Image of frozen, human induced pluripotent stem cells provided courtesy of Dr. Deepak Srivastava's lab.

Induced Pluripotent Stem Cells (iPSCs) are adult cells forced back into an embryonic cell-like state. This is typically done through genetic reprogramming. Mouse iPSCs were first made in 2006, while human iPSCs were not discovered until late 2007. Both human and mouse iPSCs expressed stem cell markers and demonstrated pluripotent characteristics, producing cells for all three germ layers. iPSCs are used in several applications, including drug development, disease modeling, and transplantation medicine. Currently, viruses are used to transfect non-pluripotent cells. Transfected genes are involved with pluripotency and include Oct 3/4, SOX-2, c-Myc, and Klf4. Cells are then typically selected for the expression of Nanog, a transcription factor associated with self renewal. While the use of viruses in this method must be confirmed to be safe for humans, this process provides a form of “devolution,” producing new uses for cells thought to be terminally differentiated.

 

References:

  1. Takahashi, K. and Yamanaka, S. 2006. Cell 126:663.
  2. Takahashi, K. et al. 2007. Cell 131:861.