期刊
STEM CELL REVIEWS AND REPORTS
卷 18, 期 3, 页码 1078-1096出版社
SPRINGER
DOI: 10.1007/s12015-021-10219-6
关键词
Mesenchymal stem cells; Transforming growth factor beta; Smad 6; Neural stem cells; Spinal cord injury
资金
- National Natural Science Foundation of China [81472088]
- Natural Science Foundation of Anhui Province [1608085MH205]
The study showed that EVs from MSCs can upregulate Smad 6 expression in NSCs by carrying TGF-beta, promoting neural differentiation. Early inhibition of TGF-beta did not increase neuron regrowth in spinal cord injury, but later treatment with TGF-beta inhibitor improved the neurological outcome by promoting neuron regrowth.
Mesenchymal stem cells (MSCs) constitute a promising therapy for spinal cord injury (SCI) because they can provide a favorable environment for the regrowth of neurons by inhibiting receptor-regulated Smads (R-Smads) expression in endogenous neural stem cells (NSCs). However, their mechanism of action and effect on the expression of inhibitory Smads (I-Smads) remain unclear. Herein, we demonstrated that extracellular vesicles (EVs) from MSCs were able to upregulate the Smad 6 expression by carrying TGF-beta, and the Smad 6 knockdown in NSCs partially weakened the bone marrow MSC (BMSC)-EV-induced effect on neural differentiation. We found that the expression of Smad 6 did not reduced owing to the TGF-beta type I receptor kinase inhibitor, SB 431,542, treatment in the acute phase of injury in rats with SCI, thereby indicating that the Smad 6 expression was not only mediated by TGF-beta, but also by the inflammatory factors and bone morphogenetic proteins (BMPs) as well. However, in the later phase of SCI, the Smad 6 expression decreased by the addition of SB 431,542, suggesting that TGF-beta plays a key role in the mediation of Smad 6 expression in this phase. In addition, immunohistochemistry staining; hematoxylin-eosin staining; and the Basso, Beattie, and Bresnahan (BBB) scores revealed that the early inhibition of TGF-beta did not increase neuron regrowth. However, this inhibition increased the cavity and the caspase-3 expression at 24 h post-injury, leading to a worse functional outcome. Conversely, the later treatment with the TGF-beta inhibitor promoted the regrowth of neurons around the cavity, resulting in a better neurological outcome. Together, these results indicate that Smad 6 acts as a feedback regulator to prevent the over-differentiation of NSCs to astrocytes and that BMSC-EVs can upregulate Smad 6 expression by carrying TGF-beta.
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