Biology subjects

Engelse, M. A.

Publications and source records attributed to Engelse, M. A..

6 recordsLinked to original sources

bioRxiv2026

Partial decellularization of kidneys during prolonged acellular perfusion

Long-term ex situ machine perfusion of donor organs is an emerging clinical strategy that creates a window for advanced therapeutic interventions. Replacing donor endothelial cells during machine perfusion with recipient endothelium could conceal the allogeneic epithelium from the recipients (humoral) immune response. We postulated that brief exposure to low concentrations of decellularizing agents could selectively remove vascular endothelium. Porcine kidneys were partially decellularized with five 2-minute infusions of either 0.01%, 0.1% or 1.0% SDS during acellular perfusion. As proof-of-concept, fluorescently-labelled porcine endothelial colony forming cells (ECFCs) were infused into the renal vein and artery of a partially decellularized kidney. Tissue analysis identified 0.1% SDS effectively removed endothelial cells from glomerular and peritubular capillaries. Infused ECFCs could be found back within the glomeruli. However, partial decellularization significantly impaired renal flow and increased vascular resistance. While partial decellularization successfully removed donor endothelium, the loss of vascular patency limits its clinical potential. Future research should prioritize modifying rather than removing donor endothelial cells.

bioengineering↗

bioRxiv2025

Beta hydroxybutyrate alters beta cell identity and function in human islets

Fasting alters insulin secretion in humans and islet cell composition in mice. Fasting triggers ketogenesis, which increases beta hydroxybutyrate (BHB) levels. BHB is a signaling molecule that alters insulin secretion in primary islets. We hypothesized that BHB alters human islet cell composition and identity. Primary human islets were cultured with R-BHB or its non-metabolizable enantiomer, S-BHB. Human islets cultured with R-BHB, but not S-BHB, resulted in an increased C-peptide-glucagon+ to C-peptide+glucagon- cell ratio, and an increased frequency of C-peptide+glucagon+ bihormonal cells and NKX6.1+glucagon+ cells. Single-cell transcriptomics revealed upregulation of alpha cell identity genes in R-BHB treated islet beta cells. Alterations in beta cell identity were accompanied by increased basal insulin secretion in response to low glucose, and a reduced insulin stimulation index in response to high glucose. The differential effects of the two BHB enantiomers on islet cell composition indicated that ketone metabolism is involved in islet cell identity change. Supporting this hypothesis, a subpopulation of beta cells in islets treated with R-BHB characterized by low ketolysis genes, OXCT1 and ACAT1, did not show altered alpha and beta cell identity genes. Additionally, primary islets from type 2 diabetes donors, which exhibited reduced OXCT1 and ACAT1 expression relative to donors without diabetes, did not display altered islet cell composition and beta cell function from R-BHB treatment. Our findings uncover a novel role of BHB in modulating beta cell identity, with potential implications for islet function in states with chronically elevated ketone concentrations.

cell biology↗

bioRxiv2025

Normothermic human kidney preservation drives iron accumulation and ferroptosis

Ex vivo normothermic machine perfusion has been proposed to protect deceased donor organs, promoting metabolic recovery and allowing quality assessment. However, its benefits for preserving deceased donor kidneys remain ambiguous. We postulate that the use of red blood cells (RBCs) as oxygen carriers and associated secondary hemolysis may in fact cause renal injury, offsetting potential advantages. During 48-hour normothermic perfusion of seven human deceased donor kidneys, we observed progressive hemolysis, leading to iron accumulation in perfusate, tissue, and urine. Untargeted lipidomic analysis revealed profound increases in oxidized phospholipid species in perfused kidneys, pointing towards iron-dependent cell death known as ferroptosis. Next, in twelve additional human kidney perfusions, we demonstrate that either dialysis-based free hemoglobin removal or cell-free perfusion attenuates hemolysis-driven iron accumulation, phospholipid peroxidation, and acute kidney injury. Our findings highlight the pathological role of hemolysis and iron on the kidney, urging restraint in the clinical application of RBC-based kidney perfusion.

physiology↗

bioRxiv2024

Secretome analysis of human and rat pancreatic islets co-cultured with adipose-derived stromal cells reveals a signature with enhanced regenerative capacities

Pancreatic islet transplantation (PIT), a promising treatment for Type 1 Diabetes (T1D), encounters challenges in the pre- and post-transplantation phases. Co-culturing or co-transplantation of islets with mesenchymal stromal cells (MSC), known for their regenerative properties, emerged as a potential solution and was shown to increase islet function and improve PIT outcomes. This study explored the changes in the islets secretion signature (secretome) when co-cultured with adipose-derived stromal cells (ASC), an MSC subtype. The secretome profile of islets and co-cultures under various stressors, i.e., cytokines, high glucose, hypoxia, and a combination of hypoxia and high glucose, was investigated. The results shed light on the potential mechanisms through which ASC support islets functional survival. Co-culturing pancreatic islets with ASC induced substantial proteomic changes, impacting pathways crucial for energy metabolism, angiogenesis, extracellular matrix organization, and immune responses. The analysis of key signaling molecules (VEGF, PDGF, bFGF, Collagen I alpha 1, IL-1, and IL-10) revealed alterations influenced by the culturing conditions and the presence of the ASC. In vitro functional assays using the secretomes also demonstrated their potential to differentially influence angiogenic processes, enhance collagen deposition, and modulate the immune system based on the conditions in which they were generated. These findings offer valuable insights into the potential of ASC co-culturing to address challenges in PIT, paving the way for enhanced therapeutic interventions in T1D and regenerative medicine. HighlightsO_LIBoth in-silico and in-vitro data support that co-culturing pancreatic islets with ASC enhances islet function. C_LIO_LICo-culturing islets with ASC induces changes in the secretome, impacting pathways related to energy metabolism, angiogenesis, extracellular matrix organization, and immune response. C_LIO_LIKey signaling molecules, including VEGF, PDGF, bFGF, Collagen I alpha 1, IL-1, and IL-10, are differentially affected by various co-culturing conditions. C_LI

cell biology↗

bioRxiv2023

Advancing multi-day ex vivo kidney perfusion using spatially resolved metabolomics

The ability to preserve metabolically active kidneys ex vivo for multiple days may permit reconditioning, repair and regeneration of deceased donor kidneys. However, the kidneys high metabolic demand limits its functional preservation. Current approaches focus on normothermic machine perfusion (NMP) at 37{degrees}C or hypothermic machine perfusion (HMP) at 4-8{degrees}C. At normothermia, kidneys are metabolically active but ex vivo preservation is limited to hours. During hypothermia kidneys can be preserved up to 24 hours but are metabolically inactive and suffer cold-induced injury. Therefore, we revisited sub normothermic perfusion (at 25{degrees}C) as an alternative approach to preserve human kidneys in a metabolically active state for extended periods of time. In a custom-made platform that includes a cell-free perfusate enriched with TCA cycle fuels, urine recirculation, and continuous hemofiltration we perfused discarded human kidneys up to 8 days. Using spatially resolved single cell resolution isotope tracing we demonstrate active metabolism in all the different renal cell types over this period. However, beyond 4 days cell composition of nephron segments assessed with spatial lipidomics changed substantially and injury markers such as NGAL and LDH increased in the perfusate. Up to 4 days, perfused human discarded donor kidneys maintained metabolic fluxes, functional parameters and allow for reperfusion using a porcine auto transplantation model. These data underpin that extended multi-day metabolic preservation of human kidneys is achievable using a sub normothermic perfusion platform.

bioengineering↗

bioRxiv2019

Oxidative stress in alpha and beta cells as a selection criterion for biocompatible biomaterials

The clinical success of islet transplantation is limited by factors including acute ischemia, stress upon transplantation, and delayed vascularization. Islets experience high levels of oxidative stress due to delayed vascularization after transplantation and this can be further aggravated by their encapsulation and undesirable cell-biomaterial interactions. To identify biomaterials that would not further increase oxidative stress levels and that are also suitable for manufacturing a beta cell encapsulation device, we studied five clinically approved polymers for their effect on oxidative stress and islet (alpha and beta cell) function. We found that 300 poly(ethylene oxide terephthalate) 55/poly(butylene terephthalate) 45 (PEOT/PBT300) was more resistant to breakage and more elastic than other biomaterials, which is important for its immunoprotective function. In addition, PEOT/PBT300 did not induce oxidative stress or reduce viability in MIN6 beta cells, and even promoted protective endogenous antioxidant expression over 7 days. Importantly, PEOT/PBT300 is one of the biomaterials we studied that did not interfere with insulin secretion in human islets. These data indicate that PEOT/PBT300 may be a suitable biomaterial for an islet encapsulation device.

cell biology↗