This book presents a systematic overview of the technologies currently being explored and utilized in the fields of cardiovascular tissue engineering and regenerative medicine. Considering the unprecedented rapid progress occurring on multiple technological fronts in cardiac tissue engineering, this important new volume fills a need for an up-to-date, comprehensive text on emerging advanced biological and engineering tools. The book is an important resource for anyone looking to understand the emerging topics that have the potential to substantially influence the future of the field. Coverage includes iPS stem cell technologies, nanotechnologies and nanomedicine, advanced biomanufacturing, 3D culture systems, 3D organoid systems, genetic approaches to cardiovascular tissue engineering, and organ on a chip. This book will be a valuable guide for research scientists, students, and clinical researchers in the fields of cardiovascular biology, medicine, and bioengineering, as well as industry-based practitioners working in biomaterial science, nanomaterials and technology, and rapid prototyping and biomanufacturing (3D bioprinting).

Cardiac tissue engineering enables the generation of functional human cardiac tissue using cells in combination with biocompatible materials. Human pluripotent stem cell (hPSC)-derived cardiomyocytes provide a cell source for cardiac tissue engineering; however, their immaturity limits their potential applications. Here we sought to study the effect of mechanical conditioning and electrical pacing on the maturation of hPSC-derived cardiac tissues. In the first part of the study, cardiomyocytes derived from human induced pluripotent stem cells (hIPSCs) were used to generate collagen-based bioengineered human cardiac tissue. Engineered tissue constructs were subject to different stress and electrical pacing conditions. This engineered human myocardium exhibits Frank-Starling curve-type force-length relationships. After 2 weeks of static stress conditioning, the engineered myocardium demonstrated at least 10-fold increase in contractility and tensile stiffness, greater cell alignment, and a 1.5-fold increase in cell size and cell volume fraction within the constructs. Stress conditioning also increased sarco-endoplasmic reticulum calcium transport ATPase 2 (SERCA2) expression. When electrical pacing was combined with static stress conditioning, the tissues showed an additional 2-fold increase in force production, tensile stiffness, and contractility, with no change in cell alignment or cell size, suggesting maturation of excitation-contraction coupling. Supporting this notion, we found expression of RYR2 and SERCA2 further increased by combined static stress and electrical stimulation. These studies demonstrate that electrical pacing and mechanical stimulation promote both the structural and functional maturation of hiPSC-derived cardiac tissues. In the second part of the study, cardiovascular progenitor (CVP) cells derived from hPSC were used as the input cell population to generate engineered tissues. The effects of a 3-D microenvironment and mechanical stress on differentiation and maturation of human cardiovascular progenitors into myocardial tissue were evaluated. Compared to 2-D culture, the unstressed 3-D environment increased cardiomyocyte numbers and decreased smooth muscle numbers. Additionally, 3-D culture suppressed smooth muscle cell maturation. Mechanical stress conditioning further improved cardiomyocyte maturation. Cyclic stress-conditioning increased expression of several cardiac markers, like beta-myosin and cTnT, and the tissue showed enhanced force production. This 3-D system has facilitated understanding of the effect of mechanical stress on the differentiation and morphogenesis of distinct cardiovascular cell populations into organized, functional human cardiovascular tissues. In conclusion, we were able to create a complex engineered human cardiac tissue with both stem cell-derived cardiomyocytes and CVP cells. We showed that how environmental stimulations like mechanical stress, electrical pacing, and 3-D culturing can affect the maturation and specification of cells within the engineered cardiac tissues. The study paves our way to further apply these engineered cardiac tissues to other in vitro and in vivo usages like drug testing, clinical translation, and disease modeling.

This Volume of the series Cardiac and Vascular Biology offers a comprehensive and exciting, state-of-the-art work on the current options and potentials of cardiac regeneration and repair. Several techniques and approaches have been developed for heart failure repair: direct injection of cells, programming of scar tissue into functional myocardium, and tissue-engineered heart muscle support. The book introduces the rationale for these different approaches in cell-based heart regeneration and discusses the most important considerations for clinical translation. Expert authors discuss when, why, and how heart muscle can be salvaged. The book represents a valuable resource for stem cell researchers, cardiologists, bioengineers, and biomedical scientists studying cardiac function and regeneration.

This dissertation, "Facilitated Maturation of Cardiomyocytes Derived From Human Embryonic Stem Cells in 3D Collagen Matrix Upon Mesenchymal Cell Supplementation and Mechanical Stretch" by Wei, Alvin, Zhang, 張偉, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Cardiomyocytes derived from human embryonic stem cells (hESC-CMs) are regarded as promising cell source for regenerative medicine, drug testing and disease modeling. Nevertheless, these cardiomyocytes are immature in terms of contractile structure, metabolism and electrophysiological properties. There are increasing efforts using biological, chemical and physical approaches to facilitate maturation of hESC-CMs, with 3D matrix recognized as an optimal in vitro platform. In light of the previous findings, cardiac tissue strips were fabricated by encapsulating hESC-CMs into collagen/matrigel matrix in current study. The engineered tissue strips contract against mounted ends and grow into compact tissues with spontaneous beating. We hypothesize that addition of mesenchymal cells in small amount could accelerate maturation of hESC-CMs in collagen matrix, with mechanical stretch assumed to be superior to static stress in driving hESC-CM maturation. More specifically, we aim to demonstrate functional improvements of engineered cardiac tissue strips in terms of structural arrangement, mechanical properties, contractile performance and gene expression. Results showed that supplementation of mesenchymal cells at 3% could already boost maturation of fabricated heart tissue strips, where benefits of mesenchymal stem cell addition were shown to be comparable to that of fibroblast. Both cell types significantly promoted compaction and cell spreading to the same extent, with similar molecular signature in terms of gene expression and protein localization shown at tissue level. hMSC co-encapsulated tissues possess greater mechanical properties than hFB added counterparts such as elastic modulus, passive tension and twitch force under strain, yet the difference was not significant. Cyclic stretch was demonstrated to render better maturated engineered cardiac tissues when comparing with static stress, with static stretch showed similar advantages, albeit to a lesser extent. Both stretch schemes outperformed static stressed samples, as evidenced by more elongated sarcomere, stronger twitch force, steeper stress-strain curve, greater elastic modulus and better expression of major contractile and hypertrophic genes. However, statistical significance was achieved only between cyclic stretched tissue strips and static stressed group in most of the evaluation assays, suggesting superiority of the cyclic stretch in functionalizing engineered cardiac tissue. In vitro maturation of cardiomyocytes is a complex process, which could be achieved through combination of multiple approaches such as mechanical loading, electrical stimulation, niche cell addition and perfusion. This study proved that mesenchymal stem cells could be considered equivalent to fibroblasts in facilitating maturation of hESC-CMs within 3D collagen matrix. Moreover, mode of loading does affect functionality of engineered cardiac tissue, with cyclic stretch demonstrated to elicit greatest improvement. Findings of current study contribute to bioengineering of functional heart tissue from hESC-derived cardiomyocytes in the long run. DOI: 10.5353/th_b5689289 Subjects: Heart cells Embryonic stem cells

Medical research made huge strides in treating heart disease in the 20th century, from drug-eluding stents to automatic internal defibrillators. Public awareness of the dangers of heart disease has never been more pervasive. Now, though, ten years into a new millennium, scientists are gearing up for the next great challenges in tackling this pervasive condition. Cell therapy is going to be a key weapon in the fight against heart disease. It has the potential to address many cardiovascular conditions. From heart failure to atrioventricular nodal dysfunction, the young but promising field of cell therapy is set to play a significant role in developing the cures that the upcoming decades of hard work will yield. Regenerating the Heart: Stem Cells and the Cardiovascular System organizes the field into a digestible body of knowledge. Its four sections cover mechanical regeneration, electrical regeneration, cardiac tissues and in vivo stem cell therapies. An array of talented researchers share the fruits of their labors, with chapters covering such crucial issues as the cardiogenic potential of varying stem cell types, the ways in which they might be used to tackle arrhythmias, their possible application to biological replacements for cardiac tissues such as valves, and the varying approaches used in the in vivo evaluation of stem cell therapies, including methods of delivering stem cells to the myocardium. This comprehensive survey of an area of research with such exciting potential is an invaluable resource both for veteran stem cell researchers who need to monitor fresh developments, and for newly minted investigators seeking inspirational examples.