EurekAlert reports that scientists have successfully used gene therapy to get mice immune systems to accept grafts of dead bone (a common procedure for drastic bone loss in humans). "Everyday activities cause microscopic fractures in our bones ... when the bone is dead, there is no healing, and those tiny fractures begin to accumulate until finally, perhaps in 10 years, the implanted section collapses, and more drastic surgery becomes necessary. ... the virus permeated the inflammatory tissue around the dead bone and turned on the genes. The mouse body then began to treat the implanted bone as if it were its own tissue instead of a foreign object ... It's at that point that the body actually begins changing the dead, foreign bone splint, into the body's own, whole, living bone."

Link: http://www.eurekalert.org/pub_releases/2005-02/uorm-gtc021805.php