Year 1

The goal of the project is to find a new way to make adult cells such as skin cells into stem cells that have the capacity to differentiate into many tissues. The original method to do this “reprogramming” used viruses, which can make the cells cancer-prone. We are developing a new method that does not use viruses and is expected to be safer. To initiate the studies, we constructed several new plasmids, or circles of DNA, that carry two to four genes that can stimulate adult cells to turn into stem cells. We also included a section of DNA that carries an “insert me” signal that causes the plasmid to become integrated into the cell’s chromosomes when an integrase enzyme is present. These plasmids have the potential to reprogram cells, and we are testing them to see which ones work the best. The next objective was to find methods to introduce the plasmid DNA efficiently into the mouse and human cells that we wanted to reprogram. We tried a series of chemical agents and also tried a method that uses an electric shock to disrupt the cell membrane. The latter method, called electroporation, worked the best. Using these methods, we verified that the reprogramming genes that we placed on the plasmid worked. We used electroporation to introduce a reprogramming plasmid and a plasmid carrying the gene for integrase into skin cells and observed colonies of cells that had the characteristics of embryonic stem cells. Because of the great potential of being able to make cells similar to embryonic stem cells out of ordinary adult cells, many scientific groups are working in this field and have made novel contributions. For example, it has been discovered that certain types of adult cells are easier to reprogram than others and that it is possible to substitute small molecules for some of the reprogramming genes. We plan to combine some of these advances with our approach, in order to increase the efficiency of reprogramming, use fewer reprogramming genes, and produce higher quality reprogrammed cells. In the next year, we will carry out that work, as well as thoroughly characterizing the reprogrammed cells that we produce, in terms of their ability to differentiate into different tissue types and show other features of embryonic stem cells. We will also begin experiments to use reprogrammed cells made with these methods to cure genetic diseases.