The pace of change in the induced pluripotent stem cell (iPS cell) field is nothing short of amazing.
Originally it was thought that introduction of four genetic factors (Oct4, Sox2, Klf4, and c-Myc) was needed to reprogram adult cells into embryonic stem cell equivalents. There have been some variations on that theme (like three genetic factors, different gene delivery methods, for example).
Then, Professor Schöler’s team at the Max Planck Institute in Germany demonstrated that Oct4 and Klf4 are sufficient to induce pluripotency in neural stem cells. Now the same team has been able to create iPS cells using only one genetic factor (Oct4).
The Max Planck team again used neural stem cells (NSCs) as the starting point. NSCs endogenously express Sox2, c-Myc and Klf4 — they are close enough to the pluripotent state that little tweaking is necessary.
It’s good news that it was possible to generate iPS cells without using oncogenic factors (Klf4 and c-Myc). However, it was still necessary to use a retrovirus to deliver the Oct4 gene and given grave concerns about the cancer-promoting properties of retroviruses that is clearly an obstacle for human clinical development.
Meanwhile, in the world of commerce, the Japanese stem cell community was recently shocked to learn that the German pharmaceutical company Bayer AG had filed a patent claiming the iPS method before Professor Shinya Yamanaka‘s group. This development will create added complexity in this space (and many happy lawyers).