Biology subjects

Versluis, M.

Publications and source records attributed to Versluis, M..

3 recordsLinked to original sources

bioRxiv2025

A human engineered mini-heart platform for mimicking ventricular pump function

Engineered cardiac tissue models for in vitro physiological studies often fail to replicate the pump function of the heart. Despite promising advancements, the use of engineered cardiac chambers is often hindered by complex fabrication processes and invasive characterization techniques. Here, we engineered a human cardiac chamber, referred to as a mini-heart, by employing a novel sacrificial molding approach within a customized bioreactor. The mini-hearts pumping capability was confirmed through optical recording of fluid displacement at the engineered tissue inlet, enabling the non-invasive acquisition of hemodynamic parameters such as stroke volume, stroke work, ejection fraction, and developed pressure. Morphological analysis of the engineered tissues revealed organized sarcomeres and extracellular matrix self-determination, highlighting the advantage of our degradable mold technology. Additionally, we have measured calcium transients during both spontaneous and electrically-paced beating, and observed a positive inotropic response to the {beta}-adrenergic agonist drug isoproterenol. Altogether, our biomimicking engineered tissue platform provides a robust tool for exploring cardiac pressure-volume dynamics, thereby facilitating complex disease modelling and drug screening applications in vitro.

bioengineering↗

bioRxiv2020

GABA quantification in human anterior cingulate cortex

{gamma}-Aminobutyric acid (GABA) is a primary inhibitory neurotransmitter in the human brain. It has been shown that altered GABA concentration plays an important role in a variety of psychiatric and neurological disorders. The main purpose of this study was to propose a combination of PRESS and MEGA-PRESS acquisitions for absolute GABA quantification and to compare GABA estimations obtained using total choline (tCho), total creatine (tCr), and total N-acetyl aspartate (tNAA) as the internal concentration references with water referenced quantification. The second aim was to demonstrate the fitting approach of MEGA-PRESS spectra with QuasarX algorithm using a basis set of GABA, glutamate, glutamine, and NAA in vitro spectra. Thirteen volunteers were scanned with the MEGA-PRESS sequence at 3T. Interleaved water referencing was used for quantification, B0 drift correction and to update the carrier frequency of RF pulses in real time. Reference metabolite concentrations were acquired using a PRESS sequence with short TE (30 ms) and long TR (5000 ms). Absolute concentration were corrected for cerebrospinal fluid, gray and white matter water fractions and relaxation effects. Water referenced GABA estimations were significantly higher compared to the values obtained by metabolite references. We conclude that QuasarX algorithm together with the basis set of in vitro spectra improves reliability of GABA+ fitting. The proposed GABA quantification method with PRESS and MEGA-PRESS acquisitions enables the utilization of tCho, tCr, and tNAA as internal concentration references. The use of different concentration references have a good potential to improve the reliability of GABA estimation.

neuroscience↗

bioRxiv2019

Quantification of DNA methylation using methylation-sensitive restriction enzymes and multiplex digital PCR

Epigenetic regulation is important in human health and disease, but the exact mechanisms remain largely enigmatic. DNA methylation represents one well-studied aspect of epigenetic regulation, but is challenging to quantify accurately. In this study, we introduce a digital approach for the absolute quantification of the amount, density and allele-specificity of DNA methylation. Combining the efficiency of methylation-sensitive restriction enzymes with the quantitative power of digital PCR, DNA methylation is measured accurately without the need to treat the DNA samples with sodium bisulphite. Moreover, as the combination of PCR amplicon and restriction enzyme is flexible, the context and density of DNA methylation can be taken into account. Additionally, by extending the experimental setup to a multiplex digital PCR, methylation markers may be analysed together with physically linked genetic markers to determine the allele-specificity of the methylation. In-silico simulations demonstrated the mathematical validity of the experimental setup. Next the approach was validated in a variety of healthy and malignant reference samples in the context of RASSF1A promotor methylation. RASSF1A is an established tumour suppressor gene, that is aberrantly methylated in many human cancers. A dilution series of well-characterized reference samples cross-validated the sensitivity and dynamic range of the approach. Compared to conventional PCR based methods, digital PCR provides a more accurate and more sensitive approach to quantify DNA methylation. As no sodium bisulphite conversion is needed, also analysis of minute amounts of DNA could be carried out efficiently.

genomics↗