Biology subjects

Staines, K. A.

Publications and source records attributed to Staines, K. A..

13 recordsLinked to original sources

bioRxiv2026

A frameshift mutation in PRICKLE1 causes skeletal dysplasia in Cheviot sheep

Skeletal dysplasias can occur in animals, including humans, and are attributed to both environmental and genetic causes. As our understanding of the distinguishing phenotypes of different skeletal dysplasias improves, alongside elucidation of the mechanisms and genetic networks that contribute to skeletal development, identifying and controlling genetic mutations in livestock populations has become increasingly possible, including approaches beyond selective breeding alone. Within Scotland an 'achondroplasia' syndrome that was first described in the South Country Cheviot breed of sheep (OMIA 000004-9940), has continued to occur periodically within the same geographical locations, despite culling of affected lambs over many decades. Affected lambs exhibit rounded heads, short legs, a loss of hooves, abnormal stance and short twisted tails. As the condition has been observed in flocks and as progeny from specific ram and ewe matings, and cases have been co-twinned to normal siblings, this suggests a syndrome caused by a recessive genetic condition rather than environmental factors. Through homozygosity mapping and whole genome sequence analyses, we identified a 10 bp deletion in the open reading frame of the PRICKLE1 gene that encodes prickle planar cell polarity protein 1 and is essential for normal vertebrate embryonic development. We identified additional phenotypes present in affected lambs, including a loss of phalanges, neural tube defects, vertebral and articular chondrocyte defects, hair orientation differences and polycystic kidneys, consistent with a loss of PRICKLE1 function based on comparisons to mouse mutant lines. These findings enabled the development of a simple DNA test for the identified PRICKLE1 mutation that was made commercially available to facilitate the elimination of this genetic disease from sheep flocks.

genetics↗

bioRxiv2026

Articular calcified cartilage microarchitecture has a predictive role in abnormal osteochondral strain distributions in murine age-related osteoarthritis

Even though osteoarthritis is considered a disease of the whole joint, integrated analysis of articular calcified cartilage (ACC) behaviour with adjacent tissues remains a persistent limitation. Herein, we performed synchrotron X-ray computed tomography in intact loaded joints and coupled anatomical analysis with digital volume correlation to examine whether microarchitectural ACC features serve as predictive mechano-biomarkers of osteoarthritis. We reveal that male osteoarthritis-prone STR/Ort mice have thicker yet more porous ACC that contains larger but less spherical chondrocyte lacunae than their healthy parental-control CBA mice. This was linked to asymmetrical distribution of tensile and compressive strains generated under physiological loads in the ACC and underlying subchondral bone in tibial epiphyses of STR/Ort mice. Together these data suggest that murine ACC microarchitecture has a mechano-predictive role in age-related osteoarthritis.

physiology↗

bioRxiv2026

TNAP and PHOSPHO1 function synergistically to afford critical control over the mineralisation of the postnatal murine skeleton

Biomineralisation is essential for skeletal integrity, yet the synergistic roles of tissue non-specific alkaline phosphatase (TNAP) and PHOSPHO1 in postnatal bone mineralisation remain poorly defined. To decipher this, we generated a novel murine model in which Alpl was deleted in Prx1- expressing cells (AlplPrx1/Prx1) in mice with a global Phospho1-/- deficiency to overcome the perinatal lethality that arises upon dual global deletion. Using a multi-modal approach to spatially phenotype the limbs of these animals, we reveal mice lacking both TNAP and PHOSPHO1 exhibit a distinct lack of mineralisation and altered anatomical structure at postnatal day 1 (PN1) and 3-weeks of age. Although viable, these mice did not thrive due to their reduced size, thus further investigations were conducted on mice with a heterozygous deletion of TNAP (Alplwt/Prx1;Phospho1-/-). Although smaller than wild-types at PN1 and 3 weeks old, these mice did not display the gross limb deformations observed in the homozygous animals and the single, functioning Alpl allele rescued the loss of biomineralisation observed following dual phosphatase deletion. At 6-weeks of age, compromised epiphyses and metaphyses were only seen in AlplPrx1/Prx1 animals. Further, we found that tibial geometry and porosity was significantly altered by Phospho1 deletion (Phospho1-/-), which was compounded in the Alplwt/Prx1;Phospho1-/- mice and linked to alterations in collagen configuration, matrix mineralisation and growth plate deformities. Together, our findings establish the mechanistic framework for TNAP and PHOSPHO1 in permissive biomineralisation, providing critical insights into this fundamental process. Significance StatementBiomineralisation is essential for skeletal development and is critically dependent on phosphatases that release inorganic phosphate for hydroxyapatite formation. Our study investigates the dual role of PHOSPHO1 and TNAP in this process, using a novel murine knockout model. Deletion of both enzymes results in complete loss of bone mineralisation, demonstrating their critical synergistic function. Further, we show that PHOSPHO1 and TNAP exhibit distinct, spatially-restricted functions in the tibia and thus enhances our understanding of the fundamentals processes underpinning biomineralisation. These findings also have clinical relevance as they have the potential to inform on treatment strategies for hypo- and hyper-mineralised pathologies.

developmental biology↗

bioRxiv2026

Regulation and function of trans-physeal growth plate bridges: evidence for a mechanical base isolation role to minimise epiphyseal shear stress

The cartilaginous growth plate (GP) is responsible for all bone elongation during post-natal growth yet must simultaneously contribute to mechanical epiphyseal stability for articulation. How the GP balances these dual functions across the bone-cartilage-bone epiphyseal interface during complex load-growth transitions is not defined. Herein, we examine regulation and mechanobiology of GP bridges - mineralised trans-physeal GP structures - to explore whether they serve these dual GP functions. We have determined the effects of age and sex, short- and long-term joint loading and several established and new osteotropic pharmacological agents on mouse tibial GP bridge number and areal density using micro-computed tomography. We also explored temporal formation and progression of GP bridges by serial in vivo scanning and we imaged epiphyseal load-transfer in young and mature mice in situ via synchrotron X-ray computed tomography (sCT) of intact joints under physiologically oriented load. Our utilisation of digital volume correlation revealed regional 3D load-induced strain inhomogeneities in the GP that are synchronised to bridge location and this was substantiated using finite element modelling. Furthermore, direct micro- and sCT examinations showed that bridges consistently contain a singular epiphyseal/metaphyseal discontinuity which appear to serve a novel mechanical base isolation role to minimise shear stress across the GP. Our data indicate that bridges are regulatable, dynamic structures that synchronise GP strains and exhibit sensitivity to local joint mechanics. We highlight that trans-physeal bridges may contribute to longitudinal bone growth cessation whilst simultaneously stabilising the epiphysis by absorbing compression and shear strains.

bioengineering↗

bioRxiv2025

In situ profiling of nanoscale displacements uncovers mechano-architectural predictors of osteoarthritis emergence

Mechanical and anatomical interplay between the distinct tissues of the knee joint is essential for maintaining functional integrity during healthy ageing and contributes to the mechanisms that drive osteoarthritis (OA). In this study, we investigate how age- and disease-associated alterations in joint anatomy influence load transmission and tissue-level strain distribution. Using full-field synchrotron X-ray computed tomography coupled with digital volume correlation, we hierarchically characterised in situ nanoscale strains generated in response to mechanical loading across the tibial epiphysis. Our findings show that greater compressive strains accumulate in the articular condyle of male OA-prone (STR/Ort) epiphyses. Finite element modelling further demonstrated that these strain concentrations are associated with reduced load-bearing capacity, which arise from architectural differences localised to the subchondral bone plate. By coupling high-resolution imaging with computational modelling, our work provides new insights into how structural-function changes to joint anatomy contribute to the initiation and progression of mechanically driven OA. Our approach offers a means to identify early imaging biomarkers prior to OA diagnosis and has potential for monitoring interventions aimed at preserving joint mechanics while promoting healthy joint ageing.

bioengineering↗

bioRxiv2024

Sexually dimorphic effects of prenatal alcohol exposure on the murine skeleton

BackgroundPrenatal alcohol exposure (PAE) can result in lifelong disabilities known as foetal alcohol spectrum disorder (FASD) and is associated with childhood growth deficiencies and increased bone fracture risk. However, the effects of PAE on the adult skeleton remain unclear and any potential sexual dimorphism is undetermined. Therefore, we utilised a murine model to examine sex differences with PAE on in vitro bone formation, and in the juvenile and adult skeleton. MethodsPregnant C57BL/6J female mice received 5% ethanol in their drinking water during gestation. Primary calvarial osteoblasts were isolated from neonatal offspring and mineralised bone nodule formation and gene expression assessed. Skeletal phenotyping of 4- and 12-week-old male and female offspring was conducted by micro-computed tomography ({micro}CT), 3-point bending, growth plate analyses, and histology. ResultsOsteoblasts from male and female PAE mice displayed reduced bone formation, compared to control ([≤]30%). Bglap and Ahsg were upregulated with PAE in both sexes compared to control, whereas Vegfa, Bmp6, Tgfbr1 and Flt1 were downregulated in PAE male osteoblasts only. In 12-week-old mice, {micro}CT analysis revealed a sex and exposure interaction across several trabecular bone parameters. PAE was detrimental to the trabecular compartment in male mice compared to control, yet PAE females were unaffected. Both male and female mice had significant reductions in cortical parameters with PAE. Whilst male mice were negatively affected along the tibia length, females were only distally affected. Posterior cortical porosity was increased in PAE females only. Mechanical testing revealed PAE males had significantly reduced bone stiffness compared to controls; maximum load and yield was reduced in both sexes. PAE had no effect on total body weight or tibial bone length in either sex. However, total growth plate width in male PAE mice compared to control was reduced, whilst female PAE mice were unaffected. 4-week-old mice did not display the altered skeletal phenotype with PAE observed in 12-week-old animals. ConclusionsEvidence herein suggests for the first time that PAE exerts divergent sex effects on the skeleton, possibly influenced by underlying sex specific transcriptional mechanisms of osteoblasts. Establishing these sex differences will support future policies and clinical management of FASD. Plain English summaryPrenatal alcohol exposure (PAE) can lead to a set of lifelong cognitive, behavioural, and physical disabilities known as foetal alcohol spectrum disorder (FASD). FASD is a significant burden on healthcare, justice and education systems, which is set to worsen with rising alcohol consumption rates. FASD children have an increased risk of long bone fracture and adolescents are smaller in stature. However, sex differences and the long-term effects of PAE on the skeleton have not been investigated and was the aim of this study. Using a mouse model of PAE, we examined the function and gene expression of bone-forming cells (osteoblasts). We then analysed the skeletons of male and female mice at 12-weeks-old (adult) and 4-weeks-old (juvenile). PAE reduced osteoblast bone formation in both sexes, compared to control. Differential gene expression was predominantly observed in PAE males and largely involved genes related to blood vessel formation. High resolution x-ray imaging (micro-CT) revealed PAE had a detrimental effect on the inner trabecular bone component in 12-week-old male mice only. Analysis of the outer cortical bone revealed that whilst both male and female PAE mice were negatively affected, anatomical variations were observed. Mechanical testing also revealed differences in bone strength in PAE mice, compared to control. Interestingly, 4-week-old mice did not possess these sex differences observed in our PAE model at 12 weeks of age. Our data suggest PAE has detrimental and yet sex-dependent effects on the skeleton. Establishing these sex differences will support future policies and clinical management of FASD. HighlightsO_LIPrimary calvarial osteoblasts isolated from male and female PAE mice displayed reduced mineralised bone nodule formation and differential gene expression compared to control. C_LIO_LIPAE had a detrimental effect on trabecular bone parameters in 12-week-old male mice only. C_LIO_LIPAE leads to spatial variation in cortical bone parameters and geometry, with male mice negatively affected along the tibia length and female mice only affected at the distal end. C_LIO_LIMechanical testing revealed PAE male mice had significantly reduced bone stiffness compared to controls; PAE in both sexes reduced maximum load and yield. C_LIO_LI4-week-old mice did not display the altered skeletal phenotype with PAE observed in 12-week-old animals. C_LI

cell biology↗

bioRxiv2023

Mitochondrial dysfunction and mitophagy blockade contribute to renal osteodystrophy in chronic kidney disease-mineral bone disorder

Chronic kidney disease-mineral and bone disorder (CKD-MBD) presents with extra-skeletal calcification and renal osteodystrophy (ROD). The origins of ROD likely lie with elevated uremic toxins and/or an altered hormonal profile but the cellular events responsible remain unclear. Here, we report that stalled mitophagy contributes to mitochondrial dysfunction in bones of a CKD-MBD mouse model, and also human CKD-MBD patients. RNA-seq analysis exposed an altered expression of genes associated with mitophagy and mitochondrial function in tibia of CKD-MBD mice. The accumulation of damaged osteocyte mitochondria and the expression of mitophagy regulators, p62/SQSTM1, ATG7 and LC3 was inconsistent with functional mitophagy, and in mito-QC reporter mice with CKD-MBD, there was a 2.3-fold increase in osteocyte mitolysosomes. Altered expression of mitophagy regulators in human CKD-MBD bones was also observed. To determine if uremic toxins were possibly responsible for these observations, indoxyl sulfate treatment of osteoblasts revealed mitochondria with distorted morphology and whose membrane potential and oxidative phosphorylation were decreased, and oxygen-free radical production increased. The altered p62/SQSTM1 and LC3-II expression was consistent with impaired mitophagy machinery and the effects of indoxyl sulfate were reversible by rapamycin. In conclusion, mitolysosome accumulation from impaired clearance of damaged mitochondria may contribute to the skeletal complications, characteristic of ROD. Targeting mitochondria and the mitophagy process may therefore offer novel routes for intervention to preserve bone health in patients with ROD. Such approaches would be timely as our current armamentarium of anti-fracture medications has not been developed for, or adequately studied in, patients with severe CKD-MBD. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=113 SRC="FIGDIR/small/573355v1_ufig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@1f23caforg.highwire.dtl.DTLVardef@6e3e94org.highwire.dtl.DTLVardef@1ce6adeorg.highwire.dtl.DTLVardef@ca5558_HPS_FORMAT_FIGEXP M_FIG C_FIG TRANSLATIONAL STATEMENTRenal osteodystrophy (ROD) remains the major skeletal complication of chronic kidney disease-mineral and bone disorder (CKD-MBD). As a disease characterised by biochemical and hormone abnormalities, ROD is exacerbated by osteocyte mitochondrial dysfunction. Advances in our understanding of the mitophagy pathway are vital to improving the clinical management of ROD. The dysregulation of mitophagy in murine and human CKD-MBD bone provided evidence of delayed clearance of damaged mitochondria, which was also observed in uremic toxin-treated-osteoblasts but reversible upon rapamycin treatment. This study reveals the therapeutic potential of managing ROD by restoring defective mitophagy in osteocytes.

genomics↗

bioRxiv2021

Ciliary IFT88 safeguards coordinated epiphyseal vascularisation, resorption and ossification from disruptive physiological mechanical forces

In the musculoskeletal system, appropriate cell and tissue responses to mechanical force delineate morphogenesis and ensure lifelong health. Despite this, how mechanical cues are integrated into biological programmes remains unclear. Primary cilia are microtubule-based organelles that tune a range of cell activities, including signalling cascades activated or modulated, by extracellular biophysical cues. Here, we demonstrate that the inducible, cartilage-specific deletion of Intraflagellar transport protein 88 (IFT88), which reduces ciliation in the adolescent mouse growth plate (GP), uncouples chondrocyte differentiation from cartilage resorption and mineralisation in a mechano-dependent manner. Targeting IFT88, inhibits hypertrophic chondrocyte VEGF expression, vascular recruitment, osteoclastic activity and the replacement of cartilage with bone. These effects are largely restricted to peripheral tibial regions beneath the load-bearing compartments of the knee. Increases in physiological loading, in control mice, also impairs ossification in the peripheral GP, mimicking the effects of IFT88 deletion. Strikingly, limb immobilisation rescues disrupted VEGF and restores epiphyseal dynamics in Ift88cKO mice. These data indicate, that during this pivotal phase in adolescent skeletal maturation that defines the cessation of growth, ciliary IFT88 protects the coordinated ossification of the growth plate from an otherwise disruptive heterogeneity of physiological mechanical forces.

physiology↗

bioRxiv2021

Differential Expression of Alkaline Phosphatase and PHOSPHO1 in Bone from a Murine Model of Chronic Kidney Disease

Patients with advanced chronic kidney disease (CKD) often present with skeletal abnormalities; a condition known as renal osteodystrophy (ROD). While Tissue-nonspecific alkaline phosphatase (TNAP) and PHOSPHO1 are recognized to be critical for bone mineralization, their role in the etiology of ROD is unclear. To address this, ROD was induced in both wild-type and Phospho1 knockout (P1KO) mice using dietary adenine supplementation. The mice presented with hyperphosphatemia, hyperparathyroidism, and elevated levels of FGF23 and bone turnover markers. In particular, we noted that in CKD mice, bone mineral density (BMD) was increased in cortical bone (p < 0.05) but decreased in trabecular bone (p < 0.05). These changes were accompanied by decreased TNAP (p < 0.01) and increased PHOSPHO1 (p < 0.001) expression in wild-type CKD bones. In P1KO CKD mice, the cortical BMD phenotype was rescued, suggesting that the increased cortical BMD of CKD mice was driven by increased PHOSPHO1 expression. Other structural parameters were also improved in P1KO CKD mice. We further investigated the driver of the mineralization defects, by studying the effects of FGF23, PTH, and phosphate administration on PHOSPHO1 and TNAP expression by primary murine osteoblasts. We found both PHOSPHO1 and TNAP expression to be down-regulated in response to phosphate and PTH. While matrix mineralization was increased with phosphate (Pi), it decreased with PTH and FGF23 had no effect. The in vitro data suggest that the TNAP reduction in CKD-MBD is driven by the hyperphosphatemia and/or hyperparathyroidism noted in these mice, while the higher PHOSPHO1 expression may be a compensatory mechanism in an attempt to protect the bone from hypomineralization. We propose that increased PHOSPHO1 expression in ROD may contribute to the disordered skeletal mineralization characteristic of this progressive disorder.

cell biology↗

bioRxiv2021

The role of accelerated growth plate fusion in the absence of SOCS2 on osteoarthritis vulnerability

Osteoarthritis is the most prevalent systemic musculoskeletal disorder characterised by articular cartilage degeneration and subchondral bone (SCB) sclerosis. Here we sought to examine the contribution of accelerated growth to osteoarthritis development using a murine model of excessive longitudinal growth. Suppressor of cytokine signalling 2 (SOCS2) is a negative regulator of growth hormone (GH) signalling, thus mice deficient in SOCS2 (Socs2-/-) display accelerated bone growth. We examined vulnerability of Socs2-/- mice to osteoarthritis following surgical induction of disease (destabilisation of the medial meniscus (DMM)), and with ageing, by histology and micro-CT. We observed significant increase in number (WT DMM: 532{+/-}56; WT sham: 495{+/-}45; KO DMM: 169{+/-}49; KO sham: 187{+/-}56; P<0.01) and density (WT DMM: 2.2{+/-}0.9; WT sham: 1.2{+/-}0.5; KO DMM: 13.0{+/-}0.5; KO sham: 14.4{+/-}0.7) of growth plate bridges in Socs2-/- in comparison to wild-type (WT). Histological examination of WT and Socs2-/- knees revealed articular cartilage damage with DMM in comparison to sham (WT DMM: 3.4{+/-}0.4; WT sham: 0.3{+/-}0.05 (P<0.05); KO DMM: 3.2{+/-}0.8; KO sham: 0.8{+/-}0.3). Articular cartilage lesion severity scores (mean and maximum) were similar in WT and Socs2-/- mice with either DMM, or with ageing. Micro-CT analysis revealed significant decreases in SCB thickness, epiphyseal trabecular number and thickness in the medial compartment of Socs2-/-, in comparison to WT (P<0.001). DMM had no effect on the SCB thickness in comparison to sham in either genotype. Together these data suggest that enhanced GH signalling through SOCS2 deletion accelerates growth plate fusion, however this has no effect on osteoarthritis vulnerability in this model. Summary statementDeletion of SOCS2 results in accelerated growth plate fusion, however this has no effect on osteoarthritis vulnerability.

pathology↗

bioRxiv2021

Proton pump inhibitors inhibit PHOSPHO1 activity and matrix mineralisation in vitro

Proton pump inhibitors (PPIs) have been associated with an increased risk of fragility fractures in pharmaco-epidemiological studies. The mechanism is unclear but it has been speculated that by neutralising gastric acid, they may reduce intestinal calcium absorption, causing secondary hyperparathyroidism and bone loss. Here we investigated that hypothesis that the skeletal effects of PPI might be mediated by inhibitory effects on the bone-specific phosphatase PHOSPHO1. We found that the all PPI tested potential inhibited the activity of PHOSPHO1 with IC50 ranging between 0.73M for esomeprazole to 19.27M for pantoprazole. In contrast, these PPIs did not inhibit TNAP activity. We also found that mineralisation of bone matrix in primary osteoblast cultures inhibited by several PPI in a concentration dependent manner. In contrast, the histamine-2 receptor antagonists (H2RA) nizatidine, famotidine, cimetidine and ranitidine had no inhibitory effects on PHOSPHO1 activity. Our experiments shown for the first time that PPI inhibit PHOSPHO1 activity and matrix mineralisation in vitro revealing a potential mechanism by which these widely used drugs are associated with the risk of fractures.

cell biology↗

bioRxiv2020

Ubiquitin-protein ligase Ubr5 cooperates with Hedgehog signalling to promote skeletal tissue homeostasis

Mammalian Hedgehog (HH) signalling pathway plays an essential role in tissue homeostasis and its deregulation is linked to rheumatological disorders. UBR5 is the mammalian homologue of the E3 ubiquitin-protein ligase Hyd, a negative regulator of the Hh-pathway in Drosophila. To investigate a possible role of UBR5 in regulation of the musculoskeletal system through modulation of mammalian HH signaling, we created a mouse model for specific loss of Ubr5 function in limb bud mesenchyme. Our findings revealed a role for UBR5 in maintaining cartilage homeostasis and suppressing metaplasia. Ubr5 loss of function resulted in progressive and dramatic articular cartilage degradation, enlarged, abnormally shaped sesamoid bones and extensive heterotopic tissue metaplasia linked to calcification of tendons and ossification of synovium. Genetic suppression of smoothened (Smo), a key mediator of HH signalling, dramatically enhanced the Ubr5 mutant phenotype. Analysis of HH signalling in both mouse and cell model systems revealed that loss of Ubr5 stimulated canonical HH-signalling while also increasing PKA activity. In addition, human osteoarthritic samples revealed similar correlations between UBR5 expression, canonical HH signalling and PKA activity markers. Our studies identified a crucial function for the Ubr5 gene in the maintenance of skeletal tissue homeostasis and an unexpected mode of regulation of the HH signalling pathway. Author SummaryUbiquitin ligases modify proteins post-translationally which is essential for a variety of cellular processes. UBR5 is an E3 ubiquitin ligase and in Drosophila is a regulator of Hedgehog signaling. In mammals, the Hedgehog (HH) signalling pathway, among many other roles, plays an essential role in tissue maintenance, a process called homeostasis. A murine genetic system was developed to specifically eliminate UBR5 function from embryonic limb tissue that subsequently forms bone and connective tissue (ligaments and tendons). This approach revealed that UBR5 operates as a potent suppressor of excessive growth of normal cartilage and bone and prevents formation of bone in ectopic sites in connective tissue near the knees and ankle joints. In contrast to abnormal growth, UBR5 inhibits degradation of the articular cartilage that cushions the knee joint leading to extensive exposure of underlying bone. Furthermore, Ubr5 interacts with smoothened, a component of the HH pathway, identifying UBR5 as a regulator of mammalian HH signaling in the postnatal musculoskeletal system. In summary, this work shows that UBR5 interacts with the HH pathway to regulate skeletal homeostasis in and around joints of the legs and identifies targets that may be harnessed for biomedical engineering and clinical applications.

genetics↗

bioRxiv2020

Characterisation of growth plate dynamics in murine models of osteoarthritis

BackgroundThe purpose of this study was to investigate growth plate dynamics in surgical and loading murine models of osteoarthritis, to understand whether abnormalities in these dynamics predict osteoarthritis vulnerability. Methods8-week-old C57BL/6 male mice underwent destabilisation of medial meniscus (DMM) (n = 8) surgery in right knee joints. Contralateral left knee joints had no intervention (controls). In 16-week-old C57BL/6 male mice (n = 6), osteoarthritis was induced using non-invasive mechanical loading of right knee joints with peak force of 11N. Non-loaded left knee joints were internal controls. Chondrocyte transiency in tibial articular cartilage and growth plate was confirmed by histology and immunohistochemistry. Tibial subchondral bone parameters were measured using microCT and correlated to 3D GP bridging analysis. ResultsHigher expression of chondrocyte hypertrophy markers; Col10a1 and MMP13 were observed in tibial articular cartilage chondrocytes of DMM and loaded mice. In tibial growth plate, Col10a1 and MMP13 expressions were widely dispersed in a significantly enlarged zones of proliferative and hypertrophic chondrocytes in DMM (p=0.002 and p<0.0001, respectively) and loaded (both p<0.0001) tibiae of mice compared to their controls. 3D quantification revealed enriched growth plate bridging and higher bridge densities in medial compared to lateral tibiae of DMM and loaded knee joints of the mice. Growth plate dynamics were associated with higher subchondral bone volume fraction (BV/TV; %) in medial tibiae of DMM and loaded knee joints and epiphyseal trabecular bone volume fraction in medial tibiae of loaded knee joints. ConclusionsThe results confirm articular cartilage chondrocyte transiency in a surgical and loaded murine model of osteoarthritis. Herein, we reveal for the first time spatial variation of growth plate bridging in surgical and loaded osteoarthritis models and how these may contribute to anatomical variation in vulnerability of osteoarthritis development.

physiology↗