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Tissue engineering strategies show great potential for repairing osteochondral defects in osteoarthritic joints; however, these approaches often rely on passaging cells multiple times to obtain enough cells to produce functional tissue. Unfortunately, monolayer expansion culture causes chondrocyte dedifferentiation, which is accompanied by a phenotypical and morphological shift in chondrocyte properties that leads to a reduction in the quality of de novo cartilage produced. Thus, the objective of this study was to evaluate transcriptional variations during in vitro expansion culture and determine how differences in cell phenotype from monolayer expansion alter development of functional engineered cartilage. We used an unbiased approach to explore genome-wide transcriptional differences in chondrocyte phenotype at passage 1 (P1), P3, and P5, and then seeded cells into hydrogel scaffolds at P3 and P5 to assess cells' abilities to produce cartilaginous extracellular matrix in three dimensional (3D). We identified distinct phenotypic differences, specifically for genes related to extracellular organization and cartilage development. Both P3 and P5 chondrocytes were able to produce chondrogenic tissue in 3D, with P3 cells producing matrix with greater compressive properties and P5 cells secreting matrix with higher glycosaminoglycan/DNA and collagen/DNA ratios. Furthermore, we identified 24 genes that were differentially expressed with passaging and enriched in human osteoarthritis (OA) genome-wide association studies, thereby prioritizing them as functionally relevant targets to improve protocols that recapitulate functional healthy cartilage with cells from adult donors. Specifically, we identified novel genes, such as TMEM190 and RAB11FIP4, which were enriched with human hip OA and may play a role in chondrocyte dedifferentiation. This work lays the foundation for several pathways and genes that could be modulated to enhance the efficacy for chondrocyte culture for tissue regeneration, which could have transformative impacts for cell-based cartilage repair strategies.

Background: Dysregulated circular RNAs (circRNAs) are involved in osteoarthritis (OA) progression. Objective: We aimed to explore the effect of hsa_circ_0044719 (circTRIM25) on the ferroptosis of chondrocytes. Methods: Chondrocytes were treated with interleukin (IL)-1β to generate cell model. Cellular behaviours were measured using cell counting kit-8, enzyme-linked immunosorbent assay, relevant kits, propidium iodide staining, and immunofluorescence assay. Quantitative real-time polymerase chain reaction was performed to examine the expression of circTRIM25, miR-138-5p, and cAMP responsive element binding protein 1 (CREB1), and their interactions were assessed using luciferase reporter analysis and RNA pull-down assay. Results: CircTRIM25 was upregulated in OA tissues and IL-1β-stimulated chondrocytes. Knockdown of circTRIM25 facilitated the viability and suppressed ferroptosis and inflammation of IL-1β-induced cells. CircTRIM25 served as a sponge of miR-138-5p, which directly targets CREB1. Downregulation of miR-138-5p abrogated the effect induced by knockdown of circTRIM25. Furthermore, enforced CREB1 reversed the miR-138-5p induced effect. Moreover, knockdown of circTRIM25 attenuated cartilage injury in vivo. Conclusion: Silencing of circTRIM25 inhibited ferroptosis of chondrocytes via the miR-138-5p/CREB axis and thus attenuated OA progression. [ABSTRACT FROM AUTHOR]

The initial fine-tuning processes are crucial for successful bone regeneration, as they guide skeletal stem cells through progenitor differentiation toward osteo- or chondrogenic fate. While fate determination processes are well-documented, the mechanisms preceding progenitor commitment remain poorly understood. Here, we identified a transcription factor, Zfp260, as pivotal for stem cell maturation into progenitors and directing osteogenic differentiation. Zfp260 is markedly up-regulated as cells transition from stem to progenitor stages; its dysfunction causes lineage arrest at the progenitor stage, impairing bone repair. Zfp260 is required for maintaining chromatin accessibility and regulates Runx2 expression by forming super-enhancer complexes. Furthermore, the PKCα kinase phosphorylates Zfp260 at residues Y173, S182, and S197, which are essential for its functional activity. Mutations at these residues significantly impair its functionality. These findings position Zfp260 as a vital factor bridging stem cell activation with progenitor cell fate determination, unveiling a element fundamental to successful bone regeneration. Yuteng, Wang and colleagues identify the transcription factor Zfp260, which promotes Runx2 expression and is required for differentiation of progenitors from skeletal stem cells and bone repair in mice. [ABSTRACT FROM AUTHOR]

BACKGROUND: For early knee osteoarthritis in which total knee arthroplasty fails to achieve satisfactory results, high tibial osteotomy that has been found to promote regeneration of damaged cartilage and alleviate symptoms in patients is considered a classic knee-preserving procedure. OBJECTIVE: To review and discuss the effectiveness, mechanism, and application prospects of high tibial osteotomy in stimulating cartilage regeneration in knee osteoarthritis and to provide a theoretical basis for the use of high tibial osteotomy in the treatment of knee osteoarthritis. METHODS: A computerized search was conducted in PubMed, Web of Science, CNKI and WanFang databases for relevant literature published from 2013 to 2023. The search terms used were “knee osteoarthritis, high tibial osteotomy, limb alignment, chondrocytes, biomechanics, intra-articular” in both English and Chinese. Finally, 75 articles were included for review. RESULTS AND CONCLUSION: High tibial osteotomy correcting the lower limb alignment has been found to be effective in alleviating symptoms and potentially delaying or preventing the need for total knee arthroplasty. This is an important aspect of orthopedic step-down treatment in knee osteoarthritis. Maintaining a normal mechanical microenvironment is crucial for the proper functioning and maintenance of chondrocyte phenotype. Abnormal mechanical signals can be converted into intracellular chemical signals through mechanosensors like primary cilia, integrins, cytoskeleton and nucleoskeleton, resulting in disruptions to the balance of matrix metabolism and regulation of inflammatory responses. Chondrocytes after abnormal stress action still have the potential to revert to a normal phenotype under appropriate stress; correction of the mechanical microenvironment by high tibial osteotomy leads to spontaneous cartilage repair and remission of synovial inflammation. The combination of high tibial osteotomy and cartilage regeneration strategy holds promising prospects for patients with early knee osteoarthritis who are not candidates for total knee arthroplasty. [ABSTRACT FROM AUTHOR]

The tendon-bone junction (TBJ), a critical transitional zone where tendons and bones connect, is particularly prone to injury due to the forces from muscle contractions and skeletal movements. Once tendon-bone injuries occur, the complex original tissue structure is difficult to restore, increasing the risk of re-tear. In this study, we initially established a rabbit model of tendon-bone injury and treated it using either interference screw or suture anchor. Biomechanical testing demonstrated the maximum tension and strength of TBJ with interference screw fixation were superior. However, histologic and immunohistochemical results showed more tissue regeneration and expression of cartilage markers at the site of injury with suture anchor fixation. Moreover, Gelatin Methacryloyl encapsulated with exosomes from mesenchymal stem cell (GelMA-exosomes) were prepared, showing a consistent and stable exosome release characteristic. The combined application of GelMA-exosomes with either interference screws or suture anchors further enhanced the healing of tendon-bone injuries, which may be achieved by promoting cellular proliferation as well as regulating the decreased expression of local pro-inflammatory factors IL-1β, IL-6 and TNF-α and increased expression of anti-inflammatory factors IL-10 and TGF-β. This provides a viable therapeutic strategy to enhance tendon-bone healing. [ABSTRACT FROM AUTHOR]

Objective: To investigate the impact of different component ratios and mechanical stiffness of the gelatin-sodium alginate composite hydrogel scaffold, fabricated through 3D bioprinting, on the viability and functionality of chondrocytes. Methods: Three different concentrations of hydrogel, designated as low, medium, and high, were prepared. The rheological properties of the hydrogel were characterized to optimize printing parameters. Subsequently, the printability and shape fidelity of the cell-loaded hydrogel scaffolds were statistically evaluated, and the chondrocyte viability was observed. Dynamic mechanical analysis was conducted to measure the modulus, thereby assessing the scaffold's stiffness. Following a 21-day culture period, RT-PCR, histological staining, and immunostaining were employed to assess chondrocyte activity, chondrosphere aggregates formation, and cartilage matrix production. Results: Based on rheological analysis, optimal printing temperatures for each group were determined as 27.8°C, 28.5°C, and 30°C. The optimized printing parameters could ensure the molding effect of the scaffolds on the day of printing, with the actual grid area of the scaffolds was close to the theoretical grid area. And the scaffolds exhibited good cell viability (93.24% ± 0.99%, 92.04% ± 1.49%, and 88.46% ± 1.53%). After 7 days of culture, the medium and high concentration groups showed no significant change in grid area compared to the day of printing (p > 0.05), indicating good morphological fidelity. As the hydrogel's bicomponent ratio increased, both the storage modulus and loss modulus increased, while the loss factor remained relatively constant. The highest number of chondrocytes-formed chondrosphere aggregates in the medium concentration group was observed by light microscopy. RT-PCR results indicated significantly higher expression levels of chondrogenic genes SOX9, Agg, and Col-II in the low and medium concentration groups compared to the high concentration group (p < 0.05). Histological staining results showed that the middle concentration group formed the highest number of typical cartilage lacunae. Conclusion: The aforementioned results indicate that in 3D bioprinted cell-loaded GA-SA composite hydrogel scaffolds, the scaffolds with the composition ratio (10:3) and mechanical stiffness (∼155 kPa) exhibit sustained morphological fidelity, effectively preserve the hyaline phenotype of chondrocytes, and are more conducive to cartilage regeneration. [ABSTRACT FROM AUTHOR]

Bone marrow stem cells (BMSCs)‐engineered cartilage (BEC) shows promise for clinically repairing cartilage defects. However, when implanted in immunocompetent large animals, BEC becomes susceptible to ossification due to inflammatory infiltration. To address this, a nanofilm isolation approach is developed to enhance BEC's chondrogenic stability. Tacrolimus (FK506), known for its immunosuppressive effect, is integrated into adipic dihydrazide (ADH)‐modified hyaluronic acid (HA), creating an acid‐responsive macromolecular prodrug called FK506@HA‐ADH. This prodrug is then blended with poly(lactic‐co‐glycolic acid) (PLGA) to form electrospun FK506@HA/PLGA nanofilm. Goat‐derived BMSCs are induced in vitro to form BEC, which is enclosed within the FK506@HA/PLGA nanofilm and subcutaneously implanted in autologous goats. The nanofilm acted as a physical barrier, preventing immunocyte infiltration. Additionally, in response to the acidic environment triggered by inflammation and the gradual degradation of PLGA, the FK506@HA‐ADH prodrug is cleaved, releasing FK506 as needed. The released FK506 effectively countered inflammatory cytokines and promoted cartilaginous maturity. These combined mechanisms significantly inhibited BEC hypertrophy and improved its chondrogenic stability within an immunocompetent goat model. This nanofilm‐based isolation strategy established an immunosuppressive niche, successfully preventing endochondral ossification and promoting stable cartilage formation in BEC. These advancements are crucial for translating stem cell‐based therapies into clinical use for cartilage repair. [ABSTRACT FROM AUTHOR]

Articular cartilage has limited self-healing ability, resulting in injuries often evolving into osteoarthritis (OA), which poses a significant challenge in the medical field. Although some treatments exist to reduce pain and damage, there is a lack of effective means to promote cartilage regeneration. Reactive Oxygen Species (ROS) have been found to increase significantly in the OA micro-environment. They play a key role in biological systems by participating in cell signaling and maintaining cellular homeostasis. Abnormal ROS expression, caused by internal and external stimuli and tissue damage, leads to elevated levels of oxidative stress, inflammatory responses, cell damage, and impaired tissue repair. To prevent excessive ROS accumulation at injury sites, biological materials can be engineered to respond to the damaged microenvironment, release active components in an orderly manner, regulate ROS levels, reduce oxidative stress, and promote tissue regeneration. Hydrogels have garnered significant attention due to their excellent biocompatibility, tunable physicochemical properties, and drug delivery capabilities. Numerous antioxidant hydrogels have been developed and proven effective in alleviating oxidative stress. This paper discusses a comprehensive treatment strategy that combines antioxidant hydrogels with existing treatments for OA and explores the potential applications of antioxidant hydrogels in cartilage tissue engineering. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA), a common and disabling degenerative joint disease, affects millions of people worldwide and imposes a considerable burden on patients and society due to its high prevalence and economic costs. The pathogenesis of OA is closely related to the progressive degradation of articular cartilage and the accompany inflammation; however, articular cartilage itself cannot heal and modulate the inflammation due to the lack of nerves, blood vessels, and lymph-vessels. Therefore, reliable and effective methods to treat OA remain highly desired. Local administration of drugs or bioactive materials by intra-articular injection of the delivery system represents a promising approach to treat OA, especially considering the prolonged joint retention, cartilage or chondrocytes targeting, and stimuli-responsive release to achieve precision OA therapy. This article summarizes and discusses the advances in the currently used delivery systems (nanoparticle, hydrogel, liposome, and microsphere) and then focuses on their applications in OA treatment from the perspective of endogenous stimulus (redox reactions, pH, enzymes, and temperature) and exogenous stimulus (near-infrared, magnetic, and ultrasound)-responsive release. Finally, the challenges and potential future directions for the development of nano-delivery systems are summarized. [ABSTRACT FROM AUTHOR]

In this study, the optimal engraving parameters were determined through the analysis of scanning electron microscopy (SEM) data, as follows: a laser power density of 5.5 × 105 W/cm2, an irradiation rate of 0.1 mm/s, a well radius of 60 μm, a distance between well centers of 200 μm, and a number of passes for each well of 20. After 1 week of in vitro cultivation, chondrocytes were located on the surface of the scaffolds, in the sockets and lacunae of decellularized cartilage. When implanted into animals, both cellular and acellular scaffolds were able to support cartilage in-growth and complete regeneration of the defect without clear boundaries with normal tissue. Nevertheless, the scaffolds populated with cells exhibited superior biocompatibility and were not subject to rejection, in contrast to cell-free constructs. [ABSTRACT FROM AUTHOR]

In this study, polycaprolactone (PCL) scaffolds have been employed as structural framework scaffolds for patellofemoral cartilage tissue regeneration. The biomechanical and biological properties of different scaffolds were investigated by varying alginate concentrations and the number of scaffold layers. Patellofemoral cartilage defects result in knee pain and reduced mobility, and they are usually treated with conventional methods, often with limited success. Generally, tissue-engineered PCL-alginate scaffolds fabricated by bioprinting technology show promise for enhanced cartilage regeneration due to the biocompatibility and mechanical stability of PCL. In addition, alginate is known for its cell encapsulation capabilities and for promoting cell viability. Biological and morphological assessments, utilizing water contact angle, cell adhesion tests, MTT assays, and scanning electron microscopy (SEM), informed the selection of the optimized scaffold. Comparative analyses between the initial optimal scaffolds with the same chemical composition also included flexural and compression tests and fracture surface observations using SEM. The controlled integration of PCL and alginate offers a hybrid approach, that assembles the mechanical strength of PCL and the bioactive properties of alginate for tissue reconstruction potential. This study aims to identify the most effective scaffold composition for patellofemoral articular cartilage tissue engineering, emphasizing cell viability, structural morphology, and mechanical integrity. The results showed that the optimum biomechanical and biological properties of scaffolds were obtained with a 10% alginate concentration in the monolayer of PCL structure. The findings contribute to regenerative medicine by advancing the understanding of functional tissue constructs, bringing us closer to addressing articular cartilage defects and related clinical challenges. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this consensus was to develop evidence‐ and expert‐based patient‐focused recommendations on the appropriateness of intra‐articular platelet‐rich plasma (PRP) injections in different clinical scenarios of patients with knee osteoarthritis (OA). Methods: The RAND/UCLA Appropriateness Method was used by the European Society of Sports Traumatology, Knee Surgery, and Arthroscopy (ESSKA), as well as the International Cartilage Regeneration and Joint Preservation Society (ICRS) to reach a consensus and produce recommendations for specific patient categories combining best available scientific evidence with the collective judgement of a panel of experts. Results: Scenarios were defined based on first treatment vs first injective treatment vs second injective treatment, age (<50/50–65/66–80/>80), tibiofemoral vs patellofemoral involvement, OA level (Kellgren–Lawrence/KL 0–I/II–III/IV), and joint effusion (dry knee, minor‐mild or major effusion). Out of 216 scenarios, in 84 (38.9%) the indication was considered appropriate, in 9 (4.2%) inappropriate and in 123 (56.9%) uncertain. The parameters associated with the highest consensus were PRP use after failed injective treatments (62.5%), followed by PRP after failed conservative treatments and KL 0–III scenarios (58.3%), while the highest uncertainty was found for PRP use as first treatment and KL IV OA (91.7% and 87.5% of uncertain scenarios, respectively). Conclusion: This ESSKA‐ICRS consensus established recommendations on the appropriateness or inappropriateness of PRP injections for the treatment of knee OA, providing a useful reference for clinical practice. PRP injections are considered appropriate in patients aged ≤80 years with knee KL 0–III OA grade after failed conservative non‐injective or injective treatments, while they are not considered appropriate as first treatment nor in KL IV OA grade. Level of Evidence: Level I. [ABSTRACT FROM AUTHOR]

Objective: To systematically review the clinical efficacy and safety of high tibial osteotomy (HTO) combined with platelet-rich plasma (PRP) for treating knee osteoarthritis (KOA) and to provide evidence of the effectiveness of evidence-based medicine for treating this disease. Methods: Clinical studies on the use of HTO combined with PRP for the treatment of KOA before September 2024 were identified. The literature that met the inclusion criteria was strictly screened out, the literature information was extracted, and the data were input into RevMan5.4 for analysis. Results: Ten studies (12 controls) with 625 patients were included. Overall, the visual analog scale (VAS) score (mean difference (MD) = -0.53, 95% confidence interval (CI) (-0.76, -0.31), P < 0.00001), range of motion (ROM) (MD = 7.24, 95% CI (2.79, 11.69), P = 0.001), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score (MD = -6.91, 95% CI (-9.47, -4.34), P < 0.00001), cartilage recovery (cartilage thickness: MD = 0.43, 95% CI (0.35, 0.51), P < 0.00001; cartilage regeneration: relative risk (RR) = 1.81, 95% CI (1.40, 2.33), P < 0.00001; and the International Cartilage Repair Society (ICRS) grade: RR = 1.96, 95% CI (1.44, 2.66), P < 0.0001), and the Lysholm score (MD = 6.51, 95% CI (4.97, 8.04), P < 0.00001) after HTO-PRP treatment had certain advantages compared to the control group. After treatment, there was no statistically significant difference in the knee joint mechanical axis angle between the HTO-PRP group and the control group (femoral tibial angle (FTA): MD = -0.29, 95% CI (-1.07, 0.49), P = 0.47; medial proximal tibial angle (MPTA): MD = 0.19, 95% CI (-0.49, 0.88), P = 0.58; posterior tibial slope (PTS): MD = -0.12, 95% CI (-0.49, 0.25), P = 0.53; knee varus angle (KVA): MD = -0.30, 95% CI (-1.77, 1.17), P = 0.69; weight-bearing line (WBL): MD = 1.10, 95% CI (-0.89, 3.09), P = 0.28). Conclusion: The results showed that in the treatment of KOA, the HTO-PRP group had better efficacy than the control groups did and had certain safety reliability. [ABSTRACT FROM AUTHOR]

For the non-invasive treatment of rheumatoid arthritis (RA), a chondroitin sulfate C (CSC)-based dissolving microneedles (cMN) was prepared to deliver human adipose stem cell-derived extracellular vesicles (hASC-EV) into inflamed joints. Owing to their anti-inflammatory function, the hASC-EV-bearing cMN (EV@cMN) significantly suppressed activated fibroblast-like synoviocytes (aFLS) and M1 macrophages (M1), which are responsible for the progression of RA. In addition, EV@cMN facilitated the chondrogenic differentiation of bone marrow-derived stem cells. In mice with collagen-induced arthritis, EV@cMN efficiently delivered both hASC-EV and CSC to inflamed joints. Interestingly, pro-inflammatory cytokines in the inflamed joints were remarkably downregulated by the synergistic effect of CSC and hASC-EV. Consequently, as judged from the overall clinical score and joint swelling, EV@cMN showed an outstanding therapeutic effect, even comparable to the wild-type mice, without significant adverse effects. Overall, EV@cMN might have therapeutic potential for RA by efficiently delivering CSC and hASC-EV into the inflamed joints in a non-invasive manner. [Display omitted] • Macrophages and synoviocytes contribute significantly to the progression of rheumatoid arthritis. • Stem cell-derived extracellular vesicle (hASC-EV) inhibits M1 polarization of macrophages. • We discovered that chondroitin sulfate (CSC) reduces the invasiveness of synoviocytes. • Co-delivery of hASC-EV and CSC via microneedle effectively inhibits the progression of RA. [ABSTRACT FROM AUTHOR]

• SERPINA3 was rapidly induced during chondrogenic differentiation from mesenchymal stem cells. • Depletion of SERPINA3 using siRNA led to reduced pellet size and glycosaminoglycan content of cartilage. • RNA sequencing reveals loss of chondrogenic gene expression following SERPINA3 knockdown. • We observed that depletion of this serpin abrogated the induction of the SOX9 protein at early time points. Serine proteinase inhibitors (serpins) are a family of structurally similar proteins which regulate many diverse biological processes from blood coagulation to extracellular matrix (ECM) remodelling. Chondrogenesis involves the condensation and differentiation of mesenchymal stem cells (MSCs) into chondrocytes which occurs during early development. Here, and for the first time, we demonstrate that one serpin, SERPINA3 (gene name SERPINA3, protein also known as alpha-1 antichymotrypsin), plays a critical role in chondrogenic differentiation. We observed that SERPINA3 expression was markedly induced at early time points during in vitro chondrogenesis. We examined the expression of SERPINA3 in human cartilage development, identifying significant enrichment of SERPINA3 in developing cartilage compared to total limb, which correlated with well-described markers of cartilage differentiation. When SERPINA3 was silenced using siRNA, cartilage pellets were smaller and contained lower proteoglycan as determined by dimethyl methylene blue assay (DMMB) and safranin-O staining. Consistent with this, RNA sequencing revealed significant downregulation of genes associated with cartilage ECM formation perturbing chondrogenesis. Conversely, SERPINA3 silencing had a negligible effect on the gene expression profile during osteogenesis suggesting the role of SERPINA3 is specific to chondrocyte differentiation. The global effect on cartilage formation led us to investigate the effect of SERPINA3 silencing on the master transcriptional regulator of chondrogenesis, SOX9. Indeed, we observed that SOX9 protein levels were markedly reduced at early time points suggesting a role for SERPINA3 in regulating SOX9 expression and activity. In summary, our data support a non-redundant role for SERPINA3 in enabling chondrogenesis via regulation of SOX9 levels. [ABSTRACT FROM AUTHOR]

Although autologous chondrocyte transplantation can be effective in articular cartilage repair, negative side effects limit the utility of the treatment, such as long recovery times, poor engraftment or chondrogenic dedifferentiation, and cell leakage. Peptide-based supramolecular polymers have emerged as promising bioactive systems to promote tissue regeneration through cell signaling and dynamic behavior. We report here on the development of a series of glycopeptide amphiphile supramolecular nanofibers with chondrogenic bioactivity. These supramolecular polymers were found to have the ability to boost TGFβ-1 signaling by displaying galactosamine moieties with differing degrees of sulfation on their surfaces. We were also able to encapsulate chondrocytes with these nanostructures as single cells without affecting viability and proliferation. Among the monomers tested, assemblies of trisulfated glycopeptides led to elevated expression of chondrogenic markers relative to those with lower degrees of sulfation that mimic chondroitin sulfate repeating units. We hypothesize the enhanced bioactivity is rooted in specific interactions of the supramolecular assemblies with TGFβ-1 and its consequence on cell signaling, which may involve elevated levels of supramolecular motion as a result of high charge in trisulfated glycopeptide amphiphiles. Our findings suggest that supramolecular polymers formed by the ultra-sulfated glycopeptide amphiphiles could provide better outcomes in chondrocyte transplantation therapies for cartilage regeneration. This study prepares glycopeptide amphiphiles conjugated at their termini with chondroitin sulfate mimetic residues with varying degrees of sulfation that self-assemble into supramolecular nanofibers in aqueous solution. These supramolecular polymers encapsulate chondrocytes as single cells through intimate contact with cell surface structures, forming artificial matrix that can localize the growth factor TGFβ-1 in the intercellular environment. A high degree of sulfation on the glycopeptide amphiphile is found to be critical in elevating chondrogenic cellular responses that supersede the efficacy of natural chondroitin sulfate. This work demonstrates that supramolecular assembly of a unique molecular structure designed to mimic chondroitin sulfate successfully boosts chondrocyte bioactivity by single cell encapsulation, suggesting a new avenue implementing chondrocyte transplantation with supramolecular nanomaterials for cartilage regeneration. [Display omitted] [ABSTRACT FROM AUTHOR]

Understanding matrix molecular activities that regulate the postnatal growth and remodeling of the temporomandibular joint (TMJ) articular disc and condylar cartilage will enable the development of effective regenerative strategies targeting TMJ disorders. This study elucidated the distinct roles of type V collagen (collagen V) in regulating these two units. Studying the TMJ of young adult Col5a1+/− mice, we found that loss of collagen V resulted in substantial changes in the proliferation, clustering and density of progenitors in condylar cartilage, but did not have a major impact on disc cells that are more fibroblast-like. Although loss of collagen V led to thickened collagen fibrils with increased heterogeneity in the disc, there were no significant changes in local micromodulus, except for a reduction at the posterior end of the inferior side. Following the induction of aberrant occlusal loading by the unilateral anterior crossbite (UAC) procedure, both wild-type (WT) and Col5a1+/− condylar cartilage exhibited salient remodeling, and Col5a1+/− condyle developed more pronounced degeneration and tissue hypertrophy at the posterior end than the WT. In contrast, neither UAC nor collagen V deficiency induced marked changes in the morphology or biomechanical properties of the disc. Together, our findings highlight the distinct roles of collagen V in regulating these two units during postnatal growth and remodeling, emphasizing its more crucial role in condylar cartilage due to its impact on the highly mechanosensitive progenitors. These results provide the foundation for using collagen V to improve the regeneration of TMJ and the care of patients with TMJ disorders. Successful regeneration of the temporomandibular joint (TMJ) articular disc and condylar cartilage remains a significant challenge due to the limited understanding of matrix molecular activities that regulate the formation and remodeling of these tissues. This study demonstrates that collagen V plays distinct and critical roles in these processes. In condylar cartilage, collagen V is essential for regulating progenitor cell fate and maintaining matrix integrity. In the disc, collagen V also regulates fibril structure and local micromechanics, but has a limited impact on cell phenotype or its remodeling response. Our findings establish collagen V as a key component in maintaining the integrity of these two units, with a more crucial role in condylar cartilage due to its impact on progenitor cell activities. [Display omitted] [ABSTRACT FROM AUTHOR]

Background/Objectives: Osteoarthritis (OA) is a prevalent and debilitating joint disorder characterized by progressive cartilage degradation and inflammation, for which traditional treatments offer only symptomatic relief without halting disease progression. Exosomes, cell-free vesicles derived from mesenchymal stem cells, have emerged as a promising alternative therapy owing to their regenerative and anti-inflammatory properties. Methods: This review synthesizes findings from recent studies (2017–2023) on the therapeutic potential of exosomes in OA treatment, highlighting their ability to modulate the joint microenvironment, reduce inflammation, and promote cartilage repair by delivering bioactive molecules such as cytokines, growth factors, and regulatory ribonucleic acids. Results: We explore the integration of exosomes with biomaterials, such as hydrogels and scaffolds, to enhance their delivery and therapeutic efficacy, and we address the critical challenges associated with their clinical application, including standardization of isolation and characterization methods, scalability of production, mechanistic understanding, and long-term safety. Despite these challenges, exosome-based therapies offer several advantages over traditional and cell-based treatments, including lower immunogenicity, ease of handling, and targeted delivery of therapeutic agents to damaged tissues. Conclusions: We provide an analytical perspective on the current state of exosome research in OA, emphasizing the need for standardized production methods, deeper mechanistic insights, and rigorous long-term safety assessments. Future directions should focus on optimizing delivery systems, exploring personalized medicine approaches, and conducting comparative effectiveness studies to fully realize the potential of exosome therapies for OA treatment. Addressing these gaps will be crucial for translating exosome therapies from bench to bedside and achieving a transformative impact on OA management. [ABSTRACT FROM AUTHOR]

Hyaluronic acid (HA), an important natural polysaccharide and meanwhile, an essential component of extracellular matrix (ECM), has been widely used in tissue repair and regeneration due to its high biocompatibility, biodegradation, and bioactivity, and the versatile chemical groups for modification. Specially, HA-based dynamic hydrogels, compared with the conventional hydrogels, offer an adaptable network and biomimetic microenvironment to optimize tissue repair and the regeneration process with a striking resemblance to ECM. Herein, this review comprehensively summarizes the recent advances of HA-based dynamic hydrogels and focuses on their applications in articular cartilage repair. First, the fabrication methods and advantages of HA dynamic hydrogels are presented. Then, the applications of HA dynamic hydrogels in cartilage repair are illustrated from the perspective of cell-free and cell-encapsulated and/or bioactive molecules (drugs, factors, and ions). Finally, the current challenges and prospective directions are outlined. [ABSTRACT FROM AUTHOR]

The fibrocartilage stem cells (FCSCs) on the surface of the condyle play an essential role in cartilage homeostasis and regeneration. However, few well-defined stem cell markers have been identified for the analysis of FCSCs' cell fate and regulation mechanism. In this study, we first mapped the transcriptional landscape of the condylar cartilage and identified a Gli1+ subset. Label-retaining cells and our lineage-tracing study showed that Gli1 labeled a group of FCSCs. Conditional knockout β-catenin inhibited Gli1+ cells differentiating into hypertrophic chondrocytes. In discectomy-induced temporomandibular joint osteoarthritis (TMJOA), Gli1+ cells were further activated, and their differentiation into hypertrophic chondrocytes was accelerated, which induced stem cell pool depletion. The deletion of β-catenin in Gli1+ cells preserved the FCSC pool and alleviated TMJOA cartilage degeneration. Collectively, we uncovered that a Gli1+ FCSC subpopulation and Wnt/β-catenin signaling orchestrate the Gli1+ cell fate in condyle postnatal development and TMJOA. [ABSTRACT FROM AUTHOR]

Cartilage damage and degeneration pose significant challenges in orthopedic medicine, innovative approaches for regenerative therapies. The hydrogel is designed to provide a supportive matrix for cell growth and differentiation while delivering therapeutic agents to promote tissue repair. Drug-loaded hydrogels have been extensively studied for cartilage regenerative medicine, offering promising results for tissue engineering and drug delivery applications. These hydrogels, composed of homopolymers and copolymers, can absorb water and create an appropriate microenvironment similar to the extracellular matrix (ECM). Various polymers and crosslinking methods are explored to optimize the hydrogel's mechanical properties, biocompatibility, and drug release kinetics. Additionally, the study investigates the efficacy of different drugs, growth factors, and bioactive molecules for enhancing chondrogenesis and cartilage regeneration within the hydrogel scaffold. The developed drug-loaded hydrogel holds great promise for addressing the unmet clinical need for effective cartilage regenerative therapies, offering potential advancements in orthopedic medicine. [ABSTRACT FROM AUTHOR]

Articular cartilage injuries in the knee can lead to post-traumatic osteoarthritis if untreated, causing debilitating problems later in life. Standard surgical treatments fail to ensure long lasting repair of damaged cartilage, often resulting in fibrotic tissue. While there is a vast amount of research into cartilage regeneration, integrating engineered implants with cartilage remains a challenge. As cartilage is a load bearing tissue, it is imperative to evaluate tissue repair strategies and their ability to integrate under mechanical loading. This work established a dynamically loaded ex vivo model of cartilage repair using human cartilage explants. The model was used to assess the efficacy of a stem cell therapy delivered in a bioadhesive hydrogel comprised of photocrosslinkable gelatin methacryloyl (GelMA) and microbial transglutaminase to repair the model defect. Extensive neocartilage production and integration were observed via histology and immunohistochemistry after 28 days chondrogenic culture. Analysis of culture media allowed monitoring of glycosaminoglycan and type II collagen production over time. A mechanical assessment of integration via a push out test showed a 15-fold increase in push out strength over the culture duration. The model was successful in exhibiting robust chondrogenesis with transglutaminase or without, and under both culture conditions. The work also highlights several limitations of ex vivo models and challenges of working with bioreactors that must be overcome to increase their utility. This ex vivo model has the potential to delay the need for costly pre-clinical studies and provide a more nuanced assessment of cartilage repair strategies than is possible in vivo. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA) is a degenerative disease of the joints, prevalent worldwide. Polydeoxyribonucleotide (PDRN) is used for treating knee OA. However, the role of PDRN in IL-1β-induced inflammatory responses in human bone marrow-derived mesenchymal stem cells (hBMSCs) remains unknown. Here, we investigated the role of PDRN in IL-1β-induced impairment of chondrogenic differentiation in hBMSCs. hBMSCs treated with PDRN showed a large micromass, enhanced safranin O and alcian blue staining intensity, and increased expression of chondrogenic genes in IL-1β-induced inflammatory responses, in addition to regulation of catabolic and anabolic genes. In addition, PDRN treatment suppressed the expression of inflammatory cytokines and mitigated IL-1β-induced apoptosis in hBMSCs. Mechanistically, PDRN treatment increased the formation of cyclic adenosine monophosphate (cAMP) and upregulated the phosphorylation of cAMP-dependent protein kinase A (PKA)/cAMP response element binding protein (CREB) through the adenosine A2A receptor in hBMSCs and thus blocked the nuclear factor kappa-light-chain-enhancer of activated B cell (NF-κB) signaling pathway. Thus, IL-1β-induced expression of inflammatory cytokines in hBMSCs was directly reduced by adenosine A2A receptor activation. Based on our results, we suggest that PDRN may be a promising MSC-based therapeutic agent for OA. [ABSTRACT FROM AUTHOR]

Cartilage defect is one of the common tissue defect clinical diseases and may finally lead to osteoarthritis (OA) which threat patients' physical and psychological health. Polysaccharide is the main component of extracellular matrix (ECM) in cartilage tissue. In the past decades, polysaccharide-based hydrogels have shown great potential for cartilage regeneration considering unique qualities such as biocompatibility, enhanced cell proliferation, drug delivery, low toxicity, and many others. Structures such as chain length and chain branching make polysaccharides have different physical and chemical properties. In this review, cartilage diseases and current treatment options of polysaccharidebased hydrogels for cartilage defection repair were illustrated. We focus on how components and structures of recently developed materials affect the performance. The challenges and perspectives for polysaccharide-based hydrogels in cartilage repair and regeneration were also discussed in depth. [ABSTRACT FROM AUTHOR]

Chondrocytes, the resident cells of articular cartilage, play a vital role in tissue maintenance and regeneration. Recent studies have highlighted chondrocyte senescence as a key contributor to cartilage dysfunction. In this study, we investigated the influence of substrate stiffness on chondrocyte senescence using polydimethylsiloxane (PDMS) substrates with varying stiffness ratios (1:5, 1:20, and 1:60). After culturing chondrocytes on these substrates, we found that softer substrates (1:60) significantly reduced chondrocyte senescence, as evidenced by a decrease in senescence‐associated β‐galactosidase (SA‐β‐gal) activity by 33% compared with stiffer substrates (1:5). Furthermore, quantitative real‐time polymerase chain reaction (PCR) analysis revealed that chondrocytes cultured on softer substrates exhibited lower expression levels of senescence‐related genes (e.g., p16INK4a) and matrix‐degrading enzymes (e.g., MMP13). These findings suggest that substrate stiffness plays a critical role in regulating chondrocyte senescence and could potentially inform the design of scaffolds for cartilage tissue engineering. [ABSTRACT FROM AUTHOR]

Cartilage regeneration relies on adequate and continuous bioenergy supply to facilitate cellular differentiation and extracellular matrix synthesis. Chondrocytes frequently undergo energy stress under pathological conditions, characterized by disrupted cellular metabolism and reduced adenosine triphosphate (ATP) levels. However, there has limited progress in modulating energy metabolism for cartilage regeneration thus far. Here, we developed bioenergetic-active exosomes (Suc-EXO) to promote cartilage regeneration and homeostasis maintenance. Suc-EXO exhibited a 5.42-fold increase in ATP content, enabling the manipulation of cellular energy metabolism by fueling the TCA cycle. With continuous energy supply, Suc-EXO promoted BMSC chondrogenic differentiation via the P2X7-mediated PI3K-AKT pathway. Moreover, Suc-EXO improved chondrocyte anabolism and mitochondrial homeostasis via the P2X7-mediated SIRT3 pathway. In a rabbit cartilage defect model, the Suc-EXO-encapsulated hydrogel notably promoted cartilage regeneration and maintained neocartilage homeostasis, leading to 2.26 and 1.53 times increase in Col2 and ACAN abundance, respectively. These findings make a remarkable breakthrough in modulating energy metabolism for cartilage regeneration, offering immense potential for clinical translation. [ABSTRACT FROM AUTHOR]

Background and objective: The primary cilium is a small protrusion found on most mammalian cells. It acts as a cellular antenna, being involved in various cell signaling pathways. The length of the primary cilium affects its function. To study the impact of physical or chemical stimuli on cilia, their lengths must be determined easily and reproducibly. Methods: We have developed and evaluated an open-source R package called detectCilia to detect and measure primary cilia automatically. As a case study to demonstrate the capability of our tool, we compared the influence of 4 different cell culture media compositions on the lengths of primary cilia in human chondrocytes. These media compositions include (1) insulin-transferrin-selenium (ITS); (2) ITS and dexamethasone (Dexa); (3) ITS, Dexa, insulin-like growth factor 1 (IGF-1), and transforming growth factor beta 1 (TGF-β1); and (4) fetal bovine serum (FBS). Results: The assessment of detectCilia included a comparison with 2 similar tools: ACDC (Automated Cilia Detection in Cells) and CiliaQ. Several differences and advantages of our package make it a valuable addition to these tools. In the case study, we have observed variations in the ciliary lengths associated with using different media compositions. Conclusions: We conclude that detectCilia can automatically and reproducibly detect and measure primary cilia in confocal microscopy images with low false-positive rates without requiring extensive user interaction. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA) is a degenerative joint disease characterized by cartilage degradation and inflammation. This study investigates the therapeutic potential of secretome derived from adipose tissue mesenchymal stem cells (ASCs) in mitigating inflammation and promoting cartilage repair in an in vitro model of OA. Our in vitro model comprised chondrocytes inflamed with TNF. To assess the therapeutic potential of secretome, inflamed chondrocytes were treated with it and concentrations of pro-inflammatory cytokines, metalloproteinases (MMPs) and extracellular matrix markers were measured. In addition, secretome-treated chondrocytes were subject to a microarray analysis to determine which genes were upregulated and which were downregulated. Treating TNF-inflamed chondrocytes with secretome in vitro inhibits the NF-κB pathway, thereby mediating anti-inflammatory and anti-catabolic effects. Additional protective effects of secretome on cartilage are revealed in the inhibition of hypertrophy markers such as RUNX2 and COL10A1, increased production of COL2A1 and ACAN and upregulation of SOX9. These findings suggest that ASC-derived secretome can effectively reduce inflammation, promote cartilage repair, and maintain chondrocyte phenotype. This study highlights the potential of ASC-derived secretome as a novel, non-cell-based therapeutic approach for OA, offering a promising alternative to current treatments by targeting inflammation and cartilage repair mechanisms. [ABSTRACT FROM AUTHOR]

Many tissues have a laminar structure, but there are limited technologies for establishing laminar co-cultures for in vitro testing. Here, we demonstrate that collagen–alginate–fibrin (CAF) hydrogel scaffolds produced using the reactive jet impingement bioprinting technique can produce osteochondral laminar co-cultures with well-defined interfaces between cell types and high cell densities to support cell–cell interaction across the interfaces. The influence of cell density and the presence of the two cell types on the production of extracellular matrix (ECM) and the emergent mechanical properties of gels is investigated using IHC, ELISA, gel mass, and the compression modulus. The results indicate that high-cell-density cultures and co-cultures with these specific cell types produce greater levels of ECM and a more biomimetic in vitro culture than low-cell-density cultures. In laminar scaffolds produced using TC28a2 chondrocytes and SaoS-2 osteoblasts, both cell density and the presence of the two cell types enhance ECM production and the mechanical properties of the cultures, presenting a promising approach for the production of more biomimetic in vitro models. [ABSTRACT FROM AUTHOR]

Osteoarthritis is a common degenerative disease characterized by continuous detachment of lubrication factors from damaged cartilage matrix. This study proposes a paradigm that combines natural polyanionic polysaccharides (hyaluronic acid, HA) with dopamine (DA) to design a synovial lubrication factors‐recruiting biomimetic polyphenolized lubrication system. The biomimetic lubricants can use DA's polarity and hydrophilic groups as specific binding sites of type II collagen's polarity and hydrophilic groups to stably bind cartilage surface, and further utilize molecular specific interaction to recruit detached, joint endogenous or chondrocytes expressed synovial lubrication factors, continuously forming supramolecular lubrication complex onto cartilage matrix to induce joint lubrication. Simultaneously, the biolubricants can also utilize catechol groups to eliminate anionic free radicals and resist reactive oxygen species invasion in the early stages of joint lubrication failure. The prepared biolubricants exhibit low coefficient of friction (µ < 0.08), which is attributed to fluid and hydration lubrication provided by HA and DA side chains through fluid dynamic effect and interfacial hydration adsorption. Cell and animal experiments also demonstrate polyphenolic biolubricants have good biocompatibility and promote cartilage regeneration. Therefore, the developed synovial lubricants‐recruiting biomimetic polyphenolized biolubricants have potential for treating osteoarthritis, and also provide a theoretical basis for other biological tissues with lubrication problems. [ABSTRACT FROM AUTHOR]

Interleukin‐4 (IL‐4)/IL‐4 receptor alpha (IL‐4Rα) signalling pathways play important roles in the complex process of bone formation and bone remodelling. However, whether IL‐4/IL‐4Rα participates in skeletogenesis during embryonic development is not completely understood. We used the anti‐IL‐4Rα monoclonal antibody (anti‐IL‐4Rα mAb) as a powerful investigational tool to evaluate the potential roles of IL‐4/IL‐4Rα in the chondrogenic differentiation of rat bone marrow mesenchymal stem cells (BMSCs) in vitro. Simultaneously, we explored the effect of IL‐4/IL‐4Rα on bone ossification during rat embryo‐fetal development. In this study, we found that, compared to the control group, IL‐4 can significantly promote the chondrogenic differentiation of BMSCs. Furthermore, following exposure to anti‐IL‐4Rα mAb in pregnant rats, unexpected phenomena were observed in fetal bone development, including non‐ossification of the fetal sternum, an incomplete ossification centre in long bones and a reduced number of ossification points in digit (toe) bones. To further investigate the underlying mechanism of the phenotype, we studied the rat sternum as the target organ, starting from different time points of sternum development in the embryonic stage. The results indicated that the retardation mainly occurred in the middle and late stages of embryonic development. This retardation was characterized by the inhibition of the differentiation process of mesenchymal stem cells into chondrocytes, resulting in reduced angiogenesis near the ossification centre, failure of osteoblasts to invade the centre of the cartilage body with the blood vessels and delayed formation of the primary ossification centre (POC). Overall, our study demonstrated the significant function of IL‐4/IL‐4Rα in chondrogenic differentiation of BMSCs and bone ossification during embryo‐fetal development. [ABSTRACT FROM AUTHOR]

Background: The phenomenon of intercellular mitochondrial transfer from mesenchymal stromal cells (MSCs) has shown promise for improving tissue healing after injury and has potential for treating degenerative diseases like osteoarthritis (OA). Recently MSC to chondrocyte mitochondrial transfer has been documented, but the mechanism of transfer is unknown. Full-length connexin 43 (Cx43, encoded by GJA1) and the truncated, internally translated isoform GJA1-20k have been implicated in mitochondrial transfer between highly oxidative cells, but have not been explored in orthopaedic tissues. Here, our goal was to investigate the role of Cx43 in MSC to chondrocyte mitochondrial transfer. In this study, we tested the hypotheses that (a) mitochondrial transfer from MSCs to chondrocytes is increased when chondrocytes are under oxidative stress and (b) MSC Cx43 expression mediates mitochondrial transfer to chondrocytes. Methods: Oxidative stress was induced in immortalized human chondrocytes using tert-Butyl hydroperoxide (t-BHP) and cells were evaluated for mitochondrial membrane depolarization and reactive oxygen species (ROS) production. Human bone-marrow derived MSCs were transduced for mitochondrial fluorescence using lentiviral vectors. MSC Cx43 expression was knocked down using siRNA or overexpressed (GJA1 + and GJA1-20k+) using lentiviral transduction. Chondrocytes and MSCs were co-cultured for 24 h in direct contact or separated using transwells. Mitochondrial transfer was quantified using flow cytometry. Co-cultures were fixed and stained for actin and Cx43 to visualize cell-cell interactions during transfer. Results: Mitochondrial transfer was significantly higher in t-BHP-stressed chondrocytes. Contact co-cultures had significantly higher mitochondrial transfer compared to transwell co-cultures. Confocal images showed direct cell contacts between MSCs and chondrocytes where Cx43 staining was enriched at the terminal ends of actin cellular extensions containing mitochondria in MSCs. MSC Cx43 expression was associated with the magnitude of mitochondrial transfer to chondrocytes; knocking down Cx43 significantly decreased transfer while Cx43 overexpression significantly increased transfer. Interestingly, GJA1-20k expression was highly correlated with incidence of mitochondrial transfer from MSCs to chondrocytes. Conclusions: Overexpression of GJA1-20k in MSCs increases mitochondrial transfer to chondrocytes, highlighting GJA1-20k as a potential target for promoting mitochondrial transfer from MSCs as a regenerative therapy for cartilage tissue repair in OA. [ABSTRACT FROM AUTHOR]

Fibronectin (FN) is an extracellular matrix glycoprotein essential for the development and function of major vertebrate organ systems. Mutations in FN result in an autosomal dominant skeletal dysplasia termed corner fracture-type spondylometaphyseal dysplasia (SMDCF). The precise pathomechanisms through which mutant FN induces impaired skeletal development remain elusive. Here, we have generated patient-derived induced pluripotent stem cells as a cell culture model for SMDCF to investigate the consequences of FN mutations on mesenchymal stem cells (MSCs) and their differentiation into cartilage-producing chondrocytes. In line with our previous data, FN mutations disrupted protein secretion from MSCs, causing a notable increase in intracellular FN and a significant decrease in extracellular FN levels. Analyses of plasma samples from SMDCF patients also showed reduced FN in circulation. FN and endoplasmic reticulum (ER) protein folding chaperones (BIP, HSP47) accumulated in MSCs within ribosome-covered cytosolic vesicles that emerged from the ER. Massive amounts of these vesicles were not cleared from the cytosol, and a smaller subset showed the presence of lysosomal markers. The accumulation of intracellular FN and ER proteins elevated cellular stress markers and altered mitochondrial structure. Bulk RNA sequencing revealed a specific transcriptomic dysregulation of the patient-derived cells relative to controls. Analysis of MSC differentiation into chondrocytes showed impaired mesenchymal condensation, reduced chondrogenic markers, and compromised cell proliferation in mutant cells. Moreover, FN mutant cells exhibited significantly lower transforming growth factor beta-1 (TGFβ1) expression, crucial for mesenchymal condensation. Exogenous FN or TGFβ1 supplementation effectively improved the MSC condensation and promoted chondrogenesis in FN mutant cells. These findings demonstrate the cellular consequences of FN mutations in SMDCF and explain the molecular pathways involved in the associated altered chondrogenesis. Significance/Highlights: • SMDCF-causing mutations in fibronectin impair protein secretion in iPSC-derived mesenchymal stem cells. • Mutant fibronectin and ER protein folding chaperones are directly exported from the rough endoplasmic reticulum into vesicles covered with ribosomes, some of which are positive for lysosomal markers. • The FN mutant cells are characterized by massive accumulation of cytosolic vesicles. • Mutations in fibronectin impair stem cell proliferation, mesenchymal condensation, and the differentiation of MSCs into chondrocytes. • Exogenous addition of purified fibronectin or TGFβ-1 improves mesenchymal condensation and chondrogenesis of the FN mutant stem cells. [ABSTRACT FROM AUTHOR]

OBJECTIVES Tracheal regeneration is challenging owing to its unique anatomy and low blood supply. Most tracheal regeneration applications require scaffolds. Herein, we developed bio-three-dimensional-printed scaffold-free artificial tracheas. METHODS We fabricated bio-three-dimensional-printed artificial tracheas. Their anterior surface comprised hyaline cartilage differentiated from mesenchymal stem cells, and their posterior surface comprised smooth muscle. Human bone marrow-derived mesenchymal stem cells were cultured and differentiated into chondrocytes using fibroblast growth factor-2 and transforming growth factor-beta-3. Initially, horseshoe-shaped spheroids were printed to cover the anterior surface of the artificial trachea, followed by the application of human bronchial smooth muscle cells for the posterior surface. After a 3-week maturing process, the artificial trachea was subjected to histological and immunohistochemical analyses. RESULTS The anterior surface of the artificial trachea comprised well-differentiated hyaline cartilage from human bone marrow-derived mesenchymal stem cells. Immunohistochemistry revealed that the smooth muscle expressed α-smooth muscle actin and smooth muscle myosin heavy chain 11. CONCLUSIONS A bio-three-dimensional-printed scaffold-free artificial trachea comprising different tissues at the front and back was successfully fabricated. [ABSTRACT FROM AUTHOR]

Background: Currently, the use of xenogeneic and allogeneic compounds in the treatment of musculoskeletal diseases is common. Repairing bone and cartilage remains a significant challenge for orthopedic surgeons. One of the principal goals of tissue engineering is the development of appropriate scaffolds that can promote tissue regeneration. Various cells and genes are involved in bone and cartilage regeneration, and new scaffolds can induce these processes during osteoregeneration. Objectives: The aim of this study is to evaluate the effects of umbilical cord blood stem cells (USCs) and platelet-rich fibrin (PRF) using acellular scaffolds in the repair of knee defects in rabbits. Methods: In this study, the femoral patella of 12 male New Zealand rabbits was drilled, and they were divided into four groups: (l) control (rabbits with femoral defects), (2) acellular osteochondral (AO), (3) AO + PRF, and (4) AO + USCs / platelet-rich fibrin. Different scaffolds were implanted into their knees, and after six months, histological evaluations were conducted. To further investigate the effects of scaffolds on bone and cartilage, gene expression levels of Col 1, Col X, Runx2, S0X9, and ALP were measured using real-time PCR. Results: All the implanted materials contributed to knee repair. In terms of statistical analysis, the use of USCs and platelet-rich fibrin with natural scaffolds such as Acellular Osteochondral provided better results for repairing bone and cartilage. The evaluation of specific bone regeneration genes (COLI, RUNX2) and the histological results from the implanted site in experimental osteochondral defects indicated that the most effective knee repair occurred in the group treated with cell-free osteochondral scaffolds, USCs, and platelet-rich fibrin. Conclusions: This study demonstrates that the combination of biomaterials and xenografts can accelerate the regeneration process. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA) is a prominent cause of disability, and has severe social and economic ramifications across the globe. The main driver of OA's pervasiveness is the fact that no current medical interventions exist to reverse or even attenuate the degeneration of cartilage within the articular joint. Crucial for cell-to-cell communication, extracellular vesicles (EVs) contribute to OA progression through the delivery of bioactive molecules in the inflammatory microenvironment. By repurposing this acellular means of signal transmission, therapeutic drugs may be administered to degenerated cartilage tissue in the hopes of encouraging regeneration. Positive outcomes are apparent in in vivo studies on this subject; however, for this therapy to prove itself in the clinical world, efforts towards standardizing the characterization, application, biological contents, and dosage are essential. [ABSTRACT FROM AUTHOR]

Background: Arthritis, a debilitating joint disease, remains a significant global health burden. This study uncovers the therapeutic potential of the medicinal plant Smilax glabra Roxb. (SGR) in attenuating progression of disease by modulating immune responses. Methods: Through computational approaches, key bioactive compounds in SGR were identified by using freely available databases: TCMSP, TCMID, HIT2.0, HERB, and INPUT in order to elucidate their underlying mechanisms of action. Therapeutic targets for the disease have been retrieved by TTD, GeneCard, and OMIM databases. The STRING database was used to analyze the protein–protein interactions (PPI) of intersecting genes. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed to reveal the functional roles of genes. Mcule was used for molecular docking and binding affinity of compounds and targets were evaluated by DeepPurpose model. ALP activity, cell viability assay, TRAP staining were also performed. Results: A total of 14 active SGR compounds with 59 common targets for arthritis have been identified. These targets have a major role in controlling biological processes such as wound healing, oxygen responses, and chemical stimuli. Molecular docking by Mcule platform demonstrated that quercetin and β-sitosterol showed higher binding energy affinities with TNF, TP53, PTGS2, and JUN as compared to other targets. To explore the complex relationship between compounds and targets, pre-trained Davis and KIBA models were used to predict the affinity values of selected compounds. In MC3T3-E1 cells, ALP activity was significantly increased and bone marrow macrophages (BMM) showed a low number of TRAP-positive cells in SGR-treated cells. Conclusions: Our findings demonstrate that SGR effectively inhibits/regulates inflammatory responses, prevents cartilage degradation, promotes bone regeneration, and can be used as a promising candidate for the development of novel arthritis treatment. [ABSTRACT FROM AUTHOR]

In the present work, we introduce a scheme for efficient mechanobiological research on the dedifferentiation of chondrocytes (CHs) using a deep neural network (DNN) model that does not require sacrificing the cells and thus, saving resources. Cells are a part of active biological systems subjected to physical stimuli such as mechanical loading. Such loading affects cellular processes including proliferation, differentiation, and the interplay with the surrounding environment. CHs are mechanosensitive cells that produce and maintain the cartilaginous matrix that allows cartilage to bear and distribute mechanical loads in joints; their role in cartilage regeneration and treatment of osteoarthritis (OA) has been the focus of research projects. Nevertheless, it remains an open challenge to fully understand the effect of mechanical stimuli on CHs. One of the unresolved mechanobiological behaviors of CHs is dedifferentiation. Dedifferentiation of CHs is the phenomenon where isolated CHs alter their phenotype when cultured in a 2D in vitro environment over passages. While intact, cobblestone‐shaped CHs mainly produce collagen II, dedifferentiated CHs with elongated shapes produce fibroblastic collagen I. This limits the scalability of a promising treatment for OA, called 'autologous chondrocyte implantation (ACI)'. To overcome this limit, research is being carried out to understand the dedifferentiation mechanism in detail. This proposed scheme is composed of three parts: (i) the cell‐seeded specimens are loaded in a bioreactor system, (ii) an optical microscope is used to obtain the phase‐contrast images of living cells, and (iii) the images are analyzed using a DNN. This scheme provides an efficient tool to analyze the ratio of intact to dedifferentiated CHs while preserving cells on our way to elucidate the effects of mechanical loading on the dedifferentiation of CHs. [ABSTRACT FROM AUTHOR]

Purpose: Regenerative techniques for articular cartilage lesions demonstrated heterogeneous clinical results. Several factors may influence the outcome, with sex being one of the most debated. This study aimed at quantifying the long‐term influence of sex on the clinical outcome obtained with a regenerative procedure for knee chondral lesions. Methods: Matrix‐assisted autologous chondrocyte transplantation (MACT) was used to treat 235 knees which were prospectively evaluated with the International Knee Documentation Committee (IKDC), EuroQol visual analogue scale, and Tegner scores at 14‐year mean follow‐up. A multilevel analysis was performed with the IKDC subjective scores standardised according to the age/sex category of each patient and/or the selection of a match‐paired subgroup to compare homogeneous men and women patients. Results: At 14 years, men and women showed a failure rate of 10.7% and 28.8%, respectively (p < 0.0005). An overall improvement was observed in both sexes. Women had more patellar lesions and men more condylar lesions (p = 0.001), and the latter also presented a higher preinjury activity level (p < 0.0005). Men had significantly higher IKDC subjective scores at all follow‐ups (at 14 years: 77.2 ± 18.9 vs. 62.8 ± 23.1; p < 0.0005). However, the analysis of homogeneous match‐paired populations of men and women, with standardised IKDC subjective scores, showed no differences between men and women (at 14 years: −1.6 ± 1.7 vs. −1.9 ± 1.6). Conclusion: Men and women treated with MACT for knee chondral lesions presented a significant improvement and stable long‐term results. When both sexes are compared with homogeneous match‐paired groups, they have similar results over time. However, women present more often unfavourable lesion patterns, which proved more challenging in terms of long‐term outcome after MACT. Level of Evidence: Level II. [ABSTRACT FROM AUTHOR]

Background: Cartilage is an avascular and alymphatic tissue that lacks the intrinsic ability to undergo spontaneous repair and regeneration in the event of significant injury. The efficacy of conventional therapies for invasive cartilage injuries is limited, thereby prompting the emergence of cartilage tissue engineering as a possible alternative. In this study, we fabricated three‐dimensional hydrogel films utilizing sodium alginate (SA), gelatin (Gel), and chondroitin sulfate (CS). These films were included with Wharton's jelly mesenchymal stem cells (WJ‐MSCs) and intended for cartilage tissue regeneration. Methods: The hydrogel film that were prepared underwent evaluation using various techniques including scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, assessment of the degree of swelling, degradation analysis, determination of water vapor transmission rate (WVTR), measurement of water contact angle (WCA), evaluation of mechanical strength, and assessment of biocompatibility. The rabbit ear cartilage regeneration by hydrogel films with and without of WJ‐MSCs was studied by histopathological investigations during 15, 30, and 60 days. Results: The hydrogel films containing CS exhibited superior metrics compared to other nanocomposites such as better mechanical strength (12.87 MPa in SA/Gel compared to 15.56 in SA/Gel/CS), stability, hydrophilicity, WVTR (3103.33 g/m2/day in SA/Gel compared to 2646.67 in nanocomposites containing CS), and swelling ratio (6.97 to 12.11% in SA/Gel composite compared to 5.03 to 10.90% in SA/Gel/CS). Histopathological studies showed the presence of chondrocyte cells in the lacunae on the 30th day and the complete restoration of the cartilage tissue on the 60th day following the injury in the group of SA/Gel/CS hydrogel containing WJ‐MSCs. Conclusions: We successfully fabricated a scaffold composed of alginate, gelatin, and chondroitin sulfate. This scaffold was further enhanced by the incorporation of Wharton's jelly mesenchymal stem cells. Our findings demonstrate that this composite scaffold has remarkable biocompatibility and mechanical characteristics. The present study successfully demonstrated the therapeutic potential of the SA‐Gel‐CS hydrogel containing WJ‐MSCs for cartilage regeneration in rabbits. [ABSTRACT FROM AUTHOR]

Simple Summary: Osteoarthritis is a degenerative joint disease. Chronic joint inflammation leads to a loss of joint cartilage. Osteoarthritis is the most common joint disease in dogs and usually develops secondarily as a result of joint incongruence or trauma. Dogs with advanced osteoarthritis often suffer from chronic pain, reduced quality of life and restricted mobility despite pain medication. Conventional treatment options for OA can alleviate the symptoms, but cartilage regeneration is not achieved. Regenerative medicine is increasingly becoming the focus of osteoarthritis research because regenerative cells contribute to tissue healing. The aim of this study was to measure the treatment success of regenerative cell therapy in dogs with chronic osteoarthritis that were no longer responding to pain therapy. The regenerative cells were obtained from the dogs' fatty tissue, processed and applied to the affected joints. Based on the veterinary lameness examination, gait analysis and owner questionnaires, it was assessed whether the regenerative cell therapy led to an improvement in the dogs' lameness and pain. In addition, the animals were X-rayed to measure the progression of osteoarthritis. Some patients showed a therapy-related improvement in lameness and pain. However, the therapy did not have an effect on all patients. This study aimed to assess the efficacy of a single intra-articular injection of autologous stromal vascular fraction (SVF) in dogs with chronic lameness due to advanced elbow osteoarthritis (OA) that were unresponsive to conventional drug therapy. In this clinical, prospective, non-blinded, single-center study, twenty-three dogs received autologous SVF derived from falciform adipose tissue. Primary outcome measures over the six-month study period included clinical-orthopedic and radiographic examinations, objective gait analysis and validated owner questionnaires. In 19 of 23 joints, no progression of OA was visible radiographically. Peak vertical force improved significantly at three months and vertical impulse at six months after the injection compared to baseline. Over 33% of dogs demonstrated treatment-related improvements in lameness based on objective gait analysis. Owner questionnaires indicated significant improvement in clinical signs throughout the study period and 26% of dogs showed treatment-related improvements in pain scores according to the Canine Brief Pain Inventory. No side effects were reported. These findings suggest that autologous regenerative cell therapy may provide a promising treatment option for dogs with advanced OA that do not respond to conventional drug therapy. However, the treatment did not improve the clinical symptoms in all dogs, so it cannot be recommended for all patients. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA) is a chronic, progressive, degenerative joint disease characterized by joint pain, stiffness, and limited movement. It presents significant intra- and inter-individual variability—in particular, between genders. Recent research has increasingly focused on the role of adipokines—especially leptin, adiponectin, and resistin—in the development of OA. Adipokines, peptide hormones primarily secreted by adipose tissue, are involved in crucial physiological processes related to metabolism and immunity. They can also impact bone and cartilage turnover by interacting with joint cells such as osteoblasts, osteoclasts, chondrocytes, and mesenchymal stem cells, thereby linking inflammation with bone cartilage homeostasis. This review aims to elucidate the structure and functions of various adipokines, their serum and synovial levels, and their association with clinical presentation and radiographic progression in OA patients, with a focus on differences between sexes. A narrative literature review was conducted using three databases specifically analyzing sex differences. OA patients generally show elevated serum and synovial levels of leptin, chemerin, and visfatin, as well as high plasma levels of resistin and visfatin. In contrast, synovial levels of adiponectin and omentin are reduced in OA patients compared to healthy individuals, with an inverse relationship to disease severity, suggesting a potential protective role. Resistin and leptin were positively correlated with pain severity and radiographic progression, while adiponectin's role in OA remains controversial. Regarding sex differences, male OA patients exhibited higher serum levels of leptin, chemerin, and omentin compared to healthy controls, with a positive correlation to the BMI and estrogen levels, potentially explaining the sexual dimorphism observed in this condition. Studies on visfatin and lipocalin did not reveal significant differences in synovial or serum levels between the sexes. The role of resistin remains controversial. Adipokines influence the joint microenvironment and contribute to the progression of osteoarthritis (OA). However, the precise biological mechanisms are not yet fully understood due to the complex interactions between the metabolic, mechanical, and immune systems. Further research is needed to clarify their roles in OA and to identify targeted therapies for managing this degenerative disease. [ABSTRACT FROM AUTHOR]

Mesenchymal stromal cells (MSCs) are promising candidates for cartilage repair therapy due to their self-renewal, chondrogenic, and immunomodulatory capacities. It is widely recognized that a shift from fetal bovine serum (FBS)-containing medium toward a fully chemically defined serum-free (SF) medium would be necessary for clinical applications of MSCs to eliminate issues such as xeno-contamination and batch-to-batch variation. However, there is a notable gap in the literature regarding the evaluation of the chondrogenic ability of SF-expanded MSCs (SF-MSCs). In this study, we compared the in vivo regeneration effect of FBS-MSCs and SF-MSCs in a rat osteochondral defect model and found poor cartilage repair outcomes for SF-MSCs. Consequently, a comparative analysis of FBS-MSCs and SF-MSCs expanded using two SF media, MesenCult™-ACF (ACF), and Custom StemPro™ MSC SFM XenoFree (XF) was conducted in vitro. Our results show that SF-expanded MSCs constitute variations in morphology, surface markers, senescence status, differentiation capacity, and senescence/apoptosis status. Highly proliferative MSCs supported by SF medium do not always correlate to their chondrogenic and cartilage repair ability. Prior determination of the SF medium's ability to support the chondrogenic ability of expanded MSCs is therefore crucial when choosing an SF medium to manufacture MSCs for clinical application in cartilage repair. [ABSTRACT FROM AUTHOR]

Treatment of articular cartilage remains a great challenge due to its limited self-repair capability. In tissue engineering, a scaffold with both mechanical strength and regenerative capacity has been highly desired. This study developed a double-network scaffold based on natural biomaterials of silk fibroin (SF) and methacrylated hyaluronic acid (MAHA) using three-dimensional (3D) printing technology. Structural and mechanical characteristics of the scaffold was first investigated. To enhance its ability of recruiting endogenous bone marrow mesenchymal stem cells (BMSCs), the scaffold was conjugated with a proven BMSC-specific-affinity peptide E7, and its biocompatibility and capacity of cell recruitment were assessed in vitro. Animal experiments were conducted to evaluate cartilage regeneration after transplantation of the described scaffolds. The SF/HA scaffolds exhibited a hierarchical macro-microporous structure with ideal mechanical properties, and offered a 3D spatial microenvironment for cell migration and proliferation. In vitro experiments demonstrated excellent biocompatibility of the scaffolds to support BMSCs proliferation, differentiation, and extracellular matrix production. In vivo, superior capacity of cartilage regeneration was displayed by the SF/MAHA + E7 scaffold as compared with microfracture and unconjugated SF/MAHA scaffold based on macroscopic, histologic and imaging evaluation. In conclusion, this structurally and functionally optimized SF/MAHA + E7 scaffold may provide a promising approach to repair articular cartilage lesions in situ. [ABSTRACT FROM AUTHOR]

Articular cartilage degeneration poses a significant public health challenge; techniques such as 3D bioprinting are being explored for its regeneration in vitro. Gelatin-based hydrogels represent one of the most promising biopolymers used in cartilage tissue engineering, especially for its collagen composition and tunable mechanical properties. However, there are no standard protocols that define process parameters such as the crosslinking method to apply. To this aim, a reproducible study was conducted for exploring the influence of different crosslinking methods on 3D bioprinted gelatin structures. This study assessed mechanical properties and cell viability in relation to various crosslinking techniques, revealing promising results particularly for dual (photo + ionic) crosslinking methods, which achieved high cell viability and tunable stiffness. These findings offer new insights into the effects of crosslinking methods on 3D bioprinted gelatin for cartilage applications. For example, ionic and photo-crosslinking methods provide softer materials, with photo-crosslinking supporting cell stretching and diffusion, while ionic crosslinking preserves a spherical stem cell morphology. On the other hand, dual crosslinking provides a stiffer, optimized solution for creating stable cartilage-like constructs. The results of this study offer a new perspective on the standardization of gelatin for cartilage bioprinting, bridging the gap between research and clinical applications. [ABSTRACT FROM AUTHOR]

AbstractDamage to articular cartilage is irreversible and its ability to heal is minimal. The development of articular cartilage in tissue engineering requires suitable biomaterials as scaffolds that provide a 3D natural microenvironment for the development and growth of articular cartilage. This study aims to investigate the applicability of a 3D printed CSH (collagen type II/silk fibroin/hyaluronic acid) scaffold for constructing cartilage tissue engineering. The results showed that the composite scaffold had a three-dimensional porous network structure with uniform pore sizes and good connectivity. The hydrophilicity of the composite scaffold was 1071.7 ± 131.6%, the porosity was 85.12 ± 1.6%, and the compressive elastic modulus was 36.54 ± 2.28 kPa. The creep and stress relaxation constitutive models were also established, which could well describe the visco-elastic mechanical behavior of the scaffold. The biocompatibility experiments showed that the CSH scaffold was very suitable for the adhesion and proliferation of chondrocytes. Under dynamic compressive loading conditions, it was able to promote cell adhesion and proliferation on the scaffold surface. The 3D printed CSH scaffold is expected to be ideal for promoting articular cartilage regeneration. [ABSTRACT FROM AUTHOR]

Superficial cartilage defects represent the most prevalent type of cartilage injury encountered in clinical settings, posing significant treatment challenges. Here, we fabricated a cartilage extracellular matrix mimic hydrogel (GHC, consisting of Gelatin, Hyaluronic acid, and Chondroitin sulfate) to avoid the exacerbation of cartilage deterioration, which is often driven by the accumulation of reactive oxygen species (ROS) and a pro-inflammatory microenvironment. The GHC hydrogel exhibited multifunctional properties, including in situ formation, tissue adhesiveness, anti-ROS capabilities, and the promotion of chondrogenesis. The enhancement of tissue adhesion was achieved by chemically modifying hyaluronic acid and chondroitin sulfate with o-nitrobenzene, enabling a covalent connection to the cartilage surface upon light irradiation. In vitro characterization revealed that GHC hydrogel facilitated chondrocyte adhesion, migration, and differentiation into cartilage. Additionally, GHC hydrogels demonstrated the ability to scavenge ROS in vitro and inhibit the production of inflammatory factors by chondrocytes. In the animal model of superficial cartilage injury, the hydrogel effectively promoted cartilage ECM regeneration and facilitated the interface integration between the host tissue and the material. These findings suggest that the multifunctional GHC hydrogels hold considerable promise as a strategy for cartilage defect repair. Superficial cartilage defects represent the most prevalent type of cartilage injury encountered in the clinic. Previous cartilage tissue engineering materials are only suitable for full-thickness cartilage defects or osteochondral defects. Here, we developed a multifunctional GHC hydrogel composed of gelatin, hyaluronic acid, and chondroitin sulfate, which are natural cartilage extracellular matrix components. The drug-free and cell-free hydrogel not only avoids immune rejection and drug toxicity, but also shows good mechanical properties and biocompatibility. More importantly, the GHC hydrogel could adhere tightly to the superficial cartilage defects and promote cartilage regeneration while protecting against oxidation. This natural ingredients and multifunctional hydrogel is a potential material for repairing superficial cartilage defects. [Display omitted] [ABSTRACT FROM AUTHOR]

Due to the absence of blood vessels and nerves, the regenerative potential of articular cartilage is significantly constrained. This implies that the impact of a ruptured cartilage extends to the entire joint. Osteoarthritis, a health condition, may arise due to injury and the progressive breakdown of joint tissues. The progression of osteoarthritis can be accelerated by the extensive degradation of articular cartilage, which is ranked as the third most prevalent musculoskeletal disorder necessitating rehabilitation, following low back pain and fractures. The existing therapeutic interventions for cartilage repair exhibit limited efficacy and seldom achieve complete restoration of both functional capacity and tissue homeostasis. Emerging technological advancements in the field of tissue engineering hold significant promise for the development of viable substitutes for cartilage tissue, capable of exhibiting functional properties. The overarching strategy involves ensuring that the cell source is enriched with bioactive molecules that facilitate cellular differentiation and/or maturation. This review provides a comprehensive summary of recent advancements in the field of cartilage tissue engineering. Additionally, it offers an overview of recent clinical trials that have been conducted to examine the latest research developments and clinical applications pertaining to weakened articular cartilage and osteoarthritis. [ABSTRACT FROM AUTHOR]

Background: Knee osteoarthritis (OA) significantly affects quality of life and imposes economic burdens due to its prevalence and the disability it causes. The efficacy of current treatments is limited to alleviating the symptoms, and they cannot be used for regenerative purposes. This study aims to evaluate the efficacy and safety of combining hyaluronic acid (HA), human umbilical cord-derived mesenchymal stem cells (hUC-MSCs), and synthetic human growth hormone (somatotropin) in the treatment of knee OA, assessing pain relief, functional improvement, and cartilage regeneration. Methods: A four-arm, double-blind randomized trial was conducted with 51 knees from 28 subjects aged ≥50 with primary knee OA. The treatments involved were HA alone, HA with hUC-MSCs, HA with somatotropin, and a combination of all three. Efficacy was measured through the International Knee Documentation Committee (IKDC) score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and visual analog score (VAS), and MRI T2 mapping of cartilage was conducted on pre-implantation at the 6th and 12th month. Results: All treatment arms showed improvements in the VAS and WOMAC scores over 12 months, suggesting some pain relief and functional improvement. However, MRI T2 mapping showed no significant cartilage regeneration across the groups. Conclusions: While the combined use of HA, hUC-MSCs, and somatotropin improved symptoms of knee OA, it did not enhance cartilage regeneration significantly. This study highlights the potential of these combinations for symptom management but underscores the need for further research to optimize these therapies for regenerative outcomes. [ABSTRACT FROM AUTHOR]

Utilizing transplanted human umbilical cord mesenchymal stem cells (HUMSCs) for cartilage defects yielded advanced tissue regeneration, but the underlying mechanism remain elucidated. Early after HUMSCs delivery to the defects, we observed substantial apoptosis. The released apoptotic vesicles (apoVs) of HUMSCs promoted cartilage regeneration by alleviating the chondro-immune microenvironment. ApoVs triggered M2 polarization in macrophages while simultaneously facilitating the chondrogenic differentiation of endogenous MSCs. Mechanistically, in macrophages, miR-100-5p delivered by apoVs activated the MAPK/ERK signaling pathway to promote M2 polarization. In MSCs, let-7i-5p delivered by apoVs promoted chondrogenic differentiation by targeting the eEF2K/p38 MAPK axis. Consequently, a cell-free cartilage regeneration strategy using apoVs combined with a decellularized cartilage extracellular matrix (DCM) scaffold effectively promoted the regeneration of osteochondral defects. Overall, new mechanisms of cartilage regeneration by transplanted MSCs were unconcealed in this study. Moreover, we provided a novel experimental basis for cell-free tissue engineering-based cartilage regeneration utilizing apoVs.