Fibrin-Based Engineered Vascular Tissues as Platforms for Cellular Studies and Disease Modeling

Vascular tissue engineering (VTE) is an emerging alternative therapeutic intervention strategy to treat diseases such as atherosclerosis. While the ultimate goal of VTE is designing tissues to serve as graft substitutes, they can also serve as powerful tools to study tissue and disease development and drug discovery. In this work, engineered vascular tissues from fibrin gel, mouse embryonic multipotent progenitor cell line (10T1/2 cells), and rat embryonic thoracic artery smooth muscle cells (A-10 cells) were used as models to study the Notch signaling pathway and vascular calcification. The 10T1/2 cells were successfully differentiated into vascular smooth muscle cells with TGFβ1 treatment and compacted the tubular gel significantly owing to the contractile cytoskeletal stress fibers. Notch signaling studies in engineered vascular tissues from A-10 cells demonstrated cis-inhibition while 10T1/2 cells activated Notch and its downstream targets Hes-1 and the smooth muscle α-actin genes. The results from the calcification studies showed that vascular tissues fabricated from both progenitor and differentiated 10T1/2 cells calcified in response to high inorganic phosphate concentrations and expressed the osteopontin protein. Treatment of the tissues with a model therapeutic agent, Vitamin K, led to the reduction of calcium deposits and osteopontin expression, suggesting its potential protective role. In addition, vitamin K treated engineered tissues resulted in the restoration of smooth muscle cells contractile markers. The effect of elastin degradation on calcification was simulated using exogenous elastin and showed that while elastin alone did not impact the undifferentiated tissues, it led to an increase in osteogenic markers in the differentiated counterparts. This work also investigated the role of endothelial cell vimentin in the regulation of Notch signaling and neovascularization in coculture tissue models. The preliminary results showed that vimentin might enhance the Notch signaling strength since the ...