Toward an endothelial-cell covered mechanical valve; surface re-engineering and bioreactor testing of mechanical heart valves

Mechanical valve replacements for diseased heart valves have excellent long-term durability, but necessitate a lifetime anticoagulation regimen. We aimed to create a more hemocompatible device by modifying the leaflet surfaces to promote adherence and retention of endothelial cells under physiological shear forces.St. Jude Medical mechanical valves were autoclaved, plasma treated, coated with a collagen/fibronectin solution, and seeded with porcine aortic endothelial cells. The next day, the valves were placed in a custom-made bioreactor where pressures were gradually increased until reacingpulmonary or aortic pressures. Conditioning continued for 7 days. Cellular retention, viability, and morphology were investigated using Live/DEAD® staining, CD-31 immunofluorescence, and scanning electron microscopy.Results demonstrated successful adhesion of the collagen/fibronectin substrate to the pyrolytic carbon surface. Complete endothelial coverage of the leaflet surface in the static control group indicates that our surface modification approach created a suitable environment for the cells to attach, proliferate, and remain viable. Moreover, after 7 days of dynamic conditioning at pulmonary pressures, a significant portion of the endothelial cells remained adherent to valve surfaces, improved cell coverage over static controls, remained viable, increased cell-cell interactions, and maintained expression of CD31. Similar results were seen at aortic pressures but with increased cell removal due to higher shear stresses. Further work is needed to improve cell retention in areas of high shear stress, but surface modification and endothelial cell coating may ultimately aid in limiting coagulation and reduce the need for anticoagulation medication in patients receiving mechanical heart valve implants.

Sierad, Leslie Neil, Eliza Laine Shaw, Ryan Launius, Shannon McBride, Cassie Storholt, Ryan Poole, Daniel Spence, Katie Miller, Lauren Sosdian, Kaity Allen

Challenges Regener Med





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