CRISPR Mouse Deletion ES (embryonic stem) 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.

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.

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.

The RNA-guided CRISPR-Cas9 nuclease system has revolutionized the genome editing practices. For the most part, the Cas9-mediated genome editing is performed either via nonhomologous end joining (NHEJ) or homology-directed repair (HDR) in mammalian cells, However, designing of specific sgRNAs and minimizing off-target cleavage mediated mutagenesis are the major challenges in CRISPR-Cas based genome editing. To circumvent these issues, we can take advantages of many available tools and approaches for sgRNA construction and delivery.

The RNA-guided CRISPR-Cas9 nuclease system has revolutionized the genome editing practices. For the most part, the Cas9-mediated genome editing is performed either via nonhomologous end joining (NHEJ) or homology-directed repair (HDR) in mammalian cells, However, designing of specific sgRNAs and minimizing off-target cleavage mediated mutagenesis are the major challenges in CRISPR-Cas based genome editing. To circumvent these issues, we can take advantages of many available tools and approaches for sgRNA construction and delivery.

TUNEL assay is the cell death detection method where the biochemical marker of apoptosis is DNA fragmentation. The assay involves the microscopical detection of generated DNA fragments with free 3'-hydroxyl residues. in apoptotic cells using enzyme terminal deoxynucleotidyl transferase (TdT) which adds biotinylated nucleotides at the site of DNA breaks. Major challenges of this method involve proper access of the enzyme which could be hampered by poor permeabilization and/or excessive fixation with cross-linking fixative (common with archival tissue). This issue can be resolved by optimizing the incubation time with Proteinase K or CytoninTM.

The RNA-guided CRISPR-Cas9 nuclease system has revolutionized the genome editing practices. For the most part, the Cas9-mediated genome editing is performed either via nonhomologous end joining (NHEJ) or homology-directed repair (HDR) in mammalian cells, However, designing of specific sgRNAs and minimizing off-target cleavage mediated mutagenesis are the major challenges in CRISPR-Cas based genome editing. To circumvent these issues, we can take advantages of many available tools and approaches for sgRNA construction and delivery.

The RNA-guided CRISPR-Cas9 nuclease system has revolutionized the genome editing practices. For the most part, the Cas9-mediated genome editing is performed either via nonhomologous end joining (NHEJ) or homology-directed repair (HDR) in mammalian cells, However, designing of specific sgRNAs and minimizing off-target cleavage mediated mutagenesis are the major challenges in CRISPR-Cas based genome editing. To circumvent these issues, we can take advantages of many available tools and approaches for sgRNA construction and delivery.

The RNA-guided CRISPR-Cas9 nuclease system has revolutionized the genome editing practices. For the most part, the Cas9-mediated genome editing is performed either via nonhomologous end joining (NHEJ) or homology-directed repair (HDR) in mammalian cells, However, designing of specific sgRNAs and minimizing off-target cleavage mediated mutagenesis are the major challenges in CRISPR-Cas based genome editing. To circumvent these issues, we can take advantages of many available tools and approaches for sgRNA construction and delivery.

Reporter gene assays enable high sensitivity measurement of gene expression and cell signaling through the addition of bioluminescent genes into target cells. One of the major challenges is to make a specific construct that no responses other than those related to the signaling pathway of interest. This can be achieved by selecting a highly specific reporter constructs containing only defined responsive elements and a minimal promoter linked to reporter enzyme such as luciferase.