Department of Orthopedics, the First Affiliated Hospital of Anhui Medical University, 218 Jixi Road, Hefei, 230000, China.
Stem Cell Res Ther. 2021 Mar 29;12(1):215. doi: 10.1186/s13287-021-02278-w.
Dysfunction of mesenchymal stem cells (MSCs) is recognized as critical to the pathogenesis of glucocorticoid-induced osteoporosis (GIO), suggesting the potential of MSC-targeting interventions for this disorder. As the miR-133a has been shown to play an important role in bone metabolism, we hypothesized that miR-133a may also be involved in GIO.
In the in vitro study, we examined the effect of miR-133a antagomir on DEX-treated MSCs, including proliferation, apoptosis, osteoblast, and adipocyte differentiation, then, we explored the mechanism of these effects of miR-133a silencing through measuring the phosphorylation of ERK1/2 and its regulator FGFR1 via western blot and qRT-PCR. In the in vivo study, we developed a GIO rat model by injecting methylprednisolone and modulated the miR-133a expression in the femur by intramedullary injection of the miR-133a antagomir, and then micro-CT analyses and histological staining of the femurs were used to investigate the effect of miR-133a silencing on bone loss of the GIO rats.
qRT-PCR analysis indicated that glucocorticoid induced high miR-133a expression in MSCs and animal models. The in vitro study showed that miR-133a antagomir significantly promoted cell proliferation, viability, and osteoblast differentiation and inhibited adipocyte differentiation in DEX-treated MSCs. Furthermore, the expression of p-ERK1/2 and FGFR1 in DEX-treated MSCs was also upregulated by miR-133a antagomir. Then we investigated the effect of miR-133a silencing on the bone architecture of GIO models, micro-CT analysis showed that miR-133a antagomir attenuated the loss of bone mass and improved the trabecular and cortical parameters induced by methylprednisolone. Histological study showed that miR-133a silencing simultaneously increased bone formation and decreased marrow fat accumulation in GIO rats.
Our findings suggested that miR-133a is strongly associated with GIO and similar disorders induced by glucocorticoids in MSCs. Silencing miR-133a resulted in positive effects on GC-treated MSCs and on bone loss in GIO animal models. Moreover, the FGFR1-MAPK/ERK signaling may be involved in the protective effect of miR-133a silencing.
间充质干细胞（MSCs）功能障碍被认为是糖皮质激素诱导性骨质疏松症（GIO）发病机制的关键，这表明针对 MSC 的干预措施可能对这种疾病有效。由于 miR-133a 已被证明在骨代谢中发挥重要作用，我们假设 miR-133a 也可能参与 GIO。
在体外研究中，我们研究了 miR-133a 拮抗剂对 DEX 处理的 MSC 的影响，包括增殖、凋亡、成骨细胞和脂肪细胞分化，然后，我们通过 Western blot 和 qRT-PCR 测量 ERK1/2 磷酸化及其调节因子 FGFR1 来探索 miR-133a 沉默对这些作用的机制。在体内研究中，我们通过注射甲泼尼龙建立 GIO 大鼠模型，并通过髓内注射 miR-133a 拮抗剂调节股骨中的 miR-133a 表达，然后使用 micro-CT 分析和股骨组织学染色来研究 miR-133a 沉默对 GIO 大鼠骨丢失的影响。
qRT-PCR 分析表明糖皮质激素诱导 MSC 中 miR-133a 高表达和动物模型。体外研究表明，miR-133a 拮抗剂显著促进 DEX 处理的 MSC 细胞增殖、活力和成骨细胞分化，并抑制脂肪细胞分化。此外，DEX 处理的 MSC 中 p-ERK1/2 和 FGFR1 的表达也被 miR-133a 拮抗剂上调。然后，我们研究了 miR-133a 沉默对 GIO 模型骨结构的影响，micro-CT 分析表明，miR-133a 拮抗剂减轻了由甲泼尼龙诱导的骨量丢失，并改善了皮质和小梁参数。组织学研究表明，miR-133a 沉默同时增加了 GIO 大鼠的骨形成并减少了骨髓脂肪堆积。
我们的研究结果表明，miR-133a 与 GIO 以及糖皮质激素诱导的 MSC 中类似的疾病密切相关。沉默 miR-133a 对 GC 处理的 MSC 以及 GIO 动物模型的骨丢失有积极影响。此外，FGFR1-MAPK/ERK 信号通路可能参与了 miR-133a 沉默的保护作用。
