Human dental pulp stem cells (DPSCs) have emerged as an important source of stem cells in the tissue engineering, and hypoxia will change various innate characteristics of DPSCs and then affect dental tissue regeneration. Nevertheless, little is known about the complicated molecular mechanisms. In this study, we aimed to investigate the influence and mechanism of miR-140-3p on DPSCs under hypoxia condition. Hypoxia was induced in DPSCs by Cobalt chloride (CoCl₂) treatment. The osteo/dentinogenic differentiation capacity of DPSCs was assessed by alkaline phosphatase (ALP) activity, Alizarin Red S staining and main osteo/dentinogenic markers. A luciferase reporter gene assay was performed to verify the downstream target gene of miR-140-3p. This research exhibited that miR-140-3p promoted osteo/dentinogenic differentiation of DPSCs under normoxia environment. Furthermore, miR-140-3p rescued the CoCl₂-induced decreased osteo/odontogenic differentiation potentials in DPSCs. Besides, we investigated that miR-140-3p directly targeted lysine methyltransferase 5B (KMT5B). Surprisingly, we found inhibition of KMT5B obviously enhanced osteo/dentinogenic differentiation of DPSCs both under normoxia and hypoxia conditions. In conclusion, our study revealed the role and mechanism of miR-140-3p for regulating osteo/dentinogenic differentiation of DPSCs under hypoxia, and discovered that miR-140-3p and KMT5B might be important targets for DPSC-mediated tooth or bone tissue regeneration.

人牙髓干细胞（DPSCs）已成为组织工程干细胞的重要来源，缺氧会改变DPSCs的各种先天特性，进而影响牙组织再生。然而，人们对复杂的分子机制知之甚少。本研究旨在探讨miR-140-3p对缺氧条件下DPSCs的影响及其机制。氯化钴 (CoCl ₂） 治疗。通过碱性磷酸酶 (ALP) 活性、茜素红 S 染色和主要的骨/牙本质标记物评估 DPSC 的骨/牙本质分化能力。进行荧光素酶报告基因测定以验证 miR-140-3p 的下游靶基因。该研究表明，miR-140-3p 在常氧环境下促进 DPSCs 的骨/牙本质分化。此外，miR-140-3p 拯救了 CoCl ₂-诱导 DPSCs 中骨/牙源性分化潜能降低。此外，我们研究了 miR-140-3p 直接靶向赖氨酸甲基转移酶 5B (KMT5B)。令人惊讶的是，我们发现在常氧和缺氧条件下抑制 KMT5B 明显增强了 DPSC 的骨/牙本质分化。总之，我们的研究揭示了 miR-140-3p 在缺氧条件下调节 DPSCs 骨/牙本质分化的作用和机制，并发现 miR-140-3p 和 KMT5B 可能是 DPSC 介导的牙齿或骨组织再生的重要靶点.