Porcine radial artery decellularization by high hydrostatic pressure.

Many types of decellularized tissues have been studied and some have been commercially used in clinics. In this study, small-diameter vascular grafts were made using HHP to decellularize porcine radial arteries. One decellularization method, high hydrostatic pressure (HHP), has been used to prepare the decellularized porcine tissues. Low-temperature treatment was effective in preserving collagen and collagen structures in decellularized porcine carotid arteries. The collagen and elastin structures and mechanical properties of HHP-decellularized radial arteries were similar to those of untreated radial arteries. Xenogeneic transplantation (into rats) was performed using HHP-decellularized radial arteries and an untreated porcine radial artery. Two weeks after transplantation into rat carotid arteries, the HHP-decellularized radial arteries were patent and without thrombosis. In addition, the luminal surface of each decellularized artery was covered by recipient endothelial cells and the arterial medium was fully infiltrated with recipient cells.

Application of a vacuum pressure impregnation technique for rehydrating decellularized tissues.

Most of the clinically available decellularized tissues are preserved in a freeze-dried state. Freeze-dried (FD) tissues can be preserved for long term, although a rehydration process is necessary before use. Currently, an immersion method is most commonly used in clinical procedures, but it is difficult for complicated and thick structure tissue rehydration. In this study, we tried to apply a vacuum pressure impregnation (VPI) technique for FD tissue rehydration. The water content of decellularized tissues can reach the water content of native tissues within 30 min using VPI, whereas it took 6 h to reach the same water content using the immersion method. Furthermore, heparin rehydrated aortas by VPI had more heparin release at each time point and therefore appeared more anticoagulant activity. We found that the VPI treatment promotes solution infiltration into materials, achieves complete rehydration of the decellularized tissues, and deep infiltration of heparin into the decellularized tissues, suggesting that VPI treatment could be applied as a rehydration method for biological materials.

Effect of treatment temperature on collagen structures of the decellularized carotid artery using high hydrostatic pressure.

Decellularized tissues have attracted a great deal of attention as regenerating transplantation materials. A decellularizing method based on high hydrostatic pressure (HHP) has been developed, and the preparation of many types of decellularized tissues has been investigated, including aorta, cornea, and dermis. The preparation of a small-diameter vascular graft was studied using a carotid artery from the viewpoint of collagen denaturation and leakage. After HHP, the carotid artery was washed at two washing temperatures (37 and 4°C). Histological evaluation, collagen content measurement and circular dichroism (CD) measurement indicated that the washing temperatures clearly affected the collagen structure of the decellularized carotid artery. The amount of collagen decreased in the carotid artery decellularized by HHP washed at 37°C (HHP/37°C). On the other hand, the amount and structure of collagen were preserved in the carotid artery washed at 4°C after HHP (HHP/4°C). In rat carotid artery syngeneic transplantation, the HHP/37°C decellularized carotid artery occluded after 2 weeks, but the HHP/4°C decellularized one did not. These results indicate that collagen denaturation and leakage of the decellularized carotid artery affect the in vivo performance of the carotid artery.