Biology subjects

Comerford, E.

Publications and source records attributed to Comerford, E..

9 recordsLinked to original sources

bioRxiv2026

Pathological musculoskeletal characterisation of a new model of spontaneous OA in CD1 mice.

Osteoarthritis (OA) is a whole joint disease involving pathological changes in cartilage, synovium, ligaments, menisci and periarticular muscle. This study provides a comprehensive musculoskeletal characterisation of spontaneous OA in male CD1 mice to evaluate their suitability as a model of naturally occurring disease. Knee joints from 3-4 and 6-8 month old mice were analysed histologically, OARSI scoring and immunohistochemistry for markers of chondrogenesis and endochondral ossification. Quadriceps and gastrocnemius muscles were examined for fibre cross sectional area. CD1 mice displayed mild OA at 3-4 months, progressing to moderate to severe disease by 6-8 months. Cartilage loss, synovial hyperplasia and fibrosis increased across compartments. Anterior cruciate and collateral ligaments, and medial meniscus exhibited marked pathological remodelling, including proteoglycan rich rounded cell regions and evidence of endochondral ossification with increased COL2, SOX9, RUNX2 and ASPN expression. Gastrocnemius muscle showed significant atrophy at 6-8 months, correlating with OA severity, whereas quadriceps atrophy was not significant. These findings establish CD1 mice as a robust spontaneous OA model that recapitulates the multi-tissue complexity of human disease. Because CD1 mice are globally available, cost-effective, genetically diverse and frequently, this model offers a practical and translationally relevant platform for investigating whole-joint organ mechanisms of OA progression and for evaluating therapies aimed at modifying disease across the entire joint.

pathology↗

bioRxiv2021

Age-related changes in microRNAs expression in cruciate ligaments of wild-stock house mice

AimCruciate ligaments (CLs) of the knee joint are commonly injured following trauma or ageing. MicroRNAs (miRs) are potential therapeutic targets in musculoskeletal disorders. This study aimed to 1) identify if wild-stock house (WSH) mice are an appropriate model to study age-related changes of the knee joint and 2) investigate expression of miRs in ageing murine CLs. MethodsKnee joints were collected from 6 and 24 months old C57BL/6 and WSH mice (Mus musculus domesticus) for histological analysis. RNA extraction and qPCR gene expression were performed on CLs in 6, 12, 24, and 30 month WSH old mice. Expression of miR targets in CLs was determined, followed by analysis of predicted mRNA target genes and Ingenuity Pathway Analysis. ResultsHigher CL and knee OARSI histological scores were found in 24 month old WSH mice compared to 6 and 12 month old C57BL/6 and 6 month old WSH mice (p< 0.05). miR-29a and miR-34a were upregulated in 30 month-old WSH mice in comparison to 6, 12 and 24-month-old WSH mice (p<0.05). Ingenuity Pathway Analysis on miR-29a and 34a targets was associated with inflammation through interleukins, TGF{beta} and Notch genes and p53 signalling. Collagen type I alpha 1 chain (COL1A1) correlated negatively with both miR-29a (r= -0.35) and miR-34a (r= -0.33). ConclusionThe findings of this study support WSH house mice as an accelerated ageing model of the murine knee joint. This study also indicated that miR-29a and 34a may be important regulators of COL1A1 gene expression in murine CLs.

molecular biology↗

bioRxiv2021

Biomechanics of aging and osteoarthritic human knee ligaments

BackgroundLigaments work to stabilize the human knee joint and prevent excessive movement. Whilst ligaments are known to decline in structure and function with aging, there has been no systematic effort to study changes in gross mechanical properties in the four major human knee ligaments due to osteoarthritis (OA). This study aims to collate material properties for the anterior (ACL) and posterior (PCL) cruciate ligaments, medial (MCL) and lateral (LCL) collateral ligaments. Our cadaveric samples come from a diverse demographic from which the effects of aging and OA on bone and cartilage material properties have already been quantified. Therefore, by combining our previous bone and cartilage data with the new ligament data from this study we are facilitating subject-specific whole-joint modelling studies. MethodsThe demographics of the collected cadaveric knee joints were diverse with age range between 31 to 88 years old, and OA International Cartilage Repair Society grade 0 to 4. Twelve cadaveric human knee joints were dissected, and bone-ligament-bone specimens were extracted for mechanical loading to failure. Ligament material properties were determined from the load-extension curves, namely: linear and ultimate (failure) stress and strain, secant modulus, tangent modulus, and stiffness. ResultsThere were significant negative correlations between age and ACL linear force (p=0.01), stress (p=0.03) and extension (p=0.05), ACL failure force (p=0.02), stress (p=0.02) and extension (p=0.02), PCL secant (p=0.02) and tangent (p=0.02) modulus, and LCL stiffness (p=0.05). Significant negative correlations were also found between OA grades and ACL linear force (p=0.05), stress (p=0.02), extension (p=0.01) and strain (p=0.03), and LCL failure stress (p=0.05). However, changes in age or OA grade did not show a statistically significant correlation with the MCL tensile parameters. Trends showed that almost all the tensile parameters of the ACL and PCLs decreased with increasing age and progression of OA. Due to small sample size, the combined effect of age and presence of OA could not be statistically derived. ConclusionsThis research is the first to correlate changes in tensile properties of the four major human knee ligaments to aging and OA. The current ligament study when combined with our previous findings on bone and cartilage for the same twelve knee cadavers, supports conceptualization of OA as a whole-joint disease that impairs the integrity of many peri-articular tissues within the knee. The subject-specific data pool consisting of the material properties of the four major knee ligaments, subchondral and trabecular bones and articular cartilage will aid reconstruction and graft replacements and advance knee joint finite element models, whilst knowledge of aged or diseased mechanics may direct future therapeutic interventions.

bioengineering↗

bioRxiv2021

The anterior cruciate ligament in murine post-traumatic osteoarthritis: markers and mechanics

1Osteoarthritis (OA) is a whole joint disease that affects all knee joint tissues. Ligaments, a matrix-rich connective tissue, play an important mechanical function that stabilises the knee joint and yet their role in OA is not well studied. Recent studies have shown that ligament extracellular matrix (ECM) structure is compromised in the early stages of OA, but it remains unclear how this affects ligament function and biomechanics. In this study, the aim was to investigate the structural, cellular and viscoelastic changes in the anterior cruciate ligament (ACL) in a murine non-invasive post-traumatic OA (PTOA) model. Non-invasive mechanical loading of the knee joint of C57BL/6J mice (10-week-old) was used as a PTOA model. Knee joints were analysed for joint space mineralisation and the ACLs were assessed with histology and mechanical testing. PTOA knee joints had a 33-46% increase in joint space mineralisation and PTOA knee joint ACLs exhibited ECM modifications, including collagen birefringence and COL2 and proteoglycan deposition. ECM changes were associated with cells expressing chondrogenic markers (SOX9 and RUNX2) expanding from the tibial enthesis to the ACL midbody. Viscoelastic and mechanical changes in the ACLs from PTOA knee joints included a 20-21% decrease in tangent modulus at 2MPa of stress, and a decrease strain rate sensitivity at higher strain rates and a significant increase in relaxation during stress-relaxation, but no changes to hysteresis and ultimate load to failure. These results demonstrate that ACL pathology and viscoelastic function is compromised in murine PTOA knee joints and provides further evidence of the important role of ligaments in the knee joint organ in health and disease.

pathology↗

bioRxiv2020

Viscoelastic characteristics of the canine cranial cruciate ligament complex at slow strain rates

Ligaments including the cruciate ligaments support and transfer loads between bones applied to the knee joint organ. The functions of these ligaments can get compromised due to changes to their viscoelastic material properties. Currently there are discrepancies in the literature on the viscoelastic characteristics of knee ligaments which are thought to be due to tissue variability and different testing protocols. The aim of this study was to characterise the viscoelastic properties of healthy cranial cruciate ligaments (CCLs), from the canine knee (stifle) joint, with a focus on the toe region of the stress-strain properties where any alterations in the extracellular matrix which would affect viscoelastic properties would be seen. Six paired CCLs, from skeletally mature and disease-free Staffordshire bull terrier stifle joints were retrieved as a femur-CCL-tibia complex and mechanically tested under uniaxial cyclic loading up to 10 N at three strain rates, namely 0.1, 1 and 10 %/min, to assess the viscoelastic property of strain rate dependency. The effect of strain history was also investigated by subjecting contralateral CCLs to an ascending (0.1, 1 and 10 %/min) or descending (10, 1 and 0.1 %/min) strain rate protocol. The differences between strain rates were not statistically significant. However, hysteresis and recovery of ligament lengths showed some dependency on strain rate. Only hysteresis was affected by the test protocol and lower strain rates resulted in higher hysteresis and lower recovery. These findings could be explained by the slow process of uncrimping of collagen fibres and the contribution of proteoglycans in the ligament extracellular matrix to intra-fibrillar gliding, which results in more tissue elongations and higher energy dissipation. This study further expands our understanding of canine CCL behaviour, providing data for material models of femur-CCL-tibia complexes, and demonstrating the challenges for engineering complex biomaterials such as knee joint ligaments.

bioengineering↗

bioRxiv2020

Scleraxis is required for the growth of adult tendons in response to mechanical loading

Scleraxis is a basic helix-loop-helix transcription factor that plays a central role in promoting tenocyte proliferation and matrix synthesis during embryonic tendon development. However, the role of scleraxis in the growth and adaptation of adult tendons is not known. We hypothesized that scleraxis is required for tendon growth in response to mechanical loading, and that scleraxis promotes the specification of progenitor cells into tenocytes. We conditionally deleted scleraxis in adult mice using a tamoxifen-inducible Cre-recombinase expressed from the Rosa26 locus (Scx{Delta}), and then induced tendon growth in Scx+ and Scx{Delta} adult mice via plantaris tendon mechanical overload. Compared to the wild type Scx+ group, Scx{Delta} mice demonstrated blunted tendon growth. Transcriptional and proteomic analyses revealed significant reductions in cell proliferation, protein synthesis, and extracellular matrix genes and proteins. Our results indicate that scleraxis is required for mechanically-stimulated adult tendon growth by causing the commitment of CD146+ pericytes into the tenogenic lineage, and by promoting the initial expansion of newly committed tenocytes and the production of extracellular matrix proteins.

cell biology↗

bioRxiv2020

The effect of exercise on the protein profile of rat knee joint intra- and extra-articular ligaments

Injuries to the intra-articular knee joint ligament (anterior cruciate ligament (ACL)) together with the extra-articular medial collateral ligament (MCL) result in significant joint instability, pain and immobility for the affected individual. Moderate endurance type exercise has been shown to increase ligament strength, however little is known on the effect of short-term high intensity exercise regimes such as treadmill training on the ACL and MCL and whether they may be beneficial to the extracellular matrix (ECM) structure of these ligaments. This study aimed to identify the effect of short-term high intensity exercise on the proteome of the rat ACL and MCL using mass spectrometry. Sprague Dawley male rats (n=12) were split into equal groups of control and exercise animals, which were subjected to high intensity training and followed by proteomic analysis of the ACL and MCL. Knee joint and ligament health was assessed using OARSI scoring or using a validated histological scoring system. Histopathological analyses demonstrated no significant changes in the ACL, MCL or cartilage of the knee joint, indicating that the exercise regime used in this study did not have substantial impact on tissue structure and health of several tissues within the rat knee joint. Some proteins were found to be significantly more abundant in the ACL in the exercised group than the control group. However, no proteins with a significantly different expression were identified between MCL control and MCL exercised groups. The majority of proteins expressed at higher levels in the ACL exercise group were cytoskeletal proteins, ribosomal proteins and enzymes. Several matrisomal proteins were also more abundant such as collagen proteins and proteoglycans in ACL exercise group. In conclusion, our results indicate that short-term high intensity exercise has an impact on ACL ECM protein expression, with the majority of differential expressed proteins being cellular proteins such as actins, ribosomal and heat shock proteins, indicative of metabolic and molecular responses. Further study is necessary to determine the impact of these short-term changes on ligament structure and function.

molecular biology↗

bioRxiv2019

Meniscal and ligament modifications in spontaneous and post-traumatic mouse models of osteoarthritis

Osteoarthritis (OA) is a whole joint disease that affects all joint tissues, with changes in the articular cartilage (AC), subchondral bone and synovium. Pathologies in menisci and ligaments, however, are rarely analysed, although both are known to play vital roles in the mechanical stability of the joint. The aim of our study was to describe the pathological changes in menisci and ligament during disease development in murine spontaneous and post-traumatic surgically-induced OA and to quantify tissue mineralisation in the joint space using {micro}CT imaging during OA progression. Knees of Str/ort mice (spontaneous OA model; 26-40wks) and C57CBA F1 mice following destabilisation of medial meniscus (DMM) surgery (post-traumatic OA model; 8wks after DMM), were used to assess histological meniscal and ligament pathologies. Joint space mineralised tissue volume was quantified by {micro}CT. Meniscal pathological changes in Str/ort mouse knees were associated with articular cartilage lesion severity. These meniscal changes included ossification, hyperplasia, cell hypertrophy, collagen type II deposition and SOX9 expression in the fibrous region near the attachment to the knee joint capsule. Anterior cruciate ligaments exhibited extracellular matrix changes and chondrogenesis particularly at the tibial attachment site, and ossification was seen in collateral ligaments. Similar changes were confirmed in the post-traumatic DMM model. {micro}CT analysis showed increased joint space mineralised tissue volume with OA progression in both the post-traumatic and spontaneous OA models. Modifications in meniscal and ligament mineralisation and chondrogenesis are seen with overt AC degeneration in murine OA. Although the aetiology and the consequences of such changes remain unknown, they will influence stability and load transmission of the joint and may therefore contribute to OA progression. In addition, these changes may have important roles in movement restriction and pain, which represent major human clinical symptoms of OA. Description of such soft tissue changes, in addition to AC degradation, should be an important aspect of future studies in mouse models in order to furnish a more complete understanding of OA pathogenesis. Summary statementThis manuscript describes histological changes in mouse knee joints in two models of osteoarthritis and correlates joint space mineralised tissue volume measured by {micro}CT with disease severity.

pathology↗

bioRxiv2019

Evaluating Muscle Fiber Contractility and the Transcriptome, Proteome, Metabolome, and Lipidome of the mdx/mTR Mouse Model of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disease characterized by extensive muscle weakness. Patients with DMD lack a functional dystrophin protein, which transmits force and organizes the cytoskeleton of skeletal muscle. Multiomic studies evaluate combined changes in the transcriptome, proteome, and metabolome, and have been proposed as a way to obtain novel insight about disease processes from preclinical models. We therefore sought to use this approach to study pathological changes in dystrophic muscles. We evaluated hindlimb muscles of male mdx/mTR mice, which lack a functional dystrophin protein and have deficits in satellite cell abundance and proliferative capacity. Wild type (WT) C57BL/6J mice served as controls. Muscle fiber contractility was measured, along with changes in the transcriptome using RNA sequencing, and in the proteome, metabolome, and lipidome using mass spectroscopy. While mdx/mTR mice displayed gross pathological changes and continued cycles of degeneration and regeneration, we found no differences in fiber contractility between strains. However, there were numerous changes in the transcriptome and proteome related to protein balance, contractile elements, extracellular matrix, and metabolism. There was only a 53% agreement in fold change data between the proteome and transcriptome, highlighting the need to study protein abundance along with gene expression measures. Numerous changes in markers of skeletal muscle metabolism were observed, with dystrophic muscles exhibiting elevated glycolytic metabolites. These findings highlight the utility of multiomics in studying muscle disease, and provide additional insight into the pathological changes in dystrophic muscles that might help to guide evidence-based exercise prescription in DMD patients.

physiology↗