Department of Orthopaedic Surgery, Shiga University of Medical Science, Setatsukinowa-cho, Otsu, 520-2192, Shiga, Japan.
Department of Stem Cell Biology and Regenerative Medicine, Shiga University of Medical Science, Otsu, 520-2192, Shiga, Japan.
BMC Musculoskelet Disord. 2023 Jul 18;24(1):585. doi: 10.1186/s12891-023-06710-5.
Diabetes mellitus (DM) causes bone dysfunction due to poor bone quality, leading to severe deterioration in patient of quality of life. The mechanisms of bone metabolism in DM remain unclear, although chemical and/or mechanical factors are known to disrupt the homeostasis of osteoblasts and osteoclasts. The purpose of this study was to identify the changes of osteoblasts and osteoclasts under long-term hyperglycaemic conditions, using a mouse fracture model of long-term hyperglycemia (LT-HG).
C57BL/6J mice and green fluorescent protein (GFP) -positive bone marrow transplanted C57BL/6J mice with LT-HG, maintained under a state of hyperglycaemia for 2 months, were used in this study. After the experimental fracture, we examined the immunohistochemical expression of proinsulin and tumor necrosis factor (TNF) -α at the fracture site. C57BL/6J fracture model mice without hyperglycaemia were used as controls.
In the LT-HG mice, chondrocyte resorption was delayed, and osteoblasts showed an irregular arrangement at the callus site. The osteoclasts were scattered with a decrement in the number of nuclei. The expression of proinsulin was confirmed in bone marrow derived cells (BMDCs) with neovascularization 2 and 3 weeks after fracture. Immunopositivity for TNF-α was also confirmed in immature chondrocytes and BMDCs with neovascularization at 2 weeks, and the number of positive cells was not decreased at 3 weeks. Examination of GFP-grafted hyperglycaemic mice showed that the majority of cells at the fracture site were GFP-positive. Immunohistochemistry showed that the rate of double positives was 15% for GFP and proinsulin and 47% for GFP and TNF-α.
LT-HG induces an increase in the number of proinsulin and TNF-α positive cells derived from BMDCs. We suggest that proinsulin and TNF-α positive cells are involved in both bone formation and bone resorption after fracture under hyperglycaemic conditions, resulting in the delay of bone healing.
糖尿病（DM）会导致骨功能障碍，原因是骨质量差，导致患者的生活质量严重恶化。尽管已知化学和/或机械因素会破坏成骨细胞和破骨细胞的内稳态，但 DM 中骨代谢的机制仍不清楚。本研究的目的是在长期高血糖（LT-HG）的小鼠骨折模型中，确定成骨细胞和破骨细胞的变化。
使用 C57BL/6J 小鼠和 GFP 阳性骨髓移植 C57BL/6J 小鼠的 LT-HG 模型，使其处于高血糖状态 2 个月。在实验性骨折后，我们检测了骨折部位胰岛素原和肿瘤坏死因子（TNF）-α的免疫组织化学表达。未发生高血糖的 C57BL/6J 骨折模型小鼠作为对照。
在 LT-HG 小鼠中，软骨细胞吸收延迟，成骨细胞在骨痂部位呈不规则排列。破骨细胞散在分布，核数减少。骨折后 2 周和 3 周，在新生血管化的骨髓来源细胞（BMDCs）中证实了胰岛素原的表达。2 周时，在新生血管化的未成熟软骨细胞和 BMDCs 中也证实了 TNF-α 的免疫阳性，3 周时阳性细胞数量没有减少。对移植高血糖 GFP 小鼠的检查表明，骨折部位的大多数细胞为 GFP 阳性。免疫组化显示 GFP 和胰岛素原的双阳性率为 15%，GFP 和 TNF-α 的双阳性率为 47%。
LT-HG 导致 BMDC 来源的胰岛素原和 TNF-α阳性细胞数量增加。我们认为，在高血糖条件下骨折后，胰岛素原和 TNF-α阳性细胞参与骨形成和骨吸收，导致骨愈合延迟。
