Biology subjects

Fromen, C. A.

Publications and source records attributed to Fromen, C. A..

4 recordsLinked to original sources

bioRxiv2026

Particle Phagocytosis Amplifies Secretion of Small Extracellular Vesicles in Macrophages

Macrophage-derived extracellular vesicles (EVs) are critical mediators of immune communication and tissue homeostasis, yet the exogenous factors that regulate their release and composition remain poorly defined. Here, we identify phagocytosis of particulate materials as a direct and general driver of macrophage small EV production through a lysosome-linked mechanism. Across primary and engineered murine and human macrophage cultures, phagocytic uptake robustly increased small EV secretion, an effect that was recapitulated in vivo following orotracheal instillation that resulted in elevated small EV abundance in bronchoalveolar lavage fluid. This phagocytosis-driven small EV amplification depended on particle size (hydrodynamic diameter >200 nm) and residence time within the phagolysosome. Electron microscopy and proteomic analyses revealed increased multivesicular body formation following particle uptake, establishing a mechanistic link between phagocytosis and small EV biogenesis. Notably, this pathway regulated both protein and particulate cargo in secreted macrophage small EVs. Together, these findings expand the canonical framework of macrophage EV biogenesis to include phagocytosis-driven regulation and establish a single step process for controlling small EV production and cargo loading, with implications for understanding particulate exposures and for developing macrophage- and EV-based immunotherapies.

bioengineering↗

bioRxiv2025

Probing Critical Injury Thresholds for Maladaptive Epithelial Injury and Repair Processes with Photoresponsive Bioinspired Synthetic Basement Membrane

Microinjuries to the lung epithelium are hypothesized to initiate maladaptive processes that lead to fibrosis. Human in vitro models remain a great need for studying this injury-initiation process for mechanistic understanding and therapeutic development. We established a photoresponsive synthetic extracellular matrix (ECM) inspired by the basement membrane that enables triggered injuries of defined size and frequency for probing cellular responses. The synthetic matrix integrated a photolabile bis-coumarin linker for light-triggered injury and relevant integrin-binding peptides for cell function. Bio-orthogonal chemistry was used to create hydrogel-based ECMs with tunable elasticity in transwells, which are traditionally used for epithelial cell culture. Integrin-binding peptide combinations synergistically promoted model epithelial cell layer formation with increased E-cadherin expression and barrier function. An accessible photomasking approach was established for selectively photodegrading the synthetic matrix with cytocompatible visible light and achieving different injury depths and widths. Following a critical injury size, cell responses recapitulated key features of dysregulated re-epithelialization with decreased E-cadherin, proliferation, and barrier function and increased apoptosis. This work provides a new materials-based tool for probing injury and repair processes with tunable control of both the ECM and injury to it with opportunities for future mechanistic and therapeutic insights to address maladaptive wound healing processes.

bioengineering↗

bioRxiv2021

Computational Modeling of Aerosol Particle Transport through Lung Mucosa

Delivery of aerosols to the lung has great potential for the treatment of various lung diseases. However, the lungs are coated by a protective mucus layer whose complex properties make this form of delivery difficult. Mucus is a non-Newtonian fluid and is cleared from the lungs over time by ciliated cells. Further, its gel-like structure hinders the diffusion of particles through it. Any aerosolized treatment of lung diseases must have certain properties to circumvent the mucosal barrier, and these properties may vary between diseases, drugs, and patients. Using computational fluid dynamics, a model of this mucus layer was constructed to simulate the convective and diffusive transport of impacted aerosol particles. The model predicts the dosage fraction of particles of a certain size that penetrate the mucus and reach the underlying tissue, as well as the distance downstream of the dosage site where epithelial concentration is maximized. Reactions that may occur in solution are also considered, with simulated data for the interaction of a model virus and antibody. The model is modular so that various lung regions and patient health states may be simulated.

bioengineering↗

bioRxiv2021

Nanoparticle Internalization Promotes the Survival of Primary Macrophages

Macrophages, a class of tissue resident innate immune cells, are responsible for sequestering foreign objects through the process of phagocytosis, making them a promising target for immune-modulation via particulate engineering. Here, we report that nanoparticle (NP) dosing and cellular internalization via phagocytosis significantly enhances survival of ex vivo cultures of primary bone marrow-derived, alveolar, and peritoneal macrophages over particle-free controls. The enhanced survival is attributed to suppression of caspase-dependent apoptosis and is linked to phagocytosis and lysosomal signaling, which was also found to occur in vivo. Uniquely, poly(ethylene glycol)-based NP treatment does not alter macrophage polarization or lead to inflammatory effects. The enhanced survival phenomenon is also applicable to NPs of alternative chemistries, indicating the potential universality of this phenomenon with relevant drug delivery particles. These findings provide a framework for extending the lifespan of primary macrophages ex vivo for drug screening, vaccine studies, and cell therapies and has implications for any in vivo particulate immune-engineering applications.

bioengineering↗