Method to Isolate Embryonic Stem Cells Directed to Forebrain Interneuron Fate

GABAergic interneurons of the forebrain are critical for maintaining the balance of inhibition and excitation in these brain regions. They are attractive candidates for cell based therapies for epilepsy or other brain disorders due to over excitation including schizophrenia, because they have a remarkable ability to migrate extensively and survive after transplantation into postnatal cortex. To fulfill their therapeutic potential, a method for the isolation of these forebrain interneurons from embryonic stem-cell cultures is needed.

Cornell researchers developed a method to generate a limitless supply of interneurons from mammalian embryonic stem cells (ESCs) for preclinical or clinical studies. A marker protein, such as GFP, was introduced into mouse or human ESCs under the control of a cell fate-specific promoter. The modified ESCs will fluoresce when they have committed to an interneuron fate but remain plastic enough to synaptically integrate into the host milieu upon transplantation. Expression of GFP not only allows these particular cells to be identified and isolated by FACS, but also allows them to be tracked after transplantation. These mouse ESC-derived interneuron progenitors have been shown to behave very similarly to progenitors obtained from the developing mouse brain. They are able to migrate extensively and they express mature interneuron markers of the various subclasses of interneurons. Electrophysiological recordings also show that they have firing patterns very similar to those of mature interneurons. When injected into a chemically-induced mouse epileptic brain, these progenitors are able to migrate, survive, and differentiate into interneurons.

In summary, by providing a limitless supply of highly enriched and easily-obtained interneuron progenitors, this method will not only be important for the study of cortical interneuron development in the normal and disease states, but also provide a platform for cell-based therapies, especially where drug-based therapies have failed. This cell-based therapy can take advantage of either the intrinsic ability of these interneurons to develop into inhibitory neurons or their potential ability to serve as a vehicle for delivering anti-epileptic agents.