“The adenovirus will infect the cells but then will clear themselves from the cells. After a few cell divisions there are no traces of the virus in the cell,” Hochedlinger said. “You can’t tell the virus was ever there.”
Science Magazine has published a report on induced Pluripotent (iPS) stem cells from liver cells (hepatacytes) that do not show any trace of the viruses initially used to cause the regression from adult cells to embryonic-like stem cells. The report, by Hochedlinger‘s group at Massachusetts Gener al Hospital and Harvard, is behind a pay-wall, but there is a review here at the Washington Post.
The simple explanation is that viruses are used to carry copies of genes that turn on proteins which cause the cells to divide and produce embryonic-like stem cells. Prior research used viruses that might become permanently inserted into the DNA of the cells. These viruses did not cause an infection in the culture because the viruses used were not good at causing themselves to be reproduced or inserting themselves into neighboring cells. However, because they inserted themselves into the DNA, there was a risk that the cells could become mutated or even cause tumors due to the abnormal DNA that resulted. In the case of Hochedlinger’s cells, the adenovirus used does not insert into the DNA nearly as often, and when it does, the cell is able to repair the DNA in subsequent copies of the DNA as it reproduces the nucleus of the cell in order to divide to become two cells.
The cells are infected, they change because of the infection, but their granddaughters are able to get rid of the infection, while continuing to act like embryonic stem cells instead of grown up liver cells. The new “adeno-iPS” cells pass all the tests for “stemness.”
Just think, no need for egg cells, no cloning, no destruction of embryos, and we’re one step closer to healing within the body – to learning how to heal without transplant rejection or tumors due to the treatment. One day, we may be able to regenerate organs and tissues in place, as needed.