Human Tissue Physiology Research Articles

DNA methylation in small cell lung cancer

AbstractSmall cell lung cancer (SCLC) originates from pulmonary neuroendocrine cells and accounts for approximately 15% of lung cancer incidents. Patients with SCLC have a very low survival rate due to fast progression and early metastasis. Despite the recent approval of immune checkpoint blockade for treatment of SCLC by US FDA, conventional platinum chemotherapy remains the first‐line treatment which always develops quick drug resistance. To define targets for diagnosis and treatment, SCLC has been categorized by different molecular markers. The most popular markers include genomic mutations in tumour suppressor genes such as TP53 and RB1 and expression of lineage‐specific transcription factors (TFs), that is ASCL1, NEUROD1, POU2F3 and YAP1. As DNA methylation is an important hallmark of cancer, efforts were made to investigate the mechanisms of DNA methylation involved in SCLC progression. Indeed, SCLC has distinct pattern of DNA methylation due to its different features compared to non‐SCLC and other tumours. In this review, we summarized the mechanisms of DNA methylation in SCLC which are associated with lineage‐specific TFs, cell proliferation, anti‐apoptosis, drug resistance, immune evasion and metastasis. We foresaw the challenges of applying DNA methylation in clinical diagnosis and treatment and discussed new approaches and technologies to overcome them. Combined with other gene regulatory information such as transcription and histone modification, DNA methylation/hydroxymethylation in SCLC will be resolved at single‐cell resolution to dissect the tumour microenvironment. The huge multiomics data will be processed and integrated with clinical data such as clinical images and pathological histochemistry by artificial intelligence and cloud computing. Circulating cell‐free DNA methylation will greatly enhance early diagnosis and prognosis prediction. New organoid and organ chip models will break through the obstacles of sampling limitation, faithfully simulate the physiology of human tissues and enable examining spatiotemporal DNA methylation during SCLC progression.

Design and engineering of organ-on-a-chip.

Organ-on-a-chip (OOC) is an emerging interdisciplinary technology that reconstitutes the structure, function, and physiology of human tissues as an alternative to conventional preclinical models for drug screening. Over the last decade, substantial progress has been made in mimicking tissue- and organ-level functions on chips through technical advances in biomaterials, stem cell engineering, microengineering, and microfluidic technologies. Structural and engineering constituents, as well as biological components, are critical factors to be considered to reconstitute the tissue function and microenvironment on chips. In this review, we highlight critical engineering technologies for reconstructing the tissue microarchitecture and dynamic spatiotemporal microenvironment in OOCs. We review the technological advances in the field of OOCs for a range of applications, including systemic analysis tools that can be integrated with OOCs, multiorgan-on-chips, and large-scale manufacturing. We then discuss the challenges and future directions for the development of advanced end-user-friendly OOC systems for a wide range of applications.

Relative infectivity of the SARS-CoV-2 Omicron variant in human alveolar cells.

With the continuous emergence of highly transmissible SARS-CoV-2 variants, the comparison of their infectivity has become a critical issue for public health. However, a direct assessment of the viral characteristic has been challenging because of the lack of appropriate experimental models and efficient methods. Here, we integrated human alveolar organoids and single-cell transcriptome sequencing to facilitate the evaluation. In a proof-of-concept study with four highly transmissible SARS-CoV-2 variants, including GR (B.1.1.119), Alpha (B.1.1.7), Delta (B.1.617.2), and Omicron (BA.1), a rapid evaluation of the relative infectivity was possible. Our system demonstrates that the Omicron variant is 5- to 7-fold more infectious to human alveolar cells than the other SARS-CoV-2 variants at the initial stage of infection. To our knowledge, for the first time, this study measures the relative infectivity of the Omicron variant under multiple virus co-infection and provides new experimental procedures that can be applied to monitor emerging viral variants.

571 Human Hair Follicles can “Taste”: Stimulation of the Bitter Taste Receptor TAS2R4 Inhibits Hair Growth Ex Vivo by Up-Regulating TGF-β2

Besides taste buds, several other tissues express taste receptors (TR), where these exert various non-gustatory functions, e.g. in immunity, metabolism, endocrinology and/or reproduction. Human skin expresses the bitter TR, TAS2R4, whose functions in skin biology remain unknown. Since we show here that the epithelium of human scalp hair follicles (HFs) prominently and hair cycle-dependently expresses functional TAS2R4, we have explored these human chemosensory (mini-)organs as accessible model systems to dissect non-classical TR functions in human tissue physiology.

Tunable 3D Hydrogel Microchannel Networks to Study Confined Mammalian Cell Migration.

Cells adapt and move due to chemical, physical, and mechanical cues from their microenvironment. It is therefore important to create materials that mimic human tissue physiology by surface chemistry, architecture, and dimensionality to control cells in biomedical settings. The impact of the environmental architecture is particularly relevant in the context of cancer cell metastasis, where cells migrate through small constrictions in their microenvironment to invade surrounding tissues. Here, a synthetic hydrogel scaffold with an interconnected, random, 3D microchannel network is presented that is functionalized with collagen to promote cell adhesion. It is shown that cancer cells can invade such scaffolds within days, and both the microarchitecture and stiffness of the hydrogel modulate cell invasion and nuclear dynamics of the cells. Specifically, it is found that cell migration through the microchannels is a function of hydrogel stiffness. In addition to this, it is shown that the hydrogel stiffness and confinement, influence the occurrence of nuclear envelope ruptures of cells. The tunable hydrogel microarchitecture and stiffness thus provide a novel tool to investigate cancer cell invasion as a function of the 3D microenvironment. Furthermore, the material provides a promising strategy to control cell positioning, migration, and cellular function in biological applications, such as tissue engineering.

Time-of-flight resolved light field fluctuations reveal deep human tissue physiology

Red blood cells (RBCs) transport oxygen to tissues and remove carbon dioxide. Diffuse optical flowmetry (DOF) assesses deep tissue RBC dynamics by measuring coherent fluctuations of multiply scattered near-infrared light intensity. While classical DOF measurements empirically correlate with blood flow, they remain far-removed from light scattering physics and difficult to interpret in layered media. To advance DOF measurements closer to the physics, here we introduce an interferometric technique, surmounting challenges of bulk motion to apply it in awake humans. We reveal two measurement dimensions: optical phase, and time-of-flight (TOF), the latter with 22 picosecond resolution. With this multidimensional data, we directly confirm the unordered, or Brownian, nature of optically probed RBC dynamics typically assumed in classical DOF. We illustrate how incorrect absorption assumptions, anisotropic RBC scattering, and layered tissues may confound classical DOF. By comparison, our direct method enables accurate and comprehensive assessment of blood flow dynamics in humans.

Autophagy is essential for maintaining the growth of a human (mini-)organ: Evidence from scalp hair follicle organ culture.

Autophagy plays a crucial role in health and disease, regulating central cellular processes such as adaptive stress responses, differentiation, tissue development, and homeostasis. However, the role of autophagy in human physiology is poorly understood, highlighting a need for a model human organ system to assess the efficacy and safety of strategies to therapeutically modulate autophagy. As a complete, cyclically remodelled (mini-)organ, the organ culture of human scalp hair follicles (HFs), which, after massive growth (anagen), spontaneously enter into an apoptosis-driven organ involution (catagen) process, may provide such a model. Here, we reveal that in anagen, hair matrix keratinocytes (MKs) of organ-cultured HFs exhibit an active autophagic flux, as documented by evaluation of endogenous lipidated Light Chain 3B (LC3B) and sequestosome 1 (SQSTM1/p62) proteins and the ultrastructural visualization of autophagosomes at all stages of the autophagy process. This autophagic flux is altered during catagen, and genetic inhibition of autophagy promotes catagen development. Conversely, an anti–hair loss product markedly enhances intrafollicular autophagy, leading to anagen prolongation. Collectively, our data reveal a novel role of autophagy in human hair growth. Moreover, we show that organ-cultured scalp HFs are an excellent preclinical research model for exploring the role of autophagy in human tissue physiology and for evaluating the efficacy and tissue toxicity of candidate autophagy-modulatory agents in a living human (mini-)organ.

A 3-dimensional fibre scaffold as an investigative tool for studying the morphogenesis of isolated plant pells.

BackgroundCell culture methods allow the detailed observations of individual plant cells and their internal processes. Whereas cultured cells are more amenable to microscopy, they have had limited use when studying the complex interactions between cell populations and responses to external signals associated with tissue and whole plant development. Such interactions result in the diverse range of cell shapes observed in planta compared to the simple polygonal or ovoid shapes in vitro. Microfluidic devices can isolate the dynamics of single plant cells but have restricted use for providing a tissue-like and fibrous extracellular environment for cells to interact. A gap exists, therefore, in the understanding of spatiotemporal interactions of single plant cells interacting with their three-dimensional (3D) environment. A model system is needed to bridge this gap. For this purpose we have borrowed a tool, a 3D nano- and microfibre tissue scaffold, recently used in biomedical engineering of animal and human tissue physiology and pathophysiology in vitro.ResultsWe have developed a method of 3D cell culture for plants, which mimics the plant tissue environment, using biocompatible scaffolds similar to those used in mammalian tissue engineering. The scaffolds provide both developmental cues and structural stability to isolated callus-derived cells grown in liquid culture. The protocol is rapid, compared to the growth and preparation of whole plants for microscopy, and provides detailed subcellular information on cells interacting with their local environment. We observe cell shapes never observed for individual cultured cells. Rather than exhibiting only spheroid or ellipsoidal shapes, the cells adapt their shape to fit the local space and are capable of growing past each other, taking on growth and morphological characteristics with greater complexity than observed even in whole plants. Confocal imaging of transgenic Arabidopsis thaliana lines containing fluorescent microtubule and actin reporters enables further study of the effects of interactions and complex morphologies upon cytoskeletal organisation both in 3D and in time (4D).ConclusionsThe 3D culture within the fibre scaffolds permits cells to grow freely within a matrix containing both large and small spaces, a technique that is expected to add to current lithographic technologies, where growth is carefully controlled and constricted. The cells, once seeded in the scaffolds, can adopt a variety of morphologies, demonstrating that they do not need to be part of a tightly packed tissue to form complex shapes. This points to a role of the immediate nano- and micro-topography in plant cell morphogenesis. This work defines a new suite of techniques for exploring cell-environment interactions.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0581-7) contains supplementary material, which is available to authorized users.

Design of surface wave active beds based on human tissue physiology

A surface wave distributed actuation method and its proper design for safely transporting bedridden patients is explored in this paper. First, the basic principle of surface wave distributed actuation is presented, including a new kinematic feature that augments natural surface wave motion for enhanced transport efficiency of humans and elastic bodies. Kinematic modeling and analysis reveals that an object can be transferred by a simplified actuator architecture that makes the concept amenable to hardware realization. A proof of concept prototype demonstrates that heavily loaded rigid objects, elastic objects and humans can be transported. Human tissue physiology is studied to establish worst-case criteria for safe and healthy interactions between the human and the support surface that depends on the duration of interaction. Static models are developed and solved using finite element methods to calculate interaction stresses for realistic, worst-case human-surface wave interaction scenarios. Based on these results a new two-mode surface is designed to secure safe interactions for both long-term support and short term transport tasks.