Articular Cartilage Proteoglycan Research Articles

The common marmoset as a translational model of age-related osteoarthritis.

Age-related osteoarthritis (OA) is a degenerative joint disease characterized by pathological changes in nearly every intra- and peri-articular tissue that contributes to disability in older adults. Studying the etiology of age-related OA in humans is difficult due to an unpredictable onset and insidious nature. A barrier in developing OA modifying therapies is the lack of translational models that replicate human joint anatomy and age-related OA progression. The purpose of this study was to determine whether the common marmoset is a faithful model of human age-related knee OA. Semi-quantitative microCTscoring revealed greater radiographic OA in geriatric versus adult marmosets, and the age-related increase in OA prevalence was similar between marmosets and humans. Quantitative assessments indicate greater medial tibial cortical and trabecular bone thickness and heterogeneity in geriatric versus adult marmosets which is consistent with an age-related increase in focal subchondral bone sclerosis. Additionally, marmosets displayed an age-associated increase in synovitis and calcification of the meniscus and patella. Histological OA pathology in the medial tibial plateau was greater in geriatric versus adult marmosets driven by articular cartilage damage, proteoglycan loss, and alteredchondrocyte cellularity. The age-associated increase in medial tibial cartilage OA pathology and meniscal calcification was greater in female versus male geriatric marmosets. Overall, marmosets largely replicate human OA as evident by similar 1) cartilage and skeletal morphology, 2) age-related progression in OA pathology, and 3) sex differences in OA pathology with increasing age. Collectively, these data suggest that the common marmoset is a highly translatable model ofthe naturally occurring, age-related OA seenin humans.

Spatial distribution proteoglycans articular cartilage of femoral condyles and tibial plateau in experimental osteoarthritis in rats

Currently, worldwide research is being conducted on the development of new drugs for viscosupplementation therapy. However, there are a very few studies dedicated to the spatial distribution of proteoglycans in articular cartilage after the use of these drugs. Pulmonary surfactant proteins, which have lubricative functions similar to those of articular cartilage proteoglycans, are possible promising substances for viscosupplementation therapy. The aim of this study is to investigate the effect of a mixture of allogenic surfactant proteins (MASP) on the spatial distribution of proteoglycans and the expression of IL-1 in articular cartilage after their intra-articular injection. Morphological and immunohistochemical studies were conducted using antibodies to aggrecan and lubricin to assess the spatial distribution of proteoglycans, and antibodies to IL-1 were used to identify potential pro-inflammatory processes. Three weeks after intra-articular injection of MASP, the thickness of the articular cartilage and the relief of the joint surface did not change compared to intact rats. However, a decrease in the number of immunopositive chondrocytes to aggrecan in the intermediate zone of the articular cartilage and an increase in IL-1 were observed after MASP injection. The obtained data during the study can be used for further research on MASP in the conditions of experimental osteoarthritis.

Cationic tantalum oxide nanoparticle contrast agent for micro computed tomography reveals articular cartilage proteoglycan distribution and collagen architecture alterations

ObjectiveCationic tantalum oxide nanoparticles (Ta2O5-cNPs), as a newly introduced contrast agent for computed tomography (CT) of cartilage, offer quantitative evaluation of proteoglycan content and biomechanical properties. However, knowledge on the depth-wise impact of cartilage constituents on NP diffusion, particularly the influence of the collagen network, is lacking. In this study, we aim to establish the depth-dependent relationship between Ta2O5-cNP diffusion and cartilage constituents (proteoglycan content, collagen content and network architecture). MethodsOsteochondral samples (n = 30) were harvested from healthy equine stifle joints (N = 15) and the diffusion of 2.55 nm diameter cationic Ta2O5-cNPs into the cartilage was followed with µCT imaging for up to 96 hours. The diffusion-related parameters, Ta2O5-cNP maximum partition (Pmax) and diffusion time constant, were compared against biomechanical and depth-wise structural properties. Biomechanics were assessed using a stress-relaxation and sinusoidal loading protocols, whereas proteoglycan content, collagen content and collagen network architecture were determined using digital densitometry, Fourier-transform infrared spectroscopy and polarized light microscopy, respectively. ResultsThe Pmax correlates with the depth-wise distribution of proteoglycans (bulk Spearman’s ρ = 0.87, p < 0.001). More open collagen network architecture at the superficial zone enhances intake of Ta2O5-cNPs, but collagen content overall decreases the intake. The Pmax values correlate with the equilibrium modulus (ρ = 0.80, p < 0.001) of articular cartilage. ConclusionThis study establishes the feasibility of Ta2O5-cNPs for the precise and comprehensive identification of biomechanical and structural changes in articular cartilage via contrast-enhanced µCT.

Effect of glycosaminoglycans on the structure and composition of articular cartilage and bone of broilers

This study aimed to assess the influence of glycosaminoglycan (chondroitin and glucosamine sulfates) supplementation in the diet of broilers on the expression of matrix metallopeptidase 9 (MMP-9) and metallopeptidase inhibitor 2 (TIMP-2) genes, the synthesis of proteoglycans, collagen type II and chondrocytes, bone and cartilage macroscopy, bone mineral densitometry, bone breaking strength and mineral profile. A completely randomized design was carried out in a 3×3 factorial scheme (3 levels of chondroitin sulfate: 0.00, 0.05, and 0.10%; and 3 levels of glucosamine sulfate: 0.00, 0.15, and 0.30%), totaling 9 treatments. At 21 and 42 d of age, broilers were slaughtered, and tibias and femurs were collected for evaluation. There was an interaction (P < 0.05) of sulfates for the expression of MMP-9 and its inhibitor TIMP-2 in femur articular cartilage, as well as for the number of chondrocytes, collagen type II and proteoglycans in tibia articular cartilage, bone and cartilage macroscopy and mineral profile (P < 0.05), with better results obtained with the inclusion of chondroitin and/or glucosamine sulfates in the feed. In conclusion, chondroitin and glucosamine sulfates can be used in broiler diets in order to favor the development of the structure of the locomotor system (bones and joints), thus preventing locomotion problems.

Proteoglycans in Articular Cartilage and Their Contribution to Chondral Injury and Repair Mechanisms.

Proteoglycans are vital components of the extracellular matrix in articular cartilage, providing biomechanical properties crucial for its proper functioning. They are key players in chondral diseases, specifically in the degradation of the extracellular matrix. Evaluating proteoglycan molecules can serve as a biomarker for joint degradation in osteoarthritis patients, as well as assessing the quality of repaired tissue following different treatment strategies for chondral injuries. Despite ongoing research, understanding osteoarthritis and cartilage repair remains unclear, making the identification of key molecules essential for early diagnosis and effective treatment. This review offers an overview of proteoglycans as primary molecules in articular cartilage. It describes the various types of proteoglycans present in both healthy and damaged cartilage, highlighting their roles. Additionally, the review emphasizes the importance of assessing proteoglycans to evaluate the quality of repaired articular tissue. It concludes by providing a visual and narrative description of aggrecan distribution and presence in healthy cartilage. Proteoglycans, such as aggrecan, biglycan, decorin, perlecan, and versican, significantly contribute to maintaining the health of articular cartilage and the cartilage repair process. Therefore, studying these proteoglycans is vital for early diagnosis, evaluating the quality of repaired cartilage, and assessing treatment effectiveness.

Gait Variability Structure Linked to Worse Cartilage Composition Post-ACL Reconstruction.

Aberrant gait variability has been observed after anterior cruciate ligament reconstruction (ACLR), yet it remains unknown if gait variability is associated with early changes in cartilage composition linked to osteoarthritis development. Our purpose was to determine the association between femoral articular cartilage T1ρ magnetic resonance imaging relaxation times and gait variability. T1ρ magnetic resonance imaging and gait kinematics were collected in 22 ACLR participants (13 women; 21 ± 4 yr old; 7.52 ± 1.43 months post-ACLR). Femoral articular cartilage from the ACLR and uninjured limbs were segmented into anterior, central, and posterior regions from the weight-bearing portions of the medial and lateral condyles. Mean T1ρ relaxation times were extracted from each region and interlimb ratios (ILR) were calculated (i.e., ACLR/uninjured limb). Greater T1ρ ILR values were interpreted as less proteoglycan density (worse cartilage composition) in the injured limb compared with the uninjured limb. Knee kinematics were collected at a self-selected comfortable walking speed on a treadmill with an eight-camera three-dimensional motion capture system. Frontal and sagittal plane kinematics were extracted, and sample entropy was used to calculate kinematic variability structure (KV structure ). Pearson's product-moment correlations were conducted to determine the associations between T1ρ and KV structure variables. Lesser frontal plane KV structure was associated with greater mean T1ρ ILR in the anterior lateral ( r = - 0.44, P = 0.04) and anterior medial condyles ( r = - 0.47, P = 0 .03). Lesser sagittal plane KV structure was associated with greater mean T1ρ ILR in the anterior lateral condyle ( r = - 0.47, P = 0.03). The association between less KV structure and worse femoral articular cartilage proteoglycan density suggests a link between less variable knee kinematics and deleterious changes joint tissue changes. The findings suggest that less knee kinematic variability structure is a mechanism linking aberrant gait to early osteoarthritis development.

Bardoxolone methyl ameliorates osteoarthritis by inhibiting osteoclastogenesis and protecting the extracellular matrix against degradation

Inflammation and oxidative damage are closely related to the development of osteoarthritis. Bardoxolone methyl (CDDO-Me), a semisynthetic oleanane triterpenoid, plays a strong anti-inflammatory and antioxidant role. The purpose of our research was to explore fundamental mechanisms of CDDO-Me in orthopaedics development. The results showed that CDDO-Me inhibited nuclear factor-κB ligand (RANKL)-induced osteoclast formation and extracellular matrix (ECM) degradation by activating the Nrf2/HO-1 signaling pathways and inhibiting NF-κB pathway activation and excess ROS production. In vivo, CDDO-Me significantly attenuated articular cartilage proteoglycan loss and the number of TRAP-positive osteoclasts in a destabilized medial meniscus (DMM) mouse model of OA. Taken together, these data demonstrate that CDDO-Me inhibits osteoclastogenesis and ECM degradation, underscoring its potential therapeutic value in treating OA.

Early removal of the infrapatellar fat pad/synovium complex beneficially alters the pathogenesis of moderate stage idiopathic knee osteoarthritis in male Dunkin Hartley guinea pigs

BackgroundThe infrapatellar fat pad (IFP) is the largest adipose deposit in the knee; however, its contributions to the homeostasis of this organ remain undefined. To determine the influence of the IFP and its associated synovium (IFP/synovium complex or IFP/SC) on joint health, this study evaluated the progression of osteoarthritis (OA) following excision of this unit in a rodent model of naturally-occurring disease.MethodsMale Dunkin-Hartley guinea pigs (n=18) received surgical removal of the IFP in one knee at 3 months of age; contralateral knees received sham surgery as matched internal controls. Mobility and gait assessments were performed prior to IFP/SC removal and monthly thereafter. Animals were harvested at 7 months of age. Ten set of these knees were processed for microcomputed tomography (microCT), histopathology, transcript expression analyses, and immunohistochemistry (IHC); 8 sets of knees were dedicated to microCT and biomechanical testing (material properties of knee joints tissues and anterior drawer laxity).ResultsFibrous connective tissue (FCT) developed in place of the native adipose depot. Gait demonstrated no significant differences between IFP/SC removal and contralateral hindlimbs. MicroCT OA scores were improved in knees containing the FCT. Quantitatively, IFP/SC-containing knees had more osteophyte development and increased trabecular volume bone mineral density (vBMD) in femora and tibiae. Histopathology confirmed maintenance of articular cartilage structure, proteoglycan content, and chondrocyte cellularity in FCT-containing knees. Transcript analyses revealed decreased expression of adipose-related molecules and select inflammatory mediators in FCTs compared to IFP/SCs. This was verified via IHC for two key inflammatory agents. The medial articular cartilage in knees with native IFP/SCs showed an increase in equilibrium modulus, which correlated with increased amounts of magnesium and phosphorus.Discussion/conclusionFormation of the FCT resulted in reduced OA-associated changes in both bone and cartilage. This benefit may be associated with: a decrease in inflammatory mediators at transcript and protein levels; and/or improved biomechanical properties. Thus, the IFP/SC may play a role in the pathogenesis of knee OA in this strain, with removal prior to disease onset appearing to have short-term benefits.

More Regular Gait Patterns Associate With Worse Femoral Cartilage Composition Following Anterior Cruciate Ligament Reconstruction

Individuals with anterior cruciate ligament reconstruction (ACLR) exhibit more regular gait patterns, resulting in more rigid movements compared to controls. Aberrant joint loading post-ACLR is linked to worse T1ρ magnetic resonance imaging (MRI) relaxation times, an outcome associated with osteoarthritis development. Yet, it remains unknown if knee movement regularity during gait associates with knee cartilage composition in individuals with ACLR. PURPOSE: Determine the association between femoral articular cartilage T1ρ MRI relaxation times and knee joint movement regularity during gait. METHODS: T1ρ MRI and gait kinematics were collected in 20 participants with ACLR (13 Females; 21 ± 4 years old; 8 ± 1 months post-ACLR). Femoral articular cartilage from the ACLR and uninjured limbs was segmented into anterior, central, and posterior regions from the weightbearing portions of the medial and lateral condyles. Mean T1ρ relaxation times were extracted from the cartilage in each region and interlimb ratios were calculated (i.e., ACLR / uninjured limb). Greater interlimb T1ρ ratios were interpreted as lesser proteoglycan density (worse cartilage composition) in the injured limb compared to the uninjured limb. Knee kinematics were collected at a self-selected gait speed on a treadmill with an 8-camera 3D motion capture system. Frontal and sagittal plane knee kinematics were extracted, and sample entropy was used to calculate the degree of movement regularity (i.e., lower values reflect more regularity). Pearson’s product-moment correlations were conducted to determine the association between T1ρ and movement regularity variables. RESULTS: Greater frontal plane knee movement regularity associated with greater mean T1ρ interlimb ratios in the anterior portions of the lateral (r = -0.44, p = .04) and medial condyles (r = -0.47, p = .03). Greater sagittal plane kinematic regularity associated with greater mean T1ρ interlimb ratios in the anterior portion of the lateral condyle (r = -0.47, p = .03). CONCLUSION: Greater movement regularity was associated with less femoral articular cartilage proteoglycan density which is linked to early osteoarthritis development. We hypothesize that greater movement regularity contributes to less adaptable gait and more concentrated cartilage loading.

Pleiotropic effects of diacerein in comorbid patients with osteoarthritis

The article presents an analysis of the therapeutic effect of the drug diacerein (D), which has been used in osteoarthritis (OA) for more than 20 years and is included in the clinical guidelines of the Association of Rheumatologists of Russia (2021) and the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal diseases (ESCEO, 2019) for the treatment of OA. The main pathogenic effect of D in OA is to suppress the synthesis of interleukin 1, stimulate the production of articular cartilage proteoglycans, and slow down abnormal remodeling of the subchondral bone. The advantages of D in the treatment of patients with OA and comorbidities are presented – a prolonged anti-inflammatory and analgesic effect and good tolerability. These properties of D allow to control the symptoms of OA and improve the quality of life of patients. The structure-modifying effect of D is based on its ability to stimulate the synthesis of articular cartilage proteoglycans with long-term use and prevent abnormal remodeling of the subchondral bone, which leads to a decrease in the risk of OA progression and a delay in total joint arthroplasty. An important advantage of D is its positive metabolic effect in patients with type 2 diabetes mellitus and obesity, which is associated with the ability of D to reduce the level of glycated hemoglobin and body mass index. Data are presented on the absence of adverse cardiovascular effects when using D, which allows us to recommend its use in patients with OA who have comorbid cardiovascular diseases, as well as contraindications for non-steroidal anti-inflammatory drugs.

Effect of cells on spatial quantification of proteoglycans in articular cartilage of small animals

ABSTRACT Objective Histochemical characterization of proteoglycan content in articular cartilage is important for the understanding of osteoarthritis pathogenesis. However, cartilage cells may interfere with the measurement of matrix proteoglycan content in small animal models (e.g. mice and rats) due to the high cell volume fraction (38%) in mice compared to human tissue (~1%). We investigated whether excluding the cells from image analysis affects the histochemically measured proteoglycan content of rat knee joint cartilage and assessed the effectiveness of a deep learning algorithm-based tool named U-Net in cell segmentation. Design Histological sections were stained with Safranin-O, after which optical densities were measured using digital densitometry to estimate proteoglycan content. U-Net was trained with 600 annotated Safranin-O cartilage images for exclusion of cells from the cartilage extracellular matrix. Optical densities of the ECM with and without cells were compared as a function of normalized tissue depth. Results U-Net cell segmentation was accurate, with the measured cell area fraction following largely that of ground-truth images (average difference: 4.3%). Cell area fraction varied as a function of tissue depth and took up 8–21% of the tissue area. The exclusion of cells from the analysis led to an increase in the analyzed depth-dependent optical density of cartilage by approximately 0.6–1.8% (p < 0.01). Conclusions Although the effect of cells on the analyzed proteoglycan content is small, it should be considered for improved sensitivity, especially at the onset of the disease during which cells may proliferate in small animals.

Metformin and Resveratrol Suppress Type 2 Diabetes Mellitus-Induced Articular Cartilage Damage in Rats Associated with the Inhibition of Inflammation and Augmentation of Proteoglycans

Induction of osteoarthritis (OA) following diabetes is characterized by a sever inflammation of the joints that can lead to disability. The cartilage content of proteoglycans can substantially be reduced, following the induction of diabetes mellitus associated with inflammation as well as knee joint injury, and the antidiabetic drug metformin combined with the anti-inflammatory agent resveratrol can prevent these deleterious effects. Therefore, insulin-independent diabetes, type 2 diabetes mellitus (T2DM) was induced in Albino rats by streptozotocin (STZ) injection (50 mg/kg) after being fed on a high carbohydrate and fat diets for 2 weeks. The protective group of rats which also received a single injection of STZ was treated daily with metformin (Met; 200 mg/kg) and resveratrol (Res; 30 mg/kg) for 12 weeks. Harvested knee joint tissues were prepared for basic histology stain and for proteoglycans staining using light microscopy. Histology images showed in diabetic rats (T2DM) OA development as demonstrated by profound injury to the knee joint and severe decrease of articular cartilage proteoglycans content, which were substantialy protected by Met+Res. Met+Res also significantly (p< 0.0001) decreased diabetes induced glycemia, dyslipidemia, and the inflammatory biomarkers, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and high sensitivity C-reactive protein (hs-CRP). In addition, there was a significant correlation between OA and glycemia, dyslipidemia, and inflammation. Collectively, we demonstrate an association between knee joint damage and biomarkers of glycemia, dyslipidemia, and inflammation in diabetes-induced OA, with metformin plus resveratrol providing protective effects.

Rapamycin-induced hyperglycemia is associated with exacerbated age-related osteoarthritis

BackgroundThe objective of this study was to determine if mechanistic target of rapamycin (mTOR) inhibition with or without AMP-activated protein kinase (AMPK) activation can protect against primary, age-related OA.DesignDunkin-Hartley guinea pigs develop mild primary OA pathology by 5 months of age that progresses to moderate OA by 8 months of age. At 5 months, guinea pigs served as young control (n = 3) or were fed either a control diet (n = 8), a diet enriched with the mTOR-inhibitor rapamycin (Rap, 14 ppm, n = 8), or Rap with the AMPK-activator metformin (Rap+Met, 1000 ppm, n = 8) for 12 weeks. Knee joints were evaluated by OARSI scoring, micro-computed tomography, and immunohistochemistry. Glenohumeral articular cartilage was collected for western blotting.ResultsRap- and Rap+Met-treated guinea pigs displayed lower body weight than control. Rap and Rap+Met inhibited articular cartilage mTORC1 but not mTORC2 signaling. Rap+Met, but not Rap alone, stimulated AMPK. Despite lower body weight and articular cartilage mTORC1 inhibition, Rap- and Rap+Met-treated guinea pigs had greater OA severity in the medial tibial plateau due to articular cartilage structural damage and/or proteoglycan loss. Rap and Rap+Met increased plasma glucose compared to control. Plasma glucose concentration was positively correlated with proteoglycan loss, suggesting hyperglycemic stress after Rap treatment was related to worsened OA.ConclusionsThis is the first study to show that Rap induced increase in plasma glucose was associated with greater OA severity. Further, articular cartilage mTORC1 inhibition and bodyweight reduction by dietary Rap and Rap+Met did not appear to protect against primary OA during the prevailing hyperglycemia.

Betaine Attenuates Osteoarthritis by Inhibiting Osteoclastogenesis and Angiogenesis in Subchondral Bone.

Osteoarthritis (OA) is the most common type of arthritis with no effective therapy. Subchondral bone and overlying articular cartilage are closely associated and function as “osteo-chondral unit” in the joint. Abnormal mechanical load leads to activated osteoclast activity and increased bone resorption in the subchondral bone, which is implicated in the onset of OA pathogenesis. Thus, inhibiting subchondral bone osteoclast activation could prevent OA onset. Betaine, isolated from the Lycii Radicis Cortex (LRC), has been demonstrated to exert anti-inflammatory, antifibrotic and antiangiogenic properties. Here, we evaluated the effects of betaine on anterior cruciate ligament transection (ACLT)-induced OA mice. We observed that betaine decreased the number of matrix metalloproteinase 13 (MMP-13)-positive and collagen X (Col X)-positive cells, prevented articular cartilage proteoglycan loss and lowered the OARSI score. Betaine decreased the thickness of calcified cartilage and increased the expression level of lubricin. Moreover, betaine normalized uncoupled subchondral bone remodeling as defined by lowered trabecular pattern factor (Tb.pf) and increased subchondral bone plate thickness (SBP). Additionally, aberrant angiogenesis in subchondral bone was blunted by betaine treatment. Mechanistically, we demonstrated that betaine suppressed osteoclastogenesis in vitro by inhibiting reactive oxygen species (ROS) production and subsequent mitogen-activated protein kinase (MAPK) signaling. These data demonstrated that betaine attenuated OA progression by inhibiting hyperactivated osteoclastogenesis and maintaining microarchitecture in subchondral bone.

How Teichoic Acids Could Support a Periplasm in Gram-Positive Bacteria, and Let Cell Division Cheat Turgor Pressure.

The cytoplasm of bacteria is maintained at a higher osmolality than the growth medium, which generates a turgor pressure. The cell membrane (CM) cannot support a large turgor, so there are two possibilities for transferring the pressure to the peptidoglycan cell wall (PGW): (1) the CM could be pressed directly against the PGW, or (2) the CM could be separated from the PGW by a periplasmic space that is isoosmotic with the cytoplasm. There is strong evidence for gram-negative bacteria that a periplasm exists and is isoosmotic with the cytoplasm. No comparable studies have been done for gram-positive bacteria. Here I suggest that a periplasmic space is probably essential in order for the periplasmic proteins to function, including especially the PBPs that remodel the peptidoglycan wall. I then present a semi-quantitative analysis of how teichoic acids could support a periplasm that is isoosmotic with the cytoplasm. The fixed anionic charge density of teichoic acids in the periplasm is ∼0.5 M, which would bring in ∼0.5 M Na+ neutralizing ions. This approximately balances the excess osmolality of the cytoplasm that would produce a turgor pressure of 19 atm. The 0.5 M fixed charge density is similar to that of proteoglycans in articular cartilage, suggesting a comparability ability to support pressure. An isoosmotic periplasm would be especially important for cell division, since it would allow CM constriction and PGW synthesis to avoid turgor pressure.

Analysis of the effect of cationic hyaluronic acid on articular cartilage

Purpose: Osteoarthritis (OA) is a degenerative disease of joint components such as articular cartilage, synovium, and subchondral bone. Although progress has been made in identifying therapeutic targets as the pathogenesis of the disease progresses, it is difficult to achieve sustained drug action on articular cartilage because of the constant circulation of joint fluid by capillaries and lymphatic vessels in the synovium. Aglycan, a major proteoglycan in articular cartilage, is negatively charged.

Loading during midstance of gait is associated with tibiofemoral articular cartilage composition following anterior cruciate ligament reconstruction

Loading during midstance of gait is associated with tibiofemoral articular cartilage composition following anterior cruciate ligament reconstruction

Characterization of connective tissues using near-infrared spectroscopy and imaging.

Near-infrared (NIR) spectroscopy is a powerful analytical method for rapid, non-destructive and label-free assessment of biological materials. Compared to mid-infrared spectroscopy, NIR spectroscopy excels in penetration depth, allowing intact biological tissue assessment, albeit at the cost of reduced molecular specificity. Furthermore, it is relatively safe compared to Raman spectroscopy, with no risk of laser-induced photothermal damage. A typical NIR spectroscopy workflow for biological tissue characterization involves sample preparation, spectral acquisition, pre-processing and analysis. The resulting spectrum embeds intrinsic information on the tissue's biomolecular, structural and functional properties. Here we demonstrate the analytical power of NIR spectroscopy for exploratory and diagnostic applications by providing instructions for acquiring NIR spectra, maps and images in biological tissues. By adapting and extending this protocol from the demonstrated application in connective tissues to other biological tissues, we expect that a typical NIR spectroscopic study can be performed by a non-specialist user to characterize biological tissues in basic research or clinical settings. We also describe how to use this protocol for exploratory study on connective tissues, including differentiating among ligament types, non-destructively monitoring changes in matrix formation during engineered cartilage development, mapping articular cartilage proteoglycan content across bovine patella and spectral imaging across the depth-wise zones of articular cartilage and subchondral bone. Depending on acquisition mode and experiment objectives, a typical exploratory study can be completed within 6 h, including sample preparation and data analysis.

The Effect of Low Dietary Vitamin K Intake on the Development of Osteoarthritis in Aging Mice

Abstract Objectives Epidemiological evidence suggests that low vitamin K status is associated with osteoarthritis (OA) development and progression. However, it is not clear if low vitamin K intake is causally linked to OA. To address this gap, we manipulated vitamin K intake in aging mice to test its effect on OA development. Methods Eleven-month old male C57BL/6J mice were randomly assigned to a low phylloquinone diet containing 120 mcg phylloquinone/kg diet (n = 32) or a control diet containing 1.5 mg phylloquinone/kg diet (n = 30) for 6 months. Knee OA was evaluated histologically using Safranin O and H&amp;E staining. Adjacent sections were immunostained using antibodies directed against matrix gla protein (MGP) and gla rich protein (GRP), two vitamin K-dependent proteins present in cartilage that are implicated in OA. Post-mortem phylloquinone concentrations in liver, kidney, intestine, and brain were measured using HPLC. Results While body weight gain was comparable between the two groups (repeated measures ANOVA, group P = 0.63, group*time P = 0.77, time P &amp;lt; 0.01), mortality was increased in the low phylloquinone diet group compared to the control group (eleven versus three mice) within the first 100 days of the experiment (log-rank test P = 0.02). The phylloquinone tissue concentrations were lower in the mice fed the low vitamin K diet compared to those fed the control diet (Wilcoxon test, all P &amp;lt; 0.01). Mice fed the low phylloquinone diet had higher Safranin-O scores (indicative of articular cartilage proteoglycan loss) compared to mice fed the control diet [median (interquartile range) = 20 (11) and 14 (14), respectively; Wilcoxon two sample test P = 0.01]. The articular cartilage structure scores did not differ between the two groups [median (interquartile range) = 11 (11) and 9 (9), respectively; Wilcoxon test P = 0.19]. While MGP and GRP were expressed in articular and meniscal cartilage, expression did not differ significantly between the two groups (Wilcoxon P ≥ 0.24). Conclusions Our findings suggest low vitamin K status can promote articular cartilage proteoglycan loss in older male mice. Future studies are needed to confirm our findings and obtain a better understanding of the molecular mechanisms underlying vitamin K's role in OA. Funding Sources The National Institute of Arthritis, Musculoskeletal and Skin Disease and the US Department of Agriculture.

Blue Mussel (Mytilus edulis) Water Extract Ameliorates Inflammatory Responses and Oxidative Stress on Osteoarthritis in Obese Rats.

PurposeTo investigate the effects of Mytilus edulis water extract (MWE) on an anterior cruciate ligament transection and a partial medial meniscectomy surgery to induced osteoarthritis (OA) with the high-fat diet (HFD)-induced obese rats.MethodsThe male Sprague-Dawley rats were fed with HFD for 4 weeks before surgery. The OA rats were orally administered with MWE (108.5, 217.0, and 542.5 mg/kg) for 6 weeks.ResultsThe administration of MWE affected weight loss, triglycerides content, and total cholesterol level. MWE also enhanced the activity of superoxide dismutase and decreased lipid peroxidation degree. Moreover, MWE reduced proinflammatory cytokines level, alleviated inflammation and swelling of the osteoarthritic knee, and reduced loss of proteoglycan in articular cartilage tissue.ConclusionMWE suppressed proinflammatory mediators and attenuated the cartilage degradation and pain in osteoarthritis rats under obesity condition. Therefore, MWE has the potential to act as an alternative for osteoarthritis treatment.