Biology subjects

Schipper, R.

Publications and source records attributed to Schipper, R..

3 recordsLinked to original sources

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

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↗

bioRxiv2020

In Situ Unzipping of Long, High Molecular Weight DNA in Solid State Nanopores

Nanopores are an established paradigm in genome sequencing technology, with remarkable advances still being made today. All efforts continually address the challenges associated with rapid, accurate, high-throughput, and low cost detection, particularly with long-read length DNA. We report on the in situ melting and unzipping of long, high molecular weight DNA. At varying salt concentration, we directly compare the translocation conductance and speeds between SiN and graphene nanopores at sub-10 nm pore diameters. We observe the force-induced unzipping of dsDNA at higher salt concentrations than previously reported in literature. We observe free running translocation without secondary structures of ssDNA that is an order of magnitude longer than reported before. We hypothesize that the frayed single strands at the molecules end get captured with a higher likelihood than both ends together. In understanding this phenomena for long-read lengths, we continue to address the challenges revolving around future generations of sequencing technology. Statement of SignificanceGenome sequencing is an advancing field with applications in clinical diagnostics. However, the challenges of providing accurate identification of longer DNA molecules at low cost are still developing. While detection of long DNA molecules is established, the identification of its individual nucleotides presents its own set of challenges. By separating the hydrogen bonds between the two strands, individual nucleotides are made directly measurable. However, identification is hindered from the formation of secondary structures, where the single-stranded DNA sticks to itself. Previous studies only included short DNA molecules. We report in situ force-induced unzipping and translocation of long DNA without secondary structures almost an order of magnitude longer than reported before. Our findings present new experimental conditions and insights that progress the field towards high accuracy sequencing of individual long molecules.

biophysics↗