ABSTRACT
BACKGROUND:Due to limited sources,poor hemocompatibility and poor anticoagulation performance,small-diameter tissue-engineered blood vessels cannot be applied in clinical practice.OBJECTIVE:To explore the physicochemical and mechanical properties of sheep carotid arteries after the decellularization in order to find appropriate materials for the preparation of tissue-engineered blood vessels.METHODS:Fresh carotid arteries from sheep were randomly divided into two groups:control group,in which,the sheep carotid arteries were cryopreserved for use after trimming and cleaning;experimental group,in which,after trimming and cleaning,the carotid arteries were decallularized by Triton X-100.sodium deoxycholate and EDTA for 24 hours,rinsed for 72 hours,digested with RNA/DNA enzymes for 24 hours,rinsed for 24 hours and reserved for later use.In both groups,blood samples were subjected to hematoxylin-eosin staining,collagen fiber staining,elastic fiber dyeing,and electron microscopy observation.The physical and chemical properties of the blood vessels are tested by tensile strength,wall tension and thickness.RESULTS AND CONCLUSION:(1) The collagen fibers in both two groups were neat and compact in alignment,with no obvious fracture.(2) Hematoxylin-eosin staining showed that:in the control group,the nuclei were distributed in the inner membrane,middle lamella and outer membrane of the vessels,and the fibers ran regularly;in the experimental group,the fibers ran in order but loosely,and there were no nuclei in the inner membrane,middle lamella and outer membrane of the vessels.(3) Elastic fibers in the control group were regular in alignment and mainly distributed in the middle lamella and outer membrane of the vessels,while in the experimental group,the elastic fibers ran regularly but loosely,and mainly distributed in the middle lamella and outer membrane of the vessels.(4) Under the scanning electron microscope,the originally formed vessels were observed in the experimental group,with no cell residues,and the collagen fibers ran orderly with no fracture and with uniform pore structure.(5) The vessel thickness was lower in the experimental group than the control group (P ＜ 0.01),but the tensile strength showed no difference between the two groups,which was 46.55 kPa in the two groups.To conclude,the decelluarized sheep carotid artery can retain the necessary mechanical properties of the blood vessels after achieving the maximum removal of antigenicity.
ABSTRACT
<p><b>BACKGROUND</b>The application of pulmonary valved conduit to reconstruct the continuity between right ventricles and pulmonary artery is one of the major surgeries. This study aimed to establish an in vivo model of in situ implantation using pulmonary valved conduit in large animals under off-pump condition to validate the long-term effects of artificial pulmonary valved conduit.</p><p><b>METHODS</b>Domesticate juvenile male sheep and tissue-engineered porcine pulmonary valved conduit were used for the experiment: 30 sheep, weighing (15 ± 3) kg (range 13 to 17 kg) were randomly divided into two groups which were all operated under general anesthesia by off-pump surgery (group 1) and left thoracotomy (group 2). Two different off-pump surgical methods were used to perform cannulation in sheep pulmonary artery to replace part of sheep pulmonary artery with pulmonary valved conduit which will work together with sheep pulmonary artery and valves. During the experiments, animal survival, complication rates, operating time and blood loss were recorded to compare the results between groups and to establish a surgical method with minimal invasion, simplicity, safety, and high success rates.</p><p><b>RESULTS</b>In group 1, a total of 15 cases of surgeries were performed, in which two sheep died; the operative mortality was 13.3% (2/15). In group 2, a total of 15 cases of surgeries were performed, and the surgical mortality rate was 0 (0/15). The operation time and blood loss in group 2 was significantly better than that in group 1. The postoperative echocardiograms showed that, after the surgeries by these two methods, the blood flows were normal, and the valves can open and close freely. Autopsy after 6 months showed that the inner wall and the valves of pulmonary valved conduit were smooth with no thrombus formation.</p><p><b>CONCLUSION</b>These two off-pump methods are feasible and safe with fewer traumas; but the second method is better and particularly suitable for the establishment of a juvenile animal model.</p>