Abstract 15382: Engineering the Adventitia to Build a Better Vascular Graft
Introduction: To treat atherosclerosis, a patient’s own blood vessels are harvested for bypass surgery, creating further injury. Engineered vessels could save patients from undue harm. The outer layer of a blood vessel, or adventitia, provides strength. In most engineered vessels, a polymer tube is used to approximate the role of the adventitia. However, polymer grafts have proven issues with patency. Our hypothesis is that a completely cellular adventitia will decrease immune response and improve patency.
Methods: To generate a cellular adventitia, we used our recently developed method for creating rings of tissue which are then stacked to form a tubular, vascular structure. Human dermal fibroblasts were plated into a culture dish with a center plastic post. Cell attachment was controlled using a hydrogel substrate. Once the cell monolayer forms, it detaches and aggregates around the center post forming a ring. To strengthen the rings, ascorbic acid and/or TGF-beta were added. Both factors stimulate production of collagen and elastin, proteins governing strength and elasticity of blood vessels.
Results: Ascorbic acid produced thin rings (~157 um). TGF-beta produced thicker rings (~483 um), though lacked structure. The addition of both ascorbic acid and TGF-beta resulted in the most stable rings (~386 um). PCR analysis showed that collagen and elastin production was increased with either factor, and highest when combined. Ascorbic acid resulted in the highest amount of elastin expression, demonstrated in the structure of these rings. TGF-beta increased collagen production, however elastin was low, evidenced by lower expression of elastin and loose rings. Stimulation by both factors produced thick, tight rings indicative of the adventitia.
Conclusions: This work shows that a completely cellular tunica adventitia can be engineered. Through our continued work on strengthening our engineered adventitia, engineered vascular grafts could become more functional.
Author Disclosures: M.T. Lam: None. C. Pinnock: None. B. Patel: None.
- © 2016 by American Heart Association, Inc.