Induction of Pluripotency by Defined Factors

Air date: Thursday, January 14, 2010, 3:00:00 PM
Time displayed is Eastern Time, Washington DC Local
Category: Wednesday Afternoon Lectures
Description: Human ES cells have been expected as suitable resources for cell transplantation therapies. However, it has sparked ethical controversy and causes immune rejection. Hence, we decided to generate an ideal pluripotent stem cell for innovative medicine.
At first, we constructed a pluripotency assay system that the candidate factors are introduced into neonate fibroblasts via retrovirus vectors. As the result, the set of Oct3/4, Sox2, c-Myc, and Klf-4 gave rise to drug resistant colonies implying potential pluripotency. The survived cells resembled ES cells in terms of morphology and proliferation showed ES cell markers and formed teratoma. It was named as induced pluripotent stem cell (iPS cell). iPS cells were created even from adult mouse fibroblasts. Moreover, iPS cells based on Nanog-expression demonstrated germline transmission. Furthermore, we successfully generated iPS cells from human adult fibroblasts, using a modified protocol.
However, tumor formation was observed in chimera mouse, probably due to c-Myc retrovirus integrated into genome. We re-modified the protocol and successfully established iPS cells without using c-Myc. As further effort to lower a risk of tumorigenesis, we recently succeeded in developing a virus-free method - using a pair of plasmid vectors, instead of retrovirus vectors, to introduce the four genes into mouse fibroblasts.
Further research results are discussed from the points of safety and induction efficiency of iPS cells for future clinical grade.
The NIH Director's Wednesday Afternoon Lecture Series includes weekly scientific talks by some of the top researchers in the biomedical sciences worldwide.
Runtime: 01:09:50
NLM Title: Induction of pluripotency by defined factors [electronic resource] / Shinya Yamanaka.
Series: NIH director's Wednesday afternoon lecture series
Author: Yamanaka, Shinya.
National Institutes of Health (U.S.)
Publisher: [Bethesda, Md. : National Institutes of Health, 2010]
Other Title(s): NIH director's Wednesday afternoon lecture series
Abstract: (CIT): Human ES cells have been expected as suitable resources for cell transplantation therapies. However, it has sparked ethical controversy and causes immune rejection. Hence, we decided to generate an ideal pluripotent stem cell for innovative medicine. At first, we constructed a pluripotency assay system that the candidate factors are introduced into neonate fibroblasts via retrovirus vectors. As the result, the set of Oct3/4, Sox2, c-Myc, and Klf-4 gave rise to drug resistant colonies implying potential pluripotency. The survived cells resembled ES cells in terms of morphology and proliferation showed ES cell markers and formed teratoma. It was named as induced pluripotent stem cell (iPS cell). iPS cells were created even from adult mouse fibroblasts. Moreover, iPS cells based on Nanog-expression demonstrated germline transmission. Furthermore, we successfully generated iPS cells from human adult fibroblasts, using a modified protocol. However, tumor formation was observed in chimera mouse, probably due to c-Myc retrovirus integrated into genome. We re-modified the protocol and successfully established iPS cells without using c-Myc. As further effort to lower a risk of tumorigenesis, we recently succeeded in developing a virus-free method - using a pair of plasmid vectors, instead of retrovirus vectors, to introduce the four genes into mouse fibroblasts. Further research results are discussed from the points of safety and induction efficiency of iPS cells for future clinical grade.
Subjects: Induced Pluripotent Stem Cells--physiology
Induced Pluripotent Stem Cells--transplantation

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