Optimization of Enzymatic and Chemical Decellularization of Native Porcine Heart Valves for the Generation of Decellularized Xenografts.

One of the most important medical interventions for individuals with heart valvular disease is heart valve replacement, which is not without substantial challenges, particularly for pediatric patients. Due to their biological properties and biocompatibility, natural tissue-originated scaffolds derived from human or animal sources are one type of scaffold that is widely used in tissue engineering. However, they are known for their high potential for immunogenicity. Being free of cells and genetic material, decellularized xenografts, consequently, have low immunogenicity and, thus, are expected to be tolerated by the recipient's immune system. The scaffold ultrastructure and ECM composition can be affected by cell removal agents. Therefore, applying an appropriate method that preserves intact the structure of the ECM plays a critical role in the final result. So far, there has not been an effective decellularization technique that preserves the integrity of the heart valve's ultrastructure while securing the least amount of genetic material left. This study demonstrates a new protocol with untraceable cells and residual DNA, thereby maximally reducing any chance of immunogenicity. The mechanical and biochemical properties of the ECM resemble those of native heart valves. Results from this study strongly indicate that different critical factors, such as ionic detergent omission, the substitution of Triton X-100 with Tergitol, and using a lower concentration of trypsin and a higher concentration of DNase and RNase, play a significant role in maintaining intact the ultrastructure and function of the ECM.

Tricuspid Regurgitation and TAVR: Outcomes, Risk Factors and Biomarkers.

Background. The significance of concomitant tricuspid regurgitation (TR) in the context of transcatheter aortic valve replacement (TAVR) remains unclear. This study aimed to analyze the severity of TR before and after TAVR with regard to short- and long-term survival and to analyze the influencing factors. Methods. In our retrospective analysis, TR before and after TAVR was examined and patients were classified into groups accordingly. Special attention was paid to patients with post-interventional changes in TR. Mortality after TAVR was considered the primary endpoint of the analysis and major complications according to the Valve Academic Research Consortium 3 (VARC3) were compared. Moreover, biomarkers and risk factors for worsening or improvement of TR through TAVR were analyzed. Results. Among 775 patients who underwent TAVR in our center between January 2009 and December 2019, 686 patients (89%) featured low- and 89 patients (11%) high-grade TR. High-grade pre-TAVR TR was associated with worse short- (30-day), mid- (2-year) and long-term survival up to 8 years. Even though in nearly half of the patients with high-grade TR the regurgitation improved within seven days after TAVR (n = 42/89), this did not result in a survival benefit for this subgroup. On the other hand, a worsening of low-grade TR was seen in more than 10% of the patients (n = 73/686), which was also associated with a worse prognosis. Predictors of worsening of TR after TAVR were adipositas, impaired right ventricular function and the presence of mild TR. Age, atrial fibrillation, COPD, impaired renal function and elevated cardiac biomarkers were risk factors for mortality after TAVR independent from the grade of TR. Conclusions. Not only pre-interventional, but also post-TAVR high-grade TR is associated with a worse prognosis after TAVR. TAVR can change concomitant tricuspid regurgitation, but improvement does not have any impact on short- and long-term survival. Worsening of TR after TAVR is possible and impairs the prognosis.

Producing and Testing Prototype Tissue-Engineered 3D Tri-Leaflet Valved Stents on Biodegradable Poly-ε-Caprolactone Scaffolds.

Transcatheter pulmonary valve replacement is a minimally-invasive alternative treatment for right ventricular outflow tract dysfunction and has been rapidly evolving over the past years. Heart valve prostheses currently available still have major limitations. Therefore, one of the significant challenges for the future is the roll out of transcatheter tissue engineered pulmonary valve replacement to more patients. In the present study, biodegradable poly-ε-caprolactone (PCL) nanofiber scaffolds in the form of a 3D leaflet matrix were successfully seeded with human endothelial colony-forming cells (ECFCs), human induced pluripotent stem cell-derived MSCs (hMSCs), and porcine MSCs (pMSCs) for three weeks for the generation of 3D tissue-engineered tri-leaflet valved stent grafts. The cell adhesion, proliferation, and distribution of these 3D heart leaflets was analyzed using fluorescence microscopy and scanning electron microscopy (SEM). All cell lineages were able to increase the overgrown leaflet area within the three-week timeframe. While hMSCs showed a consistent growth rate over the course of three weeks, ECFSs showed almost no increase between days 7 and 14 until a growth spurt appeared between days 14 and 21. More than 90% of heart valve leaflets were covered with cells after the full three-week culturing cycle in nearly all leaflet areas, regardless of which cell type was used. This study shows that seeded biodegradable PCL nanofiber scaffolds incorporated in nitinol or biodegradable stents will offer a new therapeutic option in the future.

Transcatheter Aortic Valve Implantation by Intercostal Access: Initial Experience with a No-Touch Technique.

BACKGROUND: Transcatheter aortic valve implantation (TAVI) is now a well-established therapeutic option in an elderly high-risk patient cohort with aortic valve disease. Although most commonly performed via a transfemoral route, alternative approaches for TAVI are constantly being improved. Instead of the classical mini-sternotomy, it is possible to achieve a transaortic access via a right anterior mini-thoracotomy in the second intercostal space. We describe our experience with this sternum- and rib-sparing technique in comparison to the classical transaortic approach. METHODS: Our retrospective study includes 173 patients who were treated in our institution between January 2017 and April 2020 with transaortic TAVI via either upper mini-sternotomy or intercostal thoracotomy. The primary endpoint was 30-day mortality, and secondary endpoints were defined as major postoperative complications that included admission to the intensive care unit and overall hospital stay, according to the Valve Academic Research Consortium 3. RESULTS: Eighty-two patients were treated with TAo-TAVI by upper mini-sternotomy, while 91 patients received the intercostal approach. Both groups were comparable in age (mean age: 82 years) and in the proportion of female patients. The intercostal group had a higher rate of peripheral artery disease (41% vs. 22%, p = 0.008) and coronary artery disease (71% vs. 40%, p < 0.001) with a history of percutaneous coronary intervention or coronary artery bypass grafting, resulting in significantly higher preinterventional risk evaluation (EuroScore II 8% in the intercostal vs. 4% in the TAo group, p = 0.005). Successful device implantation and a reduction of the transvalvular gradient were achieved in all cases with a significantly lower rate of trace to mild paravalvular leakage in the intercostal group (12% vs. 33%, p < 0.001). The intercostal group required significantly fewer blood transfusions (0 vs. 2 units, p = 0.001) and tended to require less reoperation (7% vs. 15%, p = 0.084). Hospital stays (9 vs. 12 d, p = 0.011) were also shorter in the intercostal group. Short- and long-term survival in the follow-up showed comparable results between the two approaches (30-day, 6-month- and 2-year mortality: 7%, 23% and 36% in the intercostal vs. 9%, 26% and 33% in the TAo group) with acute kidney injury (AKI) and reintubation being independent risk factors for mortality. CONCLUSIONS: Transaortic TAVI via an intercostal access offers a safe and effective treatment of aortic valve stenosis.