"Abnormal heart rhythms are a leading cause of mortality worldwide. Tachycardias, which are abnormally fast heart rhythms, can be caused by a circulating wave of excitation referred to as reentry. Patients who previously experienced a myocardial infarction are at a particularly high risk of developing re-entrant rhythms, as scarring can create the requisite pathway. Anatomical cardiac re-entry occurs when an impulse propagates in a circuit around an inexcitable obstacle instead of terminating at the base of the ventricles at the end of the cardiac cycle. In this thesis, I carried out experimental studies using novel techniques in tissue patterning to investigate plausible mechanisms of re-entry formation. The model system consists of a monolayer of human induced pluripotent stem cells differentiated into cardiomyocytes (hiPSCs) and sensitized to light by expression of Channelrhodopsin-2 (ChR2), a light activated channel. By incorporating CHR2, precise short pulses (100 ms) of patterned light could be applied to stimulate the monolayers. By applying long pulses (500 ms) of patterned light to the monolayer, conduction block could be provoked in the illuminated region. The light exposure parameters and patterns can be readily changed anytime during the experiment. These results demonstrate that an all optical dynamical approach is feasible to both stimulate and induce regions of block in the monolayer. This investigation provides a novel strategy for studying the mechanisms of arrhythmia generation in a model system that may lead to insights for treatment options"--

Cardiovascular disease (CVD) remains the leading cause of death in the United States with a range of treatments that vary according to the function that is comprised and patient-case severity. Despite progress in medicine and biomedical research, current cellular therapies are incapable of repairing and restoring cardiac function for heart-related CVDs that stem from dysfunctional cardiomyocytes (CM) or cell death. Since the human heart is incapable of regenerating itself naturally, a possible therapeutic strategy is to use human induced pluripotent stem cells (hiPSCs) to derive autologous CMs for replacing nonfunctioning or diseased cells. However, producing sufficient quantities of functionally suitable contractile and pacemaking CM subtypes poses a fundamental hurdle. Cellular interactions with the extracellular matrix (ECM) have been shown to transduce critical signals for cell-lineage specification. Previous studies that investigated the interactions between hiPSC-derived CMs and ECM proteins have shown that protein composition provides biochemical cues that are responsible for phenotypic maintenance and development. Additionally, prior studies that examined the interplay between human pluripotent stem cells (iPSC and ESC) and ECM elasticity have demonstrated defined substrate stiffness induces stem cell differentiation and lineage specification. In addition, these studies have indicated ECM stiffness provides biomechanical cues for CM functional maturation. HiPSC directed cardiogenesis protocols have improved since their inception, but generating pure and functionally mature populations of hiPSCderived CMs remains a prominent issue. Based on these findings, the ECM has a necessary presence that is absent in feeder-free hiPSC-derived CM cultures. The primary goal of the Lieu laboratory is to investigate the differentiation, enrichment and maturation of hiPSC-derived derived pacemaking and contractile CMs. As a way to contribute to this goal, we examined how the ECM influences CM subtype specification and phenotype maintenance by evaluating properties of the ECM independently to determine the mechanisms by which the ECM niche facilitates differentiation and CM lineage specification into pacemaking and contractile subtypes. We hypothesized that the biochemical and biomechanical properties of the ECM could promote CM subtype specification and facilitate individual functional phenotype maintenance. Our study was organized in two specific aims. The first aim was to determine the reprogramming effects of the ECM microenvironment on hiPSC-derived CM subtype plasticity by performing immunocytochemical (ICC) staining of hiPSC-derived CM markers to quantify protein expression and optical recording of hiPSC-derived action potentials in vitro. The second aim was to determine the effects of the ECM on hiPSC-derived cardiac progenitor cell (CPC) differentiation into contractile and pacemaking CM subtypes by performing immunocytochemical (ICC) staining of hiPSC-derived CM markers in vitro to quantify protein expression. Here, we demonstrated that the expression of pacemaking, contractile, and integrin-binding markers were dependent on different variables of the ECM during hiPSC-derived CM reprogramming and hiPSC-derived CPC differentiation. Furthermore, the electrophysiological properties and subtype distribution of hiPSC- derived CMs were dependent on the unique combination of ECM protein coating and elasticity of the ECM.

This volume covers all aspects of embryonic stem cell differentiation, including mouse embryonic stem cells, mouse embryonic germ cells, monkey and human embryonic stem cells, and gene discovery.* Early commitment steps and generation of chimeric mice* Differentiation to mesoderm derivatives* Gene discovery by manipulation of mouse embryonic stem cells

Defined as, “The science about the development of an embryo from the fertilization of the ovum to the fetus stage,” embryology has been a mainstay at universities throughout the world for many years. Throughout the last century, embryology became overshadowed by experimental-based genetics and cell biology, transforming the field into developmental biology, which replaced embryology in Biology departments in many universities. Major contributions in this young century in the fields of molecular biology, biochemistry and genomics were integrated with both embryology and developmental biology to provide an understanding of the molecular portrait of a “development cell.” That new integrated approach is known as stem-cell biology; it is an understanding of the embryology and development together at the molecular level using engineering, imaging and cell culture principles, and it is at the heart of this seminal book. Stem Cells and Regenerative Medicine: From Molecular Embryology to Tissue Engineering is completely devoted to the basic developmental, cellular and molecular biological aspects of stem cells as well as their clinical applications in tissue engineering and regenerative medicine. It focuses on the basic biology of embryonic and cancer cells plus their key involvement in self-renewal, muscle repair, epigenetic processes, and therapeutic applications. In addition, it covers other key relevant topics such as nuclear reprogramming induced pluripotency and stem cell culture techniques using novel biomaterials. A thorough introduction to stem-cell biology, this reference is aimed at graduate students, post-docs, and professors as well as executives and scientists in biotech and pharmaceutical companies.

Stem Cells in Clinical Practice and Tissue Engineering is a concise book on applied methods of stem cell differentiation and optimization using tissue engineering methods. These methods offer immediate use in clinical regenerative medicine. The present volume will serve the purpose of applied stem cell differentiation optimization methods in clinical research projects, as well as be useful to relatively experienced stem cell scientists and clinicians who might wish to develop their stem cell clinical centers or research labs further. Chapters are arranged in the order of basic concepts of stem cell differentiation, clinical applications of pluripotent stem cells in skin, cardiac, bone, dental, obesity centers, followed by tissue engineering, new materials used, and overall evaluation with their permitted legal status.

Mesenchymal stem cell-derived exosomes are at the forefront of research in two of the most high profile and funded scientific areas – cardiovascular research and stem cells. Mesenchymal Stem Cell Derived Exosomes provides insight into the biofunction and molecular mechanisms, practical tools for research, and a look toward the clinical applications of this exciting phenomenon which is emerging as an effective diagnostic. Primarily focused on the cardiovascular applications where there have been the greatest advancements toward the clinic, this is the first compendium for clinical and biomedical researchers who are interested in integrating MSC-derived exosomes as a diagnostic and therapeutic tool. - Introduces the MSC-exosome mediated cell-cell communication - Covers the major functional benefits in current MSC-derived exosome studies - Discusses strategies for the use of MSC-derived exosomes in cardiovascular therapies