Biology subjects

Hoey, D. A.

Publications and source records attributed to Hoey, D. A..

8 recordsLinked to original sources

bioRxiv2025

Extracellular Vesicles-Mediated Crosstalk in Bone: miR-150-5p as a Mechanosensitive Inhibitor of Osteoclastogenesis

Bone is a dynamic tissue that is constantly remodelling via a tightly controlled balance between formation and resorption. However, when osteoclast-mediated resorption exceeds formation, it can lead to net bone loss and the development of osteoporosis. Osteoclastogenesis is regulated by local environmental cues, including paracrine factors released by resident cell populations. Extracellular vesicles (EVs) have recently emerged as key mediators of paracrine communication, though their role in osteoclastogenesis remains underexplored. Therefore, this study investigated how resident mesenchymal-derived bone cells and their secreted EVs modulate osteoclastogenesis, and delineate the signalling factors mediating this anti-catabolic communication. We demonstrate that the secretome of mesenchymal-derived bone cells inhibit osteoclast differentiation to differing degrees depending on the stage of lineage commitment and on the mechanical environment, and demonstrate that this inhibition is mediated via the release of EVs. In addition, we identified the terminally differentiated osteocyte as the optimal parent cell for the production of anti-catabolic EVs and demonstrated the importance EV dosage. Finally, we show that mechanosensitive miR-150-5p is packaged within osteocyte-derived EVs and inhibits osteoclast differentiation. Taken together, this study identifies mechanically-activated osteocyte derived EVs and miR-150-5p as key regulators of osteoclastogenesis and novel molecular therapies for skeletal pathologies.

bioengineering↗

bioRxiv2025

Mechanically activated bone cell derived extracellular vesicles regulate angiogenesis in a manner that is dependent on the stage of lineage commitment

Bone regeneration requires a finely tuned interplay between osteogenesis and angiogenesis. While current treatments such as auto/allografts, provide support, they often fail to promote adequate vascularisation necessary for complete repair. Extracellular vesicles (EVs), as mediators of intercellular communication, have emerged as promising acellular nanotechnologies for tissue regeneration due to their bioactive cargo and low immunogenicity. Mechanical stimulation, a known enhancer of bone cell function, can modulate EV cargo and potentially improve regenerative efficacy. In this study, we investigated how mechanical stimulation, and the stage of mesenchymal lineage commitment influence the angiogenic potential of secretomes and EVs derived from mesenchymal stromal/stem cells, osteoblasts, and osteocytes. Our findings reveal that both cell mechanical stimulation and their differentiation stage significantly modulate the angiogenic properties of the resulting EVs. Among the tested conditions, mechanically-stimulated osteocyte-derived EVs demonstrate superior angiogenesis, promoting endothelial cell migration, tube formation, and CD31 expression. These effects were further validated in a pre-clinical ex ovo chick chorioallantoic membrane assay, where robust neovascularisation was observed. This work highlights the critical role of both mechanical cues and cell differentiation stage in regulating the angiogenic capacity of EVs and proposes mechanically activated osteocyte-derived EVs as a novel pro-angiogenic nanotherapeutic for bone repair.

bioengineering↗

bioRxiv2023

Melt electrowritten scaffold architectures to mimic vasculature mechanics and control neo-tissue orientation

Cardiovascular disease is one of the leading causes of death worldwide, commonly associated with the development of an arteriosclerotic plaque and impairment of blood flow in arteries. Current adopted grafts to bypass the stenosed vessel fail to recapitulate the unique mechanical behaviour of native vessels, particularly in the case of small diameter vessels (<6 mm), leading to graft failure. Therefore, in this study, melt-electrowriting (MEW) was adopted to produce a range of fibrous grafts to mimic the extracellular matrix (ECM) architecture of the tunica media of vessels, in an attempt to match the mechanical and biological behaviour of the native tissue. Initially, the range of collagen architectures within the native vessel was determined, and subsequently replicated using MEW (winding angles (WA) 45{degrees}, 26.5{degrees}, 18.4{degrees}, 11.3{degrees}). These scaffolds recapitulated the anisotropic, non-linear mechanical behaviour of native carotid blood vessels. Moreover, these grafts facilitated human mesenchymal stromal/stem cell (hMSC) infiltration, differentiation, and ECM deposition that was independent of WA. The bioinspired MEW fibre architecture promoted cell alignment and preferential neo-tissue orientation in a manner similar to that seen in native tissue, particularly for WA 18.4{degrees} and 11.3{degrees}, which is a mandatory requirement for long-term survival of the regenerated tissue post-scaffold degradation. Lastly, the WA 18.4{degrees} was translated to a tubular graft and was shown to mirror the mechanical behaviour of small diameter vessels within physiological strain. Taken together, this study demonstrates the capacity to use MEW to fabricate bioinspired grafts to mimic the tunica media of vessels and recapitulate vascular mechanics which could act as a framework for small diameter graft development and functional long-term tissue regeneration.

bioengineering↗

bioRxiv2023

Mechanically activated bone cells drive vessel formation via an extracellular vesicle mediated mechanism

Blood vessel formation is an important initial step for bone formation during development as well as during remodelling and repair in the adult skeleton. This results in a heavily vascularized tissue where endothelial cells and skeletal cells are constantly in crosstalk to facilitate homeostasis, a process that is mediated by numerous environment signals, including mechanical loading. Breakdown in this communication can lead to disease and/or poor fracture repair. Therefore, this study aimed to determine the role of mature bone cells in regulating angiogenesis, how this is influenced by a dynamic mechanical environment, and understand the mechanism by which this could occur. Herein, we demonstrate that both osteoblasts and osteocytes coordinate endothelial cell proliferation, migration, and blood vessel formation via a mechanically dependent paracrine mechanism. Moreover, we identified that this process is mediated via the secretion of extracellular vesicles (EVs), as isolated EVs from mechanically stimulated bone cells elicited the same response as seen with the full secretome, while the EV depleted secretome did not elicit any effect. Despite mechanically activated bone cell derived EVs (MA-EVs) driving a similar response to VEGF treatment, MA-EVs contain minimal quantities of this angiogenic factor. Lastly, a miRNA screen identified mechanoresponsive miRNAs packaged within MA-EVs which are linked with angiogenesis. Taken together, this study has highlighted an important mechanism in osteogenic-angiogenic coupling in bone and has identified the mechanically activated bone cell derived EVs as a therapeutic to promote angiogenesis and potentially bone repair.

bioengineering↗

bioRxiv2022

Mechanoregulatory role of TRPV4 in prenatal skeletal development

Biophysical cues are essential for guiding skeletal development, but the mechanisms underlying the physical regulation of cartilage and bone formation are unknown. TRPV4 is a cell membrane ion channel responsible for transducing mechanical stimuli as a means of regulating skeletal cell homeostatic processes. Dysregulation of TRPV4 is associated with several skeletal developmental pathologies, indicating its involvement in cartilage and bone development, potentially in a mechanosensing capacity. In this study, we test the hypothesis that mechanically mediated prenatal skeletogenesis depends on TRPV4 activity. We first validate a novel model where we establish that dynamically loading embryonic mouse hindlimb explants cultured ex vivo promotes joint cartilage growth and morphogenesis, but not diaphyseal mineralization. We next reveal that TRPV4 protein expression is mechanically regulated and spatially localized to patterns of high biophysical stimuli in the femoral condyles of cultured limbs. Finally, we demonstrate that TRPV4 activity is crucial for the mechanical regulation of joint cartilage growth and shape, mediated via the control of cell proliferation and matrix biosynthesis, indicating a mechanism by which mechanical loading could direct morphogenesis during joint formation. We conclude that the regulatory pathways initiated by TRPV4 mechanotransduction are essential for the for the cartilage response to physical stimuli during skeletal development. Therefore, TRPV4 may be a valuable target for the development of therapeutic skeletal disease modifying drugs and developmentally-inspired tissue engineering strategies for skeletal repair.

developmental biology↗

bioRxiv2021

Mechanically Activated Extracellular Vesicle Functionalised Melt Electrowritten Materials for Bone Regeneration: A Mechano-Biomimetic Scaffold

1Mechanobiological cues arising directly via tissue/scaffold mechanics or indirectly via mechanically activated cell secretomes represent potent stimuli that mediate cell behaviour and tissue adaptation. Exploiting these cues in regeneration strategies holds great promise for tissue repair. In this study, we harness indirect biophysical cues originating from osteocytes in a combination with direct biophysical cues from Melt ElectroWritten (MEW) scaffolds to form a single engineered construct with the aim of synergistically enhancing osteogenesis. The secretome of mechanically activated osteocytes was collected within conditioned media (CM) and extracellular vesicles (EV) were subsequently isolated. Building on MEW micro-fibrous scaffolds with controlled microarchitecture and mineral nanotopography optimised for bone repair, a protocol was developed to functionalise these materials with CM or EVs. Human MSC proliferation was enhanced in both CM and EV functionalised scaffolds. EV functionalised scaffolds were further found to significantly enhance MSC osteogenesis, with enhanced alkaline phosphatase expression, collagen production, and mineralisation compared to control scaffolds. Furthermore, enhanced formation of mineralised nodules was identified in EV functionalised materials. Combining direct biophysical cues provided by the fibrous architecture/mineral nanotopography with the indirect cues provided by EVs, these constructs hold great promise to enhance the repair of damaged bone in a physiologically relevant manner.

bioengineering↗

bioRxiv2019

Melt electrowritten scaffolds with bone-inspired fibrous and mineral architectures to enhance BMP2 delivery and human MSC osteogenesis

1Material micro-architecture and chemistry play pivotal roles in driving cell behaviour. Bone at a cellular level consists of arranged fibres with a cross-fibrillar mineral phase made up of curved nano-sized needle shaped crystals. This nano-structured mineral architecture can bind and stabilise proteins within bone for centuries and thus holds promise as a strategy for therapeutic delivery in regenerative medicine. Herein, we use melt electrowriting (MEW) technology to create fibrous 3D PCL micro-architectures. These scaffolds were further modified with an extrafibrillar coating of plate shaped micron-sized calcium phosphate crystals (pHA), or with a novel extrafibrillar coating of needle shaped nano-sized crystals (nnHA). A third scaffold was developed whereby nano-sized crystals were placed intrafibrillarly during the MEW process (iHA). X-ray diffraction revealed altered crystal structure and crystallinity between groups, with hydroxyapatite (HA) being the primary phase in all modifications. Water contact angle was investigated revealing increased hydrophilicity with extrafibrillar coatings, while tensile testing revealed enhanced stiffness in scaffolds fabricated with intrafibrillar HA. Biological characterisation demonstrated significantly enhanced human stem/stromal cell mineralisation with extrafibrillar coatings, with a 5-fold increase in mineral deposition with plate like structures and a 14-fold increase with a needle topography, demonstrating the importance of bone mimetic architectures. Given the protein stabilising properties of mineral, these materials were further functionalised with BMP2. Extrafibrillar coatings of nano-needles facilitated a controlled release of BMP2 from the scaffold which further enhanced mineral deposition by osteoprogenitors. This study thus outlines a method for fabricating scaffolds with precise fibrous micro-architectures and bone mimetic nano-needle HA extrafibrillar coatings which significantly enhance mesenchymal stem/stromal cell (MSC) osteogenesis and therapeutic delivery and thus hold great promise for bone tissue regeneration.

bioengineering↗

bioRxiv2019

Human bone marrow mesenchymal stem/stromal cell behaviour is coordinated via mechanically activated osteocyte-derived extracellular vesicles

Osteocytes are mechanosensitive cells that are believed to play a fundamental role in coordinating bone mechanoadaptation via the secretion of paracrine factors. However, the exact mechanisms by which osteocytes relay mechanical signals to effector cells is poorly understood. In this study, we demonstrated that osteocytes subjected to a physiologic fluid shear secrete a distinct collection of factors that significantly enhance human MSC recruitment and osteogenesis. Utilising proteomics we generated an extensive map of proteins within the mechanically activated osteocyte secretome, identifying numerous paracrine factors that are modified by mechanical stimulation. Moreover, we identified the presence of extracellular vesicles (EVs) and further demonstrated that these mechanically activated osteocyte derived EVs (MAEVs) coordinate human MSCs recruitment and osteogenesis. This indicates that mechanical conditioning of parent cells can modify EVs and demonstrates the pro-osteogenic potential of MAEVs as a cell-free therapy to enhance bone regeneration and repair in diseases such as osteoporosis.

physiology↗