siRNA / miRNA gene silencing Human Primary Human Aortic Endothelial Cells GLO-1

Stem cells have the unique ability to self-renew or differentiate themselves into various cell types in response to appropriate signals. These cells are especially important for tissue repair, regeneration, replacement, or in the case of hematopoietic stem cells (HSCs) to differentiate into various myeloid populations. Appropriate signals refer to the growth factor supplements or cytokines that mediate differentiation of various stem cells into the required differentiated form. For instance, HSCs can be differentiated into dendritic cells (with IL-4 and GM-CSF), macrophages (with m-CSF) and MDSCs (with IL-6 and GM-CSF). Human pluripotent stem cells (hPSCs) and induced pluripotent stem cells (iPSCs) can be first cultured in neural differentiation media (GSK3𝛃-i, TGF𝛃-i, AMPK-i, hLIF) to form neural rosettes, which can be differentiated into neural or glial progenitors (finally differentiated into oligodendrocytes). Neural progenitors can be finally differentiated into glutaminergic (dibytyryl cAMP, ascorbic acid) and dopaminergic (SHH, FGF-8, BDNF, GDNF, TGF-𝛃3) neurons. Thus, it is important to first identify the self-renewing cell line: its source and its final differentiation state, followed by the supplements and cytokines required for the differentiation, and final use. Timelines are another thing that is considered. For instance, it takes 7-10 days to form neural rosettes from iPSCs and 3 days to differentiate neural progenitors to neurons. Finally, the stability for stem cell culture media varies. It is advised to make fresh media every time when differentiating HSCs to myeloid populations, whereas neural differentiation media may remain stable for two weeks when stored in dark between 2-8C.

ROS has a very short half-lives in biological environment as they are influenced by exposure to ambient oxygen. As it is highly reactive and hard to measure care should be taken to ensure the stability of the sample during isolation, preparation, storage, and analysis.

Get tips on using EGMTM -2 MV Microvascular Endothelial Cell Growth Medium-2 BulletKitTM to perform Stem cell culture media hPericytes

Get tips on using MicroRNA isolation kit to perform siRNA / miRNA gene silencing Rat - IEC-6 HuR

Transfection is a powerful technique that enables the study of the function of genes and gene products in cells. Based on the nature of experiments, we may need a stable DNA transfection in cells for persistent gain-of-function or loss-of-function of the target gene. For stable transfection, integration of a DNA vector into the chromosome is crucial which requires selective screening and clonal isolation. By carefully selecting a viral delivery system and related reagents we can ensure safe and highly-efficient delivery of expression constructs for high-level constitutive or inducible expression in any mammalian cell type.

Protein expression refers to the techniques in which a protein of interest is synthesized, modified or regulated in cells. The blueprints for proteins are stored in DNA which is then transcribed to produce messenger RNA (mRNA). mRNA is then translated into protein. In prokaryotes, this process of mRNA translation occurs simultaneously with mRNA transcription. In eukaryotes, these two processes occur at separate times and in separate cellular regions (transcription in nucleus and translation in the cytoplasm). Recombinant protein expression utilizes cellular machinery to generate proteins, instead of chemical synthesis of proteins as it is very complex. Proteins produced from such DNA templates are called recombinant proteins and DNA templates are simple to construct. Recombinant protein expression involves transfecting cells with a DNA vector that contains the template. The cultured cells can then transcribe and translate the desired protein. The cells can be lysed to extract the expressed protein for subsequent purification. Both prokaryotic and eukaryotic protein expression systems are widely used. The selection of the system depends on the type of protein, the requirements for functional activity and the desired yield. These expression systems include mammalian, insect, yeast, bacterial, algal and cell-free. Each of these has pros and cons. Mammalian expression systems can be used for transient or stable expression, with ultra high-yield protein expression. However, high yields are only possible in suspension cultures and more demanding culture conditions. Insect cultures are the same as mammalian, except that they can be used as both static and suspension cultures. These cultures also have demanding culture conditions and may also be time-consuming. Yeast cultures can produce eukaryotic proteins and are scalable, with minimum culture requirements. Yeast cultures may require growth culture optimization. Bacterial cultures are simple, scalable and low cost, but these may require protein-specific optimization and are not suitable for all mammalian proteins. Algal cultures are optimized for robust selection and expression, but these are less developed than other host platforms. Cell-free systems are open, free of any unnatural compounds, fast and simple. This system is, however, not optimal for scaling up.

Reporter gene assays are designed to test the regulation of the expression of a gene of interest. This is usually done by linking the promoter of the gene of interest with a gene such as a firefly luciferase, which can be easily detected by addition of luciferin that leads to an enzymatic reaction to produce luminescence. The enzymatic reaction can be correlated to the expression of the gene of interest. Another luciferase gene that can be used is Renilla luciferase. For an appropriate luciferase assay: 1. the reporter should express uniformly in all cells, 2. specifically respond to effectors that the assay intends to monitor, 3. have low intrinsic stability to quickly reflect transcriptional dynamics. It is important to have an equal number of cells plated in each testing condition to avoid any incorrect readouts. Reporter assays could be single or dual reporter assays. The reporter could be both luciferases. Most dual-luciferase assays involve adding two reagents to each sample and measuring luminescence following each addition. Adding the first reagent activates the first luciferase reporter reaction; adding the second reagent extinguishes first luciferase reporter activity and initiates the second luciferase reaction. Dual-luciferase assays have some advantages, including 1. reduces variability, 2. reduces background, 3. normalizes differences in transfection efficiencies between samples.

Get tips on using pMIR-REPORT™ miRNA Expression Reporter Vector System to perform Reporter gene assay luciferase - HEK 293 human embryonic kidney cells

Human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) have been greatly used for studies on embryonic development and cell differentiation.iPSCs provide a stable source for either self-renewal or differentiation into suitable cells when cultured in a particular environment. Pluripotent cell culture was originally started by deriving cells from inner cell mass (ICM) from pre-implanted blastocysts, these were called embryonic stem cells. These cells after isolation can be grown on traditional extracellular matrices (like mouse embryonic fibroblasts, MEFs) or feeder-free culture systems. DMEM/F12 has been the most commonly used basal media in the culture of pluripotent cells. These cells are cultured at normal atmospheric oxygen levels, 21%, however, some studies have proposed that 4% oxygen tension may be better for hESC growth. Higher D-glucose concentration (4.2g/l) and osmolarity (320mOsm) that mimics the natural environment of embryonic tissue are optimal for the growth of hESCs. Supplements like N2 and/or B-27, in the presence of growth factors like bFGF, have been shown to increase pluripotency of these cells. bFGF, FGF2 and other ligands of receptor tyrosine kinases like IGF are also required or maintain self-renewal ability of these cells. TGF𝛃1, by its activation of SMAD2/3 signalling, also represses differentiation of iPSCs. Other compounds like ROCK inhibitors reduce blebbing and apoptosis in these cells to maintain their clonogenicity. However, an inhibitor for LIF (leukaemia inhibitory factor, which is one of the pluripotent genes) has an opposing effect. Therefore, it is important to understand the culture conditions and media composition that affect downstream signalling in hESCs or iPSCs that may lead to their differentiation.