Biology subjects

Yam, S. L. S.

Publications and source records attributed to Yam, S. L. S..

3 recordsLinked to original sources

bioRxiv2026

Feasibility of adopting water displacement and 3D scanning methods to quantify lung volume reduction in ex vivo models

Lung volume reduction is a treatment for chronic obstructive pulmonary disease (COPD) patients with severe emphysema. Currently, in vivo animal models are used as a first step to quantify the efficiency of novel lung volume reduction treatments. By quantifying lung volume reduction in ex vivo samples, animal testing may be reduced. This study proposes two new methods for quantifying lung volume reduction in ex vivo tissue: water displacement and three-dimensional (3D) scanning. Porcine lung lobes were inflated and treated with cyanoacrylate glue to simulate lung volume reduction. Volume changes were measured using a custom water displacement setup and in a ventilated setting using a handheld Artec Space Spider 3D surface scanner. Both techniques detected post-treatment volume reductions. Water displacement offers a simple, cost-effective approach for isolated lung lobes, while 3D scanning enables volumetric analysis of intact lungs under ventilated conditions. These methods provide a reliable intermediate step between in vitro and in vivo testing, reducing animal use and improving preclinical assessment of novel lung volume altering interventions.

bioengineering↗

bioRxiv2025

Photodegradable Hydrogels for On-Demand Modeling of Age-Related Spatiotemporal ECM Deformation

The extracellular matrix (ECM) plays a crucial role in regulating tissue behavior through a dynamic interplay of spatial and temporal cues. Dynamic materials capable of modulating these cues at relevant scales are essential for tackling current challenges in tissue engineering and addressing fundamental biological questions. In vision research, there is a notable lack of suitable in vitro systems to study ECM dynamics. To help fill this gap, we developed an easy-to-use, photosensitive poly(ethylene glycol)-based hydrogel that can deform on demand to simulate ECM bulging, known as drusen, associated with the aging of the outer retina. Our findings demonstrate that variations in the size of these artificial drusen during culture impact morphometric parameters of the retinal pigment epithelium, offering new insights into its mechanical resilience to different drusen sizes. Notably, drusen formation in our system does not significantly affect the cellular actin cytoskeleton or polarity, which are often disrupted in conventional acute substrate deformation models, allowing the study of early aging before detectable pathology. In summary, we present a light-tunable hydrogel platform that enables precise spatial mimicry of ECM topographical changes, offering a promising tool for investigating the mechanobiological aspects of dynamic cell-matrix interactions.

bioengineering↗

bioRxiv2025

Age-associated Tissue Organisation Shifts Retinal Pigment Epithelium Actomyosin Plasticity in Phagocytosis

Tissue homeostasis relies on mechanical feedback loops balanced by cell loss and proliferation. However, maintaining this balance becomes particularly challenging in postmitotic tissues, where alternative mechanisms replace compensatory proliferation. In the postmitotic retinal pigment epithelium (RPE), these mechanisms include significant structural adaptations over time. Yet, how these adaptations relate to epithelial mechanical homeostasis and age-associated functional decline remains poorly understood. To establish the relationship between structural changes, mechanical homeostasis and function, we developed an in vitro reductionistic model mimicking age-related reduction in RPE cell density. Inducing large-scale apoptosis in postmitotic stem cell-derived RPE monolayers recapitulates structural hallmarks of aged tissue, such as reduced cell height, shortened microvilli and cytoskeletal reorganisation. This new structure acquires a new mechanical equilibrium, evidenced by tissue stiffening and enhanced junctional contractility. Functionally, the monolayers display impaired vision-supporting phagocytosis of photoreceptor outer segments. Mechanistically, modulation of actin nucleators, Arp2/3 and formins, demonstrates that apicolateral monolayer deformation is critical for phagocytosis and may be compromised in aged RPE. Our findings suggest that a shift in mechanical homeostasis due to cell loss is a major driver of age-related RPE functional decline. Importantly, we show that structural remodelling in ageing alone can compromise tissue function, independent of other stressors.

cell biology↗