Osteoarthritis: toward a comprehensive understanding of pathological mechanism

Isoliquiritigenin, a potential therapeutic agent for treatment of inflammation-associated diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Licorice is a medicinal herb with a 2000-year history of applications in traditional Chinese medicine. Isoliquiritigenin (ISL) is a bioactive chalcone compound isolated from licorice. It has attracted increasing attention in recent years due to its excellent anti-inflammatory activity.

AIM OF THE STUDY

This study is to provide a comprehensive summary of the anti-inflammatory activity of ISL and the underlying molecular mechanisms, and discuss new insights for its potential clinical applications as an anti-inflammation agent.

MATERIALS AND METHODS

We examined literatures published in the past twenty years from PubMed, Research Gate, Web of Science, Google Scholar, and SciFinder, with single or combined key words of "isoliquiritigenin", "inflammation", and "anti-inflammatory".

RESULTS

ISL elicits its anti-inflammatory activity by mediating various cellular processes. It inhibits the upstream of the nuclear factor kappa B (NF-κB) pathway and activates the nuclear factor erythroid related factor 2 (Nrf2) pathway. In addition, it suppresses the NOD-like receptor protein 3 (NLRP3) pathway and restrains the mitogen-activated protein kinase (MAPK) pathway.

CONCLUSIONS

Current studies indicate a great therapeutical potential of ISL as a drug candidate for treatment of inflammation-associated diseases. However, the pharmacokinetics, biosafety, and bioavailability of ISL remain to be further investigated.

XJB-5-131 protects chondrocytes from ferroptosis to alleviate osteoarthritis progression via restoring Pebp1 expression

Background

Osteoarthritis (OA) is the most common age-related musculoskeletal disease. However, there is still a lack of therapy that can modify OA progression due to the complex pathogenic mechanisms. The aim of the study was to explore the role and mechanism of XJB-5-131 inhibiting chondrocytes ferroptosis to alleviate OA progression.

Methods

We treated tert-butyl hydroperoxide (TBHP)-induced ferroptosis of mouse primary chondrocytes with XJB-5-131 in vitro. The intracellular ferroptotic hallmarks, cartilage anabolic and catabolic markers, ferroptosis regulatory genes and proteins were detected. Then we established a mouse OA model via destabilization of the medial meniscus (DMM) surgery. The OA mice were treated with intra-articular injection of XJB-5-131 regularly (2 μM, 3 times per week). After 4 and 8 weeks, we performed micro-CT and histological examination to evaluate the protection role of XJB-5-131 in mouse OA subjects. RNA sequencing analysis was performed to unveil the key downstream gene of XJB-5-131 exerting the anti-ferroptotic effect in OA.

Results

XJB-5-131 significantly suppressed TBHP-induced increases of ferroptotic hallmarks (ROS, lipid peroxidation, and Fe2+ accumulation), ferroptotic drivers (Ptgs2, Pgd, Tfrc, Atf3, Cdo1), while restored the expression of ferroptotic suppressors (Gpx4, Fth1). XJB-5-131 evidently promoted the expression of cartilage anabolic and decreased the expression of cartilage catabolic markers. Moreover, intra-articular injection of XJB-5-131 significantly inhibited the expression of Cox2 and Mmp13, while promoted the expression of Col2a1, Gpx4 and Fth1 in DMM-induced mouse articular cartilage. Further, we identified Pebp1 as a potential target of XJB-5-131 by RNA sequencing analysis. The anti-ferroptosis and chondroprotective effects of XJB-5-131 were significantly diminished by Locostatin, a specific antagonist of Pebp1.

Conclusion

XJB-5-131 significantly protects chondrocytes from ferroptosis in TBHP-induced mouse primary chondrocytes and DMM surgery-induced OA mice model via restoring the expression of Pebp1. XJB-5-131 is a potential therapeutic drug in the management of OA progression.

The Pharmacological Potential of Resveratrol in Reducing Soft Tissue Damage in Osteoarthritis Patients

Osteoarthritis is a degenerative joint disease that causes the cartilage and bone underneath the joint to break down. This causes pain and stiffness. Resveratrol, a polyphenolic compound found in various vegetables, fruits, and red wine, has been studied for its beneficial effects on osteoarthritis. Resveratrol has been shown to target a variety of pathways, including the NF-κB, PI3K/Akt, MAPK/ERK, and AMPK pathways. In particular, resveratrol has been studied for its potential use in treating osteoarthritis, and it has been shown to reduce inflammation, reduce cartilage degradation, and improve joint function. In this review, we discuss the evidence for the pharmacological use of resveratrol in minimizing soft tissue damage associated with osteoarthritis. We summarize the studies on how resveratrol has anti-inflammatory, anti-oxidant, and anti-apoptotic effects, as well as effects on cartilage degradation, osteoblast and synoviocyte proliferation, and cytokine production. We also discuss the possible mechanisms of action of resveratrol in osteoarthritis and its potential as a therapeutic agent. Finally, we discuss the potential risks and adverse effects of long-term resveratrol supplementation. Overall, resveratrol has been found to be a possible treatment for osteoarthritis because of its anti-inflammatory, anti-oxidant, and anti-apoptotic properties, and its ability to control the production of enzymes that break down cartilage, osteoblasts, and synoviocytes. Although numerous clinical studies have demonstrated resveratrol's efficacy as an osteoarthritis management agent, further long-term studies are needed to better understand the safety and potential benefits of using resveratrol for osteoarthritis management.

H3K36 methyltransferase NSD1 protects against osteoarthritis through regulating chondrocyte differentiation and cartilage homeostasis

Osteoarthritis (OA) is one of the most common joint diseases, there are no effective disease-modifying drugs, and the pathological mechanisms of OA need further investigation. Here, we show that H3K36 methylations were decreased in senescent chondrocytes and age-related osteoarthritic cartilage. Prrx1-Cre inducible H3.3K36M transgenic mice showed articular cartilage destruction and osteophyte formation. Conditional knockout Nsd1Prrx1-Cre mice, but not Nsd2Prrx1-Cre or Setd2Prrx1-Cre mice, replicated the phenotype of K36M/+; Prrx1-Cre mice. Immunostaining results showed decreased anabolic and increased catabolic activities in Nsd1Prrx1-Cre mice, along with decreased chondrogenic differentiation. Transcriptome and ChIP-seq data revealed that Osr2 was a key factor affected by Nsd1. Intra-articular delivery of Osr2 adenovirus effectively improved the homeostasis of articular cartilage in Nsd1Prrx1-Cre mice. In human osteoarthritic cartilages, both mRNA and protein levels of NSD1 and OSR2 were decreased. Our results indicate that NSD1-induced H3K36 methylations and OSR2 expression play important roles in articular cartilage homeostasis and OA. Targeting H3K36 methylation and OSR2 would be a novel strategy for OA treatment.

Profiling joint tissues at single-cell resolution: advances and insights

Advances in the profiling of human joint tissues at single-cell resolution have provided unique insights into the organization and function of these tissues in health and disease. Data generated by various single-cell technologies, including single-cell RNA sequencing and cytometry by time-of-flight, have identified the distinct subpopulations that constitute these tissues. These timely studies have provided the building blocks for the construction of single-cell atlases of joint tissues including cartilage, bone and synovium, leading to the identification of developmental trajectories, deciphering of crosstalk between cells and discovery of rare populations such as stem and progenitor cells. In addition, these studies have revealed unique pathogenetic populations that are potential therapeutic targets. The use of these approaches in synovial tissues has helped to identify how distinct cell subpopulations can orchestrate disease initiation and progression and be responsible for distinct pathological outcomes. Additionally, repair of tissues such as cartilage and meniscus remains an unmet medical need, and single-cell methodologies can be invaluable in providing a blueprint for both effective tissue-engineering strategies and therapeutic interventions for chronic joint diseases such as osteoarthritis and rheumatoid arthritis.

Aromatic Plants as Potential Resources to Combat Osteoarthritis

Osteoarthritis, which affects an estimated 10% of men and 18% of women over the age of 60 and is increasing in genetic prevalence and incidence, is acknowledged as the condition that degrades the quality of life for older adults in the world. There is currently no known treatment for osteoarthritis. The majority of therapeutic methods slow the progression of arthritis or treat its symptoms, making effective treatment to end the degenerative process of arthritis elusive. When non-pharmacological therapy is ineffective, various pharmacological therapies may be used to treat osteoarthritis. Pharmacological therapy, however, can have major adverse effects and be very expensive. As a result, alternative remedies have been researched. The promise for the safe and efficient management of osteoarthritis has been demonstrated by herbal remedies. Experimental research suggests that herbal extracts and compounds can reduce inflammation, inhibit catabolic processes, and promote anabolic processes that are important for treating osteoarthritis. Due to their therapeutic and innate pharmacological qualities, aromatic herbs are frequently employed as herbal remedies. Recent research has shown that aromatic plants have the potency to treat osteoarthritis. Additionally, complex mixtures of essential oils and their bioactive ingredients, which have anti-inflammatory and antioxidant properties and are obtained from aromatic plants, are frequently utilized as complementary therapies for osteoarthritis. To establish new study avenues, the advantageous anti-osteoarthritic effects of aromatic herbal medicines, including plants, essential oils, and their bioactive components, are extensively discussed.

Mechanism of Wenshen Xuanbi Decoction in the treatment of osteoarthritis based on network pharmacology and experimental verification

To investigate the mechanism of Wenshen Xuanbi Decoction (WSXB) in treating osteoarthritis (OA) via network pharmacology, bioinformatics analysis, and experimental verification. The active components and prediction targets of WSXB were obtained from the TCMSP database and Swiss Target Prediction website, respectively. OA-related genes were retrieved from GeneCards and OMIM databases. Protein-protein interaction and functional enrichment analyses were performed, resulting in the construction of the Herb-Component-Target network. In addition, differential genes of OA were obtained from the GEO database to verify the potential mechanism of WSXB in OA treatment. Subsequently, potential active components were subjected to molecular verification with the hub targets. Finally, we selected the most crucial hub targets and pathways for experimental verification in vitro. The active components in the study included quercetin, linolenic acid, methyl linoleate, isobergapten, and beta-sitosterol. AKT1, tumor necrosis factor (TNF), interleukin (IL)-6, GAPDH, and CTNNB1 were identified as the most crucial hub targets. Molecular docking revealed that the active components and hub targets exhibited strong binding energy. Experimental verification demonstrated that the mRNA and protein expression levels of IL-6, IL-17, and TNF in the WSXB group were lower than those in the KOA group (p < 0.05). WSXB exhibits a chondroprotective effect on OA and delays disease progression. The mechanism is potentially related to the suppression of IL-17 and TNF signaling pathways and the down-regulation of IL-6.

Daily low-intensity pulsed ultrasound stimulation mitigates joint degradation and pain in a post-traumatic osteoarthritis rat model

Objectives

The aim of this study was to investigate the effects of low-intensity pulsed ultrasound (LIPUS) in a post-traumatic osteoarthritis (OA) rat model and in vitro.

Methods

Thirty-eight male, four-month-old Sprague Dawley rats were randomly assigned to Sham, Sham ​+ ​US, OA, and OA ​+ ​US. Sham surgery was performed to serve as a negative control, and anterior cruciate ligament transection was used to induce OA. Three days after the surgical procedures, Sham ​+ ​US and OA ​+ ​US animals received daily LIPUS treatment, while the rest of the groups received sham ultrasound (US) signals. Behavioral pain tests were performed at baseline and every week thereafter. After 31 days, the tissues were collected, and histological analyses were performed on knees and innervated dorsal root ganglia (DRG) neurons traced by retrograde labeling. Furthermore, to assess the activation of osteoclasts by LIPUS treatment, RAW264.7 ​cells were differentiated into osteoclasts and treated with LIPUS.

Results

Joint degradation in cartilage and bone microarchitecture were mitigated in OA ​+ ​US compared to OA. OA ​+ ​US showed improvements in behavioral pain tests. A significant increase of large soma-sized DRG neurons was located in OA compared to Sham. In addition, a greater percentage of large soma-sized innervated neurons were calcitonin gene-related peptide-positive. Daily LIPUS treatment suppressed osteoclastogenesis in vitro, which was confirmed via histological analyses and mRNA expression. Finally, lower expression of netrin-1, a sensory innervation-related protein, was found in the LIPUS treated cells.

Conclusion

Our findings demonstrate that early intervention using LIPUS treatment has protective effects from the progression of knee OA, including reduced tissue degradation, mitigated pain characteristics, improved subchondral bone microarchitecture, and less sensory innervation. Furthermore, daily LIPUS treatment has a suppressive effect on osteoclastogenesis, which may be linked to the suppression of sensory innervation in OA.

The translational potential of this article

This study presents a new potential for early intervention in treating OA symptoms through the use of LIPUS, which involves the suppression of osteoclastogenesis and the alteration of DRG profiles. This intervention aims to delay joint degradation and reduce pain.

Bioinformatics analysis of hub genes as osteoarthritis prognostic biomarkers

Osteoarthritis (OA) is a progressive cartilage degradation disease, concomitant with synovitis, osteophyte formation, and subchondral bone sclerosis. Over 37% of the elderly population is affected by OA, and the number of cases is increasing as the global population ages. Therefore, the objective of this study was to identify and analyze the hub genes of OA combining with comprehensive bioinformatics analysis tools to provide theoretical basis in further OA effective therapies. Two sample sets of GSE46750 contained 12 pairs OA synovial membrane and normal samples harvested from patients as well as GSE98918 including 12 OA and non-OA patients were downloaded from the Gene Expression Omnibus database (GEO) database. Differentially expressed genes (DEGs) were identified using Gene Expression Omnibus 2R (GEO2R), followed by functional enrichment analysis, protein-protein interaction networks construction. The hub genes were identified and evaluated. An OA rat model was constructed, hematoxylin and eosin staining, safranin O/fast green staining, cytokines concentrations of serum were used to verify the model. The hub genes expression level in the knee OA samples were verified using RT-qPCR. The top 20 significantly up-regulated and down-regulated DEGs were screened out from the two datasets, respectively. The top 18 GO terms and 10 KEGG pathways were enriched. Eight hub genes were identified, namely MS4A6A, C1QB, C1QC, CD74, CSF1R, HLA-DPA1, HLA-DRA and ITGB2. Among them, the hub genes were all up-regulated in in vivo OA rat model, compared with healthy controls. The eight hub genes identified (MS4A6A, C1QB, C1QC, CD74, CSF1R, HLA-DPA1, HLA-DRA and ITGB2) were shown to be associated with OA. These genes can serve as disease markers to discriminate OA patients from healthy controls.

Tanshinone IIA Facilitates Efficient Cartilage Regeneration under Inflammatory Factors Caused Stress via Upregulating LncRNA NEAT1_2

(1) Background: Osteoarthritis (OA) is a crippling condition characterized by chondrocyte dedifferentiation, cartilage degradation, and subsequent cartilage defects. Unfortunately, there is a lack of effective medicines to facilitate the repair of cartilage defects in OA patients. In this study, we investigated the role of lncRNA NEAT1_2 in maintaining the chondrocyte phenotype and identified tanshinone IIA(TAN) as a natural medicine that enhances NEAT1_2 levels, resulting in efficient cartilage regeneration under inflammatory cytokines. (2) Methods: The transcriptional levels of NEAT1_2 and cartilage phenotype-related genes were identified by RT-qPCR. The siRNA interference approach was utilized to silence NEAT1_2; the Alamar Blue assay was performed to determine chondrocyte viability under inflammatory conditions. To evaluate the concentrations of collagen type II and glycosaminoglycans distributed by chondrocytes in vitro and in vivo, immunohistochemical staining and Safranin O staining were used. (3) Results: IL-1β suppresses NEAT1_2 and genes related to the chondrocytic phenotype, whereas TAN effectively upregulates them in a NEAT1_2-dependent manner. Consistently, TAN alleviated chondrocyte oxidative stress inhibited cartilage degradation by modulating the relevant genes and promoted efficient cartilage regeneration in vitro and in vivo when chondrocytes are exposed to inflammatory cytokines. (4) Conclusions: TAN enhances the expression of NEAT1_2 inhibited by IL-1β and affects the transcription of chondrocytic phenotype-related genes, which promotes cartilage regeneration in an inflammatory environment.

Prokineticin 2 is a catabolic regulator of osteoarthritic cartilage destruction in mouse

BACKGROUND

Our preliminary study indicates that the multi-functional protein, prokineticin 2 (Prok2), is upregulated in osteoarthritic (OA) chondrocytes as a target of the hypoxia-inducible factor (HIF)-2α. This study aims to elucidate the potential roles of Prok2 in OA.

METHODS

Prok2 expression was assessed through microarray analysis in chondrocytes and confirmed via immunostaining in OA cartilage. Experimental OA was induced through destabilization of the medial meniscus (DMM). Functions of Prok2 were assessed by adenoviral overexpression, intra-articular (IA) injection of recombinant Prok2 (rProk2), and knockdown of Prok2 in joint tissues. We also explored the potential utility of Prok2 as an OA biomarker using enzyme-linked immunosorbent assay (ELISA).

RESULTS

HIF-2α upregulated Prok2, one of the prokineticin signaling components, in OA chondrocytes of mice and humans. Adenoviral overexpression of Prok2 in chondrocytes and cartilage explants, as well as the application of rProk2, led to an upregulation of matrix metalloproteinase (MMP)3 and MMP13. Consistently, the overexpression of Prok2 in joint tissues or IA injection of rProk2 exacerbated cartilage destruction and hindpaw mechanical allodynia induced by DMM. However, the knockdown of Prok2 in joint tissues did not significantly affect DMM-induced cartilage destruction. Additionally, despite being a secreted protein, the serum levels of Prok2 in OA mice and human OA patients were found to be below the range detected by ELISA.

CONCLUSION

The upregulation of Prok2 exacerbates OA cartilage destruction and hindpaw mechanical allodynia. However, its knockdown is not sufficient to inhibit experimental OA and Prok2 is not a potential candidate serum biomarker of OA.

Risk of metabolic abnormalities in osteoarthritis: a new perspective to understand its pathological mechanisms

Although aging has traditionally been viewed as the most important risk factor for osteoarthritis (OA), an increasing amount of epidemiological evidence has highlighted the association between metabolic abnormalities and OA, particularly in younger individuals. Metabolic abnormalities, such as obesity and type II diabetes, are strongly linked to OA, and they affect both weight-bearing and non-weight-bearing joints, thus suggesting that the pathogenesis of OA is more complicated than the mechanical stress induced by overweight. This review aims to explore the recent advances in research on the relationship between metabolic abnormalities and OA risk, including the impact of abnormal glucose and lipid metabolism, the potential pathogenesis and targeted therapeutic strategies.

Expanding the therapeutic potential of Salvia miltiorrhiza: a review of its pharmacological applications in musculoskeletal diseases

Salvia miltiorrhiz, commonly known as "Danshen" in Chinese medicine, has longstanding history of application in cardiovascular and cerebrovascular diseases. Renowned for its diverse therapeutic properties, including promoting blood circulation, removing blood stasis, calming the mind, tonifying the blood, and benefiting the "Qi", recent studies have revealed its significant positive effects on bone metabolism. This potential has garnered attention for its promising role in treating musculoskeletal disorders. Consequently, there is a high anticipation for a comprehensive review of the potential of Salvia miltiorrhiza in the treatment of various musculoskeletal diseases, effectively introducing an established traditional Chinese medicine into a burgeoning field.

AIM OF THE REVIEW

Musculoskeletal diseases (MSDs) present significant challenges to healthcare systems worldwide. Previous studies have demonstrated the high efficacy and prospects of Salvia miltiorrhiza and its active ingredients for treatment of MSDs. This review aims to illuminate the newfound applications of Salvia miltiorrhiza and its active ingredients in the treatment of various MSDs, effectively bridging the gap between an established medicine and an emerging field.

METHODS

In this review, previous studies related to Salvia miltiorrhiza and its active ingredients on the treatment of MSD were collected, the specific active ingredients of Salvia miltiorrhiza were summarized, the effects of Salvia miltiorrhiza and its active ingredients for the treatment of MSDs, as well as their potential molecular mechanisms were reviewed and discussed.

RESULTS

Based on previous publications, Salvianolic acid A, salvianolic acid B, tanshinone IIA are the representative active ingredients of Salvia miltiorrhiza. Their application has shown significant beneficial outcomes in osteoporosis, fractures, and arthritis. Salvia miltiorrhiza and its active ingredients protect against MSDs by regulating different signaling pathways, including ROS, Wnt, MAPK, and NF-κB signaling.

CONCLUSION

Salvia miltiorrhiza and its active ingredients demonstrate promising potential for bone diseases and have been explored across a wide variety of MSDs. Further exploration of Salvia miltiorrhiza's pharmacological applications in MSDs holds great promise for advancing therapeutic interventions and improving the lives of patients suffering from these diseases.

CD19, ALDH18A1, and CACNA1G as Significant Hub Genes in End-Stage Osteoarthritis

Background

Osteoarthritis is one of the principal causes of chronic joint disease and may progressively engender disability in elderly individuals. The present study aimed to identify differentially expressed genes and associated signaling pathways in end-stage osteoarthritis.

Methods

Differentially expressed messenger RNAs in the early and end stages of osteoarthritis were examined through gene expression omnibus 2R (GEO2R) in the GSE32317 dataset. Subsequently, gene ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG), and protein-protein interaction (PPI) analyses were conducted. Furthermore, microRNAs targeting hub genes were investigated using the miRcode database. This study was conducted jointly at Bam University of Medical Sciences and Rajaie Cardiovascular, Medical and Research Center on October 2022.

Results

Differentially expressed data demonstrated downregulation in 134 genes and upregulation in 189 genes in end-stage knee osteoarthritis. The results of the enrichment and PPI analyses determined 4 end-stage knee osteoarthritis-related hub genes: IL-1B, CD19, CACNA1G, and ALDH18A1. The knee osteoarthritis-related key genes were involved in the Wnt signaling, B cell receptor signaling, calcium signaling, circadian entrainment, arginine and proline metabolism, axon guidance, and cytokine-cytokine receptor pathways. Additionally, the microRNAs targeting the 4 aforementioned genes were predicted.

Conclusion

The present study is the first to provide fresh insights into the potential therapeutic targets of key genes, namely CD19, CACNA1G, and ALDH18A1, differentially expressed in end-stage osteoarthritis and their relevant signaling pathways and interactive microRNAs.

A robust NIR fluorescence-activated probe for peroxynitrite imaging in cells and mice osteoarthritis models

Osteoarthritis (OA) is the most common type of joint disease, which is difficult to treat, but early standardized diagnosis and treatment can effectively alleviate the pain and symptoms of patients. Therefore, it is important to construct an effective tool to assist in the early diagnosis and evaluation of the therapeutic effect of OA. In this work, a near-infrared (NIR) fluorescence-activated fluorescent probe, YB-1, was constructed for the evaluation of the diagnostic and therapeutic efficacy of OA via detection and imaging of the biomarker of ONOO- in inflammatory cells and mice osteoarthritis models. YB-1 exhibited high selectivity, high sensitivity, and a high ratio yield (I668/I0) fluorescence increasing (∼30 folds). Besides, YB-1 can be used effectively to image endogenous and exogenous ONOO- in living human chondrocytes cells (TC28a2), as well as to evaluate the effect of drug (Chrysosplenol D, CD) treatment in IL-1β-induced inflammatory cells model. Interestingly, YB-1 was available for OONO- imaging analysis in the collagenase-induced mice OA models and assessment of the effect of CD treatment in mice OA models, with good results. Thus, the newly constructed YB-1 is a powerful molecular tool for the diagnosis and treatment of OA-related diseases.

Single-cell RNA sequencing in osteoarthritis

Osteoarthritis is a progressive and heterogeneous joint disease with complex pathogenesis. The various phenotypes associated with each patient suggest that better subgrouping of tissues associated with genotypes in different phases of osteoarthritis may provide new insights into the onset and progression of the disease. Recently, single-cell RNA sequencing was used to describe osteoarthritis pathogenesis on a high-resolution view surpassing traditional technologies. Herein, this review summarizes the microstructural changes in articular cartilage, meniscus, synovium and subchondral bone that are mainly due to crosstalk amongst chondrocytes, osteoblasts, fibroblasts and endothelial cells during osteoarthritis progression. Next, we focus on the promising targets discovered by single-cell RNA sequencing and its potential applications in target drugs and tissue engineering. Additionally, the limited amount of research on the evaluation of bone-related biomaterials is reviewed. Based on the pre-clinical findings, we elaborate on the potential clinical values of single-cell RNA sequencing for the therapeutic strategies of osteoarthritis. Finally, a perspective on the future development of patient-centred medicine for osteoarthritis therapy combining other single-cell multi-omics technologies is discussed. This review will provide new insights into osteoarthritis pathogenesis on a cellular level and the field of applications of single-cell RNA sequencing in personalized therapeutics for osteoarthritis in the future.

A Review of the Role of Bioreactors for iPSCs-Based Tissue-Engineered Articular Cartilage

BACKGROUND

Osteoarthritis (OA) is the most common degenerative joint disease without an ultimate treatment. In a search for novel approaches, tissue engineering (TE) has shown great potential to be an effective way for hyaline cartilage regeneration and repair in advanced stages of OA. Recently, induced pluripotent stem cells (iPSCs) have been appointed to be essential stem cells for degenerative disease treatment because they allow a personalized medicine approach. For clinical translation, bioreactors in combination with iPSCs-engineerd cartilage could match patients needs, serve as platform for large-scale patient specific cartilage production, and be a tool for patient OA modelling and drug screening. Furthermore, to minimize in vivo experiments and improve cell differentiation and cartilage extracellular matrix (ECM) deposition, TE combines existing approaches with bioreactors.

METHODS

This review summarizes the current understanding of bioreactors and the necessary parameters when they are intended for cartilage TE, focusing on the potential use of iPSCs.

RESULTS

Bioreactors intended for cartilage TE must resemble the joint cavity niche. However, recreating human synovial joints is not trivial because the interactions between various stimuli are not entirely understood.

CONCLUSION

The use of mechanical and electrical stimulation to differentiate iPSCs, and maintain and test chondrocytes are key stimuli influencing hyaline cartilage homeostasis. Incorporating these stimuli to bioreactors can positively impact cartilage TE approaches and their possibility for posterior translation into the clinics.

Systematic review and meta-analysis of economic and healthcare resource utilization outcomes for robotic versus manual total knee arthroplasty

The introduction of robotics in orthopedic surgery has led to improved precision and standardization in total knee arthroplasty (TKA). Clinical benefits of robotic versus manual TKA have been well established; however, evidence for economic and healthcare resource utilization outcomes (HRU) is lacking. The primary objective of this study was to compare economic and HRU outcomes for robotic and manual TKA. The secondary objective was to explore comparative robotic and manual TKA pain and opioid consumption outcomes. Multi-database literature searches were performed to identify studies comparing robotic and manual TKA from 2016 to 2022 and meta-analyses were conducted. This review included 50 studies with meta-analyses conducted on 35. Compared with manual TKA, robotic TKA was associated with a: 14% reduction in hospital length of stay (P = 0.022); 74% greater likelihood to be discharged to home (P < 0.001); and 17% lower likelihood to experience a 90-day readmission (P = 0.043). Robotic TKA was associated with longer mean operating times (incision to closure definition: 9.27 min longer, P = 0.030; general operating time definition: 18.05 min longer, P = 0.006). No differences were observed for total procedure cost and 90-day emergency room visits. Most studies reported similar outcomes for robotic and manual TKA regarding pain and opioid use. Coupled with the clinical benefits of robotic TKA, the economic impact of using robotics may contribute to hospitals' quality improvement and financial sustainability. Further research and more randomized controlled trials are needed to effectively quantify the benefits of robotic relative to manual TKA.

Inhibition of LncRNA SNHG14 protects chondrocyte from injury in osteoarthritis via sponging miR-137

Long-chain noncoding small nucleolar RNA host gene 14 (LncRNA SNHG14) is highly expressed in various diseases and promotes diseases progression, but the role and mechanism of LncRNA SNHG14 on targeting miR-137 in promoting osteoarthritis (OA) chondrocyte injury remains unclear. To measure the expression of the LncRNAs SNHG14 and miR-137, cell survival, inflammatory response, chondrocyte apoptosis, and extracellular matrix (ECM) levels, we subjected human chondrocytes to a variety of lipopolysaccharide (LPS) concentrations. To measure the luciferase activity of SNHG14-WT and SNHG14-MUT transfected with miR-137 mimic or miR-NC mimic, luciferase reporter genes were utilized. The results showed that chondrocyte viability was significantly inhibited with LPS treatment and chondrocyte inflammatory response, apoptosis and extracellular matrix degradation were significantly increased. However, the above results were significantly reversed after LncRNA SNHG14 inhibition. The luciferase activity bound to miR-137 was decreased in SNHG14-WT group, but there was no change in SNHG14-mut group, which indicated that LncRNA SNHG14 inhibited miR-137 expression as a miRNA sponge. In conclusion, inhibition of LncRNA SNHG14 attenuates chondrocyte inflammatory response, apoptosis and extracellular matrix degradation by targeting miR-137 in LPS induced chondrocytes.

Sarsasapogenin inhibits YAP1-dependent chondrocyte ferroptosis to alleviate osteoarthritis

The involvement of chondrocyte ferroptosis in the development of osteoarthritis (OA) has been observed, and Sarsasapogenin (Sar) has therapeutic promise in a variety of inflammatory diseases. This study investigates the potential influence of Sar on the mechanism of chondrocyte ferroptotic cell death in the progression of osteoarthritic cartilage degradation. An in vivo medial meniscus destabilization (DMM)-induced OA animal model as well as an in vitro examination of chondrocytes in an OA microenvironment induced by interleukin-1β (IL-1β) exposure were employed. Histology, immunofluorescence, quantitative RT-PCR, Western blot, cell viability, and Micro-CT analysis were utilized in conjunction with gene overexpression and knockdown to evaluate the chondroprotective effects of Sar in OA progression and the role of Yes-associated protein 1 (YAP1) in Sar-induced ferroptosis resistance of chondrocytes. In this study we found Sar reduced chondrocyte ferroptosis and OA progression. And Sar-induced chondrocyte ferroptosis resistance was mediated by YAP1. Furthermore, infection of siRNA specific to YAP1 in chondrocytes reduced Sar's chondroprotective and ferroptosis-suppressing effects during OA development. The findings suggest that Sar mitigates the progression of osteoarthritis by decreasing the sensitivity of chondrocytes to ferroptosis through the promotion of YAP1, indicating that Sar has the potential to serve as a therapeutic approach for diseases associated with ferroptosis.

Identification of Novel Diagnostic Biomarkers and Classification Patterns for Osteoarthritis by Analyzing a Specific Set of Genes Related to Inflammation

Osteoarthritis (OA) is a prevalent joint disease globally. TNFA is recognized as a crucial inflammatory cytokine that plays a significant role in the pathophysiological mechanisms that occur during the progression of OA. However, the TNFA_SIGNALING_VIA_NFKB (TSVN)-related genes (TRGs) during the progression of OA remain unclear. By conducting a combinatory analysis of OA transcriptome data from three datasets, various differentially expressed TRGs were identified. The logistic regression model was used to mine hub TRGs for OA, and a nomogram prediction model was subsequently constructed using these TRGs. To identify new molecular subgroups, we performed consensus clustering. We then conducted functional analyses, including GO, KEGG, GSVA, and GSEA, to elucidate the underlying mechanisms. To determine the immune microenvironment, we applied xCell. The logistic regression analysis identified three hub TRGs (BHLHE40, BTG2, and CCNL1) as potential biomarkers for OA. Based on these TRGs, we constructed an OA predictive model. This model has demonstrated promising results in enhancing the accuracy of OA diagnosis, as evident from the ROC analysis (AUC merged dataset = 0.937, AUC validating dataset = 0.924). We identified two molecular subtypes, C1 and C2, and found that the C1 subtype showed activation of immune- and inflammation-related pathways. The involvement of TSVN in the development and progression of OA has been established. We identified several hub genes, such as BHLHE40, BTG2, and CCNL1, that may have a significant association with the progression of OA. Furthermore, our logistic regression model based on these genes has shown promising results in accurately diagnosing OA patients.

The Risk Factors and Preventive Strategies of Poor Knee Functions and Osteoarthritis after Anterior Cruciate Ligament Reconstruction: A Narrative Review

Anterior cruciate ligament reconstruction (ACLR) is the standard surgical treatment for ACL injury, which typically uses a graft to replace the torn ligament in the knee that uses small incisions with minimally invasive surgery. The optimal knee functions following ACLR depend on rehabilitation processes before and after the surgery. Knee function is the ability of the knee to perform various types of functional movements like walking, squatting, running, jumping, and pivoting where patients expect to achieve maximum knee function or at least more than 80% of its initial condition before the injury to avoid being categorized as poor knee function after ACLR. Patients use patient-reported outcome measures to collect data on their health status and quality of life after ACLR. Post-traumatic osteoarthritis (PTOA) is a type of OA that manifests in local cartilage injury caused by chondrocyte death, and matrix dispersion occurs following a joint injury like ACL injury. Gender, time from injury to surgery, and graft type were considered as risk factors for poor knee function after ACLR, while overweight, meniscus tear, and cartilage defect as risk factors for PTOA. However, age is an internal risk factor for both poor knee function and PTOA following ACLR. This review suggests several strategies to prevent both conditions, including a pre-operative program, comprehensive rehabilitation, body weight control, and return to sport (RTS) consideration based on physical capacity, proper time, and psychological readiness.

A Reproducible Cartilage Impact Model to Generate Post-Traumatic Osteoarthritis in the Rabbit

Post-traumatic osteoarthritis (PTOA) is responsible for 12% of all osteoarthritis cases in the United States. PTOA can be initiated by a single traumatic event, such as a high-impact load acting on articular cartilage, or by joint instability, as occurs with anterior cruciate ligament rupture. There are no effective therapeutics to prevent PTOA currently. Developing a reliable animal model of PTOA is necessary to better understand the mechanisms by which cartilage damage proceeds and to investigate novel treatment strategies to alleviate or prevent the progression of PTOA. This protocol describes an open, drop tower-based rabbit femoral condyle impact model to induce cartilage damage. This model delivered peak loads of 579.1 ± 71.1 N, and peak stresses of 81.9 ± 10.1 MPa with a time-to-peak load of 2.4 ± 0.5 ms. Articular cartilage from impacted medial femoral condyles (MFCs) had higher rates of apoptotic cells (p = 0.0058) and possessed higher Osteoarthritis Research Society International (OARSI) scores of 3.38 ± 1.43 compared to the non-impacted contralateral MFCs (0.56 ± 0.42), and other cartilage surfaces of the impacted knee (p < 0.0001). No differences in OARSI scores were detected among the non-impacted articular surfaces (p > 0.05).

Inflammatory and Metabolic Signaling Interfaces of the Hypertrophic and Senescent Chondrocyte Phenotypes Associated with Osteoarthritis

Osteoarthritis (OA) is a complex disease of whole joints with progressive cartilage matrix degradation and chondrocyte transformation. The inflammatory features of OA are reflected in increased synovial levels of IL-1β, IL-6 and VEGF, higher levels of TLR-4 binding plasma proteins and increased expression of IL-15, IL-18, IL-10 and Cox2, in cartilage. Chondrocytes in OA undergo hypertrophic and senescent transition; in these states, the expression of Sox-9, Acan and Col2a1 is suppressed, whereas the expression of RunX2, HIF-2α and MMP-13 is significantly increased. NF-kB, which triggers many pro-inflammatory cytokines, works with BMP, Wnt and HIF-2α to link hypertrophy and inflammation. Altered carbohydrate metabolism and the upregulation of GLUT-1 contribute to the formation of end-glycation products that trigger inflammation via the RAGE pathway. In addition, a glycolytic shift, increased rates of oxidative phosphorylation and mitochondrial dysfunction generate reactive oxygen species with deleterious effects. An important surveyor mechanism, the YAP/TAZ signaling system, controls chondrocyte differentiation, inhibits ageing by protecting the nuclear envelope and suppressing NF-kB, MMP-13 and aggrecanases. The inflammatory microenvironment and synthesis of key matrix components are also controlled by SIRT1 and mTORc. Senescent chondrocytes represent the functional end stage of hypertrophic differentiation and characteristically upregulate p16 and p21, but also a variety of inflammatory cytokines, chemokines and metalloproteinases, developing the senescence-associated secretory phenotype. Senolysis with dendrobin, miR29b-5p and other agents has been shown to be efficient under experimental conditions, and appears to be a promising tool for the treatment of OA, as it restores COL2A1 and aggrecan synthesis, suppressing NF-kB and destructive metalloproteinases.

Plasma-derived extracellular vesicle surface markers CD45, CD326 and CD56 correlate with the stage of osteoarthritis: a primary study of a novel and promising diagnostic tool of the disease

Recently, there is a growing interest in the research based on extracellular vesicles (EVs) which represent paracrine factors secreted by almost all cell types. Both, normal and pathological cells are able to release various types of EVs with different physiological properties, functions and compositions. EVs play an important role in intercellular communication, mechanism and tissue repair. Moreover, EVs could help not only in the treatment of diseases but also in their diagnostics. This work focused on the evaluation of the potential of EVs being used as biomarkers for the diagnosis of osteoarthritis (OA) based on a comparison of the composition of EVs separated from platelet-poor plasma (PPP) of healthy donors and OA patients at different stages of OA. OA is established as a complex syndrome with extensive impact on multiple tissues within the synovial joint. It is a chronic disease of musculoskeletal system that mainly affects the elderly. Depending on the use of the Kellgren-Lawrence classification system, there are four grades of OA which have a negative impact on patients' quality of life. It is very difficult to detect OA in its early stages, so it is necessary to find a new diagnostic method for its timely detection. PPP samples were prepared from whole blood. PPP-EVs were separated from 3 groups of donors-healthy control, early stage OA, end-stage OA, and their content was compared and correlated. EVs from PPP were separated by size exclusion chromatography and characterized in terms of their size, yield and purity by NTA, western blotting, ELISA and flow cytometry. Detection of surface markers expression in EVs was performed using MACSPlex approach. Inflammatory and growth factors in EVs were analysed using MAGPix technology. Our study confirmed significant differences between EVs surface markers of patients and healthy controls correlating with the age of donor (CD63, CD31 and ROR1) and stage of OA (CD45, CD326 and CD56), respectively. Circulating EVs have been under extensive investigation for their capability to predict OA pathology diagnosis as potential targets for biomarker discovery. Taken together, obtained results indicated that PPP-EVs surface markers could be used as potential biomarkers in the early diagnosis of OA.

Face and Predictive Validity of MI-RAT (Montreal Induction of Rat Arthritis Testing), a Surgical Model of Osteoarthritis Pain in Rodents Combined with Calibrated Exercise

Validating animal pain models is crucial to enhancing translational research and response to pharmacological treatment. This study investigated the effects of a calibrated slight exercise protocol alone or combined with multimodal analgesia on sensory sensitivity, neuroproteomics, and joint structural components in the MI-RAT model. Joint instability was induced surgically on day (D) 0 in female rats (N = 48) distributed into sedentary-placebo, exercise-placebo, sedentary-positive analgesic (PA), and exercise-PA groups. Daily analgesic treatment (D3-D56) included pregabalin and carprofen. Quantitative sensory testing was achieved temporally (D-1, D7, D21, D56), while cartilage alteration (modified Mankin's score (mMs)) and targeted spinal pain neuropeptide were quantified upon sacrifice. Compared with the sedentary-placebo (presenting allodynia from D7), the exercise-placebo group showed an increase in sensitivity threshold (p < 0.04 on D7, D21, and D56). PA treatment was efficient on D56 (p = 0.001) and presented a synergic anti-allodynic effect with exercise from D21 to D56 (p < 0.0001). Histological assessment demonstrated a detrimental influence of exercise (mMs = 33.3%) compared with sedentary counterparts (mMs = 12.0%; p < 0.001), with more mature transformations. Spinal neuropeptide concentration was correlated with sensory sensitization and modulation sites (inflammation and endogenous inhibitory control) of the forced mobility effect. The surgical MI-RAT OA model coupled with calibrated slight exercise demonstrated face and predictive validity, an assurance of higher clinical translatability.

BMP signaling: A significant player and therapeutic target for osteoarthritis

OBJECTIVE

To explore the significance of BMP signaling in osteoarthritis (OA) etiology, and thereafter propose a disease-modifying therapy for OA.

METHODS

To examine the role of the BMP signaling in pathogenesis of OA, an Anterior Cruciate Ligament Transection (ACLT) surgery was performed to incite OA in C57BL/6J mouse line at postnatal day 120 (P120). Thereafter, to investigate whether activation of BMP signaling is necessary and sufficient to induce OA, we have used conditional gain- and loss-of-function mouse lines in which BMP signaling can be activated or depleted, respectively, upon intraperitoneal injection of tamoxifen. Finally, we locally inhibited BMP signaling through intra-articular injection of LDN-193189 pre- and post-onset surgically induced OA. The majority of the investigation has been conducted using micro-CT, histological staining, and immuno histochemistry to assess the disease etiology.

RESULTS

Upon induction of OA, depletion of SMURF1-an intra-cellular BMP signaling inhibitor in articular cartilage coincided with the activation of BMP signaling, as measured by pSMAD1/5/9 expression. In mouse articular cartilage, the BMP gain-of-function mutation is sufficient to induce OA even without surgery. Further, genetic, or pharmacological BMP signaling suppression also prevented pathogenesis of OA. Interestingly, inflammatory indicators were also significantly reduced upon LDN-193189 intra-articular injection which inhibited BMP signaling and slowed OA progression post onset.

CONCLUSION

Our findings showed that BMP signaling is crucial to the etiology of OA and inhibiting BMP signaling locally can be a potent strategy for alleviating OA.

Kukoamine A protects mice against osteoarthritis by inhibiting chondrocyte inflammation and ferroptosis via SIRT1/GPX4 signaling pathway

AIMS

Osteoarthritis (OA) is one of the common chronic degenerative joint diseases, characterized by cartilage damage, subchondral bone changes, osteophyte formation, and synovitis. Kukoamine A (KuKA) is a bioactive compound isolated from Lycium chinense which is known as its anti-inflammatory activity. In this study, we detected the regulatory role of KuKA on OA both in vivo and in vitro.

MATERIALS AND METHODS

Mouse chondrocytes were cultured and mouse model of OA was established. Inflammatory mediator was measured by ELISA. The signaling pathway was tested by western blot analysis.

KEY FINDINGS

KuKA inhibited IL-1β-induced PGE2 and NO production and iNOS and COX-2 expression. IL-1β-induced MMP1 and MMP3 production was attenuated by KuKA. IL-1β-induced MDA, iron, and ROS were alleviated by KuKA. Meanwhile, GSH content, GPX4, Ferritin, SIRT1, Nrf2, and HO-1 expression were upregulated by KuKA. Furthermore, the inhibitory role of KuKA on IL-1β-induced inflammation, MMPs production, and ferroptosis were reversed by SIRT1 inhibitor. In vivo, KuKA could attenuate OA development in mouse model. KuKA markedly alleviated MMP1, MMP3, iNOS, and COX2 expression in OA mice.

SIGNIFICANCE

In conclusion, KuKA could inhibit OA development through suppressing chondrocyte inflammation and ferroptosis via SIRT1/GPX4 signaling pathway.

Surface-Modified Nano-Hydroxyapatite Uniformly Dispersed on High-Porous GelMA Scaffold Surfaces for Enhanced Osteochondral Regeneration

Purpose

This study aims to investigate the impact of enhancing subchondral bone repair on the efficacy of articular cartilage restoration, thereby achieving improved osteochondral regeneration outcomes.

Methods

In this study, we modified the surface of nano-hydroxyapatite (n-HAp) through alkylation reactions to prepare n-HApMA. Characterization techniques, including X-ray diffraction, infrared spectroscopy scanning, thermogravimetric analysis, particle size analysis, and electron microscopy, were employed to analyze n-HApMA. Bioinks were prepared using n-HApMA, high porosity GelMA hydrogel, and adipose tissue derived stromal cells (ADSCs). The rheological properties of the bioinks during photocuring were investigated using a rheometer. Based on these bioinks, a biphasic scaffold was constructed. The viability of cells within the scaffold was observed using live-dead cell staining, while the internal morphology was examined using scanning electron microscopy. The stiffness of the scaffold was evaluated through compression testing. Scaffolds were implanted into the osteochondral defects of New Zealand rabbit knees, and microCT was utilized to observe the subchondral bone repair. Hematoxylin and eosin (H&E) staining, Masson's trichrome staining, and Safranin O/Fast Green staining were performed to assess the regeneration of subchondral bone and cartilage. Furthermore, immunohistochemical staining was employed to detect the expression of osteogenic and chondrogenic-related molecules.

Results

Scaffold characterization revealed that surface modification enables the uniform distribution of n-HApMA within the GelMA matrix. The incorporation of 5% n-HApMA notably enhanced the elastic modulus and stiffness of the 6% high-porosity GelMA in comparison to n-HAp. Moreover, in-vivo study showed that the homogeneous dispersion of n-HApMA on the GelMA matrix facilitated the osteogenic differentiation of adipose-derived stem cells (ADSCs) and promoted osteochondral tissue regeneration.

Conclusion

These findings suggest potential applications of the n-HApMA/GelMA composite in the field of tissue engineering and regenerative medicine.

Integrated single-cell and bulk RNA sequencing analysis identified pyroptosis-related signature for diagnosis and prognosis in osteoarthritis

Osteoarthritis (OA), a degenerative disease of the joints, has one of the highest disability rates worldwide. This study investigates the role of pyroptosis-related genes in osteoarthritis and their expression in different chondrocyte subtypes at the individual cell level. Using OA-related datasets for single-cell RNA sequencing and RNA-seq, the study identified PRDEGs and DEGs and conducted Cox regression analysis to identify independent prognostic factors for OA. CASP6, NOD1, and PYCARD were found to be prognostic factors. Combined Weighted Gene Correlation Network Analysis with PPI network, a total of 15 hub genes related to pyroptosis were involved in the notch and oxidative phosphorylation pathways, which could serve as biomarkers for the diagnosis and prognosis of OA patients. The study also explored the heterogeneity of chondrocytes between OA and normal samples, identifying 19 single-cell subpopulation marker genes that were significantly different among 7 chondrocyte cell clusters. AGT, CTSD, CYBC, and THYS1 were expressed differentially among different cell subpopulations, which were associated with cartilage development and metabolism. These findings provide valuable insights into the molecular mechanisms underlying OA and could facilitate the development of new therapeutic strategies for this debilitating disease.

The Role of Nutrition in Osteoarthritis Development

Osteoarthritis (OA) prevalence has increased 113% since 1990, and currently more than half a billion people worldwide are living with this slowly progressing, degenerative joint disease [...].

Single-cell RNA sequencing reveals neurovascular-osteochondral network crosstalk during temporomandibular joint osteoarthritis: Pilot study in a human condylar cartilage

Purpose

Temporomandibular joint osteoarthritis (TMJ-OA) is one of the most complex temporomandibular disorders, causing pain and dysfunction. The main pathological feature of TMJ-OA is neurovascular invasion from the subchondral bone to the condylar cartilage. This study aimed to discover the cells and genes that play an important role in the neurovascular-osteochondral network crosstalk in human TMJ-OA.

Materials and methods

Condylar cartilages from patient with TMJ-OA were divided into OA group, and others from patients with benign condylar hyperplasia (CH) were used as control for further single-cell RNA-sequencing (scRNA-seq). Hematoxylin and eosin staining were performed. The cells and genes in the condylar cartilage were identified and analyzed by scRNA-seq.

Results

Histological analysis revealed blood vessel invasion and ossification in the TMJ-OA condylar cartilage. The scRNA-seq identified immune cells, endothelial cells, and chondrocytes in the TMJ-OA condylar cartilage. Macrophages, especially M1-like macrophages, contributed to the inflammation, angiogenesis, and innervation. CD31+ endothelial cells contributed to the bone mineralization. The TMJ-OA cartilage chondrocytes highly expressed genes related to inflammation, angiogenesis, innervation, and ossification. The hub genes contributing to these processes in the TMJ-OA chondrocytes included CTGF, FBN1, FN1, EGFR, and ITGA5.

Conclusion

Our study marks the first time scRNA-seq was used to identify the cells and genes in a human TMJ-OA condylar cartilage, and neurovascular-osteochondral network crosstalk during the human TMJ-OA process was demonstrated. Targeting the crosstalk of these processes may be a potential comprehensive and effective therapeutic strategy for human TMJ-OA.

Multivariate assessments of activity-related skeletal changes: Interpreting Bell Beaker specialized male archery and social organization in Central Europe

OBJECTIVES

The Bell Beaker period witnessed the rise of individual inhumations with "wealthy" burial contexts containing archery-related grave goods, leading archaeologists to label the individuals in these tombs as "archers." This study looks to (1) compare the skeletons from male "archer" burials with those from male "non-archer" burials-those not having archery-related grave goods-in order to assess a possible link between burial context and physical activity, and (2) apply a biomechanics profile to evaluate whether the individuals associated with these "archer" burials practiced specialized archer activity.

MATERIALS AND METHODS

The corpus (males only) included 46 "archers" and 40 "non-archers" from Bell Beaker individual inhumations. Osteological data included measurements, scores of entheseal changes, and a diagnosis of certain pathologies. Data analyses involved visual observations, hypothesis tests, dimension reduction, and MANOVA, with approaches aimed at exploring the treatment of data missingness.

RESULTS

Measurement data revealed no differences between the two groups. Evaluations of entheseal changes found that "non-archers" had consistently more instances of bone surface modifications than "archers." Individual assessments of specialized archer occupation identified 11 possible specialized archers.

DISCUSSION

These findings indicate a possible labor differentiation represented through the presence of a probably prestigious "archer" burial context. This suggests a link between grave good presence and labor, but not between a Bell Beaker archery occupation and an "archer" burial context. Data analyses support the application of biomechanics to osteological analyses in order to assess specialized activity on the skeleton.

Visible and Near-Infrared Spectroscopy Enables Differentiation of Normal and Early Osteoarthritic Human Knee Joint Articular Cartilage

Osteoarthritis degenerates cartilage and impairs joint function. Early intervention opportunities are missed as current diagnostic methods are insensitive to early tissue degeneration. We investigated the capability of visible light-near-infrared spectroscopy (Vis-NIRS) to differentiate normal human cartilage from early osteoarthritic one. Vis-NIRS spectra, biomechanical properties and the state of osteoarthritis (OARSI grade) were quantified from osteochondral samples harvested from different anatomical sites of human cadaver knees. Two support vector machines (SVM) classifiers were developed based on the Vis-NIRS spectra and OARSI scores. The first classifier was designed to distinguish normal (OARSI: 0-1) from general osteoarthritic cartilage (OARSI: 2-5) to check the general suitability of the approach yielding an average accuracy of 75% (AUC = 0.77). Then, the second classifier was designed to distinguish normal from early osteoarthritic cartilage (OARSI: 2-3) yielding an average accuracy of 71% (AUC = 0.73). Important wavelength regions for differentiating normal from early osteoarthritic cartilage were related to collagen organization (wavelength region: 400-600 nm), collagen content (1000-1300 nm) and proteoglycan content (1600-1850 nm). The findings suggest that Vis-NIRS allows objective differentiation of normal and early osteoarthritic tissue, e.g., during arthroscopic repair surgeries.

Enhancement of the therapeutic efficacy of mesenchymal stem cell-derived exosomes in osteoarthritis

Osteoarthritis (OA), a common joint disorder with articular cartilage degradation as the main pathological change, is the major source of pain and disability worldwide. Despite current treatments, the overall treatment outcome is unsatisfactory. Thus, patients with severe OA often require joint replacement surgery. In recent years, mesenchymal stem cells (MSCs) have emerged as a promising therapeutic option for preclinical and clinical palliation of OA. MSC-derived exosomes (MSC-Exos) carrying bioactive molecules of the parental cells, including non-coding RNAs (ncRNAs) and proteins, have demonstrated a significant impact on the modulation of various physiological behaviors of cells in the joint cavity, making them promising candidates for cell-free therapy for OA. This review provides a comprehensive overview of the biosynthesis and composition of MSC-Exos and their mechanisms of action in OA. We also discussed the potential of MSC-Exos as a therapeutic tool for modulating intercellular communication in OA. Additionally, we explored bioengineering approaches to enhance MSC-Exos' therapeutic potential, which may help to overcome challenges and achieve clinically meaningful OA therapies.

Intra-articular delivery of an indoleamine 2,3-dioxygenase galectin-3 fusion protein for osteoarthritis treatment in male Lewis rats

OBJECTIVE

Osteoarthritis (OA) is driven by low-grade inflammation, and controlling local inflammation may offer symptomatic relief. Here, we developed an indoleamine 2,3-dioxygenase and galectin-3 fusion protein (IDO-Gal3), where IDO increases the production of local anti-inflammatory metabolites and Gal3 binds carbohydrates to extend IDO's joint residence time. In this study, we evaluated IDO-Gal3's ability to alter OA-associated inflammation and pain-related behaviors in a rat model of established knee OA.

METHODS

Joint residence was first evaluated with an analog Gal3 fusion protein (NanoLuc™ and Gal3, NL-Gal3) that produces luminescence from furimazine. OA was induced in male Lewis rats via a medial collateral ligament and medial meniscus transection (MCLT + MMT). At 8 weeks, NL or NL-Gal3 were injected intra-articularly (n = 8 per group), and bioluminescence was tracked for 4 weeks. Next, IDO-Gal3s's ability to modulate OA pain and inflammation was assessed. Again, OA was induced via MCLT + MMT in male Lewis rats, with IDO-Gal3 or saline injected into OA-affected knees at 8 weeks post-surgery (n = 7 per group). Gait and tactile sensitivity were then assessed weekly. At 12 weeks, intra-articular levels of IL6, CCL2, and CTXII were assessed.

RESULTS

The Gal3 fusion increased joint residence in OA and contralateral knees (p < 0.0001). In OA-affected animals, both saline and IDO-Gal3 improved tactile sensitivity (p = 0.008), but IDO-Gal3 also increased walking velocities (p ≤ 0.033) and improved vertical ground reaction forces (p ≤ 0.04). Finally, IDO-Gal3 decreased intra-articular IL6 levels within the OA-affected joint (p = 0.0025).

CONCLUSION

Intra-articular IDO-Gal3 delivery provided long-term modulation of joint inflammation and pain-related behaviors in rats with established OA.

Topographical Characterization of the Young, Healthy Human Femoral Medial Condyle

OBJECTIVE

The medial femoral condyle of the knee exhibits some of the highest incidences of chondral degeneration. However, a dearth of healthy human tissues has rendered it difficult to ascertain whether cartilage in this compartment possesses properties that predispose it to injuries. Assessment of young, healthy tissue would be most representative of the tissue's intrinsic properties.

DESIGN

This work examined the topographical differences in tribological, tensile, and compressive properties of young (n = 5, 26.2 ± 5.6 years old), healthy, human medial femoral condyles, obtained from viable allograft specimens. Corresponding to clinical incidences of pathology, it was hypothesized that the lowest mechanical properties would be found in the posterior region of the medial condyle, and that tissue composition would correspond to the established structure-function relationships of cartilage.

RESULTS

Young's modulus, ultimate tensile strength, aggregate modulus, and shear modulus in the posterior region were 1.0-, 2.8-, 1.1-, and 1.0-fold less than the values in the anterior region, respectively. Surprisingly, although glycosaminoglycan content is thought to correlate with compressive properties, in this study, the aggregate and shear moduli correlated more robustly to the amount of pyridinoline crosslinks per collagen. Also, the coefficient of friction was anisotropic and ranged 0.22-0.26 throughout the condyle.

CONCLUSION

This work showed that the posteromedial condyle displays lower tensile and compressive properties, which correlate to collagen crosslinks and may play a role in this region's predisposition to injuries. Furthermore, new structure-function relationships may need to be developed to account for the role of collagen crosslinks in compressive properties.

Evaluation of Cartilage Integrity Following Administration of Oral and Intraarticular Nifedipine in a Murine Model of Osteoarthritis

Osteoarthritis (OA) ranks as the prevailing type of arthritis on a global scale, for which no effective treatments are currently available. Arterial hypertension is a common comorbidity in OA patients, and antihypertensive drugs, such as nifedipine (NIF), may affect the course of OA progression. The aim of this preclinical study was to determine the effect of nifedipine on healthy and OA cartilage, depending on its route of administration. In this study, we used the destabilization of medial meniscus to develop a mouse model of OA. Nifedipine was applied per os or intraarticularly (i.a.) for 8 weeks to both mice with OA and healthy animals. Serum biomarker concentrations were evaluated using the Luminex platform and alterations in the knee cartilage were graded according to OARSI histological scores and investigated immunohistochemically. Nifedipine treatment per os and i.a. exerted protective effects, as assessed by the OARSI histological scores. However, long-term nifedipine i.a. injections induced the deterioration of healthy cartilage. Lubricin, cartilage intermediate layer matrix protein (CILP), collagen type VI (COLVI), CILP, and Ki67 were upregulated by the nifedipine treatment. Serum biomarkers MMP-3, thrombospondin-4, and leptin were upregulated in the healthy groups treated with nifedipine, while only the levels of MMP-3 were significantly higher in the OA group treated with nifedipine per os compared to the untreated group. In conclusion, this study highlights the differential effects of nifedipine on cartilage integrity, depending on the route of administration and cartilage condition.

Notopterol alleviates the progression of osteoarthritis: An in vitro and in vivo study

Osteoarthritis (OA) is a prevalent degenerative joint disorder caused by the progressive destruction of cartilage and inflammation in the articular cavity. Studies have proved that the inhibition of articular cartilage destruction and generation of inflammatory factors can be effective strategies for treating OA. Notopterol (NOT) is a quality control index of Notopterygium incisum Ting ex H. T. Chang (N. incisum) with anti-inflammatory, antioxidant, and analgesic activities. Moreover, NOT has been used for many years to treat joint diseases. A study using human C28/I2 cells suggested that NOT down-regulated the hypersecretion of inflammatory mediators and alleviated the degradation of the extracellular matrix (ECM). In addition, NOT decreased the overproduction of reactive oxygen species (ROS) and chondrocyte apoptosis through the nuclear factor erythroid-2-related factor 2 (Nrf2) signaling pathway. NOT exerted a chondroprotective effect by partly inhibiting the Janus kinase 2/signal transducers and activators of transcription 3 (JAK2/STAT3) and phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) signaling pathways and regulating the nuclear factor Nrf2/heme oxygenase-1(HO-1) signaling pathway. In vivo, NOT improved the destruction of articular cartilage in a rat OA model, which may be related to the inhibition of tumor necrosis factor α (TNF-α), interleukin (IL)-1β, IL-6, and IL-12 expressions in synovial fluid. In summary, these results showed that NOT alleviated the progression of OA and is expected to become a new therapy for treating OA clinically.

Ultrasonographic Evaluation of the Distal Femoral Cartilage Thickness in Parkinson's Patients

OBJECTIVES

Both Parkinson's disease (PD) and osteoarthritis (OA) are characterized by chronic inflammation and tissue degeneration. The aim of this study is to investigate the relationship between PD and distal femoral cartilage thickness (DFCT). Our study is the first in the literature to measure DFCT in PD.

METHODS

68 patients with PD and 30 healthy individuals participated. The patient group was divided into three subgroups, according to the Hoehn Yahr stages (HYS): mild, moderate and severe. Patient subgroups and the control group were compared with each other in terms of neutrophil-lymphocyte ratio (NLR), C-reactive protein (CRP), and DFCT.

RESULTS

The NLR and CRP levels of the PD patients were higher than the values of the healthy people. The DFCT values of the mild PD subgroup were significantly higher than those of the control group, except for one value. The DFCT values of the moderate PD subgroup and the healthy group were similar. The DFCT values of the severe PD subgroup were lower than the values of the healthy group.

CONCLUSIONS

Our study showed the presence of ultrasonographic evidence consistent with early signs of cartilage destruction in early-stage PD disease. As the PD stage progressed, the cartilage thickness decreased accordingly.

Platelet-Derived Exosomes Alleviate Knee Osteoarthritis by Attenuating Cartilage Degeneration and Subchondral Bone Loss

BACKGROUND

Osteoarthritis (OA) is the most prevalent chronic degenerative joint disease among the aged population. However, current treatments for OA are limited to alleviating symptoms, with no therapies that prevent and regenerate cartilage deterioration.

PURPOSE

To assess the effects of platelet-derived exosomes (Plt-exos) on OA and then to explore the potential molecular mechanism.

STUDY DESIGN

Controlled laboratory study.

METHODS

Exosomes derived from human apheresis platelets were isolated and identified. The effects of Plt-exos in protecting chondrocytes under interleukin 1β stimulation were evaluated by analyzing the proliferation and migration in human primary chondrocytes. RNA sequencing was later performed in vitro for primary chondrocytes to reveal the underlying mechanisms of Plt-exo treatment. Anterior cruciate ligament transection was used to construct an OA mice model, and intra-articular injection of Plt-exos was given once a week for 6 weeks. Mice were sacrificed 4 weeks after the last injection. Histologic and immunohistochemistry staining and micro-computed tomography analysis were performed to assess alterations of articular cartilage and subchondral bone.

RESULTS

Plt-exos significantly promoted proliferation and migration of chondrocytes within a dose-dependent manner, as well as dramatically promoted cartilage regeneration and attenuated abnormal tibial subchondral bone remodeling, thus slowing the progression of OA. After being treated with Plt-exos, 1797 genes were differentially expressed in chondrocytes (923 upregulated and 874 downregulated genes). Functional enrichment results and hub genes were mainly involved in anti-inflammatory effects, mediating cell adhesion, stimulating cartilage repair, promoting anabolism, and inhibiting catabolism.

CONCLUSION

Our results demonstrated that Plt-exos promoted chondrocyte proliferation and migration in vitro, as well as attenuated cartilage degeneration, improved the microarchitecture of subchondral bone, and retarded OA progression in vivo.

CLINICAL RELEVANCE

Our study illustrated that the administered Plt-exos could alleviate knee OA by attenuating cartilage degeneration and subchondral bone loss, possibly serving as a novel promising treatment for OA in the future.

Contributions of deep learning to automated numerical modelling of the interaction of electric fields and cartilage tissue based on 3D images

Electric fields find use in tissue engineering but also in sensor applications besides the broad classical application range. Accurate numerical models of electrical stimulation devices can pave the way for effective therapies in cartilage regeneration. To this end, the dielectric properties of the electrically stimulated tissue have to be known. However, knowledge of the dielectric properties is scarce. Electric field-based methods such as impedance spectroscopy enable determining the dielectric properties of tissue samples. To develop a detailed understanding of the interaction of the employed electric fields and the tissue, fine-grained numerical models based on tissue-specific 3D geometries are considered. A crucial ingredient in this approach is the automated generation of numerical models from biomedical images. In this work, we explore classical and artificial intelligence methods for volumetric image segmentation to generate model geometries. We find that deep learning, in particular the StarDist algorithm, permits fast and automatic model geometry and discretisation generation once a sufficient amount of training data is available. Our results suggest that already a small number of 3D images (23 images) is sufficient to achieve 80% accuracy on the test data. The proposed method enables the creation of high-quality meshes without the need for computer-aided design geometry post-processing. Particularly, the computational time for the geometrical model creation was reduced by half. Uncertainty quantification as well as a direct comparison between the deep learning and the classical approach reveal that the numerical results mainly depend on the cell volume. This result motivates further research into impedance sensors for tissue characterisation. The presented approach can significantly improve the accuracy and computational speed of image-based models of electrical stimulation for tissue engineering applications.

Shining Light on Osteoarthritis: Spatially Offset Raman Spectroscopy as a Window into Cartilage Health

Articular cartilage is a complex tissue, and early detection of osteoarthritis (OA) is crucial for effective treatment. However, current imaging modalities lack molecular specificity and primarily detect late-stage changes. In this study, we propose the use of Spatially Offset Raman Spectroscopy (SORS) for non-invasive, depth-dependent, and molecular-specific diagnostics of articular cartilage. We demonstrate the potential of SORS to penetrate deep layers of cartilage, providing a comprehensive understanding of disease progression. Our SORS measurements were characterized and validated through mechanical and histological techniques, revealing strong correlations between spectroscopic measurements and both Young's modulus and depth of cartilage damage. By longitudinally monitoring enzymatically degraded condyles, we further developed a depth-dependent damage-tracking method. Our analysis revealed distinct components related to sample depth and glycosaminoglycan (GAG) changes, offering a comprehensive picture of cartilage health. Collectively, these findings highlight the potential of SORS as a valuable tool for enhancing OA management and improving patient outcomes.

Chelidonine reduces IL-1β-induced inflammation and matrix catabolism in chondrocytes and attenuates cartilage degeneration and synovial inflammation in rats

Chondrocyte inflammation and catabolism are two major features in the progression of osteoarthritis (OA). Chelidonine, a principal alkaloid extracted from Chelidonium majus, is suggested to show anti-inflammation, anti-apoptosis, and anti-oxidation activities in various diseases. However, its potential effects on OA cartilage degeneration remains unclear. To evaluate the effect of chelidonine on OA and its underlying mechanism, we incubated chondrocytes with interleukin (IL)-1β and chelidonine at varying concentrations. Then, we performed the CCK-8 assay, fluorescence immunostaining, reverse transcription PCR, ELISA, and western blotting to evaluate cell viability, catabolic/inflammatory factors, levels of extracellular matrix (ECM)-related proteins, and the involved pathways. H&E and Safranin-O staining and ELISA were performed to measure cartilage degradation and synovial inflammation. Chelidonine suppressed the IL-1β-mediated catabolism and inflammation of chondrocytes. Chelidonine suppressed the NF-κB pathway activation. Similarly, our in vivo experiment showed that chelidonine partially attenuated cartilage degradation while inhibiting synovial inflammation. Chelidonine inhibited inflammation and catabolism through modulation of NF-κB pathways in vitro, thereby avoiding rat cartilage degeneration and synovial inflammation within OA.

Low back pain and osteoarthritis pain: a perspective of estrogen

Low back pain (LBP) is the world's leading cause of disability and is increasing in prevalence more rapidly than any other pain condition. Intervertebral disc (IVD) degeneration and facet joint osteoarthritis (FJOA) are two common causes of LBP, and both occur more frequently in elderly women than in other populations. Moreover, osteoarthritis (OA) and OA pain, regardless of the joint, are experienced by up to twice as many women as men, and this difference is amplified during menopause. Changes in estrogen may be an important contributor to these pain states. Receptors for estrogen have been found within IVD tissue and nearby joints, highlighting the potential roles of estrogen within and surrounding the IVDs and joints. In addition, estrogen supplementation has been shown to be effective at ameliorating IVD degeneration and OA progression, indicating its potential use as a therapeutic agent for people with LBP and OA pain. This review comprehensively examines the relationship between estrogen and these pain conditions by summarizing recent preclinical and clinical findings. The potential molecular mechanisms by which estrogen may relieve LBP associated with IVD degeneration and FJOA and OA pain are discussed.

Development of Therapeutic Agent for Osteoarthritis via Inhibition of KIAA1199 Activity: Effect of Ipriflavone In Vivo

This study aimed to clarify the effects of ipriflavone, which effectively reduces KIAA1199 activity, on osteoarthritis (OA) development and progression in an in vivo OA mouse model. The OA model mice were divided into the ipriflavone (200 mg/kg/day) group and the control group. OA onset and progression were evaluated with the Mankin score, and KIAA1199 expression and hyaluronan (HA) accumulation were analyzed by immunostaining. The molecular weight of HA in the cartilage tissue and serum HA concentration were analyzed by chromatography and competitive HA enzyme-linked immunoassay. The effects of ipriflavone on the bovine cartilage explant culture under the influence of IL-1β were also investigated. In the ipriflavone group, Safranin-O stainability was well-preserved, resulting in significant reduction of the Mankin score (p = 0.027). KIAA1199 staining positivity decreased and HA stainability was preserved in the ipriflavone group. The serum HA concentration decreased, and the molecular weight of HA in the cartilage tissue increased in the ipriflavone group. The results of the cartilage explant culture indicated that ipriflavone could reduce GAG losses and increase the molecular weight of HA. Thus, ipriflavone may have an inhibitory effect on OA development/progression. Ipriflavone could be a therapeutic drug for OA by targeting KIAA1199 activity.

Cross-talk of inflammation and chondrocyte intracellular metabolism in osteoarthritis

Osteoarthritis is a disease that impacts millions around the world, leading to significant financial and medical burden for patients and the healthcare system. However, no effective biomarkers or disease modifying therapeutics exist for the early identification and management of the disease. Inflammation drives chondrocytes to express extracellular matrix (ECM) degrading enzymes and interruption of this pathway is a viable target to prevent degradation of cartilage. It has been demonstrated that inflammation can alter the intracellular metabolism of chondrocytes, a process known as metabolic reprogramming. This metabolic reprogramming is critical for cartilage breakdown by shifting chondrocytes to an ECM-catabolic state and likely as a potential therapeutic target for osteoarthritis. Metabolic modulators hold the potential to reduce chondrocyte inflammatory responses and protect cartilage. In this narrative review, we explore some of the existing examples of interactions between metabolism and inflammatory pathways in chondrocytes. We summarize the impact of inflammatory stimulation on various metabolic pathways and describe several examples by which targeting of metabolism is able to modulate ECM-degrading activity of chondrocytes to protect against cartilage damage.

Ebselen, an Active Seleno-Organic Compound, Alleviates Articular Cartilage Degeneration in a Rat Model of Knee Osteoarthritis

Osteoarthritis (OA) is a prevalent articular disease mainly characterized by extracellular matrix degradation, apoptosis, and inflammation, which lead to cartilage destruction and abnormal bone metabolism. With undesirable side effects, current limited symptomatic treatments are aimed at relieving pain and improving joint mobility in patients with OA. Intra-articular (IA) hyaluronic acid (HA) injection, as a nonsurgical therapy, is commonly used in the clinical management of knee OA, but the efficacy of this therapeutic option remains controversial. Ebselen has tremendous pharmacological importance for some diseases due to its antioxidant, antiapoptotic, and anti-inflammatory features. However, there is no research examining the therapeutic effect of Ebselen in OA using the rat OA model. Therefore, we aimed to investigate the therapeutic effect of Ebselen on cartilage degeneration and its role in bone morphogenetic protein 2 (BMP2) and nuclear factor kappa B (NF-κB) signaling in the molecular pathogenesis of OA. We induced a knee OA model in rats with an IA injection of monosodium-iodoacetate (MIA). After the treatment of Ebselen, we evaluated its chondroprotective effects by morphological, histopathological, and immunohistochemical methods and an enzyme-linked immunosorbent assay. We report for the first time that Ebselen treatment alleviated articular cartilage degeneration in the rat knee OA model and reduced MIA-induced BMP2 and NF-κB expressions. In addition, our results unveiled that Ebselen decreased IL-β and IL-6 levels but did not affect COMP levels in the rat serum. Ebselen could be a promising therapeutic drug for the prevention and treatment of OA by alleviating cartilage degeneration and regulating BMP2 and NF-κB expressions.

Polynucleotides Suppress Inflammation and Stimulate Matrix Synthesis in an In Vitro Cell-Based Osteoarthritis Model

Osteoarthritis (OA) is characterized by degeneration of the joint cartilage, inflammation, and a change in the chondrocyte phenotype. Inflammation also promotes cell hypertrophy in human articular chondrocytes (HC-a) by activating the NF-κB pathway. Chondrocyte hypertrophy and inflammation promote extracellular matrix degradation (ECM). Chondrocytes depend on Smad signaling to control and regulate cell hypertrophy as well as to maintain the ECM. The involvement of these two pathways is crucial for preserving the homeostasis of articular cartilage. In recent years, Polynucleotides Highly Purified Technology (PN-HPT) has emerged as a promising area of research for the treatment of OA. PN-HPT involves the use of polynucleotide-based agents with controlled natural origins and high purification levels. In this study, we focused on evaluating the efficacy of a specific polynucleotide sodium agent, known as CONJURAN, which is derived from fish sperm. Polynucleotides (PN), which are physiologically present in the matrix and function as water-soluble nucleic acids with a gel-like property, have been used to treat patients with OA. However, the specific mechanisms underlying the effect remain unclear. Therefore, we investigated the effect of PN in an OA cell model in which HC-a cells were stimulated with interleukin-1β (IL-1β) with or without PN treatment. The CCK-8 assay was used to assess the cytotoxic effects of PN. Furthermore, the enzyme-linked immunosorbent assay was utilized to detect MMP13 levels, and the nitric oxide assay was utilized to determine the effect of PN on inflammation. The anti-inflammatory effects of PN and related mechanisms were investigated using quantitative PCR, Western blot analysis, and immunofluorescence to examine and analyze relative markers. PN inhibited IL-1β induced destruction of genes and proteins by downregulating the expression of MMP3, MMP13, iNOS, and COX-2 while increasing the expression of aggrecan (ACAN) and collagen II (COL2A1). This study demonstrates, for the first time, that PN exerted anti-inflammatory effects by partially inhibiting the NF-κB pathway and increasing the Smad2/3 pathway. Based on our findings, PN can potentially serve as a treatment for OA.

Small-molecule amines: a big role in the regulation of bone homeostasis

Numerous small-molecule amines (SMAs) play critical roles in maintaining bone homeostasis and promoting bone regeneration regardless of whether they are applied as drugs or biomaterials. On the one hand, SMAs promote bone formation or inhibit bone resorption through the regulation of key molecular signaling pathways in osteoblasts/osteoclasts; on the other hand, owing to their alkaline properties as well as their antioxidant and anti-inflammatory features, most SMAs create a favorable microenvironment for bone homeostasis. However, due to a lack of information on their structure/bioactivity and underlying mechanisms of action, certain SMAs cannot be developed into drugs or biomaterials for bone disease treatment. In this review, we thoroughly summarize the current understanding of SMA effects on bone homeostasis, including descriptions of their classifications, biochemical features, recent research advances in bone biology and related regulatory mechanisms in bone regeneration. In addition, we discuss the challenges and prospects of SMA translational research.