Study on tissue engineered patch replacing segment of the canine abdominal aorta

Ovbective To evaluate the feasibility of a tissue engineered patch constructed by a new copolymer of p(3HB-co-3HH) and polyurethane(PU) as in partial aortic replacement. Methods The autologous cell-polymer scaffold were used to replace 2.0～ 2.5cm abdominal aortic segments in dogs (group TE,n=6). The patches were seeded with 1×10 7 myofibroblasts each day for 4 days,and then 1×10 7 endothelial cells were seeded onto the scaffold. After 48 hours' incubation,the cell-polymer scaffolds were implanted to replace a segment of canine abdominal. In the control group (n=4),aortic segments were replaced with acellular polymer patches. No anticoagulation agent was used. At 2nd,4th,8th,12th,24th,and 48th weeks after operation,the seeded group animals were killed. The control group animals were killed at 4th,12th,24th,and 48th weeks. Explanted patches were examined histologically with scanning electron microscopy,and biochemically. Results In the group of TE patches,the tissue-engineered patches were covered with endothelium-like tissue macroscopically,and there was no thrombus formation on any of the specimens. Histological staining showed uniform layered tissue with endothelium and laminated fibrous tissue with collagen as predominant extracellular matrix. A confluent smooth surface was observed by scanning electron microscopy. An increase in the content of collagen and elastin was observed,and at 48th weeks after operation and their contents equaled to the level of native aorta. There was no endothelium formation in the acellular control,the collagen and elastin content were also smaller than that of the TE groups. Conclusion The autologous aortic grafts with biological characteristics resembling the native aorta can be created by using TE approach.