Vascular tissue engineering vessels

Significant eftort is now focusing on tissue-engineered vessels and heart valves. The history of this effort is found in the seeding or culturing of endothelium on synthetic vascular prostheses. The clinical outcomes did not justify continued development. However, rrew technology allows vascular tissue to be formed on scaffolds of either synthetic or resorbable materials. The awareness that endothelium alone was not suitable has led to the evolution of techniques to recreate the vascular tissue utilizing multiple cells types. - This approach utilizes the cell types expected in final structure, e.g., endothelium, smooth muscle cells, and fibroblasts, or pluripotential cells such as stem cells. 

The development of a functional TEVG is likely to require the constmction of an intima and media composed of endothelial and smooth muscle cells. Limitations imposed by immunogenicity will probably require that autologous cells be used, so the majority of studies to date have used differentiated smooth muscle and endothelial cells isolated from harvested blood vessels. But problems with donor-site morbidity and the performance of these cell types in engineered tissues have led to the consideration of alternative cell sources. Recent advances in stem cell biology may lead to suitable progenitors that can be effectively differentiated into endothelial and smooth muscle cells for use in vascular tissue engineering. 

Another example was done by Opitz et al. They utilized P4HB scaffolds to produce viable ovine blood vessels, and then implanted the blood vessels in the systemic circulation of sheep. Enzymatically derived vascular smooth muscle cells (vSMC) were seeded on the scaffolds both under pulsatile flow and static conditions. Mechanical properties of bioreactor-cultured blood vessels which were obtained from tissue engineering approached those of native aorta. 

Opitz F, Schenke-Layland K, Richter W, Martin DP, Degenkolbe I, Wahlers T, and Stock UA. Tissue engineering of ovine aortic blood vessel substitutes using applied shear stress and enzymatically derived vascular smooth muscle cells. Ann Biomed Eng, 2004, 32, 212-222. 

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