Canadian Press TORONTO — Scientists at Toronto's Hospital for Sick Children say they've taken a step forward in stem-cell transplant research. They've discovered a gene with properties that allow for successful transfer of stem cells from human bone marrow into mice. They also identified the type of cell that expresses the gene (called SIRPalpha) and is responsible for either destroying or supporting growth of human blood stem cells. The researchers hope further studies will lead to the development of a therapy so more children with blood diseases can receive bone marrow transplantation. It may also help provide a genetic test...