Biology subjects

Bu, A.

Publications and source records attributed to Bu, A..

3 recordsLinked to original sources

bioRxiv2025

Limb-on-a-Chip: An All-Hydrogel Platform for Scalable and Reproducible Engineering of Neuromuscular Tissues

Diseases or injuries that impact neuromuscular tissues have a severe negative impact on human health, mobility, and quality-of-life, motivating the development of tissue engineered in vitro models of the motor control system. Current neuromuscular organoids and organ-on-a-chip platforms either rely on stochastic self-assembly that limits reproducibility or require complex microfabrication processes that preclude high-resolution imaging and scalable functional analysis. We have developed a Limb-on-a-Chip platform that addresses key challenges of current model systems by enabling reproducible and scalable manufacturing of neuromuscular tissues compartmentalized into "spinal cord" and "limb" chambers, while promoting biochemical crosstalk between cell types. Our fabrication method leverages 3D printed molds to perform 1-step micropatterning of an all-hydrogel chip containing precise features to guide muscle fiber alignment and motor neuron axonal outgrowth. We demonstrate the ability to co-culture motor neurons and skeletal muscles within this hydrogel platform, enabling tissue-wide readouts of muscle force as well as single cell-resolution measurements of muscle fiber calcium activity. Our accessible method for fabricating reproducible in vitro neuromuscular models that are compatible with high-resolution imaging and functional readouts provides a powerful new tool for investigating the neuromuscular interface in health and disease.

bioengineering↗

bioRxiv2025

Physiological and functional characterization for high-throughput optogenetic skeletal muscle exercise assays

Exercise has long been considered an essential part of human health and longevity. Recent physiological studies have expanded muscles role beyond simply acting as an actuator, revealing muscles exercise-mediated paracrine and endocrine relationships with other organ systems. In vitro engineered skeletal muscle models can address physiological questions about exercise adaptation with the precision of cell biology. Optogenetic tools have enabled a noninvasive approach to stimulating muscle contraction that avoids the potential off-target effects of electrical stimulation techniques. In this article we propose high-throughput culture and optical exercise protocols to generate statistically robust cellular exercise response datasets. We characterize optical rheobase for 2D muscle tissue morphology, finding that optical intensities as low as 5 W mm-2 can trigger contraction. We then analyze bulk RNA sequencing data collected from high throughput, acute exercise protocols and find a rich display of transcriptional behavior that is consistent with experimental observations. The spontaneous contractility of our tissue constructs introduced oxygen diffusion challenges when maintained in a 24 well plate, and our analysis shows divergent myogenic and pathological transcriptional consequences of hypoxia. We believe our techniques provide a practical foundation for conducting future high-precision in vitro exercise studies of skeletal muscle. Translational impactHigh-fidelity, engineered skeletal muscle has potential to elucidate exercise-mediated response pathways at the cell and tissue level. We leverage optogenetic techniques to develop a high-throughput assay that optically stimulates 2D muscle monolayers, avoiding potential cell damage from electrical stimulation. Our culture and exercise protocol generates statistically robust RNA sequencing datasets which reveal myogenic and pathological responses to exercise and in vitro culture conditions, informing practical next steps to cultivate stronger, more physiologically relevant muscle models.

bioengineering↗

bioRxiv2024

2.5D Actuating Substrates Enable Decoupling the Mechanical and Biochemical Effects of Muscle Exercise on Motor Neurons

Emerging in vivo evidence suggests that exercise impacts peripheral nerves, but the difficulty of isolating and studying the muscle-specific impact on motor neurons in vivo, as well as the inability to decouple the biochemical and mechanical impacts of exercise in this setting, motivate investigating this phenomenon in vitro. In this study, we show that tuning the mechanical properties of fibrin hydrogels can generate stable 2.5D motor neuron and contractile skeletal muscle cultures that enable long-term efficient secretome harvesting from exercised tissues. Motor neurons stimulated with muscle-secreted cytokines significantly upregulate neurite outgrowth and migration, with an effect size dependent on exercise intensity. Actuating magnetic microparticles embedded within 2.5D substrates enabled us to dynamically stretch motor neurons and non-invasively mimic the mechanical effects of exercise, revealing that dynamic stretch has an equally significant impact on axonogenesis. RNA sequencing revealed different transcriptomic signatures between groups, with biochemical stimulation having a significantly greater impact on cell signaling related to axon growth and development, neuron projection guidance, and neuron-muscle synapse maturation. Our study thus leverages 2.5D actuating substrates to robustly validate a hypothesized role for muscle exercise in regulating motor neuron growth and maturation through both mechanical and biochemical signaling.

bioengineering↗