An advance in stem cell research has been presented in Nature online this week, that is expected to permanently change the field of regenerative medicine from this time forward. Scientists from Mt. Sinai Hospital in Toronto Canada, in collaboration with the University of Edinburgh, UK, report finding a new way to reprogram human adult cells to revert to a pluripotent state, resembling stem cells, without the risks of cancer that have previously been observed.
Until now, research on human (skin) cell lines has involved reprogramming using transfection with viral vectors. One of the main complications of this method is that the viral DNA inserts into human DNA randomly and can interrupt other genes, causing mutations that may lead to cancer. The new technique results in iPS cells (induced pluripotent stem cells) without the use of viruses. Insertion of genes for the factors that cause pluripotency, is done using a transposon (a piece of circular, non-viral DNA, that inserts itself into a genome), followed by their later removal using a transposase enzyme.
The new method minimizes genetic alterations in the resulting cell line, and removes factors that are important for pluripotency but can cause problems later during cell development and differentiation. If it can be demonstrated that this method is predictable and reliable enough, it could be a lifesaver for millions needing organ transplants, as compatible organs might be grown from each individual recipientís own skin or other cells.
Hayden, E. and Baker, M. Virus-free pluripotency for human cells. Nature News (online), February 27, 2009. doi:10.1038/458019a.
Woltjen, K. et al. piggyback transposition reprograms fibroblasts to induced pluripotent stem cells. Nature advance online publication March 1, 2009. doi:10.1038/nature07863.
Kaji, K. et al. Virus-free induction of pluripotency and subsequent excision of reprogramming factors. Nature advance online publication March 1, 2009. doi:10.1038/nature07864.