gels contain high quantities of heparin, loading and subsequent release of both growth factors (as determined by radiolabeling studies and Enzyme-Linked Immunosorbent Assay [ELISA]) occurred independently from each other. The combined delivery of FGF-2 and VEGF through starPEG-heparin hydrogels resulted in pro-angiogenic effects in vitro (study of cell survival/proliferation, morphology and migration) and in vivo (quantification of CAM vascularization) being clearly superior over those of the administration of single factors. Consequently, the independent delivery of growth factor combinations by biohybrid starPEG-heparin matrices allows for the precise multifactorial control of cellular processes critically determining regeneration.
Subject(s)
Drug Carriers/chemistry , Fibroblast Growth Factor 2/administration & dosage , Heparin/chemistry , Neovascularization, Physiologic/drug effects , Polyethylene Glycols/chemistry , Vascular Endothelial Growth Factor A/administration & dosage , Animals , Cell Adhesion/drug effects , Cell Culture Techniques , Cell Proliferation/drug effects , Cell Survival/drug effects , Chick Embryo , Chorioallantoic Membrane/blood supply , Chromatography, High Pressure Liquid , Drug Combinations , Enzyme-Linked Immunosorbent Assay , Fibroblast Growth Factor 2/pharmacology , Human Umbilical Vein Endothelial Cells , Humans , Hydrogels , Oligopeptides/chemistry , Vascular Endothelial Growth Factor A/pharmacologyABSTRACT
Strategies to control the delivery of growth factors are critically important in the design of advanced biomaterials. In this study we investigated the binding and release of fibroblast growth factor 2 (FGF-2) to/from a biohybrid hydrogel matrix by four independent analytical methods: radioisotope and fluorescence labeling, amino acid analysis and Enzyme-Linked Immunosorbent Assays (ELISA). The compared analyses provided qualitatively similar uptake characteristics while the results of the FGF-2 quantification strongly depended on the particular experimental conditions. The release kinetics of FGF-2 from the gels could be monitored sensitively by (125)I labeling and by ELISA-techniques. The latter method was concluded to be advantageous since it permits the application of unmodified ("native") growth factors.
