Decreased length of telomeric DNA sequences and increased numerical chromosome aberrations in human osteoarthritic chondrocytes

Aging and the emerging role of cellular senescence in osteoarthritis

OBJECTIVE

The correlation between age and incidence of osteoarthritis (OA) is well known but the causal mechanisms involved are not completely understood. This narrative review summarizes selected key findings from the past 30 years that have elucidated key aspects of the relationship between aging and OA.

METHODS

The peer-reviewed English language literature was searched on PubMed using keywords including senescence, aging, cartilage, and osteoarthritis, for original studies and reviews published from 1993 to 2023 with a major focus on more recent studies. Manuscripts most relevant to aging and OA that examined one or more of the hallmarks of aging were selected for further review.

RESULTS

All proposed hallmarks of aging have been observed in articular cartilage and some have also been described in other joint tissues. Hallmarks include genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, disabled macroautophagy, chronic inflammation, and dysbiosis. There is evidence that these age-related changes contribute to the development of OA in part by promoting cellular senescence. Senescence may therefore serve as a downstream mediator that connects numerous aging hallmarks to OA, likely through the senescence-associated secretory phenotype that is characterized by increased production of proinflammatory cytokines and matrix metalloproteinases.

CONCLUSIONS

Progress over the past 30 years has provided the foundation for emerging therapies, such as senolytics and senomorphics, that hold promise for OA disease modification. Mechanistic studies utilizing physiologically-aged animals and cadaveric human joint tissues will be important for continued progress.

Sex-specific differences in telomere length of patients with primary knee osteoarthritis

Accelerated telomere shortening is associated with age-related diseases, including osteoarthritis (OA). We aimed to determine the relative telomere length (TL) in leukocytes and cartilage of patients with primary knee OA and to investigate factors that may affect TL in OA. Relative TL measurements were performed using qPCR in leukocytes of 612 individuals (310 patients with primary knee OA undergoing total knee arthroplasty (TKA) and 302 unaffected controls). We also analysed cartilage in 57 of the 310 OA patients, measuring relative TL in severely affected and less affected (control) cartilage collected from the same knee. Cartilage TLs were compared to leukocyte TLs in all 57 patients. A significant sex-by-disease-status interaction was found in regard to relative TL. Controlling for age, the average difference of leukocyte TL between female OA patients versus female controls was 0.217 units greater than that between male OA patients versus male controls (95% CI; [0.014, 0.421]). Relative TL comparison of severely and less affected cartilage samples from the same joint showed attrition of telomeres corresponding to disease severity (0.345 mean TL difference with 95% CI of [0.151, 0.539]) in the joint. We also noted that both severely and less affected cartilage had shorter telomeres than leukocytes collected from the same patient. Severe and moderate pain in OA patients was associated with shorter TL in leukocytes, but there was no association with depression or smoking in leukocytes and cartilage. Our study indicates that sex is an important factor in OA contributing to leukocyte and cartilage TL and that pain in OA shows an inverse association only with leukocyte TL.

Telomere Length and Risk of Incident Fracture and Arthroplasty: Findings From UK Biobank

We investigated independent associations between telomere length and risk of fracture and arthroplasty in UK Biobank participants. Leukocyte telomere length (LTL) was measured in baseline samples using a validated polymerase chain reaction (PCR) method. We used, in men and women separately, Cox proportional hazards models to calculate the hazard ratio (HR) for incident fracture (any, osteoporotic) or arthroplasty (hip or knee) over 1,186,410 person-years of follow-up. Covariates included age, white cell count, ethnicity, smoking, alcohol, physical activity, and menopause (women). In further analyses we adjusted for either estimated bone mineral density (eBMD) from heel quantitative ultrasound, handgrip strength, gait speed, total fat mass (bioimpedance), or blood biomarkers, all measured at baseline (2006-2010). We studied 59,500 women and 51,895 men, mean ± standard deviation (SD) age 56.4 ± 8.0 and 57.0 ± 8.3 years, respectively. During follow-up there were 5619 fractures; 5285 hip and 4261 knee arthroplasties. In confounder-adjusted models, longer LTL was associated with reduced risk of incident knee arthroplasty in both men (HR/SD 0.93; 95% confidence interval [CI], 0.88-0.97) and women (0.92; 95% CI, 0.88-0.96), and hip arthroplasty in men (0.91; 95% CI, 0.87-0.95), but not women (0.98; 95% CI, 0.94-1.01). Longer LTL was weakly associated with reduced risk of any incident fracture in women (HR/SD 0.96; 95% CI, 0.93-1.00) with less evidence in men (0.98; 95% CI, 0.93-1.02). Associations with incident outcomes were not materially altered by adjustment for heel eBMD, grip strength, gait speed, fat mass, or blood biomarker measures. In this, the largest study to date, longer LTL was associated with lower risk of incident knee or hip arthroplasty, but only weakly associated with lower risk of fracture. The relative risks were low at a population level, but our findings suggest that common factors acting on the myeloid and musculoskeletal systems might influence later life musculoskeletal outcomes. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Genetically Predicted Longer Telomere Length May Reduce Risk of Hip Osteoarthritis

Objective: This two-sample Mendelian randomization (MR) study aimed to examine the potential causal association of telomere length (TL) with the risk of osteoarthritis (OA).

Method: The summary-level data for OA was derived from the United Kingdom Biobank cohort, including 50,508 individuals of European descent. Eighteen single nucleotide polymorphisms associated with TL were identified as instrumental variables from the most up-to-date TL genome-wide association study (GWAS) involving over 78,592 individuals of European descent. Based on the GWASs data, MR was performed using established statistical analysis methods including the inverse variance weighted, weighted median, MR-Egger, and MR pleiotropy residual sum and outlier.

Results: Genetically determined TL was not associated with the risk of total OA (IVW odds ratio [OR] = 1.00, 95% confidence interval [CI] = 0.83, 1.21). In subgroup analyses stratified by OA site, no evidence in favor of association between genetically determined TL and knee OA was found (IVW OR = 1.18, 95% CI = 0.89, 1.58). However, using WM method, we observed a limited protective effect of longer TL on the risk of hip OA (OR = 0.60, 95% CI = 0.36–0.99), whereas the results of the IVW (p = 0.931) and MR-PRESSO (p = 0.932) showed that TL had no effect on hip OA.

Conclusions: This study does not support a causal association between TL and total OA. A potential protective association between longer TL and hip OA, though possible, remains less certain.

Chondrocyte Aging: The Molecular Determinants and Therapeutic Opportunities

Osteoarthritis (OA) is a joint degenerative disease that is an exceedingly common problem associated with aging. Aging is the principal risk factor for OA, but damage-related physiopathology of articular chondrocytes probably drives the mechanisms of joint degeneration by a progressive decline in the homeostatic and regenerative capacity of cells. Cellular aging is the manifestation of a complex interplay of cellular and molecular pathways underpinned by transcriptional, translational, and epigenetic mechanisms and niche factors, and unraveling this complexity will improve our understanding of underlying molecular changes that affect the ability of the articular cartilage to maintain or regenerate itself. This insight is imperative for developing new cell and drug therapies for OA disease that will target the specific causes of age-related functional decline. This review explores the key age-related changes within articular chondrocytes and discusses the molecular mechanisms that are commonly perturbed as cartilage ages and degenerates. Current efforts and emerging potential therapies in treating OA that are being employed to halt or decelerate the aging processes are also discussed.

Mitochondrial DNA from osteoarthritic patients drives functional impairment of mitochondrial activity: a study on transmitochondrial cybrids

With the redefinition of osteoarthritis (OA) and the understanding that the joint behaves as an organ, OA is now considered a systemic illness with a low grade of chronic inflammation. Mitochondrial dysfunction is well documented in OA and has the capacity to alter chondrocyte and synoviocyte function. Transmitochondrial cybrids are suggested as a useful cellular model to study mitochondrial biology in vitro, as they carry different mitochondrial variants with the same nuclear background. The aim of this work was to study mitochondrial and metabolic function of cybrids with mitochondrial DNA from healthy (N) and OA donors. In this work, the authors demonstrate that cybrids from OA patients behave differently from cybrids from N donors in several mitochondrial parameters. Furthermore, OA cybrids behave similarly to OA chondrocytes. These results enhance our understanding of the role of mitochondria in the degeneration process of OA and present cybrids as a useful model to study OA pathogenesis.

Relationship Between the Dynamics of Telomere Loss in Peripheral Blood Leukocytes From Knee Osteoarthritis Patients and Mitochondrial DNA Haplogroups

OBJECTIVE

To evaluate the evolution of telomere length from peripheral blood leukocytes (PBLs) in subjects from the Osteoarthritis Initiative (OAI) cohort in relation to the incidence of osteoarthritis (OA), and to explore its possible interactive influence with the mitochondrial DNA (mtDNA) haplogroup.

METHODS

Dynamics of telomere sequence loss were quantified in PBLs from initially healthy individuals (without symptoms or radiological signs), 78 carrying the mtDNA cluster HV, and 47 with cluster JT, from the OAI, during a 72-month follow-up period. The incidence of knee OA during this period (n = 39) was radiographically established when Kellgren-Lawrence (KL) score increased from < 2 at recruitment, to ≥ 2 at the end of 72 months of follow-up. Multivariate analysis using binary logistic regression was performed to assess PBL telomere loss and mtDNA haplogroups as associated risk factors of incidence of knee OA.

RESULTS

Carriers of cluster HV showed knee OA incidence twice that of the JT carriers (n = 30 vs 9). The rate of PBL telomere loss was higher in cluster HV carriers and in individuals with incident knee OA. Multivariate analysis showed that the dynamics of PBL telomere shortening can be a consistent risk marker of knee OA incidence. Subjects with nonincident knee OA showed a slower telomere loss than those with incident knee OA; the difference was more significant in carriers of cluster JT than in HV.

CONCLUSION

An increased rate of telomere loss in PBLs may reflect a systemic accelerated senescence phenotype that could be potentiated by the mitochondrial function, increasing the susceptibility of developing knee OA.

Common risk factors and therapeutic targets in obstructive sleep apnea and osteoarthritis: An unexpectable link?

Osteoarthritis (OA) and Obstructive Sleep Apnea (OSA) are two highly prevalent chronic diseases for which effective therapies are urgently needed. Recent epidemiologic studies, although scarce, suggest that the concomitant occurrence of OA and OSA is associated with more severe manifestations of both diseases. Moreover, OA and OSA share risk factors, such as aging and metabolic disturbances, and co-morbidities, including cardiovascular and metabolic diseases, sleep deprivation and depression. Whether this coincidental occurrence is fortuitous or involves cause-effect relationships is unknown. This review aims at collating and integrating present knowledge on both diseases by providing a brief overview of their epidemiology and pathophysiology, analyzing current evidences relating OA and OSA and discussing potential common mechanisms by which they can aggravate each other. Such mechanisms constitute potential therapeutic targets whose pharmacological modulation may provide more efficient ways of reducing the consequences of OA and OSA and, thus, lessen the huge individual and social burden that they impose.

Telomere shortening is associated with poor physical performance in knee osteoarthritis

Telomere length is a hallmark characteristic of ageing and age-related diseases. Osteoarthritis (OA) is the most common cause of joint pain and physical disability in the elderly. Previous studies have revealed the role of telomere shortening in OA; however, the relationship between telomere length, muscle strength and physical performance in knee OA patients remains unknown. The aim of the present study was to investigate the association of telomere length and physical performance in patients with knee OA. A total of 202 patients with knee OA and 60 healthy controls were enrolled in the study. The quality of life was assessed using Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index and Short Form Health Survey. The skeletal muscle mass was examined using bioelectrical impedance analysis, while the muscle strength was analyzed using hand grip force and isometric knee extension force. The physical performance of patients with knee OA was also investigated using gait speed, Timed up and go test (TUGT), Sit to stand test and 6-min walk test (6MWT). Blood leukocyte relative telomere length (RTL) was assessed using real time quantitative PCR. The mean blood leukocyte RTL in knee OA subjects was significantly lower compared with healthy controls (P<0.001). Knee OA patients with RTL values in the lowest quartile had a slow gait speed (P=0.006) and prolonged TUGT time (P=0.03). Multivariate regression analyses and multiple logistic regression analyses adjusted for age, sex, waist circumference, body mass index, fat mass, skeletal muscle index and the total WOMAC demonstrated that gait speed, TUGT and 6MWT were associated with longer RTL (P-trend<0.05). These findings suggested that poorer physical performance was associated with shorter RTL. Therefore, leukocyte telomere length and physical performance tests, especially gait speed, TUGT and 6MWT, could predict the health status and quality of life in patients with knee OA.

Telomere length and telomerase activity in osteoporosis and osteoarthritis

Osteoarthritis (OA) and osteoporosis (OP) are associated skeletal pathologies and have as a distinct feature the abnormal reconstruction of the subchondral bone. OA and OP have been characterized as age-related diseases and have been associated with telomere shortening and altered telomerase activity (TA). This review discusses the role of telomeres and telomerase in OA and OP pathologies and focuses on the usability of telomere length (TL) and the rate of telomere shortening as potential disease biomarkers. A number of studies have demonstrated that telomere shortening may contribute to OA and OP as an epigenetic factor. Therefore, it has been claimed that the measurement of TL of chondrocytes and/or peripheral blood cells may be an appropriate marker for the evaluation of the progression of these diseases. However, there is a need to be perform further studies with larger cohorts, with the aim of obtaining objective results and a better understanding of the association between TL, inflammation and aging, in order to provide further insight into the pathophysiology of degenerative joint diseases.

Leukocyte Telomere Length in Patients with Radiographic Knee Osteoarthritis

Relative mean telomere sequence amount was determined by quantitative PCR (qPCR) of peripheral blood leukocyte (PBL) samples obtained at recruitment (n = 310) from individuals from the Osteoarthritis (OA) Initiative consortium. Knees were radiologically evaluated according to the Kellgren-Lawrence (KL) score, ranging from 0 to 4, considering a KL grade ≥ 2 as radiographic evidence of OA (n = 124). Telomere size decreased as baseline KL score increased, being significantly shorter in subjects with KL ≥2 (Mann-Whitney U-test, P < 0.0001). PBL telomere size was also associated with age, hypertension, body mass index (BMI) and waist circumference. Nevertheless, logistic regression analysis showed that PBL telomere size was a consistent risk factor for concurrent knee OA, independent of these health parameters. Shorter PBL telomeres may indicate a premature aging status which enhances chondrocyte senescence and degenerative joint disease. Environ. Mol. Mutagen. 60:298-301, 2019. © 2018 Wiley Periodicals, Inc.

Study of Telomere Length in Preimplanted Cultured Chondrocytes

DESIGN

In the process of cell division, the extremes of the eukaryotic chromosomes are progressively shortening, and this phenomenon is related to cell degeneration and senescence. The treatment of cartilage lesions with autologous chondrocytes implies that cells proliferate in an artificial environment. We have studied the viability of cultured chondrocytes after measurement of their telomere length before implantation.

METHODS

Articular cartilage biopsies (B1, B2, and B3) were obtained from 3 patients (2 males and 1 female) with knee cartilage defects, who were going to be treated with chondrocyte implantation. Chondrocytes were cultured in DMEM with autologous serum. After the third passage, an aliquot of 1 million cells was removed to estimate the telomere length and the remaining cells were implanted. Telomere length was measured by quantitative fluorescent in situ hybridization (Q-FISH). Patients' clinical outcome was determined preoperatively, and 12 and 24 months postimplantation with the International Knee Documentation Committee (IKDC) questionnaire.

RESULTS

After chondrocyte implantation, IKDC score doubled at 12 and 24 months with regard to the basal value. After 3 passages, chondrocytes were cultured for a mean of 45.67 days, the mean duplication time being 4.53 days and the mean number of cell divisions being 10.04 during the culture period. The 20th percentile of telomere lengths were 6.84, 6.96, and 7.06 kbp and the median telomere lengths 10.30, 10.47, and 10.73 kbp, respectively. No significant correlation was found between IKDC score and telomere length.

CONCLUSION

Culturing autologous chondrocytes for implantation is not related to cell senescence in terms of telomere length.

Incident hand OA is strongly associated with reduced peripheral blood leukocyte telomere length

OBJECTIVE

To evaluate the relationship of telomere length to the prevalence and incidence of hand osteoarthritis in a longitudinal cohort.

DESIGN

We conducted a cross-sectional and longitudinal analysis of data from a subset of participants in the Osteoarthritis Initiative (OAI) recruited between February 2004 and May 2006. 274 individuals were eligible for the study based on availability of both baseline and 48-month hand radiographs and peripheral blood leucocyte telomere length data. Mean telomere length of peripheral blood leukocytes (PBL)s from the DNA samples was determined using a validated quantitative polymerase chain reaction (PCR)-based assay, and hand radiographs were analyzed and graded using the Kellgren-Lawrence scale.

RESULTS

In joint -level analyses, prevalent Interphalangeal Joint Osteoarthritis (IPJOA) was significantly associated with PBL telomere length in the baseline sample in unadjusted analyses (RR = 2.84; 95% CI:0.87-9.29) or in models adjusted for age, sex, and body mass index (aRR = 1.10; 95% CI: 0.96-1.27). The association in crude and adjusted analyses appeared slightly stronger with incident IPJOA, especially in the subset with normal hands at baseline (aRR = 1.62; 95% CI: 1.02-2.57). PBL telomere length was also associated with prevalent HOA at baseline (significant in unadjusted analysis: RR = 1.22; 95% CI 1.06-1.42), but not after adjusting for covariates: aRR = 1.12; 95% CI: 0.96-1.30). The magnitude of association was stronger for incident HOA, especially incident symptomatic HOA (aRR = 1.53; 95% CI: 1.09-2.15).

CONCLUSIONS

In summary, the results of this exploratory analysis are confirmatory of previous work showing a cross-sectional relationship between telomere length and HOA and add to the field by demonstrating an even stronger association with incident IPJOA, both radiographic and symptomatic.

[Genetic polymorphism of cytogenetic effects of radon bath therapy in the patients presenting with gonosteoarthritis of different etiology based at the Belokurikha health resort]

BACKGROUND

Borrelia infection is known to develop as a result of the bites of the ixodid ticks while the extremely difficult working conditions and low temperatures contribute to the development of chronic gonosteoarthritis (CGA) associated with ixodid tick-borne borreliosis (ITB) in the residents of the northern part of Siberia.

AIM

The objective of the present study was to elucidate the frequency of occurrence of the synovial cells in the knee joints exhibiting the cytogenetic abnormalities with special reference to trisomy of chromosome 7 and the glutathione-S-transferase (GSTM1) gene polymorphism in the residents of the northern part of Siberia presenting with Lyme borreliosis (LB) whose genotype contains some alleles of the GSTM1 gene before and after the treatment of LB-associated CGA with the use of the radon bath therapy. The secondary objective was to compare the respective characteristics and the results of the treatment with those in the patients with post-traumatic gonosteoarthritis (PTGA) and to evaluate the influence of the above abnormalities on the severity of CGA.

MATERIAL AND METHODS

The study included 69 patients having gonosteoarthritis associated with ixodid tick-borne borreliosis and residing in the northern areas of Siberia; in addition, 52 other individuals presenting with post-traumatic CGA made up the control group. The synovial cells of the knee joints were obtained from all the participants of the study for their culturing, making preparations, and analyzing chromosomal aberrations. The polymorphism of the GSTM1 gene was investigated with the use of the real-time polymerase chain reaction.

RESULTS

The frequency of cytogenetic abnormalities in the synovial cells obtained from the group of patients presenting with LB-associated CGA who were the carriers of the homozygous mutant genotype GSTM1(0/0) was significantly higher than that in the patients having the normal genotype GSTM1(+) before the course of radon bath therapy. This treatment resulted in a significant decrease of the severity of pain syndrome and the improvement of the locomotor function of the affected joints in all groups of the patients involved in the study. The correlation analysis has demonstrated the significant positive correlation between the decrease in the frequency of occurrence of the synovial cells with trisomy of chromosome 7 and the severity of the pain syndrome.

CONCLUSIONS

The results of the present study give evidence of the significant association between the genetic polymorphism of the glutathione-S-transferase gene and the frequency of cytogenetic abnormalities in the synovial cells of the knee joints of the patients suffering from CGA associated with LB. The treatment based on radon bath therapy caused a considerable decrease in the frequency of synovial cells with trisomy of chromosome 7 which correlated with the reduction of the intensity of the pain syndrome in these patients.

An Update on Oxidative Damage to Spermatozoa and Oocytes

On the one hand, reactive oxygen species (ROS) are mandatory mediators for essential cellular functions including the function of germ cells (oocytes and spermatozoa) and thereby the fertilization process. However, the exposure of these cells to excessive levels of oxidative stress by too high levels of ROS or too low levels of antioxidative protection will render these cells dysfunctional thereby failing the fertilization process and causing couples to be infertile. Numerous causes are responsible for the delicate bodily redox system being out of balance and causing disease and infertility. Many of these causes are modifiable such as lifestyle factors like obesity, poor nutrition, heat stress, smoking, or alcohol abuse. Possible correctable measures include foremost lifestyle changes, but also supplementation with antioxidants to scavenge excessive ROS. However, this should only be done after careful examination of the patient and establishment of the individual bodily antioxidant needs. In addition, other corrective measures include sperm separation for assisted reproductive techniques. However, these techniques have to be carried out very carefully as they, if applied wrongly, bear risks of generating ROS damaging the germ cells and preventing fertilization.

Osteoarthritis and telomere shortening

Osteoarthritis is the most common disease of joints caused by degradation of articular cartilage and subchondral bone. It is classified as primary form with unknown cause and as secondary form with known etiology. Genetic and epigenetic factors interact with environmental factors and contribute to the development of primary osteoarthritis. Thus far, many polymorphisms associated with osteoarthritis have been identified and recent studies also indicate the involvement of epigenetic factors (e.g., telomere shortening) in the initiation of this disorder. Accelerated shortening of telomeres was detected in osteoarthritis and other age-related diseases. Studies revealed that telomere length is severely reduced in blood leukocytes and chondrocytes of patients with osteoarthritis, and this may contribute to the initiation and development of osteoarthritis, whose major cause is still unknown.

Individual telomere length decay in patients with spondyloarthritis

Telomere length was sequentially determined in peripheral blood leukocytes (PBL) from patients with ankylosing spondylitis (AS; n = 44) and psoriatic arthritis (PsA; n = 42) followed through 2.93 ± 0.99 years, using a quantitative PCR (qPCR) assay. The initial telomere size from PsA patients was higher than those with cutaneous psoriasis only (n = 53), possibly due to the inflammatory condition. The qPCR assay was sensitive enough to evidence a significant telomere length shortening in PBL from practically all subjects and PsA patients showed a higher rate of loss of telomere sequence than patients with AS during the follow-up time.

The relationship between ultra-short telomeres, aging of articular cartilage and the development of human hip osteoarthritis

INTRODUCTION

Ultra-short telomeres caused by stress-induced telomere shortening are suggested to induce chondrocyte senescence in human osteoarthritic knees. Here we have further investigated the role of ultra-short telomeres in the development of osteoarthritis (OA) and in aging of articular cartilage in human hips.

MATERIALS AND METHODS

Cartilage was obtained from four different distances of the central weight-bearing area in human femoral heads (14 OA and 9 non-OA). Samples were split into three: one for quantification of ultra-short single telomeres by Universal STELA and mean telomere length measurement by Q-PCR; one for histological grading of OA, and one for immunohistochemical staining.

RESULTS

Load of ultra-short telomeres increased closer to the central weight-bearing area and correlated with cartilage degradation in both OA and non-OA samples. Mean telomere length decreased with decreasing distance to the central weight-bearing area, however, unexpectedly increased in the most central zone. This increase was associated with immunohistochemical findings of cells expressing markers characteristic of progenitor-like cells.

CONCLUSION

These findings suggest a role of short telomeres in the development of OA and in aging of articular cartilage. Furthermore, progenitor-like cells with long telomeres may be recruited to the most damaged areas of the cartilage.

The role of telomeres in musculoskeletal diseases

The telomeric region of repetitive DNA sequences at the end of chromosomes prevents end-to-end fusion of chromosome terminals and deterioration of the doublestrand free ends. Because of the 'end-replication problem', telomeres shorten with each round of cell division, resulting in cell senescence. The enzyme telomerase compensates for telomere shortening by elongating telomeric sequences, thereby prolonging the lifespan of the cell. Studies of articular cartilage and bone tissues have indicated that telomere shortening limits normal cell function and proliferation, while the telomere maintenance mechanisms of osteosarcoma cells facilitate escape from cell death and promote immortality. This article reviews the literature on this topic and provides an extensive discussion of the basic molecular biology and roles of telomeres and telomerase in musculoskeletal diseases such as osteoarthritis, osteoporosis and osteosarcoma. Findings to date suggest that telomeres and telomerase may become novel therapeutic targets for the diagnosis, treatment and prevention of musculoskeletal disorders.

Karyotyping of human chondrocytes in scaffold-assisted cartilage tissue engineering

Scaffold-assisted autologous chondrocyte implantation (ACI) is an effective clinical procedure for cartilage repair. The aim of our study was to evaluate the chromosomal stability of human chondrocytes subjected to typical cell culture procedures needed for regenerative approaches in polymer-scaffold-assisted cartilage repair. Chondrocytes derived from post mortem donors and from donors scheduled for ACI were expanded, cryopreserved and re-arranged in polyglycolic acid (PGA)-fibrin scaffolds for tissue culture. Chondrocyte redifferentiation was analyzed by electron microscopy, histology and gene expression analysis. Karyotyping was performed using GTG banding and fluorescence in situ hybridization on a single cell basis. Chondrocytes showed de- and redifferentiation accompanied by the formation of extracellular matrix and induction of typical chondrocyte marker genes like type II collagen in PGA-fibrin scaffolds. Post mortem chondrocytes showed up to 1.7% structural and high numbers of numerical (up to 26.7%) chromosomal aberrations, while chondrocytes from living donors scheduled for ACI showed up to 1.8% structural and up to 1.3% numerical alterations. Cytogenetically, cell culture procedures and PGA-fibrin scaffolds did not significantly alter chromosomal integrity of the chondrocyte genome. Human chondrocytes derived from living donors subjected to regenerative medicine cell culture procedures like cell expansion, cryopreservation and culture in resorbable polymer-based scaffolds show normal chromosomal integrity and normal karyotypes.

mtDNA haplogroup J modulates telomere length and nitric oxide production

Background

Oxidative stress due to the overproduction of nitric oxide (NO) and other oxygen reactive species (ROS), play a main role in the initiation and progression of the OA disease and leads to the degeneration of mitochondria. Therefore, the goal of this work is to describe the difference in telomere length of peripheral blood leukocytes (PBLs) and Nitric Oxide (NO) production between mitochondrial DNA (mtDNA) haplogroup J and non-J carriers, as indirect approaches of oxidative stress.

Methods

The telomere length of PBL was analyzed in DNA samples from 166 healthy controls (114 J and 52 non-J) and 79 OA patients (41 J and 38 non-J) by means of a validated qPCR method. The NO production was assessed in 7 carriers of the haplogroup J and 27 non-J carriers, by means of the colorimetric reaction of the Griess reagent in supernatants of cultured chondrocytes. Inducible nitric oxide synthase (iNOS) mRNA from these samples was analyzed by qPCR. Appropiated statistical analyses were performed

Results

Carriers of the haplogroup J showed a significantly longer telomere length of PBLs than non-J carriers, regardless of age, gender and diagnosis (p = 0.025). Cultured chondrocytes carrying the mtDNA haplogroup J also showed a lower NO production than non-J carriers (p = 0.043). No significant correlations between age and telomore length of PBLs were detected neither for carriers of the haplogroup J nor for non-J carriers. A strong positive correlation between NO production and iNOS expression was also observed (correlation coefficient = 0.791, p < 0.001).

Conclusion

The protective effect of the mtDNA haplogroup J in the OA disease arise from a lower oxidative stress in carriers of this haplogroup, since this haplogroup is related to lower NO production and hence longer telomere length of PBLs too.

Chromosomal aberrations involving telomeres and interstitial telomeric sequences

Telomeres are specialised nucleoproteic complexes localised at the physical ends of linear eukaryotic chromosomes that maintain their stability and integrity. In vertebrate chromosomes, the DNA component of telomeres is constituted by (TTAGGG)n repeats, which can be localised at the terminal regions of chromosomes (true telomeres) or at intrachromosomal sites (interstitial telomeric sequences or ITSs, located at the centromeric region or between the centromere and the telomere). In the past two decades, the use of molecular cytogenetic techniques has led to a new spectrum of spontaneous and clastogen-induced chromosomal aberrations being identified, involving telomeres and ITSs. Some aberrations involve the chromosome ends and, indirectly, the telomeric repeats located at the terminal regions of chromosomes (true telomeres). A second type of aberrations directly involves the telomeric sequences located at the chromosome ends. Finally, there is a third class of aberrations that specifically involves the ITSs. The aims of this review are to provide a detailed description of these aberrations and to summarise the available data regarding their induction by physical and chemical mutagens.