Microfluidic isolation of highly pure embryonic stem cells using feeder-separated co-culture system.
ABSTRACT: Engineered artificial tissues from stem cells show great potential in regenerative medicine, disease therapies and organ transplantation. To date, stem cells are typically co-cultured with inactivated feeder layers to maintain their undifferentiated state, and to ensure reliable cell purity. Herein, we propose a novel microfabricated approach for feeder-separated coculture of mouse embryonic stem (mES) cells on polydimethylsiloxane (PDMS) porous membrane-assembled 3D-microdevice. Normal mouse embryonic fibroblasts (mEFs) without inactivation were specifically co-cultured with mES cells, resulting in the formation of mES cell colonies on spatially controlled co-culture with feeder layers. An excellent undifferentiated state was confirmed by the expressions of Nanog, octamer binding protein 4 (Oct-4) and alkaline phosphatase (ALP) after 5 days culture. As a result, with the significant advantages of efficiency and simplicity, pure mES cell populations (a purity of 89.2%) from mEFs co-cultures were easily collected without any further purification or separation.
Project description:Successful realization of the enormous potential of pluripotent stem cells in regenerative medicine demands the development of well-defined culture conditions. Maintenance of embryonic stem cells (ESCs) typically requires co-culture with feeder layer cells, generally mouse embryonic fibroblasts (MEFs). Concerns about xenogeneic pathogen contamination and immune reaction to feeder cells underlie the need for ensuring the safety and efficacy of future stem cell-based products through the development of a controlled culture environment. To gain insight into the effectiveness of MEF layers, here we have developed a biomimetic synthetic feeder layer (BSFL) that is acellular and replicates the stiffness and topography of MEFs. The mechanical properties of MEFs were measured using atomic force microscopy. The average Young's modulus of the MEF monolayers was replicated using tunable polyacrylamide (PA) gels. BSFLs replicated topographical features of the MEFs, including cellular, subcellular, and cytoskeletal features. On BSFLs, mouse ESCs adhered and formed compact round colonies; similar to on MEF controls but not on Flat PA. ESCs on BSFLs maintained their pluripotency and self-renewal across passages, formed embryoid bodies and differentiated into progenitors of the three germ layers. This acellular biomimetic synthetic feeder layer supports stem cell culture without requiring co-culture of live xenogeneic feeder cells, and provides a versatile, tailorable platform for investigating stem cell growth.Embryonic stem cells have enormous potential to aid therapeutics, because they can renew themselves and become different cell types. This study addresses a key challenge for ESC use - growing them safely for human patients. ESCs typically grow with a feeder layer of mouse fibroblasts. Since patients have a risk of immune response to feeder layer cells, we have developed a material to mimic the feeder layer and eliminate this risk. We investigated the influence of feeder layer topography and stiffness on mouse ESCs. While the biomimetic synthetic feeder layer contains no live cells, it replicates the stiffness and topography of feeder layer cells. Significantly, ESCs grown on BSFLs retain their abilities to grow and become multiple cell types.
Project description:Human induced pluripotent stem cells (hiPSCs) are a type of pluripotent stem cells artificially derived from an adult somatic cell (typically human fibroblast) by forced expression of specific genes. In recent years, different feeders like inactivated mouse embryonic fibroblasts (MEFs), human dermal fibroblasts (HDFs), and feeder free system have commonly been used for supporting the culture of stem cells in undifferentiated state. In the present work, the culture of hiPSCs and their characterizations on BD Matrigel (feeder-and serum-free system), MEF and HDF feeders using cell culture methods and molecular techniques were evaluated and compared. The isolated HDFs from foreskin samples were reprogrammed to hiPSCs using gene delivery system. Then, the pluripotency ability of hiPSCs cultured on each layer was determined by teratoma formation and immunohistochemical staining. After EBs generation the expression level of three germ layers genes were evaluated by Q-real-time PCR. Also, the cytogenetic stability of hiPSCs cultured on each condition was analyzed by karyotyping and comet assay. Then, the presence of pluripotency antigens were confirmed by Immunocytochemistry (ICC) test and alkaline phosphatase staining. This study were showed culturing of hiPSCs on BD Matrigel, MEF and HDF feeders had normal morphology and could maintain in undifferentiated state for prolonged expansion. The hiPSCs cultured in each system had normal karyotype without any chromosomal abnormalities and the DNA lesions were not observed by comet assay. Moreover, up-regulation in three germ layers genes in cultured hiPSCs on each layer (same to ESCs) compare to normal HDFs were observed (p?<?0.05). The findings of the present work were showed in stem cells culturing especially hiPSCs both MEF and HDF feeders as well as feeder free system like Matrigel are proper despite benefits and disadvantages. Although, MEFs is suitable for supporting of stem cell culturing but it can animal pathogens transferring and inducing immune response. Furthermore, HDFs have homologous source with hiPSCs and can be used as feeder instead of MEF but in therapeutic approaches the cells contamination is a problem. So, this study were suggested feeder free culturing of hiPSCs on Matrigel in supplemented media (without using MEF conditioned medium) resolves these problems and could prepare easy applications of hiPSCs in therapeutic approaches of regenerative medicine such as stem-cell therapy and somatic cell nuclear in further researches.
Project description:The crosstalk between cells is important for differentiation of cells. Murine-derived feeder cells, SNL76/7 feeder cells (SNLs) or mouse primary embryonic fibroblast feeder cells (MEFs) are widely used for culturing undifferentiated human induced pluripotent stem cells (hiPSCs). It is still unclear whether different culture conditions affect the induction efficiency of definitive endoderm (DE) differentiation from hiPSCs. Here we show that the efficiency of DE differentiation from hiPSCs cultured on MEFs was higher than that of hiPSCs cultured on SNLs. The qPCR, immunofluorescent and flow cytometry analyses revealed that the expression levels of mRNA and/or proteins of the DE marker genes, SOX17, FOXA2 and CXCR4, in DE cells differentiated from hiPSCs cultured on MEFs were significantly higher than those cultured on SNLs. Comprehensive RNA sequencing and molecular network analyses showed the alteration of the gene expression and the signal transduction of hiPSCs cultured on SNLs and MEFs. Interestingly, the expression of non-coding hXIST exon 4 was up-regulated in hiPSCs cultured on MEFs, in comparison to that in hiPSCs cultured on SNLs. By qPCR analysis, the mRNA expression of undifferentiated stem cell markers KLF4, KLF5, OCT3/4, SOX2, NANOG, UTF1, and GRB7 were lower, while that of hXIST exon 4, LEFTY1, and LEFTY2 was higher in hiPSCs cultured on MEFs than in those cultured on SNLs. Taken together, our finding indicated that differences in murine-feeder cells used for maintenance of the undifferentiated state alter the expression of pluripotency-related genes in hiPSCs by the signaling pathways and affect DE differentiation from hiPSCs, suggesting that the feeder cells can potentiate hiPSCs for DE differentiation.
Project description:The biological activity of cell-derived substrates to maintain undifferentiated murine-induced pluripotent stem (iPS) cells was correlated to membrane fluidity as a new parameter of cell culture substrates. Murine embryonic fibroblasts (MEFs) were employed as feeder cells and their membrane fluidity was tuned by chemical fixation using formaldehyde (FA). Membrane fluidity was evaluated by real-time single-molecule observations of green fluorescent protein-labeled epidermal growth factor receptors on chemically fixed MEFs. Biological activity was monitored by colony formation of iPS cells. Treatment with a low concentration of FA sustained the membrane fluidity and biological activity, which were comparable to those of mitomycin C-treated MEFs. The biological activity was further confirmed by sustained expression of alkaline phosphatase, SSEA-1, and other pluripotency markers in iPS cells after 3-5 days of culture on FA-fixed MEFs. Chemical fixation of feeder cells has several advantages such as providing ready-to-use culture substrates without contamination by proliferating feeder cells. Therefore, our results provide an important basis for the development of chemically fixed culture substrates for pluripotent stem cell culture as an alternative to conventional treatment by mitomycin C or x-ray irradiation.
Project description:Culture conditions that support the growth of undifferentiated human embryonic stem cells (hESCs) have already been established using primary human amnion epithelial cells (hAECs) as an alternative to traditional mitotically inactivated mouse embryonic fibroblasts (MEFs). In the present work, inner cell masses (ICM) were isolated from frozen embryos obtained as donations from couples undergoing in vitro fertilization (IVF) treatment and four new hESC lines were derived using hAECs as feeder cells. This feeder system was able to support continuous growth of what were, according to their domed shape and markers, undifferentiated naïve-like hESCs. Their pluripotent potential were also demonstrated by embryoid bodies developing to the expected three germ layers in vitro and the productions of teratoma in vivo. The cell lines retained their karyotypic integrity for over 35 passages. Transmission electron microscopy (TEM) indicated that these newly derived hESCs consisted mostly of undifferentiated cells with large nuclei and scanty cytoplasm. The new hESCs cultured on hAECs showed distinct undifferentiated characteristics in comparison to hESCs of the same passage maintained on MEFs. This type of optimized culture system may provide a useful platform for establishing clinical-grade hESCs and assessing the undifferentiated potential of hESCs.
Project description:Various feeder layers have been extensively applied to support the prolonged growth of human pluripotent stem cells (hPSCs) for in vitro cultures. Among them, mouse embryonic fibroblast (MEF) and mouse fibroblast cell line (SNL) are most commonly used feeder cells for hPSCs culture. However, these feeder layers from animal usually cause immunogenic contaminations, which compromises the potential of hPSCs in clinical applications. In the present study, we tested human umbilical cord mesenchymal stem cells (hUC-MSCs) as a potent xeno-free feeder system for maintaining human induced pluripotent stem cells (hiPSCs). The hUC-MSCs showed characteristics of MSCs in xeno-free culture condition. On the mitomycin-treated hUC-MSCs feeder, hiPSCs maintained the features of undifferentiated human embryonic stem cells (hESCs), such as low efficiency of spontaneous differentiation, stable expression of stemness markers, maintenance of normal karyotypes, in vitro pluripotency and in vivo ability to form teratomas, even after a prolonged culture of more than 30 passages. Our study indicates that the xeno-free culture system may be a good candidate for growth and expansion of hiPSCs as the stepping stone for stem cell research to further develop better and safer stem cells.
Project description:Pluripotent stem cells (PSCs) are considered as being an important cell source for regenerative medicine. The culture of PSCs usually requires a feeder cell layer or cell adhesive matrix coating such as Matrigel, laminin, and gelatin. Although a feeder-free culture using a matrix coating has been popular, the on-feeder culture is still an effective method for the fundamental study of regenerative medicine and stem cell biology. To culture PSCs on feeder cell layers, the elimination of feeder cells is required for biological or gene analysis and for cell passage. Therefore, a simple and cost-effective cell sorting technology is required. There are several commercialized cell-sorting methods, such as FACS or MACS. However, these methods require cell labeling by fluorescent dye or magnetic antibodies with complicated processes. To resolve these problems, we focused on dielectrophoresis (DEP) phenomena for cell separation because these do not require any fluorescent or magnetic dyes or antibodies. DEP imposes an electric force on living cells under a non-uniform AC electric field. The direction and magnitude of the DEP force depend on the electric property and size of the cell. Therefore, DEP is considered as a promising approach for sorting PSCs from feeder cells. In this study, we developed a simple continuous cell-sorting device using the DEP force and fluid-induced shear force. As a result, mouse embryonic stem cells (mESCs) were purified from a mixed-cell suspension containing mESCs and mouse embryonic fibroblasts (MEFs) using our DEP cell-sorting device.
Project description:Preparation of mouse embryonic fibroblast (MEF) feeder cells to maintain pluripotent stem cells (PSCs) is time consuming and involved in animal issues. Here, we demonstrated a novel method to prepare feeder cells with high efficiency, timesaving, and low costs. MEFs in 3?×?104 cell/cm2 were fixed by methanol for 5?min and air drying for 5?min. Thereafter, the methanol fixed MEF cells (MT-MEF) were able to be used directly to culture PSCs or stored at room temperature for the future usage. PSCs cultured on MT-MEF could be continuously expanded for over 40 passages with the naïve pluripotency. MT-MEFs could also be used to maintain human and pig iPSCs. Moreover, methanol fixed MEFs' culture dish was able to be reused for at least 4 times, and to be applied for antibiotic resistant screening assay to establishing stable transfected PSC lines. Alternatively, the immortalized cell lines, for instance NIH3T3 cells, could also be fixed by methanol and used as feeder cells to maintain PSCs. Thus, this novel means of methanol fixed feeder cells can completely replace the mitomycin C and gamma radiation treated MEF feeder cells, and be used to maintain PSCs derived from mouse as well as other animal species.
Project description:Human amniotic epithelial cells (HAECs) are a unique embryonic cell source that potentially can be used as feeder layers for expanding different types of stem cells. In vivo, HAECs uniformly expressed pan-cytokeratins (pan-CK) and heterogeneously expressed vimentin (Vim). The two phenotypes expressing either pan-CK(+)/Vim(+) or pan-CK(+)/Vim(-) were maintained in serum-free media with high calcium. In contrast, all HAECs became pan-CK(+)/Vim(+) in serum-containing media, which also promoted HAEC proliferation for at least eight passages, especially supplemented with epidermal growth factor and insulin. Mitomycin C-arrested HAEC feeder layers were more effective in promoting clonal growth of human limbal epithelial progenitors than conventional 3T3 murine feeder layers. Cells in HAEC-supported clones were uniformly smaller, sustained more proliferation, and expressed less CK12 and connexin 43 but higher levels of stem cell-associated markers such as p63, Musashi-1, and ATP-binding cassette subfamily G2 than those of 3T3-supported clones. Subculturing of clonally expanded limbal progenitors from HAEC feeder layers, but not from 3T3 feeder layers, gave rise to uniformly p63-positive epithelial progenitor cells as well as nestin-positive neuronal-like progenitors. Collectively, these results indicated that HAECs can be used as a human feeder layer equivalent for more effective ex vivo expansion of adult epithelial stem cells from the human limbus. Disclosure of potential conflicts of interest is found at the end of this article.
Project description:BACKGROUND: For therapeutic usage of induced Pluripotent Stem (iPS) cells, to accomplish xeno-free culture is critical. Previous reports have shown that human embryonic stem (ES) cells can be maintained in feeder-free condition. However, absence of feeder cells can be a hostile environment for pluripotent cells and often results in karyotype abnormalities. Instead of animal feeders, human fibroblasts can be used as feeder cells of human ES cells. However, one still has to be concerned about the existence of unidentified pathogens, such as viruses and prions in these non-autologous feeders. METHODOLOGY/PRINCIPAL FINDINGS: This report demonstrates that human induced Pluripotent Stem (iPS) cells can be established and maintained on isogenic parental feeder cells. We tested four independent human skin fibroblasts for the potential to maintain self-renewal of iPS cells. All the fibroblasts tested, as well as their conditioned medium, were capable of maintaining the undifferentiated state and normal karyotypes of iPS cells. Furthermore, human iPS cells can be generated on isogenic parental fibroblasts as feeders. These iPS cells carried on proliferation over 19 passages with undifferentiated morphologies. They expressed undifferentiated pluripotent cell markers, and could differentiate into all three germ layers via embryoid body and teratoma formation. CONCLUSIONS/SIGNIFICANCE: These results suggest that autologous fibroblasts can be not only a source for iPS cells but also be feeder layers. Our results provide a possibility to solve the dilemma by using isogenic fibroblasts as feeder layers of iPS cells. This is an important step toward the establishment of clinical grade iPS cells.