Human Knee Osteoarthritis Research Articles

Influence of different sized nanoparticles combined with ultrasound on the optical properties of in vitro knee joint and knee osteoarthritis cartilage tissue was studied by OCT and diffuse reflectance spectroscopy

The penetration and accumulation of zinc oxide nanoparticles (ZnO NPs) with different sizes in human normal knee joint (NKJ) tissue and knee osteoarthritis (OA) tissue were studied by continuous optical coherence tomography and diffuse reflectance (DR) spectroscopy in this paper, and the effects of ZnO NPs of two sizes (30 nm and 90 nm) and ultrasound (US) on the optical properties of human NKJ and OA tissue were evaluated. The results show that the average attenuation coefficients of NKJ tissue decrease by 14.90%, 26.91%, 33.52% and 37.01%, and the DR spectra increases by 8.444%, 12.901%, 18.219% and 26.125%, respectively, after being treated with 90 nm ZnO NPs, 90 nm ZnO NPs/US, 30 nm ZnO NPs and 30 nm ZnO NPs/US. The average attenuation coefficients of OA tissue are reduced by 32.14%, 49.51%, 57.85% and 72.30%, and the DR spectra increase by 17.426%, 23.116%, 25.218% and 29.326%, respectively, after being treated with 90 nm ZnO NPs, 90 nm ZnO NPs/US, 30 nm ZnO NPs and 30 nm ZnO NPs/US. It is concluded that the optical properties of NKJ and OA tissues are greatly influenced by ZnO NPs and US. Nanoparticles have a greater impact on OA tissue than on NKJ tissue.

A New Method to Develop the Primate Model of Knee Osteoarthritis With Focal Cartilage Defect.

Objective: Osteoarthritis (OA) is a common degenerative joint disease, and animal models have proven pivotal in investigating this disease. This study aimed to develop a primate model of OA that may be more relevant to research studies on OA in humans. Method: Twelve female rhesus macaques were randomly divided into three groups. Four animals were untreated (Control group); four were subjected to the modified Hulth method, involving cutting of the anterior and posterior cruciate ligaments, and transecting the meniscus (Hulth group); and four were subjected to the modified Hulth method combined with cartilage defect (MHCD group). Each primate was subjected to motor ability tests, and underwent arthroscopic, radiographic, morphological, and pathological observation of the knee joints at various times for up to 180 days. Results: Motor ability on Day 180 was significantly lower in the MHCD group than in the Control (p＜0.01) and Hulth (p＜0.05) groups. Radiographic and morphological examination showed that the severity of knee joint deformity and articular cartilage injury were greater in the MHCD group than in the other groups. Pathological examination showed that cartilage thickness was significantly lower in the MHCD group than in the other groups at the same time points. The Mankin score on Day 180 was markedly higher in the MHCD group than in the Hulth (p＜0.05) and Control (p＜0.001) groups. Conclusion: The MHCD model of OA closely resembles the pathophysiological processes of spontaneous knee OA in humans. The time required to develop knee OA is shorter using the MHCD model than using the Hulth method.

Prospective Isolation and Characterization of Chondroprogenitors from Human Chondrocytes Based on CD166/CD34/CD146 Surface Markers.

Chondrocytes, isolated from articular cartilage, are routinely utilized in cell-based therapeutics for the treatment of cartilage pathologies. However, restoration of the biological tissue faces hindrance due to the formation of primarily fibrocartilaginous repair tissue. Chondroprogenitors have been reported to display superiority in terms of their chondrogenic potential and lesser proclivity for hypertrophy. In line with our recent results, comparing chondroprogenitors and chondrocytes, we undertook isolation of progenitors from the general pool of chondrocytes, based on surface marker expression, namely, CD166, CD34, and CD146, to eliminate off-target differentiation and generate cells of stronger chondrogenic potential. This study aimed to compare chondrocytes, chondroprogenitors, CD34-CD166+CD146+ sorted chondrocytes, and CD34-CD166+CD146- sorted chondrocytes. Chondrocytes obtained from 3 human osteoarthritic knee joints were subjected to sorting, to isolate CD166+ and CD34- subsets, and then were further sorted to obtain CD146+ and CD146- cells. Chondrocytes and fibronectin adhesion-derived chondroprogenitors served as controls. Assessment parameters included reverse transcriptase polymerase chain reaction for markers of chondrogenesis and hypertrophy, trilineage differentiation, and total GAG/DNA content. Based on gene expression analysis, CD34-CD166+CD146+ sorted chondrocytes and chondroprogenitors displayed comparability and significantly higher chondrogenesis with a lower tendency for hypertrophy when compared to chondrocytes and CD34-CD166+CD146- sorted chondrocytes. The findings were also reiterated in multilineage potential differentiation with the 146+ subset and chondroprogenitors displaying lower calcification and chondroprogenitors displaying higher total GAG/DNA content compared to chondrocytes and 146- cells. This unique progenitor-like population based on CD34-CD166+CD146+ sorting from chondrocytes exhibits efficient potential for cartilage repair and merits further evaluation for its therapeutic application.

Auricular acupressure for treating early stage of knee osteoarthritis: a randomized, sham-controlled prospective study.

We examined whether auricular acupressure (AA) at four specifically preselected AA points can alleviate knee pain and decrease non-steroidal anti-inflammatory drugs (NSAIDs) consumption and its adverse effects for osteoarthritis patients. Sixty-two patients (more than 40 years) with knee osteoarthritis of Kellgren-Lawrence grades of I or II upon radiographic classification were enrolled in this randomized, sham-controlled prospective study, and divided into two groups (AA group and control group). The AA group received true AA by embedding vaccaria seeds at four specific AA points (knee joint, shenmen, subcortex and sympathesis) ipsilateral to the knee osteoarthritis site, while the control group received four nonacupuncture points on the auricular helix. Visual analog scale (VAS), the Western Ontario and McMaster Universities Arthritis Index (WOMAC) score, the number of patients who needed celecoxib pills and adverse effects were recorded. VAS and WOMAC scores in the AA group were significantly lower than that in the control group (P < 0.05) at Days 3 and 7 postsugery. The VAS and WOMAC score were significantly decreased after the treatment in the AA group compared with that before the treatment (P < 0.05). The use of celebrex is significantly lower in the AA group than in the control group (P < 0.05), no major side effects were observed during the auricular acupressure treatment. Auricular acupressure plays a role in analgesic effect and can effectively decrease NSAIDs requirements without causing adverse events for the treatment of human knee osteoarthritis.

Deletion of Hyaluronan-Binding Protein Involved in Hyaluronan Depolymerization (HYBID) Results in Attenuation of Osteoarthritis in Mice

Hyaluronan (HA)-binding protein involved in HA depolymerization (HYBID) is involved in cartilage destruction via HA depolymerization in human knee osteoarthritis. However, the role of HYBID in the progression of osteoarthritis remain elusive. This study sought to examine whether genetic depletion of Hybid could suppress surgically induced osteoarthritis of mouse knee joints. In osteoarthritis induced by medial collateral ligament transection with meniscus removal, articular cartilage destruction and osteophyte formation at the medial femoral-tibial joint were significantly inhibited in Hybid-deficient (Hybid-/-) mice compared with wild-type mice. Hybid was highly produced by synovial cells and articular chondrocytes in the osteoarthritis joints of wild-type mice. IL-1β, IL-6, and tumor necrosis factor-α were up-regulated in the osteoarthritis joint tissues of both wild-type and Hybid-/- mice. Vascular density at the synovial and periosteal junction was significantly reduced in Hybid-/- mice compared with wild-type mice. High-molecular-weight HA accumulated in osteoarthritis joint tissues of Hybid-/- mice. Injections of high-molecular-weight HA to knee joints attenuated the cartilage destruction and osteophyte formation in wild-type mouse osteoarthritis group. Inhibition of cartilage destruction and osteophyte formation in Hybid-/- mice was also observed in destabilization of the medial meniscus model. These data are the first to demonstrate that cartilage destruction and osteophyte formation are suppressed in Hybid-/- mice and suggest that Hybid-mediated HA depolymerization is implicated for the progression of mechanically-induced knee osteoarthritis.

Tissue Collection and RNA Extraction from the Human Osteoarthritic Knee Joint.

Osteoarthritis (OA) is a chronic and degenerative joint disease most often affecting the knee. As there is currently no cure, total knee arthroplasty (TKA) is a common surgical intervention. Experiments using primary human OA tissues obtained from TKA provide the capability to investigate disease mechanisms ex vivo. While OA was previously thought to impact mainly the cartilage, it is now known to impact multiple tissues in the joint. This protocol describes patient selection, sample processing, tissue homogenization, RNA extraction, and quality control (based on RNA purity, integrity, and yield) from each of seven unique tissues to support disease mechanism investigation in the knee joint. With informed consent, samples were obtained from patients undergoing TKA for OA. Tissues were dissected, washed, and stored within 4 h of surgery by flash freezing for RNA or formalin fixation for histology. Collected tissues included articular cartilage, subchondral bone, meniscus, infrapatellar fat pad, anterior cruciate ligament, synovium, and vastus medialis oblique muscle. RNA extraction protocols were tested for each tissue type. The most significant modification involved the method of disintegration used for low-cell, high-matrix, hard tissues (considered as cartilage, bone, and meniscus) versus relatively high-cell, low-matrix, soft tissues (considered as fat pad, ligament, synovium, and muscle). It was found that pulverization was appropriate for hard tissues, and homogenization was appropriate for soft tissues. A proclivity for some subjects to yield higher RNA integrity number (RIN) values than other subjects consistently across multiple tissues was observed, suggesting that underlying factors such as disease severity may impact RNA quality. The ability to isolate high-quality RNA from primary human OA tissues provides a physiologically relevant model for sophisticated gene expression experiments, including sequencing, that can lead to clinical insights that are more readily translated to patients.

Tissue Collection and RNA Extraction from the Human Osteoarthritic Knee Joint

Tissue Collection and RNA Extraction from the Human Osteoarthritic Knee Joint

Allogenic Human Umbilical Cord Derived Mesenchymal Stem Cells for Managing Knee Osteoarthritis in Human – A Clinical Trial

Introduction: Human Mesenchymal Stem Cell has been scientifically accepted as a method of managing Osteoarthritis in the Human knee. They can be derived from Autologous Bone Marrow, Adipose Tissue, and less commonly Synovial Cells. However, Allogenic Human Umbilical Cord derived Mesenchymal Stem Cells has recently generated interest because harvesting it is noninvasive, availability easy, the cells relatively younger, have insignificant antigenic markers. A Clinical Trial of Allogeneic Intraarticular Human Umbilical Cord derived Mesenchymal Stem Cells was conducted to assess their efficacy in Osteo Arthritis Human Knees. Material and Method: The clinical trials were conducted from my clinic at 72 Tagore Town, Allahabad, UP, India from December 2018 to the third week of March 2021. The period of study was between December 2018 to April 2021. FIRST COVID Lockdown in this city was from 22nd of March 2020 to September 2020. The second Lockdown was from April 2021 to May 2021. Nine human subjects were selected initially for this clinical trial, but three were lost to follow-up. So 6 human subjects with bilateral knee Osteoarthritis (12 knees with OA) were studied in this clinical trial. The severity of the Knee Osteoarthritis was grade 2 to 3 of KL Score. After patient selection, Pre-Intra-Articular Injection, a Clinical Examination -General and local Knee Examination was done. Pre-determined functional outcome assessments using KOOS (Knee Injury and Osteoarthritis Scale) Outcome score, validated in Hindi, VAS (Visual Analogue Scale) Score, Kellgren Lawrence Score (KL Score), and Basal Metabolic Index recorded. After an Informed consent, each Knee was injected One Intraarticular Injection of Allogeneic Human umbilical Cord derived Mesenchymal Stem Cell (50x10^6). Cells were provided courtesy MEDITEKFUTURO, for this Clinical Trial. Six subjects with 12 knees were in this clinical trial. The follow-up after the Intra Articular Injection was at 15 ± 3 months and 24 ± 4 months. The first follow-up at 15 ± 3 months was during the first Covid Lockdown, done digitally by remote means, (The First Covid Lockdown in This District of Allahabad, State of Uttar Pradesh, India was from 22nd March 2020 to September 2020). The Lockdown was opened from October 2020 to April 2021. During this window, the second follow up 24 ± 4 months, was done clinically. (The second COVID lockdown was restarted from the end of April to 31st 2021 to the end of May 2021, in this City). The follow up post-injection results at 15 ± 3months and at 24 ± 4 months, recorded importantly for adverse reaction as per WHO guidelines (using CTCAE version 3 of NCI Common Terminology Criteria for Adverse Events, functional parameters did preoperatively were serially recorded at the two follow up period mentioned, and analyzed. The correlation with age and BMI was also analyzed. Results: • Allogenic Human Umbilical Cord derived Mesenchymal Stem Cells used as Intra articular Knee injections were found effective for managing Human Knee Osteoarthritis. • No local or generalized complications were observed by its use. • Knee function as assessed by KOOS Scale and VAS scale improved. • The Improvement continued till the end of the study. • The Clinical Outcomes continued with increasing age and BMI. Till the period of this Clinical trial. • The clinical trial during 15 ± 3months was done during the COVID lockdown using digital means of the functional KOOS and Vas scoring, which was done out of compulsion. • A larger multicenter trial for a longer time frame, of this Clinical Trial would be more statistically significant.

Effects of intra-articular corticosteroid versus platelet- rich plasma on induced knee osteoarthritis in adult albino rats. Histological and anatomical study

ABSTRACTBackground: Osteoarthritis (OA) is a common degenerative joint disease. Intra-articular injection of microcrystalline corticosteroid and platelet- rich plasma (PRP) are used for pain relief of knee OA.Aim of the Study: the goal of this study was to assess the possible therapeutic effects of corticosteroid compared to PRP in a rat model of induced OA.Material and Methods: Intra-articular injection of monosodium iodoacetate (MIA) was used for induction of OA in rats. Blood was collected from12 adult male rats for PRP preparation. 54 adult female albino rats were divided into control groups, OA model group and treated groups which received CS or PRP. All rats were euthanized after 28 days. Left knee joints were processed for histological examination by light microscope after staining by H& E, toluidine blue and masson’s trichrome stains. Right knee joints were grossly examined by stereomicroscope and scanning electron microscope (SEM). The obtained data were examined, further statistically analyzed and interpreted. Results: MIA caused gross anatomical and histological alterations in rat’s articular cartilage similar to human knee OA. Articular cartilage of corticosteroid and PRP treated knee joints showed thinning of the articular cartilage, fibrillation and presence of pannus- like tissue. These groups also showed significant increase in histopathological scores compared to the control group and OA model group in addition to gross macroscopic changes that were confirmed by SEM.Conclusion: This study showed that neither corticosteroid nor PRP could limit the structural changes in osteoarthritis and that different PRP preparation techniques have yielded varying results.

Biomechanical-Based Protocol for in vitro Study of Cartilage Response to Cyclic Loading: A Proof-of-Concept in Knee Osteoarthritis.

Osteoarthritis (OA) is an evolving disease and a major cause of pain and impaired mobility. A deeper understanding of cartilage metabolism in response to loading is critical to achieve greater insight into OA mechanisms. While physiological joint loading helps maintain cartilage integrity, reduced or excessive loading have catabolic effects. The main scope of this study is to present an original methodology potentially capable to elucidate the effect of cyclic joint loading on cartilage metabolism, to identify mechanisms involved in preventing or slowing down OA progression, and to provide preliminary data on its application. In the proposed protocol, the combination of biomechanical data and medical imaging are integrated with molecular information about chondrocyte mechanotransduction and tissue homeostasis. The protocol appears to be flexible and suitable to analyze human OA knee cartilage explants, with different degrees of degeneration, undergoing ex vivo realistic cyclic joint loading estimated via gait analysis in patients simulating mild activities of daily living. The modulation of molecules involved in cartilage homeostasis, mechanotransduction, inflammation, pain and wound healing can be analyzed in chondrocytes and culture supernatants. A thorough analysis performed with the proposed methodology, combining in vivo functional biomechanical evaluations with ex vivo molecular assessments is expected to provide new insights on the beneficial effects of physiological loading and contribute to the design and optimization of non-pharmacological treatments limiting OA progression.

Resistin induces chemokine and matrix metalloproteinase production via CAP1 receptor and activation of p38-MAPK and NF-κB signalling pathways in human chondrocytes.

Adipokine resistin is highly expressed in the serum and synovial uid (SF) of patients with knee osteoarthritis (KOA) but its pathogenic role in KOA remains unclear. We aimed to explore the mechanism of resistin/CAP1 in human KOA chondrocytes. We enrolled 103 patients with radiographic KOA and 86 healthy participants as controls. Resistin levels in serum and SF were determined by enzyme-linked immunosorbent assay (ELISA). CAP1 expression was measured in cartilage tissues using immunohistochemistry, quantitative real-time polymerase chain reaction (qRT-PCR), and western blot. Effects of resistin on chondrocytes and CAP1 were evaluated via qRT-PCR and co-immunoprecipitation. The roles of CAP1, p38-MAPK, and NF-κB signalling pathways in KOA development were evaluated using adenovirus-mediated CAP1 short hairpin RNA, qRT-PCR, western blot, and ELISA. Resistin expression in serum and SF was elevated in severe radiographic KOA. CAP1 levels were higher in KOA cartilage and were positively correlated with resistin expression. Resistin promoted CCL3, CCL4, MMP13, and ADAMTS-4 expression through the CAP1 receptor. Resistin also directly bound to CAP1, as confirmed by co-immunoprecipitation. CAP1 knockdown in chondrocytes attenuated resistin-induced expression of CCL3, CCL4, MMP13, and ADAMTS-4 and activated p38-MAPK and NF-κB signalling pathways. Resistin binds CAP1 and upregulates the expression of proinflammatory cytokines and matrix-degrading enzymes via p38-MAPK and NF-κB signalling in human chondrocytes.

Elevated levels of active transforming growth factor β1 in the subchondral bone relate spatially to impaired bone quality and cartilage loss in human knee osteoarthritis

Purpose: Both animal and human studies indicate that changes of subchondral bone play an important pathogenic role in the initiation development and progression of osteoarthritis (OA). Transforming Growth Factor β1 (TGFβ1) is abundant in bone where it has multiple essential roles in development, homeostasis and repair, maintaining both bone volume and bone quality. Further, it has been shown that over-activity of TGFβ1 in subchondral bone has a direct causal role in rodent knee OA, which can be blocked by TGFβ1 neutralization.

Elevated levels of active Transforming Growth Factor β1 in the subchondral bone relate spatially to cartilage loss in human knee osteoarthritis

Elevated levels of active Transforming Growth Factor β1 in the subchondral bone relate spatially to cartilage loss in human knee osteoarthritis

Agnuside Alleviates Synovitis and Fibrosis in Knee Osteoarthritis through the Inhibition of HIF-1α and NLRP3 Inflammasome.

Increasing evidence has shown that NLRP3 inflammasome activation participates in chronic aseptic inflammation and is related to tissue fibrosis. Our last study also revealed the vital role of NLRP3 inflammasome, highly associated with tissue hypoxia, in the onset and development of knee osteoarthritis (KOA). In this study, we tried to find a possible benign intervention for that pathological process. Agnuside (AGN), a nontoxic, natural small molecule isolated from the extract of Vitex negundo L. (Verbenaceae), has been demonstrated to have antioxidation, anti-inflammatory, analgesia, and many other properties as an iridoid glycoside, although its specific target is still unclear. Therefore, we established MIA-induced KOA model rats and investigated the effects of AGN oral gavage on oxygen-containing state, NLRP3 inflammasome, synovitis, and fibrosis in KOA. Pimonidazole staining and HIF-1α immunohistochemical assay both showed that AGN at the oral dose of 6.25 mg/kg can effectively relieve local hypoxia in synovial tissue. Besides, we observed a decrease of HIF-1α, caspase-1, ASC, and NLRP3 after AGN intervention, both in the mRNA and protein levels. In addition, rats treated with the AGN showed less inflammatory reaction and fibrosis, not only in the expression of NLRP3, inflammasome downstream factors IL-1β and IL-18, and fibrosis markers TGF-β, TIMP1, and VEGF but also in the observation of HE staining, anatomical characteristics, Sirius Red staining, and type I collagen immunohistochemistry. Subsequently, we established LPS-induced models of fibroblast-like synoviocytes (FLSs) mimicking the inflammatory environment of KOA and activating NLRP3 inflammasome. FLSs treated with AGN (3 μM) resulted in a downregulation of HIF-1α and the components required for NLRP3 inflammasome activation. Meanwhile, the content of proinflammatory factors IL-1β and IL-18 in FLS supernatant was also reduced by AGN. In addition, both mRNA and protein levels of the fibrotic markers were significantly decreased after AGN management. To conclude, this study demonstrates that AGN alleviates synovitis and fibrosis in experimental KOA through the inhibition of HIF-1α accumulation and NLRP3 inflammasome activation. Additionally, not only does it reveal some novel targets for anti-inflammatory and antioxidant effects of AGN but also announces its potential value in treating KOA in humans.

PROXIMAL FIBULAR OSTEOTOMY VERSUS MEDIAL OPENING WEDGE HIGH TIBIAL OSTEOTOMY TO TREAT MEDIAL COMPARTMENT KNEE OSTEOARTHRITIS: A RANDOMIZED CLINICAL TRIAL

Background: Osteoarthritis is the most common cause of disability in the older population. Disability is caused by pain and limitations in mobility. Total knee arthroplasty, which aims to relieve pain and improve joint function and mobility, is the main surgical alternative in this patient population.Aim of the work: The aim of this work is to compare the functional and radiological outcomes of proximal fibular osteotomy in medial compartment decompression, with medial opening wedge high tibial osteotomy.Patients and Methods: This prospective randomized clinical trial was done between March 2017 and May 2019 on 40 patients suffering from manifestation of medial compartment osteoarthritis of the knee joint. Patients were allocated into two groups: Control group; 20 patients representing the standard HTO technique and Case group; 20 patients representing the novel technique PFO.Results: In our study we compared the outcome of 40 patient complaining of medial knee OA according to VAS, KSS and radiological assessment of joint space, we found improvement in outcome of HTO than PFO. However, PFO may be a promising alternative in most developing countries because of their financial and healthcare delivery limitations. Furthermore, these patients can still undergo TKA in the future if it becomes necessary, PFO may be considered in patients with mild medial compartment osteoarthritis over HTO.Conclusion: Our preliminary data clearly demonstrate that PFO is a simple, fast and affordable surgery to relieve pain and improve joint function and the medial joint space in human knee osteoarthritis. However, in this study we only assessed the short term follow up, so further studies are needed to assess the long-term outcome.

Zinc finger protein-440 promotes cartilage degenerative mechanisms in human facet and knee osteoarthritis chondrocytes

To investigate the role of zinc finger protein 440 (ZNF440) in the pathophysiology of cartilage degeneration during facet joint (FJ) and knee osteoarthritis (OA). Expression of ZNF440 in FJ and knee cartilage was determined by immunohistochemistry, quantitative (q)PCR, and Western blotting (WB). Human chondrocytes isolated from FJ and knee OA cartilage were cultured and transduced with ZNF440 or control plasmid, or transfected with ZNF440 or control small interfering RNA (siRNA), with/without interleukin (IL)-1β. Gene and protein levels of catabolic, anabolic and apoptosis markers were determined by qPCR or WB, respectively. In silico analyses were performed to determine compounds with potential to inhibit expression of ZNF440. ZNF440 expression was increased in both FJ and knee OA cartilage compared to control cartilage. In vitro, overexpression of ZNF440 significantly increased expression of MMP13 and PARP p85, and decreased expression of COL2A1. Knockdown of ZNF440 with siRNA partially reversed the catabolic and cell death phenotype of human knee and FJ OA chondrocytes stimulated with IL-1β. In silico analysis followed by validation assays identified scriptaid as a compound with potential to downregulate the expression of ZNF440. Validation experiments showed that scriptaid reduced the expression of ZNF440 in OA chondrocytes and concomitantly reduced the expression of MMP13 and PARP p85 in human knee OA chondrocytes overexpressing ZNF440. The expression of ZNF440 is significantly increased in human FJ and knee OA cartilage and may regulate cartilage degenerative mechanisms. Furthermore, scriptaid reduces the expression of ZNF440 and inhibits its destructive effects in OA chondrocytes.

Mineral Crystal Thickness in Calcified Cartilage and Subchondral Bone in Healthy and Osteoarthritic Human Knees.

ABSTRACTOsteoarthritis (OA) is the most common joint disease, where articular cartilage degradation is often accompanied with sclerosis of the subchondral bone. However, the association between OA and tissue mineralization at the nanostructural level is currently not understood. In particular, it is technically challenging to study calcified cartilage, where relevant but poorly understood pathological processes such as tidemark multiplication and advancement occur. Here, we used state‐of‐the‐art microfocus small‐angle X‐ray scattering with a 5‐μm spatial resolution to determine the size and organization of the mineral crystals at the nanostructural level in human subchondral bone and calcified cartilage. Specimens with a wide spectrum of OA severities were acquired from both medial and lateral compartments of medial compartment knee OA patients (n = 15) and cadaver knees (n = 10). Opposing the common notion, we found that calcified cartilage has thicker and more mutually aligned mineral crystals than adjoining bone. In addition, we, for the first time, identified a well‐defined layer of calcified cartilage associated with pathological tidemark multiplication, containing 0.32 nm thicker crystals compared to the rest of calcified cartilage. Finally, we found 0.2 nm thicker mineral crystals in both tissues of the lateral compartment in OA compared with healthy knees, indicating a loading‐related disease process because the lateral compartment is typically less loaded in medial compartment knee OA. In summary, we report novel changes in mineral crystal thickness during OA. Our data suggest that unloading in the knee might be involved with the growth of mineral crystals, which is especially evident in the calcified cartilage. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

LncRNA GAS5 induces chondrocyte apoptosis by down-regulating miR-137.

Long non-coding RNA (lncRNA) participates in the pathogenesis of human knee osteoarthritis (KOA). Growth arrest specificity 5 (GAS5) is a member lncRNA, but its role in pathological regulation of KOA is still unknown. This study aims to explore the mechanism of GAS5 in KOA on chondrocyte apoptosis and other pathological processes. The serum and cartilage tissues were collected from 35 patients with KOA and 30 patients with traumatic amputation admitted to our hospital from April 2016 to April 2020. The expressions of GAS5 and miR-137 were detected and analyzed. Chondrocytes were extracted from cartilage tissues of KOA patients, and the genes were regulated by transfection. Then, the cells were detected, including apoptosis, apoptosis-related proteins (caspase-3, Bax/Bcl-2), and proliferation. The targeting relationship between GAS5 and miR-137 was verified. GAS5 was up-regulated in serum and cartilage tissues of KOA patients, and down-regulation of GAS5 could inhibit the apoptosis process of chondrocytes and promote proliferation. MiR-137 was down-regulated in samples of KOA patients and was negatively regulated by GAS5. GAS5 induced apoptosis of chondrocytes and inhibited its proliferation through targeted down-regulating miR-137. GAS5 is up-regulated in KOA serum, cartilage tissues and cells, and can induce chondrocyte apoptosis through down-regulating miR-137.

Analysis of spatial osteochondral heterogeneity in advanced knee osteoarthritis exposes influence of joint alignment.

Osteoarthritis (OA) is considerably affected by joint alignment. Here, we investigate the patterns of spatial osteochondral heterogeneity in patients with advanced varus knee OA together with clinical data. We report strong correlations of osteochondral parameters within individual topographical patterns, highlighting their fundamental and location-dependent interactions in OA. We further identify site-specific effects of varus malalignment on the lesser loaded compartment and, conversely, an unresponsive overloaded compartment. Last, we trace compensatory mechanisms to the overloaded subarticular spongiosa in patients with additional high body weight. We therefore propose to consider and to determine axial alignment in clinical trials when selecting the location to assess structural changes in OA. Together, these findings broaden the scientific basis of therapeutic load redistribution and weight loss in varus knee OA.

Irisin Mitigates Oxidative Stress, Chondrocyte Dysfunction and Osteoarthritis Development through Regulating Mitochondrial Integrity and Autophagy.

Compromised autophagy and mitochondrial dysfunction downregulate chondrocytic activity, accelerating the development of osteoarthritis (OA). Irisin, a cleaved form of fibronectin type III domain containing 5 (FNDC5), regulates bone turnover and muscle homeostasis. Little is known about the effect of Irisin on chondrocytes and the development of osteoarthritis. This study revealed that human osteoarthritic articular chondrocytes express decreased level of FNDC5 and autophagosome marker LC3-II but upregulated levels of oxidative DNA damage marker 8-hydroxydeoxyguanosine (8-OHdG) and apoptosis. Intra-articular administration of Irisin further alleviated symptoms of medial meniscus destabilization, like cartilage erosion and synovitis, while improved the gait profiles of the injured legs. Irisin treatment upregulated autophagy, 8-OHdG and apoptosis in chondrocytes of the injured cartilage. In vitro, Irisin improved IL-1β-mediated growth inhibition, loss of specific cartilage markers and glycosaminoglycan production by chondrocytes. Irisin also reversed Sirt3 and UCP-1 pathways, thereby improving mitochondrial membrane potential, ATP production, and catalase to attenuated IL-1β-mediated reactive oxygen radical production, mitochondrial fusion, mitophagy, and autophagosome formation. Taken together, FNDC5 loss in chondrocytes is correlated with human knee OA. Irisin repressed inflammation-mediated oxidative stress and extracellular matrix underproduction through retaining mitochondrial biogenesis, dynamics and autophagic program. Our analyses shed new light on the chondroprotective actions of this myokine, and highlight the remedial effects of Irisin on OA development.