Abstract. OBJECTIVE. Changes in subchondral bone are one of few disease characteristics to correlate with pain in OA. 1. Profound neuroplasticity and nociceptor sprouting is displayed within osteoarthritic (OA) subchondral bone and is associated with pain and pathology. 2. The cause of these neural changes remains unestablished. Correct innervation patterns are indispensable for bone growth, homeostasis, and repair. Axon guidance signalling factor, Sema3A is essential for the correct innervation patterning of bony tissues. 3. , expressed in osteocytes. 4. and known to be downregulated in bone OA
Summary Statement. An organ culture experiment was simulated to explore the mechanisms that can link cell death to mechanical overload in the intervertebral disc. Coupling cell nutrition and tissue deformations led to altered metabolic transport that largely explained cell viability measurements. Introduction. Part of intervertebral disc (IVD) maintenance relies on limited nutrient availability to the cells and on
Osteoarthritis (OA) is a common cause of chronic pain. Subchondral bone is highly innervated, and bone structural changes directly correlate with pain in OA. Mechanisms underlying skeletal–neural interactions are under-investigated. Bone derived axon guidance molecules are known to regulate bone remodelling. Such signals in the nervous system regulate neural plasticity, branching and neural inflammation. Perturbation of these signals during OA disease progression may disrupt sensory afferents activity, affecting tissue integrity, nociception, and proprioception. Osteocyte
Abstract. Objectives. Prediction of bone adaptation in response to
Introduction. Within articular cartilage, chondrocytes reside within the pericellular matrix (PCM), collectively constituting the microanatomical entity known as a chondron. The PCM functions as a pivotal protective shield and mediator of biomechanical and biochemical cues. In the context of Osteoarthritis (OA), enzymatic degradation of the PCM is facilitated by matrix metalloproteinases (MMPs). This study delves into the functional implications of PCM structural integrity decline on the biomechanical properties of chondrons and impact on Ca. 2+. signaling dynamics. Method. Chondrons isolated from human cartilage explants were incubated with activated MMP-2, -3, or -7. Structural degradation of the pericellular matrix (PCM) was assessed by immunolabelling (collagen type VI and perlecan, n=5). Biomechanical properties of chondrons (i.e. elastic modulus (EM)) were analyzed using atomic force microscopy (AFM). A fluorescent calcium indicator (Fluo-4-AM) was used to record and quantify the intracellular Ca. 2+. influx of chondrons subjected to single cell
Stimulation of the mechanosensitive ion channel, Piezo1 promotes bone anabolism and SNPs in the Piezo1 locus are associated with changes in fracture risk. Osteocytes function as critical regulators of bone homeostasis by sensing mechanical signals. The current study used a human, cell-based physiological, 3D in vitro model of bone to determine whether loading of osteocytes in vitro results in upregulation of the Piezo1 pathway. Human Y201 MSCs, embedded in type I collagen gels and differentiated to osteocytes for 7-days, were subjected to pathophysiological load (5000 µstrain, 10Hz, 5 mins; n=6) with unloaded cells as controls (n=4). RNA was extracted 1-hr post load and assessed by RNAseq analysis. To mimic
Abstract. Objectives. The aim of this study was to investigate whether
Abstract. INTRODUCTION. The mechanisms underlying abnormal joint mechanics are poorly understood despite it being a major risk factor for developing osteoarthritis. Glutamate signalling has been implicated in osteoarthritic bone changes and AMPA/kainate glutamate receptor (GluR) antagonists alleviate degeneration in rodent models of osteoarthritis. We investigated whether glutamate signalling molecules are mechanically regulated in a human, cell-based 3D model of bone. METHODS. Human Y201 MSC cells embedded in 3D type I collagen gels (0.05 × 106 cell/gel) differentiated to osteocytes were mechanically loaded in silicone plates (5000 µstrain, 10Hz, 3000 cycles) or not loaded (n=5/group). RNA extracted 1-hr post load was quantified by RTqPCR and RNAseq whole transcriptome analysis (NovaSeq S1 flow cell 2 × 100bp PE reads). Differentially expressed GluRs and glutamate transporters (GluTs) were identified using DEseq2 analysis on normalised count data. Genes were considered differentially expressed if >2 fold change and FDR p<0.05. RESULTS. Cells expressed mature osteocyte markers (E11, sclerostin, DMP-1). DEseq2 analysis, revealed 981 mechanically regulated genes.
In a healthy joint,
It is well known that environmental cues such as
Abstract. Objectives. The mechanisms underlying abnormal joint mechanics are poorly understood despite it being a major risk factor for developing osteoarthritis. This study investigated the response of a 3D in vitro bone cell model to
Abstract. Objectives. Unicompartmental and total knee arthroplasty (UKA and TKA) are successful treatments for osteoarthritis, but monolithic implants disrupt the natural homeostasis of bone which leads to bone loss over time. This can cause problems if the implant needs to be revised. This study aimed to demonstrate that tibial implants made from titanium lattice could replace the tibial condyle surface while minimising disruption of the bone's natural
Abstract. Objectives. Osteocytes function as critical regulators of bone homeostasis by sensing mechanical signals. Stimulation of the mechanosensitive ion channel, Piezo1 promotes bone anabolism and deletion of Piezo1 in osteoblasts and osteocytes decreases bone mass and bone strength in mice. This study determined whether loading of osteocytes in vitro results in upregulation of the Piezo1 pathway. Methods. Human MSC cells (Y201), embedded in type I collagen gels and differentiated to osteocytes in osteogenic media for 7-days, were subjected to pathophysiological load (5000 µstrain, 10Hz, 5 mins; n=6) with unloaded cells as controls (n=4). RNA was extracted 1-hr post load and Piezo1 activation assessed by RNAseq analysis (NovaSeq S1 flow cell 2 × 100bp PE reads). To mimic
Osteoarthritis (OA) is the most common joint disease, which is characterized by a progressive loss of proteoglycans and the destruction of extracellular matrix (ECM), leading to a loss of cartilage integrity and joint function. During OA development, chondrocytes alter ECM synthesis and change their gene expression profile including upregulation of hypertrophic markers known from the growth plate. Although physiological
Tendinopathy is a disease associated with pain and tendon degeneration, leading to a decreased range of motion and an increased risk of tendon rupture. The etiology of this frequent disease is still unknown. In other musculoskeletal tissues like cartilage and intervertebral discs, transient receptor potential channels (TRP- channels) were shown to play a major role in the progression of degeneration. Due to their responsiveness to a wide range of stimuli like temperature, pH, osmolarity and
Articulating cartilage experiences a multitude of biophysical cues. Due to its primary function in distributing load with near frictionless articulation, it is clear that a major stimulus for cartilage homeostasis and regeneration is the
Regulation of articular cartilage homeostasis is a complex process in which biologic and mechanical factors are involved. Hyperactivation of Wnt signaling, associated with osteoarthritis (OA), could jeopardize the protective anabolic effect of physiological loading. Here, we investigated the role of excessive Wnt signalling in cartilage molecular responses to loading. Human cartilage explants were harvested from hips of donors without OA. The Wnt agonist CHIR99021 was used to activate Wnt signalling 24 hours before cartilage explants were subjected to a loading protocol consisting of 2 cycles of 1 hour of 10% compression at 1 Hz, followed by 1-hour free swelling. Mechano-responsiveness was evaluated using the expression of type II collagen, aggrecan and MMP-13. Expression of known target genes TCF-1 and c-JUN was evaluated as positive control for Wnt and mechanical stimulation, respectively. In the absence of loading, CHIR99021 decreased the expression of the cartilage anabolic genes type II collagen and aggrecan, and increased the levels of MMP-13, corroborating that Wnt hyperactivation disrupts cartilage homeostasis. In the absence of Wnt hyperactivation, the applied loading protocol, representative for a physiologic stimulation by