Min Jung Kim

Min Jung Kim, Ji Yeon Kim, Yun Hee Lim, Sung Jun Hong, Jae Hun Jeong, Hey Ran Choi, Sun Kyung Park, Jung Eun Kim, Min Ki Lee, and Jae Hun Kim. Korean J Pain 2022;35:475-87. https://doi.org/10.3344/kjp.2022.35.4.475

Sewon Park, Minjung Kim, and Jae Hun Kim. Korean J Pain 2022;35:129-39. https://doi.org/10.3344/kjp.2022.35.2.129

Background: Although spinal cord stimulation (SCS) can be a treatment option for intractable postherpetic neuralgia (PHN), obtaining proper stimulation at the thoracic dermatome is difficult. Dorsal root ganglion (DRG) stimulation may be an effective treatment for patients with insufficient efficacy in SCS only.Case: A 54-year-old man with intractable PHN was referred to our clinic. Pain was localized to the distribution of the T1–3 dermatomes. SCS trial was conducted, and lead was placed within the epidural space over the C6–T1 level; however, the stimulation was inadequate for his pain site. Therefore, another lead was placed within the left T1 and T2 DRG for trial, and T1 DRG stimulation provided adequate stimulation. T1 DRG stimulation and SCS could cover the entire pain site with paresthesia, and his pain was decreased by over 50%.Conclusions: DRG stimulation combined with SCS may be a good treatment option for intractable thoracic PHN.

Differentiated somatic cells can be reprogrammed into pluripotent stem cells by transduction of exogenous reprogramming factors. After induced pluripotent stem (iPS) cells are established, exogenous genes are silenced. In the pluripotent state, retroviral genes integrated in the host genome are kept inactive through epigenetic transcriptional regulation. In this study, we tried to determine whether exogenous genes remain silenced or are reactivated upon loss of pluripotency or on differentiation using an in vitro system. We induced differentiation of iPS cells into neural stem cells (NSCs) in vitro; the NSCs appeared morphologically indistinguishable from brain-derived NSCs and stained positive for the NSC markers Nestin and Sox2. These iPS cell-derived NSCs (iPS-NSCs) were also capable of differentiating into all three neural subtypes. Interestingly, iPS-NSCs spontaneously formed aggregates on long-term culture and showed reactivation of the Oct4-GFP marker, which was followed by the formation of embryonic stem cell-like colonies. The spontaneously reverted green fluorescent protein (GFP)-positive (iPS-NSC-GFP+) cells expressed high levels of pluripotency markers (Oct4 and Nanog) and formed germline chimeras, indicating that iPS-NSC-GFP+ cells had the same pluripotency as the original iPS cells. The reactivation of silenced exogenous genes was tightly correlated with the downregulation of DNA methyltransferases (Dnmts) during differentiation of iPS cells. This phenomenon was not observed in doxycycline-inducible iPS cells, where the reactivation of exogenous genes could be induced only by doxycycline treatment. These results indicate that pluripotency can be regained through reactivation of exogenous genes, which is associated with dynamic change of Dnmt levels during differentiation of iPS cells. Stem Cells 2014;32:2596–2604