Fibrin is a biopolymer that has been used in a variety of biomaterial, cell delivery and tissue engineering applications. The enzyme thrombin catalyzes the formation of fibrin microfibrils, which form a three-dimensional mesh in which cells can be directly embedded at the time of gel formation. In this study, fibrin hydrogels containing vascular smooth muscle cells were created using varying concentrations of thrombin. Over 7 days in culture, all gels decreased in volume as the fibrin matrix compacted, and the degree of gel compaction increased as thrombin concentration decreased. The material modulus and ultimate tensile stress of the gels also increased with decreasing thrombin concentration. Addition of thrombin to similar constructs made using collagen Type I did not show an effect on gel compaction or mechanical properties, suggesting that these effects were a result of thrombin's action on fibrin polymerization, and not cellular functions. Cell proliferation in fibrin hydrogels was not significantly affected by thrombin addition. Matrix examination using scanning electron microscopy showed increasing fibrin fiber diameters as thrombin concentration decreased. Confocal microscopic imaging of the actin cytoskeleton showed that cell morphology on twodimensional substrates of fibrin showed marked changes, with higher thrombin concentrations producing cells with longer cellular projections. However, these morphological changes were not as apparent in cells embedded in three-dimensional (3-D) matrices, in which cells exhibited a similar morphology independent of thrombin concentration. These results relate features of the matrix and cellular components of 3-D fibrin constructs to mechanical properties, and contribute to the understanding of structure-function relationships in cell-seeded, 3-D protein hydrogels.

Background: Owing to the differential propensity for bleeding and ischemic events with response to antiplatelet therapy, the safety and effectiveness of potent P2Y12 inhibitor ticagrelor in East Asian populations remain uncertain. Methods: In this multicenter trial, 800 Korean patients hospitalized for acute coronary syndromes with or without ST elevation and intended for invasive management were randomly assigned to receive, in a 1:1 ratio, ticagrelor (180 mg loading dose, 90 mg twice daily thereafter) or clopidogrel (600 mg loading dose, 75 mg daily thereafter). The primary safety outcome was clinically significant bleeding (a composite of major bleeding or minor bleeding according to PLATO (Platelet Inhibition and Patient Outcomes) criteria at 12 months. Results: At 12 months, the incidence of clinically significant bleeding was significantly higher in the ticagrelor group than in the clopidogrel group (11.7% [45/400] vs 5.3% [21/400]; hazard ratio [HR], 2.26; 95% confidence interval [CI], 1.34 to 3.79; P =0.002). The incidences of major bleeding (7.5% [29/400] vs 4.1% [16/400], P =0.04) and fatal bleeding (1% [4/400] vs 0%, P =0.04) were also higher in the ticagrelor group. The incidence of death from cardiovascular causes, myocardial infarction, or stroke was not significantly different between the ticagrelor group and the clopidogrel group (9.2% [36/400] vs 5.8% [23/400]; HR, 1.62; 95% CI, 0.96 to 2.74; P =0.07). Overall safety and effectiveness findings were similar with the use of several different analytic methods and in multiple subgroups. Conclusions: In Korean acute coronary syndrome patients intended to receive early invasive management, standard-dose ticagrelor as compared with clopidogrel was associated with a higher incidence of clinically significant bleeding. The numerically higher incidence of ischemic events should be interpreted with caution, given the present trial was underpowered to draw any conclusion regarding efficacy. Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT02094963.

Virtual coronary stenting of CT-derived computational models is feasible, and this novel noninvasive technology may be useful in predicting functional outcome after coronary stenting. (Virtual Coronary Intervention and Noninvasive Fractional Flow Reserve [FFR]; NCT01478100).

ImportanceIn patients with coronary artery disease, some guidelines recommend initial statin treatment with high-intensity statins to achieve at least a 50% reduction in low-density lipoprotein cholesterol (LDL-C). An alternative approach is to begin with moderate-intensity statins and titrate to a specific LDL-C goal. These alternatives have not been compared head-to-head in a clinical trial involving patients with known coronary artery disease.ObjectiveTo assess whether a treat-to-target strategy is noninferior to a strategy of high-intensity statins for long-term clinical outcomes in patients with coronary artery disease.Design, Setting, and ParticipantsA randomized, multicenter, noninferiority trial in patients with a coronary disease diagnosis treated at 12 centers in South Korea (enrollment: September 9, 2016, through November 27, 2019; final follow-up: October 26, 2022).InterventionsPatients were randomly assigned to receive either the LDL-C target strategy, with an LDL-C level between 50 and 70 mg/dL as the target, or high-intensity statin treatment, which consisted of rosuvastatin, 20 mg, or atorvastatin, 40 mg.Main Outcomes and MeasuresPrimary end point was a 3-year composite of death, myocardial infarction, stroke, or coronary revascularization with a noninferiority margin of 3.0 percentage points.ResultsAmong 4400 patients, 4341 patients (98.7%) completed the trial (mean [SD] age, 65.1 [9.9] years; 1228 females [27.9%]). In the treat-to-target group (n = 2200), which had 6449 person-years of follow-up, moderate-intensity and high-intensity dosing were used in 43% and 54%, respectively. The mean (SD) LDL-C level for 3 years was 69.1 (17.8) mg/dL in the treat-to-target group and 68.4 (20.1) mg/dL in the high-intensity statin group (n = 2200) (P = .21, compared with the treat-to-target group). The primary end point occurred in 177 patients (8.1%) in the treat-to-target group and 190 patients (8.7%) in the high-intensity statin group (absolute difference, –0.6 percentage points [upper boundary of the 1-sided 97.5% CI, 1.1 percentage points]; P < .001 for noninferiority).Conclusions and RelevanceAmong patients with coronary artery disease, a treat-to-target LDL-C strategy of 50 to 70 mg/dL as the goal was noninferior to a high-intensity statin therapy for the 3-year composite of death, myocardial infarction, stroke, or coronary revascularization. These findings provide additional evidence supporting the suitability of a treat-to-target strategy that may allow a tailored approach with consideration for individual variability in drug response to statin therapy.Trial RegistrationClinicalTrials.gov Identifier: NCT02579499

The VH-IVUS analysis shows that post-PCI cTnI elevation occurs in lesions with a large necrotic core area. The VH-IVUS may play an important role in detecting which lesions are high risks for myocardial necrosis after PCI.