Modifizierung von Kollagenmatrizes zur Verbesserung der Angiogenese : Eigenschaften von heparinisierten und mit VEGF beladenen Kollagenschwämmen
As a therapy for large skindefects (e.g. diabetic ulceras) artificial skin substitutes are promising alternatives. Unfortunately most of the common products have a very low angiogenetic potential and therefor can be used only temporarely. The immobilisation of growth factors could prevent the strong in vivo-degradation of growth factors and could enhance angiogenesis. In this study the in vitro-release of VEGF of modified and non modified (Control group) collagen sponges and their biological effects in the endthelial cell culture will be determined. Due to the use of EDC (ethylen carbodiimid) a crosslinking of heparin to collagen and a crosslinking of the collagen sponge itself can be achieved. By varying the amount of EDC and heparin the following groups of sponges ( size of 5*5*5 mm) are formed: 0mg EDC and 0 mg heparin per mg collagen (Control); 1mg EDC and 0mg heparin; 1 mg EDC and 1 mg heparin; 2mg EDC and 1 mg heparin. The sponges are loaded with the growth factor VEGF (vascular endothelial growth factor) (10 ng/sponge) and the in vitro release of VEGF for 48 hours (with/ without collagenase) is quantified by Enzym-Linked Immuno Sorbent Assays (ELISAs). Furthermore under the influence of the modified collagen sponges the proliferation of endothelial cells (HUVECs) is investigated. The increase of proliferation is determined by the BrdU-test and the total amount of cells by counting the cells in the Neubaukammer after 1, 3 and 5 days. In comparison to the native sponges the in vitro-release of the modified, especially with heparin modified sponges, show a slower release of VEGF at different temperatures (roomtemperature and 37°C) as well as at experiments with an in vitro degradation of the collagen sponges caused by collagenase. Even in the cell culture the heparinized sponges show the strongest stimulus of proliferation and the highest total amount of cells. The results show that binding VEGF to heparin modified collagen sponges induces an increase of the endothelial cell proliferation. Apart from VEGF, the crosslinking of the collagen sponges itself has an angiogenetic potential.
info:eu-repo/classification/ddc/610, Medizin, Angiogenese, Kollagen, Vascular endothelial Growth Factor, angiogenesis, collagen, VEGF
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