Untersuchung zur Expression von VEGF und HIF-1α im Zusammenhang mit der Einheilung unterschiedlicher nanofaserbasierter Knochenersatzstoffe

This dissertation examines the correlation of the angiogenesis during the incorporation of PLLA-nanofibre scaffolds in the healing process of bone defects of living rats and the expression of the signalling molecule HIF-1a as well as the growth factor VEGF with immunohistochemical methods. In the research we verified HIF-1a and VEGF-positive cells in calvarial defects of rats with immunohistochemical methods. The analysis of HIF-1a showed us that none or only a few positive cells could be proven. Hypoxia was never indicated at any time. The VEGF-analysis supported this result. This analysis showed only an expression on basic. We could not verify a correlation between the healing of the bone defect and an alteration of HIF-1α or VEGF. The results always showed a basal expression both in HIF-1a and VEGF regardless of the bone healing, the used material or the time of the examination. The proven basal expression was absolutely sufficient for the successful ossification in the PLLA/BMP-2-group. On the basis of these results we assume that there was always provided enough oxygen for the cells migrating to the scaffolds. We could not observe hypoxia at any time. Without hypoxia there will neither be an increasing expression of VEGF nor an amplified angiogenesis. Therefore the angiogenesis does not affect the deficient incorporation of the nanofibre scaffolds in the ossification process and the lack of VEGF is not the reason for failure of bone healing. As a conclusion of our results follows to sum up that in such a case the adding of VEGF into the scaffolds would not constitute a benefit for the ossification process.