Biology subjects

Hagberg, C. E.

Publications and source records attributed to Hagberg, C. E..

5 recordsLinked to original sources

bioRxiv2025

In vitro model of human subcutaneous adipocyte spheroids for studying mitochondrial dysfunction and mitochondria activating compounds

Mitochondrial abnormalities drive subcutaneous white adipose tissue dysfunction in obesity, leading to metabolic complications. A key challenge in obesity research is the lack of in vitro models to study human adipocyte mitochondria. Here, we establish a human subcutaneous adipocyte spheroid model to characterize mitochondrial metabolism under obesity-relevant conditions and drug exposure. Human preadipocyte spheroids were differentiated in ultra-low attachment plates for 3 weeks in media free of thiazolidinediones. The differentiated adipocyte spheroids showed increased lipid accumulation, adipogenic gene expression, mitochondrial respiration and adiponectin secretion, and a proper response to hormonal stimulation. Lipid mixture administration during differentiation induced metabolic disturbances including mitochondrial respiration failure associated with increased mitochondrial biogenesis. Post-differentiation treatment with rosiglitazone, a peroxisome proliferator-activated receptor {gamma} agonist, improved mitochondrial bioenergetics and adiponectin secretion in lipid mixture-administered adipocyte spheroids. Our model enables precise measurement of adipocyte mitochondria under various conditions, providing a platform for mitochondria-related research and drug discovery in obesity.

molecular biology↗

bioRxiv2024

Defining the Vascular Niche of Human Adipose Tissue Across Metabolic Conditions

IntroductionAdipose tissue homeostasis depends on a healthy vascular network. Vascular malfunction is a hallmark of obesity1, and vascular endothelial dysfunction, in particular, accelerates metabolic diseases, including obesity and diabetes. Single-cell transcriptomics studies have mapped the cellular landscape of human white adipose tissue (WAT)2-8. However, the vascular niche remains relatively undefined9, especially regarding its heterogeneity, function, and role in metabolic disease. To address this gap, we created a single-cell transcriptome atlas of human subcutaneous adipose tissue (SAT), comprising nearly 70,000 vascular cells from 65 individuals. We characterized seven canonical adipose tissue endothelial cell (AdEC) subtypes and identified a distinct heterogenous population, here referred to as sub-AdECs. Sub-AdECs exhibit gene signatures characteristic of multiple cell types, including mesenchymal, adipocytic, and immune, suggesting they possess diverse properties and identities. Through computational analyses and whole-mount imaging, we validated the occurrence of sub-AdECs and show that these cells likely arise through endothelial-mesenchymal transition (EndMT), the modulation of which limits obesity-associated adipose tissue inflammation and fibrosis. Furthermore, we compared the transcriptomes of vascular cells from individuals living with or without obesity and type 2 diabetes and find metabolic disease-associated inflammatory and fibrotic transcriptomic patterns. The atlas and accompanying analyses establish a solid foundation for investigations into the biology of the adipose tissue vascular niche and its contribution to the pathogenesis of metabolic disease.

cell biology↗

bioRxiv2024

Titration-WB: A methodology for accurate quantitative protein determination overcoming reproducibility errors

Western blot (WB) technique is widely used to identify and quantify proteins in biological samples, but it is poorly accurate and precise for quantitative purposes. Merging the WB with the titration assay, we established a reliable method for protein quantification based on the slope of the linear function for signal-intensity/total protein loaded. Titration-WB unravels systematic and operator errors, compensates for problems in antibody affinity/avidity, and permits trustworthy inter-WB comparison.

biochemistry↗

bioRxiv2024

Adipose tissue microvascular endothelial cells form a tight vascular barrier that selectively transcytoses fatty acid tracers

In organs with continuous, non-leaky capillaries like white adipose tissue and the heart, microvascular endothelial cells (ECs) serve as a vital barrier, facilitating nutrient delivery to underlying tissues. While capillary heterogeneity between organs is well established, how these vascular layers have adapted their key functions - such as fatty acid transport - to their respective organs remains unclear, largely due to the lack of organotypic endothelial model systems. Here we demonstrate that the vascular barrier in white adipose tissue, a crucial organ for whole-body fatty acid handling, exhibits comparable impermeability to that of heart and muscle. To investigate if the adipose endothelium possesses tissue-specific functions for facilitating fatty acid transport, we developed an in vitro dual tracing-system that allows simultaneous monitoring of barrier integrity and fatty acid transport dynamics by modifying the classic transwell culture. Using this system, we can show human adipose-derived primary ECs selectively transport fluorescent fatty acid tracers while excluding other tracers like dextrans, a phenomenon not observed in other cultured human ECs. Additionally, our findings reveal EC-type specific responses to various transcytosis inhibitors. Our results underscore the unique characteristics of the adipose endothelium and enhances our understanding of how microvascular permeability and transport dynamics have adapted to their specific organ physiology.

cell biology↗

bioRxiv2021

Hypertrophied human adipocyte spheroids as in vitro model of weight gain and adipose tissue dysfunction

The rise in obesity prevalence has created an urgent need for new and improved methods to study human adipocytes and the pathogenic effects of weight gain in vitro. Despite numerous studies showing the advantages of culturing adipocyte progenitors as 3D structures, the majority continue using traditional 2D cultures which result in small, multilocular adipocytes with poor representability. We hypothesized that providing differentiating pre-adipocytes with a vascular growth niche would mimic in vivo adipogenesis and improve the differentiation process. Here we present a simple, easily applicable culture protocol that allows for the differentiation and culturing of human adipocytes with a more unilocular morphology and larger lipid droplets than previous protocols. We moreover offer a protocol for inducing adipocyte enlargement in vitro, resulting in larger lipid droplets and development of several key features of adipocyte dysfunction, including altered adipokine secretions and impaired lipolysis. Taken together, our hypertrophied human adipocyte spheroids offer an improved culture system for studying the cellular and molecular mechanisms causing metabolic dysfunction and inflammation during weight gain.

cell biology↗