Biology subjects

Ramos-Mucci, L.

Publications and source records attributed to Ramos-Mucci, L..

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↗

bioRxiv2025

Fibroblast specialisation across microanatomy in a single-cell atlas of healthy human Achilles tendon

Tendons are transitional tissues linking muscle to bone, enabling locomotion and fine motor control. The cellular biology across the Achilles tendon unit is poorly understood, yet critical for interpreting normal function and pathological changes across its microanatomically-defined functional zones. We generated a spatially-resolved transcriptomic atlas of human Achilles tendon, sampling the tendon-bone junction (enthesis), midbody, myotendinous junction, and adjoining muscle. Six fibroblast subtypes were identified, with distinct transcriptional profiles and spatial distributions, suggesting specialised functional roles across the tendon-muscle unit. Two dominant fibroblast types were specifically positioned in the tendon mid-substance and paratenon (vessel-rich region surrounding the tendon fibrils); other populations included perineural, myotendinous junction-specific, muscle-specific, and lining-layer fibroblasts. These findings demonstrate how cellular diversity across a transitional tissue may underlie microanatomical-specific roles. This atlas provides a foundation for understanding cellular functions across the tendon-muscle unit and will be essential for comparisons with diseased tissue, identifying pathogenic mediators and treatment targets for autoimmune and degenerative pathologies of the Achilles tendon.

genomics↗

bioRxiv2025

Cellular and molecular landscapes of human tendons across the lifespan revealed by spatial and single-cell transcriptomics

Tendon injuries are common and often heal poorly. While developing tendons heal without scarring, this capacity declines with age, yet the underlying cellular transitions remain poorly defined. Here, we integrate histological, single-nucleus, single-cell, and spatial transcriptomic profiling of human Achilles and quadriceps tendons across embryonic, foetal, and adult stages, including ruptured adult tendons. We identify seven embryonic progenitor states that give rise to three distinct tendon-associated fibrillar, connective tissue, and chondrogenic lineages. These populations diversify during development and occupy distinct spatial niches, adopting specialised roles in matrix synthesis, tissue remodelling, and mechanical adaptation. While non-fibroblast populations remain transcriptionally stable with age, fibroblasts undergo marked reprogramming, shifting to homeostatic or injury-responsive states. In ruptured adult tendons, a subset of fibroblasts partially reactivates developmental programs but remains transcriptionally distinct from their regenerative counterparts. These findings define the cellular architecture of human tendon development and ageing and reveal lineage-specific targets for therapeutic repair.

cell biology↗

bioRxiv2024

Exploring cellular changes in ruptured human quadriceps tendons at single-cell resolution

Tendon ruptures in humans have regularly been studied during the chronic phase of injury. However, the early response to injury remains less investigated. Quadriceps tendons, which require prompt surgical treatment, offer a model to investigate this early response. Therefore, this study aimed to explore the early cellular changes in ruptured compared to healthy human quadriceps tendons. Quadriceps tendon samples were collected from patients undergoing tibial shaft fracture repair (healthy) or tendon repair surgery for complete rupture (collected 7-8 days post-injury). Nuclei were isolated for single-nucleus RNA sequencing, and comprehensive transcriptomic analysis was conducted to profile cellular changes. The transcriptomes of 12,808 nuclei were profiled, including 7,268 nuclei from healthy and 5,540 nuclei from ruptured quadriceps tendons, revealing 12 major cell types and several cell subtypes and states. Rupture samples showed increased expression of genes related to extracellular matrix organisation and cell cycle signalling, and a decrease in expression of genes in lipid metabolism pathways. These changes were driven predominantly by gene expression changes in the fibroblast, vascular endothelial cells (VECs), mural cell, and macrophage populations: fibroblasts shift to an activated phenotype upon rupture and there is an increase in proportion of capillary and dividing VECs, suggesting an angiogenic response. A diverse immune environment was observed, with a shift from homeostatic to activated macrophages following rupture. Cell-cell interactions increased in rupture, both in their number and diversity, and primarily involving fibroblast and endothelial cell populations. Collectively, this transcriptomic analysis suggests that fibroblasts and endothelial cells are key orchestrators of the early injury response within ruptured quadriceps tendon.

genomics↗

bioRxiv2024

Sex specific knee joint soft tissue mineralization with Fibrillin-1 mutation in male Tight Skin mice.

Articular soft tissue mineralization and ossification are clear pathological signs of osteoarthritis joints. However their molecular and cellular aetiologies remain largely unknown. TGF-{beta} family members are known contributors to both pathological ossification and osteoarthritis development. In this study, we used a Fibrillin-1 mutant mouse, the Tight Skin mouse (TSK), to define the detrimental effects of abnormal Fbn1 in TSK mice and known high TGF-{beta} activity in joint pathology such as articular soft tissue mineralization and ossification. Knee joints of male and Female TSK and Wild-type (WT) littermates were analysed my micro-CT imaging and histology for articular soft tissue pathologies, as well as OA severity. Both aged (10, 26, 35 and 52wks) and following in vivo non-invasive repetitive joint overloading were used. We find that male TSK mice develop spontaneous soft tissue ossification from 26wks of age, followed by increased osteoarthritis at 1 year-old. In addition, knee joint overloading induced ligament and meniscal mineralisation and ossification in both WT and TSK male mice, but were significantly more severe in TSK knees, including ossification of the patella ligament and synovial lining. In contrast, female TSK knees did not develop more severe soft tissue mineralisation compared to littermate WT mice in neither aged nor overloaded knees. We conclude that Fbn1 mutation, and possibly overactive TGF-{beta} activity in TSK mice, induce articular soft tissue ossification and osteoarthritis in a sex-specific manner. Further studies are needed to confirm the specific signalling involved and the relative protection from female mice from such pathologies.

pathology↗

bioRxiv2022

DeepsmirUD: Precise prediction of regulatory effects on miRNA expression mediated by small molecular compounds using competing deep learning frameworks

Aberrant miRNA expression has pervasively been found to relate to a growing number of human diseases. Therefore, targeting miRNAs to regulate their expression levels has become an important therapy against diseases that stem from the dysfunction of oncogenic pathways regulated by the miRNAs. In recent years, small molecule compounds have demonstrated enormous potential as drugs to regulate miRNA expression (i.e., SM-miR). A clear understanding of the mechanism of action of small molecules on down- and up-regulating miRNA expression allows precise diagnosis and treatment of oncogenic pathways. However, outside of a slow and costly process of experimental determination, computational strategies to assist this in an ad hoc manner have still not been enabled. In this work, we develop, to the best of our knowledge, the first prediction tool, DeepsmirUD, to infer small molecule-mediated regulatory effects on miRNA expression. This method is powered by an ensemble of 12 cutting-edged deep learning frameworks and achieves state-of-the-art performance with AUC values of 0.840/0.969 and AUCPR values of 0.866/0.983 on two independent test datasets. With a complementarily constructed network inference approach based on similarity, we report a significantly improved accuracy of 0.813 in determining regulatory effects of nearly 650 SM-miR relations formed with either novel small molecules or novel miRNAs. By further integrating miRNA-cancer relations, we established a database of potentially pharmaceutical drugs to aid in understanding the drug mechanisms of action in diseases and to offer novel insight into drug repositioning. Taken together, our method shows great promise to assist and accelerate the therapeutic development of potential miRNA targets and small molecule drugs. Furthermore, we have employed DeepsmirUD to predict regulatory effects of a large number of high-confidence SM-miR relations curated from Psmir, which are publicly available through https://github.com/2003100127/deepsmirud and https://rujinlong.github.io/deepsmirud/ alongside the DeepsmirUD standalone package.

bioinformatics↗

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

Post-traumatic osteoarthritis development is not modified by postnatal chondrocyte deletion of CCN2.

CCN2 is a matricellular protein involved in several critical biological processes. In particular, CCN2 is involved in cartilage development and in osteoarthritis. CCN2 null mice exhibit a range of skeletal dysmorphisms, highlighting its importance in regulating matrix formation during development, however its role in adult cartilage remains unclear. The aim of this study was to determine the role of CCN2 in postnatal chondrocytes in models of post-traumatic osteoarthritis (PTOA). CCN2 deletion was induced in articular chondrocytes of male transgenic mice at 8 weeks of age. PTOA was induced in knees either surgically or non-invasively by repetitive mechanical loading at 10 weeks of age. Knee joints were harvested, scanned with micro-CT, and processed for histology. Sections were stained with toluidine blue and scored using the OARSI grading system. In the non-invasive model cartilage lesions were present in the lateral femur but no significant differences were observed between wildtype (WT) and CCN2 knockout (KO) mice 6 weeks post-loading. In the surgical model, severe cartilage degeneration was observed in the medial compartments but no significant differences were observed between WT and CCN2 KO mice at 2, 4, and 8 weeks post-surgery. We conclude that CCN2 deletion in chondrocytes did not modify the development of PTOA in mice, suggesting that chondrocyte expression of CCN2 in adults is not a critical player in protecting cartilage from the degeneration associated with PTOA. Summary StatementPost-natal deletion of CCN2 in chondrocytes does not affect the development of post-traumatic osteoarthritis in mice.

pathology↗

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↗