Background

Distraction osteogenesis (DO) is a widely used bone regenerative technique. However, the DO process is slow, and the consolidation phase is long. Therefore, it is of great clinical significance to explore the mechanism of DO, and shorten its duration. Recent studies reported that stem cell exosomes may play an important role in promoting angiogenesis related to DO, but the mechanism remains unclear.

Methods

Canine endothelial colony-forming cells (ECFCs) were isolated and cultured, and the expression of THBS1 in canine ECFCs were inhibited using a lentiviral vector. The exosomes secreted by canine ECFCs were isolated and extracted, and the effect of exosomes on the angiogenic activity of Human umbilical vein endothelial cells (HUVECs) was detected by proliferation, migration, and tube formation experiments. WB and qRT-PCR were used to explore the effects and mechanisms of THBS1-mediated ECFC-Exos on HUVECs angiogenesis. Then, a mandibular distraction osteogenesis (MDO) model was established in adult male beagles, and exosomes were injected into the canine peripheral blood. Micro-CT, H&E, Masson, and IHC staining were used to explore the effects and mechanisms of THBS1-mediated ECFC-Exos on angiogenesis and osteogenesis in the DO area.

Results

ECFC-Exo accelerated HUVECs proliferation, migration and tube formation, and this ability was enhanced by inhibiting the expression of THBS1 in ECFC-Exo. Using Western blot-mediated detection, we demonstrated that inhibiting THBS1 expression in ECFCs-Exo activated PI3K, AKT, and ERK phosphorylation levels in HUVECs, which promoted VEGF and bFGF expressions. In the DO model of the canine mandible, ECFCs-Exo injected into the peripheral blood aggregated into the DO gap, thus promoting angiogenesis and bone formation in the DO tissue by reducing THBS1 expression in ECFC-Exo.

Conclusion

Our findings suggested that ECFC-Exos markedly enhances angiogenesis of endothelial cells, and promotes bone healing in canine MDO. Thus, THBS1 plays a crucial role in the ECFC-Exos-mediated regulation of canine MDO angiogenesis and bone remodeling.

The translational potential of this article

This study reveals that the angiogenic promotion via THBS1 suppression in ECFC-Exos may be a promising strategy for shortening the DO duration.

中文翻译：

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ECFC 衍生的外泌体 THBS1 通过 PI3K/AKT/ERK 通路介导牵张成骨中的血管生成和成骨

背景

牵引成骨（DO）是一种广泛使用的骨再生技术。但是，DO 过程很慢，巩固阶段很长。因此，探索DO的发生机制，缩短其病程，具有重要的临床意义。最近的研究报道，干细胞外泌体可能在促进与 DO 相关的血管生成中发挥重要作用，但其机制仍不清楚。

方法

分离和培养犬内皮集落形成细胞 (ECFC)，并使用慢病毒载体抑制犬 ECFC 中 THBS1 的表达。分离提取犬ECFCs分泌的外泌体，通过增殖、迁移和成管实验检测外泌体对人脐静脉内皮细胞（HUVECs）血管生成活性的影响。WB和qRT-PCR用于探索THBS1介导的ECFC-Exos对HUVECs血管生成的影响和机制。然后，在成年雄性比格犬中建立下颌牵引成骨（MDO）模型，并将外泌体注射到犬外周血中。Micro-CT、H&E、Masson 和 IHC 染色用于探索 THBS1 介导的 ECFC-Exos 对 DO 区血管生成和成骨的影响和机制。

结果

ECFC-Exo 加速了 HUVECs 的增殖、迁移和管形成，并且通过抑制 ECFC-Exo 中 THBS1 的表达来增强这种能力。使用蛋白质印迹介导的检测，我们证明抑制 ECFCs-Exo 中的 THBS1 表达可激活 HUVEC 中的 PI3K、AKT 和 ERK 磷酸化水平，从而促进 VEGF 和 bFGF 的表达。在犬下颌骨的 DO 模型中，注入外周血的 ECFCs-Exo 聚集到 DO 间隙中，从而通过降低 ECFC-Exo 中 THBS1 的表达来促进 DO 组织中的血管生成和骨形成。

结论

我们的研究结果表明，ECFC-Exos 显着增强了内皮细胞的血管生成，并促进了犬 MDO 的骨愈合。因此，THBS1 在 ECFC-Exos 介导的犬 MDO 血管生成和骨重塑调节中起着至关重要的作用。

本文的翻译潜力

该研究表明，通过 ECFC-Exos 中的 THBS1 抑制促进血管生成可能是缩短 DO 持续时间的有前景的策略。