AG-011

The aim of this study was to investigate the effect of IL‐10 on the phenotype polarization of macrophages and osteogenesis in diabetes mellitus type 2 (T2DM) rat jaw defects.

Lipopolysaccharide (LPS) and interleukin‐10 (IL‐10) were chosen to induce the polarization of macrophages. In vitro assessment included wound‐healing assay, western blotting, and alizarin red staining after co‐culture of the bone marrow‐derived mesenchymal stem cells (BMSCs) and induced macrophages. For in vivo study, IL‐10 was loaded on GelMA‐Heparin and applied to bone defects of the alveolar ridge in diabetic rats, while Bio‐Oss Collagen, simple GelMA‐Heparin, and blank control groups were set for contrast experiment. The mandibles of rats were processed for micro‐computed tomography, histology, and immunohistochemistry 1 week and 4 weeks after the operation.

IL‐10 induced expression of arginase 1, TGF‐β1, EGR2, and Mannose Receptor (CD206), whereas LPS induced expression of iNOS, TNF‐α, IL‐6, CD80. The BMSCs co‐cultured with macrophages induced by IL‐10 showed increased migration, osteogenic differentiation, and mineralization in vitro. Notably, the IL‐10‐laden GelMA‐Heparin group showed quicker new bone formation and a higher M2/M1 ratio of macrophages in the jawbone defect area compared with the control groups.

IL‐10 can stably induce macrophages to M2 type, thereby influencing BMSCs and improving the osteogenesis of jaw bone defects.

Few methods can cocurrently mimic the pathological characteristics and nature history of human abdominal aortic aneurysms (AAAs), especially for the exist of the self-healing tendency of rodents. This study tested a novel method for the AAA rat model induced by retroperitoneal implantation of an osmotic pump system with lipopolysaccharide (LPS) based on the hypothesis that chronic inflammation of perivascular adipose tissue directly influenced the development and progression of AAAs.

20 male Sprague-Dawley rats (10-month-old) fed with the Paigen diet were randomly divided into 4 groups: the blank group ×2, the sham group ×4, the empty capsule group ×4, and the LPS capsule group ×10. The LPS capsule group received implantations of the ALZET® osmotic pump capsule with LPS (3.6 μg/day) parallel to the abdominal aorta through a retroperitoneal approach. Two weeks later, 6 rats were randomly selected from the LPS capsule group to form the anti-inflammatory group and received implantations of another osmotic pump capsule with interleukin (IL)-10 (75 ng/day) through the same approach. The changes in abdominal aortic diameter were observed by ultrasound every 2 weeks, and samples were harvested for histopathologic and immunohistochemical analysis 6 weeks later.

Within the 6 weeks after modeling, the LPS capsule group showed sustained and significant aortic dilatation (P < 0.01), while the anti-inflammatory group showed a rapid and obvious shrinkage 2 weeks after the IL-10 osmotic pump capsule implantation (P < 0.01). The LPS capsule group presented excellent pathological mimicking of human AAAs and showed severe medial degeneration with the least elastic content among the 5 groups at the end of the sixth week (P < 0.05). Notably, the anti-inflammatory group showed perfect medial preservation with the most elastic content (P < 0.05) and the highest elastin/collagen ratio (P < 0.01) at the end of the study. Matrix metalloproteinases (MMP) 2 and 9 and toll-like receptor 2 showed strong expression in the LPS capsule group at the end of the sixth week, which was significantly higher than that in the blank group and sham group. Interestingly, the anti-inflammatory group showed a slightly higher MMP9 expression than the LPS capsule group though there was no statistical difference between them.

This novel method for the rat AAA model induced by retroperitoneal implantation of an osmotic pump capsule with LPS can concurrently mimic the histological characteristics and natural history of human AAAs. Further studies were needed to improve the osmotic pump system.