Preliminary fabrication of tissue engineered veins containing valves using bone marrow mesenchymal stem cells and biodegradable scaffolds in vitro / 中国组织工程研究

ABSTRACT

BACKGROUND:Chronic venous insufficiency is a major health problem worldwide. Clinical treatments include venous valve repair and venous segment containing valve transplantation. However, these are invasive procedures, and the supply of vein containing valves is limited. Significant progress in the fields of tissue engineering and regenerative medicine has been made towards the creation of tissue engineered vascular grafts for the repair of damaged or malformed vessels. It has been reported that using tissue engineering, a tissue engineered vein containing valves constructed with self-derived endothelial cells and al ogeneic acellular matrices can provide the complex physiological valve structure and mechanical stability, but this elicited an immunogenic response. OBJECTIVE:To create a viable and functional vein containing valves, which has the ability to grow, repair, and imitate natural tissues. METHODS:Bone marrow mesenchymal stem cells were obtained from Beagle dogs by density gradient centrifugation and adherence methods. Bone marrow mesenchymal stem cells were cultured in vitro. Fol owing isolation and culture the cells were examined using flow cytometry and identified by direct induction towards the osteogenic and adipogenic lineages. We fabricated biodegradable venous scaffold containing valves using the method of injection molding combined with thermal y induced phase separation. Based on the self-made cast, a three-dimensional biodegradable vein scaffold containing valves was constructed from poly(lactic-co-glycolic acid). Morphological structure was tested. Bone marrow mesenchymal stem cells were used as seed cells to be seeded onto the lumen of the tissue engineered vein scaffold containing valves in vitro and then incubated for 2 weeks. RESULTS AND CONCLUSION:Scanning electron microscopy images showed that the scaffold demonstrated sufficient porosity. Cultured cells expressed mesenchymal cellmarkers, CD44 and CD29, but did not express hematopoietic cellmarkers, CD34 and CD45 at the same time point. Scaffolds were nontoxic to cells and were favorable for the growth and migration of bone marrow mesenchymal stem cells. cells attached on the surface of poly(lactic-co-glycolic acid) scaffolds formed a confluent layer after incubation. The cellular constructs were tested in vitro, and the valve leaflets were functional y capable of opening and closing when stimulated. These results suggested that the tissue engineered vein containing valves have been successful y constructed by using a three-dimensional poly(lactic-co-glycolic acid) scaffold and bone marrow mesenchymal stem cells as seed cells. Tissue engineered vein containing valves is potential y useful for the substitution and regeneration of vein valves.