Aims: This study aimed to define the histopathology of degenerated humeral head cartilage and synovial inflammation of the glenohumeral joint in patients with omarthrosis (OmA) and cuff tear arthropathy (CTA). Additionally, the potential of immunohistochemical tissue biomarkers in reflecting the degeneration status of humeral head cartilage was evaluated.Methods: Specimens of the humeral head and synovial tissue from 12 patients with OmA, seven patients with CTA, and four body donors were processed histologically for examination using different histopathological scores. Osteochondral sections were immunohistochemically stained for collagen type I, collagen type II, collagen neoepitope C1,2C, collagen type X, and osteocalcin, prior to semiquantitative analysis. Matrix metalloproteinase (MMP)-1, MMP-3, and MMP-13 levels were analyzed in synovial fluid using enzyme-linked immunosorbent assay (ELISA).Results: Cartilage degeneration of the humeral head was associated with the histological presentation of: 1) pannus overgrowing the cartilage surface; 2) pores in the subchondral bone plate; and 3) chondrocyte clusters in OmA patients. In contrast, hyperplasia of the synovial lining layer was revealed as a significant indicator of inflammatory processes predominantly in CTA. The abundancy of collagen I, collagen II, and the C1,2C neoepitope correlated significantly with the histopathological degeneration of humeral head cartilage. No evidence for differences in MMP levels between OmA and CTA patients was found.Conclusion: This study provides a comprehensive histological characterization of humeral cartilage and synovial tissue within the glenohumeral joint, both in normal and diseased states. It highlights synovitis and pannus formation as histopathological hallmarks of OmA and CTA, indicating their roles as drivers of joint inflammation and cartilage degradation, and as targets for therapeutic strategies such as rotator cuff reconstruction and synovectomy.Cite this article: Bone Joint Res 2024;13(10):596–610.

Galectin-4 (Gal-4) is a member of the galectin family, which have been identified as galactose-binding proteins. Gal-4 possesses two tandem repeat carbohydrate recognition domains and acts as a cross-linking bridge in sulfatide-dependent glycoprotein routing. We herein document its upregulation in osteoarthritis (OA) in correlation with the extent of cartilage degradation in vivo. Primary human OA chondrocytes in vitro respond to carbohydrate-inhibitable Gal-4 binding with the upregulation of pro-degradative/-inflammatory proteins such as interleukin-1β (IL-1β) and matrix metalloproteinase-13 (MMP-13), as documented by RT-qPCR-based mRNA profiling and transcriptome data processing. Activation of p65 by phosphorylation of Ser536 within the NF-κB pathway and the effect of three p65 inhibitors on Gal-4 activity support downstream involvement of such signaling. In 3D (pellet) cultures, Gal-4 presence causes morphological and biochemical signs of degradation. Taken together, our findings strongly support the concept of galectins acting as a network in OA pathogenesis and suggest that blocking their activity in disease progression may become clinically relevant in the future.

Implant removal is a common method to quantify the level of osseointegration in small animal studies. Due to small implant sizes, precise alignment in removal experiments is crucial to obtain accurate and reproducible results. This study proposes a novel approach using photon counting detector computed tomography (PCD-CT) data and additive manufacturing to improve implant alignment. A simplified finite element model was designed to investigate the effect of implant misalignment in removal tests. Additionally, the geometry of 43 rat tibiae was assessed utilizing PCD-CT scans, and subsequently specimen-specific positioning fixtures were designed and manufactured using computer-aided design and tabletop 3D printers. The accuracy and precision of the specimen alignment within the fixtures were assessed both visually (current state of the art) and through projectional radiography in both cranial-caudal (CC) and anterior-posterior (AP) projections to quantify true misalignment. Finite element analysis demonstrated that stresses and displacements are sensitive to misalignment, potentially leading to substantial inaccuracies in the implant removal measurements. Statistical analysis of visual assessments revealed poor to moderate inter- and intra-operator variability (0.336 ≤ ICC ≤ 0.625) and low correlation with true misalignment (0.024 ≤ R² ≤ 0.204). Specimen alignment within the fixtures (CC: 0.23 ± 0.46°, AP: 1.00 ± 0.82°) showed improvement in accuracy and precision compared to visual assessments (CC: 0.88 ± 0.92°, AP: 1.11 ± 1.15°). The proposed specimen fixation and alignment, which relies on clinical imaging data and inexpensive 3D printers, offers a cost- and time-effective alternative to visual assessments, which could considerably improve the accuracy and precision in osseointegration assessment.

Background/Objectives: Galectins contribute to the pathogenesis of osteoarthritis (OA) by amplifying inflammatory and catabolic signaling, yet targeted therapeutic approaches remain limited. Three Dimensional (3D) models offer a promising platform to study human OA pathophysiology and evaluate novel interventions. Methods: We established 3D pellet cultures derived from human OA chondrocytes to investigate galectin-induced extracellular matrix (ECM) remodeling and the chondroprotective potential of phytochemicals. OA pellets were stimulated with individual galectins (Gal-1, -3, -4, -8) or a Gal-1/-3/-8 mixture, followed by co-treatment with Brazilin, Diacerein, Quercetin, Resveratrol, or Avocado-Soybean Unsaponifiables (ASU). Morphological, histological, biochemical, and gene expression analyses were performed to assess tissue integrity and molecular responses. Results: Galectin treatment induced pronounced pellet shrinkage, matrix depletion, and upregulation of matrix-degrading enzymes (MMP-1, MMP-3, MMP-13, ADAMTS-4), while suppressing matrix synthesis markers (COL2A1, COL1A1), highlighting their cooperative catabolic effects. Co-treatment with phytochemicals conferred differential protection: Brazilin and Diacerein most consistently preserved pellet size, reduced matrix-degrading gene expression, and attenuated pro-MMP-13 secretion. Resveratrol restored histological matrix density but failed to suppress pro-MMP-13 secretion. Notably, no phytochemical fully restored COL2A1 expression under galectin-induced stress. Conclusions: Our study identifies Brazilin, Diacerein, and Resveratrol as promising modulators of galectin-driven cartilage degeneration and demonstrates the translational potential of patient-derived chondrogenic pellets as a human-relevant platform for preclinical drug evaluation in OA. The 3D culture effectively recapitulates key aspects of OA pathophysiology and offers a robust system to advance therapeutic discovery targeting ECM remodeling.

Background: Intervertebral disc (IVD) degeneration is associated with severe clinical symptoms including chronic back pain. Galectins are a family of carbohydrate‐binding proteins, some of which can induce functional disease markers in IVD cells and other musculoskeletal tissues. Galectin‐4 and ‐8 were shown to trigger disease‐promoting activity in chondrocytes, but their effects on IVD cells have not been investigated yet. Methods: IVD specimens from 36 patients with spondylosis, spondylolisthesis, and scoliosis were assessed immunohistochemically for the presence of galectin‐4 and ‐8. The degrees of radiological (Pfirrmann grade) and histopathological (Rutges score) degeneration of all specimens were correlated with histological galectin scores. To assess galectin functions, separate cell cultures of annulus fibrosus (AF) and nucleus pulposus (NP) ( n = 21) were established. Cell cultures were treated with recombinant galectin‐4, ‐8 (24 μg/mL), or Interleukin‐1β (IL‐1β) (10 ng/mL) and analyzed using RT‐qPCR and In‐Cell Western (ICW). Potential binding sites for galectins including sialylated N‐glycans and LacdiNAc structures were determined in AF and NP cells using liquid chromatography‐electrospray ionization‐tandem mass spectrometry (LC‐ESI‐MS/MS). Results: The immunohistochemical presence of galectin‐4 in IVD specimens correlated with histopathological and clinical degeneration scores of patients, whereas galectin‐8 did not show significant correlations. Both galectins were detected across IVD compartments except for the endplate. In vitro, both galectins activated the nuclear factor‐kB pathway and induced functional disease markers (Interleukin‐8 (CXCL8) and matrix metalloproteinase‐3 (MMP3) mRNA). NP cells were more responsive to galectins and IL‐1β than AF cells, indicating region‐specific differences in galectin sensitivity. Conclusion: This study identifies galectin‐4 as a novel molecular player in the pathogenesis of IVD degeneration.