Abstract:

BACKGROUND: Studies of tissue-engineered small caliber vessels are mainly focused on the construction in vitro. The long-term results of tissue-engineered small caliber vessels in vivo are rarely reported so far.
OBJECTIVE: To observe the histological changes of a tissue-engineered small caliber vessel prepared with acellular porcine femoral artery scaffold and sheep bone marrow mesenchymal stem cells implanted into a sheep for 12 months.
METHODS: Twelve sheep were randomly divided into scaffold group and recellularized scaffold group. In the scaffold group, the decellularized extracellular matrices, that femoral arteries of pigs were decellularized, were implanted in the right femoral artery of the sheep. In the recellularized scaffold group, the left femoral artery of the sheep were implanted with the recellularized extracellular matrices that were established by implantation of bone marrow mesenchymal stem cells on the decellularizated extracellular matrices and preconditioning in vitro. The autologous contralateral femoral artery in the two groups served as control group. Histomorphology and calcium content in the grafts were evaluated through scanning electron microscopy, pathological methods, and O-cresolphthalein complex method at the postoperative 12 months.
RESULTS AND CONCLUSION: All the grafts kept patency after 12 months. There were no expansion, thrombosis, and thickening of the cavity and wall, but rigidity and weakened pulsating in all the grafts. The intima of all the grafts was covered with vascular endothelial cells at 12 months after operation. Compared with the control group, calcium content is significantly higher in the scaffold group (P < 0.01) and the smooth muscle cells density lower significantly in the scaffold and the recellularized scaffold groups (P < 0.01). Compared with the scaffold group, there were lower calcium content (P < 0.05) and higher smooth muscle cells density (P < 0.01) in the recellularizated scaffold group. These findings indicate that it is essential to improve the long-term results of tissue-engineered small caliber vessels by increasing the smooth muscle cells density.