IPSC (Induced Pluripotent Stem Cell)

Adult cells from the body (maybe from skin, liver, stomach, blood, etc.) are taken and reprogrammed into pluripotent nature in which they can give rise to any particular cell lineage. These cells can be of major use in cancer therapies, research, development, etc. These IPSC cells behave just like embryonic stem cells in terms of gene expression, differentiation, and growth factor secretion. The cells are not differentiated and can be maintained in these stages with the introduction of transcription factors such as OCT3/4, SOX2, KLF4, and c-myc. 

Junying Yu et al prepared Induced Pluripotent Stem Cell lines by isolating trans-acting factors from mammalian oocytes and transferring them to somatic cells for reprogramming into an undifferentiated state. It was seen that four transcription factors (OCT4, SOX2, NANOG, and LIN28) are sufficient to maintain induced Pluripotent Stem (iPS) cells in culture conditions. These cells are further used to differentiate cells into all three germ layers. Besides these factors which are sufficient to reprogram human somatic cells, c-myc causes differentiation, and death of human ES cells. 

It was further analyzed that OCT4 knock-in mouse for ES cell line has an advantage in seeing geneticin resistant colonies (control used for selection and identification of transformed stem cells). Removal of OCT4 or SOX2 genes results in no appearance of reprogrammed colonies. NANOG helped in the recovery of reprogrammed cell lines while it was not helpful in the initiation of transformation for reprogramming into undifferentiated cells. But it helped in increasing 200 fold colony appearance whereas LIN28 has a very moderate effect on cells that are transformed to undifferentiated cells. So for initiation of SOX2, OCT4 is most required.

Later combined effects of the transcription factor were checked on IMR90 fetal fibroblast (available in ATCC) which are slow-growing in comparison to transformed undifferentiated iPS cells. This feature gives an advantage to the growth and selection of these iPS. All transcription factors expressed in the human ES cell line gave a total of 196 colonies of iPS whereas control showed no such colonies. Out of which, 35 colonies were selected for re-culturing for the next 3 weeks. Further, 4 most undifferentiated iPS colonies were selected for continuous culture for other research and development use or disease therapy e.g. sickle cell anemia, cancer, etc. 

Application – “Treatment of Sickle Cell Anaemia Mouse Model with iPS cells generated from Autologous Skin” by Jacob Hanna et al. 

Reference – 

Junying Yu et al. Induced pluripotent stem cell lines derived from human somatic cells. “Science” (20 Nov, 2007)

 

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