Biology subjects

Zamboulis, D. E.

Publications and source records attributed to Zamboulis, D. E..

4 recordsLinked to original sources

bioRxiv2026

Unravelling the distinct phenotype and mechanosensitive properties of different tendon cell populations.

Tendinopathy arises from maladaptive cellular responses, though the drivers remain unclear. Here we identify and characterise a previously undescribed tendon cell population residing within interfascicular matrix (IFM), demonstrating its importance as the primary mechanosensitive cell in tendon. We describe the first successful isolation and long-term culture of primary IFM and fascicular matrix (FM) cells, enabling direct comparison of their phenotypes and mechanosensitivity. IFM cells exhibited a potent response to stiff substrates, displaying cytoskeletal remodelling, rapid drifting of tenogenic and ECM gene expression, and proliferative decline, while FM cells remained largely unaltered. Crucially, transferring IFM cells to compliant, IFM-like substrates recovered their proliferative capacity, morphology, gene expression. This work defines IFM cells as the primary mechanosensitive tendon cell population, with implications for tendon ageing, injury, and regeneration. Importantly, it also enables identification of cell surface markers to isolate this population from other tendons, opening new avenues to explore mechanobiology-guided tendon therapeutics.

bioengineering↗

bioRxiv2023

The interfascicular matrix of energy storing tendons houses heterogenous cell populations disproportionately affected by ageing

Energy storing tendons such as the human Achilles and equine superficial digital flexor tendon (SDFT) are prone to injury, with incidence increasing with ageing. The interfascicular matrix (IFM), which binds tendon fascicles, plays a key role in energy storing tendon mechanics, and ageing alterations to the IFM negatively impact tendon function. While the mechanical role of the IFM in tendon function is well-established, the biological role of IFM-resident cell populations remains to be elucidated. Therefore, the aim of this study was to identify IFM-resident cell populations and establish how these populations are affected by ageing. Cells from young and old SDFTs were subjected to single cell RNA-sequencing, and immunolabelling for markers of each resulting population used to localise cell clusters. Eleven cell clusters were identified, including tenocytes, endothelial cells, mural cells and immune cells. One tenocyte cluster localised to the fascicular matrix, whereas nine clusters localised to the IFM. Interfascicular tenocytes and mural cells were preferentially affected by ageing, with differential expression of genes related to senescence, dysregulated proteostasis and inflammation. This is the first study to uncover the importance of the IFM niche for a diverse range of cell populations, and to identify age-related alterations specific to IFM-localised cells.

cell biology↗

bioRxiv2021

Structure-function Specialisation of the Interfascicular Matrix in the Human Achilles Tendon

ObjectiveTendon consists of highly aligned collagen-rich fascicles surrounded by interfascicular matrix (IFM). Some tendons act as energy stores to improve locomotion efficiency; these tendons are prone to debilitating injuries, the incidence of which increases with ageing. In equine tendons, energy storage is achieved primarily through specialisation of the IFM. However, no studies have investigated IFM structure-function specialisation in human tendons. Here, we compare the positional anterior tibialis and energy storing Achilles tendons, testing the hypothesis that the Achilles IFM has specialised composition and mechanical properties, which are lost with ageing. MethodsWe used a multidisciplinary combination of mechanical testing, immunolocalisation and proteomics to investigate structure-function specialisations in functionally distinct human tendons and how these are altered with ageing. ResultsThe IFM in the energy storing Achilles tendon is more elastic and fatigue resistant than the IFM in the positional anterior tibialis tendon, with a trend towards decreased fatigue resistance with age in the Achilles IFM. With ageing, alterations occur predominantly to the proteome of the Achilles IFM. ConclusionThe Achilles tendon IFM is specialised for energy storage, and changes to its proteome with ageing are likely responsible for the observed trends towards decreased fatigue resistance. Knowledge of key energy storing specialisations and their changes with ageing offers insight towards developing effective treatments for tendinopathy. Key messagesO_ST_ABSWhat is already known about this subject?C_ST_ABSO_LIEnergy storing tendons in animals and humans are particularly prone to tendinopathy and the incidence increases with increasing age. C_LIO_LIPrevious work in some animal models has shown that the specialisation of tendon properties for energy storage is achieved primarily through adaptation of the interfascicular matrix, with specialisation lost in ageing. However, the structural specialisations that provide the human Achilles tendon with its energy storing ability, and how these are affected by ageing, remain to be established. C_LI What does this study add?O_LIWe demonstrate that the interfascicular matrix in the human Achilles tendon is specialised for energy storing, with increased elastic recoil and fatigue resistance, and that these specialisations are partially lost with ageing, likely due to alterations to the proteome of the interfascicular matrix. C_LI How might this impact on clinical practice or future developments?O_LIShort term, the specialist IFM mechanics we have demonstrated can be detected with new developments in ultrasound functional imaging, offering improved opportunities for contextual tendinopathy diagnostics. Personalised rehabilitation programmes can now be explored and designed specifically to target IFM mechanics. C_LIO_LILonger term, the knowledge of key specialisations in injury prone energy storing tendons and how they are affected by ageing, offers crucial insight towards developing cell or tissue engineering treatments targeted at restoring tendon structure and function post-injury, specifically targeted at the IFM. C_LI

bioengineering↗

bioRxiv2020

Postnatal mechanical loading drives adaptation of tissues primarily through modulation of the non-collagenous matrix

Mature connective tissues demonstrate highly specialised properties, remarkably adapted to meet their functional requirements. Tissue adaptation to environmental cues can occur throughout life and poor adaptation commonly results in injury. However, the temporal nature and drivers of functional adaptation remain undefined. Here, we explore functional adaptation and specialisation of mechanically loaded tissues using tendon; a simple aligned biological composite, in which the collagen (fibre phase) and surrounding predominantly non-collagenous matrix (matrix phase) can be interrogated independently. Using an equine model of late development, we report the first phase-specific analysis of biomechanical, structural and compositional changes seen in functional adaptation, demonstrating adaptation occurs postnatally, following mechanical loading, and is almost exclusively localised to the non-collagenous matrix phase. These novel data redefine adaptation in connective tissue, highlighting the fundamental importance of non-collagenous matrix and suggesting that regenerative medicine strategies should change focus from the fibrous to the non-collagenous matrix phase of tissue.

cell biology↗