Gene transfer to promote cardiac regeneration

Fulfilling the Promise of RNA Therapies for Cardiac Repair and Regeneration

The progressive appreciation that multiple types of RNAs regulate virtually all aspects of tissue function and the availability of effective tools to deliver RNAs in vivo now offers unprecedented possibilities for obtaining RNA-based therapeutics. For the heart, RNA therapies can be developed that stimulate endogenous repair after cardiac damage. Applications in this area include acute cardioprotection after ischemia or cancer chemotherapy, therapeutic angiogenesis to promote new blood vessel formation, regeneration to form new cardiac mass, and editing of mutations to cure inherited cardiac disease. While the potential of RNA therapeutics for all these conditions is exciting, the field is still in its infancy. A number of roadblocks need to be overcome for RNA therapies to become effective, in particular, related to the problem of delivering RNA medicines into the cells and targeting them specifically to the heart.

A Bibliometric and Visualized Analysis of Cardiac Regeneration Over a 20-Year Period

Background: Recent research has suggested that cardiac regeneration may have the widely applicable potential of treating heart failure (HF). A comprehensive understanding of the development status of this field is conducive to its development. However, no bibliometric analysis has summarized this field properly. We aimed to analyze cardiac regeneration-related literature over 20 years and provide valuable insights.

Methods: Publications were collected from the Web of Science Core Collection (WoSCC). Microsoft Excel, VOSviewer, CiteSpace, and alluvial generator were used to analyze and present the data.

Results: The collected 11,700 publications showed an annually increasing trend. The United States and Harvard University were the leading force among all the countries and institutions. The majority of articles were published in Circulation Research, and Circulation was the most co-cited journal. According to co-citation analysis, burst detection and alluvial flow map, cardiomyocyte proliferation, stem cells, such as first-and second-generation, extracellular vesicles especially exosomes, direct cardiac reprogramming, macrophages, microRNAs, and inflammation have become more and more popular recently.

Conclusions: Cardiac regeneration remains a research hotspot and develops rapidly. How to modify cardiac regeneration endogenously and exogenously may still be the hotspot in the future and should be discussed more deeply.

Gene Therapy for the Heart Lessons Learned and Future Perspectives

While clinical gene therapy celebrates its first successes, with several products already approved for clinical use and several hundreds in the final stages of the clinical approval pipeline, there is not a single gene therapy approach that has worked for the heart. Here, we review the past experience gained in the several cardiac gene therapy clinical trials that had the goal of inducing therapeutic angiogenesis in the ischemic heart and in the attempts at modulating cardiac function in heart failure. Critical assessment of the results so far achieved indicates that the efficiency of cardiac gene delivery remains a major hurdle preventing success but also that improvements need to be sought in establishing more reliable large animal models, choosing more effective therapeutic genes, better designing clinical trials, and more deeply understanding cardiac biology. We also emphasize a few areas of cardiac gene therapy development that hold great promise for the future. In particular, the transition from gene addition studies using protein-coding cDNAs to the modulation of gene expression using small RNA therapeutics and the improvement of precise gene editing now pave the way to applications such as cardiac regeneration after myocardial infarction and gene correction for inherited cardiomyopathies that were unapproachable until a decade ago.

Targeting the Cardiomyocyte Cell Cycle for Heart Regeneration

Adult mammalian cardiomyocytes (CMs) exhibit limited proliferative capacity, as cell cycle activity leads to an increase in DNA content, but mitosis and cytokinesis are infrequent. This makes the heart highly inefficient in replacing with neoformed cardiomyocytes lost contractile cells as occurs in diseases such as myocardial infarction and dilated cardiomyopathy. Regenerative therapies based on the implant of stem cells of diverse origin do not warrant engraftment and electromechanical connection of the new cells with the resident ones, a fundamental condition to restore the physiology of the cardiac syncytium. Consequently, there is a growing interest in identifying factors playing relevant roles in the regulation of the CM cell cycle to be targeted in order to induce the resident cardiomyocytes to divide into daughter cells and thus achieve myocardial regeneration with preservation of physiologic syncytial performance.

The adaptive immune response to cardiac injury-the true roadblock to effective regenerative therapies?

The regenerative capacity of adult human tissues and organs is limited, but recent developments have seen the advent of promising new technologies for regenerative therapy. The human heart is of particular interest for regenerative medicine, as cardiac tissue damage is repaired by the formation of rigid scar tissue, which causes inevitable structural changes and progressive functional decline leading to heart failure. Cardiac regenerative medicine aims to prevent scar formation or replace existing scars to halt or reverse adverse remodeling and therapeutic approaches include the use of biomaterials, gene therapies, delivery of growth factors, and (stem) cell therapies. Regenerative therapies, however, face significant obstacles in a hostile microenvironment. While the early immune response to a myocardial infarct is essential to ensure tissue integrity and to avoid fatal cardiac rupture, excessive activation of endogenous repair mechanisms may lead to ongoing inflammation, fibrosis, and sustained autoimmune-mediated tissue damage. Anti-cardiac autoreactivity of the adaptive immune system has been suggested to be involved in structural remodeling, functional decline, and the development of heart failure. It is, therefore, crucial to first understand the endogenous response to cardiac tissue damage and how to restore immune tolerance to cardiac tissue, before additional regenerative therapies can achieve their full potential.