We have been developing new tools for the genetic modification of embryonic stem cells (ESCs). Part of the potential for use of ESCs in treatments or as models of disease depends on the ability to change genes within ESCs. We have developed a novel system, which we call the Floxin system, that allows for the more efficient modification of genes within mouse ESCs than has been historically feasible. We have used this system to insert mutations that cause human diseases into mouse ESCs. Introducing human mutations into ESCs has allowed us to study the function of these mutations in the context of stem cell function and gain insight into how these mutations cause human disease.
We are interested in extending our findings by modeling an important class of neurological diseases that predominantly affect spinal motor neurons, the neurons that control muscle movement. The most well known of these motor neuronopathies is Amyotrophic Lateral Sclerosis (ALS), commonly referred to as Lou Gehrig’s disease, but there are a number of other motor neuronopathies including Hereditary Motor Neuronopathy and Spinal Muscular Atrophy.
Human genetic studies have identified many mutations that cause these diseases, but it is not understood why these mutations kill motor neurons. This lack of understanding about the root causes of motor neuron diseases currently hinders the development of effective treatments. We are currently using the Floxin system to introduce human motor neuronopathy-associated mutations into mouse ESCs. We have introduced mutations into two disease-associated genes, and are deriving motor neurons from these modified ESCs to study how the mutations kill these cells.
The development of cell-based models of human diseases is likely to have additional benefits as well. For example, diseased motor neurons grown in cell culture dishes can be quickly and efficiently screened with potential drugs to discover agents that slow, halt or reverse the cellular damage. It is our hope that these experiments will both deepen our understanding of important neurodegenerative disorders, and lead to new directions for the development of effective therapies.
We have made the resource of Floxin vectors and the greater than 24,000 characterized Floxin compatible ESC lines available to the research community. Application of the Floxin technology to this resource will allow genetic modification of more than 4,500 genes in ESCs. Furthermore, we are adapting the Floxin technology for use in human ESCs which may allow for tractable genetic engineering in these cells. We anticipate that this technology will allow many researchers to create cellular models of human disease and other genetic modifications that will facilitate the use of stem cells in fighting diverse diseases.