From test-tube to human living : the transdifferentiation « recipe »
From stem cells in vitro to living being (worm or human), the molecular recipe of cell reprogramming and pluripotency seems to be conserved.
Proc Natl Acad Sci U S A April 9, 2012
April 9, 2012
Sophie Jarriault team has shown that molecular factors essentials to maintain pluripotency in vitro and used to induce cellular reprogramming are the same as those involved during the transdifferentiation in vivo. These results are published on April 9th 2012 in the Proceedings of the National Academy of Sciences of the United States of America.
Complex organisms are composed of differentiated cells (muscles, neurons, red blood cells, etc.). To produce new organs and bypass the need for a transplant, researchers are trying to find methods to produce these differentiated cells. Many methods are explored to generate replacement cells in vitro. for example, methodS that enables to dedifferentiate cells in induced pluripotent stem cells (iPS cells) and reprogram them afterwards have been explored, besides the controversial use of embryonic stem cells (ES cells). In recent years, another promising approach has been proposed that allowS differentiated cells to change their identity without going through a potentially tumorigenic pluripotent state: this is transdifferentiation. Working on this phenomenon, Sophie Jarriault team had already shown that it occurs naturally in the worm Caenorhabditis elegans, allowing a rectal cell to change in a motoneuron for instance. In their last study, researchers have focused on molecular aspects of the process. They have notably proved that direct reprogramming of a rectal cell needs a molecular cocktail of 4 factors. These factors are well known to play a key-role in vitro for ES cells pluripotency maintenance and iPS reprogramming. This is the first time that their role is shown in vivo in a pluricellular organism, and these factors could represent a conserved plasticity cassette.
Moreover, these results suggest that the recipe of forced processes obtained in laboratories is very close to the recipe of natural reprogramming mechanisms.