High-throughput extraction on a dynamic solid phase for low-abundance biomarker isolation from biological samples.

Liquid biopsy, in particular circulating tumor DNA (ctDNA) analysis, has paved the way for a new noninvasive approach to cancer diagnosis, treatment selection and follow-up. As a crucial step in the analysis, the extraction of the genetic material from a complex matrix needs to meet specific requirements such as high specificity and low loss of target. Here, we developed a new generation of microfluidic fluidized beds (FBs) that enable the efficient extraction and preconcentration of specific ctDNA sequences from human serum with flow rates up to 15 µL/min. We first demonstrated that implementation of a vibration system inducing flow rate fluctuations combined with a mixture of different bead sizes significantly enhanced bead homogeneity, thereby increasing capture efficiency. Taking advantage of this new generation of high-throughput magnetic FBs, we then developed a new method to selectively capture a double-stranded (dsDNA) BRAF mutated DNA sequence in complex matrices such as patient serum. Finally, as proof of concept, ligation chain reaction (LCR) assays were performed to specifically amplify a mutated BRAF sequence, allowing the detection of concentrations as low as 6 × 104 copies/µL of the mutated DNA sequence in serum.

Construction of a Multitubular Perfusable Kidney-on-Chip for the Study of Renal Diseases.

The organ-on-chip model offers versatility and modularity of in vitro models while approaching the biological fidelity of in vivo models. We propose a method to build a perfusable kidney-on-chip aiming at reproducing key features of the densely packed segments of nephrons in vitro; such as their geometry, their extracellular matrix, and their mechanical properties. The core of the chip is made of parallel tubular channels molded into collagen I that are as small as 80 µm in diameter and as close as 100 µm apart. These channels can further be coated with basement membrane components and seeded by perfusion of a suspension of cells originating from a given segment of the nephron. We optimized the design of our microfluidic device to achieve high reproducibility regarding the seeding density of the channels and high fluidic control of the channels. This chip was designed as a versatile tool to study nephropathies in general, contributing to building ever better in vitro models. It could be particularly interesting for pathologies such as polycystic kidney diseases where mechanotransduction of the cells and their interaction with adjacent extracellular matrix and nephrons may play a key role.

Correction to 'Mathematical modelling of oxygen transport in a muscle-on-chip device' (2022) by Hardman et al.

[This corrects the article DOI: 10.1098/rsfs.2022.0020.][This corrects the article DOI: 10.1098/rsfs.2022.0020.].

Mathematical modelling of oxygen transport in a muscle-on-chip device.

Muscle-on-chip devices aim to recapitulate the physiological characteristics of in vivo muscle tissue and so maintaining levels of oxygen transported to cells is essential for cell survival and for providing the normoxic conditions experienced in vivo. We use finite-element method numerical modelling to describe oxygen transport and reaction in a proposed three-dimensional muscle-on-chip bioreactor with embedded channels for muscle cells and growth medium. We determine the feasibility of ensuring adequate oxygen for muscle cell survival in a device sealed from external oxygen sources and perfused via medium channels. We investigate the effects of varying elements of the bioreactor design on oxygen transport to optimize muscle tissue yield and maintain normoxic conditions. Successful co-culturing of muscle cells with motor neurons can boost muscle tissue function and so we estimate the maximum density of seeded neurons supported by oxygen concentrations within the bioreactor. We show that an enclosed bioreactor can provide sufficient oxygen for muscle cell survival and growth. We define a more efficient arrangement of muscle and perfusion chambers that can sustain a predicted 50% increase in maximum muscle volume per perfusion vessel. A study of simulated bioreactors provides functions for predicting bioreactor designs with normoxic conditions for any size of perfusion vessel, muscle chamber and distance between chambers.