In 2006, mouse fibroblasts were successfully transformed from a fully differentiated state to a state of pluripotency. These cells were designated induced pluripotent stem cells (iPSC).Since that news, human cells were successfully transformed and techniques to increase the safety and efficiency of production have been found. Other techniques have been developed which can correct genetic defects in iPSCs with the eventual goal of repairing or replacing defective tissues.
iPSCs still have issues to be resolved such as:
- certain methods of inducing pluripotency are tumorigenic
- iPSCs appear to have “memory” of their original cell type
- there is some data showing that iPSCs express certain proteins on their surface resulting in immune rejection even in cells donated from the host’s own tissue
- other complications such as efficiency (allowing sufficient numbers of cells to be generated within a clinically acceptable time at a clinically acceptable cost).
Some of these issues are already being addressed and quite frankly the pace of research has been astonishingly rapid. iPSCs are already being used to model disease and aid drug discovery. Due to the novelty of cell-based therapies and the fact that implanted cells are difficult or impossible to remove (unlike dosages of drugs which can be ceased in the event of adverse reaction), regulatory hurdles are necessarily high. However, as more trials are performed giving more data on safety these hurdles can be lowered somewhat and/or more easily surmounted. There are cell-based therapies already in or going through the regulatory process for trials using a variety of stem cell types. Not only do these prospective treatments face regulatory hurdles, they must also cross the Valley of Death of pharmaceutical research. Some researchers are finding ways of doing this on their own with intellectual property partnerships, and the NIH has been working to bridge the gap with new programs such as TRND.
This is a very exciting time for regenerative medicine.