Evaluation of age-related changes in the structure of the equine tarsometatarsal osteochondral unit

Caviunin glycoside (CAFG) from Dalbergia sissoo attenuates osteoarthritis by modulating chondrogenic and matrix regulating proteins

ETHNOPHARMACOLOGICAL RELEVANCE

Dalbergia sissoo DC. (Indian rosewood or Sheesham) is a traditional medicinal plant, reported since time immemorial for its analgesic, anti-nociceptive, anti-inflammatory, and immuno-modulatory properties. D. sissoo DC (DS). is being used traditionally to cure joint inflammation and joint pain.

AIM

To study the potential of DS leaves and its derived novel compound CAFG to treat the clinical symptoms of osteoarthritis (OA) and its underlying mechanism.

METHODS

The chemical profile of DS extract (DSE) with isoflavonoids and isoflvaonoid glycosides from the DS was established by UHPLC-PDA and UHPLC-MS/MS. Monosodium iodoacetate (MIA) was injected into the knee joint to develop the OA model in rats. DSE was given orally for 28 days daily at 250 and 500 mg.kg^-1day^-1. For in-vitro experiments, chondrocytes isolated from joint articular cartilage were negatively induced with interleukin-1β (IL-1β) and CAFG was given to the cells as a co-treatment.

RESULTS

Chondrocytes undergo apoptosis following inflammation and proteoglycan synthesis affected in MIA injected knees. DSE administration prevented these effects as assessed by H&E and Toluidine blue staining. Micro-CT analysis showed that subchondral bone loss was restored. DSE decreased elevated serum levels of cartilage-bone degradation (CTX-I, CTX-II, and COMP), inflammation markers IL-1β, and matrix-degrading MMP-3 and 13. The effects of IL-1β on gene expression of chondrocytes were reversed by CAFG treatment at 1 μM.

CONCLUSION

Data showed that DSE protected joint cartilage and deterioration in subchondral bone in vivo while in in-vitro, its active ingredient CAFG prevented interleukin-1β induced effects and inhibited OA. This finding suggest that DSE and CAFG could be used as a possible therapeutic to treat osteoarthritis.

Automated analysis of rabbit knee calcified cartilage morphology using micro-computed tomography and deep learning

Structural dynamics of calcified cartilage (CC) are poorly understood. Conventionally, CC structure is analyzed using histological sections. Micro‐computed tomography (µCT) allows for three‐dimensional (3D) imaging of mineralized tissues; however, the segmentation between bone and mineralized cartilage is challenging. Here, we present state‐of‐the‐art deep learning segmentation for µCT images to assess 3D CC morphology. The sample includes 16 knees from 12 New Zealand White rabbits dissected into osteochondral samples from six anatomical regions: lateral and medial femoral condyles, lateral and medial tibial plateaus, femoral groove, and patella (n = 96). The samples were imaged with µCT and processed for conventional histology. Manually segmented CC from the images was used to train segmentation models with different encoder–decoder architectures. The models with the greatest out‐of‐fold evaluation Dice score were selected. CC thickness was compared across 24 regions, co‐registered between the imaging modalities using Pearson correlation and Bland–Altman analyses. Finally, the anatomical CC thickness variation was assessed via a Linear Mixed Model analysis. The best segmentation models yielded average Dice of 0.891 and 0.807 for histology and µCT segmentation, respectively. The correlation between the co‐registered regions was strong (r = 0.897, bias = 21.9 µm, standard deviation = 21.5 µm). Finally, both methods could separate the CC thickness between the patella, femoral, and tibial regions (p < 0.001). As a conclusion, the proposed µCT analysis allows for ex vivo 3D assessment of CC morphology. We demonstrated the biomedical relevance of the method by quantifying CC thickness in different anatomical regions with a varying mean thickness. CC was thickest in the patella and thinnest in the tibial plateau. Our method is relatively straightforward to implement into standard µCT analysis pipelines, allowing the analysis of CC morphology. In future research, µCT imaging might be preferable to histology, especially when analyzing dynamic changes in cartilage mineralization. It could also provide further understanding of 3D morphological changes that may occur in mineralized cartilage, such as thickening of the subchondral plate in osteoarthritis and other joint diseases.

Age-Dependent Subchondral Bone Remodeling and Cartilage Repair in a Minipig Defect Model

After cartilage injury and repair, the subchondral bone plate remodels. Skeletal maturity likely impacts both bone remodeling and inherent cartilage repair capacity. The objective of this study was to evaluate subchondral bone remodeling as a function of injury type, repair scenario, and skeletal maturity in a Yucatan minipig model. Cartilage defects (4 mm) were created bilaterally in the trochlear groove. Treatment conditions included a full thickness chondral defect (full chondral defect, n = 3 adult/3 juvenile), a partial thickness (∼50%) chondral defect (PCD, n = 3/3), and FCD treated with microfracture (MFX, n = 3/3). At 6 weeks postoperatively, osteochondral samples containing the lesion site were imaged by micro-computed tomography (CT) and analyzed by histology and immunohistochemistry. Via micro-CT, FCD and MFX groups showed increased bone loss in juveniles compared with adults. Quantification of histology using the ICRS II scoring system showed equal overall assessment for the FCD groups and better overall assessment in juvenile animals treated with MFX compared with adults. All FCD and MFX groups were inferior to control samples. For the PCD injury, both age groups had values close to the control values. For the FCD groups, there were greater alterations in the subchondral bone in juveniles compared with adults. Staining for collagen II showed more intense signals in juvenile FCD and MFX groups compared with adults. This large animal study of cartilage repair shows the significant impact of skeletal maturity on the propensity of subchondral bone to remodel as a result of chondral injury. This will improve selection criteria for animal models for studying cartilage injury, repair, and treatment.

Análise termogravimétrica da cartilagem articular de ratos exercitados após imobilização

INTRODUÇÃO: A imobilização articular é uma técnica de tratamento frequentemente utilizada na ortopedia e, associada ao processo de senescência, promove alterações tanto na estrutura quanto na síntese e biomecânica do tecido cartilaginoso. OBJETIVO: Descrever os efeitos da imobilização, da remobilização livre e por meio de exercício físico sobre a cartilagem articular de ratos situados em duas faixas etárias. MÉTODOS: Trinta e nove ratos Wistar divididos em dois grupos etários, um grupo adulto (cinco meses de idade) e um idoso (15 meses de idade), subdivididos em: controle, imobilizado, remobilizado livre e remobilizado por meio de exercício físico. Os membros posteriores dos ratos foram imobilizados por sete dias. O protocolo de exercícios foi composto por cinco sessões diárias de natação, de 25 minutos cada. A cartilagem articular do quadril foi submetida à análise termogravimétrica, tendo sido avaliado seu conteúdo de água. RESULTADOS: Nos animais adultos a imobilização reduziu a quantidade de água presente no tecido cartilaginoso, e os protocolos de remobilização foram eficazes para restabelecer a condição inicial do tecido. Nos animais idosos não houve diferença significativa entre os grupos, porém o grupo idoso controle obteve resultado significantemente menor que o grupo adulto controle (X: 13,10 ± 5,24 vs 10,70 ± 1,95). CONCLUSÕES: A imobilização e o processo de senescência induzem a diminuição do conteúdo de água da cartilagem articular e os protocolos de remobilização foram eficientes para restabelecer esta propriedade apenas nos animais adultos.