Lectin and other histochemical studies of the articular cartilage and the chondro-osseous junction of the normal human knee joint

Abstract

There are few studies on normal, adult diarthrodial joints which look in detail at the histochemical properties of the chondro-osseous junctional region. This study of the normal human knee joint was performed using lectin and other histochemical techniques. There were differences in the reactions of mineralised cartilage compared to those of hyaline cartilage with the former demonstrating more collagen and less glycosaminoglycans. Lectin histochemistry revealed more accessible terminal 2-deoxy,2-acetamido-alpha-D: -galactose and more N-acetyllactosamine but less fucosyl and alpha-2,6-linked-sialyl termini in the mineralised cartilage. The hyaline cartilage chondrocytes stained for N-glycans but those of mineralised cartilage did not. The staining patterns of prolongations and islands of uncalcified cartilage running through the calcified layer to abut bone and marrow spaces were distinct, resembling the patterns of the hyaline cartilage but with some unique features. A possible relationship was revealed between the presence of the Maclura pomifera ligand (Galbeta1,3GalNAcalpha1-) and mineralisation. Subchondral bone had a markedly restricted glycoprofile.

Phenotype-related differential α-2,6- or α-2,3-sialylation of glycoprotein N-glycans in human chondrocytes

“…Importantly, differences in N-glycan sialylation among the chondrocyte cell models were in correlation with differences in SiaT expression levels, indicating a crucial role of ST6Gal1 transcription for the phenotype-specific sialylation of chondrocyte glycoproteins. Our finding on the preponderant α-2,6-sialylation of human chondrocytes is in agreement with a previous lectin histochemical study of human knee joints reporting that chondrocytes in zones I – IV of normal hyaline cartilage were stained to a higher degree with SNA lectin than with Maackia amurensis agglutinin [37]. Interestingly, this feature distinguishes articular chondrocytes from their progenitor cells, the mesenchymal stem cells (MSC), which were previously shown to carry sialic acids predominantly in α-2,3-linkage [41], corresponding to the phenotype of the proliferating chondrocyte cell lines studied here .…”

“…This gap in our knowledge may result, at least in part, from the methodological challenges due to low SiaT transcription levels and linkage-type specific glycoprotein N-glycan analysis in human chondrocytes. Up to the present, evidence for the sialylation of chondrocytes has been generated using lectin histochemistry [37], lectin binding studies [22], enzyme-linked lectin assays [12,38], and enzyme activity assays [12]. In this study, we have employed an advanced approach to characterize the chondrocyte glycophenotype.…”

Application of WGA lectin staining for visualization of the connective tissue in skeletal muscle, bone, and ligament/tendon studies

“…Lectins were used previously in bone/tendon/ ligament research (Lyons et al,2007; Maffulli et al,2002; Schünke et al,1985) although their use as costaining markers for connective tissue visualization in immunohistochemical studies was very limited.…”

Aspects of the glycome of endochondral ossification

“…Despite its evident importance very little is known about the glycome of bone tissue. Somewhat more is known about human articular cartilage and its related sub-chondral bone plate (3,4). In embryonic development the skeleton is initially modelled in cartilage to be replaced by bone, except at the epiphyseal plates, by which postnatal growth to maturity is achieved.…”