Biology subjects

Leung, B. M.

Publications and source records attributed to Leung, B. M..

5 recordsLinked to original sources

bioRxiv2025

Metal Ion-Releasing Glass Particles to Enhance Antibiotic Efficacy Against Cystic Fibrosis Infection

Cystic fibrosis is characterized by thickened airway mucus that impairs mucociliary clearance and promotes persistent bacterial infections. These chronic infections, primarily caused by Pseudomonas aeruginosa and Staphylococcus aureus, lead to progressive lung damage and respiratory failure, which are the leading causes of mortality in cystic fibrosis patients. Although antibiotics remain the cornerstone of treatment for such airway infections, incomplete bacterial eradication often contributes to the emergence of antibiotic resistance. This study explores whether the efficacy of conventional antibiotics can be enhanced through co-delivery with antibacterial metal ions released from borate-based bioactive glasses. To evaluate this combination therapy, we developed an in vitro airway infection model that replicates key features of the cystic fibrosis airway environment. The model incorporates a layer of bronchial epithelial cells, a mucus-like hydrogel, and bacteria deposited using an aqueous two-phase system. Multiple bioactive glass formulations were evaluated for their ability to augment antibiotic activity and enhance bacterial eradication. The results demonstrated additive or synergistic antibacterial effects against P. aeruginosa and S. aureus, while maintaining mammalian cell viability. These findings suggest that metal ion-antibiotic combination therapies delivered via bioactive glasses may improve treatment outcomes for cystic fibrosis-related infections and reduce reliance on high-dose or prolonged antibiotic regimens. Such approaches hold promise not only for cystic fibrosis patients but also for broader clinical applications where antibiotic resistance is a growing concern.

bioengineering↗

bioRxiv2025

Chitosan-Polyphosphate Scaffold Loaded with Copper for Endodontic Regeneration: A Laboratory Study

ObjectiveRegenerative endodontics procedures show promise in treating immature teeth with necrotic pulp and apical periodontitis. This procedure involves the replacement of damaged and infected pulp tissue with viable tissue that restores the normal tooth structure and function. Antimicrobials are currently used to control the infection; however, they are cytotoxic to stem cells of the apical papilla (SCAP) and can lead to root canal calcification. Management of these teeth requires a scaffold that can control root canal infection, wick the blood into the canal, and support the viability and differentiation of SCAP while inhibiting intracanal calcification. This study aims to develop a composite scaffold made of polyphosphate, a calcium binding inorganic polymer shown to promote cell proliferation and tissue regeneration, chitosan, a natural antimicrobial polymer that supports stem cell viability and activity, and copper, a metal ion with bactericidal properties. MethodologyThe scaffold was prepared by adding copper (Cu) to chitosan solution, followed by polyphosphate. The resulting scaffold was then freeze-dried and analyzed for elemental composition, chemical structure, release of Cu, antibacterial properties, cytotoxicity, as well as differentiation and mineralization assays. Data were analysed by a two-way analysis of variance (ANOVA) followed by the Tukey post hoc test. ResultThis study demonstrates that, by combining polyphosphate and chitosan, we could fabricate a scaffold that inhibits bacterial growth by 40 % and supports the viability of fibroblast and SCAP. Adding copper to this scaffold further increased bacterial growth inhibition by up to 68% while preserving cell viability. The immunocytochemistry and Alizarin Red staining revealed that this scaffold also supports the odontogenic differentiation of these stem cells while inhibiting their mineralization potential. Furthermore, this scaffold can be fabricated as a 3D cone-shaped scaffold with a strong vertical wicking ability at a rate of 0.5 mm/s and excellent degradability, with 53 % of the scaffold degraded after 28 days. ConclusionsThis study shows that a copper-loaded chitosan-polyphosphate scaffold combines biocompatibility, antibacterial activity, wicking ability, and biodegradability and has great potential as an endodontic regenerative scaffold.

bioengineering↗

bioRxiv2025

Stable and assayable polymicrobial human airway model reveals complex interactions between Pseudomonas aeruginosa and lung commensals

Polymicrobial-host crosstalk shapes airway barrier integrity and inflammation, yet standard in vitro systems rarely sustain interaction-dependent phenotypes. We engineered an aqueous two-phase system (ATPS) confined bronchial co-culture that stabilized day-scale assays while maintaining epithelial function. A 16HBE14o-/HUVEC cell insert model was challenged with Pseudomonas aeruginosa PA01, Streptococcus pneumoniae D39, and the commensals Rothia mucilaginosa and Lactobacillus casei in mono- and polymicrobial combinations. We evaluated epithelium permeability to FITC-dextran, cell junction integrity, bacterial-induced cytotoxicity, IL-6 and IL-8 release and bacterial viability. ATPS preserved a workable assay window and bacterial confinement over 24h. PA01 disrupted barrier integrity, and commensals mitigated this pathogenic effect, whereas PA01 co-cultured with S. pneumoniae exhibited synergistic damage effects on the lung epithelium. Junctional imaging corroborated functional readouts, and cytotoxicity remained low across conditions. Cytokine shifts were condition-specific but modest, demonstrating compatibility for soluble mediator profiling. We generated a human airway-microbiome model in which ATPS confinement enabled modelling of dynamic lung-microbiome interactions, reproducing known P. aeruginosa pathogenic effects and commensal protection of the epithelium.

microbiology↗

bioRxiv2023

Modeling Cystic Fibrosis Chronic Infection Using Engineered Mucus-like Hydrogels

The airway mucus of patients with cystic fibrosis has altered properties which create a microenvironment primed for chronic infections that are difficult to treat. These complex polymicrobial airway infections and corresponding mammalian-microbe interactions are challenging to model in vitro. Here, we report the development of mucus-like hydrogels with varied compositions and viscoelastic properties reflecting differences between healthy and cystic fibrosis airway mucus. Models of cystic fibrosis and healthy airway microenvironments were created by combining the hydrogels with relevant pathogens, human bronchial epithelial cells, and an antibiotic. Notably, pathogen antibiotic resistance was not solely dependent on the altered properties of the mucus-like hydrogels but was also influenced by culture conditions including microbe species, monomicrobial or polymicrobial culture, and the presence of epithelial cells. Additionally, the cystic fibrosis airway model showed the ability to mimic features characteristic of chronic cystic fibrosis airway infections including sustained polymicrobial growth and increased antibiotic tolerance.

bioengineering↗

bioRxiv2022

Tumor Spheroids Layered in an Imageable Cancer Environment (T-SLICE): a novel in vitro platform to study tumor biology

Cancer treatment is shifting towards precise medicine informed by tumor genetics and structural features. In recent years, it has become increasingly recognized that patient tumors--even those of the same tissue origin--can differ substantially between patients and respond differently to treatment. Given this, it is necessary to design therapies that target the heterogeneity of tumors. When investigating novel therapeutics in the laboratory, conventional cell culture models do not adequately recapitulate this heterogeneity and therefore may not accurately represent drug responses. Recent advances in miniaturized organ-on-a-chip models have been able to generate more complex microenvironments for in vitro studies. However, many of these models do not resemble the scale of clinically relevant tumors and pose a high barrier to use because they are technically complex. To facilitate mechanistic studies of the tumor microenvironment (TME), we designed T-SLICE, a chip made using commercially available elastomers and designed to fit in a standard 6-well plate. This simple 3-D tumor model incorporates microfluidic principles into a fully customizable TME, wherein cells drive the formation of biochemical gradients akin to those observed within a real tumor. In T-SLICE, spheroids are seeded atop a monolayer of fibroblasts situated between two closely spaced coverslips (300-700 {micro}m). The restrictive gap height limits the permeation of oxygen (O2) and hinders the removal of carbon dioxide (CO2) and metabolic waste, which leads to the generation of tumor-like hypoxic gradients. We demonstrate that T-SLICE establishes cell-driven oxygen gradients leading to the formation of a hypoxic core, with further impacts on cellular viability, mitochondrial membrane potential (MMP), and proliferation. T-SLICE cultures can be imaged live or fixed and stained for immunohistochemistry (IHC). These features of T-SLICE make it an accessible and faithful model of a tumors heterogeneity and open the possibility for more faithful testing of novel therapeutics in the context of a realistic TME.

bioengineering↗