ADVANCES IN TISSUE ENGINEERING OF BLOOD-VESSELS AND OTHER TISSUES

Tissue engineering is a new and rapidly expanding field, in which tech niques are being developed for culturing a variety of tissues both in vitro and in vivo using polymer 'scaffolds' to support tissue growth. Polymer scaffolds used in tissue engineering are generally biodegradab le, often involving compounds which are already approved for human imp lantation. In some cases, these polymers may be chemically modified to exhibit selective cell adhesion properties, which enhance cell attach ment and subsequent tissue growth. Many cell types have been successfu lly cultured on these scaffolds, including smooth muscle cells, endoth elial cells, hepatocytes and chondrocytes. Tissue engineering holds th e potential for the in vitro development of autologous or allogeneic t ransplantable vascular conduits. Each year in the USA, there are appro ximately 1.4 million procedures performed which require arterial prost heses. Most of these procedures are in small calibre (<6 mm) vessels, for which synthetic graft materials are not generally suitable. While autologous venous or arterial vessels are gener ally used, not all pat ients possess adequate conduit for revascularization. Tubular scaffold s have been specially designed for culturing small calibre arteries in vitro. Bovine aortic vascular cells were seeded and cultured on these polymer scaffolds, and grown under conditions of pulsatile pressure a nd intra-luminal flow. To minimize contamination during the weeks of t issue culture required to produce an arterial prosthesis, a sterile in cubator system was developed. Preliminary studies have achieved good c ell densities of both smooth muscle cells and endothelial cells on bio degradable polymer scaffolds.