Tissue engineering of the vascular system: from capillaries to larger blood vessels

Tissue engineering is a novel approach to the repair of wounded tissues. Application of this technology to the vascular system is important because of the fundamental nutritional role of the vasculature. This perspective is currently being applied to the first tissue-engineered organ: the skin. Knowledge of capillary constitution and factors inducing their formation has led to attempts to induce their formation in reconstructed skin. Such vascular conduits grown in vitro could also benefit the nutrition of tissues and organs in vivo. The paper reviews recent progress in the in-vitro development of vascularised skin and tissue-engineered blood vessels. It points out the necessity of obtaining pure and well-characterised cultures of the different cell populations that are the basic building blocks of the reconstructions. The importance of an adequate cell-culture environment (nutrients and bi- or tri-dimensional scaffolds for cells) for success in elaborating a reconstructed living tissue able to replace the original is emphasised. Engineered tissues can serve not only as tissue replacements but also as in-vitro models for research in organ physiology and physiopathology. These tissues are also attractive vehicles for gene therapy, one of the more promising new methods of disease treatment.