The endothelium lines the inner surface of all blood vessels representing an important tissue with vital functions to mediate tissue homeostasis. Tissue-tissue interfaces play a critical role throughout the human body where endothelial cells (ECs) contribute by creating vital barriers with tight and adherens junctions to regulate permeability of macromolecules and fluids while protecting and nourishing adjacent tissue. They are the most prominent cell type to experience physical forces of shear, stretch and strain through the laminar pulsatile nature of the bloodstream. Alterations in physiological flow profiles have a strong impact on EC pathology contributing to diseases like atherosclerosis and coronary heart disease as well as inflammatory conditions. Further, they are among the first cell types to interact with xenobiotics. Endothelial endocytosis and barrier regulation have profound impact on drug-tissue interactions. There is the need for technological innovations and improvements to study EC biology, EC-epithelial and EC-nanocarrier interactions in more complex settings that take physiological biophysical and biochemical cues into account. For this purpose, the Multi-Organ-Tissue-Flow (MOTiF) biochip has been invented and its design has been finalised during the beginning of this thesis. The objective was to develop handling and cellular seeding protocols for the biochip to establish more in vivo-like and more complex in vitro EC culture approaches. Within the scope of this thesis, the biochip has been characterised for perfused EC culture. Complex co-cultures with tissue resident macrophages and further with murine cortical spheroids present in liver sinusoidal structures and at the blood-brain barrier (BBB) have been established, respectively. Additionally, first applications under physiological parameters of shear stress have been made. The focus was on nanocarrier uptake profiles and microvascular endothelial barrier interaction.

Techniques for microfabricating intricate microfluidic structures that mimic the microenvironment of tissues and organs, combined with the development of biomaterials with carefully engineered surface properties, have enabled new paradigms in and cell culture-based models for human diseases. The dimensions of surface features and fluidic channels made accessible by these techniques are well-suited to the size scale of biological cells. Microfluidic Cell Culture Systems applies design and experimental techniques used in in microfluidics, and cell culture technologies to organ-on-chip systems. This book is intended to serve as a professional reference, providing a practical guide to design and fabrication of microfluidic systems and biomaterials for use in cell culture systems and human organ models. The book covers topics ranging from academic first principles of microfluidic design, to clinical translation strategies for cell culture protocols. The goal is to help professionals coming from an engineering background to adapt their expertise for use in cell culture and organ models applications, and likewise to help biologists to design and employ microfluidic technologies in their cell culture systems. This 2nd edition contains new material that strengthens the focus on in vitro models useful for drug discovery and development. One new chapter reviews liver organ models from an industry perspective, while others cover new technologies for scaling these models and for multi-organ systems. Other new chapters highlight the development of organ models and systems for specific applications in disease modeling and drug safety. Previous chapters have been revised to reflect the latest advances. Provides design and operation methodology for microfluidic and microfabricated materials and devices for organ-on-chip disease and safety models. This is a rapidly expanding field that will continue to grow along with advances in cell biology and microfluidics technologies. Comprehensively covers strategies and techniques ranging from academic first principles to industrial scale-up approaches. Readers will gain insight into cell-material interactions, microfluidic flow, and design principles. Offers three fundamental types of information: 1) design principles, 2) operation techniques, and 3) background information/perspectives. The book is carefully designed to strike a balance between these three areas, so it will be of use to a broad range of readers with different technical interests and educational levels.

Flow-induced parallel alignment of endothelial cells (ECs) is replicated in vitro in macroscale parallel plate flow chambers (PPFCs), but with increasing application of microfluidic platforms to study EC biology and model ECs in organ-on-a-chip platforms, there is a need to better understand flow regulation of ECs in microscale platforms. Previous work in our labs found that EC monolayers confined in microchannels and PDMS stencils aligned perpendicular to the direction of flow in contrast to parallel alignment in macroscale PPFCs. The goal of this thesis was to elucidate the microfluidic culture parameters that condition for the confined EC phenotype. Perpendicular alignment to flow was observed in human umbilical vein ECs (HUVECs) across all tested physical and geometrical conditions and suggested that spatial control provides cues for a confined EC phenotype. This work demonstrated that perpendicular alignment to flow is a robust response in microscale-cultured ECs.

Microphysiological systems, also known as organ-on-a-chip systems, possess significant potential as organotypic models of human tissues, including vascular tissue interfaces that are ubiquitous throughout the human body. As microfluidic systems, organs-on-chips also possess significant untapped analytical potential. Cellular analysis in organs-on-chips, however, currently relies on standard methods designed for traditional in vitro cell culture vessels like microtiter plates. These methods disturb the cell culture environment, rely on multiple manual steps and are not designed to operate in small microfluidic volumes. The aim of this thesis was to design and develop online cellular analysis methods that are suitable for integration into the organotypic microenvironment of microvessel-on-a-chip models. Cellular analysis methods for cell secretion and barrier function monitoring were specifically considered. For integrated cell secretion monitoring, a numerical study correlated physiological shear flow to biosensor reaction kinetics in a microfluidic vascular model with online biosensing. Three critical parameters (critical shear stress, Peclet and Biot numbers) in conjunction with the numerical analysis enabled the minimization of biosensor response times while preserving physiological shear flows. For integrated barrier function monitoring, endothelial permeability was measured online in a Transwell-based microfluidic vascular model using a novel electrochemical permeability assay. Unlike the standard fluorescence-based permeability assay, this enabled endothelial permeability to be measured directly on-chip inside an incubator without the need for manual sampling, or bulky and costly optical instrumentation. Finally, the electrochemical permeability assay was implemented in a hydrogel-based microfluidic vascular model with gel-embedded electrodes. Online endothelial permeability measurements were performed in a 3D culture environment, demonstrating the ability of the assay to operate in the low volume organotypic microenvironments characteristic of microphysiological systems. The miniaturized electrochemical format is furthermore suitable for parallelization and higher throughput analysis. In summary, the integration of cellular analysis methods is critical to fulfilling the tremendous promise of microphysiological systems. The capability to perform multiparametric online analysis at the cellular level has the potential to set these systems apart from current models of the human organism.

Nanobiomaterials in Soft Tissue Engineering brings together recent developments and the latest approaches in the field of soft tissue engineering at the nanoscale, offering a new perspective on the evolution of current and future applications. Leading researchers from around the world present the latest research and share new insights. This book covers the major conventional and unconventional fabrication methods of typical three-dimensional scaffolds used in regenerative medicine. Surface modification and spatial properties are included in an up-to-date overview, with the latest in vivo applications of engineered 3D scaffolds discussed. The book also considers the impact, advantages and future scope of the various methods. This book will be of interest to postdoctoral researchers, professors and students engaged in the fields of materials science, biotechnology and applied chemistry. It will also be highly valuable to those working in industry, including pharmaceutics and biotechnology companies, medical researchers, biomedical engineers and advanced clinicians. An informative handbook for researchers, practitioners and students working in biomedical, biotechnological and engineering fields. A detailed and invaluable overview of soft tissue engineering, including the most recent scientific developments. Proposes novel opportunities and ideas for developing or improving technologies in nanomedicine and nanobiology.

Tissue Engineering: Current Status and Challenges bridges the gap between biomedical scientists and clinical practitioners. The work reviews the history of tissue engineering, covers the basics required for the beginner, and inspires those in the field toward future research and application emerging in this fast-moving field. Written by global experts in the field for those studying and researching tissue engineering, the book reviews regenerative technologies, stem cell research and regeneration of organs. It then moves to soft tissue engineering (heart, vascular, muscle and 3D scaffolding and printing), hard tissue engineering (bone, dental myocardial and musculoskeletal) and translational avenues in the field. Introduces readers to the history and benefits of tissue engineering Includes coverage of new techniques and technologies, such as nanotechnology and nanoengineering Presents concepts, ideology and theories which form the foundation for next-generation tissue engineering

Summarizing the latest trends and the current state of this research field, this up-to-date book discusses in detail techniques to perform localized alterations on surfaces with great flexibility, including microfluidic probes, multifunctional nanopipettes and various surface patterning techniques, such as dip pen nanolithography. These techniques are also put in perspective in terms of applications and how they can be transformative of numerous (bio)chemical processes involving surfaces. The editors are from IBM Zurich, the pioneers and pacesetters in the field at the forefront of research in this new and rapidly expanding area.