Although atelocollagen gel is used as a scaffold for culturing human articular cartilage-derived chondrocytes, little is known about cell–gel interactions. In this study, we investigated the mechanism via which atelocollagen gel affects human articular cartilage-derived chondrocytes. Two types of three-dimensional cultures of human articular cartilage-derived chondrocytes (i.e., with and without atelocollagen gel) were compared. While the amount of atelocollagen gel in culture gradually decreased with time, it promoted the expression of matrix metalloproteinases (MMPs) during the early stages of culture. Genome-wide differential gene expression analysis revealed that cell membrane- and extracellular matrix-related genes were highly ranked among up- and down-regulated groups in cells cultured in the presence of atelocollagen gel. Among the integrin family of genes, the expression of integrin subunit alpha 2 and integrin subunit alpha 10 was significantly increased in the presence of atelocollagen gel. Blocking α2β1 integrin with the specific inhibitor BTT 3033 had a significant effect on cell proliferation, MMP expression, and cell shape, as well as on the response to mechanical stimulation. Taken together, our findings indicate that the α2β1 integrin pathway plays an important role in the interaction of atelocollagen gel with human articular cartilage-derived chondrocytes and may be a potential therapeutic target for articular cartilage disorders.

Early diagnosis of articular cartilage damage and repeated evaluation of treatment efficacy are essential for osteoarthritis treatment. In this study, we established a simple ultrasound grading system for early degenerative articular cartilage and investigated its relationship with cartilage biological characteristics. The ultrasound grading system were based on surface integrity (S1a: continuous high-echo lines, S1b: discontinuous or weak high-echo lines, S2: surface irregular) and cartilage echogenicity (E1: with > 50%, E2: < 50% hypoechoic area of total cartilage layer) and verified by surface roughness (Ra; μm) and histological staining. Ra was lower in S1 than in S2, and the percentage of hypoechoic and safranin O-stained areas was positively correlated. Then we examined its relationship with histopathological evaluation (OARSI grade), gene expression, and protein production in responded to pro-inflammatory cytokine (IL-1ß) stimulation. OARSI grades were different among S grades. The superficial layer of S1 had higher expression of Collagen10, aggrecan, Sox9, and lower expression of Collagen1 and BMP2 than that of S2. S1 responded more pronouncedly to IL-1ß in IL-6, IL-8, and CCL2 production than S2. There was no difference among the E-grades. Taken together, our findings indicate that ultrasound assessment using surface integrity can reflect the biological characteristics of early degenerative articular cartilage.

Case: An 8-year-old boy with left lateral ankle pain was diagnosed with acute osteomyelitis after methicillinsusceptible Staphylococcus aureus was identified in a subperiosteal abscess in the distal fibula that had been aspirated using an ultrasound-guided needle. Symptoms improved after 2 weeks of intravenous and 4 weeks of oral antimicrobial therapy; no additional treatment was required. No growth retardation or sequelae were observed at the 6-year follow-up. Conclusions:In acute osteomyelitis, the identification of subperiosteal abscess is key for early diagnosis. Ultrasound evaluation of the distal fibula should also be considered in the diagnosis of lateral ankle pain in children.Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSCC/B920).