Abstract 360: Development of a Human Tissue-Engineered Blood Vessel from Adipose-Derived Stem Cells

There exists a clear need for alternative sources of small-diameter vascular grafts for treating the millions of patients who suffer from cardiovascular disease each year. Bypass surgery or replacement of defective vessels is often required to treat coronary heart disease, but there is a limited supply of suitable autologous grafts, and synthetic grafts are ineffective for replacement of small-diameter vessels. Inherent thrombogenicity, compliance mismatch, and limited patency rates are all complications with current options. Tissue engineering has the potential to overcome these limitations by producing a readily-available vascular graft completely from biological material. It is the objective of this study to fabricate such a small-diameter tissue engineered blood vessel (TEBV) by using the human amniotic membrane as a mechanically-sound biological substrate. Our technology begins by differentiating adipose-derived stem cells into smooth muscle cells (SMCs) and seeding them onto a flat sheet of the amniotic membrane. We assessed our hypothesis that several types of SMCs can successfully attach and proliferate on this membrane by fluorescently staining cell nuclei with DAPI and characteristic SMC actin filaments with phallotoxins. After 7 days in static culture, the cell-seeded sheet was wrapped around a 3mm O.D. removable mandrel with 6-7 revolutions to develop a tubular construct with architecture akin to that of a muscular artery’s tunica media layer. After a 2 week static culture period, the TEBV was characterized for its biochemical and mechanical properties. We examined the contraction of the vessel in response to carbachol, a specific agonist for SMCs, and compared our results with the contraction of porcine coronary arteries. Burst pressure and elastic modulus tests were also performed. The mechanical integrity of this construct can be further improved upon its exposure to appropriate physiological conditions in a perfusion bioreactor. We show that adipose-derived endothelial cells (ECs) can be also be seeded into the lumen of this construct to prevent platelet adhesion. In conclusion, we have developed a small-diameter TEBV with off-the-shelf availability using a completely biological material seeded with patient-own stem cells.