Toronto scientists at Mount Sinai Hospital have discovered problems in using reprogrammed stem cells for personalized organ repair. “It looks like the reprogramming process which creates (embryonic-like) stem cells from skin cells is creating damage or mutations,” said Andras Nagy, one of the lead authors of the study published in the journal Nature. These cells, known as induced pluripotent stem cells (iPS cells), were found by researchers to have three times as many genetic mutations as embryonic stem cells. In 2007, scientists discovered how to create iPS cells using potentially cancer-causing viruses. They do not yet know whether the mutations are good or bad and will have to turn the cells into a particular tissue type to assess the effect of the mutations. The iPS cells were lauded as ethical alternatives to embryonic stem cell research that requires the destruction of human beings at the embryo stage of development.