Simulation and optimization of nutrient uptake and biomass formation using a multi-parameter Monod-type model of tobacco BY-2 cell suspension cultures in a stirred-tank bioreactor.

Introduction: Tobacco (Nicotiana tabacum) cv Bright Yellow-2 (BY-2) cell suspension cultures enable the rapid production of complex protein-based biopharmaceuticals but currently achieve low volumetric productivity due to slow biomass formation. The biomass yield can be improved with tailored media, which can be designed either by laborious trial-and-error experiments or systematic, rational design using mechanistic models, linking nutrient consumption and biomass formation. Methods: Here we developed an iterative experiment-modeling-optimization workflow to gradually refine such a model and its predictions, based on collected data concerning BY-2 cell macronutrient consumption (sucrose, ammonium, nitrate and phosphate) and biomass formation. Results and discussion: The biomass formation was well predicted by an unstructured segregated mechanistic Monod-type model as long as the nutrient concentrations did not approach zero (we omitted phosphate, which was completely depleted). Multi-criteria optimization for sucrose and biomass formation indicated the best tradeoff (in a Paretian sense) between maximum biomass yield and minimum process time by reducing the initial sucrose concentration, whereas the inoculation biomass could be increased to maximize the biomass yield or minimize the process time, which we confirmed in calibration experiments. The model became inaccurate at biomass densities > 8 g L-1 dry mass when sucrose was almost depleted. We compensated for this limitation by including glucose and fructose as sucrose hydrolysis products in the model. The remaining offset between the simulation and experimental data might be resolved by including intracellular pools of sucrose, ammonium, nitrate and phosphate. Overall, we demonstrated that iterative models can be used to systematically optimize conditions for bioreactor-based processes.

Iliofemoral artery predilation prior to transfemoral transcatheter aortic valve implantation in patients with aortic valve stenosis and advanced peripheral artery disease.

OBJECTIVES: To investigate the feasibility and safety of percutaneous transluminal angioplasty (PTA) of the iliofemoral arteries (IFA) before transfemoral transcatheter aortic valve implantation (Tf-TAVI) in patients with advanced peripheral artery disease (PAD). BACKGROUND: Although Tf-TAVI represents the access of choice, alternative vascular access routes are preferred for patients displaying advanced PAD. PTA of the IFA represents a less invasive option, broadening the spectrum of patients eligible for Tf-TAVI. METHODS: All patients requiring PTA of the IFA before Tf-TAVI, between 2012 and 2021, were included. Primary efficacy endpoint was the rate of successful transcatheter heart valve (THV) delivery and implantation. Primary safety endpoint was the rate of PTA and access-site-related vascular complications, procedural- and in-hospital complications. RESULTS: Among 2726 Tf-TAVI procedures, 59 patients required IFA predilation. Successful THV delivery and implantation was achieved in 57 (96.6%) patients, respectively. Sheath placement was achieved in 59 (100%) patients with only one minor dissection and no major vascular complications following iliofemoral PTA. Regarding access site complications, two (3.4%) vessel perforations and one (1.7%) vessel rupture were observed, with eight (13.5%) patients requiring unplanned endovascular interventions. There was one intraprocedural death due to THV-induced vessel laceration, while in-hospital all-cause mortality was 8.5% in the present high-risk patient cohort. CONCLUSIONS: Predilation of IFA is safe and effective in patients with advanced PAD. Careful preprocedural planning is paramount in improving procedural safety and efficacy. This strategy has the potential to broaden the spectrum of patients eligible for Tf-TAVI.

Transcatheter Aortic Valve Replacement With Balloon-Expandable Valves: Comparison of SAPIEN 3 Ultra Versus SAPIEN 3.

OBJECTIVES: The aim of this study was to compare outcomes after transcatheter aortic valve replacement (TAVR) with the SAPIEN 3 Ultra (Ultra) and SAPIEN 3 (S3) transcatheter heart valves (THVs). BACKGROUND: The latest generation balloon-expandable Ultra THV incorporates new technical features and might improve outcomes following TAVR. METHODS: This registry included all consecutive patients who underwent TAVR with either the Ultra or S3 between January 2014 and January 2020. One-to-one propensity score matching was performed to account for differences in baseline characteristics. In-hospital and 30-day Valve Academic Research Consortium-2-defined outcomes were investigated. RESULTS: A total of 310 patients (n = 155 Ultra, n = 155 S3) were included. There were no significant differences in baseline characteristics after propensity score matching. Procedures were significantly more often performed under conscious sedation with Ultra compared with S3 (97.4% vs. 71.6%; p < 0.001). Pre-dilatation was more frequent with S3 compared with Ultra (85.2% vs. 42.6%; p < 0.001). In-hospital outcomes, including device success (91.6% vs. 95.5%; p = 0.165), major vascular complications (12.3% vs. 11.0%; p = 0.723), and new pacemaker implantation (5.8% vs. 4.5%; p = 0.608), were comparable between S3 and Ultra patients, respectively. Post-procedural mean transprosthetic gradients (13.2 ± 5.7 mm Hg vs. 13.1 ± 4.7 mm Hg; p = 0.829) and rate of moderate or greater paravalvular leakage (PVL) (1.3% vs. 2.7%; p = 0.414) were comparable, whereas mild PVL was more frequent with S3 compared with Ultra (43.0% vs. 18.7%; p < 0.001). CONCLUSIONS: Device success rates were high with both balloon-expandable THVs, with overall low rates of adverse events up to 30 days after TAVR. Despite a lower frequency of pre-dilatation, significant reduction of mild PVL confirms improved annular sealing properties of the novel Ultra THV.