During his PhD studies, Karl Schneider is working with human placenta material. Using the decellularized matrix of the human placenta has great potential for new approaches in tissue engineering. One obvious advantage is that the placenta can be readily harvested without harm to the donor. It is on one hand a rich source of human cells and also of human ECM components as well as vascular structures. He is following a new dual-level strategy to create prevascularized tissues, in vitro. The decellularized vascular structure is used for recellularization with human endothelial cells, isolated from the human umbilical cord vein (HUVECs). To create perfect conditions new perfusion and bioreactor systems are developed and used for the decellularization and recellularization of biological tissue matrix.