Reconsidering pluripotency tests: do we still need teratoma assays?

A human pluripotent stem cell surface N-glycoproteome resource reveals markers, extracellular epitopes, and drug targets

Detailed knowledge of cell-surface proteins for isolating well-defined populations of human pluripotent stem cells (hPSCs) would significantly enhance their characterization and translational potential. Through a chemoproteomic approach, we developed a cell-surface proteome inventory containing 496 N-linked glycoproteins on human embryonic (hESCs) and induced PSCs (hiPSCs). Against a backdrop of human fibroblasts and 50 other cell types, >100 surface proteins of interest for hPSCs were revealed. The >30 positive and negative markers verified here by orthogonal approaches provide experimental justification for the rational selection of pluripotency and lineage markers, epitopes for cell isolation, and reagents for the characterization of putative hiPSC lines. Comparative differences between the chemoproteomic-defined surfaceome and the transcriptome-predicted surfaceome directly led to the discovery that STF-31, a reported GLUT-1 inhibitor, is toxic to hPSCs and efficient for selective elimination of hPSCs from mixed cultures.

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496 cell surface N-glycoproteins on hPSCs

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N-glycosylation site identification dictates accessible epitopes

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>30 positive and negative selection markers for hPSCs are validated

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STF-31 is selectively toxic to hPSCs

A mystery unraveled: nontumorigenic pluripotent stem cells in human adult tissues

INTRODUCTION

Embryonic stem cells and induced pluripotent stem cells have emerged as the gold standard of pluripotent stem cells and the class of stem cell with the highest potential for contribution to regenerative and therapeutic application; however, their translational use is often impeded by teratoma formation, commonly associated with pluripotency. We discuss a population of nontumorigenic pluripotent stem cells, termed Multilineage Differentiating Stress Enduring (Muse) cells, which offer an innovative and exciting avenue of exploration for the potential treatment of various human diseases.

AREAS COVERED

This review discusses the origin of Muse cells, describes in detail their various unique characteristics, and considers future avenues of their application and investigation with respect to what is currently known of adult pluripotent stem cells in scientific literature. We begin by defining cell potency, then discuss both mesenchymal and various reported populations of pluripotent stem cells, and finally delve into Muse cells and the characteristics that set them apart from their contemporaries.

EXPERT OPINION

Muse cells derived from adipose tissue (Muse-AT) are efficiently, routinely and painlessly isolated from human lipoaspirate material, exhibit tripoblastic differentiation both spontaneously and under media-specific induction, and do not form teratomas. We describe qualities specific to Muse-AT cells and their potential impact on the field of regenerative medicine and cell therapy.

Considerations for pre-clinical models and clinical trials of pluripotent stem cell-derived cardiomyocytes

Pluripotent stem cells (PSCs) represent an appealing source from which to develop cell replacement therapies. Different initiatives have been launched to promote their development toward clinical applications. This article will review the main questions that should be considered before translating PSC-derived cardiomyocytes into clinical investigations, including the development of good manufacturing practice-level PSC lines, the development of efficient protocols to generate pure populations of cardiac myocytes, and the development of techniques to improve the retention and survival rate of transplanted cells.

Gammaretroviral vector encoding a fluorescent marker to facilitate detection of reprogrammed human fibroblasts during iPSC generation

Induced pluripotent stem cells (iPSCs) are becoming mainstream tools to study mechanisms of development and disease. They have a broad range of applications in understanding disease processes, in vitro testing of novel therapies, and potential utility in regenerative medicine. Although the techniques for generating iPSCs are becoming more straightforward, scientists can expend considerable resources and time to establish this technology. A major hurdle is the accurate determination of valid iPSC-like colonies that can be selected for further cloning and characterization. In this study, we describe the use of a gammaretroviral vector encoding a fluorescent marker, mRFP1, to not only monitor the efficiency of initial transduction but also to identify putative iPSC colonies through silencing of mRFP1 gene as a consequence of successful reprogramming.