Preliminary in vivo evaluation of tissue engineered venous grafts fabricated based on endothelial progenitor cells

Abstract

To explore the feasibility of the tissue engineered venous grafts (TEVGs) constructed in vitro based on canine autologous bone marrow-derived endothelial progenitor cells (EPCs) and porcine decellularized aortic scaffolds implanted into the canine inferior vena cava. To draw out a volume of 8 - 12 ml of bone marrow from the canine (n = 8), to culture and expand EPCs in vitro using conditioned medium. After labeled with a red fluorescent dye PKH26-GL, the cells were seeded onto the luminal surface of decellularized porcine scaffolds with single, rotative method for 4 h. Following static culture for 24 - 72 h, the hybrids were implanted to replace autologous canine inferior vena cava about 4 cm long. Meantime one femoral artery-venous shunt about 1 cm long was performed. The non-seeded decellularized scaffolds (n = 4) were performed the same as control. Angiography was performed and the hybrids were explanted for morphology and labeled cells' immuno-fluorescence examinations at postoperative 10 d, 4 weeks and 12 weeks, respectively. The patent number of experiment (control) group were 7/7 (2/4), 6/6 (2/2) and 4/4 (1/2) at postoperative 10 d, 4 weeks and 12 weeks, respectively. At 12 weeks, tightly confluence endothelial cells which covered the whole inner luminal surface of the explants were detected by immunohistochemistry of factor VIII and scanning electron microscopy, while fibrin-based pseudo-intima was detected on the inner luminal surface of matrix in the solo patent dog from the control group. Meanwhile, fibroblasts and alpha-actin positive cells in the matrices were found by transmission electron microscopy and alpha-actin immunohistochemistry. PKH26-GL labeled EPCs sustained on the luminal surface at a rather proportion accompanied by newly formed endothelial cells. However, the explants in both groups showed partial stenosis. Such constructed tissue engineered venous graft based on canine autologous bone marrow-derived endothelial progenitor cells and porcine decellularized aortic matrices is promising and deserve to further improvement and testing.