Dental pulp-derived stem cells can counterbalance peripheral nerve injury-induced oxidative stress and supraspinal neuro-inflammation in rat brain

Previously, we reported the successful regeneration of injured peripheral nerves using human dental pulp stem cells (DPSCs) or differentiated neuronal cells from DPSCs (DF-DPSCs) in a rat model. Here, we attempted to evaluate oxidative stress and supraspinal neuro-inflammation in rat brain after sciatic nerve injury (SNI). We divided our experimental animals into three SNI groups based on time. The expression of a microglial (Iba1) marker and reactive oxygen species (ROS) was lower in DPSCs and higher in DF-DPSCs. In contrast, the expression of an astroglial (GFAP) marker was higher in DPSCs and lower in DF-DPSCs at 2 weeks. However, the expression of ROS, Iba1 and GFAP gradually decreased at 8 and 12 weeks in the SNI DPSCs and DF-DPSCs groups compared to the SNI control. Furthermore, anti-inflammatory cytokine (IL-4 and TGF-β) expression was lower at 2 weeks, while it gradually increased at 8 and 12 weeks after surgery in the SNI DPSCs and DF-DPSCs groups. Similarly, SNI DPSCs had a high expression of pAMPK, SIRT1 and NFkB at the onset of SNI. However, 12 weeks after surgery, pAMPK and SIRT1 expression levels were higher and NFkB was down-regulated in both DPSCs and DF-DPSCs compared to the control group. Finally, we concluded that DPSCs responded early and more efficiently than DF-DPSCs to counterbalance peripheral nerve injury (PNI)-induced oxidative stress and supraspinal neuro-inflammation in rat brain.