Dr. Yamanaka discovered that fully differentiated adult mouse and human cells can be reprogrammed to become undifferentiated, pluripotent cells by expressing only four transcription factors. He called these cells induced pluripotent cells (iPS cells).
Specifically, he showed that pluripotent stem cells can be generated from mouse embryonic fibroblasts and adult mouse tail tip fibroblasts by the retrovirus-mediated transfection of four transcription factors, Oct3/4, Sox2, c-Myc, and Klf4.
The iPS cells are indistinguishable from ES cells in morphology, proliferation, gene expression, and teratoma formation. When transplanted into blastocysts, mouse iPS cells derived from mouse embryonic fibroblasts can give rise to adult chimeras, which are competent for germline transmission.
These results are proof-of-principle that pluripotent stem cells can be generated from somatic cells by the combination of a small number of factors.
Dr. Yamanaka's research continues to explore the iPS technology. His laboratory is working to make the process more efficient and to discover ways to use it to improve our understanding of developmental biology and regenerative medicine.
Interviews with Deepak Srivastava, Shinya Yamanaka, and Robert Mahley on the focus and the impact of Dr. Yamanaka's discoveries
