11/30/2023 0 Comments Stem tech stock![]() ![]() The lack of an abundant source of human lung epithelial cells is a major limitation for studying the lung disease phenotypes, drug screening and clinical application of these cells in respiratory disease. In addition, both MTeSR ™ and Essential 8 ™ Medium have been used to scale up production of iPSCs and have been shown to support iPSC growth for >50 passages without any signs of karyotypic abnormalities, along with maintaining the ability of iPSCs to differentiate into all three germ line lineages. ![]() Essential 8 ™ Medium has been extensively tested in multiple iPSC lines. Essential 8 ™ Medium is another xeno-free and feeder-free medium specially formulated for the growth and expansion of human pluripotent stem cells. It has been used to successfully maintain hundreds of ES cell and iPS cell lines and has supported the main pluripotency genes expression in ES and iPS cells. MTeSR ™ 1 is the most widely published feeder-free cell culture medium for ES and iPS cells, with established protocols for applications ranging from derivation to differentiation. To move toward feeder-free culture systems, researchers have also designed MTeSR ™ and Essential 8 ™ medium. These systems include Matrigel, or other extracellular matrix (ECM) proteins such as vitronectin, to maintain hESCs and hiPSCs and the reduction or complete removal of serum from human stem cell culture. More recently, researchers have developed feeder free systems for both hES and hiPS cell culture. The feeder cell preparation requires significant time and effort, is labor-intensive and hard to scale. Traditional human embryonic stem cells (hES cells) and induced pluripotent stem cells (hiPS cells) culture methods require the use of mouse or human fibroblast feeder layers. The following protocols provide a general guideline for the induction of iPSCs from fibroblasts using an inducible lentiviral system. These iPSC colonies can be isolated based on their morphology, expression of pluripotent genes and surface markers and can be expanded in an appropriate culture system to keep pluripotency over several passages. After introduction of reprogramming factors, cells begin to form colonies very similar to human embryonic stem cells. Recently, many advances have been made in improving the efficiency and the time it takes to derive iPSCs. It takes 1–2 weeks for mouse cells and 3–4 weeks for human cells and the efficiencies are as low as 0.01–0.1 %. iPSC generation is a slow and inefficient process. To generate the iPSCs, each of the pluripotency factors can be also replaced by related transcription factors, miRNAs or small molecules. The retroviral vectors require integration into host chromosomes to express reprogramming genes, but DNA-based vectors and plasmid vectors do not generally integrate to the cell genome. There are multiple methods to generate iPSCs, including retrovirus or lentivirus-mediated gene transduction and chemical induction. The original set of reprogramming factors (also called Yamanaka factors) are the genes Oct4 (Pou5f1), Sox2, cMyc, and Klf4. These cells show qualities very similar to human embryonic stem cells. Induced pluripotent stem cells (iPSCs) are typically derived by introducing a specific set of pluripotency-associated genes, or “reprogramming factors,” into an adult cell type. ![]()
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