Proteome analysis of human embryonic stem cells organelles.

As the functions of proteins are associated with their cellular localization, the comprehensive sub-cellular proteome knowledge of human embryonic stem cells (hESCs) is indispensable for ensuring a therapeutic effect. Here, we have utilized a sub-cellular proteomics approach to analyze the localization of proteins in the nucleus, mitochondria, crude membrane, cytoplasm, heavy and light microsomes. Out of 2002 reproducibly identified proteins, we detected 762 proteins in a single organelle whereas 160 proteins were found in all sub-cellular fractions. We verified the localization of identified proteins through databases and discussed the consistency of the obtained results. With regards to the ambiguity in the definition of a membrane protein, we tried to clearly define the plasma membrane, peripheral membrane and membrane proteins by annotation of these proteins in databases, along with predictions of transmembrane helices. Among ten enriched signaling pathways highlighted in our results, non-canonical Wnt signaling were analyzed in greater detail. The functions of three novel hESC membrane proteins (ERBB4, GGT1 and ZDHHC13) have been assessed in terms of pluripotency. Our report is the most comprehensive for organellar proteomics of hESCs. SIGNIFICANCE: Mass spectrometric identification of proteins using a TripleTOF 5600 from nucleus, mitochondria, crude membrane, cytoplasm, heavy and light microsomal fractions highlighted the significance of the non-canonical Wnt signaling in human embryonic stem cells.

Substrate-mediated commitment of human embryonic stem cells for hepatic differentiation.

Human embryonic stem cell (hESC)-derived endodermal cells are of interest for the development of cellular therapies to treat disorders such as liver failure. The soluble form of activin A (Act) has been widely used as an in vitro inducer of definitive endoderm (DE). In this study, we have developed a nanofibrous poly (ɛ-caprolactone) substrate, biofunctionalized with Act, for directed differentiation of hESCs into DE. Bioconjugation of Act on nanofibrous meshes was confirmed by enzyme-linked immunosorbent assay (ELISA) and immunostaining. In order to investigate the bioactivity of immobilized Act (iAct), hESCs were cultivated on the Act-conjugated nanofibers for five days. The nanofibers with covalent iAct significantly increased expression levels of the endodermal markers SOX17, FOXA2, and CXCR4, compared with physically adsorbed Act (aAct) or without Act (noAct). In addition, iAct retained its bioactivity after storage for five days in the absence of cell seeding. The capability of cultivated cells to generate the DE-derived lineage was evaluated through further differentiation of seeded cells into hepatocyte-like cells (HLCs). Interestingly, the iAct sample showed a higher level of hepatic markers compared to the aAct sample. We also demonstrated that iAct in the presence of soluble Act (sAct) could improve the conventional protocol to generate HLCs from hESCs. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2861-2872, 2016.

A Universal and Robust Integrated Platform for the Scalable Production of Human Cardiomyocytes From Pluripotent Stem Cells.

UNLABELLED: Recent advances in the generation of cardiomyocytes (CMs) from human pluripotent stem cells (hPSCs), in conjunction with the promising outcomes from preclinical and clinical studies, have raised new hopes for cardiac cell therapy. We report the development of a scalable, robust, and integrated differentiation platform for large-scale production of hPSC-CM aggregates in a stirred suspension bioreactor as a single-unit operation. Precise modulation of the differentiation process by small molecule activation of WNT signaling, followed by inactivation of transforming growth factor-ß and WNT signaling and activation of sonic hedgehog signaling in hPSCs as size-controlled aggregates led to the generation of approximately 100% beating CM spheroids containing virtually pure (∼90%) CMs in 10 days. Moreover, the developed differentiation strategy was universal, as demonstrated by testing multiple hPSC lines (5 human embryonic stem cell and 4 human inducible PSC lines) without cell sorting or selection. The produced hPSC-CMs successfully expressed canonical lineage-specific markers and showed high functionality, as demonstrated by microelectrode array and electrophysiology tests. This robust and universal platform could become a valuable tool for the mass production of functional hPSC-CMs as a prerequisite for realizing their promising potential for therapeutic and industrial applications, including drug discovery and toxicity assays. SIGNIFICANCE: Recent advances in the generation of cardiomyocytes (CMs) from human pluripotent stem cells (hPSCs) and the development of novel cell therapy strategies using hPSC-CMs (e.g., cardiac patches) in conjunction with promising preclinical and clinical studies, have raised new hopes for patients with end-stage cardiovascular disease, which remains the leading cause of morbidity and mortality globally. In this study, a simplified, scalable, robust, and integrated differentiation platform was developed to generate clinical grade hPSC-CMs as cell aggregates under chemically defined culture conditions. This approach resulted in approximately 100% beating CM spheroids with virtually pure (∼90%) functional cardiomyocytes in 10 days from multiple hPSC lines. This universal and robust bioprocessing platform can provide sufficient numbers of hPSC-CMs for companies developing regenerative medicine technologies to rescue, replace, and help repair damaged heart tissues and for pharmaceutical companies developing advanced biologics and drugs for regeneration of lost heart tissue using high-throughput technologies. It is believed that this technology can expedite clinical progress in these areas to achieve a meaningful impact on improving clinical outcomes, cost of care, and quality of life for those patients disabled and experiencing heart disease.

Bioprocess development for mass production of size-controlled human pluripotent stem cell aggregates in stirred suspension bioreactor.

Current protocols for the scalable suspension culture of human pluripotent stem cells (hPSCs) are limited by multiple biological and technical challenges that need to be addressed before their use in clinical trials. To overcome these challenges, we have developed a novel bioprocess platform for large-scale expansion of human embryonic and induced pluripotent stem cell lines as three-dimensional size-controlled aggregates. This novel bioprocess utilizes the stepwise optimization of both static and dynamic suspension culture conditions. After screening eight xeno-free media in static suspension culture and optimizing single-cell passaging in dynamic conditions, the scale-up from a static to a dynamic suspension culture in the stirred bioreactor resulted in a two- to threefold improvement in expansion rates, as measured by cell counts and metabolic activity. We successfully produced size-specific aggregates through optimization of bioreactor hydrodynamic conditions by using combinations of different agitation rates and shear protectant concentrations. The expansion rates were further improved by controlling oxygen concentration at normoxic conditions, and reached a maximum eightfold increase for both types of hPSCs. Subsequently, we demonstrated a simple and rapid scale-up strategy that produced clinically relevant numbers of hPSCs (∼2×10(9) cells) over a 1-month period by the direct transfer of "suspension-adapted frozen cells" to a stirred suspension bioreactor. We omitted the required preadaptation passages in the static suspension culture. The cells underwent proliferation over multiple passages in the demonstrated xeno-free dynamic suspension culture while maintaining their self-renewal capabilities, as determined by marker expressions and in vitro spontaneous differentiation. In conclusion, suspension culture protocols of hPSCs could be used to mass produce homogenous and pluripotent undifferentiated cells by identification and optimization of key bioprocess parameters that are complemented by a simple and rapid scale-up platform.

Protocol for expansion of undifferentiated human embryonic and pluripotent stem cells in suspension.

Human embryonic and induced pluripotent stem cells (hESCs and hiPSCs) offer a platform technology with the potential for developmental biology and cell-based therapy. Therefore, robust and cost-effective ways for mass production of them is necessary. Here, we have presented a protocol to grow pluripotent hESCs and hiPSCs in suspension by using a simple, inexpensive, microcarrier-free method. Under this condition, the cells maintained stability during freeze/thaw cycles without the loss of pluripotency markers for extended periods (>1 year). The cells maintained a stable karyotype and showed very similar expression profiles when compared to the adherent culture. The combination of this system with a bioreactor culture system will allow scale up culture of hESCs and hiPSCs needed for clinical and translational applications.

Simultaneous suppression of TGF-ß and ERK signaling contributes to the highly efficient and reproducible generation of mouse embryonic stem cells from previously considered refractory and non-permissive strains.

Mouse embryonic stem cells (ESCs) are pluripotent stem cell lines derived from pre-implantation embryos. The efficiency of mESC generation is affected by genetic variation in mice; that is, some mouse strains are refractory or non-permissive to ESC establishment. Developing an efficient method to derive mESCs from strains of various genetic backgrounds should be valuable for establishment of ESCs in various mammalian species. In the present study, we identified dual inhibition of TGF-ß and ERK1/2, by SB431542 and PD0325901, respectively led to the highly efficient and reproducible generation of mESC lines from NMRI, C57BL/6, BALB/c, DBA/2, and FVB/N strains, which previously considered refractory or non-permissive for ESC establishment. These mESCs expressed pluripotency markers and retained the capacity to differentiate into derivatives of all three germ layers. The evaluated lines exhibited high rates of chimerism when reintroduced into blastocysts. To our knowledge, this is the first report of efficient (100%) mESC lines generation from different genetic backgrounds. The application of these two inhibitors will not only solve the problems of mESC derivation but also clarifies new signaling pathways in pluripotent mESCs.

Long-term maintenance of undifferentiated human embryonic and induced pluripotent stem cells in suspension.

Traditionally, undifferentiated pluripotent human embryonic and induced pluripotent stem cells (hESCs and hiPSCs) have been expanded as monolayer colonies in adhesion culture, both in the presence or absence of feeder cells. However, the use of pluripotent stem cells poses the need to scale-up current culture methods. Herein, we present the cultivation of 2 hESC lines (Royan H5 and Royan H6) and 2 hiPSC lines (hiPSC1 and hiPSC4) as carrier-free suspension aggregates for an extended period of time. The cells proliferated over multiple passages kept a stable karyotype, which successfully maintained an undifferentiated state and pluripotency, as determined by marker expressions in addition to in vitro spontaneous and directed differentiation. Additionally, these cells can be easily frozen and thawed without losing their proliferation, karyotype stability, and developmental potential. Transcriptome analysis of the 3 lines revealed that the adherent culture condition was nearly identical to the suspension culture in Royan H5 and hiPSC1, but not in Royan H6. It remains unclear whether this observation at the transcript level is biologically significant. In comparison with recent reports, our study presents a low-cost procedure for long-term suspension expansion of hESCs and hiPSCs with the capability of freeze/thawing, karyotype stability, and pluripotency. Our results will pave the way for scaled up expansion and controlled differentiation of hESCs and hiPSCs needed for cell therapy, research, and industrial applications in a bioreactor culture system.

Nuclear proteome analysis of monkey embryonic stem cells during differentiation.

The nuclear proteome enables, manages, and regulates the genome by the collective actions and interactions of proteins found in the nucleus. We applied a proteomic approach to analyze a nuclear proteome during embryonic stem cell (ESC) proliferation, and 3 and 9 days after initiation of differentiation. The nuclei were isolated from cells and their proteins were separated using 2-DE. Out of about 560 protein spots reproducible detected on any give gel, 49 differentially expressed proteins were identified by Matrix Assisted Laser Desorption Ionization-Time of Flight (MALDI TOF/TOF) mass spectrometry. Of them, several nuclear located proteins involved in chromatin remodeling, transcription regulation, apoptosis, cell proliferation, and differentiation were identified including CTBP1, MM-1, RUVBL1, HCC-1, SGTA, SUMO2, and Galectin-1. Functional interaction analysis of differentially expressed proteins revealed that most of nuclear proteins had a direct interaction with c-Myc and p53.