Differentiation of Midbrain Dopaminergic Neurons from Human iPS Cells

Inhibition of ceramide synthesis improves the outcome of ischemia/reperfusion injury in cardiomyocytes derived from human induced pluripotent stem cell

BACKGROUND

Ceramides are bioactive sphingolipids that have physiological effects on inflammation, apoptosis, and mitochondrial dysfunction. They may play a critical role in the harm of ischemia/reperfusion (IR). Ceramides and IR injury are not well-studied, and there is a lack of human data.

METHODS AND RESULTS

Current studies aimed to investigate the role of ceramide buildup in cardiomyocytes (CMs) death using CMs derived from human induced pluripotent stem cell (hiPSC) as a model for simulating IR injury in vitro. In our model, serum- and glucose-free media was used to expose hiPSC-derived CMs to hypoxia (3% O2) for 6 h (hrs), followed by reoxygenation (20% O2) for 16 h. In contrast to normoxia (control) or hypoxia (ischemia), our data showed that following IR, there was an increase in the formation of mitochondrial superoxide and the mRNA levels of genes regulating ceramide synthesis, such as CerS2 and CerS4 in CMs. Further, there was a considerable rise in the levels of total ceramide, long-chain (C16:0, C18:0, and C18:1), and very long-chain (C22:0 and C24:1) ceramide species in CMs following reperfusion in comparison to control or ischemic CMs. Interestingly, compared to CMs exposed to IR without inhibitor, our data showed that inhibition of ceramide formation with fumonisin B1 (FB1) significantly lowered ceramide levels, reduced apoptosis, improved mitochondrial function, and enhanced survival of CMs exposed to IR. Furthermore, we used a transgenic mouse model, in which the CerS2 gene was overexpressed in the CMs of α-MHC-CerS2 mice, to validate the basic idea that ceramide contributes to heart disease in vivo. Our results showed that the heart tissues of α-MHC-CerS2 mice had significant levels of long-chain and very long-chain ceramides, which causes increased apoptosis, proinflammatory cytokines, interstitial inflammatory cell infiltration, and collagen deposition.

CONCLUSIONS

Results from both in vitro and in vivo experiments show that ceramides have a significant role in either mediating or inducing damage to CMs. Additionally, in vitro findings show that ceramide reduction improves the outcome of IR injury by lowering intracellular Ca2+ [Ca2+]i concentration and improves mitochondrial function changes during IR.

Shedding light on latent pathogenesis and pathophysiology of mental disorders: The potential of iPS cell technology

Mental disorders are considered as one of the major healthcare issues worldwide owing to their significant impact on the quality of life of patients, causing serious social burdens. However, it is hard to examine the living brain-a source of psychiatric symptoms-at the cellular, subcellular, and molecular levels, which poses difficulty in determining the pathogenesis and pathophysiology of mental disorders. Recently, induced pluripotent stem cell (iPSC) technology has been used as a novel tool for research on mental disorders. We believe that the iPSC-based studies will address the limitations of other research approaches, such as human genome, postmortem brain study, brain imaging, and animal model analysis. Notably, studies using integrated iPSC technology with genetic information have provided significant novel findings to date. This review aimed to discuss the history, current trends, potential, and future of iPSC technology in the field of mental disorders. Although iPSC technology has several limitations, this technology can be used in combination with the other approaches to facilitate studies on mental disorders.

From 2D to 3D: Development of Monolayer Dopaminergic Neuronal and Midbrain Organoid Cultures for Parkinson's Disease Modeling and Regenerative Therapy

Parkinson's Disease (PD) is a prevalent neurodegenerative disorder that is characterized pathologically by the loss of A9-specific dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc) of the midbrain. Despite intensive research, the etiology of PD is currently unresolved, and the disease remains incurable. This, in part, is due to the lack of an experimental disease model that could faithfully recapitulate the features of human PD. However, the recent advent of induced pluripotent stem cell (iPSC) technology has allowed PD models to be created from patient-derived cells. Indeed, DA neurons from PD patients are now routinely established in many laboratories as monolayers as well as 3D organoid cultures that serve as useful toolboxes for understanding the mechanism underlying PD and also for drug discovery. At the same time, the iPSC technology also provides unprecedented opportunity for autologous cell-based therapy for the PD patient to be performed using the patient's own cells as starting materials. In this review, we provide an update on the molecular processes underpinning the development and differentiation of human pluripotent stem cells (PSCs) into midbrain DA neurons in both 2D and 3D cultures, as well as the latest advancements in using these cells for drug discovery and regenerative medicine. For the novice entering the field, the cornucopia of differentiation protocols reported for the generation of midbrain DA neurons may seem daunting. Here, we have distilled the essence of the different approaches and summarized the main factors driving DA neuronal differentiation, with the view to provide a useful guide to newcomers who are interested in developing iPSC-based models of PD.

Quality criteria for in vitro human pluripotent stem cell-derived models of tissue-based cells

The advent of the technology to isolate or generate human pluripotent stem cells provided the potential to develop a wide range of human models that could enhance understanding of mechanisms underlying human development and disease. These systems are now beginning to mature and provide the basis for the development of in vitro assays suitable to understand the biological processes involved in the multi-organ systems of the human body, and will improve strategies for diagnosis, prevention, therapies and precision medicine. Induced pluripotent stem cell lines are prone to phenotypic and genotypic changes and donor/clone dependent variability, which means that it is important to identify the most appropriate characterization markers and quality control measures when sourcing new cell lines and assessing differentiated cell and tissue culture preparations for experimental work. This paper considers those core quality control measures for human pluripotent stem cell lines and evaluates the state of play in the development of key functional markers for their differentiated cell derivatives to promote assurance of reproducibility of scientific data derived from pluripotent stem cell-based systems.