The biological effects of sex hormones on rabbit articular chondrocytes from different genders

Sex-dependent variation in cartilage adaptation: from degeneration to regeneration

Despite acknowledgement in the scientific community of sex-based differences in cartilage biology, the implications for study design remain unclear, with many studies continuing to arbitrarily assign demographics. Clinically, it has been well-established that males and females differ in cartilage degeneration, and accumulating evidence points to the importance of sex differences in the field of cartilage repair. However, a comprehensive review of the mechanisms behind this trend and the influence of sex on cartilage regeneration has not yet been presented. This paper aims to summarize current findings regarding sex-dependent variation in knee anatomy, sex hormones' effect on cartilage, and cartilaginous degeneration and regeneration, with a focus on stem cell therapies. Findings suggest that the stem cells themselves, as well as their surrounding microenvironment, contribute to sex-based differences. Accordingly, this paper underscores the contribution of both stem cell donor and recipient sex to sex-related differences in treatment efficacy. Cartilage regeneration is a field that needs more research to optimize strategies for better clinical results; taking sex into account could be a big factor in developing more effective and personalized treatments. The compilation of this information emphasizes the importance of investing further research in sex differences in cartilage biology.

Effects of Androgen Receptor Overexpression on Chondrogenic Ability of Rabbit Articular Chondrocytes

BACKGROUND

The role of sex hormones and their receptors has drawn much attention in the process of cartilage regeneration. This study aimed to investigate the effect of androgen receptor (AR) on the chondrogenic ability of articular chondrocytes and the related mechanism.

METHODS

Articular chondrocytes were isolated, cultured, identified by toluidine blue staining and then transduced with lentivirus carrying the AR gene. The cell viability was determined using Cell Counting Kit-8, and cell apoptosis was assessed by flow cytometry analysis. The effects of AR overexpression on the expression of cartilage-specific proteins and some signalling molecules were evaluated by real-time PCR and Western blotting. Using 24 New Zealand rabbits, the regeneration of rabbit articular cartilage defects was further investigated in vivo and evaluated histologically.

RESULTS

The overexpression of AR significantly reduced the apoptosis rate of chondrocytes but did not affect their proliferation. The overexpression of AR also promoted the expression of Sry-related HMG box 9, collagen II and aggrecan, decreased the expression of matrix metalloproteinase-13, and downregulated p-S6 and RICTOR. The experimental group with AR-overexpressing chondrocytes exhibited superior regeneration of cartilage defects.

CONCLUSION

AR overexpression can maintain the phenotype of chondrocytes and promote chondrogenesis in vitro and in vivo. mTOR-related signalling was inhibited.

Collagenated Porcine Heterologous Bone Grafts: Histomorphometric Evaluation of Bone Formation Using Different Physical Forms in a Rabbit Cancellous Bone Model

Collagenated porcine-derived bone graft materials exhibit osteoconductive properties and the development of different formulations intends to enhance bone regeneration. This study aims to evaluate bone healing in a rabbit cancellous bone defect in response to grafting with different physicochemical forms of heterologous porcine bone. Twenty-six adult male New Zealand White rabbits received two critical size femoral bone defects per animal (n = 52), each randomly assigned to one of the five tested materials (Apatos, Gen-Os, mp3, Putty, and Gel 40). Animals were sacrificed at 15- and 30-days post-surgery. Qualitative and quantitative (new bone, particle and connective tissue percentages) histological analyses were performed. Histomorphometry showed statistically significant differences in all evaluated parameters between mp3 and both Putty and Gel 40 groups, regardless of the timepoint (p < 0.05). Moreover, statistical differences were observed between Apatos and both Putty (p = 0.014) and Gel 40 (p = 0.007) groups, at 30 days, in regard to particle percentage. Within each group, regarding new bone formation, mp3 showed significant differences (p = 0.028) between 15 (40.93 ± 3.49%) and 30 (52.49 ± 11.04%) days. Additionally, intragroup analysis concerning the percentage of particles revealed a significant reduction in particle occupied area from 15 to 30 days in mp3 and Gen-Os groups (p = 0.009). All mp3, Gen-Os and Apatos exhibited promising results in terms of new bone formation, thus presenting suitable alternatives to be used in bone regeneration.

Efficacy of Particulated Juvenile Cartilage Allograft Transplantation for Osteochondral Lesions of the Talus

BACKGROUND

Particulated juvenile cartilage allograft transplantation (PJCAT) is a novel treatment option for osteochondral lesions of the talus (OLTs). It is typically employed as a salvage procedure after initial debridement and microfracture has failed as it is theorized to deliver viable hyaline cartilage. We hypothesized that PJCAT would be a safe and effective treatment option for OLTs.

METHODS

This is a retrospective case-control study of patients who underwent PJCAT for the treatment of OLTs at a single academic institution. Failure of the procedure was defined as no change or worsening of symptoms and/or the need for a subsequent cartilage restoration procedure. Variables recorded included preoperative magnetic resonance imaging (MRI) area and volume, intraoperative size, etiology, lesion location, sex, age, body mass index (BMI), history of prior surgery, American Orthopaedic Foot & Ankle Society score, and foot and ankle outcome score. Fifteen patients completed a minimum of 12 months of follow-up (mean, 34.6 months).

RESULTS

The failure rate of PJCAT in this series was 40% (6/15). Preoperative MRI area and intraoperative OLT size along with male sex were predictive of failure ( P < .05). Age, BMI, etiology, technique (open vs arthroscopic), history of prior surgery, and location of lesion were not predictors of failure in this limited series ( P > .05). Patients with lesions greater than 125 mm² area had a significant increased risk of clinical failure ( P < .05). Functional outcome scores were significantly better at final follow-up in the patients who had undergone successful treatment vs those who did not.

CONCLUSION

These findings demonstrate the association of preoperative MRI lesion area, intraoperative lesion size, and male sex as risk factors for failure of PJCAT setting of an already difficult to treat pathology.

LEVEL OF EVIDENCE

Level IV, retrospective case series.