Tissue-engineered blood vessels in pediatric cardiac surgery

Pediatric cardiovascular surgeons often encounter patients requiring surgical intervention utilizing foreign materials to repair complex lesions. However, the materials that are commonly used lack growth potential, and long-term results have revealed several material-related failures, such as stenosis, thromboembolization, calcium deposition, and risk of infection. To solve these problems, in particular for children who require the implantation of dynamic material with growth potential, we sought to develop optimal filling materials with biocompatibility and growth potential. Previously, we reported the advantages of tissue-engineered vascular autografts (TEVAs) in animal models and in human clinical applications utilizing autologous cells and biodegradable scaffolds. The key benefits from utilizing such scaffolds is that they degrade in vivo, thereby avoiding the long-term presence of foreign ma-terials, and the seeded cells proliferate and differentiate to construct new tissue.Recent studies have demonstrated the existence of bone marrow-derived endothelial pro-genitor cells that contribute to vasculogenesis and angiogenesis and the successful endothelialization of artificial grafts using bone marrow cells. We provided evidence that bone marrow cells as a source for seeding onto a biodegradable scaffold are useful and that seeded cells contribute to the histogenesis of TEVAs. Therefore, we applied this technique in clinical trials with good results. In this review article, we provide an overview of our work developing "tissue-engineered blood vessels" created by utilizing autologous mononuclear bone marrow cells.