Intima/medulla reconstruction and vascular contraction-relaxation recovery for acellular small diameter vessels prepared by hyperosmotic electrolyte solution treatment

This study aims at the evaluation of blood vessel reconstruction process of decellularized small diameter vessels prepared by a hyperosmotic electrolyte solution treatment not only histologically but also physiologically in rat transplantation model. Complete cell removal by a hyperosmotic electrolyte solution treatment was confirmed by hematoxylin/eosin staining and scanning electron microscopic observation. All acellular vessels transplanted into the rat abdominal aorta were patent up to 14 months. One week post-transplantation, the vWF-positive cells were observed on the luminal surface but the layer formation did not complete. Five weeks following transplantation, the vWF-positive endothelial cells were located on the intima consistent with intact endothelial cells. Beneath the endothelial cells, alpha-SMA-positive smooth muscle cells were distributed. The harvested vessels displayed formation of tunica intima (endothelial cells) and tunica medulla (smooth muscle cell) layers. We also examined the physiological properties of the vessels 12 months post-transplantation using a wire myograph system. The transplanted vessels contracted upon addition of norepinephrine and relaxed upon addition of sodium nitroprusside as well as the native vessels. In conclusion, the acellular vessels prepared with hyperosmotic electrolytic solution showed excellent and long-term patency, which may be related to the successful preservation of vascular ECM. In addition, the acellular vessels revealed the intima/medulla regeneration with the physiological contraction-relaxation functions in response to the each substance.