Current State of the Art in Ventricle Tissue Engineering

State of the art in Purkinje bioengineering

This review article will cover the recent developments in the new evolving field of Purkinje bioengineering and the development of human Purkinje networks. Recent work has progressed to the point of a methodological and systematic process to bioengineer Purkinje networks. This involves the development of 3D models based on human anatomy, followed by the development of tunable biomaterials, and strategies to reprogram stem cells to Purkinje cells. Subsequently, the reprogrammed cells and the biomaterials are coupled to bioengineer Purkinje networks, which are then tested using a small animal injury model. In this article, we discuss this process as a whole and then each step separately. We then describe potential applications of bioengineered Purkinje networks and challenges in the field that need to be overcome to move this field forward. Although the field of Purkinje bioengineering is new and in a state of infancy, it holds tremendous potential, both for therapeutic applications and to develop tools that can be used for disease modeling.

Toxicity of low dose bisphenols in human iPSC-derived cardiomyocytes and human cardiac organoids - Impact on contractile function and hypertrophy

Bisphenol A (BPA) and its analogs are common environmental chemicals with various adverse health impacts, including cardiac toxicity. In this study, we examined the long term effect of low dose BPA and three common BPA analogs, bisphenol S (BPS), bisphenol F (BPF), and bisphenol AF (BPAF), in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) based models. HiPSC-CMs and human cardiac organoids were exposed to these chemicals for 4-5 or 20 days. 1 nM BPA, BPS, and BPAF, but not BPF, resulted in suppressed myocyte contractility, retarded contraction kinetics, and aberrant Ca2+ transients in hiPSC-CMs. In cardiac organoids, BPAF and BPA, but not the other bisphenols, resulted in suppressed contraction and Ca2+ transients, and aberrant contraction kinetics. The order of toxicities was BPAF > BPA>∼BPS > BPF and the toxicities of BPAF and BPA were more pronounced under longer exposure. The impact of BPAF on myocyte contraction and Ca2+ handling was mediated by reduction of sarcoplasmic reticulum Ca2+ load and inhibition of L-type Ca2+ channel involving alternation of Ca2+ handling proteins. Impaired myocyte Ca2+ handling plays a key role in cardiac pathophysiology and is a characteristic of cardiac hypertrophy; therefore we examined the potential pro-hypertrophic cardiotoxicity of these bisphenols. Four to five day exposure to BPAF did not cause hypertrophy in normal hiPSC-CMs, but significantly exacerbated the hypertrophic phenotype in myocytes with existing hypertrophy induced by endothelin-1, characterized by increased cell size and elevated expression of the hypertrophic marker proBNP. This pro-hypertrophic cardiotoxicity was also occurred in cardiac organoids, with BPAF having the strongest toxicity, followed by BPA. Our findings demonstrate that long term exposures to BPA and some of its analogs cause contractile dysfunction and abnormal Ca2+ handling, and have potential pro-hypertrophic cardiotoxicity in human heart cells/tissues, and suggest that some bisphenol chemicals may be a risk factor for cardiac hypertrophy in human hearts.

Recent advances in biological pumps as a building block for bioartificial hearts

The field of biological pumps is a subset of cardiac tissue engineering and focused on the development of tubular grafts that are designed generate intraluminal pressure. In the simplest embodiment, biological pumps are tubular grafts with contractile cardiomyocytes on the external surface. The rationale for biological pumps is a transition from planar 3D cardiac patches to functional biological pumps, on the way to complete bioartificial hearts. Biological pumps also have applications as a standalone device, for example, to support the Fontan circulation in pediatric patients. In recent years, there has been a lot of progress in the field of biological pumps, with innovative fabrication technologies. Examples include the use of cell sheet engineering, self-organized heart muscle, bioprinting and in vivo bio chambers for vascularization. Several materials have been tested for biological pumps and included resected aortic segments from rodents, type I collagen, and fibrin hydrogel, to name a few. Multiple bioreactors have been tested to condition biological pumps and replicate the complex in vivo environment during controlled in vitro culture. The purpose of this article is to provide an overview of the field of the biological pumps, outlining progress in the field over the past several years. In particular, different fabrication methods, biomaterial platforms for tubular grafts and examples of bioreactors will be presented. In addition, we present an overview of some of the challenges that need to be overcome for the field of biological pumps to move forward.

Engineering Models of the Heart Left Ventricle

Despite capturing the imagination of scientists for decades, the goal of creating an artificial heart for transplantation proved to be significantly more challenging than initially anticipated. Toward this goal, recent ground-breaking studies demonstrate the development of functional left ventricular (LV) models. LV models are artificially constructed 3D chambers that are capable of containing liquid within the engineered cavity and exhibit the functionality of native LV including contraction, ejection of fluid, and electrical impulse propagation. Various hydrogels and polymers have been used in manufacturing of LV models, relying on techniques such as electrospinning, bioprinting, casting, and molding. Most studies scaled down the models based on the dimensions of the human or rat ventricle. Initially, neonatal rat cardiomyocytes were the cell type of choice for construction the LV models. Yet, as the stem cell biology field advanced, recent studies focused on the use of cardiomyocytes derived from human induced pluripotent stem cells. In this review, we first describe the physiological characteristics of the human heart, to establish the parameter space for modeling. We then elaborate on current advances in the field and compare recently developed LV models among themselves and with the native human left ventricle. Fabrication methods, cell types, biomaterials, functional properties, and disease modeling capability are some of the major parameters that have distinguished these models. We also highlight some of the current challenges in this field, such as vascularization, cell composition and fidelity, and discuss potential solutions to overcome them.

3D Printing for Medical Applications: Current State of the Art and Perspectives during the COVID-19 Crisis

The coronavirus SARS-CoV-2 pandemic has affected over one hundred million people worldwide and has resulted in over two million deaths. In addition to the toll that coronavirus takes on the health of humans infected with the virus and the potential long term effects of infection, the repercussions of the pandemic on the economy as well as on the healthcare system have been enormous. The global supply of equipment necessary for dealing with the pandemic experienced extreme stress as healthcare systems around the world attempted to acquire personal protective equipment for their workers and medical devices for treating COVID-19. This review describes how 3D printing is currently being used in life saving surgeries such as heart and lung surgery and how 3D printing can address some of the worldwide shortage of personal protective equipment, by examining recent trends of the use of 3D printing and how these technologies can be applied during and after the pandemic. We review the use of 3D printed models for treating the long term effects of COVID-19. We then focus on methods for generating face shields and different types of respirators. We conclude with areas for future investigation and application of 3D printing technology.