Women's reproductive cessation is the earliest sign of human aging and is caused by decreasing oocyte quality. Similarly, C. elegans' reproduction declines in mid-adulthood and is caused by oocyte ...quality decline. Aberrant mitochondrial morphology is a hallmark of age-related dysfunction, but the role of mitochondrial morphology and dynamics in reproductive aging is unclear. We examined the requirements for mitochondrial fusion and fission in oocytes of both wild-type worms and the long-lived, long-reproducing insulin-like receptor mutant daf-2. We find that normal reproduction requires both fusion and fission, but that daf-2 mutants utilize a shift towards fission, but not fusion, to extend their reproductive span and oocyte health. daf-2 mutant oocytes' mitochondria are punctate (fissioned) and this morphology is primed for mitophagy, as loss of the mitophagy regulator PINK-1 shortens daf-2's reproductive span. daf-2 mutants maintain oocyte mitochondria quality with age at least in part through a shift toward punctate mitochondrial morphology and subsequent mitophagy. Supporting this model, Urolithin A, a metabolite that promotes mitophagy, extends reproductive span in wild-type mothers-even in mid-reproduction-by maintaining youthful oocytes with age. Our data suggest that promotion of mitophagy may be an effective strategy to maintain oocyte health with age.
We recently linked branched-chain amino acid transferase 1 (BCAT1) dysfunction with the movement disorder Parkinson's disease (PD), and found that RNAi-mediated knockdown of neuronal bcat-1 in C. ...elegans causes abnormal spasm-like 'curling' behavior with age. Here we report the development of a machine learning-based workflow and its application to the discovery of potentially new therapeutics for PD. In addition to simplifying quantification and maintaining a low data overhead, our simple segment-train-quantify platform enables fully automated scoring of image stills upon training of a convolutional neural network. We have trained a highly reliable neural network for the detection and classification of worm postures in order to carry out high-throughput curling analysis without the need for user intervention or post-inspection. In a proof-of-concept screen of 50 FDA-approved drugs, enasidenib, ethosuximide, metformin, and nitisinone were identified as candidates for potential late-in-life intervention in PD. These findings point to the utility of our high-throughput platform for automated scoring of worm postures and in particular, the discovery of potential candidate treatments for PD.
The inflammatory response in endothelial cells (ECs) leads to an increase in vascular permeability through the formation of gaps. However, the dynamic nature of vascular permeability and external ...factors involved is still elusive. In this work, we use a biomimetic blood vessel (BBV) microfluidic model to measure in real-time the change in permeability of the EC layer under culture in physiologically relevant flow conditions. This platform studies the dynamics and characterizes vascular permeability when the EC layer is triggered with an inflammatory agent using tracer molecules of three different sizes, and the results are compared to a transwell insert study. We also apply an analytical model to compare the permeability data from the different tracer molecules to understand the physiological and bio-transport significance of endothelial permeability based on the molecule of interest. A computational model of the BBV model is also built to understand the factors influencing transport of molecules of different sizes under flow. The endothelial monolayer cultured under flow in the BBV model was treated with thrombin, a serine protease that induces a rapid and reversible increase in endothelium permeability. On analysis of permeability data, it is found that the transport characteristics for fluorescein isothiocyanate (FITC) dye and FITC Dextran 4k Da molecules are similar in both BBV and transwell models, but FITC Dextran 70k Da molecules show increased permeability in the BBV model as convection flow (Peclet number > 1) influences the molecule transport in the BBV model. We also calculated from permeability data the relative increase in intercellular gap area during thrombin treatment for ECs in the BBV and transwell insert models to be between 12% and 15%. This relative increase was found to be within range of what we quantified from F-actin stained EC layer images. The work highlights the importance of incorporating flow in in vitro vascular models, especially in studies involving transport of large size objects such as antibodies, proteins, nano/micro particles, and cells.
Caenorhabditis elegans
is used as a model organism to study a wide range of topics in molecular and cellular biology. Conventional
C. elegans
assays often require a large sample size with frequent ...manipulations, rendering them labor-intensive. Automated high-throughput workflows may not be always the best solution to reduce benchwork labor, as they may introduce more complexity. Thus, most assays are carried out manually, where logging and digitizing experimental data can be as time-consuming as picking and scoring worms. Here we report the development of
Ce
Aid,
C. elegans
Application for inputting data, which significantly expedites the data entry process, utilizing swiping gestures and a voice recognition algorithm for logging data using a standard smartphone or Android device. This modular platform can also be adapted for a wide range of assays where recording data is laborious, even beyond worm research.
Nanodrug-carrier delivery in the blood stream is strongly influenced by nanoparticle (NP) dispersion. This paper presents a numerical study on NP transport and dispersion in red blood cell (RBC) ...suspensions under shear and channel flow conditions, utilizing an immersed boundary fluid-structure interaction model with a lattice Boltzmann fluid solver, an elastic cell membrane model and a particle motion model driven by both hydrodynamic loading and Brownian dynamics. The model can capture the multiphase features of the blood flow. Simulations were performed to obtain an empirical formula to predict NP dispersion rate for a range of shear rates and cell concentrations. NP dispersion rate predictions from the formula were then compared to observations from previous experimental and numerical studies. The proposed formula is shown to accurately predict the NP dispersion rate. The simulation results also confirm previous findings that the NP dispersion rate is strongly influenced by local disturbances in the flow due to RBC motion and deformation. The proposed formula provides an efficient method for estimating the NP dispersion rate in modeling NP transport in large-scale vascular networks without explicit RBC and NP models.
Isolating cells of interest from a heterogeneous population has been of critical importance in biological studies and clinical applications. In this study, a novel approach is proposed for utilizing ...an active ciliary system in microfluidic devices to separate particles based on their physical properties. In this approach, the bottom of the microchannel is covered with an equally spaced cilia array of various patterns which is actuated by an external stimuli. 3D simulations are carried out to study cilia-particle interaction and isolation dynamic in a microfluidic channel. It is observed that these elastic hair-like filaments can influence particle's trajectories differently depending on their biophysical properties. This modeling study utilizes immersed boundary method coupled with the lattice Boltzmann method. Soft particles and cilia are implemented through the spring connected network model and point-particle scheme, respectively. It is shown that cilia array with proper stimulation is able to continuously and non-destructively separate cells into subpopulations based on their size, shape, and stiffness. At the end, a design map for fabrication of a programmable microfluidic device capable of isolating various subpopulations of cells is developed. This biocompatible, label-free design can separate cells/soft microparticles with high throughput which can greatly complement existing separation technologies.
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