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.

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/β-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-β3 enhancing cartilage-specific extracellular matrix (ECM) production and chondrogenic differentiation. The combination of Wnt3a and TGF-β3 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.

UNASSIGNED: 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.
UNASSIGNED: 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 β-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/β-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 β-catenin protein accumulation in articular cartilage, and that was further enhanced by combined treatment with rSMSC-EVs and ICA.
UNASSIGNED: Our findings highlight the promising potential of using combined treatment with ICA and rSMSC-EVs for promoting osteochondral repair.

Electrical stimulation (ES) is a widely discussed topic in the field of cartilage tissue engineering due to its ability to induce chondrogenic differentiation (CD) and proliferation. It shows promise as a potential therapy for osteoarthritis (OA). In this study, we stimulated mesenchymal stem cells (MSCs) incorporated into collagen hydrogel (CH) scaffolds, consisting of approximately 500,000 cells each, for 1 h per day using a 2.5 Vpp (119 mV/mm) 8 Hz sinusoidal signal. We compared the cell count, morphology, and CD on days 4, 7, and 10. The results indicate proliferation, with an increase ranging from 1.86 to 9.5-fold, particularly on day 7. Additionally, signs of CD were observed. The stimulated cells had a higher volume, while the stimulated scaffolds showed shrinkage. In the ES groups, up-regulation of collagen type 2 and aggrecan was found. In contrast, SOX9 was up-regulated in the control group, and MMP13 showed a strong up-regulation, indicating cell stress. In addition to lower stress levels, the control groups also showed a more spheroidic shape. Overall, scaffold-based ES has the potential to achieve multiple outcomes. However, finding the appropriate stimulation pattern is crucial for achieving successful chondrogenesis.

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.

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.

OBJECTIVE: The objective of this study was to provide a comprehensive review of the existing literature regarding the treatment of osteochondral lesions of the talus (OLT) using autologous matrix-induced chondrogenesis (AMIC), while also discussing the mid-long term functional outcomes, complications, and surgical failure rate.
METHODS: We searched Embase, PubMed, and Web of Science for studies on OLT treated with AMIC with an average follow-up of at least 2 years. Publication information, patient data, functional scores, surgical failure rate, and complications were extracted.
RESULTS: A total of 15 studies were screened and included, with 12 case series selected for meta-analysis and 3 non-randomized controlled studies chosen for descriptive analysis. The improvements in the Visual Analog Scale (VAS), the American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot, and Tegner scores at the last follow-up were (SMD = - 2.825, 95% CI - 3.343 to  - 2.306, P < 0.001), (SMD = 2.73, 95% CI 1.60 to 3.86, P < 0.001), (SMD = 0.85, 95% CI 0.5 to 1.2, P < 0.001) respectively compared to preoperative values. The surgery failure rate was 11% (95% CI 8-15%), with a total of 12 patients experiencing complications.
CONCLUSIONS: The use of AMIC demonstrates a positive impact on pain management, functional improvement, and mobility enhancement in patients with OLT. It is worth noting that the choice of stent for AMIC, patient age, and OLT size can influence the ultimate clinical outcomes. This study provides evidences supporting the safety and efficacy of AMIC as a viable treatment option in real-world medical practice.

BACKGROUND: Teratomas are a common type of germ cell tumor. However, only a few reports on their genomic constitution have been published. The study of teratomas may provide a better understanding of their stepwise differentiation processes and molecular bases, which could prove useful for the development of tissue-engineering technologies.
METHODS: In the present study, we analyzed the copy number aberrations of nine ovarian mature cystic teratomas using array comparative genomic hybridization in an attempt to reveal their genomic aberrations.
RESULTS: The many chromosomal aberrations observed on array comparative genomic hybridization analysis reveal the complex genetics of this tumor. Amplifications and deletions of large DNA fragments were observed in some samples, while amplifications of EVX2 and HOXD9-HOXD13 on 2q31.1, NDUFV1 on 11q13.2, and RPL10, SNORA70, DNASE1L1, TAZ, ATP6AP1, and GDI1 on Xq28 were found in all nine mature cystic teratomas.
CONCLUSIONS: Our results indicated that amplifications of these genes may play an important etiological role in teratoma formation. Moreover, amplifications of EVX2 and HOXD9-HOXD13 on 2q31.1, found on array comparative genomic hybridization, may help to explain the characteristics of teratomas in chondrogenesis and osteogenesis.

Articular cartilage damage still remains a major problem in orthopedical surgery. The development of tissue engineering techniques such as autologous chondrocyte implantation is a promising way to improve clinical outcomes. On the other hand, the clinical application of autologous chondrocytes has considerable limitations. Mesenchymal stromal cells (MSCs) from various tissues have been shown to possess chondrogenic differentiation potential, although to different degrees. In the present study, we assessed the alterations in chondrogenesis-related gene transcription rates and extracellular matrix deposition levels before and after the chondrogenic differentiation of MSCs in a 3D spheroid culture. MSCs were obtained from three different tissues: umbilical cord Wharton\'s jelly (WJMSC-Wharton\'s jelly mesenchymal stromal cells), adipose tissue (ATMSC-adipose tissue mesenchymal stromal cells), and the dental pulp of deciduous teeth (SHEDs-stem cells from human exfoliated deciduous teeth). Monolayer MSC cultures served as baseline controls. Newly formed 3D spheroids composed of MSCs previously grown in 2D cultures were precultured for 2 days in growth medium, and then, chondrogenic differentiation was induced by maintaining them in the TGF-β1-containing medium for 21 days. Among the MSC types studied, WJMSCs showed the most similarities with primary chondrocytes in terms of the upregulation of cartilage-specific gene expression. Interestingly, such upregulation occurred to some extent in all 3D spheroids, even prior to the addition of TGF-β1. These results confirm that the potential of Wharton\'s jelly is on par with adipose tissue as a valuable cell source for cartilage engineering applications as well as for the treatment of osteoarthritis. The 3D spheroid environment on its own acts as a trigger for the chondrogenic differentiation of MSCs.

Joint-resident chondrogenic precursor cells have become a significant therapeutic option due to the lack of regenerative capacity in articular cartilage. Progenitor cells are located in the superficial zone of the articular cartilage, producing lubricin/Prg4 to decrease friction of cartilage surfaces during joint movement. Prg4-positive progenitors are crucial in maintaining the joint\'s structure and functionality. The disappearance of progenitor cells leads to changes in articular hyaline cartilage over time, subchondral bone abnormalities, and the formation of ectopic ossification. Genetic labeling cell technology has been the main tool used to characterize Prg4-expressing progenitor cells of articular cartilage in vivo through drug injection at different time points. This technology allows for the determination of the origin of progenitor cells and the tracking of their progeny during joint development and cartilage damage. We endeavored to highlight the currently known information about the Prg4-producing cell population in the joint to underline the significance of the role of these cells in the development of articular cartilage and its homeostasis. This review focuses on superficial progenitors in the joint, how they contribute to postnatal articular cartilage formation, their capacity for regeneration, and the consequences of Prg4 deficiency in these cells. We have accumulated information about the Prg4+ cell population of articular cartilage obtained through various elegantly designed experiments using transgenic technologies to identify potential opportunities for further research.