The potential role of vascular endothelial growth factor (VEGF) in cartilage: how the angiogenic factor could be involved in the pathogenesis of osteoarthritis?

Osteoarthritis versus psoriasis arthritis: Physiopathology, cellular signaling, and therapeutic strategies

Osteoarthritis and psoriasis arthritis are two degenerative forms of arthritis that share similar yet also different manifestations at the histological, cellular, and clinical levels. Rheumatologists have marked them as two entirely distinct arthropathies. Given recent discoveries in disease initiation and progression, potential mechanisms, cellular signaling pathways, and ongoing clinical therapeutics, there are now more opportunities for discovering osteoarthritis drugs. This review summarized the osteoarthritis and psoriasis arthritis signaling pathways, crosstalk between BMP, WNT, TGF-β, VEGF, TLR, and FGF signaling pathways, biomarkers, and anatomical pathologies. Through bench research, we demonstrated that regenerative medicine is a promising alternative for treating osteoarthritis by highlighting significant scientific discoveries on entheses, multiple signaling blockers, and novel molecules such as immunoglobulin new antigen receptors targeted for potential drug evaluation. Furthermore, we offered valuable therapeutic approaches with a multidisciplinary strategy to treat patients with osteoarthritis or psoriasis arthritis in the coming future in the clinic.

Hypobaric hypoxia aggravates osteoarthritis via the alteration of the oxygen environment and bone remodeling in the subchondral zone

A high prevalence of osteoarthritis (OA) has been observed among individuals living at high altitudes, and hypobaric hypoxia (HH) can cause bone mass and strength deterioration. However, the effect of HH on OA remains unclear. In this study, we aimed to explore the impact of HH on OA and its potential mechanisms. A rat knee OA model was established by surgery, and the rats were bred in an HH chamber simulating a high-altitude environment. Micro-computed tomography (Micro-CT), histological analysis, and RNA sequencing were performed to evaluate the effects of HH on OA in vivo. A hypoxic co-culture model of osteoclasts and osteoblasts was also established to determine their effects on chondrogenesis in vitro. Cartilage degeneration significantly worsened in the HH-OA group compared to that in the normoxia-OA (N-OA) group, 4 weeks after surgery. Micro-CT analysis revealed more deteriorated bone mass in the HH-OA group than in the N-OA group. Decreased hypoxia levels in the cartilage and enhanced hypoxia levels in the subchondral bone were observed in the HH-OA group. Furthermore, chondrocytes cultured in a conditioned medium from the hypoxic co-culture model showed decreased anabolism and extracellular matrix compared to those in the normoxic model. RNA sequencing analysis of the subchondral bone indicated that the glycolytic signaling pathway was highly activated in the HH-OA group. HH-related OA progression was associated with alterations in the oxygen environment and bone remodeling in the subchondral zone, which provided new insights into the pathogenesis of OA.

The role of the complement system in disc degeneration and Modic changes

Disc degeneration and vertebral endplate bone marrow lesions called Modic changes are prevalent spinal pathologies found in chronic low back pain patients. Their pathomechanisms are complex and not fully understood. Recent studies have revealed that complement system proteins and interactors are dysregulated in disc degeneration and Modic changes. The complement system is part of the innate immune system and plays a critical role in tissue homeostasis. However, its dysregulation has also been associated with various pathological conditions such as rheumatoid arthritis and osteoarthritis. Here, we review the evidence for the involvement of the complement system in intervertebral disc degeneration and Modic changes. We found that only a handful of studies reported on complement factors in Modic changes and disc degeneration. Therefore, the level of evidence for the involvement of the complement system is currently low. Nevertheless, the complement system is tightly intertwined with processes known to occur during disc degeneration and Modic changes, such as increased cell death, autoantibody production, bacterial defense processes, neutrophil activation, and osteoclast formation, indicating a contribution of the complement system to these spinal pathologies. Based on these mechanisms, we propose a model how the complement system could contribute to the vicious cycle of tissue damage and chronic inflammation in disc degeneration and Modic changes. With this review, we aim to highlight a currently understudied but potentially important inflammatory pathomechanism of disc degeneration and Modic changes that may be a novel therapeutic target.

Nanoparticle-based inhibition of vascular endothelial growth factor receptors alleviates osteoarthritis pain and cartilage damage

Osteoarthritis (OA) is characterized by cartilage damage, inflammation, and pain. Vascular endothelial growth factor receptors (VEGFRs) have been associated with OA severity, suggesting that inhibitors targeting these receptors alleviate pain (via VEGFR1) or cartilage degeneration (via VEGFR2). We have developed a nanoparticle-based formulation of pazopanib (Votrient), an FDA-approved anticancer drug that targets both VEGFR1 and VEGFR2 (Nano-PAZII). We demonstrate that a single intraarticular injection of Nano-PAZII can effectively reduce joint pain for a prolonged time without substantial side effects in two different preclinical OA rodent models involving either surgical (upon partial medial meniscectomy) or nonsurgical induction (with monoiodoacetate). The injection of Nano-PAZII blocks VEGFR1 and relieves OA pain by suppressing sensory neuronal ingrowth into the knee synovium and neuronal plasticity in the dorsal root ganglia and spinal cord. Simultaneously, the inhibition of VEGFR2 reduces cartilage degeneration. These findings provide a mechanism-based disease-modifying drug strategy that addresses both pain symptoms and cartilage loss in OA.

Multifactorial Comparative Analysis of Platelet-Rich Plasma and Serum Prepared Using a Commercially Available Centrifugation Kit

Background Platelet-rich plasma (PRP) is an autologous product prepared by centrifuging whole blood. PRP is reported to have high tissue repair potential and anti-inflammatory properties. Recently, PRP has become a potential treatment option for osteoarthritis, contributing to pain relief and locomotive improvement. However, the underlying therapeutic mechanisms and key biochemical factors in PRP remain unclear. This study aimed to estimate the major factors for tissue repair involved in PRP treatment by comparing between serum and PRP prepared from the same patients using the Luminex assay. Methodology Blood samples were collected from nine healthy volunteers, and serum and PRP were prepared. PRP was prepared using a PEAK©︎ PRP SYSTEM kit of DePuy Synthes Mitek Sports Medicine (Raynham, Massachusetts, USA), which is a commercially available PRP preparation kit. The white blood cell count, hemoglobin level, and platelet count were automatically measured for both whole blood and PRP in the hospital's clinical laboratory using the XE-5000™ Automated Hematology System (Sysmex, Kobe, Japan). Comparative analysis of biological factors was then performed using the Luminex assay on serum and PRP. Results PRP was found to have significantly higher white blood cell and platelet counts and lower hemoglobin levels than whole blood. Furthermore, PRP contained significantly higher levels of various factors, including interleukin (IL)-1ra, IL-10, IL-13, C-C motif chemokine ligand (CCL)-2, CCL3, CCL4, CCL8, CCL13, CCL21, C-X-C motif chemokine ligand (CXCL)-10, matrix metalloproteinase (MMP)-3, MMP-9, cluster of differentiation (CD) 40 ligand, vascular endothelial growth factor (VEGF), VEGF-C, platelet-derived growth factor (PDGF)-AB, PDGF-BB, and bone morphogenic protein (BMP)-2. Additionally, IL-1ra and IL-4 showed significant correlations with white blood cell counts in PRP, whereas VEGF had a significant correlation with platelet counts. Conclusions PRP contains various factors in higher quantities than serum. Specifically, the notable increase in the anti-inflammatory cytokine IL-1ra is suggested to play a key role as a major therapeutic mechanism of PRP.

Endocan Knockdown Down-Regulates the Expression of Angiogenesis-Associated Genes in Il-1ß Activated Chondrocytes

Endocan is a small soluble proteoglycan (PG) known to be involved in inflammation and angiogenesis. Increased endocan expression was found in the synovia of arthritic patients and chondrocytes stimulated with IL-1ß. Considering these findings, we aimed to investigate the effects of endocan knockdown on the modulation of pro-angiogenic molecules expression in a model of IL-1ß-induced inflammation in human articular chondrocytes. Endocan, VEGF-A, MMP-9, MMP-13, and VEGFR-2 expression was measured in both normal and endocan knockdown chondrocytes stimulated with IL-1ß. VEGFR-2 and NF-kB activation were also measured. Results have shown that endocan, VEGF-A, VEGFR-2, MMP-9, and MMP-13 were significantly up-regulated during IL-1ß-induced inflammation; interestingly, the expression of such pro-angiogenic molecules and NF-kB activation were significantly reduced by endocan knockdown. These data support the hypothesis that endocan released by activated chondrocytes may be involved in the mechanisms that stimulate cell migration and invasion, as well as angiogenesis, in the pannus of arthritic joints.

Bevacizumab suppressed degenerative changes in articular cartilage explants from patients with osteoarthritis of the knee

BACKGROUND

This study was designed to test the hypothesis that blockade of vascular endothelial growth factor (VEGF) suppresses degenerative changes in articular cartilage from patients with osteoarthritis (OA).

METHODS

Articular cartilage from eight OA patients was subjected to explant culture for 2 days in the presence or absence of 10 ng/ml recombinant interleukin (IL)-1β. The blocking effect of VEGF was examined by the addition of 10 or 100 ng/ml of bevacizumab. The culture media were harvested, and markers for cartilage degradation were measured by sandwich enzyme-linked immunoassay. Total RNA was isolated from cartilage tissues, and gene expressions associated with the anabolic response were examined by the quantitative real-time polymerase chain reaction.

RESULTS

Bevacizumab significantly reduced concentrations of matrix metalloproteinase (MMP)-2, MMP-3, and cartilage oligomeric matrix protein in the culture media with and without IL-1β. Significant suppressive effects of bevacizumab on MMP-9 and MMP-13 were shown only in the presence of IL-1β. Gene expression of Col2a1 was significantly increased by the addition of bevacizumab in the absence of IL-1β.

CONCLUSION

Bevacizumab inhibits catabolic reactions and stimulates anabolic function in articular cartilage derived from OA patients directly, suggesting a protective effect on articular cartilage from OA progression.

In Vitro Study of the Therapeutic Potential of Brown Crude Fucoidans in Osteoarthritis Treatment

Osteoarthritis, one of the most common joint degenerative pathologies, still has no cure, and current treatments, such as nonsteroidal anti-inflammatory drugs, can cause serious adverse effects when taken for a long time. Brown seaweed crude fucoidans are used for the clinical treatment of several pathologies. In this study, the therapeutical potential of these biocompounds was analyzed in primary chondrocytes and the 260TT human chondrocyte cell line. Crude fucoidan from Undaria pinnatifida (Up) and Sargassum muticum (Sm) was obtained by different extraction techniques (microwave-assisted extraction, pressurized hot-water extraction, ultrasound-assisted extraction) and chemically and structurally characterized by Fourier transform infrared spectroscopy, high-performance size-exclusion chromatography, proton nuclear magnetic resonance, and scanning electron microscopy. Once cell viability was confirmed in chondrocytes treated with crude fucoidans, we evaluated their anti-inflammatory effects, observing a significant reduction in IL-6 production stimulated by IL-1β. Findings were confirmed by analysis of IL-6 and IL-8 gene expression, although only fucoidans from Up achieved a statistically significant reduction. Besides this, the antioxidant capacity of crude fucoidans was observed through the upregulation of Nrf-2 levels and the expression of its transcriptional target genes HO-1 and SOD-2, with compounds from Up again showing a more consistent effect. However, no evidence was found that crude fucoidans modulate senescence, as they failed to reduced β-galactosidase activity, cell proliferation, or IL-6 production in chondrocytes stimulated with etoposide. Thus, the findings of this research seem to indicate that the tested crude fucoidans are capable of partially alleviating OA-associated inflammation and oxidative stress, but fail to attenuate chondrocyte senescence.

Chondrocytes In Vitro Systems Allowing Study of OA

Osteoarthritis (OA) is an extremely complex disease, as it combines both biological-chemical and mechanical aspects, and it also involves the entire joint consisting of various types of tissues, including cartilage and bone. This paper describes the methods of conducting cell cultures aimed at searching for the mechanical causes of OA development, therapeutic solutions, and methods of preventing the disease. It presents the systems for the cultivation of cartilage cells depending on the level of their structural complexity, and taking into account the most common solutions aimed at recreating the most important factors contributing to the development of OA, that is mechanical loads. In-vitro systems used in tissue engineering to investigate the phenomena associated with OA were specified depending on the complexity and purposefulness of conducting cell cultures.

Emerging Targets for the Treatment of Osteoarthritis: New Investigational Methods to Identify Neo-Vessels as Possible Targets for Embolization

Osteoarthritis (OA) is the major cause of disability, affecting over 30 million US adults. Continued research into the role of neovascularization and inflammation related to osteoarthritis in large-animal models and human clinical trials is paramount. Recent literature on the pathogenetic model of OA has refocused on low-level inflammation, resulting in joint remodeling. As a result, this has redirected osteoarthritis research toward limiting or treating joint changes associated with persistent synovitis. The overall goal of this review is to better understand the cellular and tissue-specific mechanisms of inflammation in relation to a novel OA treatment modality, Genicular Artery Embolization (GAE). This article also assesses the utility and mechanism of periarticular neovascular embolization for the treatment of OA with a particular emphasis on the balance between pro-angiogenic and anti-angiogenic cytokines, inflammatory biomarkers, and imaging changes.

Mesenchymal Stem Cell Mechanisms of Action and Clinical Effects in Osteoarthritis: A Narrative Review

With the insufficient satisfaction rates and high cost of operative treatment for osteoarthritis (OA), alternatives have been sought. Furthermore, the inability of current medications to arrest disease progression has led to rapidly growing clinical research relating to mesenchymal stem cells (MSCs). The availability and function of MSCs vary according to tissue source. The three primary sources include the placenta, bone marrow, and adipose tissue, all of which offer excellent safety profiles. The primary mechanisms of action are trophic and immunomodulatory effects, which prevent the further degradation of joints. However, the function and degree to which benefits are observed vary significantly based on the exosomes secreted by MSCs. Paracrine and autocrine mechanisms prevent cell apoptosis and tissue fibrosis, initiate angiogenesis, and stimulate mitosis via growth factors. MSCs have even been shown to exhibit antimicrobial effects. Clinical results incorporating clinical scores and objective radiological imaging have been promising, but a lack of standardization in isolating MSCs prevents their incorporation in current guidelines.

Telomere length in patients with osteoarthritis: a systematic review and meta-analysis

BACKGROUND

Telomere length (TL) as a biomarker of aging was associated with many age-related diseases. The relationship between TL and osteoarthritis (OA), the most common form of joint diseases, had been investigated in a number of studies, but with the result inconsistent.

AIMS

The purpose of this study was to systematically evaluate the relationship between TL and OA.

METHODS

Until January 1, 2021, PubMed, Web of Science and Cochrane Library were comprehensively retrieved for relevant literatures. Quality of included literature was assessed using the Newcastle-Ottawa Scale (NOS) assessment scale. The pooled standard mean difference (SMD) with 95% confidence interval (CI) of Leukocytes TL was calculated using random-effect model. Subgroup analysis and meta-regression were used to investigate the potential source of heterogeneity.

RESULTS

Six original studies containing 678 OA patients and 1457 healthy controls were included in this meta-analysis. All six included studies were case-control designed. Pooled results showed that patients with OA had a shorter TL in peripheral blood leukocytes (PBLs) compared with healthy controls, (SMD = - 0.32, 95% CI - 0.57 to - 0.06, Z = - 2.45, P = 0.014). Subgroup and meta-regression analysis showed that sex ratio and body mass index (BMI) were possible sources of heterogeneity. Publication bias was not observed.

CONCLUSION

The TL of PBLs in patients with OA was shorter than that of healthy controls, suggesting that PBLs TL may be closely associated with the pathogenesis and progression of OA.

Overview of First-Line and Second-Line Pharmacotherapies for Osteoarthritis with Special Focus on Intra-Articular Treatment

Osteoarthritis (OA) can be defined as the result of pathological processes of various etiologies leading to damage to the articular structures. Although the mechanism of degenerative changes has become better understood due to the plethora of biochemical and genetic studies, the drug that could stop the degenerative cascade is still unknown. All available forms of OA therapy are based on symptomatic treatment. According to actual guidelines, comprehensive treatment of OA should always include a combination of various therapeutic options aimed at common goals, which are pain relief in the first place, and then the improvement of function. Local treatment has become more common practice, which takes place between rehabilitation and pharmacological treatment in the hierarchy of procedures. Only in the case of no improvement and the presence of advanced lesions visible in imaging tests, should surgery be considered. Currently, an increasing number of studies are being published suggesting that intra-articular injections may be as effective or even more effective than non-steroidal anti-inflammatory drugs (NSAIDs) and result in fewer systemic adverse events. The most commonly used preparations are hyaluronic acid (HA), glucocorticosteroids (GS), and also platelet-rich plasma (PRP) in recent years. This review aims to present the mechanism of action and clinical effectiveness of different pharmacological options in relieving pain and improving functions in OA as well as the emerging approach in intra-articular treatment with PRP.

Melatonin Promotes Antler Growth by Accelerating MT1-Mediated Mesenchymal Cell Differentiation and Inhibiting VEGF-Induced Degeneration of Chondrocytes

The sika deer is one type of seasonal breeding animal, and the growth of its antler is affected by light signals. Melatonin (MLT) is a neuroendocrine hormone synthesized by the pineal gland and plays an important role in controlling the circadian rhythm. Although the MLT/MT1 (melatonin 1A receptor) signal has been identified during antler development, its physiological function remains almost unknown. The role of MLT on antler growth in vivo and in vitro is discussed in this paper. In vivo, MLT implantation was found to significantly increase the weight of antlers. The relative growth rate of antlers showed a remarkable increased trend as well. In vitro, the experiment showed MLT accelerated antler mesenchymal cell differentiation. Further, results revealed that MLT regulated the expression of Collage type II (Col2a) through the MT1 binding mediated transcription of Yes-associated protein 1 (YAP1) in antler mesenchymal cells. In addition, treatment with vascular endothelial growth factor (VEGF) promoted chondrocytes degeneration by downregulating the expression of Col2a and Sox9 (SRY-Box Transcription Factor 9). MLT effectively inhibited VEGF-induced degeneration of antler chondrocytes by inhibiting the Signal transducers and activators of transcription 5/Interleukin-6 (STAT5/IL-6) pathway and activating the AKT/CREB (Cyclin AMP response-element binding protein) pathway dependent on Sox9 expression. Together, our results indicate that MLT plays a vital role in the development of antler cartilage.

Suppression of Osteoarthritis progression by post-natal Induction of Nkx3.2

Osteoarthritis (OA) is an incurable joint disease affecting 240 million elderly population, and major unmet medical needs exist for better therapeutic options for OA. During skeletal development, Nkx3.2 has been shown to promote chondrocyte differentiation and survival, but to suppress cartilage hypertrophy and blood vessel invasion. Here we show that Nkx3.2 plays a key role in osteoarthritis (OA) pathogenesis. Marked reduction of Nkx3.2 expression was observed in three different murine OA models. Consistent with these findings, analyses of surgery-induced and age-driven OA models revealed that cartilage-specific post-natal induction of Nkx3.2 can suppress OA progression in mice. These results suggest that Nkx3.2 may serve as a promising target for OA drug development.

Protein Levels and Microstructural Changes in Localized Regions of Early Cartilage Degeneration Compared with Adjacent Intact Cartilage

OBJECTIVE

It was hypothesized that the respective protein profiles of bovine cartilage from sites of localized mild to moderate (GI to GII) degeneration versus adjacent sites of intact tissue would vary in accordance with the tissue microstructural changes associated with a pre-osteoarthritic state.

METHODS

A total of 15 bovine patellae were obtained for this study. Paired samples of tissue were collected from the lateral region of each patella. If the patella contained a site of degeneration, a paired tissue set involved taking one sample each from the degenerated site and the intact tissue adjacent to it. Sufficient tissue was collected to facilitate 2 arms of investigation: microstructural imaging and proteome analysis. The microstructural analysis used a bespoke tissue preparation technique imaged with differential interference contrast optical microscopy to assess fibrillar scale destructuring and underlying bone spicule formation. An iTRAQ-based proteome analysis was performed using liquid chromatography-tandem mass spectrometry to identify the differential levels of proteins across the intact and degenerated cartilage and further, the results were validated with multiple reaction monitoring assay.

RESULTS

In the healthy cartilage pairs, there was no significant variation in protein profiles between 2 adjacent sample sites. In pairs of tissue that contained a sample of GI/GII tissue, there were both significant microstructural changes as well as the difference in abundance levels of 24 proteins.

CONCLUSIONS

From the known functions of the 24 proteins, found to be strongly aligned with the specific microstructural changes observed, a unique "proteins ensemble" involved in the initiation and progression of early cartilage degeneration is proposed.

The effect of maternal HMB supplementation on bone mechanical and geometrical properties, as well as histomorphometry and immunolocalization of VEGF, TIMP2, MMP13, BMP2 in the bone and cartilage tissue of the humerus of their newborn piglets

The presented experiment focuses on assessing the impact of HMB (hydroxy-β-methobutyrate) supplementation of mothers during pregnancy on the development of the skeletal system of their offspring. For this purpose, an experiment was carried out on 12 clinically healthy sows of the Great White Poland breed, which were divided randomly into two groups the control and the HMB group. All animals were kept under standard conditions and received the same feed for pregnant females. In contrast, females from the HMB group between 70 and 90 days were supplemented with 3-hydroxy-3-methylbutyle in the amount of 0.2g/kg b.w/day. Immediately after birth, the piglets were also divided into groups based on: sex, and presence or lack HMB supplementation, and subsequently were euthanized and humerus bones from all piglets were collected. Mother's HMB supplementation during pregnancy affected the multiple index of their offspring. The higher humerus mass and length was observed with the greater effect in males. Maternal supplementation also influenced on the geometrical and mechanical properties of the humerus as in the case of mass, this effect was higher in males. Also, the collagen structure of the compacted and trabecular bone changed under the HMB addition. Maternal supplementation also affected the expression of selected proteins in growth cartilage and trabecular bone. The obtained results show that the administration to the mother during pregnancy by the HMB significantly affects the development of the humerus in many ways. The obtained results also confirm the utility of such experiments in understanding of the importance of the pregnancy diet as an develop and adaptable factor of offspring organisms and are the base for further research in that area as well as in the protein markers expression area.

Alginate and its application to tissue engineering

Alginate is a polysaccharide of natural origin, which shows outstanding properties of biocompatibility, gel forming ability, non-toxicity, biodegradability and easy to process. Due to these excellent properties of alginate, sodium alginate, a hydrogel form of alginate, oxidized alginate and other alginate based materials are used in various biomedical fields, especially in drug delivery, wound healing and tissue engineering. Alginate can be easily processed as the 3D scaffolding materials which includes hydrogels, microcapsules, microspheres, foams, sponges, and fibers and these alginate based bio-polymeric materials have particularly used in tissue healing, healing of bone injuries, scars, wound, cartilage repair and treatment, new bone regeneration, scaffolds for the cell growth. Alginate can be easily modified and blended by adopting some physical and chemical processes and the new alginate derivative materials obtained have new different structures, functions, and properties having improved mechanical strength, cell affinity and property of gelation. This can be attained due to combination with other different biomaterials, chemical and physical crosslinking, and immobilization of definite ligands (sugar and peptide molecules). Hence alginate, its modified forms, derivative and composite materials are found to be more attractive towards tissue engineering. This article provides a comprehensive outline of properties, structural aspects, and application in tissue engineering.

Heparan sulfate functions are altered in the osteoarthritic cartilage

BACKGROUND

Heparan sulfate (HS) proteoglycans (PG) may be found at the chondrocyte surface and in the pericellular cartilage matrix, and are involved in cell-cell and cell-matrix interactions. An important function of HS chains is to regulate cell fate through specific interactions with heparin-binding proteins (HBP) modulated by their complex sulfation pattern. Osteoarthritis (OA) is a joint disorder characterized by the degradation of articular cartilaginous extracellular matrix. The aim of this study was to investigate HS structure and functions in osteoarthritic cartilages compared to normal cartilages (controls).

METHODS

Glycosaminoglycans (GAG) were extracted from human macroscopically normal cartilages (controls, n = 7) and (OA cartilages n = 11). HS were isolated and quantified using the DMMB quantification method. Their structure and functions were then compared using respectively a HPLC analysis and HBP binding tests and their phenotypic effects on murine chondrocytes were studied by RQ-PCR. Statistical analyzes were performed using a one-way ANOVA followed by a Dunnett's test or a t test for pairwise comparisons.

RESULTS

In OA, HS were characterized by increased sulfation levels compared to controls. Moreover, the capacity of these HS to bind HBP involved in the OA pathophysiological process such as FGF2 and VEGF was reduced. Chondroitin sulfates and keratan sulfates regulated these binding properties. Finally, HS from OA cartilages induced the mRNA levels of catabolic markers such as MMP3, MMP13, and TS4 and inhibited the mRNA levels of anabolic markers such as COL2, ACAN, SOX9, and VEGF in murine articular chondrocytes.

CONCLUSION

The sulfation of HS chains was increased in OA cartilages with changes in HBP binding properties and biological effects on chondrocyte phenotypes. Thus, modified HS present in altered cartilages could be a novel therapeutic target in OA.

The emerging landscape of nanotheranostic-based diagnosis and therapy for osteoarthritis

Osteoarthritis (OA) is a common degenerative disease involving numerous joint tissues and cells, with a growing rate in prevalence that ultimately results in a negative social impact. Early diagnosis, OA progression monitoring and effective treatment are of significant importance in halting OA process. However, traditional imaging techniques lack sensitivity and specificity, which lead to a delay in timely clinical intervention. Additionally, current treatments only slow the progression of OA but have not meet the largely medical need for disease-modifying therapy. In order to overcome the above-mentioned problems and improve clinical efficacy, nanotheranostics has been proposed on OA remedy, which has confirmed success in animal models. In this review, different imaging targets-based nanoprobe for early and timely OA diagnosis is first discussed. Second, therapeutic strategies delivered by nanosystem are summarized as much as possible. Their advantages and the potential for clinical translation are detailed discussed. Third, nanomedicine simultaneously combined with the imaging for OA treatment is introduced. Nanotheranostics dynamically tracked the OA treatment outcomes to timely and individually adjust therapy. Finally, future prospects and challenges of nanotechnology-based OA diagnosis, imaging and treatment are concluded and predicted. It is believed that nanoprobe and nanomedicine will become prospective in OA therapeutic revolution.

Human Chondrocyte Activation by Toxins From Premolis semirufa, an Amazon Rainforest Moth Caterpillar: Identifying an Osteoarthritis Signature

Pararamosis is a disease that occurs due to contact with the hairs of the larval stage of the Brazilian moth Premolis semirufa. Envenomation induces osteoarticular alterations with cartilage impairment that resembles joint synovitis. Thus, the toxic venom present in the caterpillar hairs interferes with the phenotype of the cells present in the joints, resulting in inflammation and promoting tissue injury. Therefore, to address the inflammatory mechanisms triggered by envenomation, we studied the effects of P. semirufa hair extract on human chondrocytes. We have selected for the investigation, cytokines, chemokines, matrix metalloproteinases (MMPs), complement components, eicosanoids, and extracellular matrix (ECM) components related to OA and RA. In addition, for measuring protein-coding mRNAs of some molecules associated with osteoarthritis (OA) and rheumatoid arthritis (RA), reverse transcription (RT) was performed followed by quantitative real-time PCR (RT-qPCR) and we performed the RNA-sequencing (RNA-seq) analysis of the chondrocytes transcriptome. In the supernatant of cell cultures treated with the extract, we observed increased IL-6, IL-8, MCP-1, prostaglandin E2, metalloproteinases (MMP-1, MMP-2, MMP-3 and MMP-13), and complement system components (C3, C4, and C5). We noticed a significant decrease in both aggrecan and type II collagen and an increase in HMGB1 protein in chondrocytes after extract treatment. RNA-seq analysis of the chondrocyte transcriptome allowed us to identify important pathways related to the inflammatory process of the disease, such as the inflammatory response, chemotaxis of immune cells and extracellular matrix (ECM) remodeling. Thus, these results suggest that components of Premolis semirufa hair have strong inflammatory potential and are able to induce cartilage degradation and ECM remodeling, promoting a disease with an osteoarthritis signature. Modulation of the signaling pathways that were identified as being involved in this pathology may be a promising approach to develop new therapeutic strategies for the control of pararamosis and other inflammatory joint diseases.

Endogenous cell recruitment strategy for articular cartilage regeneration

In the absence of timely and proper treatments, injuries to articular cartilage (AC) can lead to cartilage degeneration and ultimately result in osteoarthritis. Regenerative medicine and tissue engineering techniques are emerging as promising approaches for AC regeneration and repair. Although the use of cell-seeded scaffolds prior to implantation can regenerate and repair cartilage lesions to some extent, these approaches are still restricted by limited cell sources, excessive costs, risks of disease transmission and complex manufacturing practices. Recently developed acellular scaffold approaches that rely on the recruitment of endogenous cells to the injured sites avoid these drawbacks and offer great promise for in situ AC regeneration. Multiple endogenous stem/progenitor cells (ESPCs) are found in joint-resident niches and have the capability to migrate to sites of injury to participate in AC regeneration. However, the natural recruitment of ESPCs is insufficient, and the local microenvironment is hostile after injury. Hence, an endogenous cell recruitment strategy based on the combination of chemoattractants and acellular scaffolds to effectively and specifically recruit ESPCs and improve local microenvironment may provide new insights into in situ AC regeneration. This review provides a brief overview of: (1) the status of endogenous cell recruitment strategy; (2) the subpopulations, potential migration routes (PMRs) of joint-resident ESPCs and their immunomodulatory and reparative effects; (3) chemoattractants and their potential adverse effects; (4) scaffold-based drug delivery systems (SDDSs) that are utilized for in situ AC regeneration; and (5) the challenges and future perspectives of endogenous cell recruitment strategy for AC regeneration. STATEMENT OF SIGNIFICANCE: Although the endogenous cell recruitment strategy for articular cartilage (AC) regeneration has been investigated for several decades, much work remains to be performed in this field. Future studies should have the following aims: (1) reporting the up-to-date progress in the endogenous cell recruitment strategies; (2) determining the subpopulations of ESPCs, the cellular and molecular mechanisms underlying the migration of these cells and their anti-inflammatory, immunomodulatory and reparative effects; (3) elucidating the chemoattractants that enhance ESPC recruitment and their potential adverse effects; and (4) developing advanced SDDSs for chemoattractant dispatch. Herein, we present a systematic overview of the aforementioned issues to provide a better understanding of endogenous cell recruitment strategies for AC regeneration and repair.

Triiodothyronine potentiates angiogenesis-related factor expression through PI3K/AKT signaling pathway in human osteoarthritic osteoblasts

Objective(s):

Previous study has indicated that triiodothyronine (T3) facilitated cartilage degeneration in osteoarthritis (OA). This study aimed to investigate the effects of T3 on angiogenesis-related factor expression in human osteoblasts of OA subchondral bone.

Materials and Methods:

The subchondral bone specimens were obtained from OA patients and healthy participants. The expressions of VEGF, HIF-1α, AKT, and phosphorylated AKT was detected by immunohistochemistry, Western blotting, and RT-qPCR in OA. Angiogenesis-related factor expression in OA osteoblasts was measured by treating different concentrations of T3. The hypoxia model and PX-478 (HIF-1α inhibitor) were employed to confirm the regulative role of HIF-1α for VEGF expression. The level of VEGF secretion was examined in osteoblasts supernatant using ELISA.

Results:

Immunohistochemistry showed strong staining of VEGF and HIF-1α in OA subchondral bone. The expression of VEGF, HIF-1α, and p-AKT in OA osteoblasts was higher than that of normal osteoblasts at protein and mRNA levels. The physiological concentration of T3 (10-7 M) in OA osteoblasts up-regulated the expression of VEGF, HIF-1α, and p-AKT after 24 hr and 48 hr culture, while a higher dose of T3 displayed the adverse effects. Additionally, VEGF and p-AKT expression was down-regulated when PX-478 inhibited HIF-1α protein.

Conclusion:

Our results suggested that local T3 could effectively increase angiogenesis-related factor expression by PI3K/AKT signaling pathway, and HIF-1α regulated the VEGF expression in OA osteoblasts.

The role of macrophages in osteoarthritis and cartilage repair

Osteoarthritis (OA) is a family of degenerative diseases affecting multiple joint tissues. Despite the diverse etiology and pathogenesis of OA, increasing evidence suggests that macrophages can play a significant role in modulating joint inflammation, and thus OA severity, via various secreted mediators. Recent advances in next-generation sequencing technologies coupled with proteomic and epigenetic tools have greatly facilitated research to elucidate the embryonic origin of macrophages in various tissues including joint synovium. Furthermore, scientists have now begun to appreciate that macrophage polarization can span beyond the conventionally recognized binary states (i.e., pro-inflammatory M1-like vs anti-inflammatory M2-like) and may encompass a broad spectrum of phenotypes. Although the presence of these cells has been shown in multiple joint tissues, additional mechanistic studies are required to provide a comprehensive understanding of the precise role of these diverse macrophage populations in OA onset and progression. New approaches that can modulate macrophages into desired functional phenotypes may provide novel therapeutic strategies for preventing OA or enhancing cartilage repair and regeneration.

Inner histopathologic changes and disproportionate zone volumes in foetal growth plates following gestational hypoglycaemia in rats

Maternal hypoglycaemia throughout gestation until gestation day (GD)20 delays foetal growth and skeletal development. While partially prevented by return to normoglycaemia after completed organogenesis (GD17), underlying mechanisms are not fully understood. Here, we investigated the pathogenesis of these changes and significance of maternal hypoglycaemia extending beyond organogenesis in non-diabetic rats. Pregnant rats received insulin-infusion until GD20 or GD17, with sacrifice on GD20. Hypoglycaemia throughout gestation increased maternal corticosterone levels, which correlated with foetal levels. Growth plates displayed central histopathologic changes comprising disrupted cellular organisation, hypertrophic chondrocytes, and decreased cellular density; expression of pro-angiogenic factors, HIF-1α and VEGF-A increased in surrounding areas. Disproportionately decreased growth plate zone volumes and lower expression of the structural protein MATN-3 were seen, while bone ossification parameters were normal. Ending maternal/foetal hypoglycaemia on GD17 reduced incidence and severity of histopathologic changes and with normal growth plate volume. Compromised foetal skeletal development following maternal hypoglycaemia throughout gestation is hypothesised to result from corticosterone-induced hypoxia in growth plates, where hypoxia disrupts chondrocyte maturation and growth plate structure and volume, decreasing long bone growth. Maternal/foetal hypoglycaemia lasting only until GD17 attenuated these changes, suggesting a pivotal role of glucose in growth plate development.

Deciphering the Association of Cytokines, Chemokines, and Growth Factors in Chondrogenic Differentiation of Human Bone Marrow Mesenchymal Stem Cells Using an ex vivo Osteochondral Culture System

Osteoarthritis (OA) is a chronic degenerative joint disorder associated with degradation and decreased production of the extracellular matrix, eventually leading to cartilage destruction. Limited chondrocyte turnover, structural damage, and prevailing inflammatory milieu prevent efficient cartilage repair and restoration of joint function. In the present study, we evaluated the role of secreted cytokines, chemokines, and growth factors present in the culture supernatant obtained from an ex vivo osteochondral model of cartilage differentiation using cartilage pellets (CP), bone marrow stem cells (BM-MSCs), and/or BM-MSCs + CP. Multiplex cytokine analysis showed differential secretion of growth factors (G-CSF, GM-CSF, HGF, EGF, VEGF); chemokines (MCP-1, MIP1α, MIP1β, RANTES, Eotaxin, IP-10), pro-inflammatory cytokines (IL-1β, IL-2, IL-5, IL-6, IL-8, TNFα, IL-12, IL-15, IL-17) and anti-inflammatory cytokines (IL-4, IL-10, and IL-13) in the experimental groups compared to the control. In silico analyses of the role of stem cells and CP in relation to the expression of various molecules, canonical pathways and hierarchical cluster patterns were deduced using the Ingenuity Pathway Analysis (IPA) software (Qiagen, United States). The interactions of the cytokines, chemokines, and growth factors that are involved in the cartilage differentiation showed that stem cells, when used together with CP, bring about a favorable cell signaling that supports cartilage differentiation and additionally helps to attenuate inflammatory cytokines and further downstream disease-associated pro-inflammatory pathways. Hence, the autologous or allogeneic stem cells and local cartilage tissues may be used for efficient cartilage differentiation and the management of OA.

From skeletal development to the creation of pluripotent stem cell-derived bone-forming progenitors

Bone has many functions. It is responsible for protecting the underlying soft organs, it allows locomotion, houses the bone marrow and stores minerals such as calcium and phosphate. Upon damage, bone tissue can efficiently repair itself. However, healing is hampered if the defect exceeds a critical size and/or is in compromised conditions. The isolation or generation of bone-forming progenitors has applicability to skeletal repair and may be used in tissue engineering approaches. Traditionally, bone engineering uses osteochondrogenic stem cells, which are combined with scaffold materials and growth factors. Despite promising preclinical data, limited translation towards the clinic has been observed to date. There may be several reasons for this including the lack of robust cell populations with favourable proliferative and differentiation capacities. However, perhaps the most pertinent reason is the failure to produce an implant that can replicate the developmental programme that is observed during skeletal repair. Pluripotent stem cells (PSCs) can potentially offer a solution for bone tissue engineering by providing unlimited cell sources at various stages of differentiation. In this review, we summarize key embryonic signalling pathways in bone formation coupled with PSC differentiation strategies for the derivation of bone-forming progenitors.This article is part of the theme issue 'Designer human tissue: coming to a lab near you'.

Platelet-Rich Fibrin Scaffolds for Cartilage and Tendon Regenerative Medicine: From Bench to Bedside

Nowadays, research in Tissue Engineering and Regenerative Medicine is focusing on the identification of instructive scaffolds to address the requirements of both clinicians and patients to achieve prompt and adequate healing in case of injury. Among biomaterials, hemocomponents, and in particular Platelet-rich Fibrin matrices, have aroused widespread interest, acting as delivery platforms for growth factors, cytokines and immune/stem-like cells for immunomodulation; their autologous origin and ready availability are also noteworthy aspects, as safety- and cost-related factors and practical aspects make it possible to shorten surgical interventions. In fact, several authors have focused on the use of Platelet-rich Fibrin in cartilage and tendon tissue engineering, reporting an increasing number of in vitro, pre-clinical and clinical studies. This narrative review attempts to compare the relevant advances in the field, with particular reference being made to the regenerative role of platelet-derived growth factors, as well as the main pre-clinical and clinical research on Platelet-rich Fibrin in chondrogenesis and tenogenesis, thereby providing a basis for critical revision of the topic.

A Heparan Sulfate Device for the Regeneration of Osteochondral Defects

IMPACT STATEMENT

Repairing damaged joint cartilage remains a significant challenge. Treatment involving microfracture, tissue grafting, or cell therapy provides some benefit, but seldom regenerates lost articular cartilage. Providing a point-of-care solution that is cell and tissue free has the potential to transform orthopedic treatment for such cases. Glycosaminoglycans such as heparan sulfate (HS) are well suited for this purpose because they provide a matrix that enhances the prochondrogenic activities of growth factors normally found at sites of articular damage. In this study, we show the potential of a novel HS device, which is free of exogenous cells or growth factors, in regenerating osteochondral defects.

Transcriptome analyses identify key genes and potential mechanisms in a rat model of osteoarthritis

BACKGROUND

Osteoarthritis (OA) is one of the most common degenerative diseases of the joints worldwide, but still the pathogenesis of OA is largely unknown. The purpose of our study is to clarify key candidate genes and relevant signaling pathways in a surgical-induced OA rat model.

METHODS

The microarray raw data of GSE8077 was downloaded from GEO datasets. GeoDiver were employed to screen differentially-expressed genes (DEGs). Enrichment analyses of DEGs were performed using Metascape. Construction of protein-protein interaction (PPI) network and identification of key genes were conducted using STRING, Cytoscape v3.6.0, and Centiscape2.2. Furthermore, miRDB and Cytoscape v3.6.0 were used for visualization of miRNA-mRNA regulatory network. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis for predicted miRNAs was undertaken using DIANA-miRPath v3.0.

RESULTS

Several DEGs (188 in comparison between OA and sham-operated group and 160 in comparison between OA and contralateral group) were identified. DEGs mainly enriched in vasculature development, regulation of cell migration, response to growth factor (Gene ontology), and ECM-receptor interaction (KEGG). Two comparison cohorts shared 79 intersection genes, and of these, Ccl2, Col4a1, Col1a1, Aldh1a3, and Itga8 were defined as the hub genes. Predicted miRNAs of seven DEGs from sub-networks mainly enriched in MAPK signaling pathway.

CONCLUSION

The current study shows that some key genes and pathways, such as Ccl2, Col4a1, Col1a1, Aldh1a3, Itga8, ECM-receptor interaction, and MAPK signaling pathway may be associated with OA progression and act as potential biomarkers and therapeutic targets for OA.

VEGF-A is associated with early degenerative changes in cartilage and subchondral bone

Paired cartilage and subchondral bone of subjects with no clinical history of joint disorders were analyzed to determine whether antioxidant enzymes, inflammatory cytokines and growth factors can be linked to a pre-osteoarthritis. Tissue explants were phenotyped according to Osteoarthritis Research Society International grading and micro-computed tomography, and also screened for the expression of several markers using quantitative polymerase chain reaction. The expression of these same genes was measured in SW1353 cells treated with hydrogen peroxide, to gain insight into the pathways involved with oxidative stress responses. Vascular endothelial growth factor A (VEGF-A) was up-regulated in the cartilage samples that showed early cartilage or bone degeneration. Oxidative stress in chondrocytes provoked up-regulation of interleukin-1β, interleukin-6, aggrecan, and SRY-box containing gene 9. Our results confirm the hitherto evidence of the deteriorating effects of the oxidative stress on cartilage and suggest the link between VEGF-A and pre-osteoarthritis.

Role of ATP during the initiation of microvascularization: acceleration of an autocrine sensing mechanism facilitating chemotaxis by inorganic polyphosphate

The in vitro tube formation assay with human umbilical vein endothelial cells (HUVEC) was applied to identify the extra- and intracellular sources of metabolic energy/ATP required for cell migration during the initial stage of microvascularization. Extracellularly, the physiological energy-rich polymer, inorganic polyphosphate (polyP), applied as biomimetic amorphous calcium polyP microparticles (Ca-polyP-MP), is functioning as a substrate for ATP generation most likely via the combined action of the alkaline phosphatase (ALP) and the adenylate kinase (AK). The linear Ca-polyP-MP with a size of 40 phosphate units, close to the polyP in the acidocalcisomes in the blood platelets, were found to increase endothelial cell tube formation, as well as the intracellular ATP levels. Depletion of extracellular ATP with apyrase suppressed tube formation during the initial incubation period. Inhibition experiments revealed that inhibitors (levamisole and Ap5A) of the enzymes involved in extracellular ATP generation strongly reduce the Ca-polyP-MP-induced tube formation. The stimulatory effect of Ca-polyP-MP was also diminished by the glycolysis inhibitor oxamate and trifluoperazine which blocks endocytosis, as well as by MRS2211, an antagonist of the P2Y₁₃ receptor. Oligomycin, an inhibitor of the mitochondrial F₀F₁-ATP synthase, displayed no effect at lower concentrations on tube formation. Electron microscopic data revealed that after cellular uptake, the Ca-polyP-MP accumulate close to the cell membrane. We conclude that in HUVEC exposed to polyP, ATP is formed extracellularly via the coupled ALP-AK reaction, and intracellularly during glycolysis. The results suggest an autocrine signaling pathway of ATP with polyP as an extracellular store of metabolic energy for endothelial cell migration during the initial vascularization process.

Onset and Progression of Human Osteoarthritis-Can Growth Factors, Inflammatory Cytokines, or Differential miRNA Expression Concomitantly Induce Proliferation, ECM Degradation, and Inflammation in Articular Cartilage?

Osteoarthritis (OA) is a degenerative whole joint disease, for which no preventative or therapeutic biological interventions are available. This is likely due to the fact that OA pathogenesis includes several signaling pathways, whose interactions remain unclear, especially at disease onset. Early OA is characterized by three key events: a rarely considered early phase of proliferation of cartilage-resident cells, in contrast to well-established increased synthesis, and degradation of extracellular matrix components and inflammation, associated with OA progression. We focused on the question, which of these key events are regulated by growth factors, inflammatory cytokines, and/or miRNA abundance. Collectively, we elucidated a specific sequence of the OA key events that are described best as a very early phase of proliferation of human articular cartilage (AC) cells and concomitant anabolic/catabolic effects that are accompanied by incipient pro-inflammatory effects. Many of the reviewed factors appeared able to induce one or two key events. Only one factor, fibroblast growth factor 2 (FGF2), is capable of concomitantly inducing all key events. Moreover, AC cell proliferation cannot be induced and, in fact, is suppressed by inflammatory signaling, suggesting that inflammatory signaling cannot be the sole inductor of all early OA key events, especially at disease onset.

New insights into the natural course of knee osteoarthritis: early regulation of cytokines and growth factors, with emphasis on sex-dependent angiogenesis and tissue remodeling. A pilot study

OBJECTIVE

This study was conducted to identify cytokine profiles associated with radiographic phenotypes of knee osteoarthritis (rKOA) with a focus on early stage of the disease.

METHODS

The pilot population study involved 60 middle-aged patients (mean age 50 ± 7.3y.). Standardized weight-bearing anteroposterior and axial radiographs were used to assess rKOA severity in tibiofemoral (TFJ) of patellofemoral joint (PFJ) by grading system (grades 0-3). Luminex (xMAP^®) technology was used to simultaneously assess 60 biomarkers (BMs).

RESULTS

Several pathways of angiogenic (CXCL10/IP-10, FGF1/2, PDGF-AA/BB, ANG1, RANTES), tissue remodeling/fibrosis (MMP1/3, TIMP2/3/4, TGFβ), and fat tissue (leptin) BMs associated with rKOA severity already in very early phase (grade 1). We identified several sets of cytokines as key markers of early knee osteoarthritis (KOA) predicting radiographic features in logistic-regression models (AUC = 0.80-0.97). Marked sex-specificity of rKOA course was detected: upregulation of angiogenesis dominated in females, whereas the activation of tissue remodeling was dominant in males. Several of these shifts, e.g., decrease of CXCL10/IP-10, took place only in grade 1 KOA and disappeared or reversed in later stages. OA of different knee-joint compartments has distinct profiles of cytokines. A broad list of BMs (TIMP2/3/4, MMP1/3, TGFβ1/2, vWF-A2, sE-selectin and leptin) associated with OA in the PFJ.

CONCLUSION

Our results demonstrate that substantial and time-limited shifts in the angiogenic and TIMP/MMP systems occur in the early stage of KOA. Our study findings highlight the sex-, grade- and compartment-dependent shifts in above processes. The data may contribute to the individualized prevention of KOA in the future.

Gene expression of matrix metalloproteinase 9 (MMP9), matrix metalloproteinase 13 (MMP13), vascular endothelial growth factor (VEGF) and fibroblast growth factor 23 (FGF23) in femur and vertebra tissues of the hypovitaminosis D kyphotic pig model

The hypovitaminosis D kyphotic pig provides a reliable model to study the initiation of bone lesions caused by maternal vitamin D (D) deficiencies. Matrix metalloproteinases (MMP; specifically, MMP9 and MMP13) and vascular endothelial growth factor (VEGF) are important in endochondral ossification and are potentially regulated by D. Fibroblast growth factor 23 (FGF23) is interrelated with D homoeostasis and bone mineralisation. Relative mRNA expression of MMP9, MMP13, VEGF and FGF23 was measured in pig femur and vertebra. Sows (n 37) were fed diets with 0 (-D), 8·125 (+D) or 43·750 (++D) µg D3/kg throughout gestation and lactation. At weaning (3 weeks), pigs were fed diets with 0 (-D) or 7·0 (+D) µg D3/kg, each with 75 and 95 % (LCaP) or 150 and 120 % (HCaP) of the Ca and P requirements. Pigs at birth (n 27), 3 weeks (n 27) and after the nursery period (7 weeks; n 72) were euthanised for analysis. At 3 weeks, femur MMP9 expression of pigs produced by +D or ++D sows was reduced (P<0·05) to 0·5-fold and VEGF expression to 0·4-fold compared with pigs from -D sows. At 7 weeks, MMP9 expression was reduced (P<0·05) to 0·45-fold in femur and 0·58-fold in vertebra from pigs produced by +D or ++D sows compared with pigs from -D sows. Pig femur VEGF expression was reduced to 0·75-fold in pigs produced by ++D sows. MMP9 and VEGF mRNA expression offer potential markers for the initiation of bone lesions in the hypovitaminosis D kyphotic pig model.

Protective Effects of Peucedanum japonicum Extract against Osteoarthritis in an Animal Model Using a Combined Systems Approach for Compound-Target Prediction

Peucedanum japonicum Thunberg is an herbal medicine used to treat neuralgia, rheumatoid arthritis, and inflammatory-related diseases. However, its effects on osteoarthritis (OA) and its regulatory mechanisms have not been investigated by network analysis. Here, we investigated the pharmacological effects of Peucedanum japonicum extract (PJE) on OA, by combining in vivo effective verification and network pharmacology prediction. Rats in which OA was induced by monosodium iodoacetate (MIA) were treated with PJE (200 mg/kg), and histopathological parameters, weight bearing distribution and inflammatory factors in serum and joint tissue were measured after 28 days of treatment. Additionally, in silico network analysis was used to predict holistic OA regulatory mechanisms of PJE. The results showed that PJE exerted potential protective effects by recovering hind paw weight bearing distribution, alleviating histopathological features of cartilage and inhibiting inflammatory mediator levels in the OA rat model. Furthermore, network analysis identified caspase-3 (CASP3), caspase-7 (CASP7), and cytochrome P450 2D6 (CYP2D6) as potential target genes; in addition, the TNF (Tumor necrosis factor) signaling pathway was linked to OA therapeutic action. Our combined animal OA model and network analysis confirmed the therapeutic effects of PJE against OA and identified intracellular signaling pathways, active compounds and target genes linked to its therapeutic action.

Italian consensus conference on guidelines for conservative treatment on lower limb muscle injuries in athlete

Provide the state of the art concerning (1) biology and aetiology, (2) classification, (3) clinical assessment and (4) conservative treatment of lower limb muscle injuries (MI) in athletes. Seventy international experts with different medical backgrounds participated in the consensus conference. They discussed and approved a consensus composed of four sections which are presented in these documents. This paper represents a synthesis of the consensus conference, the following four sections are discussed: (i) The biology and aetiology of MIs. A definition of MI was formulated and some key points concerning physiology and pathogenesis of MIs were discussed. (ii) The MI classification. A classification of MIs was proposed. (iii) The MI clinical assessment, in which were discussed anamnesis, inspection and clinical examination and are provided the relative guidelines. (iv) The MI conservative treatment, in which are provided the guidelines for conservative treatment based on the severity of the lesion. Furthermore, instrumental therapy and pharmacological treatment were discussed. Knowledge of the aetiology and biology of MIs is an essential prerequisite in order to plan and conduct a rehabilitation plan. Another important aspect is the use of a rational MI classification on prognostic values. We propose a classification based on radiological investigations performed by ultrasonography and MRI strongly linked to prognostic factors. Furthermore, the consensus conference results will able to provide fundamental guidelines for diagnostic and rehabilitation practice, also considering instrumental therapy and pharmacological treatment of MI. Expert opinion, level IV.

Bioactivity and composition of a preserved connective tissue matrix derived from human placental tissue

There are a wide variety of extracellular matrices that can be used for regenerative purposes. Placental tissue-based matrices are quickly becoming an attractive option given the availability of the tissue source and the wide variety of bioactive molecules knows to exist in unprocessed placental tissues. As fresh placental tissues are seldom an option at the point of care, we examined both the composition and bioactivity of a commercially packaged flowable placental connective tissue matrix (FPTM) (BioECM^® , Skye Biologics, Inc.) that was preserved by the proprietary HydraTek^® process. The FPTM contained significant amounts of collagen and various growth factors such as bFGF, EGF, PDGF, KGF, and PIGF. In addition, it contained high levels of tissue inhibitors of metalloproteinases (TIMP-1 and 2) and molecules known to modulate the immune response including TGF-β and IL-4. In terms of its bioactivity, the FPTM displayed the ability (1) to suppress INF-γ secretion in activated T-cells nearly fourfold over control media, (2) to inhibit methicillin resistant Staphylococcus aureus (MRSA) and Staphylococcus saprophyticus proliferation, (3) to increase the migration of adipose-derived stem cells (ASCs) nearly threefold over control media and (4) to adhere to ASCs in culture. When ASCs were exposed to FPTM in culture, the cells maintained healthy morphology and showed no significant changes in the expression of five genes involved in tissue growth and repair as compared to culture in standard growth media. © 2018 The Authors Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2731-2740, 2018.

Nanocrystal-Polymer Particles: Extended Delivery Carriers for Osteoarthritis Treatment

An efficient treatment for osteoarthritis (OA) can benefit from the local release of a high therapeutic dose over an extended period of time. Such a treatment will minimize systemic side effects and avoid the inconvenience of frequent injections. To this aim, nanocrystal-polymer particles (NPPs) are developed by combining the advantages of nanotechnology and microparticles. Nanocrystals are produced by wet milling kartogenin (KGN), which is known to promote chondrogenesis and to foster chondroprotection. A fluorescent biodegradable polymer is synthesized for intravital particle tracking. Polymer microparticles with 320 nm embedded KGN nanocrystals (KGN-NPPs) show a high drug loading of 31.5% (w/w) and an extended drug release of 62% over 3 months. In vitro, these particles do not alter mitochondrial activity in cultured human OA synoviocytes. In vivo, KGN-NPPs demonstrate higher bioactivity than a KGN solution in a murine mechanistic OA model based on histological assessment (Osteoarthritis Research Society International score), epiphyseal thickness (microcomputed tomography), OA biomarkers (e.g., vascular endothelial growth factor, Adamts5), and prolonged intra-articular persistence (fluorescence analysis). This work provides proof-of-concept of a novel and innovative extended drug delivery system with the potential to treat human OA.

Self-assembled thermoresponsive nanostructures of hyaluronic acid conjugates for osteoarthritis therapy

Under pathological conditions, joints and skin are often affected by an imbalance in the breakdown and production of hyaluronic acid (HA). The unique biochemical and biomechanical properties provided by HA must be restored for the long-term lubrication and cushioning effects. To overcome the inconvenience of repeated injections and the rapid degradation of exogenous HA treatments, HA is conjugated to a thermosensitive polymer, enabling the spontaneous formation of nanoparticles (HA Nano) at body temperature. Three HA Nano preparations are tested for their injectability, sensitivity to enzymatic degradation and cytocompatibility. One of them is delivered via subcutaneous and intra-articular injections to healthy mice and tested in a murine osteoarthritis (OA) model. It is found to be biocompatible, to offer a prolonged residence time at the injection site, have the ability to protect cartilage, to reduce pro-inflammatory cytokines and to preserve epiphysis thickness. In this study, HA Nano spontaneously forms nanoparticles at body temperature in vivo and is a promising candidate for the next generation of the sustainable/long-lasting treatment of OA and potentially also dermatological conditions.

Osteoarthritis and the Complement Cascade

Accumulating evidence demonstrates that complement activation is involved in the pathogenesis of osteoarthritis (OA). However, the intimate complement regulation and cross talk with other signaling pathways in joint-associated tissues remain incompletely understood. Recent insights are summarized and discussed here, to put together a more comprehensive picture of complement involvement in OA pathogenesis. Complement is regulated by several catabolic and inflammatory mediators playing a key role in OA. It seems to be involved in many processes observed during OA development and progression, such as extracellular cartilage matrix (ECM) degradation, chondrocyte and synoviocyte inflammatory responses, cell lysis, synovitis, disbalanced bone remodeling, osteophyte formation, and stem cell recruitment, as well as cartilage angiogenesis. In reverse, complement can be activated by various ECM components and their cleavage products, which are released during OA-associated cartilage degradation. There are, however, some other cartilage ECM components that can inhibit complement, underlining the diverse effects of ECM on the complement activation. It is hypothesized that complement might also be directly activated by mechanical stress, thereby contributing to OA. The question arises whether keeping the complement activation in balance could represent a future therapeutic strategy in OA treatment and in the prevention of its progression.

Excess Maternal Thyroxine Alters the Proliferative Activity and Angiogenic Profile of Growth Cartilage of Rats at Birth and Weaning

Objective The aim of this study was to unravel the mechanisms by which thyroxine affects skeletal growth by evaluating proliferative activity and angiogenic profile of growth cartilage of neonatal and weanling rats. Methods Sixteen adult Wistar rats were equally divided into 2 groups: control and treated with thyroxine during pregnancy and lactation. The weight, measurement of plasma free T4 and thyroids, femurs' histomorphometric analysis, and proliferative activity and angiogenic profile by immunohistochemical or real-time reverse transcriptase-polymerase chain reaction in growth cartilage was performed. Data were analyzed using Student's t test. Results The free T4 was significantly higher in the treated rats. However, the height of the follicular epithelium of the thyroid in newborns was significantly lower in the treated group. The excess maternal thyroxine significantly reduced the body weight and length of the femur in the offspring but significantly increased the thickness of trabecular bone and changed the height of the zones of the growth plate. Furthermore, excess maternal thyroxine reduced cell proliferation and vascular endothelial growth factor (VEGF) expression in the growth cartilage of newborn and 20-day-old rats ( P < 0.05). There was also a reduction in the immunohistochemical expression of Tie2 in the cartilaginous epiphysis of the newborns and FLK-1 in the articular cartilage of 20-day-old rats. No significant difference was observed in Ang2 expression. Conclusions The excess maternal thyroxine during pregnancy and lactation reduced endochondral bone growth in the progeny and reduced the proliferation rate and VEGF, Flk-1, and Tie2 expression in the cartilage of growing rats without altering the mRNA expression of Ang1 and Ang2.

HMGB1-induced angiogenesis in perforated disc cells of human temporomandibular joint

High mobility group 1 protein (HMGB1), a highly conserved nuclear DNA‐binding protein and inflammatory mediator, has been recently found to be involved in angiogenesis. Our previous study has demonstrated the elevation of HMGB1 in the tissue of perforated disc of temporomandibular joint (TMJ). Here, we investigated a novel mediator of HMGB1 in regulating hypoxia‐inducible factor‐1α (HIF‐1α) and vascular endothelial growth factor (VEGF) to mediate angiogenesis in perforated disc cells of TMJ. HMGB1 increased the expression of HIF‐1α and VEGF in a dose‐ and time‐dependent manner in these cells. Moreover, immunofluorescence assay exhibits that the HIF‐1α were activated by HMGB1. In addition, HMGB1 activated extracellular signal‐related kinase 1/2 (Erk1/2), Jun N‐terminal kinase (JNK), but not P38 in these cells. Furthermore, both U0126 (ErK inhibitor) and SP600125 (JNK inhibitor) significantly suppressed the enhanced production of HIF‐1α and VEGF induced by HMGB1. Tube formation of human umbilical vein endothelial cells (HUVECs) was significantly increased by exposure to conditioned medium derived from HMGB1‐stimulated perforated disc cells, while attenuated with pre‐treatment of inhibitors for VEGF, HIF‐1α, Erk and JNK, individually. Therefore, abundance of HMGB1 mediates activation of HIF‐1α in disc cells via Erk and JNK pathway and then, initiates VEGF secretion, thereby leading to disc angiogenesis and accelerating degenerative change of the perforated disc.

TGFβ1 induces hypertrophic change and expression of angiogenic factors in human chondrocytes

The transforming growth factor β1 (TGFβ1) plays an important role in cartilage development. However, whether TGFβ1 stimulates chondrocyte proliferation and cartilage regeneration in osteoarthritis (OA) remains elusive, especially in the context of different treatment and tissue environments. In the present study, we investigated the role of TGFβ1 in human chondrocyte culture in vitro, focusing on the morphological change of chondrocytes and the expression of angiogenic factors upon TGFβ1 stimulation. We found increased expression of biomarkers indicating chondrocyte hypertrophy and the chondrocytes aggregated to form networks when they were treated with TGFβ1. DNA microarray analysis revealed significantly increased expression of genes related to blood vessel formation in TGFβ1 treatment group compared to control group. Matrigel assay further demonstrated that chondrocytes had the potential to form network-like structure. These results suggested that TGFβ1 induces the hypertrophic change of chondrocytes culture in vitro and induce expression of angiogenic biomarkers. Therefore, application of TGFβ1 for chondrocyte culture in practice should be considered prudentially and targeting TGFβ1 or relevant receptors to block the signaling pathway might be a strategy to prevent or alleviate progression of osteoarthritis.