Mitochondrial Transfer of Wharton's Jelly Mesenchymal Stem Cells Eliminates Mutation Burden and Rescues Mitochondrial Bioenergetics in Rotenone-Stressed MELAS Fibroblasts.

Wharton's jelly mesenchymal stem cells (WJMSCs) transfer healthy mitochondria to cells harboring a mitochondrial DNA (mtDNA) defect. Mitochondrial myopathy, encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) is one of the major subgroups of mitochondrial diseases, caused by the mt.3243A>G point mutation in the mitochondrial tRNALeu(UUR) gene. The specific aim of the study is to investigate whether WJMSCs exert therapeutic effect for mitochondrial dysfunction in cells of MELAS patient through donating healthy mitochondria. We herein demonstrate that WJMSCs transfer healthy mitochondria into rotenone-stressed fibroblasts of a MELAS patient, thereby eliminating mutation burden and rescuing mitochondrial functions. In the coculture system in vitro study, WJMSCs transferred healthy mitochondria to rotenone-stressed MELAS fibroblasts. By inhibiting actin polymerization to block tunneling nanotubes (TNTs), the WJMSC-conducted mitochondrial transfer was abrogated. After mitochondrial transfer, the mt.3243A>G mutation burden of MELAS fibroblasts was reduced to an undetectable level, with long-term retention. Sequencing results confirmed that the transferred mitochondria were donated from WJMSCs. Furthermore, mitochondrial transfer of WJMSCs to MELAS fibroblasts improves mitochondrial functions and cellular performance, including protein translation of respiratory complexes, ROS overexpression, mitochondrial membrane potential, mitochondrial morphology and bioenergetics, cell proliferation, mitochondrion-dependent viability, and apoptotic resistance. This study demonstrates that WJMSCs exert bioenergetic therapeutic effects through mitochondrial transfer. This finding paves the way for the development of innovative treatments for MELAS and other mitochondrial diseases.

Mitochondrial Transfer from Wharton's Jelly Mesenchymal Stem Cell to MERRF Cybrid Reduces Oxidative Stress and Improves Mitochondrial Bioenergetics.

Myoclonus epilepsy associated with ragged-red fibers (MERRF) is a maternally inherited mitochondrial disease affecting neuromuscular functions. Mt.8344A>G mutation in mitochondrial DNA (mtDNA) is the most common cause of MERRF syndrome and has been linked to an increase in reactive oxygen species (ROS) level and oxidative stress, as well as impaired mitochondrial bioenergetics. Here, we tested whether WJMSC has therapeutic potential for the treatment of MERRF syndrome through the transfer of mitochondria. The MERRF cybrid cells exhibited a high mt.8344A>G mutation ratio, enhanced ROS level and oxidative damage, impaired mitochondrial bioenergetics, defected mitochondria-dependent viability, exhibited an imbalance of mitochondrial dynamics, and are susceptible to apoptotic stress. Coculture experiments revealed that mitochondria were intercellularly conducted from the WJMSC to the MERRF cybrid. Furthermore, WJMSC transferred mitochondria exclusively to cells with defective mitochondria but not to cells with normal mitochondria. MERRF cybrid following WJMSC coculture (MF+WJ) demonstrated improvement of mt.8344A>G mutation ratio, ROS level, oxidative damage, mitochondrial bioenergetics, mitochondria-dependent viability, balance of mitochondrial dynamics, and resistance against apoptotic stress. WJMSC-derived mitochondrial transfer and its therapeutic effect were noted to be blocked by F-actin depolymerizing agent cytochalasin B. Collectively, the WJMSC ability to rescue cells with defective mitochondrial function through donating healthy mitochondria may lead to new insights into the development of more efficient strategies to treat diseases related to mitochondrial dysfunction.

Oncostatin M-dependent Mcl-1 induction mediated by JAK1/2-STAT1/3 and CREB contributes to bioenergetic improvements and protective effects against mitochondrial dysfunction in cortical neurons.

Oncostatin M (OSM), a cytokine in the interleukin-6 (IL-6) family, has been proposed to play a protective role in the central nervous system, such as attenuation of excitotoxicity induced by N-methyl-D-aspartate (NMDA) and glutamate. However, the potential neuroprotective effects of OSM against mitochondrial dysfunction have never been reported. In the present study, we tested the hypothesis that OSM may confer neuronal resistance against 3-nitropropionic acid (3-NP), a plant toxin that irreversibly inhibits the complex II of the mitochondrial electron transport chain, and characterized the underlying molecular mechanisms. We found that OSM preconditioning dose- and time-dependently protected cortical neurons against 3-NP toxicity. OSM stimulated expression of myeloid cell leukemia-1 (Mcl-1), an anti-apoptotic Bcl-2 family member expressed in differentiating myeloid cells, that required prior phosphorylation of Janus kinase-1 (JAK1), JAK2, extracellular signal-regulated kinase-1/2 (ERK1/2), signal transducer and activator of transcription-3 (STAT3), STAT1, and cAMP-response element-binding protein (CREB). Pharmacological inhibitors of JAK1, JAK2, ERK1/2, STAT3, STAT1, and CREB as well as the siRNA targeting at STAT3 and Mcl-1 all abolished OSM-dependent 3-NP resistance. Finally, OSM-dependent Mcl-1 induction contributed to the enhancements of mitochondrial bioenergetics including increases in spare respiratory capacity and ATP production. In conclusion, our findings indicated that OSM induces Mcl-1 expression via activation of ERK1/2, JAK1/2, STAT1/3, and CREB; furthermore, OSM-mediated Mcl-1 induction contributes to bioenergetic improvements and neuroprotective effects against 3-NP toxicity in cortical neurons. OSM may thus serve as a novel neuroprotective agent against mitochondrial dysfunction commonly associated with pathogenic mechanisms underlying neurodegeneration.

Clinical significance of serological biomarkers and neuropsychological performances in patients with temporal lobe epilepsy.

BACKGROUND: Temporal lobe epilepsy (TLE) is a common form of focal epilepsy. Serum biomarkers to predict cognitive performance in TLE patients without psychiatric comorbidities and the link with gray matter (GM) atrophy have not been fully explored. METHODS: Thirty-four patients with TLE and 34 sex - and age-matched controls were enrolled for standardized cognitive tests, neuroimaging studies as well as measurements of serum levels of heat shock protein 70 (HSP70), S100ß protein (S100ßP), neuronal specific enolase (NSE), plasma nuclear and mitochondrial DNA levels. RESULTS: Compared with the controls, the patients with TLE had poorer cognitive performances and higher HSP70 and S100ßP levels (p < 0.01). The patients with higher frequencies of seizures had higher levels of HSP70, NSE and S100ßP (p < 0.01). Serum HSP70 level correlated positively with duration of epilepsy (σ = 0.413, p < 0.01), and inversely with memory scores in the late registration (σ = -0.276, p = 0.01) and early recall score (σ = -0.304, p = 0.007). Compared with the controls, gray matter atrophy in the hippocampal and parahippocampal areas, putamen, thalamus and supplementary motor areas were found in the patient group. The HSP70 levels showed an inverse correlation with hippocampal volume (R square = 0.22, p = 0.007) after controlling for the effect of age. CONCLUSIONS: Our results suggest that serum biomarkers were predictive of higher frequencies of seizures in the TLE group. HSP70 may be considered to be a stress biomarker in patients with TLE in that it correlated inversely with memory scores and hippocampal volume. In addition, the symmetric extratemporal atrophic patterns may be related to damage of neuronal networks and epileptogenesis in TLE.