Tissue-engineered graft constructed by bone marrow mesenchymal stem cells and vascular acellular matrix / 中国组织工程研究

ABSTRACT

BACKGROUND: At present, the commercial artificial small vascular grafts (diameter < 6 mm) are still unsatisfactory, due to poor blocompatibility and low long-term patency rate. Therefore, finding a vascular substitute with normal biological function and studying construction and function of tissue-engineered blood vessel have become hot topics recently.OBJECTIVE: To construct a novel tissue-engineered blood vessel by rabbit bone marrow mesenchymal stem cells (MSCs) and vascular acellular matrix, and to investigate the biocompatibility and patency rate of tissue-engineered blood vessels.DESIGN, TIME AND SETTING: An in vitro randomized controlled study at level of cytology and histopathology was performed at the Laboratory of Affiliated Drum Tower Hospital of Nanjing University Medical School from January 2006 to June 2008.MATERIALS The decellularized vascular acellular matrix was obtained by a detergent-enzymatic procedure. MSCs from rabbits were isolated using density gradient centrifugation method and cultured in culture flasks coated with fibronectin. Subsequently, the expanded MSCs were seeded on the decellularized scaffolds, and then co-cultured in the self-made bioreactor to construct the tissue-engineered blood vessels.METHODS: Sixty rabbits were randomly divided into three groups. A1.0-cm abdominal aorta was sheared, and a tissue-engineered blood vessel was transplanted on the abdominal aorta using 8/0 polypropylene thread. Tissue-engineered blood vessel group Tissue-engineered blood vessel was considered as the transplanted vessel; vascular acellular matrix groupXenoma artery treated by vascular acellular matrix was considered as the transplanted vessel; xenoma artery group Fresh xenoma artery was considered as the transplanted vessel.MAIN OUTCOME MEASURES: Immunocytochemical staining was used to identify the cultured MSCs. After 3 months of transplantation, the grafts were retrieved for digital subtraction angiography, pathological test and scanning electron microscope examination.RESULTS: Rabbits MSCs presented a whirlpool-like appearance at 8 days after culture. The immunocytochemistry results were consistent with the phenotype of MSCs. After high proliferation, MSCs were seeded onto the vascular acellular matrix for 12 days,and seed cells attached to well in the lumen of blood vessels. Three months after implantation, the patency rate was 90% of tissue-engineered blood vessel group and 80% of vascular acellular matrix group, which was superior to xenoma artery group (25%). At three months after transplantation, HE staining and scanning electron microscope demonstrated that internal, middle,and external membrane were clearly observed in the tissue-engineered blood vessel group, and the membrane morphology was similar to normal artery. The endothelial cells were covered completely. However, the endothelial cells were not covered completely in the vascular acellular matrix group, while mural thrombosis, mild proliferation of intima, and inflammatory cell infiltration were observed. The intima was thick and necrotic in the xenoma artery group, while lumens were stenotic and accompanied with a certain degree of thrombus organization.CONCLUSION: This study provides a new strategy to develop a tissue-engineered blood vessel with excellent biocompatibility and high patency rate constructed by rabbit MSCs and vascular acellular matrix.