Obtaining differentiated cells with high physiological functions by an efficient, but simple and rapid differentiation method is crucial for modeling neuronal diseases in vitro using human pluripotent stem cells (hPSCs). Currently, methods involving the transient expression of one or a couple of transcription factors have been established as techniques for inducing neuronal differentiation in a rapid, single step. It has also been reported that microRNAs can function as reprogramming effectors for directly reprogramming human dermal fibroblasts to neurons. In this study, we tested the effect of adding neuronal microRNAs, miRNA-9/9*, and miR-124 (miR-9/9*-124), for the neuronal induction method of hPSCs using Tet-On-driven expression of the Neurogenin2 gene (Ngn2), a proneural factor. While it has been established that Ngn2 can facilitate differentiation from pluripotent stem cells into neurons with high purity due to its neurogenic effect, a long or indefinite time is required for neuronal maturation with Ngn2 misexpression alone. With the present method, the cells maintained a high neuronal differentiation rate while exhibiting increased gene expression of neuronal maturation markers, spontaneous calcium oscillation, and high electrical activity with network bursts as assessed by a multipoint electrode system. Moreover, when applying this method to iPSCs from Alzheimer’s disease (AD) patients with presenilin-1 (PS1) or presenilin-2 (PS2) mutations, cellular phenotypes such as increased amount of extracellular secretion of amyloid β42, abnormal oxygen consumption, and increased reactive oxygen species in the cells were observed in a shorter culture period than those previously reported. Therefore, it is strongly anticipated that the induction method combining Ngn2 and miR-9/9*-124 will enable more rapid and simple screening for various types of neuronal disease phenotypes and promote drug discovery.

Sepsis-associated encephalopathy (SAE) is a diffuse brain dysfunction resulting from a systemic inflammatory response to infection, but the mechanism remains unclear. The mitochondrial permeability transition pore (MPTP) could play a central role in the neuronal dysfunction, induction of apoptosis, and cell death in SAE. The mitochondrial isomerase cyclophilin D (CypD) is known to control the sensitivity of MPTP induction. We, therefore, established a cecal ligation and puncture (CLP) model, which is the gold standard in sepsis research, using CypD knockout (CypD KO) mice, and analyzed the disease phenotype and the possible molecular mechanism of SAE through metabolomic analyses of brain tissue. A comparison of adult, male wild-type, and CypD KO mice demonstrated statistically significant differences in body temperature, mortality, and histological changes. In the metabolomic analysis, the main finding was the maintenance of reduced glutathione (GSH) levels and the reduced glutathione/oxidized glutathione (GSH/GSSG) ratio in the KO animals following CLP. In conclusion, we demonstrate that CypD is implicated in the pathogenesis of SAE, possibly related to the inhibition of MPTP induction and, as a consequence, the decreased production of ROS and other free radicals, thereby protecting mitochondrial and cellular function.

Background/Objectives: Sepsis is a life-threatening condition characterized by organ dysfunction due to a dysregulated host response to infection. Mitochondrial dysfunction is considered a key contributor to the pathogenesis of sepsis, but its molecular mechanisms remain unclear. Methods: In this study, we used a cecal ligation and puncture (CLP) model to induce sepsis in wild-type (WT) and cyclophilin D knockout (CypD KO) mice. Liver tissues were collected at 0, 6, and 18 h post-CLP and analyzed using liquid chromatography–tandem mass spectrometry (LC-MS/MS). Results: Metabolomic profiling revealed that lactate levels significantly increased in the WT mice but remained stable in the KO mice. While AMP levels were preserved in the KO mice, these mice had significantly higher glutathione disulfide (GSSG) and spermidine concentrations than the WT mice at 18 h (p < 0.05). The levels of malondialdehyde (MDA), a marker of oxidative stress, were also significantly lower in the KO mice at 18 h (p < 0.05). These findings suggest that CypD deficiency preserves mitochondrial function, enhances resistance to oxidative stress, and mitigates septic liver injury. Conclusions: Our results highlight the potential of targeting mitochondrial permeability transition as a therapeutic strategy for sepsis.

Background/Objectives: In recent years, it has been suggested that sedatives may cause brain damage. One possible mechanism is interference with oxidative phosphorylation of brain mitochondria, but much remains unknown. In this study, we focused on dexmedetomidine, midazolam, and propofol, essential sedatives in anesthesia and intensive care, and aimed to understand the effects of these drugs on mouse brain mitochondria. Methods: We measured changes in mitochondrial respiratory capacity and swelling rate upon exposure to these sedatives in a wide concentration range. For the sedative that demonstrated impaired mitochondrial function we explored the possible involvement of mitochondrial permeability transition pore opening using brain mitochondria from cyclophilin D knockout (CypD KO) mice and detected cytochrome c (cyt c) release by Western blot. Results: Of the three sedatives, only high concentrations of propofol exhibited reduced respiratory capacity and mitochondrial swelling, toxicity which was not prevented by CypD KO. Furthermore, propofol did not induce cyt c release. Conclusions: These results suggest that propofol-induced brain mitochondrial dysfunction is a mechanism independent of mPTP opening.