Joint distraction attenuates osteoarthritis by reducing secondary inflammation, cartilage degeneration and subchondral bone aberrant change

Exercise following joint distraction inhibits muscle wasting and delays the progression of post-traumatic osteoarthritis in rabbits by activating PGC-1α in skeletal muscle

OBJECTIVE

Muscle wasting frequently occurs following joint trauma. Previous research has demonstrated that joint distraction in combination with treadmill exercise (TRE) can mitigate intra-articular inflammation and cartilage damage, consequently delaying the advancement of post-traumatic osteoarthritis (PTOA). However, the precise mechanism underlying this phenomenon remains unclear. Hence, the purpose of this study was to examine whether the mechanism by which TRE following joint distraction delays the progression of PTOA involves the activation of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), as well as its impact on muscle wasting.

METHODS

Quadriceps samples were collected from patients with osteoarthritis (OA) and normal patients with distal femoral fractures, and the expression of PGC-1α was measured. The hinged external fixator was implanted in the rabbit PTOA model. One week after surgery, a PGC-1α agonist or inhibitor was administered for 4 weeks prior to TRE. Western blot analysis was performed to detect the expression of PGC-1α and Muscle atrophy gene 1 (Atrogin-1). We employed the enzyme-linked immunosorbent assay (ELISA) technique to examine pro-inflammatory factors. Additionally, we utilized quantitative real-time polymerase chain reaction (qRT-PCR) to analyze genes associated with cartilage regeneration. Synovial inflammation and cartilage damage were evaluated through hematoxylin-eosin staining. Furthermore, we employed Masson's trichrome staining and Alcian blue staining to analyze cartilage damage.

RESULTS

The decreased expression of PGC-1α in skeletal muscle in patients with OA is correlated with the severity of OA. In the rabbit PTOA model, TRE following joint distraction inhibited the expressions of muscle wasting genes, including Atrogin-1 and muscle ring finger 1 (MuRF1), as well as inflammatory factors such as interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in skeletal muscle, potentially through the activation of PGC-1α. Concurrently, the production of IL-1β, IL-6, TNF-α, nitric oxide (NO), and malondialdehyde (MDA) in the synovial fluid was down-regulated, while the expression of type II collagen (Col2a1), Aggrecan (AGN), SRY-box 9 (SOX9) in the cartilage, and superoxide dismutase (SOD) in the synovial fluid was up-regulated. Additionally, histological staining results demonstrated that TRE after joint distraction reduced cartilage degeneration, leading to a significant decrease in OARSI scores.TRE following joint distraction could activate PGC-1α, inhibit Atrogin-1 expression in skeletal muscle, and reduce C-telopeptides of type II collagen (CTX-II) in the blood compared to joint distraction alone.

CONCLUSION

Following joint distraction, TRE might promote the activation of PGC-1α in skeletal muscle during PTOA progression to exert anti-inflammatory effects in skeletal muscle and joint cavity, thereby inhibiting muscle wasting and promoting cartilage regeneration, making it a potential therapeutic intervention for treating PTOA.

Causal relationship between sarcopenia with osteoarthritis and the mediating role of obesity: a univariate, multivariate, two-step Mendelian randomization study

BACKGROUND

Recent genetic evidence supports a causal role for sarcopenia in osteoarthritis, which may be mediated by the occurrence of obesity or changes in circulating inflammatory protein levels. Here, we leveraged publicly available genome-wide association study data to investigate the intrinsic causal relationship between sarcopenia, obesity, circulating inflammatory protein levels, and osteoarthritis.

METHODS

In this study, we used Mendelian randomization analyses to explore the causal relationship between sarcopenia phenotypes (Appendicular lean mass [ALM], Low hand-grip strength [LHG], and usual walking pace [UWP]) and osteoarthritis (Knee osteoarthritis [KOA], and Hip osteoarthritis [HOA]). Univariable Mendelian randomization (UVMR) analyses were performed using the inverse variance weighted (IVW) method, MR-Egger, weighted median method, simple mode, and weighted mode, with the IVW method being the primary analytical technique. Subsequently, the independent causal effects of sarcopenia phenotype on osteoarthritis were investigated using multivariate Mendelian randomization (MVMR) analysis. To further explore the mechanisms involved, obesity and circulating inflammatory proteins were introduced as the mediator variables, and a two-step Mendelian randomization analysis was used to explore the mediating effects of obesity and circulating inflammatory proteins between ALM and KOA as well as the mediating proportions.

RESULTS

UVMR analysis showed a causal relationship between ALM, LHG, UWP and KOA [(OR = 1.151, 95% CI: 1.087-1.218, P = 1.19 × 10-6, PFDR = 7.14 × 10-6) (OR = 1.215, 95% CI: 1.004-1.470; P = 0.046, PFDR = 0.055) (OR = 0.503, 95% CI: 0.292-0.867; P = 0.013, PFDR = 0.027)], and a causal relationship between ALM, UWP and HOA [(OR = 1.181, 95% CI: 1.103-1.265, P = 2.05 × 10-6, PFDR = 6.15 × 10-6) (OR = 0.438, 95% CI: 0.226-0.849, P = 0.014, PFDR = 0.022)]. In the MVMR analyses adjusting for confounders (body mass index, insomnia, sedentary behavior, and bone density), causal relationships were observed between ALM, LHG, UWP and KOA [(ALM: OR = 1.323, 95%CI: 1.224- 1.431, P = 2.07 × 10-12), (LHG: OR = 1.161, 95%CI: 1.044- 1.292, P = 0.006), (UWP: OR = 0.511, 95%CI: 0.290- 0.899, P = 0.020)], and between ALM and HOA (ALM: OR = 1.245, 95%CI: 1.149- 1.348, P = 7.65 × 10-8). In a two-step MR analysis, obesity was identified to play a potential mediating role in ALM and KOA (proportion mediated: 5.9%).

CONCLUSIONS

The results of this study suggest that decreased appendicular lean mass, grip strength, and walking speed increase the risk of KOA and decreased appendicular lean mass increases the risk of HOA in patients with sarcopenia in a European population. Obesity plays a mediator role in the occurrence of KOA due to appendicular lean body mass reduction.

Mechanical crosstalk between the intervertebral disc, facet joints, and vertebral endplate following acute disc injury in a rabbit model

Background

Vertebral endplate sclerosis and facet osteoarthritis have been documented in animals and humans. However, it is unclear how these adjacent pathologies engage in crosstalk with the intervertebral disc. This study sought to elucidate this crosstalk by assessing each compartment individually in response to acute disc injury.

Methods

Eleven New Zealand White rabbits underwent annular disc puncture using a 16G or 21G needle. At 4 and 10 weeks, individual compartments of the motion segment were analyzed. Discs underwent T 1 relaxation mapping with MRI contrast agent gadodiamide as well T 2 mapping. Both discs and facets underwent mechanical testing via vertebra-disc-vertebra tension-compression creep testing and indentation testing, respectively. Endplate bone density was quantified via μCT. Discs and facets were sectioned and stained for histology scoring.

Results

Intervertebral discs became more degenerative with increasing needle diameter and time post-puncture. Bone density also increased in endplates adjacent to both 21G and 16G punctured discs leading to reduced gadodiamide transport at 10 weeks. The facet joints, however, did not follow this same trend. Facets adjacent to 16G punctured discs were less degenerative than facets adjacent to 21G punctured discs at 10 weeks. 16G facets were more degenerative at 4 weeks than at 10, suggesting the cartilage had recovered. The formation of severe disc osteophytes in 16G punctured discs between 4 and 10 weeks likely offloaded the facet cartilage, leading to the recovery observed.

Conclusions

Overall, this study supports that degeneration spans the whole spinal motion segment following disc injury. Vertebral endplate thickening occurred in response to disc injury, which limited the diffusion of small molecules into the disc. This work also suggests that altered disc mechanics can induce facet degeneration, and that extreme bony remodeling adjacent to the disc may promote facet cartilage recovery through offloading of the articular cartilage.

Harnessing joint distraction for the treatment of osteoarthritis: a bibliometric and visualized analysis

Osteoarthritis (OA) stands as a prevalent degenerative joint ailment, demanding immediate attention towards the development of efficacious therapeutic interventions. Presently, a definitive cure for OA remains elusive, and when conservative treatment modalities prove ineffective, resorting to a joint prosthesis becomes imperative. Temporary distraction emerges as a pivotal joint-preserving intervention in human OA patients, conferring both clinical amelioration and structural enhancements. Although extant clinical investigations exist, they are characterized by relatively modest sample sizes. Nonetheless, these studies furnish compelling evidence affirming that joint distraction engenders sustained clinical amelioration and structural refinement. Despite substantial strides in the last decade, a bibliometric analysis of joint distraction within the realm of osteoarthritis treatment research has been conspicuously absent. In this context, we have undertaken a comparative investigation utilizing bibliometric methodologies to scrutinize the landscape of joint distraction within osteoarthritis treatment. Our comprehensive analysis encompassed 469 scholarly articles. Our findings evince a consistent escalation in global research interest and publication output pertaining to this subject. The United States emerged as the frontrunner in international collaboration, publication count, and citation frequency, underscoring its preeminence in this domain. The journal "Osteoarthritis and Cartilage" emerged as the principal platform for disseminating research output on this subject. Notably, Mastbergen SC emerged as the most prolific contributor in terms of authorship. The identified keywords predominantly revolved around non-surgical interventions and joint arthroscopy procedures. This bibliometric analysis, augmented by visual representations, furnishes invaluable insights into the evolutionary trajectory of joint distraction as an osteoarthritis treatment modality spanning from 2003 to 2023. These insights will serve as a compass for the scientific community, facilitating further exploration in this promising domain.

Ankle joint distraction is a promising alternative treatment for patients with severe haemophilic ankle arthropathy

INTRODUCTION

Haemophilic ankle arthropathy (HAA) causes major morbidity. When conservative treatment fails, major surgical interventions are indicated. An alternative treatment to maintain joint mobility and postpone these interventions is desired.

AIM

To gather prospective data on clinical/structural changes after ankle joint distraction (AJD) in HAA.

METHODS

This study includes patients with severe HAA insufficiently responding to conservative treatment. AJD was performed during 8-10 weeks by use of an external frame. Questionnaires, physical examination and radiology were used to evaluate pain, function and structural changes before and 6, 12, 24 and 36 months after distraction. Mixed effect models were used for analysis.

RESULTS

This study includes eight cases (21-53 years). The fixed effects estimates of the visual analogue score (0-10) improved from 7.5 at baseline to 3.4 (p = .023) 3 years after distraction. The Haemophilia Activities List (HAL, 0-100) for basic/complex lower extremities functions improved from respectively 29.6 and 31.5 to 54.3 (p = .015) and 50.7 (p = .031). Joint mobility was maintained. Magnetic resonance imaging (MRI) showed thickened cartilage and reduced bone marrow oedema and subchondral cysts. Pin tract infections (n = 6) were effectively treated and no adverse bleeding events occurred. At 3-year follow-up, in none of the patients the originally indicated arthrodesis was performed.

CONCLUSION

This first prospective study showed that AJD in HAA results in decreased pain, improved function and decreased arthropathy-related MRI findings in the majority of patients for prolonged time. Although the study population is small and follow-up is relatively short, AJD may be promising to postpone invalidating interventions and might be a breakthrough treatment.

The catabolic-to-anabolic shift seen in the canine osteoarthritic cartilage treated with knee joint distraction occurs after the distraction period

Background

Methods

Results

Conclusion

The Translational Potential of this Article

Enhancing cartilage repair with optimized supramolecular hydrogel-based scaffold and pulsed electromagnetic field

Functional tissue engineering strategies provide innovative approach for the repair and regeneration of damaged cartilage. Hydrogel is widely used because it could provide rapid defect filling and proper structure support, and is biocompatible for cell aggregation and matrix deposition. Efforts have been made to seek suitable scaffolds for cartilage tissue engineering. Here Alg-DA/Ac-β-CD/gelatin hydrogel was designed with the features of physical and chemical multiple crosslinking and self-healing properties. Gelation time, swelling ratio, biodegradability and biocompatibility of the hydrogels were systematically characterized, and the injectable self-healing adhesive hydrogel were demonstrated to exhibit ideal properties for cartilage repair. Furthermore, the new hydrogel design introduces a pre-gel state before photo-crosslinking, where increased viscosity and decreased fluidity allow the gel to remain in a semi-solid condition. This granted multiple administration routes to the hydrogels, which brings hydrogels the ability to adapt to complex clinical situations. Pulsed electromagnetic fields (PEMF) have been recognized as a promising solution to various health problems owing to their noninvasive properties and therapeutic potentials. PEMF treatment offers a better clinical outcome with fewer, if any, side effects, and wildly used in musculoskeletal tissue repair. Thereby we propose PEMF as an effective biophysical stimulation to be 4th key element in cartilage tissue engineering. In this study, the as-prepared Alg-DA/Ac-β-CD/gelatin hydrogels were utilized in the rat osteochondral defect model, and the potential application of PEMF in cartilage tissue engineering were investigated. PEMF treatment were proven to enhance the quality of engineered chondrogenic constructs in vitro, and facilitate chondrogenesis and cartilage repair in vivo. All of the results suggested that with the injectable self-healing adhesive hydrogel and PEMF treatment, this newly proposed tissue engineering strategy revealed superior clinical potential for cartilage defect treatment.

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The supramolecular Alg-DA/Ac-β-CD/gelatin hydrogel with physical and chemical multiple crosslinking was fabricated.

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The multi-crosslinked structure of the hydrogels endows strong injection, adhesion abilities and mechanical performance.

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A pre-gel state of the hydrogel grants it more administration routes and ability to adapt to complex clinical scenarios.

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Pulsed electromagnetic field (PEMF) serves as the 4^th element in mesenchymal stem cell-based cartilage tissue engineering.

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Bioinformatics analysis reveal that PEMF regulates chondrogenesis and cell hypertrophy via ERK and p38 MAPK pathways.

Arthroscopic cartilage regeneration facilitating procedure: A decompressing arthroplasty for knee osteoarthritis

The effectiveness of arthroscopic treatment for knee osteoarthritis (OA) has always been a subject of debate. This study presents an innovative concept for the arthroscopic management of knee OA and investigates its clinical outcomes. An arthroscopic cartilage regeneration facilitating procedure (ACRFP) was performed on 693 knees of 411 patients with knee OA, with a mean age of 60 years (34-90 years), to eliminate the medial abrasion phenomenon (MAP) and decompress the patellofemoral joints. The Knee Society Score (KSS) and Knee Injury and Osteoarthritis Outcome Score (KOOS) were used to determine the subjective outcome. Roentgenographic changes in all cases and magnetic resonance imaging (MRI) variations in 20 randomly selected cases were evaluated for objective outcomes. We evaluated 634 knees in 369 patients (93.7%) with more than 3 years of follow-up (mean, 40 months; SD, 9) and found that the overall subjective satisfaction rate was 91.1%. Scores for KSS and all KOOS subscales improved statistically. Reversal of cartilage degeneration was observed in 80.1% of the entire series (radiographic outcome study) and 72.2% of the 18 randomly selected cases (1-year MRI outcome study). We found significant association between gender and OA severity, with regards to the subjective outcomes. Age, body mass index, pre-operative hyaluronic acid injection, OA severity, and type and severity of the medial plica were found to be important predictors of radiographic outcomes. An analysis of failed cases reaffirmed the need for early ACRFP and skilled post-operative care. ACRFP is an effective treatment for knee OA. It can benefit most patients and modify their degeneration processes if performed in time. However, further investigations are needed to confirm our concept of treatment.

Intermittent Hydrostatic Pressure Promotes Cartilage Repair in an Inflammatory Environment through Hippo-YAP Signaling In Vitro and In Vivo

The study of chondrogenic progenitor cells (CPCs) as seed cells has become a new focus of cartilage regeneration. The inflammatory environment of osteoarthritis (OA) inhibits the repair ability of CPCs. But the OA patients' CPCs showed an excellent regeneration ability with intermittent hydrostatic pressure (IHP). However, the mechanism is unclear. We compared the expression of the Hippo signaling effect factor YAP between OA and normal cartilages. Then, the relationship between the Kellgren-Lawrence (K-L) score of OA and the rate of YAP-positive cells was analyzed. The changes of CPCs after IHP and IL-1β applications were observed. The OA model was established by cutting the anterior cruciate ligament of rats. The knee joint of the OA rats was distracted by hinged external fixator to create suitable IHP, named as the IHP group. The IHP group plus intra-articular injection of Verteporfin (VP) was named as the IHP+VP group, and the untreated rat group was named as the CON group. Four and 8 weeks after the operation, the reparative effect was evaluated by MASSON staining and immunohistochemical staining. Lower levels of YAP1 and higher expressions of p-YAP1 were found in the OA group as compared to the normal group. IHP inhibited the Hippo signaling in an inflammatory environment and promoted the proliferation of CPCs. The cartilage deterioration in the CON group progressed more significantly than that in the IHP+VP group. The best reparative effect was observed in the IHP group with increased expression of YAP1 and decreased p-YAP1. These results hint that mechanical stress can activate CPCs and promote cartilage repair in an inflammatory environment through inhibiting Hippo signaling.

Mechanical traction from different knee joint angles in patients with knee osteoarthritis: A randomized controlled trial

OBJECTIVE

To compare the effect of mechanical traction from different knee angles on pain, physical function, and range of motion in patients with knee osteoarthritis.

DESIGN

A single-blinded, randomized controlled trial.

SETTING

Outpatient public and governmental Hospital clinics.

PARTICIPANTS

One hundred and twenty patients with knee osteoarthritis were randomly assigned into 4 equal groups with 30 patients in each group.

INTERVENTIONS

Group (A) received conventional physiotherapy(CPT) treatment; group (B) received CPT with knee traction from full extension, group (C) received CPT with knee traction from 90° flexion, while group (D) received CPT with knee traction from 20° flexion. Interventions were applied 3 sessions a week for 4 weeks.

OUTCOME MEASUREMENTS

Visual analog scale (VAS), knee passive range of motion and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were measured at baseline, immediately after 4 weeks of intervention, and after 4 weeks of no intervention as a follow-up.

RESULTS

After eight weeks, the mean (SD) for VAS scores were 30.97 ± 8.68, 24.0 ± 8.8, 15.43 ± 6.31, and 16.17 ± 6.11 mm; for total WOMAC scores were 26.77 ± 9.19, 20.3 ± 8.52, 13.27 ± 6.25, and 13.43 ± 7.14 for groups A, B, C and D, respectively. The three traction groups showed statistically significant changes in pain scores, physical function, and total WOMAC, but not for knee passive range of motion, in favor of traction groups C and D than the conventional group (P < 0.05).

CONCLUSIONS

Traction from 90°and 20° of knee flexion was found superior to full extension knee in improving pain and physical function, but not for knee passive range of motion, in patients with knee osteoarthritis.

Joint distraction for osteoarthritis: clinical evidence and molecular mechanisms

Joint distraction, the prolonged mechanical separation of the bones at a joint, has emerged as a joint-preserving treatment for end-stage osteoarthritis, with the gradually growing promise of implementation in regular clinical practice. Joint distraction of the knee has been most extensively studied, with these studies showing prolonged symptomatic improvement in combination with repair of cartilage tissue in degenerated knee joints, supporting the concept that cartilage repair can translate into real clinical benefit. The reversal of tissue degeneration observed with joint distraction could be the result of one or a combination of various proposed mechanisms, including partial unloading, synovial fluid pressure oscillation, mechanical and biochemical changes in subchondral bone, adhesion and chondrogenic commitment of joint-derived mesenchymal stem cells or a change in the molecular milieu of the joint. The overall picture that emerges from the combined evidence is relevant for future research and treatment-related improvements of joint distraction and for translation of the insights gained about tissue repair to other joint-preserving techniques. It remains to be elucidated whether optimizing the biomechanical conditions during joint distraction can actually cure osteoarthritis rather than only providing temporary symptomatic relief, but even temporary relief might be relevant for society and patients, as it will delay joint replacement with a prosthesis at an early age and thereby avert revision surgery later in life. Most importantly, improved insights into the underlying mechanisms of joint repair might provide new leads for more targeted treatment options.

Enhanced Extracellular Matrix Breakdown Characterizes the Early Distraction Phase of Canine Knee Joint Distraction

OBJECTIVE

Joint distraction triggers intrinsic cartilage repair in animal models of osteoarthritis (OA), corroborating observations in human OA patients treated with joint distraction. The present study explores the still largely elusive mechanism initiating this repair process.

DESIGN

Unilateral OA was induced in the knee joint of 8 dogs using the groove model; the contralateral joint served as a control. After 10 weeks, 4 animals received joint distraction, the other 4 serving as OA controls. Halfway the distraction period (after 4 weeks of a standard 8-week distraction treatment), all animals were euthanized, and joint tissues were collected. A targeted quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis was performed of commonly involved processes including matrix catabolism/anabolism, inflammation, and known signaling pathways in OA. In addition, cartilage changes were determined on tissue sections using the canine OARSI (Osteoarthritis Research Society International) histopathology score and collagen type II (COL2A1) immunostaining.

RESULTS

Midway distraction, the distracted OA joint showed an upregulation of proteolytic genes, for example, ADAMTS5, MMP9, MMP13, compared to OA alone and the healthy joints, which correlated with an increased OARSI score. Additionally, genes of the transforming growth factor (TGF)-β and Notch pathway, and markers associated with progenitor cells were increased.

CONCLUSIONS

Joint distraction initiates both catabolic and anabolic transcriptional responses. The enhanced turnover, and thereby renewal of the matrix, could be the key to the cartilage repair observed in the months after joint distraction.

Subchondral Bone Microarchitectural and Mineral Properties and Expression of Key Degradative Proteinases by Chondrocytes in Human Hip Osteoarthritis

Background: The purpose of this study was to investigate the relationship between the expression of key degradative enzymes by chondrocytes and the microarchitectural and mineral properties of subchondral bone across different stages of cartilage degradation in human hip osteoarthritis (OA). Methods: Osteochondral samples at different stages of cartilage degradation were collected from 16 femoral heads with OA. Osteochondral samples with normal cartilage were collected from seven femoral heads with osteoporosis. Microcomputed tomography was used for the investigation of subchondral bone microarchitecture and mineral densities. Immunohistochemistry was used to study the expression and distribution of MMP13 and ADAMTS4 in cartilage. Results: The microarchitecture and mineral properties of the subchondral plate and trabecular bone in OA varied with the severity of the degradation of the overlying cartilage. Chondrocytes expressing MMP13 and ADAMTS4 are mainly located in the upper zone(s) of cartilage regardless of the histopathological grades. The zonal expression of these enzymes in OA (i.e., the percentage of positive cells in the superficial, middle, and deep zones), rather than their overall expression (the percentage of positive cells in the full thickness of the cartilage), exhibited significant variation in relation to the severity of cartilage degradation. The associations between the subchondral bone properties and zonal and overall expression of these enzymes in the cartilage were generally weak or nonsignificant. Conclusions: Phenotypic changes in chondrocytes and remodelling of subchondral bone proceed at different rates throughout the process of cartilage degradation. Biological influences are more important for cartilage degradation at early stages, while biomechanical damage to the compromised tissue may outrun the phenotypic change of chondrocytes and is critical in the advanced stages.

Reproducing the Biomechanical Environment of the Chondrocyte for Cartilage Tissue Engineering

It is well known that the biomechanical and tribological performance of articular cartilage is inextricably linked to its extracellular matrix (ECM) structure and zonal heterogeneity. Furthermore, it is understood that the presence of native ECM components, such as collagen II and aggrecan, promote healthy homeostasis in the resident chondrocytes. What is less frequently discussed is how chondrocyte metabolism is related to the extracellular mechanical environment, at both the macro and microscale. The chondrocyte is in immediate contact with the pericellular matrix of the chondron, which acts as a mechanocoupler, transmitting external applied loads from the ECM to the chondrocyte. Therefore, components of the pericellular matrix also play essential roles in chondrocyte mechanotransduction and metabolism. Recreating the biomechanical environment through tuning material properties of a scaffold and/or the use of external cyclic loading can induce biosynthetic responses in chondrocytes. Decellularized scaffolds, which retain the native tissue macro- and microstructure also represent an effective means of recapitulating such an environment. The use of such techniques in tissue engineering applications can ensure the regeneration of skeletally mature articular cartilage with appropriate biomechanical and tribological properties to restore joint function. Despite the pivotal role in graft maturation and performance, biomechanical and tribological properties of such interventions is often underrepresented. This review outlines the role of biomechanics in relation to native cartilage performance and chondrocyte metabolism, and how application of this theory can enhance the future development and successful translation of biomechanically relevant tissue engineering interventions. Impact statement Physiological cartilage function is a key criterion in the success of a cartilage tissue engineering solution. The in situ performance is dependent on the initial scaffold design as well as extracellular matrix deposition by endogenous or exogenous cells. Both biological and biomechanical stimuli serve as key regulators of cartilage homeostasis and maturation of the resulting tissue-engineered graft. An improved understanding of the influence of biomechanics on cellular function and consideration of the final biomechanical and tribological performance will help in the successful development and translation of tissue-engineered grafts to restore natural joint function postcartilage trauma or osteoarthritic degeneration, delaying the requirement for prosthetic intervention.

MicroRNA-200b relieves LPS-induced inflammatory injury by targeting FUT4 in knee articular chondrocytes in vitro

Osteoarthritis (OA), characterized by the degeneration of articular cartilage, is a major problem in aging populations, and cartilage chondrocytes have been indicated to serve a curial role in the progression of OA. MicroRNA-200b-3p (miR-200b) was preliminarily identified to participate in OA. However, its role and mechanism of action in injured chondrocytes in OA remain unclear to date. In the present study, lipopolysaccharide (LPS)-treated cells isolated from normal knee articular cartilage were used to mimic inflammatory injury of OA chondrocytes. Cell viability, apoptosis and inflammatory responses were detected using Cell Counting Kit-8, flow cytometry and enzyme-linked immunosorbent assay, respectively. The expression levels of miR-200b and fucosyltransferase-4 (FUT4) were measured by reverse transcription-quantitative PCR and western blotting. The association between miR-200b and FUT4 was verified using TargetScan software, dual-luciferase reporter assay and RNA immunoprecipitation. The results indicated that LPS treatment decreased cell viability of primary chondrocytes, and increased apoptosis rate and production of IL-1β, IL-6 and TNF-α. The expression level of miR-200b was downregulated, and that of FUT4 was upregulated in OA cartilage tissues and LPS-treated normal chondrocytes compared with normal cartilage tissues and chondrocytes. Overexpression of miR-200b via transfection with miR-200b mimic inhibited the apoptosis rate and reduced the levels of IL-1β, IL-6 and TNF-α in LPS-stimulated chondrocytes. However, the suppressive effect of miR-200b overexpression on the LPS-induced inflammatory injury in chondrocytes was reversed by the restoration of FUT4 levels. Notably, FUT4 was indicated to be a downstream target of miR-200b and was negatively regulated by miR-200b. Taken together, the results of the current study indicated that miR-200b protected chondrocytes from LPS-induced inflammatory injury in vitro by targeting FUT4. These findings revealed the miR-200b/FUT4 axis as a potential candidate to target the degeneration of cartilages, thereby inhibiting the progression of OA.

Gene Expression Signatures of Synovial Fluid Multipotent Stromal Cells in Advanced Knee Osteoarthritis and Following Knee Joint Distraction

Osteoarthritis (OA) is the most common musculoskeletal disorder. Although joint replacement remains the standard of care for knee OA patients, knee joint distraction (KJD), which works by temporarily off-loading the joint for 6–8 weeks, is becoming a novel joint-sparing alternative for younger OA sufferers. The biological mechanisms behind KJD structural improvements remain poorly understood but likely involve joint-resident regenerative cells including multipotent stromal cells (MSCs). In this study, we hypothesized that KJD leads to beneficial cartilage-anabolic and anti-catabolic changes in joint-resident MSCs and investigated gene expression profiles of synovial fluid (SF) MSCs following KJD as compared with baseline. To obtain further insights into the effects of local biomechanics on MSCs present in late OA joints, SF MSC gene expression was studied in a separate OA arthroplasty cohort and compared with subchondral bone (SB) MSCs from medial (more loaded) and lateral (less loaded) femoral condyles from the same joints. In OA arthroplasty cohort (n = 12 patients), SF MSCs expressed lower levels of ossification- and hypotrophy-related genes [bone sialoprotein (IBSP), parathyroid hormone 1 receptor (PTH1R), and runt-related transcription factor 2 (RUNX2)] than did SB MSCs. Interestingly, SF MSCs expressed 5- to 50-fold higher levels of transcripts for classical extracellular matrix turnover molecules matrix metalloproteinase 1 (MMP1), a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5), and tissue inhibitor of metalloproteinase-3 (TIMP3), all (p < 0.05) potentially indicating greater cartilage remodeling ability of OA SF MSCs, compared with SB MSCs. In KJD cohort (n = 9 patients), joint off-loading resulted in sustained, significant increase in SF MSC colonies’ sizes and densities and a notable transcript upregulation of key cartilage core protein aggrecan (ACAN) (weeks 3 and 6), as well as reduction in pro-inflammatory C–C motif chemokine ligand 2 (CCL2) expression (weeks 3 and 6). Additionally, early KJD changes (week 3) were marked by significant increases in MSC chondrogenic commitment markers gremlin 1 (GREM1) and growth differentiation factor 5 (GDF5). In combination, our results reveal distinct transcriptomes on joint-resident MSCs from different biomechanical environments and show that 6-week joint off-loading leads to transcriptional changes in SF MSCs that may be beneficial for cartilage regeneration. Biomechanical factors should be certainly considered in the development of novel MSC-based therapies for OA.

Less mechanical loading attenuates osteoarthritis by reducing cartilage degeneration, subchondral bone remodelling, secondary inflammation, and activation of NLRP3 inflammasome

Aims

Osteoarthritis (OA) is a disabling joint disorder and mechanical loading is an important pathogenesis. This study aims to investigate the benefits of less mechanical loading created by intermittent tail suspension for knee OA.

Methods

A post-traumatic OA model was established in 20 rats (12 weeks old, male). Ten rats were treated with less mechanical loading through intermittent tail suspension, while another ten rats were treated with normal mechanical loading. Cartilage damage was determined by gross appearance, Safranin O/Fast Green staining, and immunohistochemistry examinations. Subchondral bone changes were analyzed by micro-CT and tartrate-resistant acid phosphatase (TRAP) staining, and serum inflammatory cytokines were evaluated by enzyme-linked immunosorbent assay (ELISA).

Results

Our radiographs showed that joint space was significantly enlarged in rats with less mechanical loading. Moreover, cartilage destruction was attenuated in the less mechanical loading group with lower histological damage scores, and lower expression of a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-5, matrix metalloproteinase (MMP)-3, and MMP-13. In addition, subchondral bone abnormal changes were ameliorated in OA rats with less mechanical loading, as reduced bone mineral density (BMD), bone volume/tissue volume (BV/TV), and number of osteophytes and osteoclasts in the subchondral bone were observed. Finally, the level of serum inflammatory cytokines was significantly downregulated in the less mechanical loading group compared with the normal mechanical loading group, as well as the expression of NACHT, LRR, and PYD domains-containing protein 3 (NLRP3), caspase-1, and interleukin 1β (IL-1β) in the cartilage.

Conclusion

Less mechanical loading alleviates cartilage destruction, subchondral bone changes, and secondary inflammation in OA joints. This study provides fundamental insights into the benefit of non-weight loading rest for patients with OA.

Cite this article: Bone Joint Res 2020;9(10):731–741.

Eliminating senescent chondrogenic progenitor cells enhances chondrogenesis under intermittent hydrostatic pressure for the treatment of OA

Background

Osteoarthritis (OA) is a major cause of limb dysfunction, and distraction arthroplasty which generates intermittent hydrostatic pressure (IHP) is an effective approach for OA treatment. However, the result was not always satisfactory and the reasons remained unresolved. Because aging is recognized as an important risk factor for OA and chondrogenic progenitor cells (CPCs) could acquire senescent phenotype, we made a hypothesis that CPCs senescence could have harmful effect on chondrogenesis and the outcome of distraction arthroplasty could be improved by eliminating senescent CPCs pharmacologically.

Methods

The role of senescent CPCs on distraction arthroplasty was first determined by comparing the cartilage samples from the failure and non-failure patients. Next, the biological behaviors of senescent CPCs were observed in the in vitro cell culture and IHP model. Finally, the beneficial effect of senescent CPCs clearance by senolytic dasatinib and quercetin (DQ) on cartilage regeneration was observed in the in vitro and in vivo IHP model.

Results

Larger quantities of senescent CPCs along with increased IL-1 β secretion were demonstrated in the failure patients of distraction arthroplasty. Senescent CPCs revealed impaired proliferation and chondrogenic capability and also had increased IL-1 β synthesis, typical of senescence-associated secretory phenotype (SASP). CPCs senescence and SASP formation were mutually dependent in vitro. Greater amounts of senescent CPCs were negatively correlated with IHP-induced chondrogenesis. In contrast, chondrogenesis could be significantly improved by DQ pretreatment which selectively induced senescent CPCs into apoptosis in the in vitro and in vivo IHP model. Mechanistically, senescent CPCs elimination could decrease SASP formation and therefore promote the proliferation and chondrogenic regeneration capacity of the surrounding survived CPCs under IHP stimulation.

Conclusions

Eliminating senescent CPCs by senolytics could decrease SASP formation and improve the result of joint distraction arthroplasty effectively. Our study provided a novel CPCs senescence-based therapeutic target for improving the outcome of OA treatment.

Functionalized Polycaprolactone/Hydroxyapatite Composite Microspheres for Promoting Bone Consolidation in a Rat Distraction Osteogenesis Model

Distraction osteogenesis (DO) is an ideal model to study bone regeneration. The major limitation is the relatively long period required for new bone consolidation. Here, we investigated whether the application of polycaprolactone (PCL) and hydroxyapatite (HA) composite microspheres could enhance bone formation in DO. Pure PCL microspheres and composite PCL and 10% HA microspheres were synthesized. Bone mesenchymal stem cells isolated from green fluorescent protein rats (GFP-rBMSCs) were cultured with microspheres in a rotary bioreactor system. Scanning electron microscopy was used to examine the microstructures. Osteogenic differentiation of rBMSCs was confirmed. Moreover, PCL/HA (20 mg) and PCL (20 mg) were locally administered into the distraction gap in the rat DO model toward the end of the distraction period. Imaging detection, mechanical and histological examinations were performed to assess the quality of the 4-week regenerates. Results showed that the microspheres were of uniform size and monodisperse. After incubation with rBMSCs in culture, PCL/HA microspheres showed a better ability for cell adhesion and osteogenic differentiation compared with PCL microspheres. In vivo, bone volume/total tissue volume, bone mineral density, and mechanical properties of the new callus were significantly higher in the PCL/HA group compared with the PCL group. Histological analyses confirmed improved bone formation and vascularization in PCL/HA group. We presented an effective protocol for the generation of functionalized microspheres and demonstrated implantation of PCL/HA microspheres into the distraction regenerate could significantly enhance bone consolidation. Thus, the application of PCL/HA composite microspheres may be a novel approach for promoting bone regeneration. This article is protected by copyright. All rights reserved © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:961-971, 2020.

Molecular Insights Into Lysyl Oxidases in Cartilage Regeneration and Rejuvenation

Articular cartilage remains among the most difficult tissues to regenerate due to its poor self-repair capacity. The lysyl oxidase family (LOX; also termed as protein-lysine 6-oxidase), mainly consists of lysyl oxidase (LO) and lysyl oxidase-like 1-4 (LOXL1-LOXL4), has been traditionally defined as cuproenzymes that are essential for stabilization of extracellular matrix, particularly cross-linking of collagen and elastin. LOX is essential in the musculoskeletal system, particularly cartilage. LOXs-mediated collagen cross-links are essential for the functional integrity of articular cartilage. Appropriate modulation of the expression or activity of certain LOX members selectively may become potential promising strategy for cartilage repair. In the current review, we summarized the advances of LOX in cartilage homeostasis and functioning, as well as copper-mediated activation of LOX through hypoxia-responsive signaling axis during recent decades. Also, the molecular signaling network governing LOX expression has been summarized, indicating that appropriate modulation of hypoxia-responsive-signaling-directed LOX expression through manipulation of bioavailability of copper and oxygen is promising for further clinical implications of cartilage regeneration, which has emerged as a potential therapeutic approach for cartilage rejuvenation in tissue engineering and regenerative medicine. Therefore, targeted regulation of copper-mediated hypoxia-responsive signalling axis for selective modulation of LOX expression may become potential effective therapeutics for enhanced cartilage regeneration and rejuvenation in future clinical implications.

Downregulation of HMGB1 by miR-103a-3p Promotes Cell Proliferation, Alleviates Apoptosis and in Flammation in a Cell Model of Osteoarthritis

Background

MiR-103a-3p is a small non-coding RNA and has been reported to be involved in osteogenic proliferation and differentiation, but the role of miR-103a-3p in human osteoarthritis (OA) remains unclear.

Objectives

In this study, we aimed to explore its function and molecular target in chondrocytes during OA pathogenesis.

Materials and Methods

Total 12 experimental OA rat models, together with 12 rats without knee OA lesions were established and cartilage samples were collected. Chondrocytes were treated with LPS in vitro. MiR-103a-3p expression was detected in articular cartilage tissues and chondrocytes using quantitative real-time PCR. Knee OA chondrocytes were transfected with miR-103a-3p mimics, and siHMGB1, respectively. Then cellular proliferation, apoptosis, apoptosis related factors and inflammatory cytokines were analyzed by MTT, flow cytometry, western blot, caspase-3 activity and ELISA, respectively. Potential targets of miR-103a-3p were predicted using series of bioinformatics analysis, then confirmed by luciferase reporter assay.

Results

We first found miR-103a-3p was significantly down-regulated in the articular cartilage tissues from experimental OA rats, as well as in chondrocytes treated with LPS in vitro. The gain-of-function assay further demonstrated that up-regulation of miR-103a-3p significantly promoted cell proliferation, inhibited apoptosis and inflammation, which was accompanied with elevated expression of PCNA, and reduced expression of caspase-3, PARP, IL-1β, IL-6, IL-10 and TNF-α. Furthermore, high mobility group box 1 (HMGB1), an important inflammatory mediator of OA, was a target of miR-103a-3p. Moreover, knockdown of HMGB1 mimicked the effects of miR-103a-3p on chondrocytes treated with LPS.

Conclusions

Taken together, our study suggests that miR-103a-3p inhibits chondrocyte apoptosis and inflammation in OA, which appears to be an attractive approach to OA treatment.

Knee muscle atrophy is a risk factor for development of knee osteoarthritis in a rat model

Objectives

The objective of this study was to investigate the effect of botulinum toxin type A (BTX-A)-induced quadriceps muscle atrophy on the cartilage and subchondral bone in an otherwise intact rat joint model.

Methods

The rat right quadriceps muscle atrophy was established by intramuscular injection of BTX-A. Twenty-four rats were divided randomly into 3 groups: The BTX-A-treated 4-week group; the BTX-A-treated 8-week group; and the control group injected with phosphate buffer saline were observed for 8 weeks. Muscle atrophy level was measured by weighing and histology examinations. Serum interleukin-1β level was tested by ELISA (enzyme linked immunosorbent assay); the subchondral bone was analysed by micro-computed tomography and the cartilage was measured by histology examinations (gross view, haematoxylin and eosin staining and Safranin-O/fast green staining) and immunohistochemistry test {collagen X [ColX]}.

Results

BTX-A intramuscular injection led to muscle atrophy. Characteristics of muscle atrophy appeared in two BTX-A-injected groups but not in the control group. Quadriceps atrophy did not affect interleukin-1β level in serum, but resulted in subchondral bone abnormal changes with reduced bone volume/total tissue volume ​and increased Structure Model Index. Furthermore, the more the severe cartilage damage, the higher the histologic damage scores, followed by the higher the percentage of collagen X-positive chondrocytes caused by muscle atrophy.

Conclusions

Quadriceps muscle atrophy triggered the subchondral bone abnormal change and cartilage degeneration, which would be a risk factor for development of osteoarthritis.

The translational potential of this article

Our results indicate that anti-quadriceps muscle atrophy can be a candidate therapeutic target in the prevention of knee osteoarthritis.

Hip arthrodiastasis combined with core decompression and diamond concept for postcollapse femoral head avascular necrosis

In postcollapse hip avascular necrosis (AVN), the femoral head cannot be salvaged, necessitating total hip replacement. We report a case of a 39-year-old woman who developed idiopathic femoral head AVN with marked symptoms and radiological evidence of articular surface collapse. We treated her with core decompression combined with the 'diamond concept' (implantation of bone marrow concentrate, a growth factor and bone graft substitute) and distracted the hip joint with external fixator. Four years postoperatively the articular surface has been restored and the patient reports excellent quality of life. Hip arthrodiastasis with core decompression and 'diamond concept' regeneration could be considered a treatment option in advanced AVN of the femoral head.

The role of joint distraction in the treatment of knee osteoarthritis: a systematic review and quantitative analysis

Introduction

Knee osteoarthritis is a major cause of pain and disability for which joint distraction is a potential treatment to delay the need for knee arthroplasty. This systematic review aims to assess the short- and long-term clinical and structural outcomes following knee joint distraction (KJD).

Methods

MEDLINE, EMBASE, Scopus, and Web of Science databases were searched from the date of inception to 26th June 2019. Clinical studies investigating joint distraction for knee osteoarthritis with outcomes including ∆WOMAC index, ∆VAS pain score, and ∆joint space width were included. The review protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) – CRD42018087032.

Results

Nine studies comprising a total of 507 patients were included. There were four randomized controlled trials (RCTs), five open prospective cohort studies, and one case series. Overall, there were significant improvements in WOMAC index, VAS pain score and joint space width following KJD, which persisted up to 9 years. KJD also demonstrated comparable clinical outcomes with high tibial osteotomy and total knee arthroplasty.

Conclusion

There is moderate quality evidence supporting the beneficial outcomes of joint distraction for knee osteoarthritis. Larger RCTs with longer follow-up (>1 year) are necessary to establish the true effect size of this procedure.

[Mechanical stress promotes cartilage repair in inflammatory environment]

OBJECTIVE

To investigate the effect and mechanism of mechanical stress on cartilage repair in inflammatory environment.

METHODS

The chondrogenic progenitor cells (CPCs) were isolated from the knee joint cartilage of patients with osteoarthritis (OA) undergoing total knee arthroplasty. The CPCs were cultured and expanded in a 3-D scaffold constructed with alginate. Intermittent hydrostatic pressure (IHP) was applied in a inflammatory environment induced by IL-1β, and Western blot was used to detect the expression of MAPK signaling pathway proteins. Cell proliferation was detected by CCK-8 method, and the expression of related genes like matrix metallo-proteinases 13 (MMP-13) and a disintegrins and metalloproteinase with thrombospondin motif 5 (ADAMTS-5) was detected by real-time RT-PCR. The anterior cruciate ligament of the rats was cut to construct the knee joint OA model, and the appropriate mechanical stress was constructed with external fixation to distract the knee joint in order to observe the repair of the cartilage and to explore its mechanism.

RESULTS

Adding 0.01 ng/ml IL-1β in cell culture inhibited the proliferation of CPCs. After IHP application, the expression of MAPK pathway protein was decreased, the mRNA expression of MMP-13 and ADAMTS-5 was reduced. The inhibition of IL-1β on CPCs was counteracted by IHP. Four weeks after the anterior cruciate ligament resected, the articular cartilage degeneration was observed in rats. The Mankin score in the OA treatment (joint distraction) group was lower, and the cartilage repair was better than that of the control group (P<0.01). Animal experiments found that the suitable mechanical stress reduced the expression of P-p38, MMP-13 and COLL-X, inhibited cartilage cells apoptosis and promoted the repair of OA cartilage.

CONCLUSIONS

Mechanical stress can promote the proliferation of CPCs, reduce the expression of matrix degrading enzymes, and promote the repair of OA cartilage by inhibiting MAPK signaling pathway.

Sustained Release SDF-1α/TGF-β1-Loaded Silk Fibroin-Porous Gelatin Scaffold Promotes Cartilage Repair

Continuous delivery of growth factors to the injury site is crucial to creating a favorable microenvironment for cartilage injury repair. In the present study, we fabricated a novel sustained-release scaffold, stromal-derived factor-1α (SDF-1α)/transforming growth factor-β1 (TGF-β1)-loaded silk fibroin-porous gelatin scaffold (GSTS). GSTS persistently releases SDF-1α and TGF-β1, which enhance cartilage repair by facilitating cell homing and chondrogenic differentiation. Scanning electron microscopy showed that GSTS is a porous microstructure and the protein release assay demonstrated the sustainable release of SDF-1α and TGF-β1 from GSTS. Bone marrow-derived mesenchymal stem cells (MSCs) maintain high in vitro cell activity and excellent cell distribution and phenotype after seeding into GSTS. Furthermore, MSCs acquired enhanced chondrogenic differentiation capability in the TGF-β1-loaded scaffolds (GSTS or GST: loading TGF-β1 only) and the conditioned medium from SDF-1α-loaded scaffolds (GSTS or GSS: loading SDF-1α only) effectively promoted MSCs migration. GSTS was transplanted into the osteochondral defects in the knee joint of rats, and it could promote cartilage regeneration and repair the cartilage defects at 12 weeks after transplantation. Our study shows that GSTS can facilitate in vitro MSCs homing, migration, chondrogenic differentiation and SDF-1α and TGF-β1 have a synergistic effect on the promotion of in vivo cartilage forming. This SDF-1α and TGF-β1 releasing GSTS have promising therapeutic potential in cartilage repair.

Joint distraction for knee osteoarthritis: protocol for a systematic review and meta-analysis

BACKGROUND

Osteoarthritis is a degenerative joint disease that is highly prevalent worldwide. Knee osteoarthritis is the most common form of osteoarthritis and is a major cause of pain and disability. However, there remains a lack of treatments available that have demonstrated effectiveness in stopping or reversing the degenerative process. Joint distraction has emerged as a viable alternative in the treatment of knee osteoarthritis to delay the need for knee arthroplasty.

METHODS

An electronic search will be conducted on MEDLINE, EMBASE, Web of Science, CINAHL, Cochrane and EBSCO databases. Clinical studies investigating joint distraction for knee osteoarthritis, which reported clinical or structural outcomes including ∆WOMAC index, ∆VAS pain score and ∆joint space width will be included. Risk of bias will be assessed using the Newcastle-Ottawa Scale for observational studies and Cochrane Collaboration tool for randomised controlled trials. Quality of studies will be assessed using the modified Coleman methodology score.

DISCUSSION

This systematic review will summarise the short- and long-term clinical and structural outcomes following joint distraction for knee osteoarthritis. The findings from this review will establish the quality of currently available evidence, which will determine the need for further studies to establish the true effect size of this procedure.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018087032.

GPR120 is an important inflammatory regulator in the development of osteoarthritis

Background

The aim of this study was to investigate the regulatory role of G-protein coupled receptor 120 (GPR120) in the development and progression of osteoarthritis (OA).

Methods

GPR120 knockout (KO) and wild-type (WT) mice were used to create an animal model of OA by means of anterior cruciate ligament transection (ACLT) surgery. The severity of OA was staged and evaluated by histological examination, microcomputed tomography scan and enzyme-linked immunosorbent assay (ELISA). The anti-inflammatory effects of the GPR120 agonist docosahexaenoic acid (DHA) on human chondrocytes were further evaluated by specific inflammatory markers. In addition, the healing progression of a skin defect model was determined with histological assays.

Results

The GPR120-KO mice displayed an accelerated development of OA after ACLT. The secondary inflammation, cartilage degeneration, and subchondral bone aberrant changes were significantly elevated in the early phase of OA in KO mice relative to those in WT mice. In addition, we found that GPR120 levels were downregulated in OA patients compared with control subjects, whereas GPR120 activation with DHA exhibited anti-inflammatory effects in primary human chondrocytes in vitro. Moreover, results from the skin defect model showed that GPR120 agonism with DHA enhanced wound repair in mice, as shown by the downregulation of the number of CD68⁺ cells.

Conclusions

Our study suggests that GPR120 is an important inflammatory mediator during the development of OA, and that it is a potential marker for the diagnosis of high-risk patients with OA.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1660-6) contains supplementary material, which is available to authorized users.

Subchondral bone fragility with meniscal tear accelerates and parathyroid hormone decelerates articular cartilage degeneration in rat osteoarthritis model

The aims of this study were to investigate the influence of subchondral bone fragility (SBF) on the progression of the knee osteoarthritis by using a novel rat model, and to examine the preventive effect of parathyroid hormone (PTH) on cartilage degeneration. First, 40 rats were assigned to the following four groups: Sham, SBF, Medial meniscal tear (MMT), and MMT + SBF groups. In SBF and MMT + SBF groups, we induced SBF by microdrilling the subchondral bone. Second, 10 additional rats were randomly assigned to the following two groups: MMT + SBF + saline and MMT + SBF + PTH groups. Osteoarthritic changes in the articular cartilage and subchondral bone were evaluated using safranin-O/fast green staining, matrix metalloproteinase-13 (MMP-13), and type X collagen immunohistochemistry, toluidine blue staining, and micro-CT scanning. The combination of SBF and meniscal tear increased the number of mast cells in the subchondral bone, and led to the abnormal subchondral bone microarchitecture, such as abnormally decreased trabecular number and increased trabecular thickness, compared with meniscal tear alone. Moreover, SBF with meniscal tear enhanced articular cartilage degeneration and increased the expression of MMP-13 and type X collagen, compared with meniscal tear alone. The administration of PTH decreased the number of mast cells in the subchondral bone and improved the microstructural parameters of the subchondral bone, and delayed the progression of articular cartilage degeneration. These results suggest that SBF is one of the factors underlying the osteoarthritis development, especially in knees with traumatic osteoarthritis, and that the administration of PTH is a potential therapeutic treatment for preventing OA progression. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1959-1968, 2018.

Comparison between in vitro and in vivo cartilage overloading studies based on a systematic literature review

Methodological differences between in vitro and in vivo studies on cartilage overloading complicate the comparison of outcomes. The rationale of the current review was to (i) identify consistencies and inconsistencies between in vitro and in vivo studies on mechanically-induced structural damage in articular cartilage, such that variables worth interesting to further explore using either one of these approaches can be identified; and (ii) suggest how the methodologies of both approaches may be adjusted to facilitate easier comparison and therewith stimulate translation of results between in vivo and in vitro studies. This study is anticipated to enhance our understanding of the development of osteoarthritis, and to reduce the number of in vivo studies. Generally, results of in vitro and in vivo studies are not contradicting. Both show subchondral bone damage and intact cartilage above a threshold value of impact energy. At lower loading rates, excessive loads may cause cartilage fissuring, decreased cell viability, collagen network de-structuring, decreased GAG content, an overall damage increase over time, and low ability to recover. This encourages further improvement of in vitro systems, to replace, reduce, and/or refine in vivo studies. However, differences in experimental set up and analyses complicate comparison of results. Ways to bridge the gap include (i) bringing in vitro set-ups closer to in vivo, for example, by aligning loading protocols and overlapping experimental timeframes; (ii) synchronizing analytical methods; and (iii) using computational models to translate conclusions from in vitro results to the in vivo environment and vice versa. © 2018 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. J Orthop Res 9999:1-11, 2018.

Three-dimensional visualization and pathologic characteristics of cartilage and subchondral bone changes in the lumbar facet joint of an ovariectomized mouse model

BACKGROUND CONTEXT

Low back pain (LBP) is more prevalent among postmenopausal women than men. Ovariectomy (OVX) is an established animal model that mimics the estrogen deficiency of postmenopausal women. Little is known about the three-dimensional (3D) morphologic properties of cartilage and subchondral bone changes in the lumbar facet joint (LFJ) of an OVX mouse model.

PURPOSE

The purpose of this study was to characterize the 3D morphologic change of cartilage and subchondral bone in the LFJ of an OVX mouse model.

STUDY DESIGN

Three-dimensional visualization and a histologic study on degenerative changes in cartilage and subchondral bone in the LFJ of an OVX mouse model were conducted.

MATERIALS AND METHODS

Ovariectomy is performed to mimic postmenopausal changes in adult female mice. We present an imaging tool for 3D visualization of the pathologic characteristics of cartilage and subchondral bone changes LFJ degradation using propagation-based phase-contrast computed tomography (PPCT). The samples were further dissected, fixed, and stained for histologic examination.

RESULTS

Propagation-based phase-contrast computed tomography imaging provides a 3D visualization of altered cartilage with a simultaneous high detail of the subchondral bone abnormalities in an OVX LFJ model. A quantitative analysis demonstrated that the cartilage volume, the surface area, and thickness were decreased in the OVX group compared with the control group (p<.05). Meanwhile, these decreases were accompanied by an obvious destruction of the subchondral bone surface and a loss of trabecular bone in the OVX group (p<.05). The delineation of the 3D pathologic changes in the PPCT imaging was confirmed by a histopathologic method with Safranin-O staining. Tartrate-resistant acid phosphatase staining revealed an increased number of osteoclasts in the subchondral bone of the OVX mice compared with that of the control group.

CONCLUSIONS

These results demonstrated that a mouse model of OVX-induced LFJ osteoarthritis (OA)-like changes was successfully established and showed a good resemblance to the human OA pathology. Propagation-based phase-contrast computed tomography has great potential to becomea powerful 3D imaging method to comprehensively characterize LFJ OA and to effectively monitor therapeutics. Moreover, degenerative LFJ possesses a severe morphologic change in the subchondral bone, may be the source of postmenopausal LBP, and has the potential to be a novel therapeutic target for LBP treatment.

Spinacia oleracea extract attenuates disease progression and sub-chondral bone changes in monosodium iodoacetate-induced osteoarthritis in rats

Background

Spinacia oleracea is an important dietary vegetable in India and throughout the world and has many beneficial effects. It is cultivated globally. However, its effect on osteoarthritis that mainly targets the cartilage cells remains unknown. In this study we aimed to evaluate the anti-osteoarthritic and chondro-protective effects of SOE on chemically induced osteoarthritis (OA).

Methods

OA was induced by intra-patellar injection of monosodium iodoacetate (MIA) at the knee joint in rats. SOE was then given orally at 250 and 500 mg.kg^− 1 day^− 1 doses for 28 days to these rats. Anti-osteoarthritic potential of SOE was evaluated by micro-CT, mRNA and protein expression of pro-inflammatory and chondrogenic genes, clinically relevant biomarker’s and behavioural experiments.

Results

In vitro cell free and cell based assays indicated that SOE acts as a strong anti-oxidant and an anti-inflammatory agent. Histological analysis of knee joints at the end of the experiment by safranin-o and toluidine blue staining established its protective effect. Radiological data corroborated the findings with improvement in the joint space and irregularity of the articular and atrophied femoral condyles and tibial plateau. Micro-CT analysis of sub-chondral bone indicated that SOE had the ability to mitigate OA effects by increasing bone volume to tissue volume (BV/TV) which resulted in decrease of trabecular pattern factor (Tb.Pf) by more than 200%. SOE stimulated chondrogenic marker gene expression with reduction in pro-inflammatory markers. Purified compounds isolated from SOE exhibited increased Sox-9 and Col-II protein expression in articular chondrocytes. Serum and urine analysis indicated that SOE had the potential to down-regulate glutathione S-transferase (GST) activity, clinical markers of osteoarthritis like cartilage oligometric matrix protein (COMP) and CTX-II. Overall, this led to a significant improvement in locomotion and balancing activity in rats as assessed by Open-field and Rota rod test.

Conclusion

On the basis of in vitro and in vivo experiments performed with Spinacea oleracea extract we can deduce that SOE has the ability to alleviate the MIA induced deleterious effects.

Electronic supplementary material

The online version of this article (10.1186/s12906-018-2117-9) contains supplementary material, which is available to authorized users.

Porcine brain extract promotes osteogenic differentiation of bone marrow derived mesenchymal stem cells and bone consolidation in a rat distraction osteogenesis model

Distraction osteogenesis (DO) is the gold standard to treat large bone defects, but long consolidation period is a major limitation. Innovative efforts to promote osteogenesis are needed. Porcine brain extract (PBE) was reported to enhance the proliferation and differentiation of multiple primary cells. In this study, we aimed to develop a method for collecting PBE and investigate its effects on osteogenic differentiation of rat bone marrow derived mesenchymal stem cells (rBMSCs) and bone consolidation in a rat DO model. The PBE was collected from neonatal brain tissues of porcine fetus and was used to treat rBMSCs. Following PBE treatment (700 ng/ml), osteogenic differentiation was assessed. Further, we locally injected PBE (7 μg/ml, 100μl) or PBS (100μl) into the gap in a Sprague-Dawley (SD) male rat DO model every three days till termination. X-rays, micro-computed tomography, mechanical testing, histology and immunohischemistry examinations were used to exam the quality of the regenerates. The alkaline phosphatase, calcium deposits, and steogenic markers in the PBE treated rBMSCs were significantly increased. In the rat model, new bone properties of bone volume/total tissue volume and mechanical strength were higher in the PBE treated group. Histological analysis also confirmed more mineralized bone after PBE treatment. The current study reports a standard protocol for PBE collection and demonstrated its positive effects on osteogenic differentiation and bone consolidation in DO. Since the PBE is readily available and very cost effective, PBE may be a potential new bio-source to promote bone formation in patients undergo DO treatment.

[Short-term effectiveness of joint distraction by Ilizarov combined with arthroscopic debridement in treatment of knee osteoarthritis]

Objective

To investigate the short-term effectiveness of joint distraction by Ilizarov combined with arthroscopic debridement in the treatment of knee osteoarthritis (KOA).

Methods

Between January 2014 and January 2015, 15 patients (15 knees) with KOA were treated using arthroscopic debridement assisting with the Ilizarov distraction technology. There were 7 males and 8 females, aged from 45 to 64 years (mean, 55 years). The left knee and the right knee were involved in 6 and 9 cases respectively. The disease duration was 2.0-9.5 years (median, 6 years). They all had received conservative treatment for 6 months and got poor clinical improvement. The preoperative visual analogue scale (VAS) score, the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) score, the knee injury and osteoarthritis outcome score (KOOS), the range of motion (ROM) for knee, and the radiographic joint space width were 76.2±8.8, 59.3±5.7, 44.3±7.2, (75±21)°, and (2.5±0.4) mm respectively. According to Kellgren-Lawrence grade system, 11 cases were rated as grade III and 4 cases as grade IV.

Results

There was no poor incision healing, infection, and deep vein thrombosis. All the 15 patients were followed up 12-18 months (mean, 15.5 months). Patients achieved pain relief. The knee activity was obviously improved. The postoperative VAS score, WOMAC score, KOOS score, and ROM at 12 months were 20.9±7.8, 38.2±5.5, 92.1±6.9, and (118±14)° respectively, showing significant difference when compared with preoperative ones ( t=18.213, P=0.000; t=10.317, P=0.000; t=18.564, P=0.000; t=6.599, P=0.000). Postoperative X-ray film showed that joint space width at 12 months was (3.8±0.3) mm, showing significant difference when compared with preoperative one ( t=10.070, P=0.000).

Conclusion

Joint distraction by Ilizarov combined with arthroscopic debridement can effectively relieve pain, improve the function and quality of life. It was beneficial to cartilaginous tissue repair and delaying the degenerative process of KOA. The short-term effectiveness is satisfactory.

WITHDRAWN: 3D visualization and pathological characteristics of cartilage and subchondral bone changes in the lumbar facet joint of an Ovariectomized mouse model

The Publisher regrets that this article is an accidental duplication of an article that has already been published, http://dx.doi.org/10.1016/j.spinee.2017.11.009. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

Attenuation of subchondral bone abnormal changes in osteoarthritis by inhibition of SDF-1 signaling

BACKGROUND

Current conservative treatments for osteoarthritis (OA) are largely symptoms control therapies. Further understanding on the pathological mechanisms of OA is crucial for new pharmacological intervention.

OBJECTIVE

In this study, we investigated the role of Stromal cell-derived factor-1(SDF-1) in regulating subchondral bone changes during the progression of OA.

METHODS

Clinical samples of different stages of OA severity were analyzed by histology staining, micro-CT, enzyme-linked immunosorbent assay (ELISA) and western blotting, to compare SDF-1 level in subchondral bone. The effects of SDF-1 on human mesenchymal stem cells (MSCs) osteogenic differentiation were evaluated. In vivo assessment was performed in an anterior cruciate ligament transaction plus medial meniscus resection in the SD rats. The OA rats received continuous infusion of AMD3100 (SDF-1 receptor blocker) in osmotic mini-pump implanted subcutaneously for 6 weeks. These rats were then terminated and subjected to the same in vitro assessments as human OA samples.

RESULTS

SDF-1 level was significantly elevated in the subchondral bone of human OA samples. In the cell studies, the results showed SDF-1 plays an important role in osteogenic differentiation of MSCs. In the OA animal studies, there were less cartilage damage in the AMD3100-treated group; microCT results showed that the subchondral bone formation was significantly reduced and so did the number of positive Nestin or Osterix cells in the subchondral bone region.

CONCLUSIONS

Higher level of SDF-1 may induce the subchondral bone abnormal changes in OA and inhibition of SDF-1 signaling could be a potential therapeutic approach for OA.

Staphylococcal enterotoxin C2 expedites bone consolidation in distraction osteogenesis

Distraction osteogenesis (DO) technique could be used to manage large-size bone defect successfully, but DO process usually requires long duration of bone consolidation. Innovative approaches for augmenting bone consolidation are of great need. Staphylococcal enterotoxin C2 (SEC2) has been found to suppress osteoclastogenesis of mesenchymal stem cells in vitro. In this study, we investigated the effect of SEC2 on proliferation and osteogenic differentiation of rat bone marrow derived mesenchymal stem cells (rBMSCs). Further, we locally administrated SEC2 (10 ng/ml) or PBS into the distraction gap in Sprague-Dawley male rat DO model every 3 days till termination at 3 and 6 weeks. The regenerates were subjected to X-rays, micro-computed tomography, mechanical testing, histology, and immunohischemistry examinations to assess new bone quality. SEC2 had no effect on cell viability. The calcium deposition was remarkably increased and osteogenic marker genes were significantly up-regulated in rBMSCs treated with SEC2. In rat DO model, SEC2 group had higher bone volume/total tissue volume in the regenerates. At 6 weeks, mechanical properties were significantly higher in SEC2-treated tibiae comparing to the control group. Histological analysis confirmed that the new bone had improved quality in SEC2 treated group, where the osteocalcin and osterix expression in the regenerates was up-regulated, indicating faster bone formation. The current study demonstrated that SEC2 local injection promotes osteogenesis and enhanced bone consolidation in DO. The findings support application of SEC2 as a potential novel strategy to expedite bone consolidation in patients undergoing DO treatment. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1215-1225, 2017.

Human fetal mesenchymal stem cell secretome enhances bone consolidation in distraction osteogenesis

BACKGROUND

Distraction osteogenesis (DO) is one of the most dramatic reconstructive techniques for inducing bone regeneration, but it involves an undesirably long period for bone consolidation. Developing innovative approaches to enhance bone consolidation is a burning need. Human fetal mesenchymal stem cells (hFMSCs) have been shown to express more primitive developmental genes than those of human adult mesenchymal stem cells (hAMSCs), which is a preferable source for cell therapy and tissue regeneration. In the present study, we investigated the immunogenicity of using the human mesenchymal stem cell (MSC) secretome on rat cells, the effects of secretome on osteogenic differentiation of rat bone marrow-derived MSCs (rBMSCs), and the potential application of hFMSC secretome in promoting bone consolidation in a rat DO model.

METHODS

Secretome was collected from MSC culture and was used to treat rBMSCs. Following secretome treatment, cell proliferation, alkaline phosphatase staining, Alizarin Red S staining, and mRNA expression of osteogenic differentiation-related genes (including ALP, Runx2, OCN, OPN, and Osx) in the rBMSCs were checked, as well as mixed rat peripheral blood lymphocyte reaction. hFMSC secretome was injected locally into the regenerates from the end of lengthening every 3 days in the rat DO model, until termination. The regenerates were subject to weekly x-rays, micro-computed tomography (μCT) and mechanical testing examination. The bone quality was assessed by histology and immunohistochemistry examinations.

RESULTS

Compared to the secretome from rBMSCs and hAMSCs, hFMSC secretome had the best osteogenic induction ability and low immunogenicity. hFMSC secretome with different doses showed no effect on cell viability. hFMSC secretome at the dose of 100 μg/μl could significantly increase the expression of alkaline phosphatase and all the osteogenic marker genes, as well as the amount of calcium deposits in the rBMSCs. Finally, the local application of hFMSC secretome in distraction regenerates in a rat DO model significantly improved bone consolidation according to the results of μCT, mechanical test, and histological and immunohistochemistry analysis.

CONCLUSIONS

The current study demonstrated that hFMSC secretome promotes osteogenesis of rBMSCs and bone consolidation during DO. hFMSC secretome may be a new therapeutic strategy to enhance bone consolidation in patients undergoing DO treatment.

Distraction to treat knee osteoarthritis

The objective of this article is to review data on joint distraction used to treat knee osteoarthritis. Joint distraction is a surgical procedure in which the two bony ends of the joint are gradually pulled apart then kept separated for 2 months in an external fixation frame. Weight bearing is continued to ensure variations in hydrostatic pressure within the joint. In published studies, joint distraction provided substantial clinical and structural improvements in patients with knee osteoarthritis, delaying joint replacement surgery for at least 2 years. Animal studies showed that joint distraction was associated with decrease in the secondary inflammatory response, cartilage breakdown, and subchondral bone remodeling. In vitro, the intermittent application of hydrostatic pressure stimulated the production of extracellular matrix, particularly in joints with osteoarthritis. Nevertheless, several considerations invite caution when considering the more widespread use of joint distraction. Published studies have short follow-ups and small sample sizes. In addition, the high frequency of pin tract infection is of concern, since most patients eventually require knee replacement surgery. These two considerations indicate a need for longer-term prospective studies of patient cohorts.

Weekly injections of Hylan G-F 20 delay cartilage degeneration in partial meniscectomized rat knees

Background

Cross-linked hyaluronan—also called Hylan G-F 20—is a medical device developed to treat osteoarthritis of the knee. However, it is still controversial whether Hylan G-F 20 has a cartilage protective effect in trauma-induced osteoarthritis. We investigated whether Hylan G-F 20 delayed osteoarthritis progression in a partial meniscectomized rat model.

Methods

Lewis rats were used for the experiments. The anterior medial meniscus was resected at the level of the medial collateral ligament in both knees. From 1 week after the surgery, 50 μl of Hylan G-F 20 was injected weekly into the left knee and phosphate buffered saline was injected into the right knee. Cartilage was evaluated for macroscopic findings, histology with safranin-o, and expression of type II collagen at 2, 4, and 8 weeks. Synovitis was also evaluated, and immunohistochemical analysis was performed for ED1.

Results

Macroscopic findings demonstrated that India ink positive area, representing fibrillated cartilage, was significantly smaller in the Hylan G-F 20 group than in the control group at 2, 4, and 8 weeks (n = 5). There were no significant differences in osteophyte score between the Hylan G-F 20 group and the control group at 2, 4, and 8 weeks.

Histologically, the cartilage in the medial tibial plateau was destroyed at 8 weeks in the control group, while type II collagen expression was still observed at 8 weeks in the Hylan G-F 20 group. OARSI score for cartilage histology was significantly lower in the Hylan G-F 20 group than in the control group at 4 and 8 weeks (n = 5). There were no significant differences in synovial cell number or modified synovitis score between the Hylan G-F 20 group and the control group at 2, 4, and 8 weeks (n = 5). In the Hylan G-F 20 group, foreign bodies surrounded by ED1 positive macrophages were observed in the synovium.

Conclusion

Weekly injections of Hylan G-F 20 starting 1 week after surgery delayed cartilage degeneration after meniscectomy in a rat model. Synovitis induced by meniscectomy was not alleviated by Hylan G-F 20. Insoluble gels were observed in the synovium after the Hylan G-F 20 injection.

Subchondral plate porosity colocalizes with the point of mechanical load during ambulation in a rat knee model of post-traumatic osteoarthritis

OBJECTIVE

This study investigated the association between spatiotemporal cartilage-subchondral bone plate alterations and mechanical load during ambulation in an experimental rat model of destabilized medial meniscus (DMM).

DESIGN

Twelve-week-old Wistar rats (n = 38) underwent DMM surgery on the right knee and sham surgery on the left knee. At 2 and 4 weeks after surgery, subchondral bone changes were evaluated via micro-computed tomography with various knee flexion angles to simulate weight-bearing during rat ambulation under a 3-dimensional motion capture apparatus. Additionally, the biomechanical properties, histology, and ultrastructure of the medial tibia and femoral condyle were evaluated.

RESULTS

Focal subchondral bone plate perforations were confirmed in the medial tibia within 2 weeks after surgery and were aggravated rapidly 2 weeks later. This subchondral plate porosity colocalized with articular cartilage lesions as confirmed by histology and scanning electron microscopy, and coincided with the likely point of contact between the posterior femoral condyle and tibial plateau during ambulation. Biomechanical properties were confirmed at the medial tibia, at which stiffness was reduced to approximately half that of the sham-operated knee at 4 weeks after surgery.

CONCLUSIONS

Cartilage-subchondral bone plate alterations localized in the region of the point of mechanical load during ambulation in DMM-operated knees, at which the mechanical integrity of cartilage was impaired. These results indicate that DMM-induced increases in mechanical load play an important role in the pathogenesis of early post-traumatic osteoarthritis (OA), and it might accelerate the development of the disease via cartilage-subchondral bone plate crosstalk through increased subchondral plate perforations.