Biology subjects

Schalkwijk, C. G.

Publications and source records attributed to Schalkwijk, C. G..

4 recordsLinked to original sources

bioRxiv2026

Extracellular methylglyoxal; the passage across brain endothelial cells and the effect on barrier function

BackgroundMethylglyoxal (MGO), a highly reactive by-product of glycolysis, has been associated with cognitive decline and Alzheimers disease, though the mechanistic role of MGO remains unclear. Moreover, conflicting findings exist regarding MGOs toxicity on the blood-brain barrier (BBB). This study investigated whether MGO can cross the BBB under physiologically relevant conditions and whether MGO affects BBB permeability. MethodsMice were intravenously injected with highly purified home-made MGO or PBS, and MGO concentration was measured at five timepoints in the cerebral cortex up to 4 hours after injection. MGO toxicity was screened on a human brain endothelial cell line (hCMEC/D3) using a live/dead assay prior to the study of selected MGO concentrations and on hiPSC-derived brain microvascular endothelial cells (EECM-BMECs). EECM-BMECs were cultured on Transwell(R) inserts, and barrier function was assessed by sodium fluorescein permeability and transendothelial passage of 13C3-MGO quantified by UPLC-MS/MS. ResultsMGO levels in the mouse cortex did not increase post-injection. MGO was not toxic to hCMEC/D3 cells, and it had no impact on barrier properties of EECM-BMECs. After 1-hour exposure, [~]13% of total 13C3-MGO was recovered in its free form, and only [~]1% of supplemented MGO was recovered from the abluminal side. ConclusionMGO does not cross the BBB in vivo and does not affect barrier properties of a human in vitro model of the BBB. In vitro MGO passage across the BBB is minimal. These findings suggest that circulating MGO is unlikely to directly affect neuronal function via BBB disruption or enter the brain in its free from.

neuroscience↗

bioRxiv2025

Linking arterial biomechanics, contractility, and microstructure: A novel platform for combined structure-function assessment in murine arteries under physiological conditions

BackgroundEx vivo characterization of arterial viscoelastic properties shows arterial stiffness and contractility to depend on both axial stretch and dynamic pressurization. While these arterial properties are the subject of extensive ex vivo research due to their relevance to vascular pathophysiology, only few experimental approaches mimic both physiological axial stretch and dynamic pressurization when characterizing arterial biomechanics, vasoreactivity, and tissue microstructure. To fill this gap, we developed a custom dynamic biaxial pressure myograph compatible with two-photon laser scanning microscopy (TPLSM). MethodsWe studied five murine carotid artery segments. Sample viscoelastic behaviour was characterized by quasi-static and dynamic pressurization experiments at and around physiological axial stretch, as well as quasi-static stretching at physiological pressures. In addition, vasoconstriction in response to 2 {micro}M phenylephrine was measured during dynamic pressurization and with axial loads that mimicked physiological conditions. Lastly, arterial collagen, elastin, and cell nuclei were imaged using TPLSM with the sample at physiological axial stretch and pressurized at 100 mmHg. ResultsThe setup enabled capture of the non-linear biaxial viscoelastic behaviour of the arterial wall as well as the viscoelastic stiffening with dynamic pressurization. Modulation of these characteristics upon stimulated smooth muscle contraction was also captured well. Moreover, the related ultrastructural properties of the collagen-elastin network as well as the transmural cell distribution, were recordable at corresponding loading conditions by TPLSM. ConclusionThe presented multi-modal characterization platform enables comprehensive ex vivo measurements under well-controlled in vivo-like loading conditions, for in-depth studies focusing on arterial stiffening. Our findings emphasize the need for controlling dynamic pressure and axial stretch conditions in investigating mechanistic and constitutive aspects of arterial stiffening.

bioengineering↗

bioRxiv2024

The MAASWERP study: An international, comparative case study on measuring biomechanics of the aged murine aorta

Arterial stiffening is a hallmark of vascular ageing, and unravelling its underlying mechanisms has become a central theme in the field of cardiovascular disease. While various techniques and experimental setups are accessible for investigating biomechanics of blood vessels both in vivo and ex vivo, comparing findings across diverse methodologies is challenging. In the present study, we aimed to compare arterial stiffness measurements of two distinct ex vivo setups for measuring aortic mechanics. First, we measured arterial stiffness in the aorta of adult (5 months) and aged (24 months) wild-type C57Bl/6J mice in vivo, after which ex vivo biomechanical evaluation was performed using the Rodent Oscillatory Tension Setup to study Arterial Compliance (ROTSAC; University of Antwerp, Belgium) and the DynamX setup (Maastricht University, The Netherlands). Measurements in both setups were conducted in parallel with matched protocols and identical buffers and chemicals. Overall, both methods revealed age-related increased stiffness, although parameters of aortic mechanics showed different numerical values, suggesting that results are not directly interchangeable between methods. Surprisingly, smooth muscle cell contraction had opposing effects between the setups. Indeed, smooth muscle cell contraction increased arterial stiffness in the ROTSAC but decreased stiffness in the DynamX. These opposing effects could be attributed to how the two setups differentially load the collagen fibres in the arterial wall, ex vivo. In conclusion, the observed differences between the two ex vivo setups highlight the necessity to report findings on (altered) aortic mechanics in the context of the used methodology.

bioengineering↗

bioRxiv2023

Increased levels of circulating methylglyoxal have no consequence for cerebral microvascular integrity and cognitive function in young healthy mice

Diabetes and other age-related diseases are associated with an increased risk of cognitive impairment, but the underlying mechanisms remain poorly understood. Methylglyoxal (MGO), a by-product of glycolysis and a major precursor in the formation of advanced glycation end- products (AGEs), is increased in individuals with diabetes and other age-related diseases, and is associated with microvascular dysfunction. We now investigated whether increased levels of circulating MGO can lead to cerebral microvascular dysfunction, blood brain barrier (BBB) dysfunction, and cognitive impairment. Mice were supplemented or not with 50 mM MGO in drinking water for 13 weeks. Plasma and cortical MGO and MGO-derived AGEs were measured with UPLC-MS/MS. Peripheral and cerebral microvascular integrity and inflammation were investigated. Cerebral blood flow and neurovascular coupling were investigated with laser speckle contrast imaging, and cognitive tests were performed. We found a 2-fold increase in plasma MGO and an increase in MGO-derived AGEs in plasma and cortex. Increased plasma MGO did not lead to cerebral microvascular dysfunction, inflammation, nor cognitive decline. This study shows that increased concentrations of plasma MGO are not associated with cerebral microvascular dysfunction and cognitive impairment in healthy mice. Future research should focus on the role of endogenously formed MGO in cognitive impairment.

neuroscience↗