Department of Biochemistry and Molecular Genetics, Midwestern University, Downers Grove, Illinois, USA.
Dental Institute, Midwestern University Clinics, Downers Grove, Illinois, USA.
Cell Reprogram. 2023 Jun;25(3):109-120. doi: 10.1089/cell.2023.0004. Epub 2023 May 18.
Dental pulp stem cells (DPSCs) and stem cells from human exfoliated deciduous teeth (SHED) are a source of mesenchymal stem cells with the potential to differentiate into several cell types. We initially isolated SHED cells and compared their osteogenic capacity with commercially available DPSCs. Both cells exhibited similar capacities of growth and osteogenic differentiation. A fourfold to sixfold increase in endogenous microRNA26a (miR26a) expression during osteogenic differentiation of preosteoblasts and a similar but attenuated increase (twofold to fourfold) in differentiating SHED was observed, suggesting a role in the process. We, therefore, overexpressed miR26a in SHED to determine if the osteogenic differentiation capacity can be potentiated . SHED with a threefold increase in miR26a expression showed increased growth rate when compared with parent cells. When exposed to an osteogenic differentiating promoting medium, the miR26a overexpressing cells showed 100-fold increases in the expression of bone marker genes such as type 1 collagen, alkaline phosphatase, and Runx2. The mineralization capacity of these cells was also increased 15-fold. As miR26a targets regulate several bone-specific genes, we evaluated the effect of miR26a overexpression on established targets. We found a moderate decrease in SMAD1 and a profound decrease in PTEN expression. miR26a could potentiate its effect on osteoblast differentiation by its ability to inhibit PTEN and increase the viability of cells and their numbers, a process essential in osteoblast differentiation. Our studies suggest that the upregulation of miR26a can increase bone formation and may serve as an important target to further investigate its potential in tissue engineering applications.
牙髓干细胞（DPSCs）和人乳牙脱落干细胞（SHED）是间充质干细胞的来源，具有分化为多种细胞类型的潜力。我们最初分离了 SHED 细胞，并比较了它们的成骨能力与市售的 DPSCs。这两种细胞的生长和成骨分化能力相似。在成骨前体细胞的成骨分化过程中，内源性 microRNA26a（miR26a）表达增加了 4 到 6 倍，而在分化的 SHED 中则观察到类似但减弱的增加（2 到 4 倍），表明其在该过程中起作用。因此，我们在 SHED 中过表达 miR26a，以确定其成骨分化能力是否可以增强。与亲本细胞相比，miR26a 表达增加了 3 倍的 SHED 显示出生长速度加快。当暴露于促进成骨分化的培养基中时，过表达 miR26a 的细胞中骨标志物基因（如 I 型胶原、碱性磷酸酶和 Runx2）的表达增加了 100 倍。这些细胞的矿化能力也增加了 15 倍。由于 miR26a 的靶基因调节几个骨特异性基因，我们评估了过表达 miR26a 对已建立靶基因的影响。我们发现 SMAD1 的表达适度降低，PTEN 的表达显著降低。miR26a 通过抑制 PTEN 和增加细胞活力及其数量来增强其对成骨细胞分化的作用，这是成骨细胞分化过程中的一个重要过程。我们的研究表明，上调 miR26a 可以增加骨形成，并且可能作为一个重要的靶点，进一步研究其在组织工程应用中的潜力。
