This would increase the chance of getting a good transplant.

Right now, the techniques for gene therapy are kind of brute force. You put the gene in and hope it goes into the right place. There's no selection. What we would like to do is put the gene into stem cells, grow them and watch them to be as sure as one can be that we've got the right gene into the right cells and nothing untoward has happened.

We want to understand how stem cells make this decision to differentiate or stay stem cells. What signals do they get? These are big questions, difficult questions, and we need to answer them. These are hard questions, but slowly we'll get the ability to answer them.