Role of insulin-transferrin-selenium in auricular chondrocyte proliferation and engineered cartilage formation in vitro

Insulin-transferrin-selenium promote formation of tissue-engineered vascular grafts in early stage of culture

To create tissue-engineered vascular grafts (TEVGs) in vitro, vascular smooth muscle cells (VSMCs) must function effectively and produce sufficient extracellular matrix (ECM) in a three-dimensional space. In this study, we investigated whether the addition of insulin-transferrin-selenium (ITS), a medium supplement, could enhance TEVG formation. PGA fabric was used as the scaffold, and 1% ITS was added to the medium. After two weeks, the tissues were examined using electron microscopy and staining. The ITS group exhibited a denser structure and increased collagen production. VSMCs were cultured in two dimensions with ITS and assessed for collagen production, cell growth, and glucose metabolism. The results showed that ITS supplementation increased collagen production, cell growth, glucose utilization, lactate production, and ATP levels. Furthermore, reducing the amount of fetal bovine serum (FBS) in the medium did not affect the TEVGs or VSMCs when ITS was present. In conclusion, ITS improves TEVG construction by promoting VSMCs growth and reducing the need for FBS.

Advancements in Chondrocyte 3-Dimensional Embedded Culture: Implications for Tissue Engineering and Regenerative Medicine

Cartilage repair necessitates regenerative medicine because of the unreliable healing mechanism of cartilage. To yield a sufficient number of cells for transplantation, chondrocytes must be expanded in culture. However, in 2D culture, chondrocytes tend to lose their distinctive phenotypes and functionalities after serial passage, thereby limiting their efficacy for tissue engineering purposes. The mechanism of dedifferentiation in 2D culture can be attributed to various factors, including abnormal nuclear strength, stress-induced mitochondrial impairment, chromatin remodeling, ERK-1/2 and the p38/mitogen-activated protein kinase (MAPK) signaling pathway. These mechanisms collectively contribute to the loss of chondrocyte phenotype and reduced production of cartilage-specific extracellular matrix (ECM) components. Chondrocyte 3D culture methods have emerged as promising solutions to prevent dedifferentiation. Techniques, such as scaffold-based culture and scaffold-free approaches, provide chondrocytes with a more physiologically relevant environment, promoting their differentiation and matrix synthesis. These methods have been used in cartilage tissue engineering to create engineered cartilage constructs for transplantation and joint repair. However, chondrocyte 3D culture still has limitations, such as low viability and proliferation rate, and also difficulties in passage under 3D condition. These indicate challenges of obtaining a sufficient number of chondrocytes for large-scale tissue production. To address these issues, ongoing studies of many research groups have been focusing on refining culture conditions, optimizing scaffold materials, and exploring novel cell sources such as stem cells to enhance the quality and quantity of engineered cartilage tissues. Although obstacles remain, continuous endeavors to enhance culture techniques and overcome limitations offer a promising outlook for the advancement of more efficient strategies for cartilage regeneration.

Phenolic acids prevent sex-steroid deficiency-induced bone loss and bone marrow adipogenesis in mice

Phenolic acids, such as hippuric acid (HA) and 3-(3-hydroxyphenyl) propionic acid (3-3-PPA), can be produced from microbiome digestion of polyphenols. Previously it was found that HA and 3-3-PPA facilitate bone formation and suppress bone resorption. However, the mechanism of action by which HA and 3-3-PPA protect bone from degeneration is currently unknown. In this report, we present that HA and 3-3-PPA suppression of bone resorption is able to ameliorate bone loss in an ovariectomy (OVX) osteopenic mouse model though not to the extent of Zoledronic acid (ZA). HA and 3-3-PPA treatments were shown to significantly decrease bone marrow adipocyte-like cell formation and inhibited gene expression of key adipogenesis regulator peroxisome proliferator activated receptor gamma (PPARγ) and lipoprotein lipase (Lpl) in bone from OVX mice. In addition, ChIP experiments showed that the association between PPARγ and Lpl promoter region in preadipocyte-like cells was significantly suppressed following HA or 3-3-PPA treatment. Contrasting HA and 3-3-PPA, ZA significantly increased TRAP activity in the area close to growth plate and significantly suppressed bone cell proliferation. These data suggest that phenolics acids such as HA or 3-3-PPA may prevent bone degeneration after OVX through suppression of inflammatory milieu in the bone.

Combined Transcriptomics and Metabolomics Identify Regulatory Mechanisms of Porcine Vertebral Chondrocyte Development In Vitro

Porcine body length is closely related to meat production, growth, and reproductive performance, thus playing a key role in the profitability of the pork industry. Cartilage development is critical to longitudinal elongation of individual vertebrae. This study isolated primary porcine vertebral chondrocytes (PVCs) to clarify the complex mechanisms of elongation. We used transcriptome and target energy metabolome technologies to confirm crucial genes and metabolites in primary PVCs at different differentiation stages (0, 4, 8, and 12 days). Pairwise comparisons of the four stages identified 4566 differentially expressed genes (DEGs). Time-series gene cluster and functional analyses of these DEGs revealed four clusters related to metabolic processes, cartilage development, vascular development, and cell cycle regulation. We constructed a transcriptional regulatory network determining chondrocyte maturation. The network indicated that significantly enriched transcription factor (TF) families, including zf-C2H2, homeobox, TF_bZIP, and RHD, are important in cell cycle and differentiation processes. Further, dynamic network biomarker (DNB) analysis revealed that day 4 was the tipping point for chondrocyte development, consistent with morphological and metabolic changes. We found 24 DNB DEGs, including the TFs NFATC2 and SP7. Targeted energy metabolome analysis showed that most metabolites were elevated throughout chondrocyte development; notably, 16 differentially regulated metabolites (DRMs) were increased at three time points after cell differentiation. In conclusion, integrated metabolome and transcriptome analyses highlighted the importance of amino acid biosynthesis in chondrocyte development, with coordinated regulation of DEGs and DRMs promoting PVC differentiation via glucose oxidation. These findings reveal the regulatory mechanisms underlying PVC development and provide an important theoretical reference for improving pork production.

Engineering bone-forming callus organoid implants in a xenogeneic-free differentiation medium

The field of tissue engineering aspires to provide clinically relevant solutions for patients through the integration of developmental engineering principles with a bottom-up manufacturing approach. However, the manufacturing of cell-based advanced therapy medicinal products is hampered by protocol complexity, lack of non-invasive critical quality controls, and dependency on animal-derived components for tissue differentiation. We investigate a serum-free, chemically defined, xeno- and lipid-free chondrogenic differentiation medium to generate bone-forming callus organoids. Our results show an increase in microtissue homogeneity during prolonged differentiation and the high quality of in vivo bone-forming organoids. The low protein content of the culture medium potentially allows for the monitoring of relevant secreted biomarkers as (critical) quality attributes. Together, we envisage that this xeno- and lipid-free chondrogenic medium is compatible with industrial scale-up and automation while facilitating the implementation of non-invasive imaging and the use of quality control parameters based on secreted biomarkers.

Transforming growth factor-β receptors mediates matrix degradation and abnormal hypertrophy in T-2 toxin-induced hypertrophic chondrocytes

This study investigated whether transforming growth factor-β receptor I (TGF-βRI) and TGF-βRII mediate matrix degradation and abnormal hypertrophy in T-2 toxin-induced hypertrophic chondrocytes. Hypertrophic chondrocytes were exposed to TGF-βRI and TGF-βRII binding inhibitor (GW788388) for 24 h prior to exposure to different concentrations of T-2 toxin (0, 10, 25, and 50 ng/mL for 48 h). Hypertrophic chondrocytes were assessed based on the expression of matrix-degrading and terminal differentiation-related genes and cell viability. Matrix metalloproteinases (MMPs, MMP-13, MMP-1, and MMP-9) were reduced in the GW788388+T-2 toxin group compared to the T-2 toxin group. The expression of terminal differentiation-related genes (MMP-2, MMP-10, and collagen X) was increased in hypertrophic chondrocytes in the inhibited groups compared to that in the T-2 toxin group. The survival rate of chondrocytes decreased significantly in a dose-dependent manner. GW788388 did not significantly block the reduced cell viability in hypertrophic chondrocytes exposed to T-2 toxin. The upregulated expression of TGF-βRI and TGF-βRII mediates the abnormal chondrocyte hypertrophy and extracellular matrix degeneration observed in T-2 toxin-induced hypertrophic chondrocytes.

A naringin-derived bioink enhances shape fidelity of 3D bioprinting and efficiency of cartilage defects repair

3D bioprinting is a major area of interest in health sciences for customized manufacturing, but lacks specific bioinks to enhance shape fidelity of 3D bioprinting and efficiency of tissue repair...

Self-assembling human skeletal organoids for disease modeling and drug testing

Skeletal conditions represent a considerable challenge to health systems globally. Barriers to effective therapeutic development include a lack of accurate preclinical tissue and disease models. Most recently, work was attempted to present a novel whole organ approach to modeling human bone and cartilage tissues. These self-assembling skeletal organoids mimic the cellular milieu and extracellular organization present in native tissues. Bone organoids demonstrated osteogenesis and micro vessel formation, and cartilage organoids showed evidence of cartilage development and maturation. Skeletal organoids derived from both bone and cartilage tissues yielded spontaneous polarization of their cartilaginous and bone components. Using these hybrid skeletal organoids, we successfully generated "mini joint" cultures, which we used to model inflammatory disease and test Adenosine (A_2A ) receptor agonists as a therapeutic agent. The work and respective results indicated that skeletal organoids can be an effective biological model for tissue development and disease as well as to test therapeutic agents.

Subcutaneous Regeneration of Engineered Cartilage: A Comparison of Cell Sheets and Chondrocyte-Scaffold Constructs in a Porcine Model

BACKGROUND

Stable cartilage regeneration in immunocompetent large animals remains a bottleneck problem that restricts clinical application. The inflammation elicited by degradation products of scaffolds has a decisive influence on cartilage formation. Although prolonged preculture in vitro could form mature engineered cartilage and allow sufficient degradation of scaffolds, the inflammatory reaction was still observed. This study explored the feasibility of using chondrocyte sheet technology to regenerate stable cartilage in the subcutaneous environment with a pig model.

METHODS

Passage 1 chondrocytes were used to form cell sheets by high-density culture. As a control, chondrocytes were seeded onto polyglycolic acid/polylactic acid scaffolds for 6 and 12 weeks' in vitro preculture, respectively. Then, they were autologously implanted subcutaneously into pigs for 2, 8, and 24 weeks. Gross view, histologic staining, and biochemical and biomechanical characteristics were evaluated.

RESULTS

With prolonged culture in vitro, relatively homogeneous engineered cartilages were formed with less scaffold residue. However, the chondrocyte-polyglycolic acid/polylactic acid group still encountered severe inflammation and inferior cartilage formation at 2 and 8 weeks in vivo. The engineered cartilage with cell sheet technique exhibited a relatively more stable and mature tissue structure without obvious inflammatory response at 24 weeks in vivo, which was similar to the native auricular cartilage.

CONCLUSIONS

The chondrocyte sheet technique could successfully regenerate mature and stable engineered cartilages in pig models. It is possibly an effective method of repairing cartilage defects in the clinic that uses regenerated substitutes derived from autologous cell sheets.

Investigating the role of culture conditions on hypertrophic differentiation in human cartilage endplate cells

Cartilage endplate degeneration/calcification has been linked to the onset and progression of intervertebral disc degeneration and there is a critical need to understand mechanisms, such as hypertrophic differentiation, of cartilage endplate degeneration/calcification to inform treatment strategies for discogenic back pain. In vitro cell culture conditions capable of inducing hypertrophic differentiation are used to study pathophysiological mechanisms in articular chondrocytes, but culture conditions capable of inducing a hypertrophic cartilage endplate cell phenotype have yet to be explored. The goal of this study was to investigate the role of culture conditions capable of inducing hypertrophic differentiation in articular chondrocytes on hypertrophic differentiation in human cartilage endplate cells. Isolated human cartilage endplate cells were cultured as pellets for 21 days at either 5% O₂ (physiologic for cartilage) or 20.7% O₂ (hyperoxic) and treated with 10% fetal bovine serum or Wnt agonist, two stimuli used to induce hypertrophic differentiation in articular chondrocytes. Cartilage endplate cells did not exhibit a hypertrophic cell morphology in response to fetal bovine serum or Wnt agonist but did display other hallmarks of chondrocyte hypertrophy and degeneration such as hypertrophic gene and protein expression, and a decrease in healthy proteoglycans and an increase in fibrous collagen accumulation. These findings demonstrate that cartilage endplate cells take on a degenerative phenotype in response to hypertrophic stimuli in vitro, but do not undergo classical changes in morphology associated with hypertrophic differentiation regardless of oxygen levels, highlighting potential differences in the response of cartilage endplate cells versus articular chondrocytes to the same stimuli.

Tissue Engineering Strategies for Auricular Reconstruction

Simulating natural characteristics and aesthetics in reconstructed ears has provided a complex 3-dimensional puzzle for those treating patients with microtia. Costochondral grafts remain the gold standard for autologous reconstruction. However, other options such as Medpor and prosthetics are indicated depending on patient circumstances and personal choice. Research into tissue engineering offers an alternative method to a traditional surgical approach that may reduce donor-site morbidity. However, tissue engineering for microtia reconstruction brings new challenges such as cell sourcing, promotion of chondrogenesis, scaffold vascularization, and prevention of scaffold contraction. Advancements in 3D printing, nanofiber utilization, stem cell technologies, and decellularization techniques have played significant roles in overcoming these challenges. These recent advancements and reports of a successful clinical-scale study in an immunocompetent animal suggest a promising outlook for future clinical application of tissue engineering for auricular reconstruction.

Bone marrow extract as a growth supplement for human iliac apophyseal chondrocyte culture

Background & objectives:

Human bone marrow is rich in various growth factors which may support the chondrocyte growth. This study was conducted to compare the culture characteristics of human growth plate chondrocyte in foetal bovine serum (FBS) and human autologous bone marrow extract (BME) in monolayer culture.

Methods:

Iliac crest apophyseal cartilage was harvested from four donors, aged between two and nine years, undergoing hip surgery. Chondrocytes were propagated under two culture conditions, with 10 per cent FBS and 10 per cent autologous BME harvested from the same donors. Cells were harvested at 7, 14 and 21 days to assess viability, morphology, cell count and immunocytochemistry.

Results:

With an initial seeding density of 2500 cells/cm², the average yield in monolayer cultured with FBS was 3.35 × 10⁵, 5.9 × 10⁵, 14.1 × 10⁵ and BME was 0.66 × 10⁵, 1.57 × 10⁵ and 3.48 × 10⁵ at 7, 14 and 21 days, respectively. Viability was 98.21 per cent with FBS and 97.45 per cent with BME at 21 days. In BME supplemented cultures, hyaline phenotype was maintained up to 21 days. The yield was higher in the FBS supplemented group; however, the phenotype could not be maintained by the FBS group as long as BME group.

Interpretation & conclusions:

Autologous BME was found to be a safer alternative to FBS for human studies. BME could maintain the hyaline phenotype for a longer time. Ways to enhance the cell yield needs to be explored in future studies.

Differentiating Chondrocytes from Peripheral Blood-derived Human Induced Pluripotent Stem Cells

In this study, we used peripheral blood cells (PBCs) as seed cells to produce chondrocytes via induced pluripotent stem cells (iPSCs) in an integration-free method. Following embryoid body (EB) formation and fibroblastic cell expansion, the iPSCs are induced for chondrogenic differentiation for 21 days under serum-free and xeno-free conditions. After chondrocyte induction, the phenotypes of the cells are evaluated by morphological, immunohistochemical, and biochemical analyses, as well as by the quantitative real-time PCR examination of chondrogenic differentiation markers. The chondrogenic pellets show positive alcian blue and toluidine blue staining. The immunohistochemistry of collagen II and X staining is also positive. The sulfated glycosaminoglycan (sGAG) content and the chondrogenic differentiation markers COLLAGEN 2 (COL2), COLLAGEN 10 (COL10), SOX9, and AGGRECAN are significantly upregulated in chondrogenic pellets compared to hiPSCs and fibroblastic cells. These results suggest that PBCs can be used as seed cells to generate iPSCs for cartilage repair, which is patient-specific and cost-effective.

Selenium Reduces Early Signs of Tumor Necrosis Factor Alpha-Induced Meniscal Tissue Degradation

Meniscal integrity is a prerequisite for sustained knee joint health and prevention of meniscal degeneration is a main research goal. Cartilage-protective effects of selenium have been described, but little is known about the impact on the meniscus. We therefore investigated the influence of sodium selenite on meniscal explants under tumor necrosis factor-alpha (TNFα)-stimulated proinflammatory conditions. Meniscal explant disks (3 mm diameter × 1 mm thickness) were isolated from 2-year-old cattle and incubated with TNFα (10 ng/ml) and sodium selenite (low dose, LoD 6.7 ng/ml as being found in Insulin-Transferrin-Selenium medium supplements, ITS; medium-dose, MeD 40 ng/ml described as physiological synovial concentration; high dose, HiD 100 ng/ml described as optimal serum concentration). After 3 days of culture glycosaminoglycan (GAG) release (DMMB assay), nitric oxide (NO) production (Griess assay), gene expression of matrix-degrading enzymes (quantitative RT-PCR), and apoptosis rate were determined. TNFα led to a significant raise of GAG release and NO production. LoD and MeD selenite significantly reduced the TNFα-induced GAG release (by 83, 55 %, respectively), NO production (by 59, 40 %, respectively), and apoptosis (by 68, 39 %, respectively). LoD and MeD selenite showed a tendency to reduce the TNFα-mediated increase of inducible NO-synthase (iNOS) levels, LoD selenite furthermore matrix metalloproteinase (MMP)-3 transcription levels and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-4 levels. LoD and less pronounced MeD selenite show a substantial impact on the early meniscal inflammatory response. To our knowledge this is the first study showing the protective influence of selenium on meniscal tissue maintenance. To understand the superior potency of low-dose selenium on molecular level future studies are needed.

Importance of Floating Chondrons in Cartilage Tissue Engineering

BACKGROUND

Dedifferentiation of chondrocytes remains a major problem for cartilage tissue engineering. Chondrocytes loss differentiated phenotype in in vitro culture that is undesired for repair strategies. The chondrocyte is surrounded by a pericellular matrix (PCM), together forming the chondron. PCM has a positive effect on the maintenance of chondrocyte phenotype during culture in comparison to uncovered chondrocyte. Studies suggest that the PCM influence on functional properties of the chondrocytes. However there is no study to show gene expression phenotype differences between round chondron and fibroblastic chondrocytes. We aimed to investigate the effect of pericellular matrix in maintaining of chondrogenic gene expression to solve dedifferentiation problem of chondrocyte.

METHODS

In this study enzymatically isolated chondrons were cultured for 7 days. Morphology of chondrons were assessed by microscopic examination. Chondrogenic gene expression of Sox9, aggrecan (AGG), cartilage oligomeric matrix protein (COMP), Link protein and chondro-osteogenic gene expression (Runx2, Col1, Col 10 and MMP13) of attached and float chondrons were assessed by real time RT PCR.

RESULTS

Microscopic observation showed that round shape of chondron observed at day 7 in floating chondrocytes. Gene expression results showed that attached chondrons significantly dedifferentiated by low gene expression of Sox9 and COMP and high MMP13 versus floating cells.

CONCLUSION

Our results showed that PCM of chondrocyte could restore differentiated state of chondrocytes at day 7. Using unattached form of chondron in cartilage tissue PCM in maintenance of chondrogenic gene expression engineering could be a novel method to solve dedifferentiation problem of chondrocyte.

Cell-based tissue engineering strategies used in the clinical repair of articular cartilage

One of the most important issues facing cartilage tissue engineering is the inability to move technologies into the clinic. Despite the multitude of current research in the field, it is known that 90% of new drugs that advance past animal studies fail clinical trials. The objective of this review is to provide readers with an understanding of the scientific details of tissue engineered cartilage products that have demonstrated a certain level of efficacy in humans, so that newer technologies may be developed upon this foundation. Compared to existing treatments, such as microfracture or autologous chondrocyte implantation, a tissue engineered product can potentially provide more consistent clinical results in forming hyaline repair tissue and in filling the entirety of the defect. The various tissue engineering strategies (e.g., cell expansion, scaffold material, media formulations, biomimetic stimuli, etc.) used in forming these products, as collected from published literature, company websites, and relevant patents, are critically discussed. The authors note that many details about these products remain proprietary, not all information is made public, and that advancements to the products are continuously made. Nevertheless, by understanding the design and production processes of these emerging technologies, one can gain tremendous insight into how to best use them and also how to design the next generation of tissue engineered cartilage products.

Cell-based tissue engineering strategies used in the clinical repair of articular cartilage

One of the most important issues facing cartilage tissue engineering is the inability to move technologies into the clinic. Despite the multitude of current research in the field, it is known that 90% of new drugs that advance past animal studies fail clinical trials. The objective of this review is to provide readers with an understanding of the scientific details of tissue engineered cartilage products that have demonstrated a certain level of efficacy in humans, so that newer technologies may be developed upon this foundation. Compared to existing treatments, such as microfracture or autologous chondrocyte implantation, a tissue engineered product can potentially provide more consistent clinical results in forming hyaline repair tissue and in filling the entirety of the defect. The various tissue engineering strategies (e.g., cell expansion, scaffold material, media formulations, biomimetic stimuli, etc.) used in forming these products, as collected from published literature, company websites, and relevant patents, are critically discussed. The authors note that many details about these products remain proprietary, not all information is made public, and that advancements to the products are continuously made. Nevertheless, by understanding the design and production processes of these emerging technologies, one can gain tremendous insight into how to best use them and also how to design the next generation of tissue engineered cartilage products.

Insulin-transferrin-selenium as an alternative to foetal serum for epidermal equivalents

OBJECTIVE

Organotypic skin models are powerful tools for research in development, ageing and diseases. They have become more and more complex with the use of multiple cell types. This requires a culture medium adapted to optimize the development of such in vitro skin. Foetal bovine serum (FBS) is the most complete supplement in existence at the moment, providing at once growth factors, vitamins, hormones and other circulating compounds. However, this cocktail suffers from batch variability and its animal origin is ethically questionable. More importantly, its biological activities may interfere with the study of certain signalling pathways. Here, we present a strategy for constructing an epidermal equivalent using a defined culture medium without serum.

METHODS

An epidermal equivalent was constructed with primary human keratinocytes cultured using an insulin-transferrin-selenium (ITS) medium. Determination of steady-state gene expression levels and the immunohistological characterization of keratinocyte markers were performed to compare the ITS medium condition with a reference model, where keratinocytes were co-cultured with fibroblasts in the presence of FBS.

RESULTS

The data show that the ITS medium promoted the expression of keratinocyte proliferation and differentiation markers at the protein and transcript levels in a similar way to that of the reference model.

CONCLUSION

We show that culture using the ITS medium appears as a viable replacement for FBS in the construction of epidermal equivalents, opening the way to signal transduction studies.