Three-dimensional poly-(ε-caprolactone) nanofibrous scaffolds directly promote the cardiomyocyte differentiation of murine-induced pluripotent stem cells through Wnt/ß-catenin signaling.

BACKGROUND: Environmental factors are important for stem cell lineage specification, and increasing evidence indicates that the nanoscale geometry/topography of the extracellular matrix (ECM) directs stem cell fate. Recently, many three-dimensional (3D) biomimetic nanofibrous scaffolds resembling many characteristics of the native ECM have been used in stem cell-based myocardial tissue engineering. However, the biophysical role and underlying mechanism of 3D nanofibrous scaffolds in cardiomyocyte differentiation of induced pluripotent stem cells (iPSCs) remain unclear. RESULTS: Here, we fabricated a 3D poly-(ε-caprolactone) (PCL) nanofibrous scaffold using the electrospinning method and verified its nanotopography and porous structure by scanning electron microscopy. We seeded murine iPSCs (miPSCs) directly on the 3D PCL nanofibrous scaffold and initiated non-directed, spontaneous differentiation using the monolayer method. After the 3D PCL nanofibrous scaffold was gelatin coated, it was suitable for monolayer miPSC cultivation and cardiomyocyte differentiation. At day 15 of differentiation, miPSCs differentiated into functional cardiomyocytes on the 3D PCL nanofibrous scaffold as evidenced by positive immunostaining of cardiac-specific proteins including cardiac troponin T (cTnT) and myosin light chain 2a (MLC2a). In addition, flow cytometric analysis of cTnT-positive cells and cardiac-specific gene and protein expression of cTnT and sarcomeric alpha actinin (α-actinin) demonstrated that the cardiomyocyte differentiation of miPSCs was more efficient on the 3D PCL nanofibrous scaffold than on normal tissue culture plates (TCPs). Furthermore, early inhibition of Wnt/ß-catenin signaling by the selective antagonist Dickkopf-1 significantly reduced the activity of Wnt/ß-catenin signaling and decreased the cardiomyocyte differentiation of miPSCs cultured on the 3D PCL nanofibrous scaffold, while the early activation of Wnt/ß-catenin signaling by CHIR99021 further increased the cardiomyocyte differentiation of miPSCs. CONCLUSION: These results indicated that the electrospun 3D PCL nanofibrous scaffolds directly promoted the cardiomyocyte differentiation of miPSCs, which was mediated by the activation of the Wnt/ß-catenin signaling during the early period of differentiation. These findings highlighted the biophysical role of 3D nanofibrous scaffolds during the cardiomyocyte differentiation of miPSCs and revealed its underlying mechanism involving Wnt/ß-catenin signaling, which will be helpful in guiding future stem cell- and scaffold-based myocardium bioengineering.

Biodegradable polymer-coated versus durable polymer-coated sirolimus-eluting stents: the final 5-year outcomes of the I-LOVE-IT 2 trial.

AIMS: This analysis presents the final five-year results of the I-LOVE-IT 2 trial, a non-inferiority study comparing a biodegradable polymer (BP) sirolimus-eluting stent (SES) with a durable polymer (DP) SES in patients with coronary artery disease. METHODS AND RESULTS: Overall, 2,737 Chinese patients eligible for coronary stenting were treated with BP-SES or DP-SES in a 2:1 ratio. Patients who were randomised to the BP-SES group were additionally re-randomised to receive either six-month or 12-month dual antiplatelet therapy (DAPT) in a 1:1 ratio. The primary endpoint was 12-month target lesion failure (TLF: cardiac death, target vessel myocardial infarction (MI), or clinically indicated target lesion revascularisation). At five years, the overall follow-up rate was 90.8%, and the cumulative incidence of TLF as the primary endpoint was similar between BP-SES and DP-SES (hazard ratio [HR] 1.01, 95% confidence interval [CI]: 0.79 to 1.28), as was that for the patient-oriented composite endpoint (PoCE: all-cause death, all MI and any revascularisation) (HR 1.03, 95% CI: 0.86 to 1.23), or definite/probable stent thrombosis (ST) (HR 0.91, 95% CI: 0.70 to 1.77). Cumulative events were also similar between the six-month DAPT and 12-month DAPT groups after BP-SES implantation. CONCLUSIONS: I-LOVE-IT 2 showed that the five-year safety and efficacy of BP-SES and DP-SES were similar, as were those between six months and 12 months of DAPT after BP-SES implantation.