Dr Leonard J Nelson

Group Members

Anabel Martinez Lyons, Postdoctoral Research Associate

Debbie Neill, Research Assistant (UoE PhD Scholarship; Primary supervisor)

Callum Rafferty, UoE DTP PhD Fellowship (Doctoral adviser)

Modelling the health-to-disease transition in MASLD-MASH

Background 

Metabolic dysfunction-associate steatotic liver disease (MASLD; formerly, NAFLD) refers to a spectrum of metabolic liver disorders ranging from simple steatotic (fatty) liver disease (SLD) to inflammation-driven metabolic dysfunction-associated steatohepatitis (MASH). The mechanisms underlying the inflammation-driven transition from healthy liver to MASLD-MASH are largely ill-defined, primarily due to a lack of human-relevant models that faithfully recapitulate the disease. While standard preclinical in vitro models of MASLD and MASH have advanced our understanding of the disease, these models lack the tissue complexity crucial to emulating in vivo-like hepatic phenotypes. We are developing advanced organotypic multicellular human liver models with increased complexity that promote cell-cell/cell-matrix interactions and recapitulate the hepatic cellular environment more closely. Leveraging nutrient-excess models which emulate MASLD-MASH recapitulates parameters driving disease transition and progression. Integration of imaging, functional and omics data – with clinical validation - will allow us to identify molecular pathways and biomarkers involved in the MASLD-MASH transition and to test potential pharmacological interventions.

Research Vision

Using our human-relevant preclinical models of chronic liver disease, with in vivo and clinical validation, we aim to uncover signals, mechanisms, and biomarkers defining the Health-to-Disease transition in MASLD-MASH.

Research Overview

We are developing LiverACE – a modular human-relevant animal-free and multi-cellular in vitro system for applications in chronic liver disease. LiverACE is a 3D organotypic 5-cell system representing the human liver acinus – the functional unit of the liver. We use a multi-parametric approach, including phenotypic profiling (form, phenotype and function), multi-omics (secretomics, unbiased proteomics, focussed lipidomics; and spatial transcriptomics) to characterize and validate the models, leveraging advanced data integration pipelines. Our human iver models are benchmarked against extensive preclinical in vivo data (mouse DUAL model; mouse and zebrafish humanized models) as well as our clinical data hub (Halt-RONIN Consortium; SteatoSite.com) – providing read-across and model validation. This approach includes spatial transcriptomics analysis of human MASLD-MASH-Fibrosis and healthy liver tissue samples. The health-to-disease transition is modelled in vitro using a nutrient-excess cocktail resulting in simple steatosis (MASLD: lipid droplet deposition (LDD) and MASH (LDD + inflammation). Deconstruction of LiverACE provides modular context-specific models for in-depth analysis, including: Vascular (HepaRG:Endothelial cells); Inflammation (HepaRG:stellate cells); an Immunomodulation (HepaRG:Kupffer cells) models. 

Human liver-acinar-chip

The inflammation-driven transition from healthy liver to MASLD and MASH involves complex interactions between hepatocytes, nonparenchymal cells (NPCs), and extracellular matrix (ECM). These processes are poorly captured in standard preclinical hepatic cultures. We use the Human Emulation Microphysiological System, which provides a physiologically-relevant microenvironment integrating mechanical forces, fluid dynamics, and cell-cell/cell-matrix interactions. We have established a novel 5-cell human liver acinus-on-a-chip to investigate the role of hypoxia in inflammation-driven MASLD-MASH, pro-inflammatory cytokines driving disease transition and as potential correlative biomarkers (eg IL-32), and the HIF1a-PHD system as novel therapeutic targets.

3D spheroids

Our lab has established organotypic 3D acinar spheroids that demonstrate accurate MASLD-MASH modelling, including lipid droplet accumulation and inflammatory activation of immune cells - key features of in vivo MASLD-MASH pathogenesis. Confocal imaging (Phenix Opera Plus) of cultured human hepatic cells and spheroids has identified temporal cell-type specific disease phenotypes for hepatocytes, monocytes, and stellate cells. Holographic tomography (nanolive) shows dynamic and extensive lipid loading, as well as reduced cellular proliferation in MASH compared with the MASLD model and ‘healthy’ untreated controls. `Whereas, immunoblotting has revealed increased epithelial (ZO-1 and E-Cadherin) and reduced mesenchymal (N-Cadherin, SNAIL1, alpha-SMA, and Vimentin) biomarkers in MASH compared to both MASLD and control models, suggesting mesenchymal-epithelial-transition cell identity. This approach could help identify cell type-specific biomarkers that can reliably target different stages of the health-MASLD-MASH pathogenic spectrum

Cell behaviour

The biophysical mechanisms underlying fatty liver disease progression remain poorly understood and could be important to unveiling potential targets for diagnostic and therapeutic interventions. Our research explores how biophysical alterations in hepatic cells – including changes to barrier function, membrane properties, and adhesion - are linked to metabolic and functional perturbations and cellular stress mechanisms (XBP1 gradient) and how these events impact cellular behaviour and progression of fatty liver disease. We use quantitative, real-time, non-invasive and label-free impedance biosensing biochips to monitor parameters of cell behaviour (tight junctions; cell adhesion; membrane integrity); together with correlative biochemical approaches (functional assays) as well as FLIM/ Flipper to investigate quantitative changes in hepatic cell membrane tension, and lipid droplet profiling (Perilipins; focussed metabolomics). LD-mitochondrial interactions are being investigated at the ultrastructural level together with mitochondrial/ fatty acid β-oxidation as key structure-function alterations in MASLD-MASH.

Biographical Profile 

Leonard Nelson PhD FRSB received his doctorate from The University of Edinburgh (UoE) Faculty of Medicine in the Liver Cell Biology Laboratory. His PhD involved tissue engineering approaches for the development of bioartificial liver systems. He is a PI, and Senior Research Fellow in Human Liver Biological Engineering at the UoE Institute for BioEngineering and was previously principal scientist at the UoE Hepatology Lab at The Royal Infirmary of Edinburgh. Lenny’s research interests span the chronic liver disease (CLD) spectrum, developing the LiverACE system - focussing on human-relevant liver disease modelling, cell pathobiology, toxicology (DILI), and cancer biology. He is PI of UKRI Horizon project Halt-RONIN in human liver tissue modelling of the Health-to-Disease transition (MASLD-MASH); Horizon Europe grant, 2023-2027; and was Consortium Coordinator at submission.

Collaborators

Halt-RONIN Horizon Europe Consortium

Prof Javier Cubero (UCM, Madrid) Horizon Europe Consortium Coordinator

University of Edinburgh

Dr Pierre Bagnaninch (non-invasive technologies)

Prof Jonathan Fallowfield (Translational hepatology)

Prof Timothy Kendall (Liver pathology)

Dr Justyna Cholewa-Waclaw (Bioimaging; Phenix Opera Plus spinning disc confocal microscopy)

Dr Lucia Bandiera (Computational modelling)

Professor Prakash Ramachandran (Single-cell and Spatial technologies in fibrosis)

Dr Gareth Sullivan (iPSC organoid technologies; University of St Andrews)

Prof Alistair Elfick (Bioengineering)

Dr Charlie Wilson | Prof Steve Pollard | nanolive