Study of Telomere Length in Preimplanted Cultured Chondrocytes

Cartilage Defect Treatment Using High-Density Autologous Chondrocyte Implantation (HD-ACI)

Hyaline cartilage's inability to self-repair can lead to osteoarthritis and joint replacement. Various treatments, including cell therapy, have been developed for cartilage damage. Autologous chondrocyte implantation (ACI) is considered the best option for focal chondral lesions. In this article, we aimed to create a narrative review that highlights the evolution and enhancement of our chondrocyte implantation technique: High-Density-ACI (HD-ACI) Membrane-assisted Autologous Chondrocyte Implantation (MACI) improved ACI using a collagen membrane as a carrier. However, low cell density in MACI resulted in softer regenerated tissue. HD-ACI was developed to improve MACI, implanting 5 million chondrocytes per cm2, providing higher cell density. In animal models, HD-ACI formed hyaline-like cartilage, while other treatments led to fibrocartilage. HD-ACI was further evaluated in patients with knee or ankle defects and expanded to treat hip lesions and bilateral defects. HD-ACI offers a potential solution for cartilage defects, improving outcomes in regenerative medicine and cell therapy. HD-ACI, with its higher cell density, shows promise for treating chondral defects and advancing cartilage repair in regenerative medicine and cell therapy.

Autophagy and apoptosis: regulatory factors of chondrocyte phenotype transition in osteoarthritis

Osteoarthritis (OA) is the main pathogenic factor in diseases that cause joint deformities. As the main manifestation of the progress of OA, cartilage degradation has been closely associated with the degeneration of chondrocytes, which is induced by inflammatory factors and other trauma factors. Autophagy and apoptosis are the main mechanisms for cells to maintain homeostasis and play crucial roles in OA. Under the influence of external environmental factors (such as aging and injury), the metabolism of cells can be altered, which may affect the extent of autophagy and apoptosis. With the progression of OA, these changes can alter the cell phenotypes, and the cells of different phenotypes display distinct differences in morphology and function. In this review, we have summarized the alteration in cell metabolism, autophagy, and the extent of apoptosis during OA progression and its effects on the cell phenotypes to provide new ideas for further research on the mechanisms of phenotypic transition and therapeutic strategies so as to reverse the cell phenotypes.

Alterations in characteristics of canine articular chondrocytes in non-passaged long-term monolayer culture: Matter of differentiation, dedifferentiation and redifferentiation

This study investigated the effects of culture time on phenotype stability of canine articular chondrocytes (CACs) in non-passaged long-term monolayer culture. Third passage (P3) CACs isolated from four cartilage samples were seeded at three different initial seeding densities (0.2 × 10⁴, 1.0 × 10⁴ and 5.0 × 10⁴ cells/cm²) and maintained in monolayer condition up to 8 weeks without undergoing subculture after confluence. The characteristic changes of chondrocytes during the culture period were evaluated based on the cell morphology, cell proliferation, glycosaminoglycans (GAGs) content, DNA quantification, mRNA expression and ultrastructure of chondrocytes. Chondrocytes maintained under post-confluence condition exhibited a capability to grow and proliferate up to 4 weeks. Alcian blue staining and Dimethylmethylene blue (DMMB) assay revealed that the extracellular matrix (ECM) synthesis was increased in a time-dependent manner from 2 to 8 weeks. The chondrocyte mRNA expression profile was dramatically affected by prolonged culture time, with a significant downregulation of collagen type I, whereas the expression of collagen type II, aggrecan, Sox9 and matrix metalloproteinase 13 (MMP-13) were significantly upregulated. In addition, transmission electron microscopy (TEM) result indicated dilation of rough endoplasmic reticulum (RER) in these long-term monolayer cultured chondrocytes. These findings demonstrate that the chondrocytes phenotype could be partially redifferentiated through the spontaneous redifferentiation process in long-term cultures using standard culture medium without the addition of chondrogenic supplements or tissue-culture scaffolds.

Analytical Validation of Telomere Analysis Technology® for the High-Throughput Analysis of Multiple Telomere-Associated Variables

Background

A large number of studies have suggested a correlation between the status of telomeres and disease risk. High-throughput quantitative fluorescence in situ hybridization (HT Q-FISH) is a highly accurate telomere measurement technique that can be applied to the study of large cell populations. Here we describe the analytical performance testing and validation of Telomere Analysis Technology (TAT®), a laboratory-developed HT Q-FISH-based methodology that includes HT imaging and software workflows that provide a highly detailed view of telomere populations.

Methods

TAT was developed for the analysis of telomeres in peripheral blood mononuclear cells (PBMCs). TAT was compared with Terminal Restriction Fragment (TRF) length analysis, and tested for accuracy, precision, limits of detection (LOD) and specificity, reportable range and reference range.

Results

Using 6 different lymphocyte cell lines, we found a high correlation between TAT and TRF for telomere length (R² ≥ 0.99). The standard variation (assay error) of TAT was 454 base pairs, and the limit of detection of 800 base pairs. A standard curve was constructed to cover human median reportable range values and defined its lower limit at 4700 bp and upper limits at 14,400 bp. Using TAT, up to 223 telomere associated variables (TAVs) can be obtained from a single sample. A pilot, population study, of telomere analysis using TAT revealed high accuracy and reliability of the methodology.

Conclusions

Analytical validation of TAT shows that is a robust and reliable technique for the characterization of a detailed telomere profile in large cell populations. The combination of high-throughput imaging and software workflows allows for the collection of a large number of telomere-associated variables from each sample, which can then be used in epidemiological and clinical studies.