Project description:Culture conditions play an important role in regulating the genomic integrity of Human Pluripotent Stem Cells (HPSCs). We report that HPSCs cultured in Essential 8 (E8) and mTeSR, two widely used media for feeder-free culturing of HPSCs, had many fold higher levels of ROS and higher mitochondrial potential than cells cultured in Knockout Serum Replacement containing media (KSR). HPSCs also exhibited increased levels of 8-hydroxyguanosine, phospho-histone-H2a.X and p53, as well as increased sensitivity to γ-irradiation in these two media. HPSCs in E8 and mTeSR had increased incidence of changes in their DNA sequence, indicating genotoxic stress, in addition to changes in nucleolar morphology and number. Addition of antioxidants to E8 and mTeSR provided only partial rescue. Our results suggest that it is essential to determine cellular ROS levels in addition to currently used criteria i.e. pluripotency markers, differentiation into all three germ layers and normal karyotype through multiple passages, in designing culture media.
Project description:Human neural stem cells (hNSC) have the potential to provide novel cell-based therapies for neurodegenerative conditions such as multiple sclerosis and Parkinson's disease. In order to realise this goal, protocols need to be developed that allow for large quantities of hNSC to be cultured efficiently. As such, it is important to identify factors which enhance the growth of hNSC. In vivo, stem cells reside in distinct microenvironments or niches that are responsible for the maintenance of stem cell populations. A common feature of niches is the presence of the extracellular matrix molecule, laminin. Therefore, this study investigated the effect of exogenous laminin on hNSC growth.To measure hNSC growth, we established culture conditions using B27-supplemented medium that enable neurospheres to grow from human neural cells plated at clonal densities. Limiting dilution assays confirmed that neurospheres were derived from single cells at these densities. Laminin was found to increase hNSC numbers as measured by this neurosphere formation. The effect of laminin was to augment the proliferation/survival of the hNSC, rather than promoting the undifferentiated state. In agreement, apoptosis was reduced in dissociated neurospheres by laminin in an integrin beta1-dependent manner.The addition of laminin to the culture medium enhances the growth of hNSC, and may therefore aid their large-scale production.
Project description:Human pluripotent stem cells are considered to be ideal cell sources for regenerative medicine, but their clinical and industrial application is hindered by their tumorigenic potential. Previously we have identified a pluripotent stem cell-specific lectin rBC2LCN recognizing podocalyxin as a cell surface ligand. More recently, podocalyxin was found to be a soluble ligand of rBC2LCN that is secreted specifically from human pluripotent stem cells into cell culture media. Taking advantage of this phenomenon, we have previously developed a sandwich assay targeting the soluble podocalyxin using rBC2LCN as a capturing probe and another lectin rABA as an overlay probe to detect human pluripotent stem cells residing in cell therapy products derived from human pluripotent stem cells. A drawback to this, however, was that cell culture media containing fetal bovine serum was found to cause a substantial background signal to the sandwich assay. To reduce the background and increase the sensitivity, we screened different overlay probes to detect the soluble podocalyxin. Among them, an anti-keratan sulfate monoclonal antibody called R-10G showed the highest sensitivity and provided a low background signal to fetal bovine serum. The established sandwich assay using rBC2LCN and R-10G was proved to be powerful, which allowed the high-sensitive detection of human induced pluripotent stem cells residing among clinical-grade cardiomyocytes and neural stem cells, both derived from human induced pluripotent stem cells. The developed method has a possibility to be a standard technology to detect human induced pluripotent stem cells resided in various types of cell therapy products.
Project description:We have used single cell transcriptome analysis to re-examine the substates of early passage, karyotypically Normal, and late passage, karyotypically Abnormal ('Culture Adapted') human embryonic stem cells characterized by differential expression of the cell surface marker antigen, SSEA3. The results confirmed that culture adaptation is associated with alterations to the dynamics of the SSEA3(+) and SSEA3(-) substates of these cells, with SSEA3(-) Adapted cells remaining within the stem cell compartment whereas the SSEA3(-) Normal cells appear to have differentiated. However, the single cell data reveal that these substates are characterized by further heterogeneity that changes on culture adaptation. Notably the Adapted population includes cells with a transcriptome substate suggestive of a shift to a more naïve-like phenotype in contrast to the cells of the Normal population. Further, a subset of the Normal SSEA3(+) cells expresses genes typical of endoderm differentiation, despite also expressing the undifferentiated stem cell genes, POU5F1 (OCT4) and NANOG, whereas such apparently lineage-primed cells are absent from the Adapted population. These results suggest that the selective growth advantage gained by genetically variant, culture adapted human embryonic stem cells may derive in part from a changed substate structure that influences their propensity for differentiation.
Project description:The generation of vasculature is one of the most important challenges in tissue engineering and regeneration. Human dental pulp stem cells (hDPSCs) are some of the most promising stem cell types to induce vasculogenesis and angiogenesis as they not only secrete vascular endothelial growth factor (VEGF) but can also differentiate in vitro into both endotheliocytes and pericytes in serum-free culture media. Moreover, hDPSCs can generate complete blood vessels containing both endothelial and mural layers in vivo, upon transplantation into the adult brain. However, many of the serum free media employed for the growth of hDPSCs contain supplements of an undisclosed composition. This generates uncertainty as to which of its precise components are necessary and which are dispensable for the vascular differentiation of hDPSCs, and also hinders the transfer of basic research findings to clinical cell therapy. In this work, we designed and tested new endothelial differentiation media with a fully defined composition using standard basal culture media supplemented with a mixture of B27, heparin and growth factors, including VEGF-A165 at different concentrations. We also optimized an in vitro Matrigel assay to characterize both the ability of hDPSCs to differentiate to vascular cells and their capacity to generate vascular tubules in 3D cultures. The description of a fully defined serum-free culture medium for the induction of vasculogenesis using human adult stem cells highlights its potential as a relevant innovation for tissue engineering applications. In conclusion, we achieved efficient vasculogenesis starting from hDPSCs using serum-free culture media with a fully defined composition, which is applicable for human cell therapy purposes.
Project description:Exposure to lead (Pb) during childhood can result in learning disabilities and behavioral problems. Although described in animal models, whether Pb exposure also alters neuronal differentiation in the developing brains of exposed children is unknown. Here, we investigated the effects of physiologically relevant concentrations of Pb (from 0.4 to 1.9?M) on the capacity of human embryonic stem cells (hESCs) to progress to a neuronal fate. We found that neither acute nor chronic exposure to Pb prevented hESCs from generating neural progenitor cells (NPCs). NPCs derived from hESCs chronically exposed to 1.9?M Pb throughout the neural differentiation process generated 2.5 times more TUJ1-positive neurons than those derived from control hESCs. Pb exposure of hESCs during the stage of neural rosette formation resulted in a significant decrease in the expression levels of the neural marker genes PAX6 and MSI1. Furthermore, the resulting NPCs differentiated into neurons with shorter neurites and less branching than control neurons, as assessed by Sholl analysis. DNA methylation studies of control, acutely treated hESCs and NPCs derived from chronically exposed hESCs using the Illumina HumanMethylation450 BeadChip demonstrated that Pb exposure induced changes in the methylation status of genes involved in neurogenetic signaling pathways. In summary, our study shows that exposure to Pb subtly alters the neuronal differentiation of exposed hESCs and that these changes could be partly mediated by modifications in the DNA methylation status of genes crucial to brain development.
Project description:Hyaluronan (HA), a major component of the extracellular matrix, plays a key role in cell proliferation, growth, survival, polarization and differentiation. We investigated the optimization of a HA hydrogel scaffold for culture of human oral mucosal epithelial cells (OMECs) for potential application in limbal stem cell therapy. The effect of the optimized scaffold on OMEC cell sheet morphology, cell metabolic activity and expression of genes associated with stemness, adherence and cell damage was studied. The results indicate that HA hydrogels crosslinked with polyethylene glycol diacrylate (PEGDA) failed to support OMEC attachment and growth. However, HA hydrogel scaffolds dried for three days and coated with 1 mg/mL collagen IV produced a full OMEC sheet. Cell morphology was comparable to control after three weeks culture, maintaining 76% metabolic activity. Of apoptosis-related genes, the pro-apoptotic markers CASP3 and BAX2 were upregulated and downregulated, respectively, compared to control whereas the anti-apoptotic marker BCL2 was downregulated. The expression level of stemness genes ΔNp63α and ABCG2 was significantly higher than control. Genes associated with improved scar-less wound healing (integrin-V) and protection of the ocular surface (cadherin-1) had ~3-fold increased expression. These data suggest that our optimized HA-hydrogel scaffold could enhance culture of OMEC cell sheets for use in ocular reconstruction.
Project description:This Letter examines the physical and chemical changes that occur at the interface of methyl-terminated alkanethiol self-assembled monolayers (SAMs) after exposure to cell culture media used to derive embryoid bodies (EBs) from pluripotent stem cells. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy analysis of the SAMs indicates that protein components within the EB cell culture medium preferentially adsorb at the hydrophobic interface. In addition, we examined the adsorption process using surface plasmon resonance and atomic force microscopy. These studies identify the formation of a porous, mat-like adsorbed protein film with an approximate thickness of 2.5 nm. Captive bubble contact angle analysis reveals a shift toward superhydrophilic wetting behavior at the cell culture interface due to adsorption of these proteins. These results show how EBs are able to remain in suspension when derived on hydrophobic materials, which carries implications for the rational design of suspension culture interfaces for lineage specific stem-cell differentiation.
Project description:Exposure to the ambient air pollutant ozone induces acute and chronic respiratory health effects in part by causing inflammation of the airways. Several aspects of the inflammatory response to ozone can be modeled in vitro using primary human bronchial epithelial cells (HBECs) cultured at an air-liquid interface. We tested two commonly used HBEC culture media systems, one proprietary and one non-proprietary, to identify which system yielded the most in vivo-like pro-inflammatory response to acute ozone exposure as indicated by gene expression. Cells from six donors were grown in each culture system in parallel followed by examination of epithelial morphology and cell type proportions prior to ozone exposure. Cultures grown in the proprietary system were notably thicker and contained more ciliated and secretory cells, as well as internal cyst-like structures. The transcriptomic response to acute ozone exposure (0.5 parts per million ozone x 2 hours) was strongly affected by media. HBECs grown in the proprietary system exhibited minimal changes after ozone, with only only 7 differentially expressed genes (DEGs). In contrast, HBECs grown in the non-proprietary system exhibited a more dynamic response with 128 DEGs, including hallmark response genes indicative of inflammation (CXCL8) and oxidative stress (HMOX1). Gene set enrichment analysis using the 128 DEGs further corroborated upregulation of oxidative stress and inflammation pathways. In total, our results indicate that the choice of HBEC culture media should be carefully considered to best model the in vivo response to ozone.