Cisplatin induces differentiation in teratomas derived from pluripotent stem cells

Introduction

Currently, embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) can be induced to differentiate at the cellular level but not to form mature tissues or organs suitable for transplantation. ESCs/iPSCs form immature teratomas after injection into immunodeficient mice. In humans, immature teratomas often transform into fully differentiated mature teratomas after administration of anticancer agents.

Methods

We first investigated the ability of cisplatin to induce changes in mouse ESCs/iPSCs in vitro. Next, we designed experiments to analyze ESC/iPSC-derived immature teratoma tissue in vivo after treatment of cisplatin. Groups of six mice carrying ESC- or iPSC-derived teratomas were given either low or high dose intraperitoneal injection of cisplatin, while the control group received saline for 4 weeks.

Results

Treatment of ESC/iPSC cultures with cisplatin for 3 days caused a dose-related decrease in cell numbers without inducing any morphological changes to the cells. ESC/iPSC-derived teratomas showed lower growth rates with a significantly higher mature components ratio in a concentration dependent manner after cisplatin treatment (P < 0.05); however, immunohistochemical analyses demonstrated a significantly reduced PCNA labelling index and an increase in an apoptosis marker on immature neural components (P < 0.05) along with emergence of h-Caldesmon⁺ mature smooth muscle cells in treated mice. Moreover, newly differentiated components not found in the control group, such as mature adipose tissue, cartilage, and pancreas, as well as striated muscle, salivary glands, gastric mucosa with fundic glands, and hair follicles emerged. The identities of these components were confirmed by immunostaining for specific markers.

Conclusions

Cisplatin has the ability to reduce immature components in ESC/iPSC-derived teratomas, presumably through apoptosis, and also to induce them to differentiate.

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Transformation of immature to mature teratoma after chemotherapy was verified.

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Mice bearing ESC/iPSC-derived immature teratomas were used.

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Mice were treated with intraperitoneal injection of cisplatin for 4 weeks.

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Newly differentiated structures were found only in the tumors of treated mice.

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Cisplatin can induce differentiation in ESC/iPSC-derived immature teratomas.

Endodermal differentiation of human induced pluripotent stem cells using simple dialysis culture system in suspension culture

A differentiation of human induced pluripotent stem cells (hiPSCs) into definitive endoderm linage is required for a preparation of metabolic organ derived cells. The differentiation consumed high-priced cytokines and small molecules, which have hampered the manufacturability of differentiated cells. Although the cytokines and small molecules are remained or cells produce the autocrine factors, daily culture medium change should be proceeded to remove toxic metabolites generated from cells. In this study, we developed a simple dialysis culture system to refine the medium during definitive endodermal differentiation. We demonstrated that dialysis culture prevented cell damage to remove lactate. The hiPSCs cultured with dialysis also differentiated similarly as usual differentiation without dialysis even if they were not supplied Activin A for latter culture days in the differentiation. With this dialysis culture system, hiPSCs were differentiated into endodermal lineage with medium refinement and recycling and autocrine factors as well as cytokines, which may lead to reduce differentiation cost.

Analysis of essential pathways for self-renewal in common marmoset embryonic stem cells

Common marmoset (CM) is widely recognized as a useful non-human primate for disease modeling and preclinical studies. Thus, embryonic stem cells (ESCs) derived from CM have potential as an appropriate cell source to test human regenerative medicine using human ESCs. CM ESCs have been established by us and other groups, and can be cultured in vitro. However, the growth factors and downstream pathways for self-renewal of CM ESCs are largely unknown. In this study, we found that basic fibroblast growth factor (bFGF) rather than leukemia inhibitory factor (LIF) promoted CM ESC self-renewal via the activation of phosphatidylinositol-3-kinase (PI3K)-protein kinase B (AKT) pathway on mouse embryonic fibroblast (MEF) feeders. Moreover, bFGF and transforming growth factor β (TGFβ) signaling pathways cooperatively maintained the undifferentiated state of CM ESCs under feeder-free condition. Our findings may improve the culture techniques of CM ESCs and facilitate their use as a preclinical experimental resource for human regenerative medicine.