Clonal expansion of human pluripotent stem cells on gelatin-coated surface

Improving In Vitro Culture of Human Male Fetal Germ Cells

Male human fetal germ cells (hFGCs) give rise to spermatogonial stem cells (SSCs), which are the adult precursors of the male gametes. Human SSCs are a promising (autologous) source of cells for male fertility preservation; however, in contrast to mouse SSCs, we are still unable to culture them in the long term. Here, we investigated the effect of two different culture media and four substrates (laminin, gelatin, vitronectin and matrigel) in the culture of dissociated second trimester testes, enriched for hFGCs. After 6 days in culture, we quantified the presence of POU5F1 and DDX4 expressing hFGCs. We observed a pronounced difference in hFGC number in different substrates. The combination of gelatin-coated substrate and medium containing GDNF, LIF, FGF2 and EGF resulted in the highest percentage of hFGCs (10% of the total gonadal cells) after 6 days of culture. However, the vitronectin-coated substrate resulted in a comparable percentage of hFGCs regardless of the media used (3.3% of total cells in Zhou-medium and 4.8% of total cells in Shinohara-medium). We provide evidence that not only the choices of culture medium but also choices of the adequate substrate are crucial for optimizing culture protocols for male hFGCs. Optimizing culture conditions in order to improve the expansion of hFGCs will benefit the development of gametogenesis assays in vitro.

In vitro propagation and cardiac differentiation of canine induced pluripotent stem cells on carbon nanotube substrates

Induced pluripotent stem cells (iPSCs) have attracted an interest for personalized cell based therapy along with various other applications. There have been few studies that effective nanomaterial based scaffolds act as alternative to the commonly used feeder dependent in vitro maintenance of iPSCs. The present study provides the fundamental information on ex vivo behavior of canine iPSC (ciPSCs) maintained on carboxylic acid (COOH) functionalized single-walled carbon nanotubes (COOH-SWCNTs) and multi-walled carbon nanotubes (COOH-MWCNTs) substrates. Here in we evaluated the comparative colony morphology, propagation, characterization, cytocompatibility and differentiation capability of ciPSC cultured on MEF feeder taken as control, and COOH-SWCNTs and COOH-MWCNTs substrates. We observed a healthy growth of ciPSCs on both the types of carbon nanotubes (CNTs) similar to feeder. The ciPSC colonies grown on both CNTs were positive for alkaline phosphatase staining and expressed pluripotent markers with notable significance. Further, the ciPSC colonies grew on these CNTs retained the in vitro differentiation ability into three germ layers as well as cardiac cell. Cytotoxicity analysis revealed that (COOH) functionalized CNTs provided a culture condition of low cytotoxicity. The results of the present study indicated that (COOH) functionalized CNTs could be used as xeno-free substrate to support the maintenance of iPSCs.

Post-Passage rock inhibition induces cytoskeletal aberrations and apoptosis in Human embryonic stem cells

Human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs) are prone to anoikis after single cell dissociation. The small molecule, Y-27632 is known to increase survival of hESCs and hiPSCs by inhibiting the Rho-associated protein kinase (ROCK). However, the underlying mechanisms are still unclear. Here, we thoroughly screened small molecules to investigate the adhesion and survival of hESCs in adherent culture. Y-27632 provided higher adhesion and survival of hESCs by increased cell migration and preventing cell blebbing in single dissociated cells. The combination of Matrigel with poly-d-lysine increased the attachment and survival of dissociated cells via actin filament and microtubule spreading in Y-27632-treated cells. Although Y-27632 prevented apoptosis by suppressing actin filament contraction, microtubule bundling, and blebbing, prolonged Y-27632 treatment presented a different morphology in the attached growing hESC colony. It induced apoptosis of cells by promoting cytoplasmic spread, E-cadherin structural change, and increased detachment. It also induced actin cytoskeleton disruption, combined with microtubule and intermediate filament elongation. For optimal hPSC culture, our research suggests that Y-27632 should be removed shortly after passaging.

Feeder-free and xeno-free culture of human pluripotent stem cells using UCBS matrix

The ideal medium for human pluripotent stem cells (hPSCs) culture should be feeder-free, xeno-free, and completely defined. The present study aims to establish a new feeder-free and xeno-free system for culturing hPSCs. The system consists of the matrix, which was prepared from human umbilical cord blood serum (UCBS) and used to coat the culture plates, and the xeno-free medium, which was conventional serum-free hES medium supplemented with high concentrations of bFGF and Fibronectin. Compared with matrigel and mouse embryonic fibroblasts (MEFs), the UCBS matrix was proved to be equally suitable for the growth of hPSCs. After a series of experiments with different media and cytokins, the UCBS matrix was found worked the best with the basic medium (BM) supplemented with 20 ng/mL bFGF, 10 ug/mL fibronectin and Y-27632 for culture of hES cells. The hPSCs maintained normal karyotype, high proliferation rate and self-renewal ability after continuous culture more than 10 passages in this feeder-free and xeno-free system. Furthermore, a new human embryonic stem (hES) cell line was derived from discarded day 3 embryos in this newly developed culture system. In conclusion, this feeder-free and xeno-free system could not only be used to the culture hPSCs, but could also be used to derive new hES cell lines.

Chemically fixed autologous feeder cell-derived niche for human induced pluripotent stem cell culture

A newer method of hiPS culture on feeder cell-derived niche is reported in this study.

Effective Rho-associated protein kinase inhibitor treatment to dissociate human iPS cells for suspension culture to form embryoid body-like cell aggregates

Treatment conditions using Y-27632 in the preparation of cell suspension of dissociated human pluripotent stem cells (hiPSCs) were investigated in the context of embryoid body (EB)-like cell aggregates. The effectiveness of a pretreatment with Y-27632 before cell dissociation and that of a Y-27632 treatment during cell dissociation were investigated from the viewpoint of simplicity and robustness. The duration of Y-27632 treatment in the preparation process affected the circularity and agglomeration of dissociated hiPSCs. A single application of pretreatment failed to prevent the onset of blebbing. However, a pretreatment promoted the agglomeration of dissociated hiPSCs when combined with the addition of Y-27632 to cell suspension. Our results indicate that pretreatment enhances the agglomeration potential of dissociated hiPSCs. When cell dissociation was performed in the presence of Y-27632, dissociated hiPSCs possessed the highest circularity and significant agglomerating property. It was shown that treatment with Y-27632 during cell dissociation is a simple and robust method to prepare dissociated hiPSCs for suspension culture to form EB-like cell aggregates.

Low-molecular-weight inhibitors of cell differentiation enable efficient growth of mouse iPS cells under feeder-free conditions

Embryonic stem cells and induced pluripotent stem (iPS) cells are usually maintained on feeder cells derived from mouse embryonic fibroblasts (MEFs). In recent years, the cell culture of iPS cells under serum- and feeder-free conditions is gaining attention in overcoming the biosafety issues for clinical applications. In this study, we report on the use of multiple small-molecular inhibitors (i.e., CHIR99021, PD0325901, and Thiazovivin) to efficiently cultivate mouse iPS cells without feeder cells in a chemically-defined and serum-free condition. In this condition, we showed that mouse iPS cells are expressing the Nanog, Oct3/4, and SSEA-1 pluripotent markers, indicating that the culture condition is optimized to maintain the pluripotent status of iPS cells. Without these small-molecular inhibitors, mouse iPS cells required the adaptation period to start the stable cell proliferation. The application of these inhibitors enabled us the shortcut culture method for the cellular adaptation. This study will be useful to efficiently establish mouse iPS cell lines without MEF-derived feeder cells.

The self-renewal of mouse embryonic stem cells is regulated by cell-substratum adhesion and cell spreading

Mouse embryonic stem cells (mESCs) undergo self-renewal in the presence of the cytokine, leukaemia inhibitory factor (LIF). Following LIF withdrawal, mESCs differentiate, and this is accompanied by an increase in cell-substratum adhesion and cell spreading. The purpose of this study was to investigate the relationship between cell spreading and mESC differentiation. Using E14 and R1 mESC lines, we have restricted cell spreading in the absence of LIF by either culturing mESCs on chemically defined, weakly adhesive biomaterial substrates, or by manipulating the cytoskeleton. We demonstrate that by restricting the degree of spreading by either method, mESCs can be maintained in an undifferentiated and pluripotent state. Under these conditions, self-renewal occurs without the need for LIF and is independent of nuclear translocation of tyrosine-phosphorylated STAT3 or β-catenin, which have previously been implicated in self-renewal. We also demonstrate that the effect of restricted cell spreading on mESC self-renewal is not mediated by increased intercellular adhesion, as evidenced by the observations that inhibition of mESC adhesion using a function blocking anti E-cadherin antibody or siRNA do not promote differentiation. These results show that mESC spreading and differentiation are regulated both by LIF and by cell-substratum adhesion, consistent with the hypothesis that cell spreading is the common intermediate step in the regulation of mESC differentiation by either LIF or cell-substratum adhesion.

Feeder-free generation and long-term culture of human induced pluripotent stem cells using pericellular matrix of decidua derived mesenchymal cells

Human ES cells (hESCs) and human induced pluripotent stem cells (hiPSCs) are usually generated and maintained on living feeder cells like mouse embryonic fibroblasts or on a cell-free substrate like Matrigel. For clinical applications, a quality-controlled, xenobiotic-free culture system is required to minimize risks from contaminating animal-derived pathogens and immunogens. We previously reported that the pericellular matrix of decidua-derived mesenchymal cells (PCM-DM) is an ideal human-derived substrate on which to maintain hiPSCs/hESCs. In this study, we examined whether PCM-DM could be used for the generation and long-term stable maintenance of hiPSCs. Decidua-derived mesenchymal cells (DMCs) were reprogrammed by the retroviral transduction of four factors (OCT4, SOX2, KLF4, c-MYC) and cultured on PCM-DM. The established hiPSC clones expressed alkaline phosphatase, hESC-specific genes and cell-surface markers, and differentiated into three germ layers in vitro and in vivo. At over 20 passages, the hiPSCs cultured on PCM-DM held the same cellular properties with genome integrity as those at early passages. Global gene expression analysis showed that the GDF3, FGF4, UTF1, and XIST expression levels varied during culture, and GATA6 was highly expressed under our culture conditions; however, these gene expressions did not affect the cells’ pluripotency. PCM-DM can be conveniently prepared from DMCs, which have a high proliferative potential. Our findings indicate that PCM-DM is a versatile and practical human-derived substrate that can be used for the feeder-cell-free generation and long-term stable maintenance of hiPSCs.

Application of Rho-associated protein kinase (ROCK) inhibitor to human pluripotent stem cells

Susceptibility of human pluripotent stem cells (hPSCs), such as human iPS and embryonic stem (ES) cells, to single-cell dissociation has been a large obstacle to develop the efficient manipulation techniques required for stem cell research. When hPSCs are completely dissociated into single cells, programmed cell death (apoptosis) is immediately induced. A specific inhibitor of Rho-associated protein kinase (ROCK inhibitor), Y-27632, is of particular interest as a useful reagent that allows hPSCs to escape the dissociation-induced apoptosis. ROCK inhibitor has been used in a variety of applications associated with cell dissociation in the process of stem cell research, such as passaging, expansion, cryopreservation, gene transfer, differentiation induction, and cell sorting, suggesting that it may be a crucial reagent for the handling of hPSCs. This article reviews the current applications of ROCK inhibitors to stem cell research from the viewpoint of quality control of hPSCs.

Establishment of clinically compliant human embryonic stem cells in an autologous feeder-free system

Applications of human embryonic stem cells (hESCs) are limited by the use of mouse embryonic fibroblasts feeder and animal-derived components during culture. In this study, we demonstrated the potential use of extracellular matrix (ECM) derived from the autologous feeders to support long-term undifferentiated growth of hESCs in xeno-free, serum-free, and feeder-free conditions. Autologous H9 ebF (feeder cells derived from outgrowth of embryoid body [EB] predifferentiated from H9 hESCs) was derived from EBs predifferentiated from H9 hESCs through a direct-plating outgrowth system. The ECM comprising collagen VI, laminin, and fibronectin was extracted from H9 ebF through a freeze-thaw procedure. The autologous ECM together with animal component-free TeSR™2 medium was used to support long-term growth of H1 and H9 hESC lines for up to 20 passages. The maintenance of hESC undifferentiated state by autologous ECM was confirmed by the positive staining of hESC-specific markers (Oct4, SSEA-4, and Tra-1-60) and the expression of pluripotency marker genes (Oct4, Nanog, and Sox2). Flow cytometry further showed that more than 99% of hESCs retained the expression of SSEA-3/4 after long-term culture on autologous ECM. Pluripotency of hESCs on ECM was further proven by in vitro EB formation and in vivo teratoma assay. Overall, this study suggested a strategy for efficient propagation of clinically compliant hESCs in an autologous feeder-free culture system.

Lonely death dance of human pluripotent stem cells: ROCKing between metastable cell states

Two kinds of human pluripotent cells, human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs), promise new avenues for medical innovation. These human cells share many similarities with mouse counterparts, including pluripotency, and they exhibit several unique properties. This review examines the diversity of mammalian pluripotent cells from a perspective of metastable pluripotency states. An intriguing phenomenon unique to human pluripotent stem cells is dissociation-induced apoptosis, which has been a technical problem for various cellular manipulations. The discovery that this apoptosis is suppressed by ROCK inhibitors brought revolutionary change to this troublesome situation. We discuss possible links of the metastable pluripotent state to ROCK-dependent human embryonic stem cell apoptosis and summarize recent progress in molecular understandings of this phenomenon.