Connective Tissue Research最新文献

Osteoarthritis (OA) is a multifactorial, mechano-inflammatory joint disorder characterized by cartilage degradation, synovial inflammation, and subchondral bone remodeling. Despite its high prevalence and significant impact on quality of life, no disease-modifying treatments have been approved. In many other disease areas, advanced omics technologies are impacting the development of advanced therapies. In OA, omics technologies such as genomics, transcriptomics, proteomics, and metabolomics have significantly increased our understanding of OA pathogenesis by uncovering molecular pathways driving disease progression. However, we have yet to see any tangible impact on the development of effective disease-modifying therapies. This review focuses on single- and multi-omics studies in OA, emphasizing their role in identifying molecular subtypes (endotypes) and therapeutic subtypes (theratypes). Multi-omics integration has revealed crosstalk between inflammatory, metabolic, and degradative processes, while spatial proteomics is beginning to provide insights into synovial tissue heterogeneity. However, challenges such as data complexity, lack of standardized frameworks, and limited translational validation hinder rapid progress. Future work will need to leverage artificial intelligence, single-cell, and spatial omics within longitudinal cohort studies. By addressing these challenges, omics-driven research holds promise for helping clinicians differentiating patients presenting with OA and psoriatic arthritis (PsA) affecting the hands or knees, developing personalized OA therapies, and achieving true disease modification beyond symptomatic relief.

Injury of the anterior cruciate ligament (ACL) is a common sports injury that can lead to post-traumatic osteoarthritis (PTOA) within 10-20 years. Surgical ACL reconstruction is often performed several weeks or months after injury, and this period between injury and ACL reconstruction may be a critical time for determining the risk of long-term PTOA progression. However, few (if any) studies in human patients have investigated the long-term effects of exercise or unloading between ACL injury and surgery. Early mobilization is often recommended to maintain range of motion and muscle strength, which are beneficial for positive outcomes of ACL reconstruction, but it is unknown what effects early mobilization or unloading have on long-term PTOA progression. In preclinical animal studies, a brief period of joint unloading immediately after ACL injury significantly decreased osteophyte formation and articular cartilage degeneration, while longer-term non-weightbearing caused muscle atrophy and articular cartilage degradation. Similarly, preclinical studies have shown that different intensities of exercise after knee injury can have divergent effects on PTOA development. Low intensity exercise was protective against joint degeneration, while higher intensity exercise accelerated PTOA progression. The beneficial or detrimental effects of exercise and unloading following ACL injury are likely dependent on the timing, duration, and intensity of these biomechanical interventions. This review summarizes the effects of these biomechanical interventions after ACL injury in both humans and animal models, with the goal of informing therapeutic and rehabilitation strategies for slowing or preventing PTOA progression after injury.

This review article examines the application of tissue engineering approaches in the treatment of osteoarthritis (OA), a complex joint disease characterized by tissue crosstalk and inflammation. The article covers preclinical testing platforms, including long-term in vitro studies, ex vivo models with osteochondral explants, and in vivo animal studies. It highlights the advantages and limitations of these models in evaluating tissue-engineered constructs for OA repair and focusses on cartilage specific treatments and resurfacing. The review also explores focal damage approaches such as autologous cultured chondrocytes and Autologous Matrix-Induced Chondrogenesis, which have shown improved patient outcomes. Additionally, it discusses natural and synthetic biomaterials used in cartilage repair, emphasizing the need for combining materials to enhance therapeutic efficacy. The importance of long-term studies in large animal models is underscored to develop effective strategies for cartilage repair. This minireview explores various approaches aimed at effectively addressing and repairing cartilage damage, covering preclinical testing platforms, cartilage resurfacing methods, and tissue engineering (TE) clinical trials. It also highlights challenges in developing future cartilage repair therapies.

Epigenetic mechanisms are implicated in osteoarthritis (OA) as they regulate the expression of several key genes involved in OA disease progression. This mini-review highlights major epigenetic studies in OA from the past 25 years, focusing on mechanistic and therapeutic perspectives. We discuss how DNA methylation, histone modifications, and non-coding RNAs (ncRNAs) impact OA, highlighting preclinical studies targeting epigenetic mechanisms in mouse models. Indeed, existing studies demonstrate that DNA methylation regulates the expression of OA-related genes through DNA methyltransferases, and targeting their activity has shown promise in restoring cartilage homeostasis. EZH2 and DOT1L are key methyltransferases involved in histone methylation with opposing roles in OA: high EZH2 promotes disease progression and is a potential therapeutic target, whereas DOT1L exerts protective effects, partly by suppressing Wnt signaling. Additionally, targeting enzymes that catalyze histone acetylation (PCAF, BRD4) and deacetylation (HDAC1/2) has demonstrated therapeutic potential in preclinical OA models. ncRNAs-including miRNAs, circRNAs, and lncRNAs-regulate gene expression in OA tissues at multiple levels. Several miRNAs (e.g. miR-17, miR-27b-3p) influence cartilage homeostasis and OA pathogenesis, while circRNAs (e.g. circPDE4B) and lncRNAs (e.g. ELDR) have emerged as important disease regulators, offering new therapeutic avenues. Despite significant advancements in OA-related epigenetic mechanisms, clinical translation remains challenging due to the complexity of epigenetic regulation, patient heterogeneity, and limited success of preclinical studies. Importantly, epigenetic alterations are often context-specific, necessitating nuanced interpretation to accurately discern their role in OA. Future research should prioritize identifying specific epigenetic markers linked to clinical outcomes (e.g. structural changes, functional impairment, pain) and developing more selective and potent epigenetic modulators for therapeutic use.

Obesity is a major risk factor for osteoarthritis (OA), yet the precise contribution to the pathogenesis of OA is still not fully known. Although traditionally viewed as a weight-induced joint deterioration, recent studies have highlighted multiple mechanisms through which obesity contributes to OA. This review summarizes the advances in our understanding of the obesity-associated impact on OA and addresses the knowledge gaps within the field. It highlights the newest findings on the role of local and systemic factors produced by adipose tissue (AT). While AT-derived adipokines, such as leptin and resistin, have been shown to promote cartilage degradation by inducing pro-inflammatory cytokines through multiple pathways, others, like adiponectin, exert both pro- and anti-inflammatory effects. Furthermore, this review focuses on recent findings regarding the reorganization of the obesity-associated immune cell landscape during OA progression, highlighting the reduced content of synovial lining macrophages and patrolling monocytes, as well as the increased content of monocyte-derived macrophages, T cells, and myeloid suppressor cells in obese subjects. Additionally, this review explores the emerging link between the gut microbiome and metabolic dysfunction in obesity-related OA and examines the influence of sex differences on the disease. By framing OA as a systemic condition in the context of obesity, this review underscores the need for multifactorial therapeutic approaches and precision medicine strategies to address this growing public health challenge. By presenting current and emerging treatment strategies, this review features the multifaceted approach to managing and researching OA in obese populations, emphasizing the need for innovative preventative measures.

Osteoarthritis (OA) is the most common musculoskeletal-related disease affecting over 27 million US adults, and no disease-modifying agents are currently available. Signs of bone remodeling are a major hallmark of OA, and include subchondral sclerosis (seen on x-ray), subchondral bone marrow lesions (seen on MRI), and osteophytosis. Recent work suggests subchondral bone remodeling is likely a driver of pain in OA. In this review, we seek to provide an overview on what is known about the cellular and molecular mechanisms that play a role in osteoarthritic subchondral bone remodeling and associated pain. Searching for "subchondral bone remodeling" "pain" and "osteoarthritis," we reviewed publications from 2015 onward. We found new details of how osteoblasts, osteoclasts, and osteocytes communicate in both autocrine and paracrine manners in OA, allowing identification of potential candidates that play a role in the aberrant bone remodeling seen in OA. Furthermore, there is new knowledge regarding mechanisms of how bone cells communicate with nociceptive neurons, providing potential candidates to target for treatment of OA pain. Recent clinical trials targeting OA-associated bone remodeling have been published with some encouraging results. In the future, more work is necessary to understand the inciting events that lead to the pathogenic cell behaviors, and unravel the complex cellular communication detailed in this review. In addition, efforts to understand the discordant results from recent trials of existing agents targeting bone remodeling and to develop novel bone-targeted agents for OA are needed.

Osteoarthritis (OA), long regarded as simply a disease of articular cartilage degeneration, has increasingly been recognized as a complex disorder involving multiple joint tissues, including the synovium. This review explores the emerging evidence that synovial changes seen in OA are not merely secondary to cartilage breakdown but may actively drive OA progression. We detail the physiological role of the synovium in joint homeostasis and highlight pathological remodeling processes, such as synovial hyperplasia, immune cell infiltration, and fibroblast activation, that contribute to joint degeneration. Mechanistic insights implicate fibroblast-like synoviocytes and synovial macrophages in initiating and perpetuating inflammatory and catabolic cascades that alter synovial fluid composition, impair cartilage integrity, and exacerbate disease symptoms. Clinical and preclinical data increasingly link synovitis and synovial damage to structural disease progression and pain, underscoring their prognostic and therapeutic significance. Despite promising targets, effective disease-modifying therapies remain elusive due to the molecular complexity and clinical heterogeneity of the disease and limitations in early diagnostic evaluations. To overcome this, innovative research methods, improved diagnostic tools, and interdisciplinary collaboration will be critical. Collectively, this work advocates for a paradigm shift that the synovium is a central player in OA pathogenesis and a viable target for therapeutic intervention.

Synovial joints are complex multi-tissue organs that permit movement. A well-functioning synovial joint relies on complex interconnected homeostatic mechanisms to maintain joint organ function in response to biomechanical and metabolic demands. These homeostatic mechanisms include, but are not limited to, appropriate mechanobiological responses to load, nutrient delivery from its vasculature, lubrication, proprioception and pain, immunosurveillance, and maintenance of the extracellular matrix (ECM) composition. In osteoarthritis (OA), joint homeostasis is chronically deranged leading to failure of the synovial joint organ and impairment or loss of function. Maintaining synovial joint organ homeostasis is therefore critical to joint function and relies on complex interconnected physiological process at the joint level. As OA prevalence continues to rise, deepening our understanding of the integrated systems that sustain joint homeostasis may identify fruitful avenues for therapeutic intervention. However, key knowledge gaps will need to be addressed including, characterizing vessel function in joint diseases, understanding the role of novel proteases in ECM catabolism, and determining the role of non-macrophage synovial immune cells in joint immunosurveillance. We believe that future research will find greater success if these homeostatic mechanisms are viewed as a single integrated system that considers the crosstalk between mechanical, vascular, immune, and biochemical factors. Therefore, in this review, we explore the interconnected mechanisms that support joint homeostasis and how dysregulation can lead to failure of the synovial joint organ.

Oxygen availability plays a critical role in maintaining cartilage homeostasis and influencing the progression of osteoarthritis (OA). Articular cartilage is an avascular tissue that depends on a tightly regulated hypoxic microenvironment, with oxygen gradients shaped by diffusion from synovial fluid, cartilage thickness, and mechanical loading. Both degenerative OA, which develops gradually with age, and post-traumatic osteoarthritis (PTOA), which follows joint injury and progresses more rapidly, may involve disruption of this oxygen balance. Such dysregulation, whether through reduced or elevated oxygen tension, can impair chondrocyte metabolism, increase reactive oxygen species (ROS) production, and alter hypoxia-inducible factor 1-alpha (HIF-1α) signaling, ultimately contributing to cartilage degeneration. This mini-review explores the complex oxygen dynamics in cartilage and their potential role in OA. We highlight current knowledge gaps in oxygen level assessment and mechanistic understanding, and discuss emerging therapeutic and biomaterial-based strategies, including oxygen-sensing nanoparticles, ROS-responsive scaffolds, and oxygen-generating materials, that aim to modulate the joint oxygen environment. These approaches underscore the need for temporally controlled oxygen-related pathway modulation to support cartilage repair. Advancing our understanding of oxygen regulation in joint tissues may offer new opportunities for more effective, stage-specific OA therapies.