Enhanced chondrogenic potential in GelMA-based 3D cartilage model via Wnt3a surface immobilization.

Cartilage tissue engineering aims to develop functional substitutes for treating cartilage defects and osteoarthritis. Traditional two-dimensional (2D) cell culture systems lack the complexity of native cartilage, leading to the development of 3D regenerative cartilage models. In this study, we developed a 3D model using Gelatin Methacryloyl (GelMA)-based hydrogels seeded with Y201 cells, a bone marrow mesenchymal stem cell line. The model investigated chondrogenic differentiation potential in response to Wnt3a stimulation within the GelMA scaffold and validated using known chondrogenic agonists. Y201 cells demonstrated suitability for the model, with increased proteoglycan content and upregulated chondrogenic marker expression under chondrogenic conditions. Wnt3a enhanced cell proliferation, indicating activation of the Wnt/ß-catenin pathway, which plays a role in cartilage development. GelMA hydrogels provided an optimal scaffold, supporting cell viability and proliferation. The 3D model exhibited consistent responses to chondrogenic agonists, with TGF-ß3 enhancing cartilage-specific extracellular matrix (ECM) production and chondrogenic differentiation. The combination of Wnt3a and TGF-ß3 showed synergistic effects, promoting chondrogenic differentiation and ECM production. This study presents a 3D regenerative cartilage model with potential for investigating cartilage biology, disease mechanisms, and drug screening. The model provides insights into complex cartilage regeneration mechanisms and offers a platform for developing therapeutic approaches for cartilage repair and osteoarthritis treatment.

Biallelic variants in SLC26A2 cause multiple epiphyseal dysplasia-4 by disturbing chondrocyte homeostasis.

BACKGROUND: Multiple epiphyseal dysplasia-4 (MED-4, MIM 226900) is a rare autosomal recessive disease characterized by disproportionate height and early onset osteoarthritis of the lower limbs. MED-4 is caused by homozygous or compound heterozygous pathogenic variants in the SLC26A2 gene. However, the underlying pathogenic mechanisms in chondrocytes remains unknown. This study aimed to identify the pathogenic variants within a MED-4 family and explore the molecular etiology of this condition in human primary chondrocyte cells. METHODS: Clinical data were recorded and peripheral blood samples were collected for analysis. Whole exome sequencing (WES) and bioinformatic analyses were performed to determine causative variants. Wild-type SLC26A2 and corresponding mutant expression plasmids were constructed and transfected into human primary chondrocytes. The expression and subcellular distribution of SLC26A2 protein in chondrocytes were detected by immunoblotting and immunofluorescence. Effects of these variants on chondrocytes viability and apoptosis were measured by Cell Counting Kit-8 (CCK-8) assay. Expression of genes related to cartilage homeostasis was subsequently analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). RESULTS: We identified two compound heterozygous variants c.1020_1022delTGT(p.Val341del) and c.1262 T > C(p.Ile421Thr) in the SLC26A2 gene in the patients. Mutant SLC26A2Val341del and SLC26A2Ile421Thr proteins were distributed in relatively few cells and were observed only within the nucleus. The viability of chondrocytes with the SLC26A2 variant group was similar to the wild-type (WT) group. However, the protein expressions of SLC26A2Val341del and SLC26A2Ile421Thr were decreased compared with SLC26A2WT. Expression levels of matrix metallopeptidase 13 (MMP13), α-1 chain of type X collagen (COL10A1), and Runt-related transcription factor 2 (RUNX2) were significantly decreased in the variant group. However, aggrecan (ACAN) expression was higher in the variant group than the WT group. CONCLUSIONS: Overall, our data demonstrate that the variants p.Val341del and p.Ile421Thr in SLC26A2 cause MED-4 and that these two variants promote chondrocyte proliferation while inhibiting chondrocyte differentiation.

ER procollagen storage defect without coupled unfolded protein response drives precocious arthritis.

Collagenopathies are a group of clinically diverse disorders caused by defects in collagen folding and secretion. For example, mutations in the gene encoding collagen type-II, the primary collagen in cartilage, can lead to diverse chondrodysplasias. One example is the Gly1170Ser substitution in procollagen-II, which causes precocious osteoarthritis. Here, we biochemically and mechanistically characterize an induced pluripotent stem cell-based cartilage model of this disease, including both hetero- and homozygous genotypes. We show that Gly1170Ser procollagen-II is notably slow to fold and secrete. Instead, procollagen-II accumulates intracellularly, consistent with an endoplasmic reticulum (ER) storage disorder. Likely owing to the unique features of the collagen triple helix, this accumulation is not recognized by the unfolded protein response. Gly1170Ser procollagen-II interacts to a greater extent than wild-type with specific ER proteostasis network components, consistent with its slow folding. These findings provide mechanistic elucidation into the etiology of this disease. Moreover, the easily expandable cartilage model will enable rapid testing of therapeutic strategies to restore proteostasis in the collagenopathies.

[Analysis of genetic variants and molecular pathogenesis in a Chinese pedigree affected with Multiple epiphyseal dysplasia].

OBJECTIVE: To analyze the genetic variant and molecular pathogenesis in a Chinese pedigree affected with Multiple epiphyseal dysplasia (MED). METHODS: A MED pedigree which had presented at the Beijing Jishuitan Hospital Affiliated to Capital Medical University on September 13, 2020 was selected as the study subject. Clinical data of the pedigree were collected. Peripheral blood samples were drawn from pedigree members for the extraction of genomic DNA. Whole exome sequencing (WES) was carried out for the pedigree. Candidate variant was verified by Sanger sequencing. Wild type and mutant SLC26A2 expression plasmids were constructed and transfected into human primary chondrocytes. The effect of the variants on the protein localization and cell proliferation was determined by immunofluorescence and CCK8 assays. RESULTS: WES and Sanger sequencing revealed that the proband has harbored compound heterozygous variants of the SLC26A2 gene, including a paternally derived c.484G>T (p.Val162Leu) missense variant and a maternally derived c.485_486delTG (p.Val162Glyfs*12) frameshifting variant. The SLC26A2WT and its mutant SLC26A2Val162Leu and SLC26A2Val162Glyfs*12 expression plasmids were distributed in the nuclei and cytoplasm of human primary chondrocytes. Compared with SLC26A2WT, the expressions of SLC26A2Val162Leu and SLC26A2Val162Glyfs*12 were decreased, along with reduced proliferation of human primary chondrocytes. CONCLUSION: The c.484G>T and c.485_486delTG compound heterozygous variants of the SLC26A2 gene may affect the proliferation of human primary chondrocytes and underlay the pathogenesis of MED in this pedigree.

Osteocyte-derived exosomes regulate the DLX2/wnt pathway to alleviate osteoarthritis by mediating cartilage repair.

BACKGROUND: Chondrocyte viability, apoptosis, and migration are closely related to cartilage injury in osteoarthritis (OA) joints. Exosomes are identified as potential therapeutic agents for OA. OBJECTIVE: This study aimed to investigate the role of exosomes derived from osteocytes in OA, particularly focusing on their effects on cartilage repair and molecular mechanisms. METHODS: An injury cell model was established by treating chondrocytes with IL-1ß. Cartilage repair was evaluated using cell counting kit-8, flow cytometry, scratch test, and Western Blot. Molecular mechanisms were analyzed using quantitative real-time PCR, bioinformatic analysis, and Western Blot. An OA mouse model was established to explore the role of exosomal DLX2 in vivo. RESULTS: Osteocyte-released exosomes promoted cell viability and migration, and inhibited apoptosis and extracellular matrix (ECM) deposition. Moreover, exosomes upregulated DLX2 expression, and knockdown of DLX2 activated the Wnt pathway. Additionally, exosomes attenuated OA in mice by transmitting DLX2. CONCLUSION: Osteocyte-derived exosomal DLX2 alleviated IL-1ß-induced cartilage repair and inactivated the Wnt pathway, thereby alleviating OA progression. The findings suggested that osteocyte-derived exosomes may hold promise as a treatment for OA.

Synergistic Effects of Icariin and Extracellular Vesicles Derived from Rabbit Synovial Membrane-Derived Mesenchymal Stem Cells on Osteochondral Repair via the Wnt/ß-Catenin Pathway.

Objectives: Osteochondral defects (OCDs) are localized areas of damaged cartilage and underlying subchondral bone that can produce pain and seriously impair joint function. Literature reports indicated that icariin (ICA) has the effect of promoting cartilage repair. However, its mechanism remains unclear. Here, we explored the effects of icariin and extracellular vesicles (EVs) from rabbit synovial-derived mesenchymal stem cells (rSMSCs) on repairing of OCDs. Materials and Methods: Rabbit primary genicular chondrocytes (rPGCs), knee skeletal muscle cells (rSMCKs), and rSMSCs, and extracellular vesicles derived from the latter two cells (rSMCK-EVs and rSMSC-EVs) were isolated and identified. The rPGCs were stimulated with ICA, rSMSC-EVs either separately or in combination. The rSMCK-EVs were used as a control. After stimulation, chondrogenic-related markers were analyzed by quantitative RT-PCR and western blotting. Cell proliferation was determined by the CCK-8 assay. The preventative effects of ICA and SMSC-EVs in vivo were determined by H&E and toluidine blue staining. Immunohistochemical analyses were performed to evaluate the levels of COL2A1 and ß-catenin in vivo. Results. In vitro, the proliferation of rPGCs was markedly increased by ICA treatment in a dose-dependent manner. When compared with ICA or rSMSC-EVs treatment alone, combined treatment with ICA and SMSC-EVs produced stronger stimulative effects on cell proliferation. Moreover, combined treatment with ICA and rSMSC-EVs promoted the expression of chondrogenic-related gene, including COL2A1, SOX-9, and RUNX2, which may be via the activation of the Wnt/ß-catenin pathway. In vivo, combined treatment with rSMSC-EVs and ICA promoted cartilage repair in joint bone defects. Results also showed that ICA or rSMSC-EVs both promoted the COL2A1 and ß-catenin protein accumulation in articular cartilage, and that was further enhanced by combined treatment with rSMSC-EVs and ICA. Conclusion: Our findings highlight the promising potential of using combined treatment with ICA and rSMSC-EVs for promoting osteochondral repair.

The chondrocyte "mechanome": Activation of the mechanosensitive ion channels TRPV4 and PIEZO1 drives unique transcriptional signatures.

The mechanosensitive ion channels Transient Receptor Potential Vanilloid 4 (TRPV4) and PIEZO1 transduce physiologic and supraphysiologic magnitudes of mechanical signals in the chondrocyte, respectively. TRPV4 activation promotes chondrogenesis, while PIEZO1 activation by supraphysiologic deformations drives cell death. The mechanisms by which activation of these channels discretely drives changes in gene expression to alter cell behavior remain to be determined. To date, no studies have contrasted the transcriptomic response to activation of these channels nor has any published data attempted to correlate these transcriptomes to alterations in cellular function. This study used RNA sequencing to comprehensively investigate the transcriptomes associated with activation of TRPV4 or PIEZO1, revealing that TRPV4 and PIEZO drive distinct transcriptomes and also exhibit unique co-regulated clusters of genes. Notably, activation of PIEZO1 through supraphysiologic deformation induced a transient inflammatory profile that overlapped with the interleukin (IL)-1-responsive transcriptome and contained genes associated with cartilage degradation and osteoarthritis progression. However, both TRPV4 and PIEZO1 were also shown to elicit anabolic effects. PIEZO1 expression promoted a pro-chondrogenic transcriptome under unloaded conditions, and daily treatment with PIEZO1 agonist Yoda1 significantly increased sulfated glycosaminoglycan deposition in vitro. These findings emphasize the presence of a broad "mechanome" with distinct effects of TRPV4 and PIEZO1 activation in chondrocytes, suggesting complex roles for PIEZO1 in both the physiologic and pathologic responses of chondrocytes. The identification of transcriptomic profiles unique to or shared by PIEZO1 and TRPV4 (distinct from IL-1-induced inflammation) could inform future therapeutic designs targeting these channels for the management and treatment of osteoarthritis.

Novel Treatment Options for Knee Cartilage Defects in 2023.

Articular cartilage lesions are a common injury that have become increasingly treatable with joint preservation procedures. Well-documented allograft and cellular treatments for these lesions are detailed elsewhere in this volume. This article discusses three new unique options for addressing these defects taking three different paths to address these complex injuries. Agili-C is an existing FDA- and EMEA-approved option using an acellular aragonite-based scaffold to treat both chondral and osteochondral lesions, with or without concurrent arthritis. Cartistem is a stem-cell-based product composed of culture-expanded allogeneic human umbilical cord blood-derived mesenchymal stem cells and hyaluronic acid hydrogel, which is in its final clinical trial stages in the United States, but already has regulatory approval in Korea. IMPACT and RECLAIM studies have shown the safety and efficacy of a new one-stage procedure utilizing autologous chondrons combined with allogeneic mesenchymal stem cells (MSCs) that can provide another effective single-stage treatment option.

Treatment of Shoulder Cartilage Defects in Athletes.

Articular cartilage defects in the glenohumeral joint may be found in laborers, the elderly, and young athletes, among others. Various factors can contribute to cartilage damage, including prior surgery, trauma, avascular necrosis, inflammatory arthritis, joint instability, and osteoarthritis. There is a wide variety of treatment options, from conservative treatment, injections, and surgical options, including arthroscopic debridement, microfracture, osteochondral autograft transfer, osteochondral graft transplantation, autologous chondrocyte implantation, and the newly emerging techniques such as biologic augmentation. There is a challenge to determine the optimal treatment options, especially for young athletes, due to limited outcomes in the literature. However, there are many options which are viable to address osteochondral defects of the glenohumeral joint.

Silencing of CircTRIM25/miR-138-5p/CREB1 axis promotes chondrogenesis in osteoarthritis.

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)-1ß 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-1ß-stimulated chondrocytes. Knockdown of circTRIM25 facilitated the viability and suppressed ferroptosis and inflammation of IL-1ß-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.

Cinnamaldehyde-Treated Bone Marrow Mesenchymal-Stem-Cell-Derived Exosomes via Aqueous Two-Phase System Attenuate IL-1ß-Induced Inflammation and Catabolism via Modulation of Proinflammatory Signaling Pathways.

Osteoarthritis (OA) is a degenerative joint disorder that is distinguished by inflammation and chronic cartilage damage. Interleukin-1ß (IL-1ß) is a proinflammatory cytokine that plays an important role in the catabolic processes that underlie the pathogenesis of OA. In this study, we investigate the therapeutic efficacy of exosomes derived from untreated bone-marrow-derived mesenchymal stem cells (BMMSC-Exo) and those treated with cinnamaldehyde (BMMSC-CA-Exo) for preventing the in vitro catabolic effects of IL-1ß on chondrocytes. We stimulated chondrocytes with IL-1ß to mimic the inflammatory microenvironment of OA. We then treated these chondrocytes with BMMSC-Exo and BMMSC-CA-Exo isolated via an aqueous two-phase system and evaluated their effects on the key cellular processes using molecular techniques. Our findings revealed that treatment with BMMSC-Exo reduces the catabolic effects of IL-1ß on chondrocytes and alleviates inflammation. However, further studies directly comparing treatments with BMMSC-Exo and BMMSC-CA-Exo are needed to determine if CA preconditioning can provide additional anti-inflammatory benefits to the exosomes beyond those of CA preconditioning or treatment with regular BMMSC-Exo. Through a comprehensive molecular analysis, we elucidated the regulatory mechanisms underlying this protective effect. We found a significant downregulation of proinflammatory signaling pathways in exosome-infected chondrocytes, suggesting the potential modulation of the NF-κB and MAPK signaling cascades. Furthermore, our study identified the molecular cargo of BMMSC-Exo and BMMSC-CA-Exo, determining the key molecules, such as anti-inflammatory cytokines and cartilage-associated factors, that may contribute to their acquisition of chondroprotective properties. In summary, BMMSC-Exo and BMMSC-CA-Exo exhibit the potential as therapeutic agents for OA by antagonizing the in vitro catabolic effects of IL-1ß on chondrocytes. The regulation of the proinflammatory signaling pathways and bioactive molecules delivered by the exosomes suggests a multifaceted mechanism of action. These findings highlight the need for further investigation into exosome-based therapies for OA and joint-related diseases.

Quercetin Modulates Ferroptosis via the SIRT1/Nrf-2/HO-1 Pathway and Attenuates Cartilage Destruction in an Osteoarthritis Rat Model.

Osteoarthritis (OA) is the most common joint disease, causing symptoms such as joint pain, swelling, and deformity, which severely affect patients' quality of life. Despite advances in medical treatment, OA management remains challenging, necessitating the development of safe and effective drugs. Quercetin (QUE), a natural flavonoid widely found in fruits and vegetables, shows promise due to its broad range of pharmacological effects, particularly in various degenerative diseases. However, its role in preventing OA progression and its underlying mechanisms remain unclear. In this study, we demonstrated that QUE has a protective effect against OA development both in vivo and in vitro, and we elucidated the underlying molecular mechanisms. In vitro, QUE inhibited the expression of IL-1ß-induced chondrocyte matrix metalloproteinases (MMP3 and MMP13) and inflammatory mediators such as INOS and COX-2. It also promoted the expression of collagen II, thereby preventing the extracellular matrix (ECM). Mechanistically, QUE exerts its protective effect on chondrocytes by activating the SIRT1/Nrf-2/HO-1 and inhibiting chondrocyte ferroptosis. Similarly, in an OA rat model induced by anterior cruciate ligament transection (ACLT), QUE treatment improved articular cartilage damage, reduced joint pain, and normalized abnormal subchondral bone remodeling. QUE also reduced serum IL-1ß, TNF-α, MMP3, CTX-II, and COMP, thereby slowing the progression of OA. QUE exerts chondroprotective effects by inhibiting chondrocyte oxidative damage and ferroptosis through the SIRT1/Nrf-2/HO-1 pathway, effectively alleviating OA progression in rats.

Protective effect of clusterin against interleukin-1ß-induced apoptosis and inflammation in human knee osteoarthritis chondrocytes.

Chondrocyte apoptosis is recognized as one of the pathological features involved in cartilage degeneration driving the onset and progression of knee osteoarthritis (OA). This study aimed to determine the molecular mechanism underlying the effect of clusterin (CLU), anti-apoptotic molecule, in human knee OA chondrocytes. Primary knee OA chondrocytes were isolated from the cartilage of knee OA patients and divided into five groups: (1) the cells treated with interleukin (IL)-1ß, (2) CLU alone, (3) a combination of IL-1ß and CLU, (4) LY294002 (PI3K inhibitor) along with IL-1ß and CLU, and (5) the untreated cells. Production of apoptotic, inflammatory, anabolic, and catabolic mediators in knee OA chondrocytes was determined after treatment for 24 h. Our in vitro study uncovered that CLU significantly suppressed the production of inflammatory mediators [nitric oxide (NO), IL6, and tumor necrosis factor (TNF)-α] and apoptotic molecule (caspase-3, CASP3). CLU significantly upregulated messenger ribonucleic acid (mRNA) expressions of anabolic factors [SRY-box transcription factor-9 (SOX9) and aggrecan (ACAN)], but significantly downregulated mRNA expressions of IL6, nuclear factor kappa-B (NF-κB), CASP3, and matrix metalloproteinase-13 (MMP13). Anti-apoptotic and anti-inflammatory effects of CLU were mediated through activating PI3K/Akt signaling pathway. The findings suggest that CLU might have beneficial effects on knee OA chondrocytes by exerting anti-apoptotic and anti-inflammatory functions via PI3K/Akt pathway, making CLU a promising target for potential therapeutic interventions in knee OA.

[Advances in clinical repair techniques for localized knee cartilage lesions].

Objective: To summarize the classic and latest treatment techniques for localized knee cartilage lesions in clinical practice and create a new comprehensive clinical decision-making process. Methods: The advantages and limitations of various treatment methods for localized knee cartilage lesions were summarized by extensive review of relevant literature at home and abroad in recent years. Results: Currently, there are various surgical methods for treating localized knee cartilage injuries in clinical practice, each with its own pros and cons. For patients with cartilage injuries less than 2 cm 2 and 2-4 cm 2 with bone loss are recommended to undergo osteochondral autograft (OAT) and osteochondral allograft (OCA) surgeries. For patients with cartilage injuries less than 2 cm 2 and 2-4 cm 2 without bone loss had treatment options including bone marrow-based techniques (micro-fracture and ogous matrix induced chondrogenesis), autologous chondrocyte implantation (ACI)/matrix-induced ACI, particulated juvenile allograft cartilage (PJAC), OAT, and OCA. For patients with cartilage injuries larger than 4 cm 2 with bone loss were recommended to undergo OCA. For patients with cartilage injuries larger than 4 cm 2 without bone loss, treatment options included ACI/matrix-induced ACI, OAT, and PJAC. Conclusion: There are many treatment techniques available for localized knee cartilage lesions. Treatment strategy selection should be based on the size and location of the lesion, the extent of involvement of the subchondral bone, and the level of evidence supporting each technique in the literature.

Circadian rhythm disruption upregulating Per1 in mandibular condylar chondrocytes mediating temporomandibular joint osteoarthritis via GSK3ß/ß-CATENIN pathway.

BACKGROUND: Temporomandibular joint osteoarthritis (TMJOA) has a high incidence rate, but its pathogenesis remains unclear. Circadian rhythm is an important oscillation in the human body and influences various biological activities. However, it is still unclear whether circadian rhythm affects the onset and development of TMJOA. METHODS: We disrupted the normal rhythm of rats and examined the expression of core clock genes in the mandibular condylar cartilage of the jaw and histological changes in condyles. After isolating rat mandibular condylar chondrocytes, we upregulated or downregulated the clock gene Per1, examined the expression of cartilage matrix-degrading enzymes, tested the activation of the GSK3ß/ß-CATENIN pathway and verified it using agonists and inhibitors. Finally, after downregulating the expression of Per1 in the mandibular condylar cartilage of rats with jet lag, we examined the expression of cartilage matrix-degrading enzymes and histological changes in condyles. RESULTS: Jet lag led to TMJOA-like lesions in the rat mandibular condyles, and the expression of the clock gene Per1 and cartilage matrix-degrading enzymes increased in the condylar cartilage of rats. When Per1 was downregulated or upregulated in mandibular condylar chondrocytes, the GSK3ß/ß-CATENIN pathway was inhibited or activated, and the expression of cartilage matrix-degrading enzymes decreased or increased, which can be rescued by activator and inhibitor of the GSK3ß/ß-CATENIN pathway. Moreover, after down-regulation of Per1 in mandibular condylar cartilage in vivo, significant alleviation of cartilage degradation, cartilage loss, subchondral bone loss induced by jet lag, and inhibition of the GSK3ß/ß-CATENIN signaling pathway were observed. Circadian rhythm disruption can lead to TMJOA. The clock gene Per1 can promote the occurrence of TMJOA by activating the GSK3ß/ß-CATENIN pathway and promoting the expression of cartilage matrix-degrading enzymes. The clock gene Per1 is a target for the prevention and treatment of TMJOA.

Auricular Chondrocytes as a Cell Source for Scaffold-Free Elastic Cartilage Tissue Engineering.

Current tissue engineering (TE) methods utilize chondrocytes primarily from costal or articular sources. Despite the robust mechanical properties of neocartilages sourced from these cells, the lack of elasticity and invasiveness of cell collection from these sources negatively impact clinical translation. These limitations invited the exploration of naturally elastic auricular cartilage as an alternative cell source. This study aimed to determine if auricular chondrocytes (AuCs) can be used for TE scaffold-free neocartilage constructs and assess their biomechanical properties. Neocartilages were successfully generated from a small quantity of primary neonatal AuCs of three minipig donors (n = 3). Neocartilage constructs had instantaneous moduli of 200.5 kPa ± 43.34 and 471.9 ± 92.8 kPa at 10% and 20% strain, respectively. TE constructs' relaxation moduli (Er) were 36.99 ± 6.47 kPa Er and 110.3 ± 16.99 kPa at 10% and 20% strain, respectively. The Young's modulus was 2.0 MPa ± 0.63, and the ultimate tensile strength was 0.619 ± 0.177 MPa. AuC-derived neocartilages contained 0.144 ± 0.011 µg collagen, 0.185 µg ± 0.002 glycosaminoglycans per µg dry weight, and 1.7e-3 µg elastin per µg dry weight. In conclusion, this study shows that AuCs can be used as a reliable and easily accessible cell source for TE of biomimetic and mechanically robust elastic neocartilage implants.

A quality by design approach to optimise disulfide-linked hyaluronic acid hydrogels.

In this study, the disulfide-linked hyaluronic acid (HA) hydrogels were optimised for potential application as a scaffold in tissue engineering through the Quality by Design (QbD) approach. For this purpose, HA was first modified by incorporating the cysteine moiety into the HA backbone, which promoted the formation of disulfide cross-linked HA hydrogel at physiological pH. Utilising a Design of Experiments (DoE) methodology, the critical factors to achieve stable biomaterials, i.e. the degree of HA substitution, HA molecular weight, and coupling agent ratio, were explored. To establish a design space, the DoE was performed with 65 kDa, 138 kDa and 200 kDa HA and variable concentrations of coupling agent to optimise conditions to obtain HA hydrogel with improved rheological properties. Thus, HA hydrogel with a 12 % degree of modification, storage modulus of ≈2321 Pa and loss modulus of ≈15 Pa, was achieved with the optimum ratio of coupling agent. Furthermore, biocompatibility assessments in C28/I2 chondrocyte cells demonstrated the non-toxic nature of the hydrogel, underscoring its potential for tissue regeneration. Our findings highlight the efficacy of the QbD approach in designing HA hydrogels with tailored properties for biomedical applications.

The Nrf2/HO-1 pathway participates in the antiapoptotic and anti-inflammatory effects of platelet-rich plasma in the treatment of osteoarthritis.

INTRODUCTION: We aimed to explore the molecular mechanisms through which platelet-rich plasma (PRP) attenuates osteoarthritis (OA)-induced pain, apoptosis, and inflammation. METHODS: An in vivo model of OA was established by injuring rats using the anterior cruciate ligament transection method, whereas an in vitro model was generated by exposing chondrocytes to interleukin (IL)-1ß. Both models were then treated with PRP. RESULTS: In both the in vivo and in vitro models, OA led to the suppression of the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway, whereas treatment with PRP reactivated this molecular axis. Inhibition of the Nrf2/HO-1 pathway using the Nrf2 inhibitor brusatol or through Nrf2 gene silencing counteracted the effects of PRP in reducing the tenderness and thermal pain thresholds of OA rats. Additionally, PRP reduced the mRNA expression of IL-1ß, IL-6, tumor necrosis factor-alpha (TNF-α), and matrix metallopeptidase 13 (MMP-13) and the protein expression of B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X-protein (Bax), and caspase-3. Furthermore, inflammation and apoptosis were induced by brusatol treatment or Nrf2 silencing. Additionally, in the in vitro model, PRP treatment increased the proliferation of chondrocytes and attenuated their inflammatory response and apoptosis, effects that were abrogated by Nrf2 depletion. CONCLUSIONS: The Nrf2/HO-1 pathway participates in the PRP-mediated attenuation of OA development by suppressing inflammation and apoptosis.

iPSCs chondrogenic differentiation for personalized regenerative medicine: a literature review.

Cartilage, an important connective tissue, provides structural support to other body tissues, and serves as a cushion against impacts throughout the body. Found at the end of the bones, cartilage decreases friction and averts bone-on-bone contact during joint movement. Therefore, defects of cartilage can result from natural wear and tear, or from traumatic events, such as injuries or sudden changes in direction during sports activities. Overtime, these cartilage defects which do not always produce immediate symptoms, could lead to severe clinical pathologies. The emergence of induced pluripotent stem cells (iPSCs) has revolutionized the field of regenerative medicine, providing a promising platform for generating various cell types for therapeutic applications. Thus, chondrocytes differentiated from iPSCs become a promising avenue for non-invasive clinical interventions for cartilage injuries and diseases. In this review, we aim to highlight the current strategies used for in vitro chondrogenic differentiation of iPSCs and to explore their multifaceted applications in disease modeling, drug screening, and personalized regenerative medicine. Achieving abundant functional iPSC-derived chondrocytes requires optimization of culture conditions, incorporating specific growth factors, and precise temporal control. Continual improvements in differentiation methods and integration of emerging genome editing, organoids, and 3D bioprinting technologies will enhance the translational applications of iPSC-derived chondrocytes. Finally, to unlock the benefits for patients suffering from cartilage diseases through iPSCs-derived technologies in chondrogenesis, automatic cell therapy manufacturing systems will not only reduce human intervention and ensure sterile processes within isolator-like platforms to minimize contamination risks, but also provide customized production processes with enhanced scalability and efficiency.

The Expression of a Subset of Aging and Antiaging Markers Following the Chondrogenic and Osteogenic Differentiation of Mesenchymal Stem Cells of Placental Origin.

Mesenchymal stem cells (MSCs) of placental origin hold great promise in tissue engineering and regenerative medicine for diseases affecting cartilage and bone. However, their utility has been limited by their tendency to undergo premature senescence and phenotypic drift into adipocytes. This study aimed to explore the potential involvement of a specific subset of aging and antiaging genes by measuring their expression prior to and following in vitro-induced differentiation of placental MSCs into chondrocytes and osteoblasts as opposed to adipocytes. The targeted genes of interest included the various LMNA/C transcript variants (lamin A, lamin C, and lamin A∆10), sirtuin 7 (SIRT7), and SM22α, along with the classic aging markers plasminogen activator inhibitor 1 (PAI-1), p53, and p16INK4a. MSCs were isolated from the decidua basalis of human term placentas, expanded, and then analyzed for phenotypic properties by flow cytometry and evaluated for colony-forming efficiency. The cells were then induced to differentiate in vitro into chondrocytes, osteocytes, and adipocytes following established protocols. The mRNA expression of the targeted genes was measured by RT-qPCR in the undifferentiated cells and those fully differentiated into the three cellular lineages. Compared to undifferentiated cells, the differentiated chondrocytes demonstrated decreased expression of SIRT7, along with decreased PAI-1, lamin A, and SM22α expression, but the expression of p16INK4a and p53 increased, suggesting their tendency to undergo premature senescence. Interestingly, the cells maintained the expression of lamin C, which indicates that it is the primary lamin variant influencing the mechanoelastic properties of the differentiated cells. Notably, the expression of all targeted genes did not differ from the undifferentiated cells following osteogenic differentiation. On the other hand, the differentiation of the cells into adipocytes was associated with decreased expression of lamin A and PAI-1. The distinct patterns of expression of aging and antiaging genes following in vitro-induced differentiation of MSCs into chondrocytes, osteocytes, and adipocytes potentially reflect specific roles for these genes during and following differentiation in the fully functional cells. Understanding these roles and the network of signaling molecules involved can open opportunities to improve the handling and utility of MSCs as cellular precursors for the treatment of cartilage and bone diseases.