The Real Need for Regenerative Medicine in the Future of Congenital Heart Disease Treatment

Long-term outcomes of functional single ventricles associated with heterotaxy syndrome†

OBJECTIVES

The goal of this study was to determine the long-term surgical outcomes of patients with functional single ventricles associated with heterotaxy syndrome, risk factors for mortality and factors associated with Fontan stage completion.

METHODS

Overall, 279 patients with a functional single ventricle associated with heterotaxy syndrome who underwent an initial surgical procedure at our institute between 1978 and 2021 were grouped into 4 "eras" based on the surgical year during which the initial procedure was performed: era 1 (1978-1989, n = 71), era 2 (1990-1999, n = 98), era 3 (2000-2009, n = 64) and era 4 (2010-2021, n = 46). Neonatal surgery was more frequent in eras 3 and 4 than in eras 1 and 2.

RESULTS

Overall, 228 patients had right atrial isomerism; 120 patients (43.0%) had a total anomalous pulmonary venous connection; and 58 patients (20.8%) underwent an initial procedure as neonates. Overall survival rates at 10, 20 and 30 years after the initial procedure were 47.1%, 40.6% and 36.1%, respectively. Neonatal surgery (P < 0.001), total anomalous pulmonary venous connection repair at the initial procedure (P < 0.001) and early era (P < 0.001) were identified as risk factors for mortality, with the last 2 variables being negatively associated with Fontan stage completion (P < 0.001 for both).

CONCLUSIONS

Although era had a favourable effect on survival, total anomalous pulmonary venous connection with intrinsic pulmonary vein obstruction was associated with both mortality and Fontan stage completion.

CLINICAL REGISTRATION NUMBER

R19092.

Cardiac tissue engineering for the treatment of hypoplastic left heart syndrome (HLHS)

Hypoplastic left heart syndrome (HLHS) is a deadly congenital heart disease that arises when the left ventricle and outflow tract fail to develop appropriately, inhibiting the adequate perfusion of the rest of the body. Historically, this disease has been treated via a series of surgeries that allows the heart to use a single ventricle. These surgeries are often a palliative measure, and heart transplantation is the only definitive therapy that exists for this condition. It has been hypothesized that stem cell-based regenerative therapies could have a role in promoting cardiac tissue regeneration in HLHS patients who are undergoing palliative surgery. Several clinical trials have demonstrated that introducing pluripotent cells into the heart is safe, feasible, and capable of improving right ventricular ejection fraction (RVEF). However, while these approaches show great promise, there is still room for development. There is a substantial body of pre-clinical work that is focused on generating increasingly large and complex pieces of cardiac tissue in the form of cardiac patches, with the idea that these could be used to rebuild and strengthen the heart in a robust and long-lasting manner. In total, stem cell-based therapies have much to offer when it comes to improving the treatment of HLHS.

Controlled and Synchronised Vascular Regeneration upon the Implantation of Iloprost- and Cationic Amphiphilic Drugs-Conjugated Tissue-Engineered Vascular Grafts into the Ovine Carotid Artery: A Proteomics-Empowered Study

Implementation of small-diameter tissue-engineered vascular grafts (TEVGs) into clinical practice is still delayed due to the frequent complications, including thrombosis, aneurysms, neointimal hyperplasia, calcification, atherosclerosis, and infection. Here, we conjugated a vasodilator/platelet inhibitor, iloprost, and an antimicrobial cationic amphiphilic drug, 1,5-bis-(4-tetradecyl-1,4-diazoniabicyclo [2.2.2]octan-1-yl) pentane tetrabromide, to the luminal surface of electrospun poly(ε-caprolactone) (PCL) TEVGs for preventing thrombosis and infection, additionally enveloped such TEVGs into the PCL sheath to preclude aneurysms, and implanted PCL^Ilo/CAD TEVGs into the ovine carotid artery (n = 12) for 6 months. The primary patency was 50% (6/12 animals). TEVGs were completely replaced with the vascular tissue, free from aneurysms, calcification, atherosclerosis and infection, completely endothelialised, and had clearly distinguishable medial and adventitial layers. Comparative proteomic profiling of TEVGs and contralateral carotid arteries found that TEVGs lacked contractile vascular smooth muscle cell markers, basement membrane components, and proteins mediating antioxidant defense, concurrently showing the protein signatures of upregulated protein synthesis, folding and assembly, enhanced energy metabolism, and macrophage-driven inflammation. Collectively, these results suggested a synchronised replacement of PCL with a newly formed vascular tissue but insufficient compliance of PCL^Ilo/CAD TEVGs, demanding their testing in the muscular artery position or stimulation of vascular smooth muscle cell specification after the implantation.

Natural Polymers in Heart Valve Tissue Engineering: Strategies, Advances and Challenges

In the history of biomedicine and biomedical devices, heart valve manufacturing techniques have undergone a spectacular evolution. However, important limitations in the development and use of these devices are known and heart valve tissue engineering has proven to be the solution to the problems faced by mechanical and prosthetic valves. The new generation of heart valves developed by tissue engineering has the ability to repair, reshape and regenerate cardiac tissue. Achieving a sustainable and functional tissue-engineered heart valve (TEHV) requires deep understanding of the complex interactions that occur among valve cells, the extracellular matrix (ECM) and the mechanical environment. Starting from this idea, the review presents a comprehensive overview related not only to the structural components of the heart valve, such as cells sources, potential materials and scaffolds fabrication, but also to the advances in the development of heart valve replacements. The focus of the review is on the recent achievements concerning the utilization of natural polymers (polysaccharides and proteins) in TEHV; thus, their extensive presentation is provided. In addition, the technological progresses in heart valve tissue engineering (HVTE) are shown, with several inherent challenges and limitations. The available strategies to design, validate and remodel heart valves are discussed in depth by a comparative analysis of in vitro, in vivo (pre-clinical models) and in situ (clinical translation) tissue engineering studies.

Heparin-Eluting Tissue-Engineered Bioabsorbable Vascular Grafts

The creation of small-diameter tissue-engineered vascular grafts using biodegradable materials has the potential to change the quality of cardiovascular surgery in the future. The implantation of these tissue-engineered arterial grafts has yet to reach clinical application. One of the reasons for this is thrombus occlusion of the graft in the acute phase. In this paper, we first describe the causes of accelerated thrombus formation and discuss the drugs that are thought to inhibit thrombus formation. We then review the latest research on methods to locally bind the anticoagulant heparin to biodegradable materials and methods to extend the duration of sustained heparin release. We also discuss the results of studies using large animal models and the challenges that need to be overcome for future clinical applications.