Biology subjects

Haag, P.

Publications and source records attributed to Haag, P..

4 recordsLinked to original sources

bioRxiv2025

LoAR-Exo and HiAR-Exo: One-step label-free isolation of extracellular vesicles using inertial microfluidic devices

Extracellular vesicles (EVs) are lipid membrane-bound nanoscale (20 nm - 1000 nm) objects shed by all cells. As EVs play an important role in intercellular signaling, these have emerged as promising biomarkers for many diseases including cancer and neurodegenerative disorders. A major bottleneck in research into EVs and their smooth translation to clinic as disease biomarkers is a lack of access to affordable and user-friendly technologies to quickly isolate EVs from complex biological and clinical samples with acceptable purity and yield. Here, we report two different designs of inertial microfluidic devices (e.g. LoAR-Exo and HiAR-Exo) that can isolate EVs from different kinds of biological samples in a single label-free step using a spiral microchannel design with different aspect ratios. LoAR-Exo has a height-to-width aspect ratio [~] 1, while HiAR-Exo has a height-to-width aspect ratio of 2.5, optimized by COMSOL simulations. We tested both designs by separating polystyrene particles of size < 1 m from a heterogeneous mixture. We then benchmarked the performance of the microfluidic chips against ultracentrifugation and a precipitation kit by isolating EVs from the cell culture-conditioned media (CCM) of MDA-MB-231 cells. We also compared the microchip with SEC by using the CCM from H1975/OR cells. The size distribution of EVs isolated by the microfluidic chip was comparable with ultracentrifugation, precipitation and SEC. In summary, both devices isolated EVs from as little as 1 mL of sample volume using a label-free technique in a continuous manner and without any user intervention. Both microfluidic platforms offer a simple, efficient, and scalable alternative to conventional methods for EV isolation.

bioengineering↗

bioRxiv2022

Analyses of single extracellular vesicles from non-small lung cancer cells to reveal effects by Epidermal growth factor inhibitor treatments

Precision cancer medicine have changed the treatment landscape of non-small cell lung cancer (NSCLC) as illustrated by tyrosine kinase inhibitors (TKIs) towards mutated Epidermal growth factor receptor (EGFR). Yet, responses to such TKIs e.g., erlotinib and osimertinib among patients are heterogenous and there is a need for non-invasive blood-based analytics to follow treatment response and reveal resistance to improve patients treatment outcome. Recently, extracellular vesicles (EVs) have been identified as an important source of tumor biomarkers promising to revolutionize liquid biopsy-based diagnosis of cancer. However, high heterogeneity has been a major bottleneck. The pathological signature is often hidden in the differential expression of membrane proteins in a subset of EVs which are difficult to identify with bulk techniques. Using a fluorescence-based approach, we for the first time demonstrate that the single-EV technique can be used to monitor the treatment response of targeted cancer therapies such as TKIs towards EGFR. To test the hypothesis, we analyzed the membrane proteins of native EVs extracted from EGFR-mutant NSCLC cell line, both prior and post treatment with EGFR-TKIs erlotinib or osimertinib. The selected cell line being refractory to erlotinib and responsive to osimertinib makes it a suitable model system. The expression level of five surface proteins; two common tetraspanins (CD9, CD81) and three markers of specific interest in lung cancer (EGFR, PD-L1, HER2) were studied. The data suggest that in contrast to erlotinib, the osimertinib treatment increases the population of PD-L1, EGFR and HER2 positive EVs while the expression level per EV decreases for all the three markers. The PD-L1 and HER2 expressing EV population seems to increase by several fold because of osimertinib treatment. The observations agree with the previous reports performed on cellular level indicating the biomarker potential of EVs for liquid-biopsy based monitoring of targeted cancer treatments. HighlightsO_LIMembrane protein analyses of single EVs may reveal distinct differences when lung cancer cells are refractory vs responsive under different EGFR-TKI treatments. C_LIO_LIComparison of 1st generation erlotinib and 3rd generation osimertinib shows clear signature on the expression of PD-L1, EGFR, HER2 on single EVs C_LIO_LIColocalization showed a change in common marker combinations before after treatment. C_LIO_LIPD-L1 expression per vesicle decreases while the number of PD-L1 positive EVs increases as a result of osimertinib treatment, indicating that such signature may not be detectable under bulk analysis C_LI

bioengineering↗

bioRxiv2022

Microchip-based electrokinetic biosensor: microfabrication and application in membrane protein profiling of extracellular vesicles

Detection of analyte using streaming current has been previously explored using both experimental and theoretical approaches. However, little has been done to develop a viable microchip which can be exploited to deliver a sensitive, robust, and scalable biosensor device. In this study, we demonstrate the fabrication of such a device on silicon wafer using a scalable silicon microfabrication technology followed by their characterization and optimization for highly sensitive detection of small extracellular vesicles (sEVs). We show that the sensitivity of the devices, estimated using a common protein-ligand pair and sEVs significantly outperforms previous reports using the same principle. Two versions of the microchips, denoted as enclosed and open-top microchip, were developed and compared aiming to discern the importance of high-pressure measurement vs easier and better surface preparation capacity. A custom-built chip-manifold allowing easy interfacing with standard microfluidic connections was also developed. By investigating different electrical, fluidic, morphological, and fluorescence measurements, we show that while the enclosed microchip with its robust glass-silicon bonding can withstand higher pressure and thus generate higher streaming current, the open-top configuration offers several practical benefits including easy surface preparation, uniform probe conjugation, and improvement in the limit of detection (LoD). We further compare two common surface functionalization strategies and show that the proposed microchip can achieve both high sensitivity for membrane protein profiling and low LoD for sEV detection. At the optimum condition, we demonstrate that the microchip can detect sEVs reaching a LoD of 104 sEV/mL, which is among the lowest in the reported microchip-based methods.

bioengineering↗

bioRxiv2021

High throughput imaging of nanoscale extracellular vesicles by scanning electron microscopy for accurate size-based profiling and morphological analysis.

Nanoscale extracellular vesicle (EVs) have been found to play a key role in intercellular communication, offering opportunities for both diagnostics and therapeutics. However, lying below the diffraction limit and also being highly heterogeneous in their size, morphology and abundance, these vesicles pose significant challenges for their physical characterization. Here, we present a direct visual approach for their accurate morphological and size-based profiling by using scanning electron microscopy (SEM). To achieve that, we methodically examined various process steps and developed a protocol to improve the throughput, conformity and image quality while preserving the shape of EVs. The investigation was performed with small EVs (sEVs) isolated from a non-small cell lung cancer (NSCLC) cell line H1975 as well as from a human serum, and the results were compared with those obtained from nanoparticle tracking analysis (NTA). While the comparison of the sEV size distributions showed good agreement between the two methods for large sEVs (diameter >70 nm), the microscopy based approach showed a better capacity for analyses on smaller vesicles, with higher sEV counts compared to NTA. In addition, we demonstrated the possibility of identifying non-EV particles based on size and morphological features. The study also showed process steps that can generate artifacts bearing resemblance with sEVs. The results therefore present a simple way to use a widely available microscopy tool for accurate and high throughput physical characterization of EVs.

bioengineering↗