Biology subjects

Man, K.

Publications and source records attributed to Man, K..

9 recordsLinked to original sources

bioRxiv2026

Osteoimmunomodulatory Stem Cell Nanoghosts as a Novel Nanotherapeutic for Bone Regeneration

Critical-sized bone defects and implant-associated complications are often exacerbated by chronic inflammation, which compromises tissue repair and implant integration. Mesenchymal stromal cell (MSC)-derived extracellular vesicles have emerged as promising immunomodulatory nanotherapeutics; however, their clinical translation remains constrained by low yield, heterogeneity, and poor scalability. Here we present a bioengineered MSC-derived nanoghosts platform designed to overcome these translational barriers while enabling tunable osteoimmunomodulatory function. By coupling high-yield nanoghost fabrication with biomimetic MSC conditioning, we demonstrate that oxygen tension (5 or 21% O2) and 3D culture substrates (5 or 15 wt-% GelMA) can reprogram MSC immunophenotype. Nanoghosts generated under hypoxic and 3D conditions displayed enriched anti-inflammatory cargo, preserved MSC viability under inflammatory stress, and partially rescued osteogenic mineralization in the presence of pro-inflammatory cytokines. Together, these findings showcase MSC nanoghosts as scalable and bioactive immunoregulatory nanotherapeutic capable of modulating immune-bone crosstalk, providing a translational strategy to mitigate inflammation-driven impairment of bone regeneration and implant integration. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=90 SRC="FIGDIR/small/724218v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@f965deorg.highwire.dtl.DTLVardef@18f007borg.highwire.dtl.DTLVardef@168a194org.highwire.dtl.DTLVardef@4818fe_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2025

Refining the Bio-manufacturing of Microalgae-derived Extracellular Vesicles as a Potential Nanotherapeutic for Osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease marked by oxidative stress, chronic inflammation, and cartilage degradation. Current treatments are limited and fail to address the underlying disease mechanisms. Extracellular vesicles (EVs) have emerged as promising nanotherapeutics; however, mammalian-derived EVs face cost and scalability challenges. Microalgae represent a sustainable alternative, yet their potential as EV biofactories for regenerative medicine remains unknown. This study aims to refine the bio-manufacturing of microalgae EVs as a next-generation nanotherapeutic for OA. Microalgae species (Chlorella sorokiniana, Synechococcus sp., Leptolyngbya sp., Chlamydomonas reinhardtii CC1690) were screened under varying photoperiods (0h, 16h, 24h light/day) to assess the influence on viability, growth and EV production. EVs were characterized by transmission electron microscopy, nanoparticle tracking analysis, protein quantification and immunoblotting. Their antioxidant capacity, cellular recruitment, and therapeutic efficacy were evaluated in a cytokine-induced OA-like in vitro model. Our findings demonstrated that microalgae growth and EV yield were highly light-dependent, with all species maintaining high viability (>80%) across different photoperiods. Notably, Leptolyngbya sp. (Leptolyngbya) exhibited the fastest growth and highest EV yield under extended illumination, producing EVs with strong antioxidant activity. Leptolyngbya-derived EVs (Lepto-EVs) enhanced the proliferation and migration of human bone marrow-derived mesenchymal stromal cells and provided protection against matrix degradation within a cytokine-induced OA-like model. These findings position microalgae, particularly Leptolyngbya, as a highly scalable and sustainable producer of therapeutic EVs. Lepto-EVs offer a potent, cell-free nanotherapeutic exhibiting anti-catabolic properties alleviating cytokine-induced matrix degradation in an OA-like milieu, establishing microalgae EVs as a promising, cost-effective frontier in regenerative nanomedicine. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=98 SRC="FIGDIR/small/685512v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@ac6400org.highwire.dtl.DTLVardef@1d948a7org.highwire.dtl.DTLVardef@30fc13org.highwire.dtl.DTLVardef@1f576c8_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2025

Bioengineering Developmentally Inspired Matrix Vesicles as Designer Nanotherapeutics for Bone Regeneration

Extracellular vesicles (EVs) are emerging as promising acellular nanotherapeutics for musculoskeletal repair. Matrix vesicles, a matrix-bound subset of EVs, are essential mediators of endochondral ossification in bone development and fracture repair. This study aims to design bioengineered matrix vesicles from hypertrophic cartilage microtissues to drive endochondral ossification for bone repair. Human mesenchymal stromal cell (hBMSC) microtissues were differentiated with/without BMP2 in chondrogenic or hypertrophic medium. Isolated matrix vesicles were characterized for physiochemical properties and biological functionality. BMP2 and hypertrophic conditioning significantly increased vesicle yield (1.5-fold), alkaline phosphatase activity (3.24-fold), calcium binding capacity (8.82-fold), and growth factor content (BMP2, VEGF). These vesicles promoted proliferation, migration, and mineralization of hBMSCs and enhanced angiogenesis in human endothelial colony forming cells (hECFCs), with BMP2 and hypertrophically conditioned vesicles showing the most pronounced effects. Proteomics analysis confirmed the enrichment of proteins involved in extracellular matrix remodelling, mineral deposition and vascularization within these hypertrophically engineered vesicles. These findings demonstrate that hypertrophic induction of cartilaginous microtissues substantially improves the yield and therapeutic potential of matrix vesicles. Taken together, this research unveils a powerful strategy to bioengineer developmentally inspired vesicles that not only recapitulate key cues of endochondral ossification but offers a tailorable, multifunctional nanotherapeutic platform for improved bone regeneration strategies. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=112 SRC="FIGDIR/small/684111v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@17327a9org.highwire.dtl.DTLVardef@1310583org.highwire.dtl.DTLVardef@160f095org.highwire.dtl.DTLVardef@152eff0_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2025

Molecular determinants of brain-resident CD8+ T cell formation and function

Tissue-resident memory T (Trm) cells are strategically located to provide frontline protection upon antigen re-encounter while possessing tissue-specific transcriptional programs. Whether brain Trm cells similarly adapt to their tissue environment, and to what extent their molecular signature is altered in neuropathology, remains unclear. Here we profile brain Trm cells under homeostasis and in the contexts of aging, beta-amyloidosis, and systemic viral infection. From these studies, a tissue-specific CD8+ T cell landscape emerged, defined by the expression of the transcription factor TCF-1 and the inhibitory receptor PD-1. TCF-1 was critical for the formation and phenotypic maturation of brain CD8+ Trm cells, while PD-1 signaling was necessary for robust effector function and antigen-specific recall response. In addition, the cytokine transforming growth factor (TGF)-{beta} was required for the differentiation of brain CD8+ Trm cells and restricted their transition into effector-like cells upon antigenic rechallenge. These findings highlight common as well as tissue-specific features of brain CD8+ Trm cells and provide insights into the molecular mechanisms governing their formation and function.

immunology↗

bioRxiv2025

Engineering Extracellular Vesicle Production through Magnetic Ion Channel Activation for Bone Regeneration

Bone disorders represent a significant global health challenge. Extracellular vesicles (EVs) are emerging as a promising nanotherapeutic approach for bone regeneration, addressing the translation barriers associated with cell-based therapies. Despite their immense potential, the clinical application of EVs is limited by low production yields and inconsistent quality. Magnetic Ion Channel Activation (MICA) utilises remote magnetic fields to stimulate mechano-sensitive ion channels through magnetic nanoparticles (MNPs). This study explores the potential of utilising MICA to enhance the production yield and therapeutic efficacy of EVs for bone regeneration. The findings demonstrate that MICA significantly increased the production yield of EVs from MC3T3 pre-osteoblasts compared to magnetic stimulation or TREK1 functionalised graphene oxide-MNP particles alone. The obtained EVs exhibited typical size distribution, morphology, and EV protein expression consistent with nano-sized vesicles. Furthermore, MICA/TREK EVs treatment considerably enhanced human bone marrow-derived mesenchymal stem cells osteogenic differentiation and mineralisation compared to EVs derived from MICA, TREK, or untreated groups. Proteomics analysis revealed the enrichment of proteins involved in mechanotransduction and osteogenic differentiation within MICA/TREK EVs. In summary, these findings highlight the substantial potential of MICA as a platform to enhance the scalable production and therapeutic application of pro-regenerative EVs for bone augmentation strategies.

bioengineering↗

bioRxiv2023

Nanoparticle targeting of mechanically modulated glycocalyx

The mechanical properties and forces in the extracellular environment surrounding alveolar epithelial cells have the potential to modulate their behavior. Particularly, breathing applies 3-dimensional cyclic stretches to the cells, while the stiffness of the interstitium changes in disease states, such as fibrosis and cancer. A platform was developed that effectively imitates the active forces in the alveolus, while allowing one to control the interstitium matrix stiffnesses to mimic fibrotic lung tumor microenvironments. Alveolar epithelial cancer cells were cultured on these platforms and changes in the glycocalyx expression were evaluated. A complex combination of stiffness and dynamic forces altered heparan sulfate and chondroitin sulfate proteoglycan expressions. Consequently, we designed liposomal nanoparticles (LNPs) modified with peptides that can target heparan sulphate and chondroitin sulfates of cell surface glycocalyx. Cellular uptake of these modified nanoparticles increased in stiffer conditions depending on the stretch state. Namely, chondroitin sulfate A targeting improved uptake efficiency in cells experiencing dynamic stretches, while cells seeded on static stiff interstitium preferentially took up heparan sulfate targeting LNPs. These results demonstrate the critical role that mechanical stiffness and stretching play in the alveolus and the importance of including these properties in nanotherapeutic design for cancer treatment.

bioengineering↗

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↗