Kira Lynch

Venous valves in the legs regulate blood flow to the heart. Chronic venous insufficiency (CVI) is a condition that results when these valves fail and allow blood to pool in the legs. Tranquillo Laboratory is working on a vein valve made from a biologically-engineered matrix on a nitinol stent that will provide a long-term solution to CVI. In this study, two molds for tissue-engineered sinuous vein valve stents were 3D printed using SolidWorks. The thickness of tissue coating on the stent is determined by the space between the inner and outer mold along with gel compaction during incubation. Thus, the mold gap was optimized. Prototypes 1 and 2 had mold gaps of 2mm and 4mm respectively. They were cast with dermal fibroblast cells in a fibrin gel and the tissue on the stents were examined after 3 days of incubation. The tissue on the stent from Prototype 1 was found to be too thin and contained holes in the stent struts. Prototype 2 produced a desirable tissue thickness, no holes and minimal thinning on the leaflets. Further testing was conducted with two mock vein valves, one made from latex and one from engineered tissue sheets. The materials were sewed on an oval stent to evaluate function during cyclic flow in a pulse duplicator system (Vivitro Lab). Flow testing demonstrated desirable opening and closing of the valve during the cycle, establishing the stent design as appropriate for developing venous valves.