Histochemistry as a unique approach for investigating normal and osteoarthritic cartilage

Multimodal 2D and 3D microscopic mapping of growth cartilage by computational imaging techniques - a short review including new research

Being able to image the microstructure of growth cartilage is important for understanding the onset and progression of diseases such as osteochondrosis and osteoarthritis, as well as for developing new treatments and implants. Studies of cartilage using conventional optical brightfield microscopy rely heavily on histological staining, where the added chemicals provide tissue-specific colours. Other microscopy contrast mechanisms include polarization, phase- and scattering contrast, enabling non-stained or 'label-free' imaging that significantly simplifies the sample preparation, thereby also reducing the risk of artefacts. Traditional high-performance microscopes tend to be both bulky and expensive.Computational imagingdenotes a range of techniques where computers with dedicated algorithms are used as an integral part of the image formation process. Computational imaging offers many advantages like 3D measurements, aberration correction and quantitative phase contrast, often combined with comparably cheap and compact hardware. X-ray microscopy is also progressing rapidly, in certain ways trailing the development of optical microscopy. In this study, we first briefly review the structures of growth cartilage and relevant microscopy characterization techniques, with an emphasis on Fourier ptychographic microscopy (FPM) and advanced x-ray microscopies. We next demonstrate with our own results computational imaging through FPM and compare the images with hematoxylin eosin and saffron (HES)-stained histology. Zernike phase contrast, and the nonlinear optical microscopy techniques of second harmonic generation (SHG) and two-photon excitation fluorescence (TPEF) are explored. Furthermore, X-ray attenuation-, phase- and diffraction-contrast computed tomography (CT) images of the very same sample are presented for comparisons. Future perspectives on the links to artificial intelligence, dynamic studies andin vivopossibilities conclude the article.

A Mechanically Resilient Soft Hydrogel Improves Drug Delivery for Treating Post-Traumatic Osteoarthritis in Physically Active Joints

Intra-articular delivery of disease-modifying osteoarthritis drugs (DMOADs) is likely to be most effective in early post-traumatic osteoarthritis (PTOA) when symptoms are minimal and patients are physically active. DMOAD delivery systems therefore must withstand repeated mechanical loading without affecting the drug release kinetics. Although soft materials are preferred for DMOAD delivery, mechanical loading can compromise their structural integrity and disrupt drug release. Here, we report a mechanically resilient soft hydrogel that rapidly self-heals under conditions resembling human running while maintaining sustained release of the cathepsin-K inhibitor L-006235 used as a proof-of-concept DMOAD. Notably, this hydrogel outperformed a previously reported hydrogel designed for intra-articular drug delivery, used as a control in our study, which neither recovered nor maintained drug release under mechanical loading. Upon injection into mouse knee joints, the hydrogel showed consistent release kinetics of the encapsulated agent in both treadmill-running and non-running mice. In a mouse model of aggressive PTOA exacerbated by treadmill running, L-006235 hydrogel markedly reduced cartilage degeneration. To our knowledge, this is the first hydrogel proven to withstand human running conditions and enable sustained DMOAD delivery in physically active joints, and the first study demonstrating reduced disease progression in a severe PTOA model under rigorous physical activity, highlighting the hydrogel's potential for PTOA treatment in active patients.

Ex vivo organotypic bone slice culture reveals preferential chondrogenesis after sustained growth plate injury

Postnatal bone growth primarily relies on chondrocyte proliferation and osteogenic differentiation within the growth plate (GP) via endochondral ossification. Despite its importance, the GP is vulnerable to injuries, affecting 15-30 % of bone fractures. These injuries may lead to growth discrepancies, influence bone length and shape, and negatively affecting the patient's quality of life. This study aimed to investigate the molecular and cellular physiological and pathophysiological regeneration following sustained growth plate injury (GPI) in an ex vivo rat femur organotypic culture (OTC) model. Specifically, focusing on postnatal endochondral ossification process. 300 μm thick ex vivo bone cultures with a 2 mm long horizontal GPI was utilized. After 15 days of cultivation, gene expression analysis, histological and immunohistochemistry staining's were conducted to analyze key markers of endochondral ossification. In our OTCs we observed a significant increase in Sox9 expression due to GPI at day 15. The Ihh-PTHrP feedback loop was affected, favoring chondrocyte proliferation and maturation. Ihh levels increased significantly on day 7 and day 15, while PTHrP was downregulated on day 7. GPI had no impact on osteoclast number and activity, but gene expression analysis indicated OTCs' efforts to inhibit osteoclast differentiation and activation, thereby reducing bone resorption. In conclusion, our study provides novel insights into the molecular and cellular mechanisms underlying postnatal bone growth and regeneration following growth plate injury (GPI). We demonstrate that chondrocyte proliferation and differentiation play pivotal roles in the regeneration process, with the Ihh-PTHrP feedback loop modulating these processes. Importantly, our ex vivo rat femur organotypic culture model allows for the detailed investigation of these processes, providing a valuable tool for future research in the field of skeletal biology and regenerative medicine.

A guide to preclinical evaluation of hydrogel-based devices for treatment of cartilage lesions

The drive to develop cartilage implants for the treatment of major defects in the musculoskeletal system has resulted in a major research thrust towards developing biomaterial devices for cartilage repair. Investigational devices for the restoration of articular cartilage are considered as significant risk materials by regulatory bodies and therefore proof of efficacy and safety prior to clinical testing represents a critical phase of the multidisciplinary effort to bridge the gap between bench and bedside. To date, review articles have thoroughly covered different scientific facets of cartilage engineering paradigm, but surprisingly, little attention has been given to the preclinical considerations revolving around the validation of a biomaterial implant. Considering hydrogel-based cartilage products as an example, the present review endeavors to provide a summary of the critical prerequisites that such devices should meet for cartilage repair, for successful implantation and subsequent preclinical validation prior to clinical trials. Considerations pertaining to the choice of appropriate animal model, characterization techniques for the quantitative and qualitative outcome measures, as well as concerns with respect to GLP practices are also extensively discussed. This article is not meant to provide a systematic review, but rather to introduce a device validation-based roadmap to the academic investigator, in anticipation of future healthcare commercialization. STATEMENT OF SIGNIFICANCE: There are significant challenges around translation of in vitro cartilage repair strategies to approved therapies. New biomaterial-based devices must undergo exhaustive investigations to ensure their safety and efficacy prior to clinical trials. These considerations are required to be applied from early developmental stages. Although there are numerous research works on cartilage devices and their in vivo evaluations, little attention has been given into the preclinical pathway and the corresponding approval processes. With a focus on hydrogel devices to concretely illustrate the preclinical path, this review paper intends to highlight the various considerations regarding the preclinical validation of hydrogel devices for cartilage repair, from regulatory considerations, to implantation strategies, device performance aspects and characterizations.

Antioxidant Efficacy of Esculetin against Tert-Butyl Hydroperoxide-Induced Oxidative Stress in HEK293 Cells

Esculetin is an antioxidant and anti-inflammatory compound derived from coumarin. Oxidative stress can cause overproduction of reactive oxygen species (ROS), which can lead to the development of chronic kidney failure. In this study, human embryonic kidney 293 (HEK293) cells were treated with tert-butyl hydroperoxide (t-BHP) to determine the antioxidant effects of esculetin. HEK293 cells were treated with t-BHP to validate changes in cell viability, ROS production, and apoptosis, and then treated with esculetin to evaluate the changes. Changes in mRNA and protein levels were analyzed using a proteome kit, PCR, and Western blotting. Esculetin improved HEK293 cell viability and reduced apoptosis caused by t-BHP-induced oxidative stress. At the mRNA and protein levels, esculetin decreased pro-apoptotic factor expression as well as increased anti-apoptotic factor expression. The antioxidant efficacy of esculetin was validated when it inhibited the apoptosis caused by t-BHP-induced oxidative stress in HEK293 cells.

A narrative review of mesenchymal stem cells effect on osteoarthritis

Objective

To describe and discuss the purposed mechanism of mesenchymal stem cells (MSCs) and their effect as a potential therapeutic in osteoarthritis (OA).

Background

OA is a chronic, degenerative joint disease affecting millions worldwide. Traditional management, including physical therapy, anti-inflammatories, intra-articular injections, and surgical procedures are directed towards symptom control rather than disease modification. In light of a better understanding that low-grade inflammation disrupts articular cartilage homeostasis in OA, application of MSCs as a form of regenerative medicine has emerged with the goal to provide symptomatic relief as well as reverse the articular cartilage damage seen in OA.

Methods

PubMed was searched using terms 'osteoarthritis', 'mesenchymal stem cell', 'regenerative medicine', 'chondrocyte', and 'articular cartilage' available from 2006 through May 2021.

Conclusions

The use of MSC therapy for articular cartilage regeneration through direct tissue growth, differentiation, and inflammation modulations for the treatment of OA is promising. MSCs migrate to injured sites, inhibit pro-inflammatory pathways, and promote tissue repair by releasing paracrine signals and differentiating into specialized chondrocytes. Multiple clinical trials have displayed a significant improvement in both pain and joint function, inflammatory cell reduction within a joint, and articular cartilage growth as well as patient safety. However, high quality evidence supporting the beneficial role of MSCs is lacking due to the limited number of studies, small populations tested, and the use of various derivatives. Although limited, current evidence suggests MSCs are a potential therapeutic in OA and provides a great foundation for further research.

Inhibition of HMGB1 suppresses inflammation and catabolism in temporomandibular joint osteoarthritis <em>via</em> NF-κB signaling pathway

HMGB1 is a highly conserved nuclear protein that is rapidly released into the extracellular environment during infection or tissue damage. In osteoarthritis, HMGB1 acts as a pro-inflammatory cytokine inducing a positive feedback loop for synovial inflammation and cartilage degradation. The aim of this study was to explore the role of HMGB1 in inflammation and catabolism of temporomandibular joint osteoarthritis (TMJOA) and whether inhibition of HMGB1 affects TMJOA. Human synovial fibroblasts were incubated with HMGB1, the expression of pro-inflammatory cytokines and catabolic mediators were measured by Western blot and ELISA. NF-κB signaling pathway involvement was studied by the NF-κB inhibitor and detected by Western blotting and immunofluorescence staining. TMJOA was induced by an injection of complete Freund’s adjuvant (CFA) into anterosuperior compartment of rat’s joint. An anti-HMGB1 antibody was used to assess the effect to HMGB1 in the synovium and cartilage of the CFA-induced TMJOA rats by hematoxylin and eosin, Safranin O, Masson trichrome staining, immunohistochemistry and immunofluorescence. HMGB1 markedly increased the production of MMP13, ADAMTS5, IL-1β and IL-6 through activating NF-κB signaling pathway in human synovial fibroblasts. In vivo, application of the HMGB1 neutralizing antibody effectively ameliorated the detrimental extent of TMJOA. Furthermore, the HMGB1 neutralizing antibody reduced the expression of NF-κB, pro-inflammatory cytokines and catabolic mediators in the synovium and cartilage of CFA-induced TMJOA rats. HMGB1 inhibition alleviates TMJOA by reducing synovial inflammation and cartilage catabolism possibly through suppressing the NF-κB signaling pathway and may become a therapeutic method against TMJOA.

Chondroprotective Effects of 4,5-Dicaffeoylquinic Acid in Osteoarthritis through NF-κB Signaling Inhibition

Osteoarthritis (OA) is characterized by cartilage degradation, inflammation, and pain. The dicaffeoylquinic acid (diCQA) isomer, 4,5-diCQA, exhibits antioxidant activity and various other health-promoting benefits, but its chondroprotective effects have yet to be elucidated. In this study, we aimed to investigate the chondroprotective effects of 4,5-diCQA on OA both in vitro and in vivo. Primary rat chondrocytes were pre-treated with 4,5-diCQA for 1 h before stimulation with interleukin (IL)-1β (5 ng/mL). The accumulation of nitrite, PGE₂, and aggrecan was observed using the Griess reagent and ELISA. The protein levels of iNOS, COX-2, MMP-3, MMP-13, ADMATS-4, MAPKs, and the NF-κB p65 subunit were measured by Western blotting. In vivo, the effects of 4,5-diCQA were evaluated for 2 weeks in a destabilization of the medial meniscus (DMM)-surgery-induced OA rat model. 4,5-diCQA significantly inhibited IL-1β-induced expression of nitrite, iNOS, PGE₂, COX-2, MMP-3, MMP-13, and ADAMTS-4. 4,5-diCQA also decreased the IL-1β-induced degradation of aggrecan. It also suppressed the IL-1β-induced phosphorylation of MAPKs and translocation of the NF-κB p65 subunit to the nucleus. These findings indicate that 4,5-diCQA inhibits DMM-surgery-induced cartilage destruction and proteoglycan loss in vivo. 4,5-diCQA may be a potential therapeutic agent for the alleviation of OA progression. In this study, diclofenac was set to be administered once every two days, but it showed an effect on OA. These results may be used as basic data to suggest a new dosing method for diclofenac.

Mineral deposition intervention through reduction of phosphorus intake suppresses osteoarthritic lesions in temporomandibular joint

OBJECTIVE

To explore the suppressing impact of low phosphorus intake on osteoarthritic temporomandibular joint and the possible mechanisms of nuclear acid injury in the insulted chondrocytes.

DESIGN

Chondrocytes were loaded with fluid flow shear stress (FFSS) with or without low phosphorus medium. Seventy-two mice (sampled at 3-, 7- and 11-wk, n = 6) and forty-eight rats (sampled at 12-wks for different testing purpose, n = 6) were applied with unilateral anterior crossbite (UAC) with or without low phosphorus diet. In the FFSS model, the Ca and P content, molecules related to nucleic acid degradation and the mineral-producing responses in chondrocytes were detected. The effect of culture dish stiffness on chondrocytes osteogenic differentiation was measured. In the UAC model, the content of Ca and P in serum were tested. The condylar cartilage ossification and stiffness were detected using micro-CT, scanning electron microscope and atomic force microscope.

RESULTS

FFSS induced nucleic acid degradation, Pi accumulation and mineral-producing responses in the cultured chondrocytes, all were alleviated by low P medium. Stiffer dish bottoms promoted the osteogenic differentiation of the cultured chondrocytes. UAC stimulated cartilage degeneration and chondrocytes nucleic acid damage, increased PARP 1 and serum P content, and enhanced ossification and stiffening of the cartilage, all were suppressed by low phosphorus diet (all, P < 0.05).

CONCLUSION

Nucleic acid damage takes a role in phosphorus production in osteoarthritic cartilage, contributing to the enhanced mineralization and stiffness of the cartilage that in turn promotes cartilage degradation, which can be alleviated by low phosphorus intake.

The relationship between abnormal Core binding factor-β expression in human cartilage and osteoarthritis

Background

This study aimed to investigate the effect of abnormal Core binding factor-β expression on proliferation, differentiation and apoptosis of chondrocytes, and elucidate the relationship between Core binding factor-β and osteoarthritis-related markers and degenerative joint disease.

Methods

Cartilage tissues, from healthy subjects and patients with osteoarthritis, were collected for histology and expression of Core binding factor-β, MMP-13, IL-1β, COMP, and YKL-40. Human articular chondrocytes were cultured in vitro, and a viral vector was constructed to regulate cellular Core binding factor-β expression. Cellular proliferation and apoptosis were observed, and osteoarthritis-related inflammatory factor expression and cartilage metabolite synthesis assayed.

Results

Human osteoarthritis lesions had disordered cartilage structure and cellular arrangement, and increased emptying of cartilage lacunae. Normal cell counts were significantly reduced, cartilage extracellular matrix was obviously damaged, and type II collagen expression was significantly decreased. Core binding factor-β was highly expressed in the osteoarthritis cartilage (p < 0.001), and MMP-13, IL-1β, COMP and YKL-40 expression were greater than found in normal cartilage (p < 0.001). Cellular proliferation in the Core binding factor-β high-expression group was reduced and the total apoptosis rate was increased (p < 0.05), while the opposite was found in the Core binding factor-β inhibition group (p < 0.01). Compared with normal chondrocytes, high Core binding factor-β expression (Osteoarthritis and CBFB/pCDH groups) was associated with significantly increased MMP13, IL-1β, COMP and YKL-40 protein expression (p < 0.01), while Core binding factor-β inhibition (CBFB/pLKO.1 group) was associated with significantly decreased COMP, MMP13, IL-1β and YKL-40 expression in osteoarthritis cells (p < 0.001).

Conclusions

Abnormal Core binding factor-β expression might play an upstream regulatory role in mediating abnormal chondrocyte apoptosis and the inflammatory response. On inhibiting Core binding factor-β expression, a delay in cartilage degeneration was expected.

Trial registration

The study was registered for clinical trials in ChiCTR: ChiCTR1800017066 (Reg. Date-2018/7/10).

Innovative Tissue-Engineered Strategies for Osteochondral Defect Repair and Regeneration: Current Progress and Challenges

Clinical treatments for the repair of osteochondral defects (OCD) are merely palliative, not completely curative, and thus enormously unfulfilled challenges. With the in-depth studies of biology, medicine, materials, and engineering technology, the conception of OCD repair and regeneration should be renewed. During the past decades, many innovative tissue-engineered approaches for repairing and regenerating damaged osteochondral units have been widely explored. Various scaffold-free and scaffold-based strategies, such as monophasic, biphasic, and currently fabricated multiphasic and gradient architectures have been proposed and evaluated. Meanwhile, progenitor cells and tissue-specific cells have also been intensively investigated in vivo as well as ex vivo. Concerning bioactive factors and drugs, they have been combined with scaffolds and/or living cells, and even released in a spatiotemporally controlled manner. Although tremendous progress has been achieved, further research and development (R&D) is needed to convert preclinical outcomes into clinical applications. Here, the osteochondral unit structure, its defect classifications, and diagnosis are summarized. Commonly used clinical reparative techniques, tissue-engineered strategies, emerging 3D-bioprinting technologies, and the status of their clinical applications are discussed. Existing challenges to translation are also discussed and potential solutions for future R&D directions are proposed.

Protective effect of Moringa oleifera leaves ethanolic extract against thioacetamide-induced hepatotoxicity in rats via modulation of cellular antioxidant, apoptotic and inflammatory markers

The current study was conducted to evaluate the ameliorative and protective potentials of Moringea oleifera leaves ethanolic extract (MOLE) against thioacetamide (TAA) toxicity. A total of 58 male albino rats were randomly assigned into six experimental groups. G1, rats received distilled water. G2, rats were injected with a single dose of TAA (200 mg/kg BW) i.p. G3, rats were given MOLE (300 mg/kg BW) orally for 26 days. G4, rats were injected TAA as in G2 and treated with MOLE as G3. G5, rats were kept for 26 days without treatment then on day 27 injected with TAA as in G2. G6, rats were given MOLE for 26 days then on day 27 injected with TAA. Phytochemical analysis of MOLE indicated the presence of kaempferol, kaempferol malonylglucoside, kaempferol hexoside, kaempferol -3-O-glucoside, kaempferol-3-O-acetyl-glucoside, cyanidin -3-O-hexoside, ellagic acid, quercetin, quercetin-3-O-glucoside, and apigenin glucoside. Intoxication of rats with TAA significantly elevated activities of serum AST, ALT, and ALP; concentrations of malondialdehyde, nitric oxide, and hepatic tissue protein expression of caspase 3 and COX2 with alteration of the histological structures of hepatic tissues, while it decreased serum levels of total protein, albumin, and hepatic tissue contents of reduced glutathione. Also, TAA intoxication resulted in 62.5% mortality in rats of G5. Treatment of TAA intoxicated rats (G4) with MOLE ameliorated the toxic effects of TAA on hepatic tissue structure and function. It decreased serum activities of AST, ALT, and ALP; enhanced hepatic GSH concentration; reduced pathological alterations and lipid peroxidation; and downregulated caspase 3 and COX2 proteins expression in hepatic tissue. In addition, MOLE protected rats of G6 from TAA-induced hepatic tissues injury and dysfunction, and increased survival rate of rats. In conclusion, MOLE had both ameliorating and protecting potentials against TAA-induced rats liver damage through regulation of antioxidant, anti-apoptotic, and inflammatory biomarkers. Graphical abstract.

Artesunate alleviates interleukin‑1β‑induced inflammatory response and apoptosis by inhibiting the NF‑κB signaling pathway in chondrocyte‑like ATDC5 cells, and delays the progression of osteoarthritis in a mouse model

Osteoarthritis (OA) is a progressive and degenerative joint disorder that is highly prevalent worldwide and for which there is currently no effective medical therapy. Artesunate (ART), a natural compound used to treat malaria, possesses diverse biological properties, including the regulation of inflammation and apoptosis in various cells; however, its role in OA remains unclear. The aim of the present study was to investigate the effects of ART on interleukin (IL)‑1β‑induced chondrocyte‑like ATDC5 cells and in an OA mouse model. The results revealed that ART dose‑dependently relieved the inhibitory effect of IL‑1β on cell viability. Moreover, ART significantly reduced the overexpression of matrix metalloproteinase (MMP)‑3, MMP‑13, a disintegrin and metalloproteinase with thrombospondin motifs‑5 and cyclooxygenase‑2 at both the gene and protein levels in chondrocyte‑like ATDC5 cells stimulated by IL‑1β. Furthermore, ART decreased the expression of pro‑apoptotic Bax, cleaved caspase‑3 and cleaved caspase‑7 in a dose‑dependent manner, and increased the expression of the anti‑apoptotic factor Bcl‑2. These changes were mediated by the inhibitory effect of ART on the nuclear factor‑κB signaling pathway, defined as repression of the phosphorylation of IκBα and p65, and improved redistribution of p65. Additionally, ART blocked the advancement of the calcified cartilage zone and the loss of proteoglycan, and lowered histological scoring of OA in a mouse model. Taken together, these results indicate that ART may be of value as a therapeutic agent for OA.

IL-1β receptor antagonist (IL-1Ra) combined with autophagy inducer (TAT-Beclin1) is an effective alternative for attenuating extracellular matrix degradation in rat and human osteoarthritis chondrocytes

Background

Autophagy induction is an effective approach for OA therapy. IL-1β is one of the major inflammatory cytokines linked to OA pathological progression, and its receptor blockade interrupts OA cartilage destruction. The objective of this study was to decipher the link between autophagy and regulatory mechanism of IL-1β and to investigate the effect of IL-1β receptor blockade by IL-1 receptor antagonist (IL-1Ra) combined with or without an autophagy inducer (TAT-Beclin1) on extracellular matrix (ECM) in OA chondrocytes in vitro and in vivo.

Methods

IL-1β-treated rat and human OA chondrocytes were cultured in response to IL-1Ra. The expression and distribution of signal molecules regulating ECM synthesis and autophagy were investigated via western blotting, immunoprecipitation, real-time PCR, immunofluorescence, and transmission electron microscope technique. Furthermore, after intra-articular injection of IL-1Ra, TAT-Beclin1, and a combination of both in a rat OA model established by anterior cruciate ligament transection and medial meniscus resection, the morphological changes of cartilage and related signal molecule expression levels were monitored using H.E., Safranin O-Fast green, and immunohistochemistry staining.

Results

Reduced autophagy by IL-1β contributed to ECM degradation, and blockade of IL-1β by IL-1Ra restored autophagy and attenuated ECM degradation in rat and human OA chondrocytes, as well as in a rat OA model. Akt/mTOR/ULK1, Akt/mTOR/NF-κB, and LC3B deacetylation were involved in autophagy regulated by IL-1β. Intra-articular injection of IL-1Ra combined with TAT-Beclin1 was more effective than IL-1Ra alone.

Conclusions

IL-1Ra restored autophagy and attenuated ECM degradation, with an implication that blocking IL-1β combined with enhancing autophagy might be a potential therapeutic strategy for OA.

Electronic supplementary material

The online version of this article (10.1186/s13075-019-1952-5) contains supplementary material, which is available to authorized users.

Functional Biomolecule Delivery Systems and Bioengineering in Cartilage Regeneration

Osteoarthritis (OA) is a common degenerative disease which involves articular cartilage, and leads to total joint disability in the advanced stages. Due to its avascular and aneural nature, damaged cartilage cannot regenerate itself. Stem cell therapy and tissue engineering represent a promising route in OA therapy, in which cooperation of mesenchymal stem cells (MSCs) and three-dimensional (3D) scaffolds contribute to cartilage regeneration. However, this approach still presents some limits such as poor mechanical properties of the engineered cartilage. The natural dynamic environment of the tissue repair process involves a collaboration of several signals expressed in the biological system in response to injury. For this reason, tissue engineering involving exogenous "influencers" such as mechanostimulation and functional biomolecule delivery systems (BDS), represent a promising innovative approach to improve the regeneration process. BDS provide a controlled release of biomolecules able to interact between them and with the injured tissue. Nano-dimensional BDS is the future hope for the design of personalized scaffolds, able to overcome the delivery problems. MSC-derived extracellular vesicles (EVs) represent an attractive alternative to BDS, due to their innate targeting abilities, immunomodulatory potential and biocompatibility. Future advances in cartilage regeneration should focus on multidisciplinary strategies such as modular assembly strategies, EVs, nanotechnology, 3D biomaterials, BDS, mechanobiology aimed at constructing the functional scaffolds for actively targeted biomolecule delivery. The aim of this review is to run through the different approaches adopted for cartilage regeneration, with a special focus on biomaterials, BDS and EVs explored in terms of their delivery potential, healing capabilities and mechanical features.

Recently highlighted nutraceuticals for preventive management of osteoarthritis

Osteoarthritis (OA) is a chronic degenerative disease of articular cartilage with limited treatment options. This reality encourages clinicians to suggest preventive measures to delay and contain the outbreak of the pathological conditions. Articular cartilage and synovium suffering from OA are characterised by an inflammatory state and by significant oxidative stress, responsible for pain, swelling and loss of mobility in the advanced stages. This review will focus on the ability of olive oil to exert positive effects on the entire joint to reduce pro-inflammatory cytokine release and increase lubricin synthesis, olive leaf extract, since it maintains lubrication by stimulating high molecular weight hyaluronan synthesis in synovial cells, curcumin, which delays the start of pathological cartilage breakdown, sanguinarine, which downregulates catabolic proteases, vitamin D for its capacity to influence the oxidative and pro-inflammatory environment, and carnosic acid as an inducer of heme oxygenase-1, which helps preserve cartilage degeneration. These molecules, considered as natural dietary supplements, appear like a cutting-edge answer to this tough health problem, playing a major role in controlling homeostatic balance loss and slowing down the pathology progression. Natural or food-derived molecules that are able to exert potential therapeutic effects are known as “nutraceutical”, resulting from the combination of the words “nutrition” and “pharmaceutical”. These compounds have gained popularity due to their easy availability, which represents a huge advantage for food and pharmaceutical industries. In addition, the chronic nature of OA implies the use of pharmacological compounds with proven long-term safety, especially because current treatments like nonsteroidal anti-inflammatory drugs and analgesics improve pain relief but have no effect on degenerative progression and can also cause serious side effects.

Early intervention of swimming exercises attenuate articular cartilage destruction in a rat model of anterior cruciate ligament and meniscus knee injuries

AIM

The anterior cruciate ligament (ACL) and meniscus injuries often cause post-traumatic knee osteoarthritis (PTOA), which can place great limitations on patients. But to date there is no effective therapy to delay the progression of cartilage destruction in PTOA. This study aimed to compare the effects of early versus delayed swimming exercise on the chondroprotective effects in a rat PTOA model with ACL and meniscus injuries.

MAIN METHODS

Thirty-two adult male Sprague-Dawley rats received unilateral ACL transection and medial meniscectomy (ACLMT). These were randomly allocated to four groups: early swimming (eSW), delayed swimming (dSW), sham-operated early swimming (sham-eSW) and sham-operated delayed swimming (sham-dSW). Swimming (30 min per session) continuing for 28 days was started three days and three months after ACLMT surgery as a protocol for eSW and dSW intervention. Cartilage quality was assessed by Mankin HHGS examination (H&E, Safranin-O stain) and collagen type II (CoII) and matrix metalloproteases-13 (MMP13) immunohistochemistry.

KEY FINDINGS

ACLMT induced the PTOA histopathological changes, inhibited CoII and enhanced MMP13 expressions in cartilage for both sham-eSW and sham-dSW groups. eSW intervention significantly enhanced CoII expression and suppressed MMP13 overexpression in superficial and transitional zones of cartilage, as well as better Mankin scores, corresponding to sham-swimming controls (P < 0.05). dSW intervention provided less enhancement of CoII expression and improvement of histopathological scoring, but significantly reduced MMP13 overexpression compared to animals in eSW (P < 0.05).

SIGNIFICANCE

Early intervention by swimming at very early stages of cartilage damage provides greater benefits than delayed intervention when PTOA has already developed.

Association of Parkinson Disease Induction with Cardiac Upregulation of Apoptotic Mediators P53 and Active Caspase-3: An Immunohistochemistry Study

BACKGROUND Apoptosis plays a key role in the pathogenesis of Parkinson disease (PD). Active caspase-3, which is a proapoptotic factor, has been shown to reduce cardiac contractility, causing cardiac dysfunction in many pathological diseases. Reduced cardiac contractility and cardiac autonomic dysfunction have been reported in PD patients and PD mice treated with MPTP. The aim of this study was to show the impact of PD induction on the expression of the apoptotic mediators p53 and active caspase-3 in the heart. MATERIAL AND METHODS Equal control and PD groups were formed by 20 randomly selected normal albino mice. We used 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (25 mg/kg) and probenecid (250 mg/kg) (MPTP/p) to induce chronic Parkinsonism in the PD group. Immunohistochemistry was performed to investigate the expression of p53, active caspase-3, and β-adrenergic receptor in hearts from the 2 animal groups. RESULTS P53 and active caspase-3 expression was significantly higher in PD hearts than in the control hearts (p value <0.01). β-adrenergic receptor expression was significantly lower in PD hearts than in control hearts (p value <0.01). CONCLUSIONS Our results show an association of PD with p53 and active caspase-3 overexpression and β-adrenergic receptor underexpression in the heart, potentially promoting the cardiac autonomic dysfunction frequently observed in PD.

Origin and Efficacy of Hyaluronan Injections in Knee Osteoarthritis: Randomized, Double-Blind Trial

BACKGROUND Several hyaluronan preparations are available that have different dosage forms, origins, and concentrations. The objective of the study was to compare the efficacy of intra-articular chemically cross-linked hyaluronan (CCH) and avian-derived hyaluronan (ADH) injections in knee osteoarthritis (KOA) patients. MATERIAL AND METHODS In total, 258 patients were randomized into 2 groups of 129 each: patients who received CCH injection (CCH group) and patients who received ADH injection (ADH group). Radiographic Kellgren-Lawrence score, visual analog scale (VAS) pain score, Lequesne index score, the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index, single-limb stance (SLS) test, and timed "Up-and-Go" (TUG) test were performed. The Mann-Whitney U test or independent t-test following Bonferroni adjustment was performed for statistical analysis at 95% of confidence level. RESULTS The CCH group had improved VAS pain score (P<0.0001, q=54.803), total WOMAC score (P<0.0001, q=4.753), Lequesne index score (P<0.0001, q=3.208), and SLS time (P<0.0001, q=8.76) at the end of 6 months as compared to those in the ADH group. After 6 months of follow-up, the ADH group had improved TUG time (P=0.0148, q=3.385) as compared to baseline. Both groups of patients had the similar improvement in Kellgren-Lawrence score and mild to moderate adverse effects after 6 months. CONCLUSIONS CCH injection was superior to ADH injection.

Using the interplay of magnetic guidance and controlled TGF-β release from protein-based nanocapsules to stimulate chondrogenesis

Introduction

Stimulating the proliferation and differentiation of chondrocytes for the regeneration of articular cartilage is a promising strategy, but it is currently ineffective. Although both physical stimulation and growth factors play important roles in cartilage repair, their interplay remains unclear and requires further investigation. In this study, we aimed to clarify their contribution using a magnetic drug carrier that not only can deliver growth factors but also provide an external stimulation to cells in the two-dimensional environment.

Materials and methods

We developed a nanocapsule (transforming growth factor-β1 [TGF-β1]-loaded magnetic amphiphilic gelatin nanocapsules [MAGNCs]; TGF-β1@MAGNCs) composed of hexanoic-anhydride-grafted gelatin and iron oxide nanoparticles to provide a combination treatment of TGF-β1 and magnetically induced physical stimuli. With the expression of Arg-Gly-Asp peptide in the gelatin, the TGF-β1@MAGNCs have an inherent affinity for chondrogenic ATDC5 cells.

Results

In the absence of TGF-β1, ATDC5 cells treated with a magnetic field show significantly upregulated Col2a1 expression. Moreover, TGF-β1 slowly released from biodegradable TGF-β1@ MAGNCs further improves the differentiation with increased expression of Col2a1 and Aggrecan.

Conclusion

Our study shows the time-dependent interplay of physical stimuli and growth factors on chondrogenic regeneration, and demonstrates the promising use of TGF-β1@MAGNCs for articular cartilage repair.

Chondroprotective effects of aqueous extract of Anthriscus sylvestris leaves on osteoarthritis in vitro and in vivo through MAPKs and NF-κB signaling inhibition

Osteoarthritis (OA) is a common degenerative joint disease, characterized by cartilage degradation and inflammation, in the elderly population. Anthriscus sylvestris has been used in Korean traditional medicine and contains many polyphenolic compounds such as cynaroside and chlorogenic acid, which are major active components responsible for its antioxidant effect. In this study, we aimed to evaluate the chondroprotective effect of an aqueous extract of A. sylvestris leaves (AE-ASL) on OA, both in vitro and in vivo. Rat primary chondrocytes were pretreated with AE-ASL for 1 h before interleukin-1β (20 ng/mL) stimulation. The production of nitrite, PGE₂, aggrecan, and collagen type II were detected by Griess reagent and ELISAs. The mRNA levels of iNOS, COX-2, MMP-3, and MMP-13 were measured by RT-PCR. In addition, protein levels of iNOS, COX-2, MMP-3, MMP-13, ADAMTS-4, MAPKs, and NF-κB p65 subunit were measured by western blot analysis. Sulfated glycosaminoglycan (sGAGs) were detected by dimethylmethylene blue (DMMB) assay. During in vivo study, the effects of AE-ASL were evaluated for 8 weeks in a rat model of destabilization of the medial meniscus (DMM) surgery-induced OA. AE-ASL significantly inhibited expression of nitrite, iNOS, PGE₂, COX-2, MMP-3, MMP-13, and ADAMTS-4 in IL-1β-stimulated chondrocytes. Moreover, it decreased the IL-1β-induced degradation of aggrecan, collagen type II, and proteoglycan. In addition, AE-ASL suppressed IL-1β-induced phosphorylation of MAPKs and NF-κB p65 subunit translocation to nucleus. In vivo, AE-ASL inhibited DMM surgery-induced cartilage destruction and proteoglycan loss. Taken together, these results suggest that AE-ASL may be a potential therapeutic agent for the alleviation of OA progression.

Impact of Western and Mediterranean Diets and Vitamin D on Muscle Fibers of Sedentary Rats

Background: The metabolic syndrome is associated with sarcopenia. Decreased serum levels of Vitamin D (VitD) and insulin-like growth factor (IGF)-1 and their mutual relationship were also reported. We aimed to evaluate whether different dietary profiles, containing or not VitD, may exert different effects on muscle molecular morphology. Methods: Twenty-eight male rats were fed for 10 weeks in order to detect early defects induced by different dietary regimens: regular diet (R); regular diet with vitamin D supplementation (R-DS) and regular diet with vitamin D restriction (R-DR); high-fat butter-based diets (HFB-DS and HFB-DR) with 41% energy from fat; high-fat extra-virgin olive oil-based diets (HFEVO-DS and HFEVO-DR) with 41% energy from fat. IL-1β, insulin-like growth factor (IGF)1, Dickkopf-1 (DKK-1), and VitD-receptor (VDR) expressions were evaluated by immunohistochemistry. Muscle fiber perimeter was measured by histology and morphometric analysis. Results: The muscle fibers of the HEVO-DS rats were hypertrophic, comparable to those of the R-DS rats. An inverse correlation existed between the dietary fat content and the perimeter of the muscle fibers (p < 0.01). In the HFB-DR rats, the muscle fibers appeared hypotrophic with an increase of IL-1β and a dramatic decrease of IGF-1 expression. Conclusions: High-fat western diet could impair muscle metabolism and lay the ground for subsequent muscle damage. VitD associated with a Mediterranean diet showed trophic action on the muscle fibers.

Physical activity and Mediterranean diet based on olive tree phenolic compounds from two different geographical areas have protective effects on early osteoarthritis, muscle atrophy and hepatic steatosis

PURPOSE

Osteoarthitis (OA) leads to progressive loss of articular cartilage, pain and joint disability. An acute injury constitutes an important risk factor for early OA, determining an inflammatory process responsible of cartilage degeneration and muscle atrophy, due to the joint pain and immobility. The study aims to assess the effects of conjugation of physical activity and diet enriched by olive tree compounds [extra virgin olive oil (EVOO) and olive leaf extract (OLE)], on the musculoskeletal system in OA rat model.

METHODS

OA was induced by anterior cruciate ligament transection and confirmed by Mankin and OARSI scores. Rats were subjected to physical activity on treadmill 5 days a week for 10 min daily and fed with experimental diets (standard diet enriched with Sicilian EVOO, Tunisian EVOO and Tunisian EVOO-OLE) for 12 weeks. Immunohistochemistry was used to evaluate IL-6 and lubricin expression in cartilage tissue and ELISA was used to quantify these proteins in serum at different time points. Histology and histomorphometry analysis were done to valuate liver steatosis, muscle atrophy and cartilage pathological changes.

RESULTS

Compared to the OA group, the experimental groups showed general increased lubricin and decreased IL-6 expression, significant muscle hypertrophy and no signs of liver steatosis, suggesting the beneficial effects of physical activity coupled with EVOO-enriched diets on rat articular cartilage. Interestingly, the best result was shown for Sicilian EVOO-enriched diet.

CONCLUSION

In conclusion, the conjugation of physical activity and EVOO-enriched diet determines a significant articular cartilage recovery process in early OA.

NLRP1 and NLRP3 inflammasomes mediate LPS/ATP‑induced pyroptosis in knee osteoarthritis

Pyroptosis is triggered by inflammasomes after its activation by various inflammatory stimulations, including lipopolysaccharide (LPS) and improper pH. This may result in programmed death of the affected cell. It is well known that NLRP1 and NLRP3 inflammasomes mediate the production of various cytokines in inflammatory disorders; however, it is still unknown whether NLRP1 and NLRP3 inflammasomes can influence the LPS‑induced pyroptosis in the progression of knee osteoarthritis (KOA). In the present study, the correlation between the NLRP inflammasomes and fibroblast‑like synoviocytes (FLSs) pyroptosis was investigated in vivo and in vitro. Human synovial samples were collected from KOA patients and the expression of NLRP1 and NLRP3 inflammasomes was analyzed. Human FLS were isolated in vitro and stimulated with LPS. To determine whether NLRP1 and NLRP3 inflammasomes are involved in FLS pyroptosis, NLRP1 and NLRP3 small interfering RNAs (siRNAs) were used. The results showed that the expression of NLRPs and inflammasome‑related proteins were upregulated and FLS stimulated with LPS+ATP resulted in cell pyroptosis. However, LPS+ATP‑induced pyroptosis was attenuated by NLRP1 and NLRP3 siRNAs. The results of the present study indicate that LPS‑induced FLS pyroptosis may be mediated by either NLRP1 or NLRP3 inflammsomes. Overall, based on the data obtained from patients and in vitro cells, the present finsings showed that NLRP1 and NLRP3 inflammasomes are highly involved in the FLS inflammation and pyroptosis. Furthermore, inhibition of NLRP1 and NLRP3 led to a remarkable reduction of pyroptosis‑related cytokines. Thus, NLRP1 and NLRP3 inflammasomes may be important in the pathogenesis of OA and may represent a novel therapeutic target.

LOX-1 deficient mice show resistance to zymosan-induced arthritis

Recent data suggest that the lectin-like oxidized low-density lipoprotein (ox-LDL) receptor-1 (LOX-1)/ox-LDL system may be involved in the pathogenesis of arthritis. We aimed to demonstrate the roles of the LOX- 1/ox-LDL system in arthritis development by using LOX-1 knockout (KO) mice. Arthritis was induced in the right knees of C57Bl/6 wild-type (WT) and LOX-1 KO mice via zymosan injection. Saline was injected in the left knees. Arthritis development was evaluated using inflammatory cell infiltration, synovial hyperplasia, and cartilage degeneration scores at 1, 3, and 7 days after administration. LOX-1, ox-LDL, and matrix metalloproteinase-3 (MMP-3) expression in the synovial cells and chondrocytes was evaluated by immunohistochemistry. The LOX-1, ox-LDL, and MMP-3 expression levels in synovial cells were scored on a grading scale. The positive cell rate of LOX-1, ox-LDL, and MMP-3 in chondrocytes was measured. The correlation between the positive cell rate of LOX-1 or ox-LDL and the cartilage degeneration score was also examined. Inflammatory cell infiltration, synovial hyperplasia, and cartilage degeneration were significantly reduced in the LOX-1 KOmice with zymosan-induced arthritis (ZIA) compared to WT mice with ZIA. In the saline-injected knees, no apparent arthritic changes were observed. LOX-1 and ox-LDL expression in synovial cells and chondrocytes were detected in the knees of WT mice with ZIA. No LOX-1 and ox-LDL expression was detected in the knees of LOX-1 KO mice with ZIA or the salineinjected knees of both mice. MMP-3 expression in the synovial cells and chondrocytes was also detected in knees of both mice with ZIA, and was significantly less in the LOX-1 KO mice than in WT mice. The positive cell rate of LOX-1 or ox-LDL and the cartilage degeneration score showed a positive correlation. Our data show the involvement of the LOX-1/ox-LDL system in murine ZIA development. LOX-1-positive synovial cells and chondrocytes are potential therapeutic targets for arthritis prevention.

A Novel Human-Like Collagen Hydrogel Scaffold with Porous Structure and Sponge-Like Properties

The aim of this research was to prepare a novel sponge-like porous hydrogel scaffold based on human-like collagen (HLC) that could be applied in cartilage tissue regeneration. In this study, bovine serum albumin (BSA) was used as a porogen to prepare the porous hydrogel, which had not been previously reported. Glutamine transaminase (TGase) was used as the cross-linker of the hydrogel, because it could catalyze the cross-linking of BSA. During the crosslinking process, BSA and HLC were mixed together, which affected the cross-linking of HLC. When the cross-linking was completed, the non-crosslinked section formed pores. The microstructure, porosity, swelling properties, and compressive properties of the hydrogel were studied. The results showed that the pore size of the hydrogel was between 100 and 300 μm, the porosity reached up to 93.43%, and the hydrogel had rapid water absorption and suitable mechanical properties. Finally, we applied the hydrogel to cartilage tissue engineering through in vitro and in vivo research. The in vitro cell experiments suggested that the hydrogel could promote the proliferation and adhesion of chondrocytes, and in vivo transplantation of the hydrogel could enhance the repair of cartilage. In general, the hydrogel is promising as a tissue engineering scaffold for cartilage.

Clinical evidence of traditional vs fast track recovery methodologies after total arthroplasty for osteoarthritic knee treatment. A retrospective observational study

BACKGROUND

During the last years, programs to enhance postoperative recovery and decrease morbidity after total knee arthroplasty, have been developed across a variety of surgical procedures and referred to as "Fast-Track Surgery". In this study we aimed to find some answers in the management of osteoarthritic patients subjected to total knee arthroplasty, by using the Fast-Track methodology. To this purpose we evaluated parameters such as early mobilization of patients, better pain management, bleeding, possible complications, reduced hospitalization time, an overall improved recovery and patient satisfaction.

METHODS

132 patients were selected, of which, 95 treated with "Fast Track" method and 37 treated with traditional method (control group). All the patients were hospitalized and underwent the same rehabilitation program for the first three days after surgery.

RESULTS

In both groups, the parameters of pain and deformity demonstrated the most rapid improvement, while those of function and movement were normalized as gradual and progressive improvement over the next 2 months. The different functional test used (Barthel, MRC, VAS) showed that the mean values were significantly greater in Fast Track group when compared to the control.

CONCLUSION

The results of the study confirm that the application of the Fast Track protocol in orthopaedics after total knee replacement results in rapid post-surgery recovery.

LEVEL OF EVIDENCE

IV. Case series, low-quality cohort or case-control studies.

Engineered cartilage regeneration from adipose tissue derived-mesenchymal stem cells: A morphomolecular study on osteoblast, chondrocyte and apoptosis evaluation

The poor self-repair capacity of cartilage tissue in degenerative conditions, such as osteoarthritis (OA), has prompted the development of a variety of therapeutic approaches, such as cellular therapies and tissue engineering based on the use of mesenchymal stem cells (MSCs). The aim of this study is to demonstrate, for the first time, that the chondrocytes differentiated from rat adipose tissue derived-MSCs (AMSCs), are able to constitute a morphologically and biochemically healthy hyaline cartilage after 6 weeks of culture on a Collagen Cell Carrier (CCC) scaffold. In this study we evaluated the expression of some osteoblasts (Runt-related transcription factor 2 (RUNX2) and osteocalcin), chondrocytes (collagen I, II and lubricin) and apoptosis (caspase-3) biomarkers in undifferentiated AMSCs, differentiated AMSCs in chondrocytes cultured in monolayer and AMSCs-derived chondrocytes seeded on CCC scaffolds, by different techniques such as immunohistochemistry, ELISA, Western blot and gene expression analyses. Our results showed the increased expression of collagen II and lubricin in AMSCs-derived chondrocytes cultured on CCC scaffolds, whereas the expression of collagen I, RUNX2, osteocalcin and caspase-3 resulted decreased, when compared to the controls. In conclusion, this innovative basic study could be a possible key for future therapeutic strategies for articular cartilage restoration through the use of CCC scaffolds, to reduce the morbidity from acute cartilage injuries and degenerative joint diseases.

RETRACTED: Polar and apolar extra virgin olive oil and leaf extracts as a promising anti-inflammatory natural treatment for osteoarthritis

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Authors. An anonymous reader made the authors aware of potential errors in the presentation and the experimental design for the Western blot data in Figure 3. Upon thorough investigation the authors concluded that in fact, in addition to an honest error (wrong image selected for inclusion into the article), the experimental design was not state-of-the-art in that the loading controls were run on parallel gels rather than on the gels to be probed for iNOS and collagen II. Therefore, in order to avoid any potentially wrong conclusions, the authors decided to retract the article, to confirm the data in a separate series of experiments and to submit the manuscript again after proper confirmation of the results and conclusions. The authors thank the anonymous reader, who spotted this error, and apologize for any inconvenience caused.

Conditional Deletion of the Phd2 Gene in Articular Chondrocytes Accelerates Differentiation and Reduces Articular Cartilage Thickness

Based on our findings that PHD2 is a negative regulator of chondrocyte differentiation and that hypoxia signaling is implicated in the pathogenesis of osteoarthritis, we investigated the consequence of disruption of the Phd2 gene in chondrocytes on the articular cartilage phenotype in mice. Immunohistochemistry detected high expression of PHD2 in the superficial zone (SZ), while PHD3 and HIF-1α (target of PHD2) are mainly expressed in the middle-deep zone (MDZ). Conditional deletion of the Phd2 gene (cKO) in chondrocytes accelerated the transition of progenitors to hypertrophic (differentiating) chondrocytes as revealed by reduced SZ thickness, and increased MDZ thickness, as well as increased chondrocyte hypertrophy. Immunohistochemistry further revealed decreased levels of progenitor markers but increased levels of hypertrophy markers in the articular cartilage of the cKO mice. Treatment of primary articular chondrocytes, in vitro, with IOX2, a specific inhibitor of PHD2, promoted articular chondrocyte differentiation. Knockdown of Hif-1α expression in primary articular chondrocytes using lentiviral vectors containing Hif-1α shRNA resulted in reduced expression levels of Vegf, Glut1, Pgk1, and Col10 compared to control shRNA. We conclude that Phd2 is a key regulator of articular cartilage development that acts by inhibiting the differentiation of articular cartilage progenitors via modulating HIF-1α signaling.

Lectin-like, oxidized low-density lipoprotein receptor-1-deficient mice show resistance to age-related knee osteoarthritis

The lectin-like, oxidized low-density lipoprotein (ox-LDL) receptor-1 (LOX-1)/ox-LDL system contributes to atherosclerosis and may be involved in cartilage degeneration. The purpose of this study was to determine whether the LOX-1/ox-LDL system contributes to age-related osteoarthritis (OA) in vivo, using LOX-1 knockout (LOX-1 KO) mice. Knee cartilage from 6, 12, and 18-month old (n = 10/group) C57Bl/6 wild-type (WT) and LOX-1 KO mice was evaluated by determining the Osteoarthritis Research Society International (OARSI) score of Safranin-O stained samples. The prevalence of knee OA in both mouse strains was also investigated. Expression levels of LOX-1, ox-LDL, runt-related transcription factor-2 (Runx2), type-X collagen (COL X), and matrix metalloproteinase-13 (MMP-13) in the articular chondrocytes were analyzed immunohistologically. No significant difference was observed in the mean scores of WT (2.00±0.61) and LOX-1 KO mice (2.00±0.49) at 6 months of age (P=1.00, n=10). At 12 and 18 months of age, the mean scores of LOX-1 KO mice (3.75±0.93 and 5.50±0.78) were significantly lower than those of WT mice (5.25±1.14 and 9.00±1.01; P<0.001 in both cases; n=10). The prevalence of OA in LOX-1 KO mice was lower than that in WT mice at 12 and 18 months of age (40 vs 70%, 70 vs 90%, respectively; n=10). The expression levels of Runx2, COL X, and MMP-13 in articular chondrocytes significantly decreased in LOX-1 KO, mice compared with those in WT mice. The study indicated that the LOX-1/ox-LDL system in chondrocytes plays a role in the pathogenesis of age-related knee OA, which is potentially a target for preventing OA progression.

Is there still room for novelty, in histochemical papers?

Histochemistry continues to be widely applied in biomedical research, being nowadays mostly addressed to detect and locate single molecules or molecular complexes inside cells and tissues, and to relate structural organization and function at the high resolution of the more advanced microscopical techniques. In the attempt to see whether histochemical novelties may be found in the recent literature, the articles published in the European Journal of Histochemistry in the period 2014-2016 have been reviewed. In the majority of the published papers, standardized methods have been preferred by scientists to make their results reliably comparable with the data in the literature, but several papers (approximately one fourth of the published articles) described novel histochemical methods and procedures. It is worth noting that there is a growing interest for minimally-invasive in vivo techniques (magnetic resonance imaging, autofluorescence spectroscopy), which may parallel conventional histochemical analyses to acquire evidence not only on the morphological features of living organs and tissues, but also on their functional, biophysical and molecular characteristics. Thanks to this unceasing methodological refinement, histochemistry will continue to provide innovative applications in the biomedical field.

Chitotriosidase: A New Inflammatory Marker in Diabetic Complications

Chitotriosidase (CHIT1) belongs to chitinase family. So far this enzyme has been the best investigated human chitinase regarding its biological activity and association with various disorders. In a healthy population, CHIT1 activity is very low and originates in the circulating polymorphonuclear cells. Conversely, during the development of acute/chronic inflammatory disorders, the enzymatic activity of CHIT1 increases significantly. Recently, CHIT1 has also been involved in the pathogenesis of diabetes mellitus (DM). Mounting evidence from experimental studies revealing the increase of CHIT1 levels in pathological conditions, such as atherosclerosis, coronary artery disease, acute ischemic stroke, cerebrovascular dementia, nonalcoholic fatty liver disease, and osteolytic processes suggest its critical role in the evolutions and complications of DM. This review is addressed to provide mechanistic insights by highlighting the relationship between CHIT1 and diabetes, and their contribution in the exacerbation of this disease.

Co-Expression and Co-Localization of Cartilage Glycoproteins CHI3L1 and Lubricin in Osteoarthritic Cartilage: Morphological, Immunohistochemical and Gene Expression Profiles

Osteoarthritis is the most common human arthritis characterized by degeneration of articular cartilage. Several studies reported that levels of human cartilage glycoprotein chitinase 3-like-1 (CHI3L1) are known as a potential marker for the activation of chondrocytes and the progression of Osteoarthritis (OA), whereas lubricin appears to be chondroprotective. The aim of this study was to investigate the co-expression and co-localization of CHI3L1 and lubricin in normal and osteoarthritic rat articular cartilage to correlate their modified expression to a specific grade of OA. Samples of normal and osteoarthritic rat articular cartilage were analyzed by the Kellgren–Lawrence OA severity scores, the Kraus’ modified Mankin score and the Histopathology Osteoarthritis Research Society International (OARSI) system for histomorphometric evaluations, and through CHI3L1 and lubricin gene expression, immunohistochemistry and double immuno-staining analysis. The immunoexpression and the mRNA levels of lubricin increased in normal cartilage and decreased in OA cartilage (normal vs. OA, p < 0.01). By contrast, the immunoexpression and the mRNA levels of CHI3L1 increased in OA cartilage and decreased in normal cartilage (normal vs. OA, p < 0.01). Our findings are consistent with reports suggesting that these two glycoproteins are functionally associated with the development of OA and in particular with grade 2/3 of OA, suggesting that in the future they could be helpful to stage the severity and progression of the disease.

Histochemistry in biology and medicine: a message from the citing journals

Especially in recent years, biomedical research has taken advantage of the progress in several disciplines, among which microscopy and histochemistry. To assess the influence of histochemistry in the biomedical field, the articles published during the period 2011-2015 have been selected from different databases and grouped by subject categories: as expected, biological and biomedical studies where histochemistry has been used as a major experimental approach include a wide of basic and applied researches on both humans and other animal or plant organisms. To better understand the impact of histochemical publications onto the different biological and medical disciplines, it was useful to look at the journals where the articles published in a multidisciplinary journal of histochemistry have been cited: it was observed that, in the five-years period considered, 20% only of the citations were in histochemical periodicals, the remaining ones being in journals of Cell &amp; Tissue biology,  general and experimental Medicine, Oncology, Biochemistry &amp; Molecular biology, Neurobiology, Anatomy &amp; Morphology, Pharmacology &amp; Toxicology, Reproductive biology, Veterinary sciences, Physiology, Endocrinology, Tissue engineering &amp; Biomaterials,  as well as in multidisciplinary journals.It is easy to foresee that also in the future the histochemical journals will be an attended forum for basic and applied scientists in the biomedical field. It will be crucial that these journals be open to an audience as varied as possible, publishing articles on the application of refined techniques to very different experimental models: this will stimulate non-histochemist scientists to approach histochemistry whose application horizon could expand to novel and possibly exclusive subjects.

Effects of exercise on physical limitations and fatigue in rheumatic diseases

Physical activity covers not just sports but also simple everyday movements such as housework, walking and playing. Regular exercise has a great importance in maintaining good health, indeed inactivity is a risk factor for different chronic diseases. Physical exercise can play a crucial role in the treatment of rheumatic diseases, optimizing both physical and mental health, enhancing energy, decreasing fatigue and improving sleep. An exercise program for patients with rheumatic diseases aims to preserve or restore a range of motion of the affected joints, to increase muscle strength and endurance, and to improve mood and decrease health risks associated with a sedentary lifestyle. In this editorial I describe the benefits of the exercise on physical limitations and fatigue in rheumatic diseases that seem to have a short and long-term effectiveness. A literature review was conducted on PubMed, Scopus and Google Scholar using appropriate keywords based on the present editorial.

Comprehensive analysis of translational osteochondral repair: Focus on the histological assessment

Articular cartilage guarantees for an optimal functioning of diarthrodial joints by providing a gliding surface for smooth articulation, weight distribution, and shock absorbing while the subchondral bone plays a crucial role in its biomechanical and nutritive support. Both tissues together form the osteochondral unit. The structural assessment of the osteochondral unit is now considered the key standard procedure for evaluating articular cartilage repair in translational animal models. The aim of this review is to give a detailed overview of the different methods for a comprehensive evaluation of osteochondral repair. The main focus is on the histological assessment as the gold standard, together with immunohistochemistry, and polarized light microscopy. Additionally, standards of macroscopic, non-destructive imaging such as high resolution MRI and micro-CT, biochemical, and molecular biological evaluations are addressed. Potential pitfalls of analysis are outlined. A second focus is to suggest recommendations for osteochondral evaluation.

Biomarkers of Chondrocyte Apoptosis and Autophagy in Osteoarthritis

Cell death with morphological and molecular features of apoptosis has been detected in osteoarthritic (OA) cartilage, which suggests a key role for chondrocyte death/survival in the pathogenesis of OA. Identification of biomarkers of chondrocyte apoptosis may facilitate the development of novel therapies that may eliminate the cause or, at least, slow down the degenerative processes in OA. The aim of this review was to explore the molecular markers and signals that induce chondrocyte apoptosis in OA. A literature search was conducted in PubMed, Scopus, Web of Science and Google Scholar using the keywords chondrocyte death, apoptosis, osteoarthritis, autophagy and biomarker. Several molecules considered to be markers of chondrocyte apoptosis will be discussed in this brief review. Molecular markers and signalling pathways associated with chondroycte apoptosis may turn out to be therapeutic targets in OA and approaches aimed at neutralizing apoptosis-inducing molecules may at least delay the progression of cartilage degeneration in OA.

Somitogenesis: From somite to skeletal muscle

Myogenesis is controlled by an elaborate system of extrinsic and intrinsic regulatory mechanisms in all development stages. The aim of this review is to provide an overview of the different stages of myogenesis and muscle differentiation in mammals, starting from somitogenesis and analysis of the different portions that constitute the mature somite. Particular attention was paid to regulatory genes, in addition to mesodermal stem cells, which represent the earliest elements of myogenesis. Finally, the crucial role of growth factors, molecules of vital importance in contractile regulation, hormones and their function in skeletal muscle differentiation, growth and metabolism, and the role played by central nervous system, are discussed.

Osteoarthritis in the XXIst century: risk factors and behaviours that influence disease onset and progression

Osteoarthritis (OA) is a growing public health problem across the globe, affecting more than half of the over 65 population. In the past, OA was considered a wear and tear disease, leading to the loss of articular cartilage and joint disability. Nowadays, thanks to advancements in molecular biology, OA is believed to be a very complex multifactorial disease. OA is a degenerative disease characterized by “low-grade inflammation” in cartilage and synovium, resulting in the loss of joint structure and progressive deterioration of cartilage. Although the disease can be dependent on genetic and epigenetic factors, sex, ethnicity, and age (cellular senescence, apoptosis and lubricin), it is also associated with obesity and overweight, dietary factors, sedentary lifestyle and sport injuries. The aim of this review is to highlight how certain behaviors, habits and lifestyles may be involved in the onset and progression of OA and to summarize the principal risk factors involved in the development of this complicated joint disorder.

Ameliorative effects of PACAP against cartilage degeneration. Morphological, immunohistochemical and biochemical evidence from in vivo and in vitro models of rat osteoarthritis

Osteoarthritis (OA); the most common form of degenerative joint disease, is associated with variations in pro-inflammatory growth factor levels, inflammation and hypocellularity resulting from chondrocyte apoptosis. Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide endowed with a range of trophic effects in several cell types; including chondrocytes. However; its role in OA has not been studied. To address this issue, we investigated whether PACAP expression is affected in OA cartilage obtained from experimentally-induced OA rat models, and then studied the effects of PACAP in isolated chondrocytes exposed to IL-1β in vitro to mimic the inflammatory milieu of OA cartilage. OA induction was established by histomorphometric and histochemical analyses. Changes in PACAP distribution in cartilage, or its concentration in synovial fluid (SF), were assessed by immunohistochemistry and ELISA. Results showed that PACAP abundance in cartilage tissue and SF was high in healthy controls. OA induction decreased PACAP levels both in affected cartilage and SF. Invitro, PACAP prevented IL-1β-induced chondrocyte apoptosis, as determined by MTT assay; Hoechst staining and western blots of apoptotic-related proteins. These changes were also accompanied by decreased i-NOS and COX-2 levels, suggesting an anti-inflammatory effect. Altogether, these findings support a potential role for PACAP as a chondroprotective agent for the treatment of OA.

Impact of Histochemistry on biomedical research: looking through the articles published in a long-established histochemical journal

Histochemistry provides the unique opportunity to detect single molecules in the very place where they exert their structural roles or functional activities: this makes it possible to correlate structural organization and function, and may be fruitfully exploited in countless biomedical research topics. Aiming to estimate the impact of histochemical articles in the biomedical field, the last few years citations of articles published in a long-established histochemical journal have been considered. This brief survey suggests that histochemical journals, especially the ones open to a large spectrum of research subjects, do represent an irreplaceable source of information not only for cell biologists, microscopists or anatomists, but also for biochemists, molecular biologists and biotechnologists.

Biosynthesis of collagen I, II, RUNX2 and lubricin at different time points of chondrogenic differentiation in a 3D in vitro model of human mesenchymal stem cells derived from adipose tissue

The first aim of the study was to identify the most appropriate time for differentiation of adipose tissue derived mesenchymal stem cells (MSCs) to chondrocytes, through the self-assembly process. For this purpose, the expression of some chondrocyte markers, such as collagen type I, collagen type II, RUNX2 and lubricin was investigated at different times (7, 14, 21 and 28 days) of chondrogenic differentiation of MSCs, by using immunohistochemistry and Western blot analysis. The second aim of the study was to demonstrate that the expression of lubricin, such as the expression of collagen type II, could be a possible biomarker for the detection of chondrocytes well-being and viability in the natural self-assembling constructs, called 'cell pellets'. Histology (hematoxylin and eosin) and histochemistry (alcian blue staining) methods were used to assess the chondrogenic differentiation of MSCs. The results showed that after 21 days the differentiated chondrocytes, when compared with MSCs cultured without chondrogenic medium (CD44, CD90 and CD105 positive; CD45, CD14 and CD34 negative), were able to produce significant quantities of collagen type I, collagen type II, and lubricin, suggesting hyaline cartilage formation. During the differentiation phase, the cells showed a reduced expression of RUNX2, a protein expressed by osteoblasts. Our studies demonstrated that 21 days is the optimum time for the implantation of chondrocytes differentiated from adipose tissue-derived MSCs. This information could be useful for the future development of cell-based repair therapies for degenerative diseases of articular cartilage.

Expression of CHI3L1 and CHIT1 in osteoarthritic rat cartilage model. A morphological study

Osteoarthritis is a degenerative joint disease, which affects millions of people around the world. It occurs when the protective cartilage at the end of bones wears over time, leading to loss of flexibility of the joint, pain and stiffness. The cause of osteoarthritis is unknown, but its development is associated with different factors, such as metabolic, genetic, mechanical and inflammatory ones. In recent years the biological role of chitinases has been studied in relation to different inflammatory diseases and more in particular the elevated levels of human cartilage glycoprotein 39 (CHI3L1) and chitotriosidase (CHIT1) have been reported in a variety of diseases including chronic inflammation and degenerative disorders. The aim of this study was to investigate, by immunohistochemistry, the distribution of CHI3L1 and CHIT1 in osteoarthritic and normal rat articular cartilage, to discover their potential role in the development of this disease. The hypothesis was that the expression of chitinases could increase in OA disease. Immunohistochemical analysis showed that CHI3L1 and CHIT1 staining was very strong in osteoarthritic cartilage, especially in the superficial areas of the cartilage most exposed to mechanical load, while it was weak or absent in normal cartilage. These findings suggest that these two chitinases could be functionally associated with the development of osteoarthritis and could be used as markers, so in the future they could have a role in the daily clinical practice to stage the severity of the disease. However, the longer-term in vivoand in vitro studies are needed to understand the exact mechanism of these molecules, their receptors and activities on cartilage tissue.

Post-operative rehabilitation and nutrition in osteoarthritis

Osteoarthritis (OA) is a degenerative process involving the progressive loss of articular cartilage, synovial inflammation and structural changes in subchondral bone that lead to loss of synovial joint structural features and functionality of articular cartilage. OA represents one of the most common causes of physical disability in the world. Different OA treatments are usually considered in relation to the stage of the disease. In the early stages, it is possible to recommend physical activity programs that can maintain joint health and keep the patient mobile, as recommended by OA Research Society International (OARSI) and European League Against Rheumatism (EULAR). In the most severe and advanced cases of OA, surgical intervention is necessary. After, in early postoperative stages, it is essential to include a rehabilitation exercise program in order to restore the full function of the involved joint. Physical therapy is crucial for the success of any surgical procedure and can promote recovery of muscle strength, range of motion, coordinated walking, proprioception and mitigate joint pain. Furthermore, after discharge from the hospital, patients should continue the rehabilitation exercise program at home associated to an appropriate diet. In this review, we analyze manuscripts from the most recent literature and provide a balanced and comprehensive overview of the latest developments on the effect of physical exercise on postoperative rehabilitation in OA. The literature search was conducted using PubMed, Scopus, Web of Science and Google Scholar, using the keywords 'osteoarthritis', 'rehabilitation', 'exercise' and 'nutrition'. The available data suggest that physical exercise is an effective, economical and accessible to everyone practice, and it is one of the most important components of postoperative rehabilitation for OA.