Biology subjects

Chan, Y.-H.

Publications and source records attributed to Chan, Y.-H..

5 recordsLinked to original sources

bioRxiv2025

Development and In Vivo Evaluation of a Novel Bioabsorbable Polylactic Acid Middle Ear Ventilation Tube

BackgroundOtitis media with effusion (OME) is a widespread condition causing hearing impairment, particularly in pediatric populations. Existing non-absorbable middle ear ventilation tubes frequently necessitate secondary surgical removal. Bioabsorbable polylactic acid (PLA) offers a promising alternative due to its inherent biocompatibility and tunable degradation characteristics. This study aimed to design, fabricate, and comprehensively evaluate a novel PLA middle ear ventilation tube. MethodsBioabsorbable PLA tubes were designed and fabricated based on commercial models. In vitro biocompatibility was assessed according to ISO 10993 guidelines. In vivo evaluations were performed in a guinea pig model, including otoscopic examinations, auditory brainstem response (ABR) measurements, micro-computed tomography (micro-CT) imaging, and histological analyses. ResultsThe PLA tubes were successfully designed and fabricated, exhibiting dimensions comparable to commercially available products. In vitro testing confirmed their biocompatibility. In vivo observations demonstrated that the PLA segments remained stable, with no significant inflammation detected. ABR measurements revealed no adverse impact on hearing function. Micro-CT imaging confirmed tube integrity and displayed initial signs of degradation over a 9-month period. Histological analyses indicated a favorable tissue response with minimal foreign body reaction. ConclusionThe developed PLA middle ear ventilation tube represents a highly promising alternative to conventional non-absorbable tubes. It demonstrates excellent biocompatibility, preserves auditory function, and exhibits a controlled degradation profile. This preclinical study provides strong support for further investigation and subsequent clinical trials to validate its safety and efficacy in human patients.

bioengineering↗

bioRxiv2024

Delineation of a thrombin receptor-stimulated vascular smooth muscle cell transition generating cells in the plaque-stabilising fibrous cap

AimsVascular smooth muscle cells (VSMCs) accumulate in atherosclerotic plaques and exhibit remarkable phenotypic plasticity, contributing to both plaque growth and stability. The plaque-stabilising fibrous cap is rich in VSMC-derived cells, yet the cellular transitions and regulatory mechanisms governing fibrous cap formation remain unclear. We aimed to delineate the VSMC phenotypic transitions associated with this critical process. Methods and ResultsMapping of lineage-traced VSMCs during plaque development revealed investment of VSMCs prior to fibrous cap formation. Using single-cell RNA-sequencing (scRNA-seq) profiles of lineage-traced VSMCs from atherosclerotic and acutely injured mouse arteries, we identified a disease-specific VSMC state co-expressing contractile genes with extracellular matrix (ECM) components (including fibrillar collagens and elastin) and NOTCH3, which are associated with fibrous cap formation. Computational trajectory analysis predicted that this proposed fibrous cap-related VSMC (fcVSMC) state arises from a previously described plastic, intermediate VSMC population expressing SCA1 and VCAM1. Clonal analysis further showed that NOTCH3+ fcVSMCs derive from intermediate VSMCs in both atherosclerosis and an acute vascular injury model, suggesting a conserved disease-relevant mechanism. The fcVSMCs were enriched in plaque fibrous caps compared to lesion cores, consistent with a role in fibrous cap formation. By combining scRNA-seq trajectory analysis and spatial transcriptomics of human atherosclerotic plaques, we identified protease-activated receptor-1 (PAR1) as a candidate regulator of fcVSMC generation. PAR1 was expressed by VSMCs in human plaque fibrous caps and, PAR1 activation by thrombin induced expression of contractile genes and ECM components associated with the fcVSMC state in human VSMCs. ConclusionsOur findings identify a VSMC transition linked to fibrous cap formation in atherosclerosis and show this is modelled by vascular injury. We identify VSMC-expressed PAR1 as a potential therapeutic target for promoting plaque stability by driving the transition to the matrix-producing, fibrous cap-associated VSMC state.

molecular biology↗

bioRxiv2022

Computer simulations reveal pathogenicity and inheritance modes of hearing loss-causing germinal variants

Variants in the gap junction beta-2 (GJB2) gene are the most common cause of hereditary hearing impairment. However, how GJB2 variants lead to local physicochemical and structural changes in the hexameric ion channels of connexin 26 (Cx26), resulting in hearing impairment, remains elusive. In the present study, using molecular dynamics (MD) simulations, we showed that detached inner-wall N-terminal "plugs" aggregated to reduce the channel ion flow in a highly prevalent V37I variant in humans. To examine the predictability of the computational platform, an artificial mutant, V37M, of which the effect was previously unknown in hearing loss, was created. Microsecond simulations showed that homomeric V37M Cx26 hemichannels had an abnormal affinity between the inner edge and N-termini to block the narrower side of the cone-shaped Cx26, while the most stable heteromeric channels did not. Consistent with these predictions, homozygous V37M transgenic mice exhibited apparent hearing loss, but not their heterozygous counterparts, indicating a recessive inheritance mode. Reduced channel conductivity was found in Gjb2V37M/V37M outer sulcus cells and Claudius cells but not in Gjb2WT/WT cells. We view that the current computational platform could serve as an assessment tool for the pathogenesis and inheritance of GJB2-related hearing impairments and other diseases caused by connexin dysfunction.

biophysics↗

bioRxiv2021

Data-driven analysis of COVID-19 reveals specific severity patterns distinct from the temporal immune response

Key immune signatures of SARS-CoV-2 infection may associate with either adverse immune reactions (severity) or simply an ongoing anti-viral response (temporality); how immune signatures contribute to severe manifestations and/or temporal progression of disease and whether longer disease duration correlates with severity remain unknown. Patient blood was comprehensively immunophenotyped via mass cytometry and multiplex cytokine arrays, leading to the identification of 327 basic subsets that were further stratified into more than 5000 immunotypes and correlated with 28 plasma cytokines. Low-density neutrophil abundance was closely correlated with hepatocyte growth factor levels, which in turn correlated with disease severity. Deep analysis also revealed additional players, namely conventional type 2 dendritic cells, natural killer T cells, plasmablasts and CD16+ monocytes, that can influence COVID-19 severity independent of temporal progression. Herein, we provide interactive network analysis and data visualization tools to facilitate data mining and hypothesis generation for elucidating COVID-19 pathogenesis.

immunology↗

bioRxiv2020

Toward the pathogenicity of the SLC26A4 p.C565Y variant using a genetically driven mouse model

Recessive variants of the SLC26A4 gene are a common cause of hearing impairment worldwide. In the past, cell lines and transgenic mice have been widely used to investigate the pathogenicity associated with the SLC26A4 variants. However, discrepancies in the pathogenicity between humans and cell lines or transgenic mice have been documented for some of the SLC26A4 variants. For instance, the p.C565Y variant, which has been reported to be pathogenic in humans, did not exhibit functional pathogenic consequences in cell lines. To address the pathogenicity of p.C565Y, we used a genotype-based approach in which we generated knock-in mice heterozygous (Slc26a4+/C565Y), homozygous (Slc26a4C565Y/C565Y), and compound heterozygous (Slc26a4919-2A>G/C565Y) for this variant. Subsequent phenotypic characterization revealed that mice segregating these genotypes demonstrated normal auditory and vestibular functions and normal inner ear morphology and expression of pendrin. These findings indicate that the p.C565Y variant is non-pathogenic for mice and that a single p.C565Y allele is sufficient to maintain normal inner ear physiology in mice. Our results highlight the differences in the pathogenicity associated with certain SLC26A4 variants between transgenic mice and humans, which should be taken into consideration while interpreting the results of animal studies for SLC26A4-related deafness.

genetics↗