The effect of cyclic strain on embryonic stem cell-derived cardiomyocytes.

Cardiomyocytes in the body are subjected to cyclic mechanical strain induced by the rhythmic heart beating. In this study, we tested the hypothesis that cyclic strain promotes cardiomyogenesis of embryonic stem cell-derived cardiomyocytes (ESCs). ESCs cultured on elastic polymer [poly(lactide-co-caprolactone), PLCL] scaffolds subjected to cyclic strain in vitro displayed elevated cardiac gene expression compared to unstrained controls. Six weeks after implantation into infarcted rat myocardium, the elastic cardiac patches (ESC-seeded PLCL scaffolds) showed reduced fibrotic tissue formation, likely due to a combination of lower apoptotic activity, higher vascular endothelial growth factor (VEGF) expression, and more extensive angiogenesis in the strained versus unstrained control [ESC-seeded, non-elastic poly(lactide-co-glycolide) scaffolds] patches. Importantly, cardiac gene expression was upregulated in the elastic patches compared to control, with evidence for cardiomyocyte-specific microstructures including myofibrillar bundles and Z-lines. This study shows that the use of an elastic polymer scaffold designed to permit mechanical strain transduction as a cell transplantation vehicle significantly increases cardiomyogenesis of the implanted ESCs.

Effects of False Lumen Procedures on Aorta Remodeling of Chronic DeBakey IIIb Aneurysm.

BACKGROUND: Although thoracic endovascular aortic repair is regularly used to treat chronic DeBakey type IIIb aneurysms, persistent retrograde flow into the false lumen through distal reentry tears is a common cause of failure. We sought to determine the safety and efficacy of the false lumen procedure (FLP) for aortic remodeling with chronic DeBakey IIIb aneurysms. METHODS: From 2012 to 2015, 25 patients with chronic DeBakey IIIb aneurysms underwent FLP using vascular plugs, stent grafts, coils, or glues. The FLP was performed as an adjunctive procedure after initial thoracic endovascular aortic repair in 9 patients, in combination with initial thoracic endovascular aortic repair in 13 patients, and as an isolated procedure in 3 patients. All patients were followed up for a mean duration of 10 months after the FLP. Outcomes included the degree of thrombosis and diameter change in the true lumen and false lumen. Diameters were measured at three levels: left subclavian artery, pulmonary artery bifurcation, and abdomen (celiac artery). RESULTS: No spinal cord injury, renal failure, or 30-day mortality was observed. Complete false lumen thrombosis after FLP was observed in 20 patients (80%). Compared with before FLP, the mean false lumen diameter for each level (before 22.23 ± 10.18 mm versus after 17.56 ± 10.84 mm; p < 0.001) significantly decreased, whereas the mean true lumen diameter for each level (20.45 ± 5.33 mm versus 25.12 ± 5.60 mm, p < 0.001) increased. CONCLUSIONS: False lumen procedures were safe, promoted complete thrombosis, and had favorable aortic remodeling in patients with chronic DeBakey IIIb aneurysms.