Modelling Human Physiology on-Chip: Historical Perspectives and Future Directions

Basic models to advanced systems: harnessing the power of organoids-based microphysiological models of the human brain

Understanding the complexities of the human brain's function in health and disease is a formidable challenge in neuroscience. While traditional models like animals offer valuable insights, they often fall short in accurately mirroring human biology and drug responses. Moreover, recent legislation has underscored the need for more predictive models that more accurately represent human physiology. To address this requirement, human-derived cell cultures have emerged as a crucial alternative for biomedical research. However, traditional static cell culture models lack the dynamic tissue microenvironment that governs human tissue function. Advancedin vitrosystems, such as organoids and microphysiological systems (MPSs), bridge this gap by offering more accurate representations of human biology. Organoids, which are three-dimensional miniaturized organ-like structures derived from stem cells, exhibit physiological responses akin to native tissues, but lack essential tissue-specific components such as functional vascular structures and immune cells. Recent endeavors have focused on incorporating endothelial cells and immune cells into organoids to enhance vascularization, maturation, and disease modeling. MPS, including organ-on-chip technologies, integrate diverse cell types and vascularization under dynamic culture conditions, revolutionizing brain research by bridging the gap betweenin vitroandin vivomodels. In this review, we delve into the evolution of MPS, with a particular focus on highlighting the significance of vascularization in enhancing the viability, functionality, and disease modeling potential of organoids. By examining the interplay of vasculature and neuronal cells within organoids, we can uncover novel therapeutic targets and gain valuable insights into disease mechanisms, offering the promise of significant advancements in neuroscience and improved patient outcomes.

Understanding conceptus-maternal interactions: what tools do we need to develop?

Communication between the maternal endometrium and developing embryo/conceptus is critical to support successful pregnancy to term. Studying the peri-implantation period of pregnancy is critical as this is when most pregnancy loss occurs in cattle. Our current understanding of these interactions is limited, due to the lack of appropriate in vitro models to assess these interactions. The endometrium is a complex and heterogeneous tissue that is regulated in a transcriptional and translational manner throughout the oestrous cycle. While there are in vitro models to study endometrial function, they are static and 2D in nature or explant models and are limited in how well they recapitulate the in vivo endometrium. Recent developments in organoid systems, microfluidic approaches, extracellular matrix biology, and in silico approaches provide a new opportunity to develop in vitro systems that better model the in vivo scenario. This will allow us to investigate in a more high-throughput manner the fundamental molecular interactions that are required for successful pregnancy in cattle.

Tailoring biomaterials for biomimetic organs-on-chips

Organs-on-chips are microengineered microfluidic living cell culture devices with continuously perfused chambers penetrating to cells. By mimicking the biological features of the multicellular constructions, interactions among organs, vascular perfusion, physicochemical microenvironments, and so on, these devices are imparted with some key pathophysiological function levels of living organs that are difficult to be achieved in conventional 2D or 3D culture systems. In this technology, biomaterials are extremely important because they affect the microstructures and functionalities of the organ cells and the development of the organs-on-chip functions. Thus, herein, we provide an overview on the advances of biomaterials for the construction of organs-on-chips. After introducing the general components, structures, and fabrication techniques of the biomaterials, we focus on the studies of the functions and applications of these biomaterials in the organs-on-chips systems. Applications of the biomaterial-based organs-on-chips as alternative animal models for pharmaceutical, chemical, and environmental tests are described and highlighted. The prospects for exciting future directions and the challenges of biomaterials for realizing the further functionalization of organs-on-chips are also presented.

Sentinel supervised lung-on-a-chip: A new environmental toxicology platform for nanoplastic-induced lung injury

Nanoplastics are prevalent in the air and can be easily inhaled, posing a threat to respiratory health. However, there have been few studies investigating the impact of nanoplastics on lung injury, especially chronic obstructive pulmonary disease (COPD). Furthermore, cell and animal models cannot deeply understand the pollutant-induced COPD. Existing lung-on-a-chip models also lack interactions among immune cells, which are crucial in monitoring complex responses. In the study, we built the lung-on-a-chip to accurately recapitulate the structural features and key functions of the alveolar-blood barrier while integrating multiple immune cells. The stability and reliability of the lung-on-a-chip model were demonstrated by toxicological application of various environmental pollutants. We Further focused on exploring the association between COPD and polystyrene nanoplastics (PS-NPs). As a result, the cell viability significantly decreased as the concentration of PS-NPs increased, while TEER levels decreased and permeability increased. Additionally, PS-NPs could induce oxidative stress and inflammatory responses at the organ level, and crossed the alveolar-blood barrier to enter the bloodstream. The expression of α1-antitrypsin (AAT) was significantly reduced, which could be served as early COPD checkpoint on the lung-chips. Overall, the lung-on-a-chip provides a new platform for investigating the pulmonary toxicity of nanoplastics, demonstrating that PS-NPs can harm the alveolar-blood barrier, cause oxidative damage and inflammation, and increase the risk of COPD.

Advances of microfluidic lung chips for assessing atmospheric pollutants exposure

Atmospheric pollutants, including particulate matters, nanoparticles, bioaerosols, and some chemicals, have posed serious threats to the environment and the human's health. The lungs are the responsible organs for providing the interface betweenthecirculatory system and the external environment, where pollutant particles can deposit or penetrate into bloodstream circulation. Conventional studies to decipher the mechanismunderlying air pollution and human health are quite limited, due to the lack of reliable models that can reproduce in vivo features of lung tissues after pollutants exposure. In the past decade, advanced near-to-native lung chips, combining cell biology with bioengineered technology, present a new strategy for atmospheric pollutants assessment and narrow the gap between 2D cell culture and in vivo animal models. In this review, the key features of artificial lung chips and the cutting-edge technologies of the lung chip manufacture are introduced. The recent progresses of lung chip technologies for atmospheric pollutants exposure assessment are summarized and highlighted. We further discuss the current challenges and the future opportunities of the development of advanced lung chips and their potential utilities in atmospheric pollutants associated toxicity testing and drug screening.

Alternative Methods as Tools for Obesity Research: In Vitro and In Silico Approaches

The study of adipogenesis is essential for understanding and treating obesity, a multifactorial problem related to body fat accumulation that leads to several life-threatening diseases, becoming one of the most critical public health problems worldwide. In this review, we propose to provide the highlights of the adipogenesis study based on in vitro differentiation of human mesenchymal stem cells (hMSCs). We list in silico methods, such as molecular docking for identification of molecular targets, and in vitro approaches, from 2D, more straightforward and applied for screening large libraries of substances, to more representative physiological models, such as 3D and bioprinting models. We also describe the development of physiological models based on microfluidic systems applied to investigate adipogenesis in vitro. We intend to identify the main alternative models for adipogenesis evaluation, contributing to the direction of preclinical research in obesity. Future directions indicate the association of in silico and in vitro techniques to bring a clear picture of alternative methods based on adipogenesis as a tool for obesity research.

Towards an artificial human lung: modelling organ-like complexity to aid mechanistic understanding

Respiratory diseases account for over 5 million deaths yearly and are a huge burden to healthcare systems worldwide. Murine models have been of paramount importance to decode human lung biology in vivo, but their genetic, anatomical, physiological and immunological differences with humans significantly hamper successful translation of research into clinical practice. Thus, to clearly understand human lung physiology, development, homeostasis and mechanistic dysregulation that may lead to disease, it is essential to develop models that accurately recreate the extraordinary complexity of the human pulmonary architecture and biology. Recent advances in micro-engineering technology and tissue engineering have allowed the development of more sophisticated models intending to bridge the gap between the native lung and its replicates in vitro Alongside advanced culture techniques, remarkable technological growth in downstream analyses has significantly increased the predictive power of human biology-based in vitro models by allowing capture and quantification of complex signals. Refined integrated multi-omics readouts could lead to an acceleration of the translational pipeline from in vitro experimental settings to drug development and clinical testing in the future. This review highlights the range and complexity of state-of-the-art lung models for different areas of the respiratory system, from nasal to large airways, small airways and alveoli, with consideration of various aspects of disease states and their potential applications, including pre-clinical drug testing. We explore how development of optimised physiologically relevant in vitro human lung models could accelerate the identification of novel therapeutics with increased potential to translate successfully from the bench to the patient's bedside.

Assessing the Effect of Incretin Hormones and Other Insulin Secretagogues on Pancreatic Beta-Cell Function: Review on Mathematical Modelling Approaches

Mathematical modelling in glucose metabolism has proven very useful for different reasons. Several models have allowed deeper understanding of the relevant physiological and pathophysiological aspects and promoted new experimental activity to reach increased knowledge of the biological and physiological systems of interest. Glucose metabolism modelling has also proven useful to identify the parameters with specific physiological meaning in single individuals, this being relevant for clinical applications in terms of precision diagnostics or therapy. Among those model-based physiological parameters, an important role resides in those for the assessment of different functional aspects of the pancreatic beta cell. This study focuses on the mathematical models of incretin hormones and other endogenous substances with known effects on insulin secretion and beta-cell function, mainly amino acids, non-esterified fatty acids, and glucagon. We found that there is a relatively large number of mathematical models for the effects on the beta cells of incretin hormones, both at the cellular/organ level or at the higher, whole-body level. In contrast, very few models were identified for the assessment of the effect of other insulin secretagogues. Given the opportunities offered by mathematical modelling, we believe that novel models in the investigated field are certainly advisable.