Biology subjects

Man, K.

Publications and source records attributed to Man, K..

3 recordsLinked to original sources

bioRxiv2022

Biomimetic human lung alveolar interstitium chip with extended longevity

Determining the mechanistic causes of lung diseases, developing new treatments thereof, and assessing toxicity whether from chemical exposures or engineered nanomaterials would benefit significantly from a preclinical human lung alveolar interstitium model of physiological relevance. The existing preclinical models have limitations because they fail to replicate the key anatomical and physiological characteristics of human alveoli. Thus, a human lung alveolar interstitium chip was developed to imitate key alveolar microenvironmental factors including: an electrospun nanofibrous membrane as the analogue of the basement membrane for co-culture of epithelial cells with fibroblasts embedded in 3D collagenous gels; physiologically relevant interstitial matrix stiffness; interstitial fluid flow; and 3D breathing-like mechanical stretch. The biomimetic chip substantially improved epithelial barrier function compared to transwell models. Moreover, the chip having a gel made of a collagen I-fibrin blend as the interstitial matrix sustained the interstitium integrity and further enhanced the epithelial barrier resulting in a longevity that extended beyond eight weeks. The assessment of multiwalled carbon nanotube toxicity on the chip was in line with the animal study.

bioengineering↗

bioRxiv2022

Understanding Vascular Endothelial Cell Behavior Using a Mechanical Strain Gradient Generated by an Electromagnetic Stretching Device

Cardiovascular diseases cause an estimated 17.9 million deaths globally each year (World Health Organization). Endothelial cells that line the vasculature and the endocardium are subjected to cyclic mechanical stretch. Deviation from physiological stretch can alter the endothelial function, having the risk of atherosclerosis and myocardial infarction. To understand the mechanical stretch effects, cell culture platforms that provide mechanical stretch have been developed. However, most of them have fixed strain and frequency, sometime not in the pathophysiological range. We thus developed a novel, electromagnetically driven, uniaxial stretching device, where cells were grown on a flexible polydimethylsiloxane (PDMS) membrane mounted onto a 3-D printed track. The strain of the membrane was readily controlled by tailoring the track design and the frequency was determined by electromagnetic actuation. Furthermore, the mechanical strain gradient was generated on a PDMS membrane with a tapered thickness. This strain gradient, ranging from 1.5% to 40%, covered both physiological and pathological vascular stretch ranges. When human vascular endothelial cells were subjected to the cyclic stretch, the cells exhibited strain-dependent cell and nuclear orientation and elongation perpendicular to the stretching direction, compared to the random cell and nuclear orientation under the static condition. However, the overstretching led to deviation from the aforementioned orientation and elongation, and impaired the tight junctions, leading to a leaky endothelium. This novel, versatile, cost-effective, pathophysiologically relevant stretching device provides a useful platform for advancement of vascular disease research and treatment.

bioengineering↗

bioRxiv2021

Waning immune responses against SARS-CoV-2 among vaccinees in Hong Kong

BackgroundNearly 4 billion doses of the BioNTech-mRNA and Sinovac-inactivated vaccines have been administrated globally, yet different vaccine-induced immunity against SARS-CoV-2 variants of concern (VOCs) remain incompletely investigated. MethodsWe compare the immunogenicity and durability of these two vaccines among fully vaccinated Hong Kong people. FindingsStandard BioNTech and Sinovac vaccinations were tolerated and induced neutralizing antibody (NAb) (100% and 85.7%) and spike-specific CD4 T cell responses (96.7% and 82.1%), respectively. The geometric mean NAb IC50 and median frequencies of reactive CD4 subsets were consistently lower among Sinovac-vaccinees than BioNTech-vaccinees. Against VOCs, NAb response rate and geometric mean IC50 against B1.351 and B.1.617.2 were significantly lower for Sinovac (14.3%, 15 and 50%, 23.2) than BioNTech (79.4%, 107 and 94.1%, 131). Three months after vaccinations, NAbs to VOCs dropped near to detection limit, along with waning memory T cell responses, mainly among Sinovac-vaccinees. InterpretationOur results indicate that Sinovac-vaccinees may face higher risk to pandemic VOCs breakthrough infection. FundingThis study was supported by the Hong Kong Research Grants Council Collaborative Research Fund (C7156-20GF to Z.C and C1134-20GF); the National Program on Key Research Project of China (Grant 2020YFC0860600, 2020YFA0707500 and 2020YFA0707504); Shenzhen Science and Technology Program (JSGG20200225151410198 and JCYJ20210324131610027); HKU Development Fund and LKS Faculty of Medicine Matching Fund to AIDS Institute; Hong Kong Innovation and Technology Fund, Innovation and Technology Commission and generous donation from the Friends of Hope Education Fund. Z.C.s team was also partly supported by the Theme-Based Research Scheme (T11-706/18-N).

immunology↗