Abstract: Pluripotent stem cells can be induced from different cell types through transduction of the transcription factors by lentiviral, polycistronic vectors and other vectors. Most of these methods of generation of induced Pluripotent Stem (iPS) cells still use Mouse Embryonic Fibroblasts (MEF) as feeder layers. The use of animal feeder layers will hinder the clinical application of iPS cells because of the presence of unknown animal products, xenobiotics and when screening the intermediates iPS to study the mechanisms of cellular reprogramming, the feeder cells would be mixed in intermediates iPS cells samples. Here researchers generated iPS cells from MEF use only three factors Oct4, Klf4 and Sox2. Through add Vitamin C and gradually replaced the medium after retroviral infection, researchers promote the efficiency of induced iPS to 0.2%.