On transplanting cells, not organs

This is fascinating. Here Susan Lim discussed the benefits of using iPS cells, and other stem cells in new forms of transplants.
These are adult cells taken from a patient's body and then turned back into undifferentiated, or pluripotent cells. Pluripotent cells can become any cell type in the body, which is really useful considering that adult stem cells eg. from the bone marrow, can't. Using embryonic stem cells, which is the alternative, is also fraught with ethical and moral dilemmas that go back to the question of whether an embryo is human; ie. when life begins. So this seems like a great way to go: however, consider this article in the Guardian that discusses a recent study where iPS cells were rejected in mice.
This is shocking because the iPS cells in the study came from the mouse itself, so in a way the mice were rejecting their own cells. The cells that came from iPS cells were implanted and then quickly destroyed by the mouse's immune system, whereas stem cells from embryos were not. The study is published in Nature.
This is probably down to abnormal gene expression, which has also been noticed in a variety of other cases. Cells derived from iPS cells have also been known to create tumours and a variety of problems, so they may not actually be the best way forwards.
Consider this article in the Guardian discussing the potential of reprogramming rather than transplanting tissue. Since these cells turn from one type to another, skipping the stem cell phase (ie. they re-differentiate), perhaps the ugly problems in iPS cell studies could be avoided.
This topic is very interesting, and research on stem cells and other forms of transplants and tissue repair are always emerging. The debate over transplanting organs and limbs vs. transplanting cells is also something to consider.