A high-throughput 3D X-ray histology facility for biomedical research and preclinical applications

Background

The University of Southampton, in collaboration with the University Hospital Southampton (UHS) NHS Foundation Trust and industrial partners, has been at the forefront of developing three-dimensional (3D) imaging workflows using X-ray microfocus computed tomography (μCT) -based technology. This article presents the outcomes of these endeavours and highlights the distinctive characteristics of a μCT facility tailored explicitly for 3D X-ray Histology, with a primary focus on applications in biomedical research and preclinical and clinical studies.

Methods

The UHS houses a unique 3D X-ray Histology (XRH) facility, offering a range of services to national and international clients. The facility employs specialised μCT equipment explicitly designed for histology applications, allowing whole-block XRH imaging of formalin-fixed and paraffin-embedded tissue specimens. It also enables correlative imaging by combining μCT imaging with other microscopy techniques, such as immunohistochemistry (IHC) and serial block-face scanning electron microscopy, as well as data visualisation, image quantification, and bespoke analysis.

Results

Over the past seven years, the XRH facility has successfully completed over 120 projects in collaboration with researchers from 60 affiliations, resulting in numerous published manuscripts and conference proceedings. The facility has streamlined the μCT imaging process, improving productivity and enabling efficient acquisition of 3D datasets.

Discussion & Conclusions

The 3D X-ray Histology (XRH) facility at UHS is a pioneering platform in the field of histology and biomedical imaging. To the best of our knowledge, it stands out as the world's first dedicated XRH facility, encompassing every aspect of the imaging process, from user support to data generation, analysis, training, archiving, and metadata generation. This article serves as a comprehensive guide for establishing similar XRH facilities, covering key aspects of facility setup and operation. Researchers and institutions interested in developing state-of-the-art histology and imaging facilities can utilise this resource to explore new frontiers in their research and discoveries.

Correlative 3D Imaging and Microfluidic Modelling of Human Pulmonary Lymphatics using Immunohistochemistry and High-resolution μCT

Lung lymphatics maintain fluid homoeostasis by providing a drainage system that returns fluid, cells and metabolites to the circulatory system. The 3D structure of the human pulmonary lymphatic network is essential to lung function, but it is poorly characterised. Image-based 3D mathematical modelling of pulmonary lymphatic microfluidics has been limited by the lack of accurate and representative image geometries. This is due to the microstructural similarity of the lymphatics to the blood vessel network, the lack of lymphatic-specific biomarkers, the technical limitations associated with image resolution in 3D, and sectioning artefacts present in 2D techniques. We present a method that combines lymphatic specific (D240 antibody) immunohistochemistry (IHC), optimised high-resolution X-ray microfocus computed tomography (μCT) and finite-element mathematical modelling to assess the function of human peripheral lung tissue. The initial results identify lymphatic heterogeneity within and between lung tissue. Lymphatic vessel volume fraction and fractal dimension significantly decreases away from the lung pleural surface (p < 0.001, n = 25 and p < 0.01, n = 20, respectively). Microfluidic modelling successfully shows that in lung tissue the fluid derived from the blood vessels drains through the interstitium into the lymphatic vessel network and this drainage is different in the subpleural space compared to the intralobular space. When comparing lung tissue from health and disease, human pulmonary lymphatics were significantly different across five morphometric measures used in this study (p ≤ 0.0001). This proof of principle study establishes a new engineering technology and workflow for further studies of pulmonary lymphatics and demonstrates for the first time the combination of correlative μCT and IHC to enable 3D mathematical modelling of human lung microfluidics at micrometre resolution.

Secretion of lactoferrin and lysozyme by cultures of human airway epithelium

Lactoferrin and lysozyme are important antimicrobial compounds of airway surface liquid, derived predominantly from serous cells of submucosal glands but also from surface epithelium. Here we compared release of these compounds from the following human cell cultures: primary cultures of tracheal epithelium (HTE), Calu-3 cells (a lung adenocarcinoma cell line frequently used as a model of serous gland cells), 16HBE14o- cells (an SV40 transformed line from airway surface epithelium), T84 cells (a colon carcinoma cell line), and human foreskin fibroblasts (HFF). For lysozyme, baseline secretory rates were in the order Calu-3 > 16HBE14o- > HTE ≈ T84 > HFF = 0; for lactoferrin, the only cell type showing measurable release was HTE; for mucus, HTE > Calu-3 > 16HBE14o- ≈ T84 > HFF = 0. A wide variety of neurohumoral agents and inflammatory stimuli was without effect on lactoferrin and lysozyme release from HTE or Calu-3 cells, although forskolin did stimulate secretion of water and lysozyme from Calu-3 cells. However, the concentration of lysozyme in the forskolin-induced secretions was much less than in airway gland secretions. Thus our data cast doubt on the utility of Calu-3 cells as a model of airway serous gland cells but do suggest that HTE could prove highly suitable for studies of mucin synthesis and release.

Differentiation of fluid, visual, and simultaneous cognitive tasks

The constructs of fluid reasoning and spatial visualization (Horn, 1989) as well as the construct of simultaneous processing (Luria, 1966) have been tapped by various cognitive assessment batteries. In order to determine whether these constructs could be differentiated from one another, factor analyses of subtest scores from six cognitive tasks were conducted. Fluid reasoning, spatial visualization, and simultaneous processing emerged as separate factors in the analysis, supporting the hypothesis that these constructs can be differentiated in psychoeducational testing. These results extend the findings of a preliminary study which found factorial differentiation between fluid and simultaneous reasoning.

Computational simulation of extravehicular activity dynamics during a satellite capture attempt

A more quantitative approach to the analysis of astronaut extravehicular activity (EVA) tasks is needed because of their increasing complexity, particularly in preparation for the on-orbit assembly of the International Space Station. Existing useful EVA computer analyses produce either high-resolution three-dimensional computer images based on anthropometric representations or empirically derived predictions of astronaut strength based on lean body mass and the position and velocity of body joints but do not provide multibody dynamic analysis of EVA tasks. Our physics-based methodology helps fill the current gap in quantitative analysis of astronaut EVA by providing a multisegment human model and solving the equations of motion in a high-fidelity simulation of the system dynamics. The simulation work described here improves on the realism of previous efforts by including three-dimensional astronaut motion, incorporating joint stops to account for the physiological limits of range of motion, and incorporating use of constraint forces to model interaction with objects. To demonstrate the utility of this approach, the simulation is modeled on an actual EVA task, namely, the attempted capture of a spinning Intelsat VI satellite during STS-49 in May 1992. Repeated capture attempts by an EVA crewmember were unsuccessful because the capture bar could not be held in contact with the satellite long enough for the capture latches to fire and successfully retrieve the satellite.

Regional Forest Fragmentation and the Nesting Success of Migratory Birds

Forest fragmentation, the disruption in the continuity of forest habitat, is hypothesized to be a major cause of population decline for some species of forest birds because fragmentation reduces nesting (reproductive) success. Nest predation and parasitism by cowbirds increased with forest fragmentation in nine midwestern (United States) landscapes that varied from 6 to 95 percent forest cover within a 10-kilometer radius of the study areas. Observed reproductive rates were low enough for some species in the most fragmented landscapes to suggest that their populations are sinks that depend for perpetuation on immigration from reproductive source populations in landscapes with more extensive forest cover. Conservation strategies should consider preservation and restoration of large, unfragmented "core" areas in each region.

Patient mislabeling of symptoms: implications for patient-physician communication and medical outcome

Mislabeling of symptoms was studied in a group of 587 chronic asthmatic patients. Results indicated a wide variation in both the frequency and type of mislabeling, with over 26 per cent of the patients mislabeling one or more nonairways obstruction symptom clusters as being an asthma attack. Several demographic and personality factors were found to correlate with mislabeling. Finally, mislabeling was associated with medical outcome, with mislabelers being 40 per cent more likely than nonmislabelers to be rehospitalized for their asthma within six months of discharge.

The battery of asthma illness behavior, II: independence from airways hyperreactivity

Bronchial asthma is an illness particularly susceptible to psychological and behavioral exacerbation and perpetuation. The Battery of Asthma Illness Behavior has demonstrated a remarkable ability to identify such psychomaintenance potentials in chronic asthmatic patients. The present study advances previous research by showing that BAIB scores are independent of degree of airways hyperreactivity. This finding strengthens the assertion that the BAIB assesses psychomaintenance potentials independent from the objective medical parameters of the illness.